Re: objtool crashes on clang output (drivers/hwmon/pmbus/adm1275.o)

From: Arnd Bergmann
Date: Fri Jul 12 2019 - 16:41:46 EST

On Fri, Jul 12, 2019 at 6:59 PM 'Nick Desaulniers' via Clang Built
Linux <clang-built-linux@xxxxxxxxxxxxxxxx> wrote:
> > The issue still needs to get fixed in clang regardless. There are other
> > noreturn functions in the kernel and this problem could easily pop back
> > up.
> Sure, thanks for the report. Arnd, can you help us get a more minimal
> test case to understand the issue better?

I reduced it to this testcase:

int a, b;
void __reiserfs_panic(int, ...) __attribute__((noreturn));
void balance_internal() {
if (a)
__reiserfs_panic(0, "", __func__, "", 2, __func__, a);
if (b)
__reiserfs_panic(0, "", __func__, "", 5, __func__, a, 0);

$ clang-8 -mstack-alignment=8 -S ibalance.c -Wall -Os -c
$ objtool orc generate ibalance.o
ibalance.o: warning: objtool: balance_internal()+0x61: stack state
mismatch: cfa1=7+8 cfa2=7+16