On Thu, May 23, 2019 at 1:34 PM Song Liu wrote:
>
> Commit d15d356887e7 removes regs->ip for !perf_hw_regs(regs) case. This
> patch adds regs->ip back.
>
> Fixes: d15d356887e7 ("perf/x86: Make perf callchains work without
> CONFIG_FRAME_POINTER")
> Cc: Kairui Song
> Cc: Peter Zijlstra (Intel)
> Signed-off-by: Song Liu
> ---
> arch/x86/events/core.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
> index f315425d8468..7b8a9eb4d5fd 100644
> --- a/arch/x86/events/core.c
> +++ b/arch/x86/events/core.c
> @@ -2402,9 +2402,9 @@ 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_callchain_store(entry, regs->ip))
> - return;
> unwind_start(&state, current, regs, NULL);
> } else {
> unwind_start(&state, current, NULL, (void *)regs->sp);
> --
> 2.17.1
>
Hi, this will make !perf_hw_regs(regs) case print a double first level
stack trace, which is wrong. And the actual problem that unwinder give
empty calltrace in bpf is still not fixed.
--
Best Regards,
Kairui Song
