6.6-stable review patch. If anyone has any objections, please let me know.
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From: Huacai Chen chenhuacai@loongson.cn
[ 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 --- 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 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__ */