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References: <20230201135737.800527-1-jolsa@kernel.org> <20230201135737.800527-3-jolsa@kernel.org>
In-Reply-To: <20230201135737.800527-3-jolsa@kernel.org>
From:   Hao Luo <haoluo@google.com>
Date:   Wed, 8 Feb 2023 23:23:13 -0800
Message-ID: <CA+khW7iGj=Y3NVxc9Y-MnwmPxCz5jHDmSfW-S6KS9Hko=jgJOg@mail.gmail.com>
Subject: Re: [PATCH RFC 2/5] bpf: Use file object build id in stackmap
To:     Jiri Olsa <jolsa@kernel.org>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        bpf@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-perf-users@vger.kernel.org, Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@chromium.org>,
        Stanislav Fomichev <sdf@google.com>,
        Daniel Borkmann <daniel@iogearbox.net>
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On Wed, Feb 1, 2023 at 5:58 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Use build id from file object in stackmap if it's available.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---

Can we insert the lookup from vma->vm_file in build_id_parse() rather
than its callers?

>  kernel/bpf/stackmap.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
> index aecea7451b61..944cb260a42c 100644
> --- a/kernel/bpf/stackmap.c
> +++ b/kernel/bpf/stackmap.c
> @@ -156,7 +156,15 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
>                         goto build_id_valid;
>                 }
>                 vma = find_vma(current->mm, ips[i]);
> +#ifdef CONFIG_FILE_BUILD_ID
> +               if (vma && vma->vm_file && vma->vm_file->f_bid) {
> +                       memcpy(id_offs[i].build_id,
> +                              vma->vm_file->f_bid->data,
> +                              vma->vm_file->f_bid->sz);
> +               } else {
> +#else
>                 if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) {
> +#endif
>                         /* per entry fall back to ips */
>                         id_offs[i].status = BPF_STACK_BUILD_ID_IP;
>                         id_offs[i].ip = ips[i];
> --
> 2.39.1
>