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From: Kees Cook <keescook@chromium.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>,
	Alexander Potapenko <glider@google.com>,
	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 Popov <alex.popov@linux.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Jann Horn <jannh@google.com>,
	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, 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>
Subject: [PATCH v5 3/7] init_on_alloc: Unpessimize default-on builds
Date: Tue,  9 Mar 2021 13:42:57 -0800	[thread overview]
Message-ID: <20210309214301.678739-4-keescook@chromium.org> (raw)
In-Reply-To: <20210309214301.678739-1-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.

Reviewed-by: Alexander Potapenko <glider@google.com>
Link: https://lore.kernel.org/lkml/CAG_fn=X0DVwqLaHJTO6Jw7TGcMSm77GKHinrd0m_6y0SzWOrFA@mail.gmail.com/
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 bf341a9bfe46..2ccd856ac0d1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2874,7 +2874,8 @@ static inline void kernel_unpoison_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))
 		return true;
 	return flags & __GFP_ZERO;
 }
@@ -2882,7 +2883,8 @@ 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);
 }
 
 extern bool _debug_pagealloc_enabled_early;
-- 
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>,
	Alexander Potapenko <glider@google.com>,
	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 Popov <alex.popov@linux.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Jann Horn <jannh@google.com>,
	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, 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>
Subject: [PATCH v5 3/7] init_on_alloc: Unpessimize default-on builds
Date: Tue,  9 Mar 2021 13:42:57 -0800	[thread overview]
Message-ID: <20210309214301.678739-4-keescook@chromium.org> (raw)
In-Reply-To: <20210309214301.678739-1-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.

Reviewed-by: Alexander Potapenko <glider@google.com>
Link: https://lore.kernel.org/lkml/CAG_fn=X0DVwqLaHJTO6Jw7TGcMSm77GKHinrd0m_6y0SzWOrFA@mail.gmail.com/
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 bf341a9bfe46..2ccd856ac0d1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2874,7 +2874,8 @@ static inline void kernel_unpoison_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))
 		return true;
 	return flags & __GFP_ZERO;
 }
@@ -2882,7 +2883,8 @@ 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);
 }
 
 extern bool _debug_pagealloc_enabled_early;
-- 
2.25.1


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linux-arm-kernel mailing list
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2021-03-09 21:44 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-09 21:42 [PATCH v5 0/7] Optionally randomize kernel stack offset each syscall Kees Cook
2021-03-09 21:42 ` Kees Cook
2021-03-09 21:42 ` [PATCH v5 1/7] mm: Restore init_on_* static branch defaults Kees Cook
2021-03-09 21:42   ` Kees Cook
2021-03-10 23:56   ` Andrew Morton
2021-03-10 23:56     ` Andrew Morton
2021-03-15 17:28     ` Kees Cook
2021-03-15 17:28       ` Kees Cook
2021-03-09 21:42 ` [PATCH v5 2/7] jump_label: Provide CONFIG-driven build state defaults Kees Cook
2021-03-09 21:42   ` Kees Cook
2021-03-09 21:42 ` Kees Cook [this message]
2021-03-09 21:42   ` [PATCH v5 3/7] init_on_alloc: Unpessimize default-on builds Kees Cook
2021-03-10 12:52   ` Andrey Konovalov
2021-03-10 12:52     ` Andrey Konovalov
2021-03-10 12:52     ` Andrey Konovalov
2021-03-10 21:03     ` Kees Cook
2021-03-10 21:03       ` Kees Cook
2021-03-09 21:42 ` [PATCH v5 4/7] stack: Optionally randomize kernel stack offset each syscall Kees Cook
2021-03-09 21:42   ` Kees Cook
2021-03-09 21:42 ` [PATCH v5 5/7] x86/entry: Enable random_kstack_offset support Kees Cook
2021-03-09 21:42   ` Kees Cook
2021-03-09 21:43 ` [PATCH v5 6/7] arm64: entry: " Kees Cook
2021-03-09 21:43   ` Kees Cook
2021-03-09 21:43 ` [PATCH v5 7/7] lkdtm: Add REPORT_STACK for checking stack offsets Kees Cook
2021-03-09 21:43   ` Kees Cook

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