5.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
commit dbf46008775516f7f25c95b7760041c286299783 upstream.
For stack-validation of a frame-pointer build, objtool validates that
every CALL instruction is preceded by a frame-setup. The new SRSO
return thunks violate this with their RSB stuffing trickery.
Extend the __fentry__ exception to also cover the embedded_insn case
used for this. This cures:
vmlinux.o: warning: objtool: srso_untrain_ret+0xd: call without frame pointer save/setup
Fixes: 4ae68b26c3ab ("objtool/x86: Fix SRSO mess")
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230816115921.GH980931@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
tools/objtool/check.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2079,12 +2079,17 @@ static int decode_sections(struct objtoo
return 0;
}
-static bool is_fentry_call(struct instruction *insn)
+static bool is_special_call(struct instruction *insn)
{
- if (insn->type == INSN_CALL &&
- insn->call_dest &&
- insn->call_dest->fentry)
- return true;
+ if (insn->type == INSN_CALL) {
+ struct symbol *dest = insn->call_dest;
+
+ if (!dest)
+ return false;
+
+ if (dest->fentry)
+ return true;
+ }
return false;
}
@@ -2958,7 +2963,7 @@ static int validate_branch(struct objtoo
if (ret)
return ret;
- if (!no_fp && func && !is_fentry_call(insn) &&
+ if (!no_fp && func && !is_special_call(insn) &&
!has_valid_stack_frame(&state)) {
WARN_FUNC("call without frame pointer save/setup",
sec, insn->offset);
