linux-kernel - [PATCH v2 15/22] objtool: Change dead_end

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Message-Id: <9e6679610768fb6e6c51dca23f7d4d0c03b0c910.1563413318.git.jpoimboe@redhat.com>
Date:   Wed, 17 Jul 2019 20:36:50 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Arnd Bergmann <arnd@...db.de>, Jann Horn <jannh@...gle.com>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: [PATCH v2 15/22] objtool: Change dead_end_function() to return boolean

dead_end_function() can no longer return an error.  Simplify its
interface by making it return boolean.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Tested-by: Nick Desaulniers <ndesaulniers@...gle.com>
---
 tools/objtool/check.c | 36 ++++++++++++++----------------------
 1 file changed, 14 insertions(+), 22 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 16454cbca679..970dfeac841d 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -105,14 +105,9 @@ static struct instruction *next_insn_same_func(struct objtool_file *file,
  *
  * For local functions, we have to detect them manually by simply looking for
  * the lack of a return instruction.
- *
- * Returns:
- *  -1: error
- *   0: no dead end
- *   1: dead end
  */
-static int __dead_end_function(struct objtool_file *file, struct symbol *func,
-			       int recursion)
+static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
+				int recursion)
 {
 	int i;
 	struct instruction *insn;
@@ -139,29 +134,29 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func,
 	};
 
 	if (func->bind == STB_WEAK)
-		return 0;
+		return false;
 
 	if (func->bind == STB_GLOBAL)
 		for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
 			if (!strcmp(func->name, global_noreturns[i]))
-				return 1;
+				return true;
 
 	if (!func->len)
-		return 0;
+		return false;
 
 	insn = find_insn(file, func->sec, func->offset);
 	if (!insn->func)
-		return 0;
+		return false;
 
 	func_for_each_insn_all(file, func, insn) {
 		empty = false;
 
 		if (insn->type == INSN_RETURN)
-			return 0;
+			return false;
 	}
 
 	if (empty)
-		return 0;
+		return false;
 
 	/*
 	 * A function can have a sibling call instead of a return.  In that
@@ -174,7 +169,7 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func,
 
 			if (!dest)
 				/* sibling call to another file */
-				return 0;
+				return false;
 
 			if (dest->func && dest->func->pfunc != insn->func->pfunc) {
 
@@ -186,7 +181,7 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func,
 					 * This is a very rare case.  It means
 					 * they aren't dead ends.
 					 */
-					return 0;
+					return false;
 				}
 
 				return __dead_end_function(file, dest->func,
@@ -196,13 +191,13 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func,
 
 		if (insn->type == INSN_JUMP_DYNAMIC && list_empty(&insn->alts))
 			/* sibling call */
-			return 0;
+			return false;
 	}
 
-	return 1;
+	return true;
 }
 
-static int dead_end_function(struct objtool_file *file, struct symbol *func)
+static bool dead_end_function(struct objtool_file *file, struct symbol *func)
 {
 	return __dead_end_function(file, func, 0);
 }
@@ -2080,11 +2075,8 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 				if (is_fentry_call(insn))
 					break;
 
-				ret = dead_end_function(file, insn->call_dest);
-				if (ret == 1)
+				if (dead_end_function(file, insn->call_dest))
 					return 0;
-				if (ret == -1)
-					return 1;
 			}
 
 			if (!no_fp && func && !has_valid_stack_frame(&state)) {
-- 
2.20.1