Merge tag 'objtool-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool fix from Thomas Gleixner:
 "A single fix for objtool to prevent an infinite loop in the
  jump table search which can be triggered when building the
  kernel with '-ffunction-sections'"

* tag 'objtool-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Fix infinite loop in find_jump_table()

tools/objtool/check.c

@@ -72,6 +72,17 @@ static struct instruction *next_insn_same_func(struct objtool_file *file,
 	return find_insn(file, func->cfunc->sec, func->cfunc->offset);
 }
 
+static struct instruction *prev_insn_same_sym(struct objtool_file *file,
+					       struct instruction *insn)
+{
+	struct instruction *prev = list_prev_entry(insn, list);
+
+	if (&prev->list != &file->insn_list && prev->func == insn->func)
+		return prev;
+
+	return NULL;
+}
+
 #define func_for_each_insn(file, func, insn)				\
 	for (insn = find_insn(file, func->sec, func->offset);		\
 	     insn;							\
@@ -1050,8 +1061,8 @@ static struct rela *find_jump_table(struct objtool_file *file,
 	 * it.
 	 */
 	for (;
-	     &insn->list != &file->insn_list && insn->func && insn->func->pfunc == func;
-	     insn = insn->first_jump_src ?: list_prev_entry(insn, list)) {
+	     insn && insn->func && insn->func->pfunc == func;
+	     insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
 
 		if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
 			break;