From aa9695157f65c55e5c85a1c194859d3c03e68018 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 13 Dec 2022 17:13:10 +0100 Subject: crypto: scatterwalk - use kmap_local() not kmap_atomic() kmap_atomic() is used to create short-lived mappings of pages that may not be accessible via the kernel direct map. This is only needed on 32-bit architectures that implement CONFIG_HIGHMEM, but it can be used on 64-bit other architectures too, where the returned mapping is simply the kernel direct address of the page. However, kmap_atomic() does not support migration on CONFIG_HIGHMEM configurations, due to the use of per-CPU kmap slots, and so it disables preemption on all architectures, not just the 32-bit ones. This implies that all scatterwalk based crypto routines essentially execute with preemption disabled all the time, which is less than ideal. So let's switch scatterwalk_map/_unmap and the shash/ahash routines to kmap_local() instead, which serves a similar purpose, but without the resulting impact on preemption on architectures that have no need for CONFIG_HIGHMEM. Cc: Eric Biggers Cc: Herbert Xu Cc: "Elliott, Robert (Servers)" Signed-off-by: Ard Biesheuvel Signed-off-by: Herbert Xu --- include/crypto/scatterwalk.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/crypto') diff --git a/include/crypto/scatterwalk.h b/include/crypto/scatterwalk.h index f2c42b4111b1..32fc4473175b 100644 --- a/include/crypto/scatterwalk.h +++ b/include/crypto/scatterwalk.h @@ -53,7 +53,7 @@ static inline struct page *scatterwalk_page(struct scatter_walk *walk) static inline void scatterwalk_unmap(void *vaddr) { - kunmap_atomic(vaddr); + kunmap_local(vaddr); } static inline void scatterwalk_start(struct scatter_walk *walk, @@ -65,7 +65,7 @@ static inline void scatterwalk_start(struct scatter_walk *walk, static inline void *scatterwalk_map(struct scatter_walk *walk) { - return kmap_atomic(scatterwalk_page(walk)) + + return kmap_local_page(scatterwalk_page(walk)) + offset_in_page(walk->offset); } -- cgit v1.2.3