On Fri, Feb 15, 2019 at 01:53:51PM -0800, Song Liu wrote:
> This patch enables perf-record to save btf information as headers to
> perf.data A new header type HEADER_BTF is introduced for this data.
> 
> Signed-off-by: Song Liu <songliubrav...@fb.com>
> ---
>  tools/perf/util/header.c | 99 +++++++++++++++++++++++++++++++++++++++-
>  tools/perf/util/header.h |  1 +
>  2 files changed, 99 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index 0889ad797940..2de4f4e9b590 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -1127,6 +1127,45 @@ static int write_bpf_prog_info(struct feat_fd *ff,
>       return ret;
>  }
>  
> +static int write_btf(struct feat_fd *ff,
> +                  struct perf_evlist *evlist __maybe_unused)
> +{
> +     struct perf_env *env = &ff->ph->env;
> +     struct rb_root *root;
> +     struct rb_node *next;
> +     u32 count = 0;
> +     int ret;
> +
> +     down_read(&env->bpf_progs.bpf_info_lock);
> +
> +     root = &env->bpf_progs.btfs;
> +     next = rb_first(root);
> +     while (next) {
> +             ++count;
> +             next = rb_next(next);
> +     }
> +
> +     ret = do_write(ff, &count, sizeof(count));
> +
> +     if (ret < 0)
> +             goto out;
> +
> +     next = rb_first(root);
> +     while (next) {
> +             struct btf_node *node;
> +
> +             node = rb_entry(next, struct btf_node, rb_node);
> +             next = rb_next(&node->rb_node);
> +             ret = do_write(ff, node,
> +                            sizeof(struct btf_node) + node->data_size);

hm, you write the whole struct btf_node with struct rb_node? why?

thanks,
jirka

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