On Fri, Feb 8, 2019 at 9:13 AM Yonghong Song <y...@fb.com> wrote:
>
>
>
> On 2/7/19 6:55 PM, Andrii Nakryiko wrote:
> > This patch changes struct btf_ext to retain original data in sequential
> > block of memory, which makes it possible to expose
> > btf_ext__get_raw_data() interface, that's similar to
> > btf__get_raw_data(), allowing users of libbpf to get access to raw
> > representation of .BTF.ext section.
> >
> > Signed-off-by: Andrii Nakryiko <andr...@fb.com>
> > ---
> > tools/lib/bpf/btf.c | 85 +++++++++++++++++++++-------------------
> > tools/lib/bpf/btf.h | 2 +
> > tools/lib/bpf/libbpf.map | 1 +
> > 3 files changed, 47 insertions(+), 41 deletions(-)
> >
> > diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> > index 8730f6c3be9e..c87cc3d71b9f 100644
> > --- a/tools/lib/bpf/btf.c
> > +++ b/tools/lib/bpf/btf.c
> > @@ -41,9 +41,8 @@ struct btf {
> >
> > struct btf_ext_info {
> > /*
> > - * info points to a deep copy of the individual info section
> > - * (e.g. func_info and line_info) from the .BTF.ext.
> > - * It does not include the __u32 rec_size.
> > + * info points to the individual info section (e.g. func_info and
> > + * line_info) from the .BTF.ext. It does not include the __u32
> > rec_size.
> > */
> > void *info;
> > __u32 rec_size;
> > @@ -51,8 +50,13 @@ struct btf_ext_info {
> > };
> >
> > struct btf_ext {
> > + union {
> > + struct btf_ext_header *hdr;
> > + void *data;
> > + };
> > struct btf_ext_info func_info;
> > struct btf_ext_info line_info;
> > + __u32 data_size;
> > };
> >
> > struct btf_ext_info_sec {
> > @@ -603,19 +607,13 @@ struct btf_ext_sec_copy_param {
> > };
> >
> > static int btf_ext_copy_info(struct btf_ext *btf_ext,
> > - __u8 *data, __u32 data_size,
> > struct btf_ext_sec_copy_param *ext_sec)
>
> Overall looks good. Since we do not really "copy" info any more,
> rather we try to "setup" info based on btf_ext. Maybe changing
> all function and structure names with "_copy_" to "_setup_"?
Makes sense, will update.
>
> > {
> > - const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
> > const struct btf_ext_info_sec *sinfo;
> > struct btf_ext_info *ext_info;
> > __u32 info_left, record_size;
> > /* The start of the info sec (including the __u32 record_size). */
> > - const void *info;
> > -
> > - /* data and data_size do not include btf_ext_header from now on */
> > - data = data + hdr->hdr_len;
> > - data_size -= hdr->hdr_len;
> > + void *info;
> [...]
