From 0fb93615830ee95b32ab19b843f75ca6917ab6a7 Mon Sep 17 00:00:00 2001 From: Huacai Chen Date: Tue, 14 May 2024 12:24:18 +0800 Subject: [PATCH] LoongArch: Fix callchain parse error with kernel tracepoint events again BugLink: https://bugs.launchpad.net/bugs/2073603 [ 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 Signed-off-by: Sasha Levin Signed-off-by: Portia Stephens Signed-off-by: Roxana Nicolescu --- 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__ */