6.8-stable review patch. If anyone has any objections, please let me know.
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From: Huacai Chen chenhuacai@loongson.cn
commit d3119bc985fb645ad3b2a9cf9952c1d56d9daaa3 upstream.
In order to fix perf's callchain parse error for LoongArch, we implement perf_arch_fetch_caller_regs() which fills several necessary registers used for callchain unwinding, including sp, fp, and era. This is similar to the following commits.
commit b3eac0265bf6: ("arm: perf: Fix callchain parse error with kernel tracepoint events")
commit 5b09a094f2fb: ("arm64: perf: Fix callchain parse error with kernel tracepoint events")
commit 9a7e8ec0d4cc: ("riscv: perf: Fix callchain parse error with kernel tracepoint events")
Test with commands:
perf record -e sched:sched_switch -g --call-graph dwarf perf report
Without this patch:
Children Self Command Shared Object Symbol ........ ........ ............. ................. ....................
43.41% 43.41% swapper [unknown] [k] 0000000000000000
10.94% 10.94% loong-container [unknown] [k] 0000000000000000 | |--5.98%--0x12006ba38 | |--2.56%--0x12006bb84 | --2.40%--0x12006b6b8
With this patch, callchain can be parsed correctly:
Children Self Command Shared Object Symbol ........ ........ ............. ................. ....................
47.57% 47.57% swapper [kernel.vmlinux] [k] __schedule | ---__schedule
26.76% 26.76% loong-container [kernel.vmlinux] [k] __schedule | |--13.78%--0x12006ba38 | | | |--9.19%--__schedule | | | --4.59%--handle_syscall | do_syscall | sys_futex | do_futex | futex_wait | futex_wait_queue_me | hrtimer_start_range_ns | __schedule | |--8.38%--0x12006bb84 | handle_syscall | do_syscall | sys_epoll_pwait | do_epoll_wait | schedule_hrtimeout_range_clock | hrtimer_start_range_ns | __schedule | --4.59%--0x12006b6b8 handle_syscall do_syscall sys_nanosleep hrtimer_nanosleep do_nanosleep hrtimer_start_range_ns __schedule
Cc: stable@vger.kernel.org Fixes: b37042b2bb7cd751f0 ("LoongArch: Add perf events support") Reported-by: Youling Tang tangyouling@kylinos.cn Suggested-by: Youling Tang tangyouling@kylinos.cn Signed-off-by: Huacai Chen chenhuacai@loongson.cn Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/loongarch/include/asm/perf_event.h | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/arch/loongarch/include/asm/perf_event.h +++ b/arch/loongarch/include/asm/perf_event.h @@ -7,6 +7,14 @@ #ifndef __LOONGARCH_PERF_EVENT_H__ #define __LOONGARCH_PERF_EVENT_H__
+#include <asm/ptrace.h> + #define perf_arch_bpf_user_pt_regs(regs) (struct user_pt_regs *)regs
+#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); \ +} + #endif /* __LOONGARCH_PERF_EVENT_H__ */