When GCC adds NOP padding between functions, those NOPs aren't
associated with a function symbol, which breaks objtool's detection of a
function falling through to another function.  Instead it shows
confusing errors like:

  drivers/mtd/chips/cfi_util.o: warning: objtool: cfi_qry_mode_on()+0x8b: 
return with modified stack frame
  drivers/mtd/chips/cfi_util.o: warning: objtool: cfi_qry_mode_on()+0x0: stack 
state mismatch: cfa1=-4-32 cfa2=7+8
  drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: 
fixup_use_fwh_lock()+0x8: unknown stack-related register move
  drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: 
fixup_use_fwh_lock()+0x0: stack state mismatch: cfa1=6+16 cfa2=7+8
  drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: do_otp_write()+0xa: 
unsupported stack pointer realignment
  drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: do_otp_write()+0x0: 
stack state mismatch: cfa1=-4-40 cfa2=7+8

Reported-by: kbuild test robot <fengguang...@intel.com>
Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
---
 tools/objtool/check.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 17375925e7aa..3dffeb944523 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1536,15 +1536,15 @@ static int validate_branch(struct objtool_file *file, 
struct instruction *first,
        while (1) {
                next_insn = next_insn_same_sec(file, insn);
 
-               if (file->c_file && insn->func) {
-                       if (func && func != insn->func) {
-                               WARN("%s() falls through to next function %s()",
-                                    func->name, insn->func->name);
-                               return 1;
-                       }
+
+               if (file->c_file && func && insn->func && func != insn->func) {
+                       WARN("%s() falls through to next function %s()",
+                            func->name, insn->func->name);
+                       return 1;
                }
 
-               func = insn->func;
+               if (insn->func)
+                       func = insn->func;
 
                if (func && insn->ignore) {
                        WARN_FUNC("BUG: why am I validating an ignored 
function?",
-- 
2.13.3

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