On Thu, Jan 21, 2021 at 12:26 PM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> For very large ELF objects (with many sections), we could
> get special value SHN_XINDEX (65535) for elf object's string
> table index - e_shstrndx.
>
> Call elf_getshdrstrndx to get the proper string table index,
> instead of reading it directly from ELF header.
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
I've applied this patch to bpf-next, you don't need to re-send it in
the next version of this patch set.
> tools/lib/bpf/btf.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> index 9970a288dda5..d9c10830d749 100644
> --- a/tools/lib/bpf/btf.c
> +++ b/tools/lib/bpf/btf.c
> @@ -858,6 +858,7 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
> Elf_Scn *scn = NULL;
> Elf *elf = NULL;
> GElf_Ehdr ehdr;
> + size_t shstrndx;
>
> if (elf_version(EV_CURRENT) == EV_NONE) {
> pr_warn("failed to init libelf for %s\n", path);
> @@ -882,7 +883,14 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
> pr_warn("failed to get EHDR from %s\n", path);
> goto done;
> }
> - if (!elf_rawdata(elf_getscn(elf, ehdr.e_shstrndx), NULL)) {
> +
> + if (elf_getshdrstrndx(elf, &shstrndx)) {
> + pr_warn("failed to get section names section index for %s\n",
> + path);
> + goto done;
> + }
> +
> + if (!elf_rawdata(elf_getscn(elf, shstrndx), NULL)) {
> pr_warn("failed to get e_shstrndx from %s\n", path);
> goto done;
> }
> @@ -897,7 +905,7 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
> idx, path);
> goto done;
> }
> - name = elf_strptr(elf, ehdr.e_shstrndx, sh.sh_name);
> + name = elf_strptr(elf, shstrndx, sh.sh_name);
> if (!name) {
> pr_warn("failed to get section(%d) name from %s\n",
> idx, path);
> --
> 2.27.0
>
