On Thu, Apr 30, 2015 at 02:58:52PM +0100, Hou Pengyang wrote: > For ARM & ARM64, when tracing with tracepoint events, the IP and cpsr are > set to 0, preventing the perf code parsing the callchain and resolving the > symbols correctly. > > ./perf record -e sched:sched_switch -g --call-graph dwarf ls > [ perf record: Captured and wrote 0.146 MB perf.data ] > ./perf report -f > Samples: 194 of event 'sched:sched_switch', Event count (approx.): 194 > Children Self Command Shared Object Symbol > 100.00% 100.00% ls [unknown] [.] 0000000000000000 > > The fix is to implement perf_arch_fetch_caller_regs for ARM64, which fills > several necessary registers used for callchain unwinding, including pc,sp, > fp and psr .
Thanks for the v2. > With this patch, callchain can be parsed correctly as follows: > > ...... > + 2.63% 0.00% ls [kernel.kallsyms] [k] vfs_symlink > + 2.63% 0.00% ls [kernel.kallsyms] [k] follow_down > + 2.63% 0.00% ls [kernel.kallsyms] [k] pfkey_get > + 2.63% 0.00% ls [kernel.kallsyms] [k] > do_execveat_common.isra.33 > - 2.63% 0.00% ls [kernel.kallsyms] [k] pfkey_send_policy_notify > pfkey_send_policy_notify > pfkey_get > v9fs_vfs_rename > page_follow_link_light > link_path_walk > el0_svc_naked > ....... > > Jean Pihet found this in ARM and come up with a patch: > http://thread.gmane.org/gmane.linux.kernel/1734283/focus=1734280 > > Signed-off-by: Hou Pengyang <[email protected]> > --- > arch/arm/include/asm/perf_event.h | 7 +++++++ > arch/arm64/include/asm/perf_event.h | 7 +++++++ > 2 files changed, 14 insertions(+) Can you split this into two patches, please? > diff --git a/arch/arm/include/asm/perf_event.h > b/arch/arm/include/asm/perf_event.h > index d9cf138..17705e2b 100644 > --- a/arch/arm/include/asm/perf_event.h > +++ b/arch/arm/include/asm/perf_event.h > @@ -19,4 +19,11 @@ extern unsigned long perf_misc_flags(struct pt_regs *regs); > #define perf_misc_flags(regs) perf_misc_flags(regs) > #endif > > +#define perf_arch_fetch_caller_regs(regs, __ip) { \ > + (regs)->ARM_pc = (__ip); \ > + (regs)->ARM_fp = (unsigned long) __builtin_frame_address(0); \ > + (regs)->ARM_sp = current_stack_pointer; \ > + (regs)->ARM_cpsr |= SYSTEM_MODE; \ You don't need to |= (just = is fine, perf memset's the thing to 0 anyway) and this should be SVC_MODE not SYSTEM_MODE. > +} > + > #endif /* __ARM_PERF_EVENT_H__ */ > diff --git a/arch/arm64/include/asm/perf_event.h > b/arch/arm64/include/asm/perf_event.h > index d26d1d5..e6911a4 100644 > --- a/arch/arm64/include/asm/perf_event.h > +++ b/arch/arm64/include/asm/perf_event.h > @@ -24,4 +24,11 @@ extern unsigned long perf_misc_flags(struct pt_regs *regs); > #define perf_misc_flags(regs) perf_misc_flags(regs) > #endif > > +#define perf_arch_fetch_caller_regs(regs, __ip) { \ > + (regs)->ARM_pc = (__ip); \ > + (regs)->ARM_fp = (unsigned long) __builtin_frame_address(0); \ > + (regs)->ARM_sp = current_stack_pointer; \ > + (regs)->ARM_cpsr |= PSR_MODE_EL1h; \ Similarly here, just use an assignment. Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
