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Date: Mon, 25 Jun 2018 11:59:44 +0100
From: Mark Rutland <mark.rutland@....com>
To: linux-kernel@...r.kernel.org, will.deacon@....com,
peterz@...radead.org, boqun.feng@...il.com
Cc: Mark Rutland <mark.rutland@....com>,
Dmitry Vyukov <dvyukov@...gle.com>
Subject: [PATCHv2 03/11] atomics: simplify cmpxchg() instrumentation
Currently we define some fairly verbose wrappers for the cmpxchg()
family so that we can pass a pointer and size into kasan_check_write().
The wrapper duplicate the size-switching logic necessary in arch code,
and only work for scalar types. On some architectures, (cmp)xchg are
used on non-scalar types, and thus the instrumented wrappers need to be
able to handle this.
We could take the type-punning logic form {READ,WRITE}_ONCE(), but this
makes the wrappers even more verbose, and requires several local
variables in the macros.
Instead, let's simplify the wrappers into simple macros which:
* snapshot the pointer into a single local variable, called __ai_ptr to
avoid conflicts with variables in the scope of the caller.
* call kasan_check_read() on __ai_ptr.
* invoke the arch_ function, passing the original arguments, bar
__ai_ptr being substituted for ptr.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@....com>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Will Deacon <will.deacon@....com>
---
include/asm-generic/atomic-instrumented.h | 100 +++++-------------------------
1 file changed, 15 insertions(+), 85 deletions(-)
diff --git a/include/asm-generic/atomic-instrumented.h b/include/asm-generic/atomic-instrumented.h
index 3c64e95d5ed0..c7c3e4cdd942 100644
--- a/include/asm-generic/atomic-instrumented.h
+++ b/include/asm-generic/atomic-instrumented.h
@@ -408,109 +408,39 @@ static __always_inline bool atomic64_add_negative(s64 i, atomic64_t *v)
}
#endif
-static __always_inline unsigned long
-cmpxchg_size(volatile void *ptr, unsigned long old, unsigned long new, int size)
-{
- kasan_check_write(ptr, size);
- switch (size) {
- case 1:
- return arch_cmpxchg((u8 *)ptr, (u8)old, (u8)new);
- case 2:
- return arch_cmpxchg((u16 *)ptr, (u16)old, (u16)new);
- case 4:
- return arch_cmpxchg((u32 *)ptr, (u32)old, (u32)new);
- case 8:
- BUILD_BUG_ON(sizeof(unsigned long) != 8);
- return arch_cmpxchg((u64 *)ptr, (u64)old, (u64)new);
- }
- BUILD_BUG();
- return 0;
-}
-
#define cmpxchg(ptr, old, new) \
({ \
- ((__typeof__(*(ptr)))cmpxchg_size((ptr), (unsigned long)(old), \
- (unsigned long)(new), sizeof(*(ptr)))); \
+ typeof(ptr) __ai_ptr = (ptr); \
+ kasan_check_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg(__ai_ptr, (old), (new)); \
})
-static __always_inline unsigned long
-sync_cmpxchg_size(volatile void *ptr, unsigned long old, unsigned long new,
- int size)
-{
- kasan_check_write(ptr, size);
- switch (size) {
- case 1:
- return arch_sync_cmpxchg((u8 *)ptr, (u8)old, (u8)new);
- case 2:
- return arch_sync_cmpxchg((u16 *)ptr, (u16)old, (u16)new);
- case 4:
- return arch_sync_cmpxchg((u32 *)ptr, (u32)old, (u32)new);
- case 8:
- BUILD_BUG_ON(sizeof(unsigned long) != 8);
- return arch_sync_cmpxchg((u64 *)ptr, (u64)old, (u64)new);
- }
- BUILD_BUG();
- return 0;
-}
-
#define sync_cmpxchg(ptr, old, new) \
({ \
- ((__typeof__(*(ptr)))sync_cmpxchg_size((ptr), \
- (unsigned long)(old), (unsigned long)(new), \
- sizeof(*(ptr)))); \
+ typeof(ptr) __ai_ptr = (ptr); \
+ kasan_check_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_sync_cmpxchg(__ai_ptr, (old), (new)); \
})
-static __always_inline unsigned long
-cmpxchg_local_size(volatile void *ptr, unsigned long old, unsigned long new,
- int size)
-{
- kasan_check_write(ptr, size);
- switch (size) {
- case 1:
- return arch_cmpxchg_local((u8 *)ptr, (u8)old, (u8)new);
- case 2:
- return arch_cmpxchg_local((u16 *)ptr, (u16)old, (u16)new);
- case 4:
- return arch_cmpxchg_local((u32 *)ptr, (u32)old, (u32)new);
- case 8:
- BUILD_BUG_ON(sizeof(unsigned long) != 8);
- return arch_cmpxchg_local((u64 *)ptr, (u64)old, (u64)new);
- }
- BUILD_BUG();
- return 0;
-}
-
#define cmpxchg_local(ptr, old, new) \
({ \
- ((__typeof__(*(ptr)))cmpxchg_local_size((ptr), \
- (unsigned long)(old), (unsigned long)(new), \
- sizeof(*(ptr)))); \
+ typeof(ptr) __ai_ptr = (ptr); \
+ kasan_check_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg_local(__ai_ptr, (old), (new)); \
})
-static __always_inline u64
-cmpxchg64_size(volatile u64 *ptr, u64 old, u64 new)
-{
- kasan_check_write(ptr, sizeof(*ptr));
- return arch_cmpxchg64(ptr, old, new);
-}
-
#define cmpxchg64(ptr, old, new) \
({ \
- ((__typeof__(*(ptr)))cmpxchg64_size((ptr), (u64)(old), \
- (u64)(new))); \
+ typeof(ptr) __ai_ptr = (ptr); \
+ kasan_check_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg64(__ai_ptr, (old), (new)); \
})
-static __always_inline u64
-cmpxchg64_local_size(volatile u64 *ptr, u64 old, u64 new)
-{
- kasan_check_write(ptr, sizeof(*ptr));
- return arch_cmpxchg64_local(ptr, old, new);
-}
-
#define cmpxchg64_local(ptr, old, new) \
({ \
- ((__typeof__(*(ptr)))cmpxchg64_local_size((ptr), (u64)(old), \
- (u64)(new))); \
+ typeof(ptr) __ai_ptr = (ptr); \
+ kasan_check_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg64_local(__ai_ptr, (old), (new)); \
})
/*
--
2.11.0
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