1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* 32-bit atomic xchg() and cmpxchg() definitions.
3  *
4  * Copyright (C) 1996 David S. Miller (davem@davemloft.net)
5  * Copyright (C) 2000 Anton Blanchard (anton@linuxcare.com.au)
6  * Copyright (C) 2007 Kyle McMartin (kyle@parisc-linux.org)
7  *
8  * Additions by Keith M Wesolowski (wesolows@foobazco.org) based
9  * on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>.
10  */
11 
12 #ifndef __ARCH_SPARC_CMPXCHG__
13 #define __ARCH_SPARC_CMPXCHG__
14 
15 unsigned long __xchg_u32(volatile u32 *m, u32 new);
16 void __xchg_called_with_bad_pointer(void);
17 
18 static __always_inline unsigned long __arch_xchg(unsigned long x, __volatile__ void * ptr, int size)
19 {
20 	switch (size) {
21 	case 4:
22 		return __xchg_u32(ptr, x);
23 	}
24 	__xchg_called_with_bad_pointer();
25 	return x;
26 }
27 
28 #define arch_xchg(ptr,x) ({(__typeof__(*(ptr)))__arch_xchg((unsigned long)(x),(ptr),sizeof(*(ptr)));})
29 
30 /* Emulate cmpxchg() the same way we emulate atomics,
31  * by hashing the object address and indexing into an array
32  * of spinlocks to get a bit of performance...
33  *
34  * See arch/sparc/lib/atomic32.c for implementation.
35  *
36  * Cribbed from <asm-parisc/atomic.h>
37  */
38 
39 /* bug catcher for when unsupported size is used - won't link */
40 void __cmpxchg_called_with_bad_pointer(void);
41 /* we only need to support cmpxchg of a u32 on sparc */
42 unsigned long __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
43 
44 /* don't worry...optimizer will get rid of most of this */
45 static inline unsigned long
46 __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
47 {
48 	switch (size) {
49 	case 4:
50 		return __cmpxchg_u32((u32 *)ptr, (u32)old, (u32)new_);
51 	default:
52 		__cmpxchg_called_with_bad_pointer();
53 		break;
54 	}
55 	return old;
56 }
57 
58 #define arch_cmpxchg(ptr, o, n)						\
59 ({									\
60 	__typeof__(*(ptr)) _o_ = (o);					\
61 	__typeof__(*(ptr)) _n_ = (n);					\
62 	(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,	\
63 			(unsigned long)_n_, sizeof(*(ptr)));		\
64 })
65 
66 u64 __cmpxchg_u64(u64 *ptr, u64 old, u64 new);
67 #define arch_cmpxchg64(ptr, old, new)	__cmpxchg_u64(ptr, old, new)
68 
69 #include <asm-generic/cmpxchg-local.h>
70 
71 /*
72  * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
73  * them available.
74  */
75 #define arch_cmpxchg_local(ptr, o, n)				  	       \
76 	((__typeof__(*(ptr)))__generic_cmpxchg_local((ptr), (unsigned long)(o),\
77 			(unsigned long)(n), sizeof(*(ptr))))
78 #define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
79 
80 #endif /* __ARCH_SPARC_CMPXCHG__ */
81