[PATCH v5 3/7] init_on_alloc: Unpessimize default-on builds
From: Kees Cook <hidden>
Date: 2021-03-09 21:44:02
Also in:
linux-arm-kernel, linux-hardening, lkml
Subsystem:
memory management - core, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
Right now, the state of CONFIG_INIT_ON_ALLOC_DEFAULT_ON (and ...ON_FREE...) did not change the assembly ordering of the static branch tests. Use the new jump_label macro to check CONFIG settings to default to the "expected" state, unpessimizes the resulting assembly code. Reviewed-by: Alexander Potapenko <glider@google.com> Link: https://lore.kernel.org/lkml/CAG_fn=X0DVwqLaHJTO6Jw7TGcMSm77GKHinrd0m_6y0SzWOrFA@mail.gmail.com/ (local) Signed-off-by: Kees Cook <redacted> --- include/linux/mm.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index bf341a9bfe46..2ccd856ac0d1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -2874,7 +2874,8 @@ static inline void kernel_unpoison_pages(struct page *page, int numpages) { } DECLARE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, init_on_alloc); static inline bool want_init_on_alloc(gfp_t flags) { - if (static_branch_unlikely(&init_on_alloc)) + if (static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, + &init_on_alloc)) return true; return flags & __GFP_ZERO; }
@@ -2882,7 +2883,8 @@ static inline bool want_init_on_alloc(gfp_t flags) DECLARE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_FREE_DEFAULT_ON, init_on_free); static inline bool want_init_on_free(void) { - return static_branch_unlikely(&init_on_free); + return static_branch_maybe(CONFIG_INIT_ON_FREE_DEFAULT_ON, + &init_on_free); } extern bool _debug_pagealloc_enabled_early;
--
2.25.1