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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id y18sm14064284pfn.177.2020.06.22.12.31.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jun 2020 12:31:50 -0700 (PDT) From: Kees Cook To: Thomas Gleixner Cc: Kees Cook , Alexander Potapenko , Elena Reshetova , x86@kernel.org, Andy Lutomirski , Peter Zijlstra , Catalin Marinas , Will Deacon , Mark Rutland , Alexander Popov , Ard Biesheuvel , Jann Horn , kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 2/5] init_on_alloc: Unpessimize default-on builds Date: Mon, 22 Jun 2020 12:31:43 -0700 Message-Id: <20200622193146.2985288-3-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200622193146.2985288-1-keescook@chromium.org> References: <20200622193146.2985288-1-keescook@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Signed-off-by: Kees Cook --- 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