objtool: Use sh_info to find the base for .rela sections

ELF doesn't require .rela section names to match the base section. Use
the section index in sh_info to find the section instead of looking it
up by name.

LLD, for example, generates a .rela section that doesn't match the base
section name when we merge sections in a linker script for a binary
compiled with -ffunction-sections.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index f953d3a15612a8f88675444e4b8d20d53a44ab81..5bc259c9d892c9fab97d40c2a7699d57463d4e83 100644 (file)
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -508,7 +508,7 @@ static int read_relas(struct elf *elf)
                if (sec->sh.sh_type != SHT_RELA)
                        continue;
 
-               sec->base = find_section_by_name(elf, sec->name + 5);
+               sec->base = find_section_by_index(elf, sec->sh.sh_info);
                if (!sec->base) {
                        WARN("can't find base section for rela section %s",
                             sec->name);