[PATCH bpf-next 3/3] libbpf: Use string table index from index table if needed
From: Jiri Olsa <jolsa@kernel.org>
Date: 2021-01-21 20:35:06
Also in:
netdev
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [library] (libbpf), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
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@kernel.org> --- 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