cmpxchg.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * forked from parisc asm/atomic.h which was:
  4 *	Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>
  5 *	Copyright (C) 2006 Kyle McMartin <kyle@parisc-linux.org>
  6 */
  7
  8#ifndef _ASM_PARISC_CMPXCHG_H_
  9#define _ASM_PARISC_CMPXCHG_H_
 10
 11/* This should get optimized out since it's never called.
 12** Or get a link error if xchg is used "wrong".
 13*/
 14extern void __xchg_called_with_bad_pointer(void);
 15
 16/* __xchg32/64 defined in arch/parisc/lib/bitops.c */
 17extern unsigned long __xchg8(char, volatile char *);
 18extern unsigned long __xchg32(int, volatile int *);
 19#ifdef CONFIG_64BIT
 20extern unsigned long __xchg64(unsigned long, volatile unsigned long *);
 21#endif
 22
 23/* optimizer better get rid of switch since size is a constant */
 24static inline unsigned long
 25__arch_xchg(unsigned long x, volatile void *ptr, int size)
 26{
 27	switch (size) {
 28#ifdef CONFIG_64BIT
 29	case 8: return __xchg64(x, (volatile unsigned long *) ptr);
 30#endif
 31	case 4: return __xchg32((int) x, (volatile int *) ptr);
 32	case 1: return __xchg8((char) x, (volatile char *) ptr);
 33	}
 34	__xchg_called_with_bad_pointer();
 35	return x;
 36}
 37
 38/*
 39** REVISIT - Abandoned use of LDCW in xchg() for now:
 40** o need to test sizeof(*ptr) to avoid clearing adjacent bytes
 41** o and while we are at it, could CONFIG_64BIT code use LDCD too?
 42**
 43**	if (__builtin_constant_p(x) && (x == NULL))
 44**		if (((unsigned long)p & 0xf) == 0)
 45**			return __ldcw(p);
 46*/
 47#define arch_xchg(ptr, x)						\
 48({									\
 49	__typeof__(*(ptr)) __ret;					\
 50	__typeof__(*(ptr)) _x_ = (x);					\
 51	__ret = (__typeof__(*(ptr)))					\
 52		__arch_xchg((unsigned long)_x_, (ptr), sizeof(*(ptr)));	\
 53	__ret;								\
 54})
 55
 56/* bug catcher for when unsupported size is used - won't link */
 57extern void __cmpxchg_called_with_bad_pointer(void);
 58
 59/* __cmpxchg_u... defined in arch/parisc/lib/bitops.c */
 60extern u8 __cmpxchg_u8(volatile u8 *ptr, u8 old, u8 new_);
 61extern u16 __cmpxchg_u16(volatile u16 *ptr, u16 old, u16 new_);
 62extern u32 __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
 63extern u64 __cmpxchg_u64(volatile u64 *ptr, u64 old, u64 new_);
 64
 65/* don't worry...optimizer will get rid of most of this */
 66static inline unsigned long
 67__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
 68{
 69	return
 70#ifdef CONFIG_64BIT
 71		size == 8 ? __cmpxchg_u64(ptr, old, new_) :
 72#endif
 73		size == 4 ? __cmpxchg_u32(ptr, old, new_) :
 74		size == 2 ? __cmpxchg_u16(ptr, old, new_) :
 75		size == 1 ? __cmpxchg_u8(ptr, old, new_) :
 76			(__cmpxchg_called_with_bad_pointer(), old);
 77}
 78
 79#define arch_cmpxchg(ptr, o, n)						 \
 80({									 \
 81	__typeof__(*(ptr)) _o_ = (o);					 \
 82	__typeof__(*(ptr)) _n_ = (n);					 \
 83	(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,	 \
 84				    (unsigned long)_n_, sizeof(*(ptr))); \
 85})
 86
 87#include <asm-generic/cmpxchg-local.h>
 88
 89static inline unsigned long __cmpxchg_local(volatile void *ptr,
 90				      unsigned long old,
 91				      unsigned long new_, int size)
 92{
 93	switch (size) {
 94#ifdef CONFIG_64BIT
 95	case 8:	return __cmpxchg_u64((u64 *)ptr, old, new_);
 96#endif
 97	case 4:	return __cmpxchg_u32(ptr, old, new_);
 98	default:
 99		return __generic_cmpxchg_local(ptr, old, new_, size);
100	}
101}
102
103/*
104 * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
105 * them available.
106 */
107#define arch_cmpxchg_local(ptr, o, n)					\
108	((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o),	\
109			(unsigned long)(n), sizeof(*(ptr))))
110#ifdef CONFIG_64BIT
111#define arch_cmpxchg64_local(ptr, o, n)					\
112({									\
113	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
114	cmpxchg_local((ptr), (o), (n));					\
115})
116#else
117#define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
118#endif
119
120#define arch_cmpxchg64(ptr, o, n) __cmpxchg_u64(ptr, o, n)
121
122#endif /* _ASM_PARISC_CMPXCHG_H_ */