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>,
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 2/7] jump_label: Provide CONFIG-driven build state defaults
Date: Tue, 9 Mar 2021 13:42:56 -0800 [thread overview]
Message-ID: <20210309214301.678739-3-keescook@chromium.org> (raw)
In-Reply-To: <20210309214301.678739-1-keescook@chromium.org>
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@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 +++++++++++++++++++
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 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
*/
diff --git a/include/linux/mm.h b/include/linux/mm.h
index b3317d91ee8e..bf341a9bfe46 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2871,11 +2871,7 @@ 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
+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))
@@ -2883,11 +2879,7 @@ 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 f2d474a844cf..267c04b8911d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -167,18 +167,10 @@ 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 bool _init_on_alloc_enabled_early __read_mostly
--
2.25.1
next prev parent reply other threads:[~2021-03-09 21:43 UTC|newest]
Thread overview: 12+ 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 ` [PATCH v5 1/7] mm: Restore init_on_* static branch defaults Kees Cook
2021-03-10 23:56 ` Andrew Morton
2021-03-15 17:28 ` 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 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 ` [PATCH v5 5/7] x86/entry: Enable random_kstack_offset support Kees Cook
2021-03-09 21:43 ` [PATCH v5 6/7] arm64: entry: " Kees Cook
2021-03-09 21:43 ` [PATCH v5 7/7] lkdtm: Add REPORT_STACK for checking stack offsets Kees Cook
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