With commit d3119bc985fb645 ("LoongArch: Fix callchain parse error with
kernel tracepoint events"), perf can parse kernel callchain, but not
complete and sometimes maybe error. The reason is LoongArch's unwinders
(guess, prologue and orc) don't really need fp (i.e., regs[22]), and
they use sp (i.e., regs[3]) as the frame address rather than the current
stack pointer.
Fix that by removing the assignment of regs[22], and instead assign the
__builtin_frame_address(0) to regs[3].
Without fix:
Children Self Command Shared Object Symbol
........ ........ ............. ................. ................
33.91% 33.91% swapper [kernel.vmlinux] [k] __schedule
|
|--33.04%--__schedule
|
--0.87%--__arch_cpu_idle
__schedule
With this fix:
Children Self Command Shared Object Symbol
........ ........ ............. ................. ................
31.16% 31.16% swapper [kernel.vmlinux] [k] __schedule
|
|--20.63%--smpboot_entry
| cpu_startup_entry
| schedule_idle
| __schedule
|
--10.53%--start_kernel
cpu_startup_entry
schedule_idle
__schedule
Fixes: d3119bc985fb645 ("LoongArch: Fix callchain parse error with kernel tracepoint events")
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
arch/loongarch/include/asm/perf_event.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/loongarch/include/asm/perf_event.h b/arch/loongarch/include/asm/perf_event.h
index 52b638059e40..f948a0676daf 100644
--- a/arch/loongarch/include/asm/perf_event.h
+++ b/arch/loongarch/include/asm/perf_event.h
@@ -13,8 +13,7 @@
#define perf_arch_fetch_caller_regs(regs, __ip) { \
(regs)->csr_era = (__ip); \
- (regs)->regs[3] = current_stack_pointer; \
- (regs)->regs[22] = (unsigned long) __builtin_frame_address(0); \
+ (regs)->regs[3] = (unsigned long) __builtin_frame_address(0); \
}
#endif /* __LOONGARCH_PERF_EVENT_H__ */
--
2.43.0