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/* SPDX-License-Identifier: GPL-2.0 */
/* 64-bit atomic xchg() and cmpxchg() definitions.
*
* Copyright (C) 1996, 1997, 2000 David S. Miller (davem@redhat.com)
*/
#ifndef __ARCH_SPARC64_CMPXCHG__
#define __ARCH_SPARC64_CMPXCHG__
static inline unsigned long
__cmpxchg_u32(volatile int *m, int old, int new)
{
__asm__ __volatile__("cas [%2], %3, %0"
: "=&r" (new)
: "0" (new), "r" (m), "r" (old)
: "memory");
return new;
}
static inline unsigned long xchg32(__volatile__ unsigned int *m, unsigned int val)
{
unsigned long tmp1, tmp2;
__asm__ __volatile__(
" mov %0, %1\n"
"1: lduw [%4], %2\n"
" cas [%4], %2, %0\n"
" cmp %2, %0\n"
" bne,a,pn %%icc, 1b\n"
" mov %1, %0\n"
: "=&r" (val), "=&r" (tmp1), "=&r" (tmp2)
: "0" (val), "r" (m)
: "cc", "memory");
return val;
}
static inline unsigned long xchg64(__volatile__ unsigned long *m, unsigned long val)
{
unsigned long tmp1, tmp2;
__asm__ __volatile__(
" mov %0, %1\n"
"1: ldx [%4], %2\n"
" casx [%4], %2, %0\n"
" cmp %2, %0\n"
" bne,a,pn %%xcc, 1b\n"
" mov %1, %0\n"
: "=&r" (val), "=&r" (tmp1), "=&r" (tmp2)
: "0" (val), "r" (m)
: "cc", "memory");
return val;
}
#define xchg(ptr,x) \
({ __typeof__(*(ptr)) __ret; \
__ret = (__typeof__(*(ptr))) \
__xchg((unsigned long)(x), (ptr), sizeof(*(ptr))); \
__ret; \
})
void __xchg_called_with_bad_pointer(void);
/*
* Use 4 byte cas instruction to achieve 2 byte xchg. Main logic
* here is to get the bit shift of the byte we are interested in.
* The XOR is handy for reversing the bits for big-endian byte order.
*/
static inline unsigned long
xchg16(__volatile__ unsigned short *m, unsigned short val)
{
unsigned long maddr = (unsigned long)m;
int bit_shift = (((unsigned long)m & 2) ^ 2) << 3;
unsigned int mask = 0xffff << bit_shift;
unsigned int *ptr = (unsigned int *) (maddr & ~2);
unsigned int old32, new32, load32;
/* Read the old value */
load32 = *ptr;
do {
old32 = load32;
new32 = (load32 & (~mask)) | val << bit_shift;
load32 = __cmpxchg_u32(ptr, old32, new32);
} while (load32 != old32);
return (load32 & mask) >> bit_shift;
}
static inline unsigned long __xchg(unsigned long x, __volatile__ void * ptr,
int size)
{
switch (size) {
case 2:
return xchg16(ptr, x);
case 4:
return xchg32(ptr, x);
case 8:
return xchg64(ptr, x);
}
__xchg_called_with_bad_pointer();
return x;
}
/*
* Atomic compare and exchange. Compare OLD with MEM, if identical,
* store NEW in MEM. Return the initial value in MEM. Success is
* indicated by comparing RETURN with OLD.
*/
#include <asm-generic/cmpxchg-local.h>
static inline unsigned long
__cmpxchg_u64(volatile long *m, unsigned long old, unsigned long new)
{
__asm__ __volatile__("casx [%2], %3, %0"
: "=&r" (new)
: "0" (new), "r" (m), "r" (old)
: "memory");
return new;
}
/*
* Use 4 byte cas instruction to achieve 1 byte cmpxchg. Main logic
* here is to get the bit shift of the byte we are interested in.
* The XOR is handy for reversing the bits for big-endian byte order
*/
static inline unsigned long
__cmpxchg_u8(volatile unsigned char *m, unsigned char old, unsigned char new)
{
unsigned long maddr = (unsigned long)m;
int bit_shift = (((unsigned long)m & 3) ^ 3) << 3;
unsigned int mask = 0xff << bit_shift;
unsigned int *ptr = (unsigned int *) (maddr & ~3);
unsigned int old32, new32, load;
unsigned int load32 = *ptr;
do {
new32 = (load32 & ~mask) | (new << bit_shift);
old32 = (load32 & ~mask) | (old << bit_shift);
load32 = __cmpxchg_u32(ptr, old32, new32);
if (load32 == old32)
return old;
load = (load32 & mask) >> bit_shift;
} while (load == old);
return load;
}
/* This function doesn't exist, so you'll get a linker error
if something tries to do an invalid cmpxchg(). */
void __cmpxchg_called_with_bad_pointer(void);
static inline unsigned long
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
{
switch (size) {
case 1:
return __cmpxchg_u8(ptr, old, new);
case 4:
return __cmpxchg_u32(ptr, old, new);
case 8:
return __cmpxchg_u64(ptr, old, new);
}
__cmpxchg_called_with_bad_pointer();
return old;
}
#define cmpxchg(ptr,o,n) \
({ \
__typeof__(*(ptr)) _o_ = (o); \
__typeof__(*(ptr)) _n_ = (n); \
(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_, \
(unsigned long)_n_, sizeof(*(ptr))); \
})
/*
* cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
* them available.
*/
static inline unsigned long __cmpxchg_local(volatile void *ptr,
unsigned long old,
unsigned long new, int size)
{
switch (size) {
case 4:
case 8: return __cmpxchg(ptr, old, new, size);
default:
return __cmpxchg_local_generic(ptr, old, new, size);
}
return old;
}
#define cmpxchg_local(ptr, o, n) \
((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o), \
(unsigned long)(n), sizeof(*(ptr))))
#define cmpxchg64_local(ptr, o, n) \
({ \
BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
cmpxchg_local((ptr), (o), (n)); \
})
#define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n))
#endif /* __ARCH_SPARC64_CMPXCHG__ */
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