From: Kees Cook <keescook@chromium.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>,
Alexander Potapenko <glider@google.com>,
Vlastimil Babka <vbabka@suse.cz>,
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>,
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>,
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
Subject: [PATCH v7 2/6] init_on_alloc: Optimize static branches
Date: Fri, 19 Mar 2021 14:28:31 -0700 [thread overview]
Message-ID: <20210319212835.3928492-3-keescook@chromium.org> (raw)
In-Reply-To: <20210319212835.3928492-1-keescook@chromium.org>
The state of CONFIG_INIT_ON_ALLOC_DEFAULT_ON (and ...ON_FREE...) did not
change the assembly ordering of the static branches: they were always out
of line. Use the new jump_label macros to check the CONFIG settings to
default to the "expected" state, which slightly optimizes the resulting
assembly code.
Reviewed-by: Alexander Potapenko <glider@google.com>
Link: https://lore.kernel.org/lkml/CAG_fn=X0DVwqLaHJTO6Jw7TGcMSm77GKHinrd0m_6y0SzWOrFA@mail.gmail.com/
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Link: https://lore.kernel.org/lkml/5d626b9b-5355-be94-e8e2-1be47f880f30@suse.cz
Signed-off-by: Kees Cook <keescook@chromium.org>
---
include/linux/mm.h | 10 ++++++----
mm/page_alloc.c | 4 ++--
mm/slab.h | 6 ++++--
3 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 77e64e3eac80..2ccd856ac0d1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2871,18 +2871,20 @@ static inline void kernel_poison_pages(struct page *page, int numpages) { }
static inline void kernel_unpoison_pages(struct page *page, int numpages) { }
#endif
-DECLARE_STATIC_KEY_FALSE(init_on_alloc);
+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;
}
-DECLARE_STATIC_KEY_FALSE(init_on_free);
+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;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3e4b29ee2b1e..267c04b8911d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -167,10 +167,10 @@ unsigned long totalcma_pages __read_mostly;
int percpu_pagelist_fraction;
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
-DEFINE_STATIC_KEY_FALSE(init_on_alloc);
+DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, init_on_alloc);
EXPORT_SYMBOL(init_on_alloc);
-DEFINE_STATIC_KEY_FALSE(init_on_free);
+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
diff --git a/mm/slab.h b/mm/slab.h
index 076582f58f68..774c7221efdc 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -601,7 +601,8 @@ static inline void cache_random_seq_destroy(struct kmem_cache *cachep) { }
static inline bool slab_want_init_on_alloc(gfp_t flags, struct kmem_cache *c)
{
- if (static_branch_unlikely(&init_on_alloc)) {
+ if (static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON,
+ &init_on_alloc)) {
if (c->ctor)
return false;
if (c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON))
@@ -613,7 +614,8 @@ static inline bool slab_want_init_on_alloc(gfp_t flags, struct kmem_cache *c)
static inline bool slab_want_init_on_free(struct kmem_cache *c)
{
- if (static_branch_unlikely(&init_on_free))
+ if (static_branch_maybe(CONFIG_INIT_ON_FREE_DEFAULT_ON,
+ &init_on_free))
return !(c->ctor ||
(c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)));
return false;
--
2.25.1
next prev parent reply other threads:[~2021-03-19 21:29 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-19 21:28 [PATCH v7 0/6] Optionally randomize kernel stack offset each syscall Kees Cook
2021-03-19 21:28 ` [PATCH v7 1/6] jump_label: Provide CONFIG-driven build state defaults Kees Cook
2021-03-19 21:28 ` Kees Cook [this message]
2021-03-19 21:28 ` [PATCH v7 3/6] stack: Optionally randomize kernel stack offset each syscall Kees Cook
2021-03-28 14:42 ` Thomas Gleixner
2021-03-29 18:41 ` Kees Cook
2021-03-19 21:28 ` [PATCH v7 4/6] x86/entry: Enable random_kstack_offset support Kees Cook
2021-03-20 11:58 ` Ingo Molnar
2021-03-21 17:03 ` Kees Cook
2021-03-28 14:18 ` Thomas Gleixner
2021-03-29 18:43 ` Kees Cook
2021-03-19 21:28 ` [PATCH v7 5/6] arm64: entry: " Kees Cook
2021-04-01 8:34 ` Will Deacon
2021-03-19 21:28 ` [PATCH v7 6/6] lkdtm: Add REPORT_STACK for checking stack offsets Kees Cook
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