bitops.c

 1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * bitops.c: atomic operations which got too long to be inlined all over
 4 *      the place.
 5 * 
 6 * Copyright 1999 Philipp Rumpf (prumpf@tux.org)
 7 * Copyright 2000 Grant Grundler (grundler@cup.hp.com)
 8 */
 9
10#include <linux/kernel.h>
11#include <linux/spinlock.h>
12#include <linux/atomic.h>
13
14#ifdef CONFIG_SMP
15arch_spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] __lock_aligned = {
16	[0 ... (ATOMIC_HASH_SIZE-1)]  = __ARCH_SPIN_LOCK_UNLOCKED
17};
18#endif
19
20#ifdef CONFIG_64BIT
21unsigned long notrace __xchg64(unsigned long x, volatile unsigned long *ptr)
22{
23	unsigned long temp, flags;
24
25	_atomic_spin_lock_irqsave(ptr, flags);
26	temp = *ptr;
27	*ptr = x;
28	_atomic_spin_unlock_irqrestore(ptr, flags);
29	return temp;
30}
31#endif
32
33unsigned long notrace __xchg32(int x, volatile int *ptr)
34{
35	unsigned long flags;
36	long temp;
37
38	_atomic_spin_lock_irqsave(ptr, flags);
39	temp = (long) *ptr;	/* XXX - sign extension wanted? */
40	*ptr = x;
41	_atomic_spin_unlock_irqrestore(ptr, flags);
42	return (unsigned long)temp;
43}
44
45
46unsigned long notrace __xchg8(char x, volatile char *ptr)
47{
48	unsigned long flags;
49	long temp;
50
51	_atomic_spin_lock_irqsave(ptr, flags);
52	temp = (long) *ptr;	/* XXX - sign extension wanted? */
53	*ptr = x;
54	_atomic_spin_unlock_irqrestore(ptr, flags);
55	return (unsigned long)temp;
56}
57
58
59#define CMPXCHG(T)						\
60	T notrace __cmpxchg_##T(volatile T *ptr, T old, T new)	\
61	{							\
62		unsigned long flags;				\
63		T prev;						\
64								\
65		_atomic_spin_lock_irqsave(ptr, flags);		\
66		if ((prev = *ptr) == old)			\
67			*ptr = new;				\
68		_atomic_spin_unlock_irqrestore(ptr, flags);	\
69		return prev;					\
70	}
71
72CMPXCHG(u64)
73CMPXCHG(u32)
74CMPXCHG(u16)
75CMPXCHG(u8)