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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
*/
#ifndef __ASM_CMPXCHG_H
#define __ASM_CMPXCHG_H
#include <linux/bits.h>
#include <linux/build_bug.h>
#include <asm/barrier.h>
#define __xchg_asm(amswap_db, m, val) \
({ \
__typeof(val) __ret; \
\
__asm__ __volatile__ ( \
" "amswap_db" %1, %z2, %0 \n" \
: "+ZB" (*m), "=&r" (__ret) \
: "Jr" (val) \
: "memory"); \
\
__ret; \
})
static inline unsigned int __xchg_small(volatile void *ptr, unsigned int val,
unsigned int size)
{
unsigned int shift;
u32 old32, mask, temp;
volatile u32 *ptr32;
/* Mask value to the correct size. */
mask = GENMASK((size * BITS_PER_BYTE) - 1, 0);
val &= mask;
/*
* Calculate a shift & mask that correspond to the value we wish to
* exchange within the naturally aligned 4 byte integerthat includes
* it.
*/
shift = (unsigned long)ptr & 0x3;
shift *= BITS_PER_BYTE;
mask <<= shift;
/*
* Calculate a pointer to the naturally aligned 4 byte integer that
* includes our byte of interest, and load its value.
*/
ptr32 = (volatile u32 *)((unsigned long)ptr & ~0x3);
asm volatile (
"1: ll.w %0, %3 \n"
" andn %1, %0, %z4 \n"
" or %1, %1, %z5 \n"
" sc.w %1, %2 \n"
" beqz %1, 1b \n"
: "=&r" (old32), "=&r" (temp), "=ZC" (*ptr32)
: "ZC" (*ptr32), "Jr" (mask), "Jr" (val << shift)
: "memory");
return (old32 & mask) >> shift;
}
static __always_inline unsigned long
__arch_xchg(volatile void *ptr, unsigned long x, int size)
{
switch (size) {
case 1:
case 2:
return __xchg_small(ptr, x, size);
case 4:
return __xchg_asm("amswap_db.w", (volatile u32 *)ptr, (u32)x);
case 8:
return __xchg_asm("amswap_db.d", (volatile u64 *)ptr, (u64)x);
default:
BUILD_BUG();
}
return 0;
}
#define arch_xchg(ptr, x) \
({ \
__typeof__(*(ptr)) __res; \
\
__res = (__typeof__(*(ptr))) \
__arch_xchg((ptr), (unsigned long)(x), sizeof(*(ptr))); \
\
__res; \
})
#define __cmpxchg_asm(ld, st, m, old, new) \
({ \
__typeof(old) __ret; \
\
__asm__ __volatile__( \
"1: " ld " %0, %2 # __cmpxchg_asm \n" \
" bne %0, %z3, 2f \n" \
" move $t0, %z4 \n" \
" " st " $t0, %1 \n" \
" beqz $t0, 1b \n" \
"2: \n" \
__WEAK_LLSC_MB \
: "=&r" (__ret), "=ZB"(*m) \
: "ZB"(*m), "Jr" (old), "Jr" (new) \
: "t0", "memory"); \
\
__ret; \
})
static inline unsigned int __cmpxchg_small(volatile void *ptr, unsigned int old,
unsigned int new, unsigned int size)
{
unsigned int shift;
u32 old32, mask, temp;
volatile u32 *ptr32;
/* Mask inputs to the correct size. */
mask = GENMASK((size * BITS_PER_BYTE) - 1, 0);
old &= mask;
new &= mask;
/*
* Calculate a shift & mask that correspond to the value we wish to
* compare & exchange within the naturally aligned 4 byte integer
* that includes it.
*/
shift = (unsigned long)ptr & 0x3;
shift *= BITS_PER_BYTE;
old <<= shift;
new <<= shift;
mask <<= shift;
/*
* Calculate a pointer to the naturally aligned 4 byte integer that
* includes our byte of interest, and load its value.
*/
ptr32 = (volatile u32 *)((unsigned long)ptr & ~0x3);
asm volatile (
"1: ll.w %0, %3 \n"
" and %1, %0, %z4 \n"
" bne %1, %z5, 2f \n"
" andn %1, %0, %z4 \n"
" or %1, %1, %z6 \n"
" sc.w %1, %2 \n"
" beqz %1, 1b \n"
" b 3f \n"
"2: \n"
__WEAK_LLSC_MB
"3: \n"
: "=&r" (old32), "=&r" (temp), "=ZC" (*ptr32)
: "ZC" (*ptr32), "Jr" (mask), "Jr" (old), "Jr" (new)
: "memory");
return (old32 & mask) >> shift;
}
static __always_inline unsigned long
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, unsigned int size)
{
switch (size) {
case 1:
case 2:
return __cmpxchg_small(ptr, old, new, size);
case 4:
return __cmpxchg_asm("ll.w", "sc.w", (volatile u32 *)ptr,
(u32)old, new);
case 8:
return __cmpxchg_asm("ll.d", "sc.d", (volatile u64 *)ptr,
(u64)old, new);
default:
BUILD_BUG();
}
return 0;
}
#define arch_cmpxchg_local(ptr, old, new) \
((__typeof__(*(ptr))) \
__cmpxchg((ptr), \
(unsigned long)(__typeof__(*(ptr)))(old), \
(unsigned long)(__typeof__(*(ptr)))(new), \
sizeof(*(ptr))))
#define arch_cmpxchg(ptr, old, new) \
({ \
__typeof__(*(ptr)) __res; \
\
__res = arch_cmpxchg_local((ptr), (old), (new)); \
\
__res; \
})
#ifdef CONFIG_64BIT
#define arch_cmpxchg64_local(ptr, o, n) \
({ \
BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
arch_cmpxchg_local((ptr), (o), (n)); \
})
#define arch_cmpxchg64(ptr, o, n) \
({ \
BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
arch_cmpxchg((ptr), (o), (n)); \
})
#else
#include <asm-generic/cmpxchg-local.h>
#define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
#define arch_cmpxchg64(ptr, o, n) arch_cmpxchg64_local((ptr), (o), (n))
#endif
#endif /* __ASM_CMPXCHG_H */
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