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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Generic UP xchg and cmpxchg using interrupt disablement. Does not
* support SMP.
*/
#ifndef __ASM_GENERIC_CMPXCHG_H
#define __ASM_GENERIC_CMPXCHG_H
#ifdef CONFIG_SMP
#error "Cannot use generic cmpxchg on SMP"
#endif
#include <linux/types.h>
#include <linux/irqflags.h>
/*
* This function doesn't exist, so you'll get a linker error if
* something tries to do an invalidly-sized xchg().
*/
extern void __generic_xchg_called_with_bad_pointer(void);
static inline
unsigned long __generic_xchg(unsigned long x, volatile void *ptr, int size)
{
unsigned long ret, flags;
switch (size) {
case 1:
#ifdef __xchg_u8
return __xchg_u8(x, ptr);
#else
local_irq_save(flags);
ret = *(volatile u8 *)ptr;
*(volatile u8 *)ptr = (x & 0xffu);
local_irq_restore(flags);
return ret;
#endif /* __xchg_u8 */
case 2:
#ifdef __xchg_u16
return __xchg_u16(x, ptr);
#else
local_irq_save(flags);
ret = *(volatile u16 *)ptr;
*(volatile u16 *)ptr = (x & 0xffffu);
local_irq_restore(flags);
return ret;
#endif /* __xchg_u16 */
case 4:
#ifdef __xchg_u32
return __xchg_u32(x, ptr);
#else
local_irq_save(flags);
ret = *(volatile u32 *)ptr;
*(volatile u32 *)ptr = (x & 0xffffffffu);
local_irq_restore(flags);
return ret;
#endif /* __xchg_u32 */
#ifdef CONFIG_64BIT
case 8:
#ifdef __xchg_u64
return __xchg_u64(x, ptr);
#else
local_irq_save(flags);
ret = *(volatile u64 *)ptr;
*(volatile u64 *)ptr = x;
local_irq_restore(flags);
return ret;
#endif /* __xchg_u64 */
#endif /* CONFIG_64BIT */
default:
__generic_xchg_called_with_bad_pointer();
return x;
}
}
#define generic_xchg(ptr, x) ({ \
((__typeof__(*(ptr))) \
__generic_xchg((unsigned long)(x), (ptr), sizeof(*(ptr)))); \
})
/*
* Atomic compare and exchange.
*/
#include <asm-generic/cmpxchg-local.h>
#define generic_cmpxchg_local(ptr, o, n) ({ \
((__typeof__(*(ptr)))__generic_cmpxchg_local((ptr), (unsigned long)(o), \
(unsigned long)(n), sizeof(*(ptr)))); \
})
#define generic_cmpxchg64_local(ptr, o, n) \
__generic_cmpxchg64_local((ptr), (o), (n))
#ifndef arch_xchg
#define arch_xchg generic_xchg
#endif
#ifndef arch_cmpxchg_local
#define arch_cmpxchg_local generic_cmpxchg_local
#endif
#ifndef arch_cmpxchg64_local
#define arch_cmpxchg64_local generic_cmpxchg64_local
#endif
#define arch_cmpxchg arch_cmpxchg_local
#define arch_cmpxchg64 arch_cmpxchg64_local
#endif /* __ASM_GENERIC_CMPXCHG_H */
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