bitops.c

// SPDX-License-Identifier: GPL-2.0
/*
 * bitops.c: atomic operations which got too long to be inlined all over
 *      the place.
 * 
 * Copyright 1999 Philipp Rumpf ([email protected])
 * Copyright 2000 Grant Grundler ([email protected])
 */

#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>

#ifdef CONFIG_SMP
arch_spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] __lock_aligned = {
	[0 ... (ATOMIC_HASH_SIZE-1)]  = __ARCH_SPIN_LOCK_UNLOCKED
};
#endif

#ifdef CONFIG_64BIT
unsigned long notrace __xchg64(unsigned long x, volatile unsigned long *ptr)
{
	unsigned long temp, flags;

	_atomic_spin_lock_irqsave(ptr, flags);
	temp = *ptr;
	*ptr = x;
	_atomic_spin_unlock_irqrestore(ptr, flags);
	return temp;
}
#endif

unsigned long notrace __xchg32(int x, volatile int *ptr)
{
	unsigned long flags;
	long temp;

	_atomic_spin_lock_irqsave(ptr, flags);
	temp = (long) *ptr;	/* XXX - sign extension wanted? */
	*ptr = x;
	_atomic_spin_unlock_irqrestore(ptr, flags);
	return (unsigned long)temp;
}


unsigned long notrace __xchg8(char x, volatile char *ptr)
{
	unsigned long flags;
	long temp;

	_atomic_spin_lock_irqsave(ptr, flags);
	temp = (long) *ptr;	/* XXX - sign extension wanted? */
	*ptr = x;
	_atomic_spin_unlock_irqrestore(ptr, flags);
	return (unsigned long)temp;
}


#define CMPXCHG(T)						\
	T notrace __cmpxchg_##T(volatile T *ptr, T old, T new)	\
	{							\
		unsigned long flags;				\
		T prev;						\
								\
		_atomic_spin_lock_irqsave(ptr, flags);		\
		if ((prev = *ptr) == old)			\
			*ptr = new;				\
		_atomic_spin_unlock_irqrestore(ptr, flags);	\
		return prev;					\
	}

CMPXCHG(u64)
CMPXCHG(u32)
CMPXCHG(u16)
CMPXCHG(u8)