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Message-Id: <20200622193146.2985288-3-keescook@chromium.org> Date: Mon, 22 Jun 2020 12:31:43 -0700 From: Kees Cook <keescook@...omium.org> To: Thomas Gleixner <tglx@...utronix.de> Cc: Kees Cook <keescook@...omium.org>, Alexander Potapenko <glider@...gle.com>, Elena Reshetova <elena.reshetova@...el.com>, x86@...nel.org, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>, Alexander Popov <alex.popov@...ux.com>, Ard Biesheuvel <ard.biesheuvel@...aro.org>, Jann Horn <jannh@...gle.com>, kernel-hardening@...ts.openwall.com, linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org Subject: [PATCH v4 2/5] init_on_alloc: Unpessimize default-on builds 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@...gle.com> Signed-off-by: Kees Cook <keescook@...omium.org> --- 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 0e6824fd4458..0a05b20870c2 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2892,7 +2892,8 @@ static inline void kernel_poison_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) && !page_poisoning_enabled()) return true; return flags & __GFP_ZERO; @@ -2901,7 +2902,8 @@ 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) && !page_poisoning_enabled(); } -- 2.25.1
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