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Message-Id: <20200622193146.2985288-2-keescook@chromium.org>
Date: Mon, 22 Jun 2020 12:31:42 -0700
From: Kees Cook <keescook@...omium.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Kees Cook <keescook@...omium.org>,
Peter Zijlstra <peterz@...radead.org>,
Elena Reshetova <elena.reshetova@...el.com>,
x86@...nel.org,
Andy Lutomirski <luto@...nel.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-arm-kernel@...ts.infradead.org,
linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v4 1/5] jump_label: Provide CONFIG-driven build state 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). A few places in the kernel use (or could be
using) a CONFIG to choose the default state, so provide the
infrastructure to do this and convert the existing cases (init_on_alloc
and init_on_free) to the new macros.
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
include/linux/jump_label.h | 19 +++++++++++++++++++
include/linux/mm.h | 12 ++----------
mm/page_alloc.c | 12 ++----------
3 files changed, 23 insertions(+), 20 deletions(-)
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 3526c0aee954..615fdfb871a3 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
*/
diff --git a/include/linux/mm.h b/include/linux/mm.h
index dc7b87310c10..0e6824fd4458 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2889,11 +2889,7 @@ static inline void kernel_poison_pages(struct page *page, int numpages,
int enable) { }
#endif
-#ifdef CONFIG_INIT_ON_ALLOC_DEFAULT_ON
-DECLARE_STATIC_KEY_TRUE(init_on_alloc);
-#else
-DECLARE_STATIC_KEY_FALSE(init_on_alloc);
-#endif
+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) &&
@@ -2902,11 +2898,7 @@ 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
+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) &&
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 48eb0f1410d4..5885a612fa18 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -136,18 +136,10 @@ 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
+DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, init_on_alloc);
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
+DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_FREE_DEFAULT_ON, init_on_free);
EXPORT_SYMBOL(init_on_free);
static int __init early_init_on_alloc(char *buf)
--
2.25.1
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