netdev - Re: [PATCH bpf 1/3] ftrace: Fix function_graph tracer interaction with BPF trampoline

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Message-ID: <CAADnVQJVabzj-aytRnZrFCwRJAf+g_wZ-zWiO7D0bUm7UVpDQw@mail.gmail.com>
Date:   Tue, 10 Dec 2019 08:19:42 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Alexei Starovoitov <ast@...nel.org>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Daniel Borkmann <daniel@...earbox.net>,
        Steven Rostedt <rostedt@...dmis.org>, X86 ML <x86@...nel.org>,
        Network Development <netdev@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>, Kernel Team <kernel-team@...com>
Subject: Re: [PATCH bpf 1/3] ftrace: Fix function_graph tracer interaction
 with BPF trampoline

On Sun, Dec 8, 2019 at 4:03 PM Alexei Starovoitov <ast@...nel.org> wrote:
>
> Depending on type of BPF programs served by BPF trampoline it can call original
> function. In such case the trampoline will skip one stack frame while
> returning. That will confuse function_graph tracer and will cause crashes with
> bad RIP. Teach graph tracer to skip functions that have BPF trampoline attached.
>
> Signed-off-by: Alexei Starovoitov <ast@...nel.org>

Steven, please take a look.