[PATCH AUTOSEL 5.6 20/38] objtool: Support Clang non-section symbols in ORC dump

Sasha Levin
2020-04-24T12:23:05Z

From: Josh Poimboeuf <jpoimboe@redhat.com>

[ Upstream commit 8782e7cab51b6bf01a5a86471dd82228af1ac185 ]

Historically, the relocation symbols for ORC entries have only been
section symbols:

.text+0: sp:sp+8 bp:(und) type:call end:0

However, the Clang assembler is aggressive about stripping section
symbols. In that case we will need to use function symbols:

freezing_slow_path+0: sp:sp+8 bp:(und) type:call end:0

In preparation for the generation of such entries in "objtool orc
generate", add support for reading them in "objtool orc dump".

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/b811b5eb1a42602c3b523576dc5efab9ad1c174d.1585761021.git.jpoimboe@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/objtool/orc_dump.c | 44 ++++++++++++++++++++++++----------------
1 file changed, 27 insertions(+), 17 deletions(-)

diff --git a/tools/objtool/orc_dump.c b/tools/objtool/orc_dump.c
index 13ccf775a83a4..ba4cbb1cdd632 100644
--- a/tools/objtool/orc_dump.c
+++ b/tools/objtool/orc_dump.c
@@ -66,7 +66,7 @@ int orc_dump(const char *_objname)
char *name;
size_t nr_sections;
Elf64_Addr orc_ip_addr = 0;
- size_t shstrtab_idx;
+ size_t shstrtab_idx, strtab_idx = 0;
Elf *elf;
Elf_Scn *scn;
GElf_Shdr sh;
@@ -127,6 +127,8 @@ int orc_dump(const char *_objname)

if (!strcmp(name, ".symtab")) {
symtab = data;
+ } else if (!strcmp(name, ".strtab")) {
+ strtab_idx = i;
} else if (!strcmp(name, ".orc_unwind")) {
orc = data->d_buf;
orc_size = sh.sh_size;
@@ -138,7 +140,7 @@ int orc_dump(const char *_objname)
}
}

- if (!symtab || !orc || !orc_ip)
+ if (!symtab || !strtab_idx || !orc || !orc_ip)
return 0;

if (orc_size % sizeof(*orc) != 0) {
@@ -159,21 +161,29 @@ int orc_dump(const char *_objname)
return -1;
}

- scn = elf_getscn(elf, sym.st_shndx);
- if (!scn) {
- WARN_ELF("elf_getscn");
- return -1;
- }
-
- if (!gelf_getshdr(scn, &sh)) {
- WARN_ELF("gelf_getshdr");
- return -1;
- }
-
- name = elf_strptr(elf, shstrtab_idx, sh.sh_name);
- if (!name || !*name) {
- WARN_ELF("elf_strptr");
- return -1;
+ if (GELF_ST_TYPE(sym.st_info) == STT_SECTION) {
+ scn = elf_getscn(elf, sym.st_shndx);
+ if (!scn) {
+ WARN_ELF("elf_getscn");
+ return -1;
+ }
+
+ if (!gelf_getshdr(scn, &sh)) {
+ WARN_ELF("gelf_getshdr");
+ return -1;
+ }
+
+ name = elf_strptr(elf, shstrtab_idx, sh.sh_name);
+ if (!name) {
+ WARN_ELF("elf_strptr");
+ return -1;
+ }
+ } else {
+ name = elf_strptr(elf, strtab_idx, sym.st_name);
+ if (!name) {
+ WARN_ELF("elf_strptr");
+ return -1;
+ }
}

printf("%s+%llx:", name, (unsigned long long)rela.r_addend);
--
2.20.1