Messages in this thread Patch in this message | | | From | Hou Pengyang <> | Subject | [PATCH v5] arm64: perf: Fix callchain parse error with kernel tracepoint events | Date | Sun, 10 May 2015 11:07:40 +0000 |
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For ARM64, when tracing with tracepoint events, the IP and pstate 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 spsr .
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 .......
Signed-off-by: Hou Pengyang <houpengyang@huawei.com> Acked-by: Will Deacon <will.deacon@arm.com> --- arch/arm64/include/asm/perf_event.h | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/arm64/include/asm/perf_event.h b/arch/arm64/include/asm/perf_event.h index d26d1d5..6471773 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)->pc = (__ip); \ + (regs)->regs[29] = (unsigned long) __builtin_frame_address(0); \ + (regs)->sp = current_stack_pointer; \ + (regs)->pstate = PSR_MODE_EL1h; \ +} + #endif -- 1.8.5.2
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