From: Kees Cook <keescook@chromium.org> To: Thomas Gleixner <tglx@linutronix.de> Cc: Kees Cook <keescook@chromium.org>, Peter Zijlstra <peterz@infradead.org>, Elena Reshetova <elena.reshetova@intel.com>, x86@kernel.org, Andy Lutomirski <luto@kernel.org>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Alexander Potapenko <glider@google.com>, Alexander Popov <alex.popov@linux.com>, Ard Biesheuvel <ard.biesheuvel@linaro.org>, Jann Horn <jannh@google.com>, Vlastimil Babka <vbabka@suse.cz>, David Hildenbrand <david@redhat.com>, Mike Rapoport <rppt@linux.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, Jonathan Corbet <corbet@lwn.net>, Randy Dunlap <rdunlap@infradead.org>, 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 v6 1/6] jump_label: Provide CONFIG-driven build state defaults Date: Mon, 15 Mar 2021 11:02:24 -0700 [thread overview] Message-ID: <20210315180229.1224655-2-keescook@chromium.org> (raw) In-Reply-To: <20210315180229.1224655-1-keescook@chromium.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) <peterz@infradead.org> Link: https://lore.kernel.org/lkml/20200324220641.GT2452@worktop.programming.kicks-ass.net/ Signed-off-by: Kees Cook <keescook@chromium.org> --- 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
WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org> To: Thomas Gleixner <tglx@linutronix.de> Cc: Kees Cook <keescook@chromium.org>, Peter Zijlstra <peterz@infradead.org>, Elena Reshetova <elena.reshetova@intel.com>, x86@kernel.org, Andy Lutomirski <luto@kernel.org>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Alexander Potapenko <glider@google.com>, Alexander Popov <alex.popov@linux.com>, Ard Biesheuvel <ard.biesheuvel@linaro.org>, Jann Horn <jannh@google.com>, Vlastimil Babka <vbabka@suse.cz>, David Hildenbrand <david@redhat.com>, Mike Rapoport <rppt@linux.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, Jonathan Corbet <corbet@lwn.net>, Randy Dunlap <rdunlap@infradead.org>, 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 v6 1/6] jump_label: Provide CONFIG-driven build state defaults Date: Mon, 15 Mar 2021 11:02:24 -0700 [thread overview] Message-ID: <20210315180229.1224655-2-keescook@chromium.org> (raw) In-Reply-To: <20210315180229.1224655-1-keescook@chromium.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) <peterz@infradead.org> Link: https://lore.kernel.org/lkml/20200324220641.GT2452@worktop.programming.kicks-ass.net/ Signed-off-by: Kees Cook <keescook@chromium.org> --- 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-03-15 18:03 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-03-15 18:02 [PATCH v6 0/6] Optionally randomize kernel stack offset each syscall Kees Cook 2021-03-15 18:02 ` Kees Cook 2021-03-15 18:02 ` Kees Cook [this message] 2021-03-15 18:02 ` [PATCH v6 1/6] jump_label: Provide CONFIG-driven build state defaults Kees Cook 2021-03-15 18:02 ` [PATCH v6 2/6] init_on_alloc: Optimize static branches Kees Cook 2021-03-15 18:02 ` Kees Cook 2021-03-15 22:15 ` Kees Cook 2021-03-15 22:15 ` Kees Cook 2021-03-18 12:46 ` Vlastimil Babka 2021-03-18 12:46 ` Vlastimil Babka 2021-03-15 18:02 ` [PATCH v6 3/6] stack: Optionally randomize kernel stack offset each syscall Kees Cook 2021-03-15 18:02 ` Kees Cook 2021-03-15 18:02 ` [PATCH v6 4/6] x86/entry: Enable random_kstack_offset support Kees Cook 2021-03-15 18:02 ` Kees Cook 2021-03-15 18:02 ` [PATCH v6 5/6] arm64: entry: " Kees Cook 2021-03-15 18:02 ` Kees Cook 2021-03-15 18:02 ` [PATCH v6 6/6] lkdtm: Add REPORT_STACK for checking stack offsets Kees Cook 2021-03-15 18:02 ` Kees Cook
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