[PATCHv4,02/12] atomics/x86: reduce arch_cmpxchg64*() instrumentation

Message ID 20180716113017.3909-3-mark.rutland@arm.com
State Accepted
Commit 00d5551cc4eec0fc39c3871c25c613553acfb866
Headers show
Series
  • atomics: generate atomic headers / instrument arm64
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Commit Message

Mark Rutland July 16, 2018, 11:30 a.m.
Currently x86's arch_cmpxchg64() and arch_cmpxchg64_local() are
instrumented twice, as they call into instrumented atomics rather than
their arch_ equivalents.

A call to cmpxchg64() results in:

  cmpxchg64()
    kasan_check_write()
    arch_cmpxchg64()
      cmpxchg()
        kasan_check_write()
        arch_cmpxchg()

Let's fix this up and call the arch_ equivalents, resulting in:

  cmpxchg64()
    kasan_check_write()
    arch_cmpxchg64()
      arch_cmpxchg()

Signed-off-by: Mark Rutland <mark.rutland@arm.com>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Acked-by: Will Deacon <will.deacon@arm.com>

Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/include/asm/cmpxchg_64.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

-- 
2.11.0

Comments

Thomas Gleixner July 16, 2018, 7:23 p.m. | #1
On Mon, 16 Jul 2018, Mark Rutland wrote:
> Currently x86's arch_cmpxchg64() and arch_cmpxchg64_local() are

> instrumented twice, as they call into instrumented atomics rather than

> their arch_ equivalents.

> 

> A call to cmpxchg64() results in:

> 

>   cmpxchg64()

>     kasan_check_write()

>     arch_cmpxchg64()

>       cmpxchg()

>         kasan_check_write()

>         arch_cmpxchg()

> 

> Let's fix this up and call the arch_ equivalents, resulting in:

> 

>   cmpxchg64()

>     kasan_check_write()

>     arch_cmpxchg64()

>       arch_cmpxchg()

> 

> Signed-off-by: Mark Rutland <mark.rutland@arm.com>

> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

> Acked-by: Will Deacon <will.deacon@arm.com>


Acked-by: Thomas Gleixner <tglx@linutronix.de>

Patch

diff --git a/arch/x86/include/asm/cmpxchg_64.h b/arch/x86/include/asm/cmpxchg_64.h
index bfca3b346c74..072e5459fe2f 100644
--- a/arch/x86/include/asm/cmpxchg_64.h
+++ b/arch/x86/include/asm/cmpxchg_64.h
@@ -10,13 +10,13 @@  static inline void set_64bit(volatile u64 *ptr, u64 val)
 #define arch_cmpxchg64(ptr, o, n)					\
 ({									\
 	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
-	cmpxchg((ptr), (o), (n));					\
+	arch_cmpxchg((ptr), (o), (n));					\
 })
 
 #define arch_cmpxchg64_local(ptr, o, n)					\
 ({									\
 	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
-	cmpxchg_local((ptr), (o), (n));					\
+	arch_cmpxchg_local((ptr), (o), (n));				\
 })
 
 #define system_has_cmpxchg_double() boot_cpu_has(X86_FEATURE_CX16)