MIPS: Tracing: Add dynamic function tracer support
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.
But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:
MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.
For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:
108: 03e0082d move at,ra
10c: 0c000000 jal 0 <fpcsr_pending>
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nop
For the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".
and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.
but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.
the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:
lui v1,0x0
addiu v1,v1,0
If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_caller
If we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.
Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:
_mcount:
ftrace_caller:
j ftrace_stub
nop
...(do real tracing here)...
ftrace_stub:
jr ra
move ra, at
By default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.
what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)
In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:32 +08:00
|
|
|
/*
|
|
|
|
|
* Code for replacing ftrace calls with jumps.
|
|
|
|
|
*
|
|
|
|
|
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
|
2010-05-14 19:08:32 +08:00
|
|
|
* Copyright (C) 2009, 2010 DSLab, Lanzhou University, China
|
2010-01-04 17:16:51 +08:00
|
|
|
* Author: Wu Zhangjin <wuzhangjin@gmail.com>
|
MIPS: Tracing: Add dynamic function tracer support
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.
But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:
MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.
For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:
108: 03e0082d move at,ra
10c: 0c000000 jal 0 <fpcsr_pending>
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nop
For the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".
and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.
but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.
the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:
lui v1,0x0
addiu v1,v1,0
If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_caller
If we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.
Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:
_mcount:
ftrace_caller:
j ftrace_stub
nop
...(do real tracing here)...
ftrace_stub:
jr ra
move ra, at
By default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.
what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)
In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:32 +08:00
|
|
|
*
|
|
|
|
|
* Thanks goes to Steven Rostedt for writing the original x86 version.
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
#include <linux/uaccess.h>
|
|
|
|
|
#include <linux/init.h>
|
|
|
|
|
#include <linux/ftrace.h>
|
|
|
|
|
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
#include <asm/asm.h>
|
|
|
|
|
#include <asm/asm-offsets.h>
|
2010-05-14 19:08:32 +08:00
|
|
|
#include <asm/cacheflush.h>
|
|
|
|
|
#include <asm/uasm.h>
|
MIPS: Tracing: Add dynamic function tracer support
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.
But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:
MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.
For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:
108: 03e0082d move at,ra
10c: 0c000000 jal 0 <fpcsr_pending>
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nop
For the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".
and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.
but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.
the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:
lui v1,0x0
addiu v1,v1,0
If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_caller
If we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.
Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:
_mcount:
ftrace_caller:
j ftrace_stub
nop
...(do real tracing here)...
ftrace_stub:
jr ra
move ra, at
By default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.
what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)
In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:32 +08:00
|
|
|
|
2011-01-20 03:28:29 +08:00
|
|
|
#include <asm-generic/sections.h>
|
2010-05-14 19:08:34 +08:00
|
|
|
|
MIPS: Tracing: Add dynamic function tracer support
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.
But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:
MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.
For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:
108: 03e0082d move at,ra
10c: 0c000000 jal 0 <fpcsr_pending>
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nop
For the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".
and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.
but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.
the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:
lui v1,0x0
addiu v1,v1,0
If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_caller
If we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.
Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:
_mcount:
ftrace_caller:
j ftrace_stub
nop
...(do real tracing here)...
ftrace_stub:
jr ra
move ra, at
By default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.
what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)
In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:32 +08:00
|
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
|
|
|
|
|
|
|
|
|
#define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */
|
|
|
|
|
#define ADDR_MASK 0x03ffffff /* op_code|addr : 31...26|25 ....0 */
|
|
|
|
|
|
2010-05-14 19:08:31 +08:00
|
|
|
#define INSN_NOP 0x00000000 /* nop */
|
2010-05-14 19:08:32 +08:00
|
|
|
#define INSN_JAL(addr) \
|
|
|
|
|
((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK)))
|
|
|
|
|
|
|
|
|
|
static unsigned int insn_jal_ftrace_caller __read_mostly;
|
|
|
|
|
static unsigned int insn_lui_v1_hi16_mcount __read_mostly;
|
|
|
|
|
static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly;
|
|
|
|
|
|
|
|
|
|
static inline void ftrace_dyn_arch_init_insns(void)
|
|
|
|
|
{
|
|
|
|
|
u32 *buf;
|
|
|
|
|
unsigned int v1;
|
|
|
|
|
|
|
|
|
|
/* lui v1, hi16_mcount */
|
|
|
|
|
v1 = 3;
|
|
|
|
|
buf = (u32 *)&insn_lui_v1_hi16_mcount;
|
|
|
|
|
UASM_i_LA_mostly(&buf, v1, MCOUNT_ADDR);
|
|
|
|
|
|
|
|
|
|
/* jal (ftrace_caller + 8), jump over the first two instruction */
|
|
|
|
|
buf = (u32 *)&insn_jal_ftrace_caller;
|
|
|
|
|
uasm_i_jal(&buf, (FTRACE_ADDR + 8));
|
|
|
|
|
|
|
|
|
|
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
|
|
|
|
|
/* j ftrace_graph_caller */
|
|
|
|
|
buf = (u32 *)&insn_j_ftrace_graph_caller;
|
|
|
|
|
uasm_i_j(&buf, (unsigned long)ftrace_graph_caller);
|
|
|
|
|
#endif
|
|
|
|
|
}
|
MIPS: Tracing: Add dynamic function tracer support
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.
But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:
MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.
For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:
108: 03e0082d move at,ra
10c: 0c000000 jal 0 <fpcsr_pending>
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nop
For the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".
and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.
but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.
the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:
lui v1,0x0
addiu v1,v1,0
If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_caller
If we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.
Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:
_mcount:
ftrace_caller:
j ftrace_stub
nop
...(do real tracing here)...
ftrace_stub:
jr ra
move ra, at
By default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.
what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)
In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:32 +08:00
|
|
|
|
2011-01-20 03:28:29 +08:00
|
|
|
/*
|
|
|
|
|
* Check if the address is in kernel space
|
|
|
|
|
*
|
|
|
|
|
* Clone core_kernel_text() from kernel/extable.c, but doesn't call
|
|
|
|
|
* init_kernel_text() for Ftrace doesn't trace functions in init sections.
|
|
|
|
|
*/
|
|
|
|
|
static inline int in_kernel_space(unsigned long ip)
|
|
|
|
|
{
|
|
|
|
|
if (ip >= (unsigned long)_stext &&
|
|
|
|
|
ip <= (unsigned long)_etext)
|
|
|
|
|
return 1;
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
MIPS: Tracing: Add dynamic function tracer support
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.
But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:
MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.
For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:
108: 03e0082d move at,ra
10c: 0c000000 jal 0 <fpcsr_pending>
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nop
For the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".
and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.
but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.
the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:
lui v1,0x0
addiu v1,v1,0
If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_caller
If we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.
Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:
_mcount:
ftrace_caller:
j ftrace_stub
nop
...(do real tracing here)...
ftrace_stub:
jr ra
move ra, at
By default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.
what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)
In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:32 +08:00
|
|
|
static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
|
|
|
|
|
{
|
2009-11-20 20:34:36 +08:00
|
|
|
int faulted;
|
|
|
|
|
|
|
|
|
|
/* *(unsigned int *)ip = new_code; */
|
|
|
|
|
safe_store_code(new_code, ip, faulted);
|
|
|
|
|
|
|
|
|
|
if (unlikely(faulted))
|
|
|
|
|
return -EFAULT;
|
MIPS: Tracing: Add dynamic function tracer support
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.
But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:
MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.
For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:
108: 03e0082d move at,ra
10c: 0c000000 jal 0 <fpcsr_pending>
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nop
For the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".
and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.
but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.
the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:
lui v1,0x0
addiu v1,v1,0
If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_caller
If we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.
Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:
_mcount:
ftrace_caller:
j ftrace_stub
nop
...(do real tracing here)...
ftrace_stub:
jr ra
move ra, at
By default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.
what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)
In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:32 +08:00
|
|
|
|
|
|
|
|
flush_icache_range(ip, ip + 8);
|
|
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
2011-01-20 03:28:31 +08:00
|
|
|
/*
|
|
|
|
|
* The details about the calling site of mcount on MIPS
|
|
|
|
|
*
|
|
|
|
|
* 1. For kernel:
|
|
|
|
|
*
|
|
|
|
|
* move at, ra
|
|
|
|
|
* jal _mcount --> nop
|
|
|
|
|
*
|
|
|
|
|
* 2. For modules:
|
|
|
|
|
*
|
|
|
|
|
* 2.1 For KBUILD_MCOUNT_RA_ADDRESS and CONFIG_32BIT
|
|
|
|
|
*
|
|
|
|
|
* lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
|
|
|
|
|
* addiu v1, v1, low_16bit_of_mcount
|
|
|
|
|
* move at, ra
|
|
|
|
|
* move $12, ra_address
|
|
|
|
|
* jalr v1
|
|
|
|
|
* sub sp, sp, 8
|
|
|
|
|
* 1: offset = 5 instructions
|
|
|
|
|
* 2.2 For the Other situations
|
|
|
|
|
*
|
|
|
|
|
* lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
|
|
|
|
|
* addiu v1, v1, low_16bit_of_mcount
|
|
|
|
|
* move at, ra
|
|
|
|
|
* jalr v1
|
|
|
|
|
* nop | move $12, ra_address | sub sp, sp, 8
|
|
|
|
|
* 1: offset = 4 instructions
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
|
|
|
|
|
#define MCOUNT_OFFSET_INSNS 5
|
|
|
|
|
#else
|
|
|
|
|
#define MCOUNT_OFFSET_INSNS 4
|
|
|
|
|
#endif
|
|
|
|
|
#define INSN_B_1F (0x10000000 | MCOUNT_OFFSET_INSNS)
|
|
|
|
|
|
MIPS: Tracing: Add dynamic function tracer support
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.
But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:
MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.
For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:
108: 03e0082d move at,ra
10c: 0c000000 jal 0 <fpcsr_pending>
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nop
For the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".
and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.
but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.
the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:
lui v1,0x0
addiu v1,v1,0
If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_caller
If we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.
Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:
_mcount:
ftrace_caller:
j ftrace_stub
nop
...(do real tracing here)...
ftrace_stub:
jr ra
move ra, at
By default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.
what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)
In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:32 +08:00
|
|
|
int ftrace_make_nop(struct module *mod,
|
|
|
|
|
struct dyn_ftrace *rec, unsigned long addr)
|
|
|
|
|
{
|
|
|
|
|
unsigned int new;
|
|
|
|
|
unsigned long ip = rec->ip;
|
|
|
|
|
|
2010-05-14 19:08:32 +08:00
|
|
|
/*
|
2011-01-20 03:28:29 +08:00
|
|
|
* If ip is in kernel space, no long call, otherwise, long call is
|
|
|
|
|
* needed.
|
2010-05-14 19:08:32 +08:00
|
|
|
*/
|
2011-01-20 03:28:31 +08:00
|
|
|
new = in_kernel_space(ip) ? INSN_NOP : INSN_B_1F;
|
|
|
|
|
|
MIPS: Tracing: Add dynamic function tracer support
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.
But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:
MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.
For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:
108: 03e0082d move at,ra
10c: 0c000000 jal 0 <fpcsr_pending>
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nop
For the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".
and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.
but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.
the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:
lui v1,0x0
addiu v1,v1,0
If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_caller
If we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.
Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:
_mcount:
ftrace_caller:
j ftrace_stub
nop
...(do real tracing here)...
ftrace_stub:
jr ra
move ra, at
By default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.
what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)
In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:32 +08:00
|
|
|
return ftrace_modify_code(ip, new);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
|
|
|
|
|
{
|
|
|
|
|
unsigned int new;
|
|
|
|
|
unsigned long ip = rec->ip;
|
|
|
|
|
|
2011-01-20 03:28:29 +08:00
|
|
|
new = in_kernel_space(ip) ? insn_jal_ftrace_caller :
|
|
|
|
|
insn_lui_v1_hi16_mcount;
|
MIPS: Tracing: Add dynamic function tracer support
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.
But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:
MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.
For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:
108: 03e0082d move at,ra
10c: 0c000000 jal 0 <fpcsr_pending>
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nop
For the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".
and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.
but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.
the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:
lui v1,0x0
addiu v1,v1,0
If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_caller
If we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.
Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:
_mcount:
ftrace_caller:
j ftrace_stub
nop
...(do real tracing here)...
ftrace_stub:
jr ra
move ra, at
By default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.
what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)
In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:32 +08:00
|
|
|
|
|
|
|
|
return ftrace_modify_code(ip, new);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
#define FTRACE_CALL_IP ((unsigned long)(&ftrace_call))
|
|
|
|
|
|
|
|
|
|
int ftrace_update_ftrace_func(ftrace_func_t func)
|
|
|
|
|
{
|
|
|
|
|
unsigned int new;
|
|
|
|
|
|
2010-05-14 19:08:31 +08:00
|
|
|
new = INSN_JAL((unsigned long)func);
|
MIPS: Tracing: Add dynamic function tracer support
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.
But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:
MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.
For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:
108: 03e0082d move at,ra
10c: 0c000000 jal 0 <fpcsr_pending>
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nop
For the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".
and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.
but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.
the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:
lui v1,0x0
addiu v1,v1,0
If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_caller
If we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.
Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:
_mcount:
ftrace_caller:
j ftrace_stub
nop
...(do real tracing here)...
ftrace_stub:
jr ra
move ra, at
By default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.
what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)
In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:32 +08:00
|
|
|
|
|
|
|
|
return ftrace_modify_code(FTRACE_CALL_IP, new);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
int __init ftrace_dyn_arch_init(void *data)
|
|
|
|
|
{
|
2010-05-14 19:08:32 +08:00
|
|
|
/* Encode the instructions when booting */
|
|
|
|
|
ftrace_dyn_arch_init_insns();
|
|
|
|
|
|
|
|
|
|
/* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */
|
|
|
|
|
ftrace_modify_code(MCOUNT_ADDR, INSN_NOP);
|
|
|
|
|
|
MIPS: Tracing: Add dynamic function tracer support
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.
But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:
MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.
For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:
108: 03e0082d move at,ra
10c: 0c000000 jal 0 <fpcsr_pending>
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nop
For the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".
and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.
but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.
the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:
lui v1,0x0
addiu v1,v1,0
If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_caller
If we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.
Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:
_mcount:
ftrace_caller:
j ftrace_stub
nop
...(do real tracing here)...
ftrace_stub:
jr ra
move ra, at
By default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.
what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)
In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:32 +08:00
|
|
|
/* The return code is retured via data */
|
|
|
|
|
*(unsigned long *)data = 0;
|
|
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
2010-05-14 19:08:33 +08:00
|
|
|
#endif /* CONFIG_DYNAMIC_FTRACE */
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
|
|
|
|
|
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
|
|
|
|
|
|
2009-11-20 20:34:35 +08:00
|
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
|
|
|
|
|
|
|
|
|
extern void ftrace_graph_call(void);
|
|
|
|
|
#define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call))
|
|
|
|
|
|
|
|
|
|
int ftrace_enable_ftrace_graph_caller(void)
|
|
|
|
|
{
|
|
|
|
|
return ftrace_modify_code(FTRACE_GRAPH_CALL_IP,
|
2010-05-14 19:08:32 +08:00
|
|
|
insn_j_ftrace_graph_caller);
|
2009-11-20 20:34:35 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
int ftrace_disable_ftrace_graph_caller(void)
|
|
|
|
|
{
|
2010-05-14 19:08:31 +08:00
|
|
|
return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP);
|
2009-11-20 20:34:35 +08:00
|
|
|
}
|
|
|
|
|
|
2010-05-14 19:08:33 +08:00
|
|
|
#endif /* CONFIG_DYNAMIC_FTRACE */
|
2009-11-20 20:34:35 +08:00
|
|
|
|
MIPS: Tracing: Make function graph tracer work with -mmcount-ra-address
That thread "MIPS: Add option to pass return address location to
_mcount" from "David Daney <ddaney@caviumnetworks.com>" have added a new
option -mmcount-ra-address to gcc(4.5) for MIPS to transfer the location
of the return address to _mcount.
Benefit from this new feature, function graph tracer on MIPS will be
easier and safer to hijack the return address of the kernel function,
which will save some overhead and make the whole thing more reliable.
In this patch, at first, try to enable the option -mmcount-ra-address in
arch/mips/Makefile with cc-option, if gcc support it, it will be
enabled, otherwise, no side effect.
and then, we need to support this new option of gcc 4.5 and also support
the old gcc versions.
with _mcount in the old gcc versions, it's not easy to get the location
of return address(tracing: add function graph tracer support for MIPS),
so, we do it in a C function: ftrace_get_parent_addr(ftrace.c), but
with -mmcount-ra-address, only several instructions need to get what
we want, so, I put into asm(mcount.S). and also, as the $12(t0) is
used by -mmcount-ra-address for transferring the localtion of return
address to _mcount, we need to save it into the stack and restore it
when enabled dynamic function tracer, 'Cause we have called
"ftrace_call" before "ftrace_graph_caller", which may destroy
$12(t0).
(Thanks to David for providing that -mcount-ra-address and giving the
idea of KBUILD_MCOUNT_RA_ADDRESS, both of them have made the whole
thing more beautiful!)
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/681/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:38 +08:00
|
|
|
#ifndef KBUILD_MCOUNT_RA_ADDRESS
|
2010-05-14 19:08:33 +08:00
|
|
|
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
#define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */
|
|
|
|
|
#define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */
|
|
|
|
|
#define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */
|
|
|
|
|
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long
|
|
|
|
|
old_parent_ra, unsigned long parent_ra_addr, unsigned long fp)
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
{
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
unsigned long sp, ip, tmp;
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
unsigned int code;
|
2009-11-20 20:34:36 +08:00
|
|
|
int faulted;
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
|
2010-05-14 19:08:33 +08:00
|
|
|
/*
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
* For module, move the ip from the return address after the
|
2011-01-20 03:28:27 +08:00
|
|
|
* instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for
|
|
|
|
|
* kernel, move after the instruction "move ra, at"(offset is 16)
|
2010-05-14 19:08:33 +08:00
|
|
|
*/
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
ip = self_ra - (in_kernel_space(self_ra) ? 16 : 24);
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
|
2010-05-14 19:08:33 +08:00
|
|
|
/*
|
|
|
|
|
* search the text until finding the non-store instruction or "s{d,w}
|
|
|
|
|
* ra, offset(sp)" instruction
|
|
|
|
|
*/
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
do {
|
2009-11-20 20:34:36 +08:00
|
|
|
/* get the code at "ip": code = *(unsigned int *)ip; */
|
|
|
|
|
safe_load_code(code, ip, faulted);
|
|
|
|
|
|
|
|
|
|
if (unlikely(faulted))
|
|
|
|
|
return 0;
|
2010-05-14 19:08:33 +08:00
|
|
|
/*
|
|
|
|
|
* If we hit the non-store instruction before finding where the
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
* ra is stored, then this is a leaf function and it does not
|
2010-05-14 19:08:33 +08:00
|
|
|
* store the ra on the stack
|
|
|
|
|
*/
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
if ((code & S_R_SP) != S_R_SP)
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
return parent_ra_addr;
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
|
2011-01-20 03:28:27 +08:00
|
|
|
/* Move to the next instruction */
|
|
|
|
|
ip -= 4;
|
|
|
|
|
} while ((code & S_RA_SP) != S_RA_SP);
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
|
|
|
|
|
sp = fp + (code & OFFSET_MASK);
|
2009-11-20 20:34:36 +08:00
|
|
|
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
/* tmp = *(unsigned long *)sp; */
|
|
|
|
|
safe_load_stack(tmp, sp, faulted);
|
2009-11-20 20:34:36 +08:00
|
|
|
if (unlikely(faulted))
|
|
|
|
|
return 0;
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
if (tmp == old_parent_ra)
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
return sp;
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
2010-05-14 19:08:33 +08:00
|
|
|
#endif /* !KBUILD_MCOUNT_RA_ADDRESS */
|
MIPS: Tracing: Make function graph tracer work with -mmcount-ra-address
That thread "MIPS: Add option to pass return address location to
_mcount" from "David Daney <ddaney@caviumnetworks.com>" have added a new
option -mmcount-ra-address to gcc(4.5) for MIPS to transfer the location
of the return address to _mcount.
Benefit from this new feature, function graph tracer on MIPS will be
easier and safer to hijack the return address of the kernel function,
which will save some overhead and make the whole thing more reliable.
In this patch, at first, try to enable the option -mmcount-ra-address in
arch/mips/Makefile with cc-option, if gcc support it, it will be
enabled, otherwise, no side effect.
and then, we need to support this new option of gcc 4.5 and also support
the old gcc versions.
with _mcount in the old gcc versions, it's not easy to get the location
of return address(tracing: add function graph tracer support for MIPS),
so, we do it in a C function: ftrace_get_parent_addr(ftrace.c), but
with -mmcount-ra-address, only several instructions need to get what
we want, so, I put into asm(mcount.S). and also, as the $12(t0) is
used by -mmcount-ra-address for transferring the localtion of return
address to _mcount, we need to save it into the stack and restore it
when enabled dynamic function tracer, 'Cause we have called
"ftrace_call" before "ftrace_graph_caller", which may destroy
$12(t0).
(Thanks to David for providing that -mcount-ra-address and giving the
idea of KBUILD_MCOUNT_RA_ADDRESS, both of them have made the whole
thing more beautiful!)
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/681/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:38 +08:00
|
|
|
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
/*
|
|
|
|
|
* Hook the return address and push it in the stack of return addrs
|
|
|
|
|
* in current thread info.
|
|
|
|
|
*/
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
unsigned long fp)
|
|
|
|
|
{
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
unsigned long old_parent_ra;
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
struct ftrace_graph_ent trace;
|
|
|
|
|
unsigned long return_hooker = (unsigned long)
|
|
|
|
|
&return_to_handler;
|
2011-01-22 02:01:53 +08:00
|
|
|
int faulted, insns;
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
|
|
|
|
|
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
|
|
|
|
|
return;
|
|
|
|
|
|
2010-05-14 19:08:33 +08:00
|
|
|
/*
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
* "parent_ra_addr" is the stack address saved the return address of
|
|
|
|
|
* the caller of _mcount.
|
MIPS: Tracing: Make function graph tracer work with -mmcount-ra-address
That thread "MIPS: Add option to pass return address location to
_mcount" from "David Daney <ddaney@caviumnetworks.com>" have added a new
option -mmcount-ra-address to gcc(4.5) for MIPS to transfer the location
of the return address to _mcount.
Benefit from this new feature, function graph tracer on MIPS will be
easier and safer to hijack the return address of the kernel function,
which will save some overhead and make the whole thing more reliable.
In this patch, at first, try to enable the option -mmcount-ra-address in
arch/mips/Makefile with cc-option, if gcc support it, it will be
enabled, otherwise, no side effect.
and then, we need to support this new option of gcc 4.5 and also support
the old gcc versions.
with _mcount in the old gcc versions, it's not easy to get the location
of return address(tracing: add function graph tracer support for MIPS),
so, we do it in a C function: ftrace_get_parent_addr(ftrace.c), but
with -mmcount-ra-address, only several instructions need to get what
we want, so, I put into asm(mcount.S). and also, as the $12(t0) is
used by -mmcount-ra-address for transferring the localtion of return
address to _mcount, we need to save it into the stack and restore it
when enabled dynamic function tracer, 'Cause we have called
"ftrace_call" before "ftrace_graph_caller", which may destroy
$12(t0).
(Thanks to David for providing that -mcount-ra-address and giving the
idea of KBUILD_MCOUNT_RA_ADDRESS, both of them have made the whole
thing more beautiful!)
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/681/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:38 +08:00
|
|
|
*
|
|
|
|
|
* if the gcc < 4.5, a leaf function does not save the return address
|
|
|
|
|
* in the stack address, so, we "emulate" one in _mcount's stack space,
|
|
|
|
|
* and hijack it directly, but for a non-leaf function, it save the
|
|
|
|
|
* return address to the its own stack space, we can not hijack it
|
|
|
|
|
* directly, but need to find the real stack address,
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
* ftrace_get_parent_addr() does it!
|
MIPS: Tracing: Make function graph tracer work with -mmcount-ra-address
That thread "MIPS: Add option to pass return address location to
_mcount" from "David Daney <ddaney@caviumnetworks.com>" have added a new
option -mmcount-ra-address to gcc(4.5) for MIPS to transfer the location
of the return address to _mcount.
Benefit from this new feature, function graph tracer on MIPS will be
easier and safer to hijack the return address of the kernel function,
which will save some overhead and make the whole thing more reliable.
In this patch, at first, try to enable the option -mmcount-ra-address in
arch/mips/Makefile with cc-option, if gcc support it, it will be
enabled, otherwise, no side effect.
and then, we need to support this new option of gcc 4.5 and also support
the old gcc versions.
with _mcount in the old gcc versions, it's not easy to get the location
of return address(tracing: add function graph tracer support for MIPS),
so, we do it in a C function: ftrace_get_parent_addr(ftrace.c), but
with -mmcount-ra-address, only several instructions need to get what
we want, so, I put into asm(mcount.S). and also, as the $12(t0) is
used by -mmcount-ra-address for transferring the localtion of return
address to _mcount, we need to save it into the stack and restore it
when enabled dynamic function tracer, 'Cause we have called
"ftrace_call" before "ftrace_graph_caller", which may destroy
$12(t0).
(Thanks to David for providing that -mcount-ra-address and giving the
idea of KBUILD_MCOUNT_RA_ADDRESS, both of them have made the whole
thing more beautiful!)
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/681/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:38 +08:00
|
|
|
*
|
|
|
|
|
* if gcc>= 4.5, with the new -mmcount-ra-address option, for a
|
|
|
|
|
* non-leaf function, the location of the return address will be saved
|
|
|
|
|
* to $12 for us, and for a leaf function, only put a zero into $12. we
|
|
|
|
|
* do it in ftrace_graph_caller of mcount.S.
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
*/
|
|
|
|
|
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
/* old_parent_ra = *parent_ra_addr; */
|
|
|
|
|
safe_load_stack(old_parent_ra, parent_ra_addr, faulted);
|
2009-11-20 20:34:36 +08:00
|
|
|
if (unlikely(faulted))
|
|
|
|
|
goto out;
|
MIPS: Tracing: Make function graph tracer work with -mmcount-ra-address
That thread "MIPS: Add option to pass return address location to
_mcount" from "David Daney <ddaney@caviumnetworks.com>" have added a new
option -mmcount-ra-address to gcc(4.5) for MIPS to transfer the location
of the return address to _mcount.
Benefit from this new feature, function graph tracer on MIPS will be
easier and safer to hijack the return address of the kernel function,
which will save some overhead and make the whole thing more reliable.
In this patch, at first, try to enable the option -mmcount-ra-address in
arch/mips/Makefile with cc-option, if gcc support it, it will be
enabled, otherwise, no side effect.
and then, we need to support this new option of gcc 4.5 and also support
the old gcc versions.
with _mcount in the old gcc versions, it's not easy to get the location
of return address(tracing: add function graph tracer support for MIPS),
so, we do it in a C function: ftrace_get_parent_addr(ftrace.c), but
with -mmcount-ra-address, only several instructions need to get what
we want, so, I put into asm(mcount.S). and also, as the $12(t0) is
used by -mmcount-ra-address for transferring the localtion of return
address to _mcount, we need to save it into the stack and restore it
when enabled dynamic function tracer, 'Cause we have called
"ftrace_call" before "ftrace_graph_caller", which may destroy
$12(t0).
(Thanks to David for providing that -mcount-ra-address and giving the
idea of KBUILD_MCOUNT_RA_ADDRESS, both of them have made the whole
thing more beautiful!)
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/681/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:38 +08:00
|
|
|
#ifndef KBUILD_MCOUNT_RA_ADDRESS
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
parent_ra_addr = (unsigned long *)ftrace_get_parent_ra_addr(self_ra,
|
|
|
|
|
old_parent_ra, (unsigned long)parent_ra_addr, fp);
|
2010-05-14 19:08:33 +08:00
|
|
|
/*
|
|
|
|
|
* If fails when getting the stack address of the non-leaf function's
|
|
|
|
|
* ra, stop function graph tracer and return
|
|
|
|
|
*/
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
if (parent_ra_addr == 0)
|
2009-11-20 20:34:36 +08:00
|
|
|
goto out;
|
MIPS: Tracing: Make function graph tracer work with -mmcount-ra-address
That thread "MIPS: Add option to pass return address location to
_mcount" from "David Daney <ddaney@caviumnetworks.com>" have added a new
option -mmcount-ra-address to gcc(4.5) for MIPS to transfer the location
of the return address to _mcount.
Benefit from this new feature, function graph tracer on MIPS will be
easier and safer to hijack the return address of the kernel function,
which will save some overhead and make the whole thing more reliable.
In this patch, at first, try to enable the option -mmcount-ra-address in
arch/mips/Makefile with cc-option, if gcc support it, it will be
enabled, otherwise, no side effect.
and then, we need to support this new option of gcc 4.5 and also support
the old gcc versions.
with _mcount in the old gcc versions, it's not easy to get the location
of return address(tracing: add function graph tracer support for MIPS),
so, we do it in a C function: ftrace_get_parent_addr(ftrace.c), but
with -mmcount-ra-address, only several instructions need to get what
we want, so, I put into asm(mcount.S). and also, as the $12(t0) is
used by -mmcount-ra-address for transferring the localtion of return
address to _mcount, we need to save it into the stack and restore it
when enabled dynamic function tracer, 'Cause we have called
"ftrace_call" before "ftrace_graph_caller", which may destroy
$12(t0).
(Thanks to David for providing that -mcount-ra-address and giving the
idea of KBUILD_MCOUNT_RA_ADDRESS, both of them have made the whole
thing more beautiful!)
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/681/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:38 +08:00
|
|
|
#endif
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
/* *parent_ra_addr = return_hooker; */
|
|
|
|
|
safe_store_stack(return_hooker, parent_ra_addr, faulted);
|
2009-11-20 20:34:36 +08:00
|
|
|
if (unlikely(faulted))
|
|
|
|
|
goto out;
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp)
|
|
|
|
|
== -EBUSY) {
|
|
|
|
|
*parent_ra_addr = old_parent_ra;
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
return;
|
|
|
|
|
}
|
|
|
|
|
|
2011-01-22 02:01:53 +08:00
|
|
|
/*
|
|
|
|
|
* Get the recorded ip of the current mcount calling site in the
|
|
|
|
|
* __mcount_loc section, which will be used to filter the function
|
|
|
|
|
* entries configured through the tracing/set_graph_function interface.
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
insns = in_kernel_space(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1;
|
|
|
|
|
trace.func = self_ra - (MCOUNT_INSN_SIZE * insns);
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
|
|
|
|
|
/* Only trace if the calling function expects to */
|
|
|
|
|
if (!ftrace_graph_entry(&trace)) {
|
|
|
|
|
current->curr_ret_stack--;
|
MIPS, Tracing: Clean up prepare_ftrace_return()
The old prepare_ftrace_return() for MIPS is confused and have introduced
some problem. This patch cleans up the names of the arguments, variables
and related functions.
For MIPS, the 2nd argument of prepare_ftrace_return() is not really the
'selfpc' described in ftrace-design.txt but instead it is the self
return address. This did break the compatibility of the generic
interface but really reduced one unneeded calculation for to get the
current function name, the parent return address and the self return
address are enough, no need to tranform the self return address to the
self address.
But set_graph_function of function graph tracer is an exception, it does
need the 2nd argument of prepare_ftrace_return() as 'selfpc', for it
will use 'selfpc' to match user's configuration of function graph
entries, but in reality, it doesn't need the 'selfpc' but the recorded
ip address of the mcount calling site in the __mcount_loc section. So,
the 2nd argument of prepare_ftrace_return() is not important, the real
requirement is the right recorded ip address should be calculated and
assign to trace.func, this will be fixed in the next patches.
Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2007/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
2011-01-20 03:28:30 +08:00
|
|
|
*parent_ra_addr = old_parent_ra;
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
}
|
2009-11-20 20:34:36 +08:00
|
|
|
return;
|
|
|
|
|
out:
|
|
|
|
|
ftrace_graph_stop();
|
|
|
|
|
WARN_ON(1);
|
MIPS: Tracing: Add function graph tracer support for MIPS
The implementation of function graph tracer for MIPS is a little
different from X86.
in MIPS, gcc(with -pg) only transfer the caller's return address(at) and
the _mcount's return address(ra) to us.
For the kernel part without -mlong-calls:
move at, ra
jal _mcount
For the module part with -mlong-calls:
lui v1, hi16bit_of_mcount
addiu v1, v1, low16bit_of_mcount
move at, ra
jal _mcount
Without -mlong-calls,
if the function is a leaf, it will not save the return address(ra):
ffffffff80101298 <au1k_wait>:
ffffffff80101298: 67bdfff0 daddiu sp,sp,-16
ffffffff8010129c: ffbe0008 sd s8,8(sp)
ffffffff801012a0: 03a0f02d move s8,sp
ffffffff801012a4: 03e0082d move at,ra
ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff801012ac: 00020021 nop
so, we can hijack it directly in _mcount, but if the function is non-leaf, the
return address is saved in the stack.
ffffffff80133030 <copy_process>:
ffffffff80133030: 67bdff50 daddiu sp,sp,-176
ffffffff80133034: ffbe00a0 sd s8,160(sp)
ffffffff80133038: 03a0f02d move s8,sp
ffffffff8013303c: ffbf00a8 sd ra,168(sp)
ffffffff80133040: ffb70098 sd s7,152(sp)
ffffffff80133044: ffb60090 sd s6,144(sp)
ffffffff80133048: ffb50088 sd s5,136(sp)
ffffffff8013304c: ffb40080 sd s4,128(sp)
ffffffff80133050: ffb30078 sd s3,120(sp)
ffffffff80133054: ffb20070 sd s2,112(sp)
ffffffff80133058: ffb10068 sd s1,104(sp)
ffffffff8013305c: ffb00060 sd s0,96(sp)
ffffffff80133060: 03e0082d move at,ra
ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount>
ffffffff80133068: 00020021 nop
but we can not get the exact stack address(which saved ra) directly in
_mcount, we need to search the content of at register in the stack space
or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we
can not prove there is only a match in the stack space, so, we search
the text instead.
as we can see, if the first instruction above "move at, ra" is not a
store instruction, there should be a leaf function, so we hijack the at
register directly via putting &return_to_handler into it, otherwise, we
search the "s{d,w} ra, offset(sp)" instruction to get the stack offset,
and then the stack address. we use the above copy_process() as an
example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus
it with s8(fp), that is the stack address, we hijack the content via
writing the &return_to_handler in.
If with -mlong-calls, since there are two more instructions above "move
at, ra", so, we can move the pointer to the position above "lui v1,
hi16bit_of_mcount".
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-20 20:34:34 +08:00
|
|
|
}
|
2010-05-14 19:08:33 +08:00
|
|
|
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
|