Messages in this thread | | | Date | Wed, 28 Jun 2017 17:24:24 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH] locking/atomics: don't alias ____ptr |
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On Wed, 28 Jun 2017, Mark Rutland wrote: > On Wed, Jun 28, 2017 at 03:54:42PM +0200, Thomas Gleixner wrote: > > > static inline unsigned long cmpxchg_varsize(void *ptr, unsigned long old, > > > unsigned long new, int size) > > > { > > > switch (size) { > > > case 1: > > > case 2: > > > case 4: > > > break; > > > case 8: > > > if (sizeof(unsigned long) == 8) > > > break; > > > default: > > > BUILD_BUG_ON(1); > > > } > > > kasan_check(ptr, size); > > > return arch_cmpxchg(ptr, old, new); > > > } > > This'll need to re-cast things before the call to arch_cmpxchg(), and we > can move the check above the switch, as in [2].
Sure, but I rather see that changed to:
1) Create arch_cmpxchg8/16/32/64() inlines first
2) Add that varsize wrapper:
static inline unsigned long cmpxchg_varsize(void *ptr, unsigned long old, unsigned long new, int size) { switch (size) { case 1: kasan_check_write(ptr, size); return arch_cmpxchg8((u8 *)ptr, (u8) old, (u8)new); case 2: kasan_check_write(ptr, size); return arch_cmpxchg16((u16 *)ptr, (u16) old, (u16)new); case 4: kasan_check_write(ptr, size); return arch_cmpxchg32((u32 *)ptr, (u32) old, (u32)new); case 8: if (sizeof(unsigned long) == 8) { kasan_check_write(ptr, size); return arch_cmpxchg64((u64 *)ptr, (u64) old, (u64)new); } default: BUILD_BUG(); } }
#define cmpxchg(ptr, o, n) \ ({ \ ((__typeof__(*(ptr)))cmpxchg_varsize((ptr), (unsigned long)(o), \ (unsigned long)(n), sizeof(*(ptr)))); \ })
Which allows us to create:
static inline u8 cmpxchg8(u8 *ptr, u8 old, u8 new) { kasan_check_write(ptr, sizeof(old)); return arch_cmpxchg8(ptr, old, new); }
and friends as well and later migrate the existing users away from that untyped macro mess.
And instead of adding
#include <asm/atomic-instrumented.h>
to the architecture code, we rather do
# mv arch/xxx/include/asm/atomic.h mv arch/xxx/include/asm/arch_atomic.h # echo '#include <asm-generic/atomic.h>' >arch/xxx/include/asm/atomic.h
# mv include/asm-generic/atomic.h include/asm-generic/atomic_up.h
and create a new include/asm-generic/atomic.h
#ifndef __ASM_GENERIC_ATOMIC_H #define __ASM_GENERIC_ATOMIC_H
#ifdef CONFIG_ATOMIC_INSTRUMENTED_H #include <asm-generic/atomic_instrumented.h> #else #include <asm-generic/atomic_up.h> #endif
#endif
Thanks,
tglx
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