netdev - Re: [PATCH v2 1/5] perf/x86: Always store regs->ip in perf_callchain

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Message-ID: <20190614205614.zr6awljx3qdg2fnb@ast-mbp.dhcp.thefacebook.com>
Date:   Fri, 14 Jun 2019 13:56:15 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     x86@...nel.org, Alexei Starovoitov <ast@...nel.org>,
        linux-kernel@...r.kernel.org,
        Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>,
        Song Liu <songliubraving@...com>,
        Kairui Song <kasong@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        David Laight <David.Laight@...LAB.COM>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH v2 1/5] perf/x86: Always store regs->ip in
 perf_callchain_kernel()

On Fri, Jun 14, 2019 at 12:56:40PM -0500, Josh Poimboeuf wrote:
> From: Song Liu <songliubraving@...com>
> 
> The stacktrace_map_raw_tp BPF selftest is failing because the RIP saved
> by perf_arch_fetch_caller_regs() isn't getting saved by
> perf_callchain_kernel().
> 
> This was broken by the following commit:
> 
>   d15d356887e7 ("perf/x86: Make perf callchains work without CONFIG_FRAME_POINTER")
> 
> With that change, when starting with non-HW regs, the unwinder starts
> with the current stack frame and unwinds until it passes up the frame
> which called perf_arch_fetch_caller_regs().  So regs->ip needs to be
> saved deliberately.
> 
> Fixes: d15d356887e7 ("perf/x86: Make perf callchains work without CONFIG_FRAME_POINTER")
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
> Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>

It's not cool to remove people's SOB.
It's Song's patch. His should be first and your second.