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| author | Paul Mackerras <paulus@samba.org> | 2010-03-18 16:05:13 +1100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-03-18 06:48:29 +0100 |
| commit | 9eff26ea48bfbe2885b158742a7512a097ec911b (patch) | |
| tree | a914f959b78bdf4ee9eca897a743d727c27faf4f | |
| parent | 00909e955125e90a6ebb34671c56c4c851e62951 (diff) | |
| download | linux-stable-9eff26ea48bfbe2885b158742a7512a097ec911b.tar.gz linux-stable-9eff26ea48bfbe2885b158742a7512a097ec911b.tar.bz2 linux-stable-9eff26ea48bfbe2885b158742a7512a097ec911b.zip | |
powerpc/perf_events: Fix call-graph recording, add perf_arch_fetch_caller_regs
This implements a powerpc version of perf_arch_fetch_caller_regs
to get correct call-graphs.
It's implemented in assembly because that way we can be sure there isn't
a stack frame for perf_arch_fetch_caller_regs. If it was in C, gcc might
or might not create a stack frame for it, which would affect the number
of levels we have to skip.
With this, we see results from perf record -e lock:lock_acquire like
this:
# Samples: 24878
#
# Overhead Command Shared Object Symbol
# ........ .............. ................. ......
#
14.99% perf [kernel.kallsyms] [k] ._raw_spin_lock
|
--- ._raw_spin_lock
|
|--25.00%-- .alloc_fd
| (nil)
| |
| |--50.00%-- .anon_inode_getfd
| | .sys_perf_event_open
| | syscall_exit
| | syscall
| | create_counter
| | __cmd_record
| | run_builtin
| | main
| | 0xfd2e704
| | 0xfd2e8c0
| | (nil)
... etc.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: anton@samba.org
Cc: linuxppc-dev@ozlabs.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100318050513.GA6575@drongo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | arch/powerpc/include/asm/asm-compat.h | 2 | ||||
| -rw-r--r-- | arch/powerpc/kernel/misc.S | 28 |
2 files changed, 30 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/asm-compat.h b/arch/powerpc/include/asm/asm-compat.h index c1b475a941eb..a9b91ed3d4b9 100644 --- a/arch/powerpc/include/asm/asm-compat.h +++ b/arch/powerpc/include/asm/asm-compat.h @@ -28,6 +28,7 @@ #define PPC_LLARX(t, a, b, eh) PPC_LDARX(t, a, b, eh) #define PPC_STLCX stringify_in_c(stdcx.) #define PPC_CNTLZL stringify_in_c(cntlzd) +#define PPC_LR_STKOFF 16 /* Move to CR, single-entry optimized version. Only available * on POWER4 and later. @@ -51,6 +52,7 @@ #define PPC_STLCX stringify_in_c(stwcx.) #define PPC_CNTLZL stringify_in_c(cntlzw) #define PPC_MTOCRF stringify_in_c(mtcrf) +#define PPC_LR_STKOFF 4 #endif diff --git a/arch/powerpc/kernel/misc.S b/arch/powerpc/kernel/misc.S index 2d29752cbe16..b485a87c94e1 100644 --- a/arch/powerpc/kernel/misc.S +++ b/arch/powerpc/kernel/misc.S @@ -127,3 +127,31 @@ _GLOBAL(__setup_cpu_power7) _GLOBAL(__restore_cpu_power7) /* place holder */ blr + +#ifdef CONFIG_EVENT_TRACING +/* + * Get a minimal set of registers for our caller's nth caller. + * r3 = regs pointer, r5 = n. + * + * We only get R1 (stack pointer), NIP (next instruction pointer) + * and LR (link register). These are all we can get in the + * general case without doing complicated stack unwinding, but + * fortunately they are enough to do a stack backtrace, which + * is all we need them for. + */ +_GLOBAL(perf_arch_fetch_caller_regs) + mr r6,r1 + cmpwi r5,0 + mflr r4 + ble 2f + mtctr r5 +1: PPC_LL r6,0(r6) + bdnz 1b + PPC_LL r4,PPC_LR_STKOFF(r6) +2: PPC_LL r7,0(r6) + PPC_LL r7,PPC_LR_STKOFF(r7) + PPC_STL r6,GPR1-STACK_FRAME_OVERHEAD(r3) + PPC_STL r4,_NIP-STACK_FRAME_OVERHEAD(r3) + PPC_STL r7,_LINK-STACK_FRAME_OVERHEAD(r3) + blr +#endif /* CONFIG_EVENT_TRACING */ |