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locking/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 wrappers 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 from {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_write() on __ai_ptr.

* invoke the relevant 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@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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andy.shevchenko@gmail.com
Cc: arnd@arndb.de
Cc: aryabinin@virtuozzo.com
Cc: catalin.marinas@arm.com
Cc: glider@google.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: parri.andrea@gmail.com
Cc: peter@hurleysoftware.com
Link: http://lkml.kernel.org/r/20180716113017.3909-4-mark.rutland@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Mark Rutland 2018-07-16 12:30:08 +01:00 committed by Ingo Molnar
parent 00d5551cc4
commit df79ed2c06
1 changed files with 15 additions and 85 deletions
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100
include/asm-generic/atomic-instrumented.h
View File

@ -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)); \
})
/*