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Date: Tue, 9 Mar 2021 13:42:55 -0800
From: Kees Cook <keescook@...omium.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Kees Cook <keescook@...omium.org>,
stable@...r.kernel.org,
Elena Reshetova <elena.reshetova@...el.com>,
x86@...nel.org,
Andy Lutomirski <luto@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Potapenko <glider@...gle.com>,
Alexander Popov <alex.popov@...ux.com>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Jann Horn <jannh@...gle.com>,
kernel-hardening@...ts.openwall.com,
linux-hardening@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
Vlastimil Babka <vbabka@...e.cz>,
David Hildenbrand <david@...hat.com>,
Mike Rapoport <rppt@...ux.ibm.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Jonathan Corbet <corbet@....net>,
Randy Dunlap <rdunlap@...radead.org>
Subject: [PATCH v5 1/7] mm: Restore init_on_* static branch defaults
Choosing the initial state of static branches changes the assembly layout
(if the condition is expected to be likely, inline, or unlikely, out of
line via a jump). The _TRUE/_FALSE defines for CONFIG_INIT_ON_*_DEFAULT_ON
were accidentally removed. These need to stay so that the CONFIG controls
the pessimization of the resulting static branch NOP/JMP locations.
Fixes: 04013513cc84 ("mm, page_alloc: do not rely on the order of page_poison and init_on_alloc/free parameters")
Cc: stable@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
include/linux/mm.h | 8 ++++++++
mm/page_alloc.c | 8 ++++++++
2 files changed, 16 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 77e64e3eac80..b3317d91ee8e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2871,7 +2871,11 @@ static inline void kernel_poison_pages(struct page *page, int numpages) { }
static inline void kernel_unpoison_pages(struct page *page, int numpages) { }
#endif
+#ifdef CONFIG_INIT_ON_ALLOC_DEFAULT_ON
+DECLARE_STATIC_KEY_TRUE(init_on_alloc);
+#else
DECLARE_STATIC_KEY_FALSE(init_on_alloc);
+#endif
static inline bool want_init_on_alloc(gfp_t flags)
{
if (static_branch_unlikely(&init_on_alloc))
@@ -2879,7 +2883,11 @@ static inline bool want_init_on_alloc(gfp_t flags)
return flags & __GFP_ZERO;
}
+#ifdef CONFIG_INIT_ON_FREE_DEFAULT_ON
+DECLARE_STATIC_KEY_TRUE(init_on_free);
+#else
DECLARE_STATIC_KEY_FALSE(init_on_free);
+#endif
static inline bool want_init_on_free(void)
{
return static_branch_unlikely(&init_on_free);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3e4b29ee2b1e..f2d474a844cf 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -167,10 +167,18 @@ unsigned long totalcma_pages __read_mostly;
int percpu_pagelist_fraction;
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
+#ifdef CONFIG_INIT_ON_ALLOC_DEFAULT_ON
+DEFINE_STATIC_KEY_TRUE(init_on_alloc);
+#else
DEFINE_STATIC_KEY_FALSE(init_on_alloc);
+#endif
EXPORT_SYMBOL(init_on_alloc);
+#ifdef CONFIG_INIT_ON_FREE_DEFAULT_ON
+DEFINE_STATIC_KEY_TRUE(init_on_free);
+#else
DEFINE_STATIC_KEY_FALSE(init_on_free);
+#endif
EXPORT_SYMBOL(init_on_free);
static bool _init_on_alloc_enabled_early __read_mostly
--
2.25.1
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