Impact: speed up
The return to handler portion of the function graph tracer should only
need to save the return values. The caller already saved off the
registers that the callee can modify. The returning function already
saved the registers it modified. When we call our own trace function
it too will save the registers that the callee must restore.
There's no reason to save off anything more that the registers used
to return the values.
Note, I did a complete kernel build with this modification and the
function graph tracer running on x86_64.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: mark save_paranoid as non-kprobe-able code
This appears to be necessary as the function gets called from
kprobes-unsafe exception handling stubs (i.e. which themselves
live in .kprobes.text).
Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <49B8F44F.76E4.0078.0@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
These got left in needlessly when ret_from_fork got simplified.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <49B8F355.76E4.0078.0@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch allocates a system interrupt vector for various platform
specific uses.
Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: john stultz <johnstul@us.ibm.com>
LKML-Reference: <20090304185605.GA24419@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
native_usergs_sysret64 is described as
extern void native_usergs_sysret64(void)
so lets add ENDPROC here
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: heukelum@fastmail.fm
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In general, the only definitions that assembly files can use
are in _types.S headers (where available), so convert them.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Impact: Fixes dumpstack and KDB on 64 bits
This re-adds the old stack pointer to the top of the irqstack to help
with unwinding. It was removed in commit d99015b1ab
as part of the save_args out-of-line work.
Both dumpstack and KDB require this information.
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Impact: Fix latent bug
The clobber is trying to say that anything except RDI is available for
clobbering, but actually clobbers everything. This hasn't mattered
because the clobbers were basically ignored, but subsequent patches
will rely on them.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Make X86 SGI Ultraviolet support configurable. Saves about 13K of text size
on my modest config.
text data bss dec hex filename
6770537 1158680 694356 8623573 8395d5 vmlinux
6757492 1157664 694228 8609384 835e68 vmlinux.nouv
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
tj: * in asm-offsets_64.c, pda.h inclusion shouldn't be removed as pda
is still referenced in the file
* s/oldrsp/old_rsp/
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Also clean up PER_CPU_VAR usage in xen-asm_64.S
tj: * remove now unused stack_thread_info()
* s/kernelstack/kernel_stack/
* added FIXME comment in xen-asm_64.S
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Move the irqstackptr variable from the PDA to per-cpu. Make the
stacks themselves per-cpu, removing some specific allocation code.
Add a seperate flag (is_boot_cpu) to simplify the per-cpu boot
adjustments.
tj: * sprinkle some underbars around.
* irq_stack_ptr is not used till traps_init(), no reason to
initialize it early. On SMP, just leaving it NULL till proper
initialization in setup_per_cpu_areas() works. Dropped
is_boot_cpu and early irq_stack_ptr initialization.
* do DECLARE/DEFINE_PER_CPU(char[IRQ_STACK_SIZE], irq_stack)
instead of (char, irq_stack[IRQ_STACK_SIZE]).
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Now that pda is allocated as part of percpu, percpu doesn't need to be
accessed through pda. Unify x86_64 SMP percpu access with x86_32 SMP
one. Other than the segment register, operand size and the base of
percpu symbols, they behave identical now.
This patch replaces now unnecessary pda->data_offset with a dummy
field which is necessary to keep stack_canary at its place. This
patch also moves per_cpu_offset initialization out of init_gdt() into
setup_per_cpu_areas(). Note that this change also necessitates
explicit per_cpu_offset initializations in voyager_smp.c.
With this change, x86_OP_percpu()'s are as efficient on x86_64 as on
x86_32 and also x86_64 can use assembly PER_CPU macros.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: micro-optimization
The patch below removes an unnecessary locked instruction from
switch_to(). TIF_FORK is only ever set in copy_thread() on initial
process creation, and gets cleared during the first scheduling of the
process. As such, it is safe to use an unlocked test for the flag
within switch_to().
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (241 commits)
sched, trace: update trace_sched_wakeup()
tracing/ftrace: don't trace on early stage of a secondary cpu boot, v3
Revert "x86: disable X86_PTRACE_BTS"
ring-buffer: prevent false positive warning
ring-buffer: fix dangling commit race
ftrace: enable format arguments checking
x86, bts: memory accounting
x86, bts: add fork and exit handling
ftrace: introduce tracing_reset_online_cpus() helper
tracing: fix warnings in kernel/trace/trace_sched_switch.c
tracing: fix warning in kernel/trace/trace.c
tracing/ring-buffer: remove unused ring_buffer size
trace: fix task state printout
ftrace: add not to regex on filtering functions
trace: better use of stack_trace_enabled for boot up code
trace: add a way to enable or disable the stack tracer
x86: entry_64 - introduce FTRACE_ frame macro v2
tracing/ftrace: add the printk-msg-only option
tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp()
x86, bts: correctly report invalid bts records
...
Fixed up trivial conflict in scripts/recordmcount.pl due to SH bits
being already partly merged by the SH merge.
Impact: clean up
Itroduce MCOUNT_SAVE/RESTORE_FRAME which allow us to
save a number of lines on source level.
Also fix a comment in ftrace.h.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: feature, let entry function decide to trace or not
This patch lets the graph tracer entry function decide if the tracing
should be done at the end as well. This requires all function graph
entry functions return 1 if it should trace, or 0 if the return should
not be traced.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: consistency change for function graph
This patch makes function graph record the mcount caller address
the same way the function tracer does.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: extend and enable the function graph tracer to 64-bit x86
This patch implements the support for function graph tracer under x86-64.
Both static and dynamic tracing are supported.
This causes some small CPP conditional asm on arch/x86/kernel/ftrace.c I
wanted to use probe_kernel_read/write to make the return address
saving/patching code more generic but it causes tracing recursion.
That would be perhaps useful to implement a notrace version of these
function for other archs ports.
Note that arch/x86/process_64.c is not traced, as in X86-32. I first
thought __switch_to() was responsible of crashes during tracing because I
believed current task were changed inside but that's actually not the
case (actually yes, but not the "current" pointer).
So I will have to investigate to find the functions that harm here, to
enable tracing of the other functions inside (but there is no issue at
this time, while process_64.c stays out of -pg flags).
A little possible race condition is fixed inside this patch too. When the
tracer allocate a return stack dynamically, the current depth is not
initialized before but after. An interrupt could occur at this time and,
after seeing that the return stack is allocated, the tracer could try to
trace it with a random uninitialized depth. It's a prevention, even if I
hadn't problems with it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tim Bird <tim.bird@am.sony.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: remove dead code
If we take a closer look at the rff_trace/rff_action ret_from_fork code,
we have to realize that it does all the wrong things: for example it
checks the TIF flag - while later on jumping back to the ret-from-syscall
path - duplicating the check needlessly.
But checking for _TIF_SYSCALL_TRACE is completely unnecessary here because
we clear that flag for every freshly forked task. So the whole "tracing"
code here, for which there is a out of line jump optimization that makes
it even harder to read, is in reality completely dead code ...
Reported-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Cyrill Gorcunov <gorcunov@gmail.com>
We merge this branch because x86/debug touches code that we started
cleaning up in x86/irq. The two branches started out independent,
but as unexpected amount of activity went into x86/irq, they became
dependent. Resolve that by this cross-merge.
child_rip is called not by its name but indirectly
rather so make it global and aligned.
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Acked-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clean up assembly macros and annotations - with some object impact
entry_64.S is the only user of KPROBE_ENTRY / KPROBE_END on
x86_64. This patch reorders entry_64.S and explicitly generates
a separate section for functions that need the protection. The
generated code before and after the patch is equal.
Implicitly changing sections in assembly files makes it more
difficult to follow why the assembler is doing certain things.
For example,
.p2align 5
KPROBE_ENTRY(...)
was not doing what you would expect. Other section changes
(__ex_table, .fixup, .init.rodata) are done explicitly already.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Acked-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: improve backtrace quality
avoid the confusion in call trace because of the lack of padding at the
tail of function.
When do_exit gets called, the return address behind call instruction is
pushed into stack. If something get wrong in do_exit, for x86_64, the
entry "kernel_execve +0x00/0xXX" rather than "child_rip +0xYY/0xZZ" is
in the call trace.
That looks confusing, so add a u2d to make the return address still part
of the original call site. (This also catches any instances of us returning
from that function somehow.)
Signed-off-by: jia zhang <jia.zhang2008@gmail.com>
Acked-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: move some code out of .kprobes.text
KPROBE_ENTRY switches code generation to .kprobes.text, and KPROBE_END
uses .popsection to get back to the previous section (.text, normally).
Also replace ENDPROC by END, for consistency.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup of entry_64.S
Except for the order and the place of the functions, this
patch should not change the generated code.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Move recently introduced dwarf2 macros to dwarf2.h file.
It allow us to not duplicate them in assembly files.
Active usage of _cfi macros don't make assembly files
more obvious to understand but we already have a lot of
macros there which requires to search the definitions
of them *anyway*. But at least it make every cfi usage
one line shorter.
Also some code alignment is done.
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix bootup crash
Even though it tested fine for me, there was still a bug in the
first patch: I have overlooked a call to ptregscall_common. This
patch fixes that, I think, but the code is never executed for
me while running a debian install... (I tested this by putting
an "1:jmp 1b" in there.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
DISABLE_INTERRUPTS(CLBR_NONE)/TRACE_IRQS_OFF is now always
executed just before paranoid_exit. Move it there.
Split out paranoidzeroentry, paranoiderrorentry, and
paranoidzeroentry_ist to get more readable macro's.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, shrink kernel image size
Also expand the paranoid_exit0 macro into nmi_exit inside the
nmi stub in the case of enabled irq-tracing.
This gives a few hundred bytes code size reduction.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
The save_rest function completes a partial stack frame for use
by the PTREGSCALL macro. This also avoids the indirect call in
PTREGSCALLs.
This adds the macro movq_cfi_restore to hide the CFI_RESTORE
annotation when restoring a register from the stack frame.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: build fix
The break builds with older binutils (2.16.1):
arch/x86/kernel/entry_64.S: Assembler messages:
arch/x86/kernel/entry_64.S:282: Error: too many positional arguments
arch/x86/kernel/entry_64.S:283: Error: too many positional arguments
arch/x86/kernel/entry_64.S:284: Error: too many positional arguments
arch/x86/kernel/entry_64.S:285: Error: too many positional arguments
arch/x86/kernel/entry_64.S:286: Error: too many positional arguments
arch/x86/kernel/entry_64.S:287: Error: too many positional arguments
arch/x86/kernel/entry_64.S:288: Error: too many positional arguments
arch/x86/kernel/entry_64.S:289: Error: too many positional arguments
arch/x86/kernel/entry_64.S:290: Error: too many positional arguments
Took some time to figure out the detail that GAS chokes on: it's
negative offsets. Rearrange the calculations to make sure we never
go negative.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This add-on patch to x86: move entry_64.S register saving out
of the macros visually cleans up the appearance of the code by
introducing some basic helper macro's. It also adds some cfi
annotations which were missing.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Here is a combined patch that moves "save_args" out-of-line for
the interrupt macro and moves "error_entry" mostly out-of-line
for the zeroentry and errorentry macros.
The save_args function becomes really straightforward and easy
to understand, with the possible exception of the stack switch
code, which now needs to copy the return address of to the
calling function. Normal interrupts arrive with ((~vector)-0x80)
on the stack, which gets adjusted in common_interrupt:
<common_interrupt>:
(5) addq $0xffffffffffffff80,(%rsp) /* -> ~(vector) */
(4) sub $0x50,%rsp /* space for registers */
(5) callq ffffffff80211290 <save_args>
(5) callq ffffffff80214290 <do_IRQ>
<ret_from_intr>:
...
An apic interrupt stub now look like this:
<thermal_interrupt>:
(5) pushq $0xffffffffffffff05 /* ~(vector) */
(4) sub $0x50,%rsp /* space for registers */
(5) callq ffffffff80211290 <save_args>
(5) callq ffffffff80212b8f <smp_thermal_interrupt>
(5) jmpq ffffffff80211f93 <ret_from_intr>
Similarly the exception handler register saving function becomes
simpler, without the need of any parameter shuffling. The stub
for an exception without errorcode looks like this:
<overflow>:
(6) callq *0x1cad12(%rip) # ffffffff803dd448 <pv_irq_ops+0x38>
(2) pushq $0xffffffffffffffff /* no syscall */
(4) sub $0x78,%rsp /* space for registers */
(5) callq ffffffff8030e3b0 <error_entry>
(3) mov %rsp,%rdi /* pt_regs pointer */
(2) xor %esi,%esi /* no error code */
(5) callq ffffffff80213446 <do_overflow>
(5) jmpq ffffffff8030e460 <error_exit>
And one for an exception with errorcode like this:
<segment_not_present>:
(6) callq *0x1cab92(%rip) # ffffffff803dd448 <pv_irq_ops+0x38>
(4) sub $0x78,%rsp /* space for registers */
(5) callq ffffffff8030e3b0 <error_entry>
(3) mov %rsp,%rdi /* pt_regs pointer */
(5) mov 0x78(%rsp),%rsi /* load error code */
(9) movq $0xffffffffffffffff,0x78(%rsp) /* no syscall */
(5) callq ffffffff80213209 <do_segment_not_present>
(5) jmpq ffffffff8030e460 <error_exit>
Unfortunately, this last type is more than 32 bytes. But the total space
savings due to this patch is about 2500 bytes on an smp-configuration,
and I think the code is clearer than it was before. The tested kernels
were non-paravirt ones (i.e., without the indirect call at the top of
the exception handlers).
Anyhow, I tested this patch on top of a recent -tip. The machine
was an 2x4-core Xeon at 2333MHz. Measured where the delays between
(almost-)adjacent rdtsc instructions. The graphs show how much
time is spent outside of the program as a function of the measured
delay. The area under the graph represents the total time spent
outside the program. Eight instances of the rdtsctest were
started, each pinned to a single cpu. The histogams are added.
For each kernel two measurements were done: one in mostly idle
condition, the other while running "bonnie++ -f", bound to cpu 0.
Each measurement took 40 minutes runtime. See the attached graphs
for the results. The graphs overlap almost everywhere, but there
are small differences.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
All blame goes to: color white,red "[^[:graph:]]+$"
in .nanorc ;).
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: Fix interrupt via the apicinterrupt macro
Checkin 939b787130 changed the
"interrupt" macro, but the "interrupt" macro is also invoked
indirectly from the "apicinterrupt" macro.
The "apicinterrupt" macro probably should have its own collection of
systematic stubs for the same reason the main IRQ code does; as is it
is a huge amount of replicated code.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Older versions of gas don't implement the C-style != operator, they
instead want the Pascal-style <> operator. Change != to <> so we
don't break compilation with those old versions of gas.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Move the IRQ stub generation to assembly to simplify it and for
consistency with 32 bits. Doing it in a C file with asm() statements
doesn't help clarity, and it prevents some optimizations.
Shrink the IRQ stubs down to just over four bytes per (we fit seven
into a 32-byte chunk.) This shrinks the total icache consumption of
the IRQ stubs down to an even kilobyte, if all of them are in active
use.
The downside is that we end up with a double jump, which could have a
negative effect on some pipelines. The double jump is always inside
the same cacheline on any modern chips.
To get the most effect, cache-align the IRQ stubs.
This makes the 64-bit code match changes already done to the 32-bit
code, and should open up irqinit*.c for unification.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Impact: quick start and stop of function tracer
This patch adds a way to disable the function tracer quickly without
the need to run kstop_machine. It adds a new variable called
function_trace_stop which will stop the calls to functions from mcount
when set. This is just an on/off switch and does not handle recursion
like preempt_disable().
It's main purpose is to help other tracers/debuggers start and stop tracing
fuctions without the need to call kstop_machine.
The config option HAVE_FUNCTION_TRACE_MCOUNT_TEST is added for archs
that implement the testing of the function_trace_stop in the mcount
arch dependent code. Otherwise, the test is done in the C code.
x86 is the only arch at the moment that supports this.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Steven Rostedt