Le 24/01/2023 à 22:54, Benjamin Gray a écrit : > Converts the BUILD_BUG to a WARN to allow building with a low/unoptimised > compiler.
No no no no. Please don't do that. That approach is used everywhere in the kernel, why should it be a problem only for local_flush_tlb_page_psize() and not everywhere else ? Really if it doesn't work it means there is a deep problem in your compiler. We really don't want the overhead of WARN over BUILD_BUG in the normal case. By the way, are you should the problem is really BUILD_BUG() ? Looking at your patch I would think that the problem is because it is "static inline". Have you tried 'static __always_inline' instead ? Christophe > > The original expectation was that a compiler would see that the only > usage of this function was in a function that is only called behind > radix-only guards. And it worked this way on GCC. It seems Clang does > not optimise away this call however, so thinks the function may be > invoked and triggers the build bug as reported by the kernel test robot. > > https://lore.kernel.org/llvm/202301212348.edkowvff-...@intel.com > > This fix converts the build bug to a warning to allow builds without > relying on particular compiler optimisation behaviours. The warning is > not rate limited because this implementation should still never be called > as-is, and anyone who might invoke it might appreciate it being very > obvious that it's not behaving as expected. > > Fixes: 274d842fa1ef ("powerpc/tlb: Add local flush for page given mm_struct > and psize") > Reported-by: kernel test robot <l...@intel.com> > Signed-off-by: Benjamin Gray <bg...@linux.ibm.com> > --- > arch/powerpc/include/asm/book3s/32/tlbflush.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/include/asm/book3s/32/tlbflush.h > b/arch/powerpc/include/asm/book3s/32/tlbflush.h > index 4be572908124..675196884640 100644 > --- a/arch/powerpc/include/asm/book3s/32/tlbflush.h > +++ b/arch/powerpc/include/asm/book3s/32/tlbflush.h > @@ -2,7 +2,7 @@ > #ifndef _ASM_POWERPC_BOOK3S_32_TLBFLUSH_H > #define _ASM_POWERPC_BOOK3S_32_TLBFLUSH_H > > -#include <linux/build_bug.h> > +#include <linux/bug.h> > > #define MMU_NO_CONTEXT (0) > /* > @@ -80,7 +80,7 @@ static inline void local_flush_tlb_page(struct > vm_area_struct *vma, > static inline void local_flush_tlb_page_psize(struct mm_struct *mm, > unsigned long vmaddr, int psize) > { > - BUILD_BUG(); > + WARN(1, "Unimplemented local TLB flush with psize"); > } > > static inline void local_flush_tlb_mm(struct mm_struct *mm) > > base-commit: 53ab112a95086d10dc353ea4f979abb01644bbb6
