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| author | Jiri Olsa <jolsa@kernel.org> | 2025-11-04 22:54:02 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2025-11-05 17:05:19 -0800 |
| commit | 6d08340d1e354787d6c65a8c3cdd4d41ffb8a5ed (patch) | |
| tree | 995518d05b22aa08a1c428f99f773e889ecf67ea | |
| parent | 44e8f13f07cfaa978c19fb4d66904f65905c7259 (diff) | |
Revert "perf/x86: Always store regs->ip in perf_callchain_kernel()"
This reverts commit 83f44ae0f8afcc9da659799db8693f74847e66b3.
Currently we store initial stacktrace entry twice for non-HW ot_regs, which
means callers that fail perf_hw_regs(regs) condition in perf_callchain_kernel.
It's easy to reproduce this bpftrace:
# bpftrace -e 'tracepoint:sched:sched_process_exec { print(kstack()); }'
Attaching 1 probe...
bprm_execve+1767
bprm_execve+1767
do_execveat_common.isra.0+425
__x64_sys_execve+56
do_syscall_64+133
entry_SYSCALL_64_after_hwframe+118
When perf_callchain_kernel calls unwind_start with first_frame, AFAICS
we do not skip regs->ip, but it's added as part of the unwind process.
Hence reverting the extra perf_callchain_store for non-hw regs leg.
I was not able to bisect this, so I'm not really sure why this was needed
in v5.2 and why it's not working anymore, but I could see double entries
as far as v5.10.
I did the test for both ORC and framepointer unwind with and without the
this fix and except for the initial entry the stacktraces are the same.
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20251104215405.168643-2-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
| -rw-r--r-- | arch/x86/events/core.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 745caa6c15a3..fa6c47b50989 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2789,13 +2789,13 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re return; } - if (perf_callchain_store(entry, regs->ip)) - return; - - if (perf_hw_regs(regs)) + if (perf_hw_regs(regs)) { + if (perf_callchain_store(entry, regs->ip)) + return; unwind_start(&state, current, regs, NULL); - else + } else { unwind_start(&state, current, NULL, (void *)regs->sp); + } for (; !unwind_done(&state); unwind_next_frame(&state)) { addr = unwind_get_return_address(&state); |