@@ -1904,18 +1904,32 @@ static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder)
goto out;
}
- data = elf_getdata(scn, 0);
- if (!data) {
- elf_error("Failed to get ELF section(%d) data", i);
- goto out;
- }
-
if (shdr.sh_type == SHT_SYMTAB) {
+ data = elf_getdata(scn, 0);
+ if (!data) {
+ elf_error("Failed to get ELF section(%d) data", i);
+ goto out;
+ }
+
symbols_shndx = i;
symscn = scn;
symbols = data;
strtabidx = shdr.sh_link;
} else if (!strcmp(secname, BTF_IDS_SECTION)) {
+ /* .BTF_ids section consists of uint32_t elements,
+ * and thus might need byte order conversion.
+ * However, it has type PROGBITS, hence elf_getdata()
+ * won't automatically do the conversion.
+ * Use elf_getdata_rawchunk() instead,
+ * ELF_T_WORD tells it to do the necessary conversion.
+ */
+ data = elf_getdata_rawchunk(elf, shdr.sh_offset, shdr.sh_size, ELF_T_WORD);
+ if (!data) {
+ elf_error("Failed to get %s ELF section(%d) data",
+ BTF_IDS_SECTION, i);
+ goto out;
+ }
+
idlist_shndx = i;
idlist_addr = shdr.sh_addr;
idlist = data;
btf_encoder__tag_kfuncs() reads .BTF_ids section to identify a set of kfuncs present in the ELF file being processed. This section consists of: - arrays of uint32_t elements; - arrays of records with the following structure: struct btf_id_and_flag { uint32_t id; uint32_t flags; }; When endianness of a binary operated by pahole differs from the host system's endianness, these fields require byte-swapping before use. Currently, this byte-swapping does not occur, resulting in kfuncs not being marked with declaration tags. This commit resolves the issue by using elf_getdata_rawchunk() function to read .BTF_ids section data. When called with ELF_T_WORD as 'type' parameter it does necessary byte order conversion (only if host and elf endianness do not match). Cc: Alan Maguire <alan.maguire@oracle.com> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Daniel Xu <dxu@dxuuu.xyz> Cc: Jiri Olsa <olsajiri@gmail.com> Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com> Cc: Vadim Fedorenko <vadfed@meta.com> Fixes: 72e88f29c6f7 ("pahole: Inject kfunc decl tags into BTF") Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> --- btf_encoder.c | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-)