On Fri, Feb 16, 2024 at 12:16 AM Petr Pavlu <petr.pavlu@xxxxxxxx> wrote: > > GCC recently added option -fmin-function-alignment, which should appear > in GCC 14. Unlike -falign-functions, this option causes all functions to > be aligned at the specified value, including the cold ones. > > Detect availability of -fmin-function-alignment and use it instead of > -falign-functions when present. Introduce CC_HAS_SANE_FUNCTION_ALIGNMENT > and make the workarounds for the broken function alignment conditional > on this setting. > > Signed-off-by: Petr Pavlu <petr.pavlu@xxxxxxxx> > --- [snip] > index dfb963d2f862..5a6fed4ad3df 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -1920,7 +1920,10 @@ EXPORT_SYMBOL(thread_group_exited); > * > * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88345#c11 > */ > -__weak __function_aligned void abort(void) > +#ifndef CONFIG_CC_HAS_SANE_FUNCTION_ALIGNMENT > +__function_aligned > +#endif > +__weak void abort(void) > { > BUG(); __function_aligned is conditionally defined in include/linux/compiler_types.h, and then it is conditionally used in kernel/exit.c This is unreadable. You may want to move CONFIG_CC_HAS_SANE_FUNCTION_ALIGNMENT to include/linux/compiler_types.h, as this is more aligned with what you did for __cold. if !defined(CONFIG_CC_HAS_SANE_FUNCTION_ALIGNMENT) && \ CONFIG_FUNCTION_ALIGNMENT > 0 #define __function_aligned __aligned(CONFIG_FUNCTION_ALIGNMENT) #else #define __function_aligned #endif However, an even more elegant approach is to unify the two #ifdef blocks because __cold and __function_aligned are related to each other. #if defined(CONFIG_CC_HAS_SANE_FUNCTION_ALIGNMENT) || \ (CONFIG_FUNCTION_ALIGNMENT == 0) #define __cold __attribute__((__cold__)) #define __function_aligned #else #define __cold #define __function_aligned __aligned(CONFIG_FUNCTION_ALIGNMENT) #endif -- Best Regards Masahiro Yamada
