On Thu, Mar 16, 2023 at 10:02 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> Use build id from file object in stackmap if it's available.
>
> The file's f_build_id is available (for CONFIG_FILE_BUILD_ID option)
> when the file is mmap-ed, so it will be available (if present) when
> used by stackmap.
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
LGTM.
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> kernel/bpf/stackmap.c | 24 +++++++++++++++++++++++-
> 1 file changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
> index 0f1d8dced933..14d27bd83081 100644
> --- a/kernel/bpf/stackmap.c
> +++ b/kernel/bpf/stackmap.c
> @@ -124,6 +124,28 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
> return ERR_PTR(err);
> }
>
> +#ifdef CONFIG_FILE_BUILD_ID
> +static int vma_get_build_id(struct vm_area_struct *vma, unsigned char *build_id)
> +{
> + struct build_id *bid;
> +
> + if (!vma->vm_file)
> + return -EINVAL;
> + bid = vma->vm_file->f_build_id;
> + if (IS_ERR_OR_NULL(bid))
> + return bid ? PTR_ERR(bid) : -ENOENT;
> + if (bid->sz > BUILD_ID_SIZE_MAX)
> + return -EINVAL;
> + memcpy(build_id, bid->data, bid->sz);
> + return 0;
> +}
> +#else
> +static int vma_get_build_id(struct vm_area_struct *vma, unsigned char *build_id)
> +{
> + return build_id_parse(vma, build_id, NULL);
> +}
> +#endif
> +
> static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
> u64 *ips, u32 trace_nr, bool user)
> {
> @@ -156,7 +178,7 @@ 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]);
> - if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) {
> + if (!vma || vma_get_build_id(vma, id_offs[i].build_id)) {
> /* per entry fall back to ips */
> id_offs[i].status = BPF_STACK_BUILD_ID_IP;
> id_offs[i].ip = ips[i];
> --
> 2.39.2
>
