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authorPeter Zijlstra <peterz@infradead.org>2023-08-16 13:59:21 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-08-26 13:27:00 +0200
commit4da4aae04b7f3d5ba4345a75f92de00a54644f11 (patch)
tree616e3621ca433a674ecc42fee485e97832220266 /tools
parentc8b056a3b4ebb33adbb873cab152ed499d1a1dcb (diff)
downloadlinux-4da4aae04b7f3d5ba4345a75f92de00a54644f11.tar.gz
objtool/x86: Fixup frame-pointer vs rethunk
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@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20230816115921.GH980931@hirez.programming.kicks-ass.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'tools')
-rw-r--r--tools/objtool/check.c17
1 files changed, 11 insertions, 6 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 7c4e61cbefaa..913bd361c368 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2450,12 +2450,17 @@ static int decode_sections(struct objtool_file *file)
 	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;
 }
@@ -3448,7 +3453,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 			if (ret)
 				return ret;
 
-			if (opts.stackval && func && !is_fentry_call(insn) &&
+			if (opts.stackval && func && !is_special_call(insn) &&
 			    !has_valid_stack_frame(&state)) {
 				WARN_FUNC("call without frame pointer save/setup",
 					  sec, insn->offset);