On Mon, Mar 15, 2010 at 04:46:15PM +1100, Paul Mackerras wrote: > 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. 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 <pau...@samba.org>
Cool! > --- > 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 > 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 > > #endif > > diff --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
