Re: [PATCH RFC 2/5] bpf: Use file object build id in stackmap

Jiri Olsa
2023-02-09T13:19:17Z

On Wed, Feb 08, 2023 at 11:23:13PM -0800, Hao Luo wrote:
> 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?

that might simplify also the perf code.. we might need to rename
it though.. maybe build_id_read(vma,...), I'll check

thanks,
jirka

>
> > 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
> >