include/asm/cmpxchg_32.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 /* 32-bit atomic xchg() and cmpxchg() definitions.
0003  *
0004  * Copyright (C) 1996 David S. Miller (davem@davemloft.net)
0005  * Copyright (C) 2000 Anton Blanchard (anton@linuxcare.com.au)
0006  * Copyright (C) 2007 Kyle McMartin (kyle@parisc-linux.org)
0007  *
0008  * Additions by Keith M Wesolowski (wesolows@foobazco.org) based
0009  * on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>.
0010  */
0011
0012 #ifndef __ARCH_SPARC_CMPXCHG__
0013 #define __ARCH_SPARC_CMPXCHG__
0014
0015 unsigned long __xchg_u32(volatile u32 *m, u32 new);
0016 void __xchg_called_with_bad_pointer(void);
0017
0018 static inline unsigned long __xchg(unsigned long x, __volatile__ void * ptr, int size)
0019 {
0020     switch (size) {
0021     case 4:
0022         return __xchg_u32(ptr, x);
0023     }
0024     __xchg_called_with_bad_pointer();
0025     return x;
0026 }
0027
0028 #define arch_xchg(ptr,x) ({(__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr)));})
0029
0030 /* Emulate cmpxchg() the same way we emulate atomics,
0031  * by hashing the object address and indexing into an array
0032  * of spinlocks to get a bit of performance...
0033  *
0034  * See arch/sparc/lib/atomic32.c for implementation.
0035  *
0036  * Cribbed from <asm-parisc/atomic.h>
0037  */
0038
0039 /* bug catcher for when unsupported size is used - won't link */
0040 void __cmpxchg_called_with_bad_pointer(void);
0041 /* we only need to support cmpxchg of a u32 on sparc */
0042 unsigned long __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
0043
0044 /* don't worry...optimizer will get rid of most of this */
0045 static inline unsigned long
0046 __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
0047 {
0048     switch (size) {
0049     case 4:
0050         return __cmpxchg_u32((u32 *)ptr, (u32)old, (u32)new_);
0051     default:
0052         __cmpxchg_called_with_bad_pointer();
0053         break;
0054     }
0055     return old;
0056 }
0057
0058 #define arch_cmpxchg(ptr, o, n)                     \
0059 ({                                  \
0060     __typeof__(*(ptr)) _o_ = (o);                   \
0061     __typeof__(*(ptr)) _n_ = (n);                   \
0062     (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,   \
0063             (unsigned long)_n_, sizeof(*(ptr)));        \
0064 })
0065
0066 u64 __cmpxchg_u64(u64 *ptr, u64 old, u64 new);
0067 #define arch_cmpxchg64(ptr, old, new)   __cmpxchg_u64(ptr, old, new)
0068
0069 #include <asm-generic/cmpxchg-local.h>
0070
0071 /*
0072  * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
0073  * them available.
0074  */
0075 #define arch_cmpxchg_local(ptr, o, n)                          \
0076     ((__typeof__(*(ptr)))__generic_cmpxchg_local((ptr), (unsigned long)(o),\
0077             (unsigned long)(n), sizeof(*(ptr))))
0078 #define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
0079
0080 #endif /* __ARCH_SPARC_CMPXCHG__ */