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From: Kees Cook <keescook@chromium.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>,
	Elena Reshetova <elena.reshetova@intel.com>,
	x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Potapenko <glider@google.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Jann Horn <jannh@google.com>,
	"Perla, Enrico" <enrico.perla@intel.com>,
	kernel-hardening@lists.openwall.com,
	linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v2 2/5] init_on_alloc: Unpessimize default-on builds
Date: Tue, 24 Mar 2020 13:32:28 -0700
Message-ID: <20200324203231.64324-3-keescook@chromium.org> (raw)
In-Reply-To: <20200324203231.64324-1-keescook@chromium.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.

Signed-off-by: Kees Cook <keescook@chromium.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 059658604dd6..64e911159ffa 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2665,7 +2665,8 @@ 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;
@@ -2674,7 +2675,8 @@ 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();
 }
 
-- 
2.20.1


  parent reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24 20:32 [PATCH v2 0/5] Optionally randomize kernel stack offset each syscall Kees Cook
2020-03-24 20:32 ` [PATCH v2 1/5] jump_label: Provide CONFIG-driven build state defaults Kees Cook
2020-03-24 22:06   ` Peter Zijlstra
2020-03-24 20:32 ` Kees Cook [this message]
2020-03-26 15:48   ` [PATCH v2 2/5] init_on_alloc: Unpessimize default-on builds Alexander Potapenko
2020-03-24 20:32 ` [PATCH v2 3/5] stack: Optionally randomize kernel stack offset each syscall Kees Cook
2020-03-30 11:25   ` Mark Rutland
2020-03-30 18:18     ` Kees Cook
2020-03-30 18:27     ` Kees Cook
2020-03-24 20:32 ` [PATCH v2 4/5] x86/entry: Enable random_kstack_offset support Kees Cook
2020-03-28 22:26   ` Kees Cook
2020-03-24 20:32 ` [PATCH v2 5/5] arm64: entry: " Kees Cook
2020-03-25 13:21   ` Mark Rutland
2020-03-25 20:22     ` Kees Cook
2020-03-26 11:15       ` Mark Rutland
2020-03-26 16:31         ` Kees Cook
2020-03-30 11:26           ` Mark Rutland
2020-04-20 20:54   ` Will Deacon
2020-04-20 22:34     ` Kees Cook
2020-04-21  7:02       ` Will Deacon
2020-03-24 21:28 ` [PATCH v2 0/5] Optionally randomize kernel stack offset each syscall Jann Horn
2020-03-24 23:07   ` Kees Cook
2020-03-25 12:15     ` Reshetova, Elena
2020-03-25 20:27       ` Kees Cook
2020-03-25 23:20         ` Jann Horn
2020-03-26 17:18           ` Kees Cook

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