From: Peter Zijlstra <peterz@infradead.org>
To: Song Liu <songliubraving@fb.com>
Cc: linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
kernel-team@fb.com, Kairui Song <kasong@redhat.com>,
Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH] perf/x86: always include regs->ip in callchain
Date: Wed, 22 May 2019 15:58:50 +0200 [thread overview]
Message-ID: <20190522135850.GB16275@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20190521204813.1167784-1-songliubraving@fb.com>
On Tue, May 21, 2019 at 01:48:13PM -0700, Song Liu wrote:
> Commit d15d356887e7 removes regs->ip for !perf_hw_regs(regs) case. This
> breaks tests like test_stacktrace_map from selftests/bpf/tests_prog.
That test is broken by something else; just the one entry is wrong too.
That said, yes the patch below is actually correct, but the above
description is misleading at best.
> This patch adds regs->ip back.
>
> Fixes: d15d356887e7 ("perf/x86: Make perf callchains work without CONFIG_FRAME_POINTER")
> Cc: Kairui Song <kasong@redhat.com>
> Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
> Signed-off-by: Song Liu <songliubraving@fb.com>
> ---
> 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
>
next prev parent reply other threads:[~2019-05-22 13:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-21 20:48 [PATCH] perf/x86: always include regs->ip in callchain Song Liu
2019-05-22 13:58 ` Peter Zijlstra [this message]
2019-05-22 16:12 ` Song Liu
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