Re: [linux-next:master 12681/13861] drivers/i2c/i2c-core-base.o: warning: objtool: __i2c_transfer+0x120: stack state mismatch: reg1[24]=-1+0 reg2[24]=-2-24

[Huacai Chen <chenhuacai@kernel.org>]

On Thu, Apr 3, 2025 at 5:36 PM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
> On 04/02/2025 03:45 AM, Josh Poimboeuf wrote:
> > On Tue, Apr 01, 2025 at 12:38:37PM +0800, Philip Li wrote:
> >> On Tue, Apr 01, 2025 at 10:44:57AM +0800, kernel test robot wrote:
> >>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> >>> head:   405e2241def89c88f008dcb899eb5b6d4be8b43c
> >>> commit: 9016dad4dca4bbe61c48ffd5a273cad980caa0d1 [12681/13861] loongarch: add support for suppressing warning backtraces
> >>> config: loongarch-randconfig-001-20250401 (https://download.01.org/0day-ci/archive/20250401/202504011011.jyZ6NtXx-lkp@intel.com/config)
> >>> compiler: loongarch64-linux-gcc (GCC) 14.2.0
> >>> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250401/202504011011.jyZ6NtXx-lkp@intel.com/reproduce)
> >>>
> >>> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> >>> the same patch/commit), kindly add following tags
> >>> | Reported-by: kernel test robot <lkp@intel.com>
> >>> | Closes: https://lore.kernel.org/oe-kbuild-all/202504011011.jyZ6NtXx-lkp@intel.com/
> >>>
> >>> All warnings (new ones prefixed by >>):
> >>>
> >>>>> drivers/i2c/i2c-core-base.o: warning: objtool: __i2c_transfer+0x120: stack state mismatch: reg1[24]=-1+0 reg2[24]=-2-24
> >
> > Tiezhu, this looks like a loongarch GCC bug with asm goto, or am I
> > confused?  See analysis below.
>
> This is related with GCC optimization "-fshrink-wrap" which is default y
> on LoongArch, use "-fno-shrink-wrap" can avoid such issues, like this:
>
> ---8<---
>
> diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> index 0304eabbe606..2d5529322357 100644
> --- a/arch/loongarch/Makefile
> +++ b/arch/loongarch/Makefile
> @@ -106,6 +106,7 @@ KBUILD_CFLAGS                       +=
> -mannotate-tablejump
>   else
>   KBUILD_CFLAGS                  += -fno-jump-tables # keep
> compatibility with older compilers
>   endif
> +KBUILD_CFLAGS                  += -fno-shrink-wrap
>   endif
>
>   KBUILD_RUSTFLAGS               +=
> --target=loongarch64-unknown-none-softfloat -Ccode-model=small
>
> If you are OK with this change, I will send a formal patch after the
> merge window.
Is this the same problem solved by the commit below?

https://web.git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=objtool/urgent&id=7c977393b8277ed319e92e4b598b26598c9d30c0

Huacai

>
> Thanks,
> Tiezhu
>
>