From: Huacai Chen chenhuacai@loongson.cn
stable inclusion from stable-v6.6.33 commit 379ec9d95c896c0a02c00f20f0564939b41ae471 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAD6H2
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ 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@loongson.cn Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Wang Hai wanghai38@huawei.com --- 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__ */