From 16d91faf09be148d9c1cf4999f4d15fb24a7cd72 Mon Sep 17 00:00:00 2001 From: Peter Collingbourne Date: Thu, 16 Feb 2023 11:59:24 -0800 Subject: kasan: call clear_page with a match-all tag instead of changing page tag Instead of changing the page's tag solely in order to obtain a pointer with a match-all tag and then changing it back again, just convert the pointer that we get from kmap_atomic() into one with a match-all tag before passing it to clear_page(). On a certain microarchitecture, this has been observed to cause a measurable improvement in microbenchmark performance, presumably as a result of being able to avoid the atomic operations on the page tag. Link: https://lkml.kernel.org/r/20230216195924.3287772-1-pcc@google.com Signed-off-by: Peter Collingbourne Link: https://linux-review.googlesource.com/id/I0249822cc29097ca7a04ad48e8eb14871f80e711 Reviewed-by: Andrey Konovalov Reviewed-by: Catalin Marinas Cc: Andrey Ryabinin Cc: Evgenii Stepanov Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton --- include/linux/highmem.h | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'include/linux/highmem.h') diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 8fc10089e19e..9c7cdaa3de8c 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -243,12 +243,10 @@ static inline void clear_highpage(struct page *page) static inline void clear_highpage_kasan_tagged(struct page *page) { - u8 tag; + void *kaddr = kmap_local_page(page); - tag = page_kasan_tag(page); - page_kasan_tag_reset(page); - clear_highpage(page); - page_kasan_tag_set(page, tag); + clear_page(kasan_reset_tag(kaddr)); + kunmap_local(kaddr); } #ifndef __HAVE_ARCH_TAG_CLEAR_HIGHPAGE -- cgit v1.2.3