objtool: Do frame pointer check before dead end check

Even calls to __noreturn functions need the frame pointer setup first.
Such functions often dump the stack.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/aed62fbd60e239280218be623f751a433658e896.1563413318.git.jpoimboe@redhat.com

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index d9d1c9b..0d2a8e5 100644 (file)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -133,6 +133,9 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
                "rewind_stack_do_exit",
        };
 
+       if (!func)
+               return false;
+
        if (func->bind == STB_WEAK)
                return false;
 
@@ -2071,19 +2074,16 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
                        if (ret)
                                return ret;
 
-                       if (insn->type == INSN_CALL) {
-                               if (is_fentry_call(insn))
-                                       break;
-
-                               if (dead_end_function(file, insn->call_dest))
-                                       return 0;
-                       }
-
-                       if (!no_fp && func && !has_valid_stack_frame(&state)) {
+                       if (!no_fp && func && !is_fentry_call(insn) &&
+                           !has_valid_stack_frame(&state)) {
                                WARN_FUNC("call without frame pointer save/setup",
                                          sec, insn->offset);
                                return 1;
                        }
+
+                       if (dead_end_function(file, insn->call_dest))
+                               return 0;
+
                        break;
 
                case INSN_JUMP_CONDITIONAL: