This is a note to let you know that I've just added the patch titled
objtool: Teach get_alt_entry() about more relocation types
to the 5.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
objtool-teach-get_alt_entry-about-more-relocation-ty.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e79c2ee117c37790efc73000de29f1d2a5a5ee1f
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Thu Sep 30 12:43:10 2021 +0200
objtool: Teach get_alt_entry() about more relocation types
[ Upstream commit 24ff652573754fe4c03213ebd26b17e86842feb3 ]
Occasionally objtool encounters symbol (as opposed to section)
relocations in .altinstructions. Typically they are the alternatives
written by elf_add_alternative() as encountered on a noinstr
validation run on vmlinux after having already ran objtool on the
individual .o files.
Basically this is the counterpart of commit 44f6a7c0755d ("objtool:
Fix seg fault with Clang non-section symbols"), because when these new
assemblers (binutils now also does this) strip the section symbols,
elf_add_reloc_to_insn() is forced to emit symbol based relocations.
As such, teach get_alt_entry() about different relocation types.
Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls")
Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Reported-by: Borislav Petkov <bp@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Link: https://lore.kernel.org/r/YVWUvknIEVNkPvnP@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index bc925cf19e2d..f58ecc50fb10 100644
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -58,6 +58,24 @@ void __weak arch_handle_alternative(unsigned short feature, struct special_alt *
{
}
+static bool reloc2sec_off(struct reloc *reloc, struct section **sec, unsigned long *off)
+{
+ switch (reloc->sym->type) {
+ case STT_FUNC:
+ *sec = reloc->sym->sec;
+ *off = reloc->sym->offset + reloc->addend;
+ return true;
+
+ case STT_SECTION:
+ *sec = reloc->sym->sec;
+ *off = reloc->addend;
+ return true;
+
+ default:
+ return false;
+ }
+}
+
static int get_alt_entry(struct elf *elf, struct special_entry *entry,
struct section *sec, int idx,
struct special_alt *alt)
@@ -91,15 +109,12 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry,
WARN_FUNC("can't find orig reloc", sec, offset + entry->orig);
return -1;
}
- if (orig_reloc->sym->type != STT_SECTION) {
- WARN_FUNC("don't know how to handle non-section reloc symbol %s",
+ if (!reloc2sec_off(orig_reloc, &alt->orig_sec, &alt->orig_off)) {
+ WARN_FUNC("don't know how to handle reloc symbol type: %s",
sec, offset + entry->orig, orig_reloc->sym->name);
return -1;
}
- alt->orig_sec = orig_reloc->sym->sec;
- alt->orig_off = orig_reloc->addend;
-
if (!entry->group || alt->new_len) {
new_reloc = find_reloc_by_dest(elf, sec, offset + entry->new);
if (!new_reloc) {
@@ -116,8 +131,11 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry,
if (arch_is_retpoline(new_reloc->sym))
return 1;
- alt->new_sec = new_reloc->sym->sec;
- alt->new_off = (unsigned int)new_reloc->addend;
+ if (!reloc2sec_off(new_reloc, &alt->new_sec, &alt->new_off)) {
+ WARN_FUNC("don't know how to handle reloc symbol type: %s",
+ sec, offset + entry->new, new_reloc->sym->name);
+ return -1;
+ }
/* _ASM_EXTABLE_EX hack */
if (alt->new_off >= 0x7ffffff0)
