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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id h14sm6057417pjc.37.2021.03.19.14.28.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Mar 2021 14:28:38 -0700 (PDT) From: Kees Cook To: Thomas Gleixner Cc: Kees Cook , Peter Zijlstra , Elena Reshetova , x86@kernel.org, Andy Lutomirski , Catalin Marinas , Will Deacon , Mark Rutland , Alexander Potapenko , Alexander Popov , Ard Biesheuvel , Jann Horn , Vlastimil Babka , David Hildenbrand , Mike Rapoport , Andrew Morton , Jonathan Corbet , Randy Dunlap , kernel-hardening@lists.openwall.com, linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v7 1/6] jump_label: Provide CONFIG-driven build state defaults Date: Fri, 19 Mar 2021 14:28:30 -0700 Message-Id: <20210319212835.3928492-2-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210319212835.3928492-1-keescook@chromium.org> References: <20210319212835.3928492-1-keescook@chromium.org> MIME-Version: 1.0 X-Patch-Hashes: v=1; h=sha256; g=aa54c44d1d71b9550d6015efc734f667917094a1; i=Vishx6UyAXwYzcnoSyP+eBB3iQyx+/i5smsbQfc0cnA=; m=vc4sSYlf+uaSlLSFP5TpbQv56VaSRpBLpRuMltXaB4Q=; p=mNH2Bo/K9vrGz9sBtTDV8UFO0eJ8yv8BbR/DeIaO1es= X-Patch-Sig: m=pgp; i=keescook@chromium.org; s=0x0x8972F4DFDC6DC026; b=iQIzBAABCgAdFiEEpcP2jyKd1g9yPm4TiXL039xtwCYFAmBVF4EACgkQiXL039xtwCYoKQ//WsO JhBKVKfDUIyIOwrMCU3Z/kRQjSwDXUlgTtwiYp36T0IJ3d76UirWkyQFSy0y5HMNMyGbGhto2ftzU 7iBhSN/U2EHLY80ksg28k/Xw8jFC36JeiIgqYDWJHbE6d5D5MDzR6+ubtytgB1aNhCuOpETM6HMkZ t5Ckc7Bk31LbOuKiVpG6nzLce4/BxOYq9vzWNPU8g7YB17QXuTDWgurYMwMXytg5uUR6vdCgOKeaH fNyC+StIV1Lj9LzoYgRQKXXYFXduWjWKZ3WcYpJfwgStKSe9uhM6MvfA3aW9W6f5+n/SQS7Yejt5E YYTBCKbMqEIHMuruza2MOMKuyIoK9bT1qvbzDJCEoCXh/DuiSUbdxpMMgtcwPdkxiHHkUPzhkIl7H DwQY5X+eVbPVxL8W9QoKeq+8d/Ve4ASwv4kzDFC65vq5+WI6sK0pQsT4u/3Rcu8sEf0GC25e4tELr 7R0tPXMOgYkGsKM9dVtfSLbQJjvHmaRWJmZrufU9nmYGQuavWsaVkQJTKMY2SkUevJNw+KxlrUCmz gsgT24T5dWCOZao0jTacVwTJ/WKm7vV7SnxTvandK270LFmG5gK/1USGGs8znRoMJPkDE4Ktfzruf pZUWQhHZoMIENQGhElqSlhCvcRS0QOcc9VmehZJGxju+EVvlYvvLM5JDtvaCjRnw= Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As shown in jump_label.h[1], choosing the initial state of static branches changes the assembly layout. If the condition is expected to be likely it's inline, and if unlikely it is out of line via a jump. A few places in the kernel use (or could be using) a CONFIG to choose the default state, which would give a small performance benefit to their compile-time declared default. Provide the infrastructure to do this. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/jump_label.h?h=v5.11#n398 Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/lkml/20200324220641.GT2452@worktop.programming.kicks-ass.net/ Signed-off-by: Kees Cook --- include/linux/jump_label.h | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index d92691262f51..05f5554d860f 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -382,6 +382,21 @@ struct static_key_false { [0 ... (count) - 1] = STATIC_KEY_FALSE_INIT, \ } +#define _DEFINE_STATIC_KEY_1(name) DEFINE_STATIC_KEY_TRUE(name) +#define _DEFINE_STATIC_KEY_0(name) DEFINE_STATIC_KEY_FALSE(name) +#define DEFINE_STATIC_KEY_MAYBE(cfg, name) \ + __PASTE(_DEFINE_STATIC_KEY_, IS_ENABLED(cfg))(name) + +#define _DEFINE_STATIC_KEY_RO_1(name) DEFINE_STATIC_KEY_TRUE_RO(name) +#define _DEFINE_STATIC_KEY_RO_0(name) DEFINE_STATIC_KEY_FALSE_RO(name) +#define DEFINE_STATIC_KEY_MAYBE_RO(cfg, name) \ + __PASTE(_DEFINE_STATIC_KEY_RO_, IS_ENABLED(cfg))(name) + +#define _DECLARE_STATIC_KEY_1(name) DECLARE_STATIC_KEY_TRUE(name) +#define _DECLARE_STATIC_KEY_0(name) DECLARE_STATIC_KEY_FALSE(name) +#define DECLARE_STATIC_KEY_MAYBE(cfg, name) \ + __PASTE(_DECLARE_STATIC_KEY_, IS_ENABLED(cfg))(name) + extern bool ____wrong_branch_error(void); #define static_key_enabled(x) \ @@ -482,6 +497,10 @@ extern bool ____wrong_branch_error(void); #endif /* CONFIG_JUMP_LABEL */ +#define static_branch_maybe(config, x) \ + (IS_ENABLED(config) ? static_branch_likely(x) \ + : static_branch_unlikely(x)) + /* * Advanced usage; refcount, branch is enabled when: count != 0 */ -- 2.25.1