Re: [linux-next:master 8173/8441] include/linux/list.h:53:13: warning: '__preserve_most__' calling convention is not supported for this target

[Marco Elver <elver@google.com>]

On Wed, Aug 09, 2023 at 06:27PM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   21ef7b1e17d039053edaeaf41142423810572741
> commit: fee8feb67f0b2954eb7a2a259122e43a15cf3a52 [8173/8441] list_debug: introduce CONFIG_DEBUG_LIST_MINIMAL
> config: hexagon-randconfig-r041-20230808 (https://download.01.org/0day-ci/archive/20230809/202308091820.0dPY7D6f-lkp@intel.com/config)
> compiler: clang version 15.0.7 (https://github.com/llvm/llvm-project.git 8dfdcc7b7bf66834a761bd8de445840ef68e4d1a)
> reproduce: (https://download.01.org/0day-ci/archive/20230809/202308091820.0dPY7D6f-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/202308091820.0dPY7D6f-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
>    In file included from arch/hexagon/kernel/asm-offsets.c:12:
>    In file included from include/linux/compat.h:14:
>    In file included from include/linux/sem.h:5:
>    In file included from include/uapi/linux/sem.h:5:
>    In file included from include/linux/ipc.h:5:
>    In file included from include/linux/spinlock.h:56:
>    In file included from include/linux/preempt.h:12:
> >> include/linux/list.h:53:13: warning: '__preserve_most__' calling convention is not supported for this target [-Wignored-attributes]
>    extern bool __list_valid_slowpath __list_add_valid_or_report(struct list_head *new,
>                ^
>    include/linux/list.h:44:39: note: expanded from macro '__list_valid_slowpath'
>    # define __list_valid_slowpath __cold __preserve_most
>                                          ^
>    include/linux/compiler_types.h:132:49: note: expanded from macro '__preserve_most'
>    # define __preserve_most notrace __attribute__((__preserve_most__))

To silence this warning, we can just guard it based on known-supported architectures:

diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index c88488715a39..c523c6683789 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -128,7 +128,7 @@ static inline void __chk_io_ptr(const volatile void __iomem *ptr) { }
  *
  * clang: https://clang.llvm.org/docs/AttributeReference.html#preserve-most
  */
-#if __has_attribute(__preserve_most__)
+#if __has_attribute(__preserve_most__) && (defined(CONFIG_X86_64) || defined(CONFIG_ARM64))
 # define __preserve_most notrace __attribute__((__preserve_most__))
 #else
 # define __preserve_most