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| author | Hirokazu Takata <takata.hirokazu@renesas.com> | 2007-05-10 22:22:25 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-11 08:29:33 -0700 |
| commit | 43c09ce7927912c7867617cba0a265beea38a154 (patch) | |
| tree | 0b0a8b8e9a5f9b2e1fe7aa058378f23321f2a910 /include/asm-m32r/system.h | |
| parent | 44316634460a6b368ad3160da6cba3b4725a1433 (diff) | |
m32r: fix switch_to macro to push/pop frame pointer if needed
This patch fixes a rarely-happened but severe scheduling problem of
the recent m32r kernel of 2.6.17-rc3 or later.
In the following previous m32r patch, the switch_to macro was
modified not to do unnecessary push/pop operations for tuning.
> [PATCH] m32r: update switch_to macro for tuning
> 4127272c38619c56f0c1aa01d01c7bd757db70a1
In this modification, only 'lr' and 'sp' registers are push/pop'ed,
assuming that the m32r kernel is always compiled with
-fomit-frame-pointer option.
However, in 2.6 kernel, kernel/sched.c is irregularly compiled
with -fno-omit-frame-pointer if CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER
is not defined.
-- kernel/Makefile --
:
ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
# According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
# needed for x86 only. Why this used to be enabled for all architectures is beyond
# me. I suspect most platforms don't need this, but until we know that for sure
# I turn this off for IA-64 only. Andreas Schwab says it's also needed on m68k
# to get a correct value for the wait-channel (WCHAN in ps). --davidm
CFLAGS_sched.o := $(PROFILING) -fno-omit-frame-pointer
endif
:
---
Therefore, for the recent m32r kernel, we have to push/pop 'fp'
(frame pointer) if CONFIG_FRAME_POINTER is defined or
CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER is not defined.
Signed-off-by: Hitoshi Yamamoto <hitoshiy@linux-m32r.org>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/asm-m32r/system.h')
| -rw-r--r-- | include/asm-m32r/system.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/asm-m32r/system.h b/include/asm-m32r/system.h index f62f5c9abba6..b291b2f72954 100644 --- a/include/asm-m32r/system.h +++ b/include/asm-m32r/system.h @@ -21,12 +21,22 @@ * `next' and `prev' should be struct task_struct, but it isn't always defined */ +#if defined(CONFIG_FRAME_POINTER) || \ + !defined(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER) +#define M32R_PUSH_FP " push fp\n" +#define M32R_POP_FP " pop fp\n" +#else +#define M32R_PUSH_FP "" +#define M32R_POP_FP "" +#endif + #define switch_to(prev, next, last) do { \ __asm__ __volatile__ ( \ " seth lr, #high(1f) \n" \ " or3 lr, lr, #low(1f) \n" \ " st lr, @%4 ; store old LR \n" \ " ld lr, @%5 ; load new LR \n" \ + M32R_PUSH_FP \ " st sp, @%2 ; store old SP \n" \ " ld sp, @%3 ; load new SP \n" \ " push %1 ; store `prev' on new stack \n" \ @@ -34,6 +44,7 @@ " .fillinsn \n" \ "1: \n" \ " pop %0 ; restore `__last' from new stack \n" \ + M32R_POP_FP \ : "=r" (last) \ : "0" (prev), \ "r" (&(prev->thread.sp)), "r" (&(next->thread.sp)), \ |