All exceptions must be taken in microMIPS mode, never in classic
MIPS mode or the kernel falls apart. A few NOP instructions are
used to maintain the correct alignment of microMIPS versions of
the exception vectors.
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Add two new macros for microMIPS. One checks if an exception was
taken in either microMIPS or classic MIPS mode. The other checks
if a microMIPS instruction is 16-bit or 32-bit in length.
[ralf@linux-mips.org: Removed unnecessary parenthesis as noted by
Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>]
Signed-off-by: Steven J. Hill <sjhill@mips.com>
Cc: linux-mips@linux-mips.org
Cc: cernekee@gmail.com
Cc: kevink@paralogos.com
Cc: ddaney.cavm@gmail.com
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Patchwork: https://patchwork.linux-mips.org/patch/4924/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
(cherry picked from commit 49df26472338b935fd5781bf94a77a88b148a716)
Commit 32a7ede (MIPS: dsp: Add assembler support for DSP ASEs) has
enabled the use of DSP ASE specific instructions such as rddsp and wrdsp
under the idea that all code path that will make use of these two
instructions are properly checking for cpu_has_dsp to ensure that the
particular CPU we are running on *actually* supports DSP ASE.
This commit actually causes the following oops on QEMU Malta emulating a
MIPS 24Kc without the DSP ASE implemented:
[ 7.960000] Reserved instruction in kernel
[ 7.960000] Cpu 0
[ 7.960000] $ 0 : 00000000 00000000 00000014 00000005
[ 7.960000] $ 4 : 8fc2de48 00000001 00000000 8f59ddb0
[ 7.960000] $ 8 : 8f5ceec4 00000018 00000c00 00800000
[ 7.960000] $12 : 00000100 00000200 00000000 00457b84
[ 7.960000] $16 : 00000000 8fc2ba78 8f4ec980 00000001
[ 7.960000] $20 : 80418f90 00000000 00000000 000002dd
[ 7.960000] $24 : 0000009c 7730d7b8
[ 7.960000] $28 : 8f59c000 8f59dd38 00000001 80104248
[ 7.960000] Hi : 0000001d
[ 7.960000] Lo : 0000000b
[ 7.960000] epc : 801041ec thread_saved_pc+0x2c/0x38
[ 7.960000] Not tainted
[ 7.960000] ra : 80104248 get_wchan+0x48/0xac
[ 7.960000] Status: 1000b703 KERNEL EXL IE
[ 7.960000] Cause : 10800028
[ 7.960000] PrId : 00019300 (MIPS 24Kc)
[ 7.960000] Modules linked in:
[ 7.960000] Process killall (pid: 1574, threadinfo=8f59c000,
task=8fd14558, tls=773aa440)
[ 7.960000] Stack : 8fc2ba78 8012b008 0000000c 0000001d 00000000
00000000 8f58a380
8f58a380 8fc2ba78 80202668 8f59de78 8f468600 8f59de28
801b2a3c 8f59df00 8f98ba20 74696e69
8f468600 8f59de28 801b7308 0081c007 00000000 00000000
00000000 00000000 00000000 00000000
00000000 8fc2bbb4 00000001 0000001d 0000000b 77f038cc
7fe80648 ffffffff ffffffff 00000000
00000001 0016e000 00000000 ...
[ 7.960000] Call Trace:
[ 7.960000] [<801041ec>] thread_saved_pc+0x2c/0x38
[ 7.960000] [<80104248>] get_wchan+0x48/0xac
The disassembly of thread_saved_pc points to the following:
000006d0 <thread_saved_pc>:
6d0: 8c820208 lw v0,520(a0)
6d4: 3c030000 lui v1,0x0
6d8: 24630000 addiu v1,v1,0
6dc: 10430008 beq v0,v1,700 <thread_saved_pc+0x30>
6e0: 00000000 nop
6e4: 3c020000 lui v0,0x0
6e8: 8c43000c lw v1,12(v0)
6ec: 04620004 bltzl v1,700 <thread_saved_pc+0x30>
6f0: 00001021 move v0,zero
6f4: 8c840200 lw a0,512(a0)
6f8: 00031080 sll v0,v1,0x2
6fc: 7c44100a lwx v0,a0(v0) <------------
700: 03e00008 jr ra
704: 00000000 nop
If we specifically disable -mdsp/-mdspr2 for arch/mips/kernel/process.o,
we get the following (non-crashing) assembly:
00000708 <thread_saved_pc>:
708: 8c820208 lw v0,520(a0)
70c: 3c030000 lui v1,0x0
710: 24630000 addiu v1,v1,0
714: 10430009 beq v0,v1,73c <thread_saved_pc+0x34>
718: 00000000 nop
71c: 3c020000 lui v0,0x0
720: 8c42000c lw v0,12(v0)
724: 04420005 bltzl v0,73c <thread_saved_pc+0x34>
728: 00001021 move v0,zero
72c: 8c830200 lw v1,512(a0)
730: 00021080 sll v0,v0,0x2
734: 00431021 addu v0,v0,v1
738: 8c420000 lw v0,0(v0)
73c: 03e00008 jr ra
740: 00000000 nop
The specific line that leads a different assembly being produced is:
unsigned long thread_saved_pc(struct task_struct *tsk)
...
return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; <---
The problem here is that the compiler was given the right to use DSP
instructions with the -mdsp / -mdspr2 command-line switches and
performed some optimization for us and used DSP ASE instructions where
we are not checking that the running CPU actually supports DSP ASE.
This patch fixes the issue by partially reverting commit 32a7ede for
arch/mips/kernel/Makefile in order to remove the -mdsp / -mdspr2
compiler command-line switches such that we are now guaranteed that the
compiler will not optimize using DSP ASE reserved instructions. We also
need to fixup the rddsp/wrdsp and m{t,h}{hi,lo}{0,1,2,3} macros in
arch/mips/include/asm/mipsregs.h to tell the assembler that we are going
to explicitely use DSP ASE reserved instructions. The comment in
arch/mips/kernel/Makefile is also updated to reflect that.
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Acked-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: blogic@openwrt.org
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The presence of the MIPS Virtualization Application-Specific Extension
is indicated by CP0_Config3[23]. Probe for this and report it in
/proc/cpuinfo.
Signed-off-by: David Daney <david.daney@cavium.com>
Patchwork: http://patchwork.linux-mips.org/patch/4904/
Signed-off-by: John Crispin <blogic@openwrt.org>
Simplify the DSP macros for vanilla (non-microMIPS) kernels and
toolchains that do not support the DSP ASEs.
Signed-off-by: Steven J. Hill <sjhill@mips.com>
Patchwork: http://patchwork.linux-mips.org/patch/4687/
Signed-off-by: John Crispin <blogic@openwrt.org>
Add macros to support the DSP ASE with microMIPS kernels when the
toolchain does not have support.
Signed-off-by: Steven J. Hill <sjhill@mips.com>
Patchwork: http://patchwork.linux-mips.org/patch/4686/
Signed-off-by: John Crispin <blogic@openwrt.org>
Newer toolchains support the DSP and DSP Rev2 instructions. This patch
performs a check for that support and adds compiler and assembler
flags for only the files that need use those instructions.
Signed-off-by: Steven J. Hill <sjhill@mips.com>
Acked-by: Florian Fainelli <florian@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/4752/
Signed-off-by: John Crispin <blogic@openwrt.org>
Having received another series of whitespace patches I decided to do this
once and for all rather than dealing with this kind of patches trickling
in forever.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
We need Huge TLBs for HUGETLB_PAGE, or the soon to follow
TRANSPARENT_HUGEPAGE. collect this information under a single Kconfig
symbol.
Signed-off-by: David Daney <david.daney@cavium.com>
[ralf@linux-mips.org: This patch really only detects the ASE and passes its
existence on to userland via /proc/cpuinfo. The DSP ASE Rev 2. adds new
resources but no resources that would need management by the kernel.]
Signed-off-by: Steven J. Hill <sjhill@mips.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/4165/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The PCI (Program Counter Interrupt) bit in the "cause" register
is mandatory for MIPS32R2 cores, but has also been added to some R1
cores (BMIPS5000). This change adds a cpu feature bit to make it
easier to check for and use this feature.
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/4106/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Originally both Read Inhibit (RI) and Execute Inhibit (XI) were
supported by the TLB only for a SmartMIPS core. The MIPSr3(TM)
Architecture now defines an optional feature to implement these
TLB bits separately. Support for one or both features can be
checked by looking at the Config3.RXI bit.
Signed-off-by: Steven J. Hill <sjhill@mips.com>
Acked-by: David Daney <david.daney@cavium.com>
In the FPU emulator code of the MIPS, the Cause bits of the FCSR register
are not currently writeable by the ctc1 instruction. In odd corner cases,
this can cause problems. For example, a case existed where a divide-by-zero
exception was generated by the FPU, and the signal handler attempted to
restore the FPU registers to their state before the exception occurred. In
this particular setup, writing the old value to the FCSR register would
cause another divide-by-zero exception to occur immediately. The solution
is to change the ctc1 instruction emulator code to allow the Cause bits of
the FCSR register to be writeable. This is the behaviour of the hardware
that the code is emulating.
This problem was found by Shane McDonald, but the credit for the fix goes
to Kevin Kissell. In Kevin's words:
I submit that the bug is indeed in that ctc_op: case of the emulator. The
Cause bits (17:12) are supposed to be writable by that instruction, but the
CTC1 emulation won't let them be updated by the instruction. I think that
actually if you just completely removed lines 387-388 [...] things would
work a good deal better. At least, it would be a more accurate emulation of
the architecturally defined FPU. If I wanted to be really, really pedantic
(which I sometimes do), I'd also protect the reserved bits that aren't
necessarily writable.
Signed-off-by: Shane McDonald <mcdonald.shane@gmail.com>
To: anemo@mba.ocn.ne.jp
To: kevink@paralogos.com
To: sshtylyov@mvista.com
Patchwork: http://patchwork.linux-mips.org/patch/1205/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
---
For processors that have more than 64 TLBs, we need to decode both
config1 and config4 to determine the total number TLBs.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/866/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The MIPS processor is limited to 64 external interrupt sources. Using a
greater number without IRQ sharing requires reading platform-specific
registers. On such platforms, reading the IntCtl register to determine
which interrupt corresponds to a timer interrupt will not work.
On MIPSR2 systems there is a solution - the TI bit in the Cause register,
specifically indicates that a timer interrupt has occured. This patch uses
that bit to detect interrupts for MIPSR2 processors, which may be expected
to work regardless of how the timer interrupt may be routed in the hardware.
Signed-off-by: David VomLehn (dvomlehn@cisco.com)
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/804/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Beyond the requirements of the architecture standard Cavium also supports
8k and 32k pages.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: David Daney <ddaney@caviumnetworks.com>
Gas from binutils 2.19 fails to compile some cop1 instructions with
-march=octeon. Since the cop1 instructions are present in mips1, use
that arch instead. This will be fixed in binutils 2.20.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
We already have sufficient infrastructure to support VR5500 and VR5500A
series processors. Here's a Makefile support to make it selectable by
ports, and enable it for NEC EMMA2RH Markeins board.
This patch also fixes a confused target help, and adds 1Gb PageMask bits
supported by VR5500 and its variants.
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Steven J. Hill