This is a note to let you know that I've just added the patch titled
LoongArch: Fix callchain parse error with kernel tracepoint events again
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
loongarch-fix-callchain-parse-error-with-kernel-trac.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 02129730187195596c43810c2b126baf557538ab
Author: Huacai Chen <chenhuacai@xxxxxxxxxx>
Date: Tue May 14 12:24:18 2024 +0800
LoongArch: Fix callchain parse error with kernel tracepoint events again
[ Upstream commit d6af2c76399f98444a5b4de96baf4b362d9f102b ]
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@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/loongarch/include/asm/perf_event.h b/arch/loongarch/include/asm/perf_event.h
index 52b638059e40b..f948a0676daf8 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__ */
