Re: [PATCH] powerpc/perf_events: Implement perf_arch_fetch_caller_regs for powerpc
From: Michael Neuling <hidden>
Date: 2010-03-15 17:37:01
Also in:
lkml
This implements a powerpc version of perf_arch_fetch_caller_regs. 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.
Should we put this comment in the code as well? Mikey
quoted hunk ↗ jump to hunk
It's not ifdef'd because it is only 14 instructions long. 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 <redacted> --- arch/powerpc/include/asm/asm-compat.h | 2 ++ arch/powerpc/kernel/misc.S | 20 ++++++++++++++++++++ 2 files changed, 22 insertions(+)diff --git a/arch/powerpc/include/asm/asm-compat.h b/arch/powerpc/include/asm
/asm-compat.h
quoted hunk ↗ jump to hunk
index c1b475a..a9b91ed 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 #endifdiff --git a/arch/powerpc/kernel/misc.S b/arch/powerpc/kernel/misc.S index 2d29752..4459500 100644 --- a/arch/powerpc/kernel/misc.S +++ b/arch/powerpc/kernel/misc.S@@ -127,3 +127,23 @@ _GLOBAL(__setup_cpu_power7) _GLOBAL(__restore_cpu_power7) /* place holder */ blr + +/* + * Get a minimal set of registers for our caller's nth caller. + * r3 = regs pointer, r5 = n. + */ +_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_______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev