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/*
* Based on arch/arm/include/asm/cmpxchg.h
*
* Copyright (C) 2012 ARM Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __ASM_CMPXCHG_H
#define __ASM_CMPXCHG_H
#include <linux/bug.h>
#include <asm/barrier.h>
static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
{
unsigned long ret, tmp;
switch (size) {
case 1:
asm volatile("// __xchg1\n"
"1: ldaxrb %w0, %2\n"
" stlxrb %w1, %w3, %2\n"
" cbnz %w1, 1b\n"
: "=&r" (ret), "=&r" (tmp), "+Q" (*(u8 *)ptr)
: "r" (x)
: "cc", "memory");
break;
case 2:
asm volatile("// __xchg2\n"
"1: ldaxrh %w0, %2\n"
" stlxrh %w1, %w3, %2\n"
" cbnz %w1, 1b\n"
: "=&r" (ret), "=&r" (tmp), "+Q" (*(u16 *)ptr)
: "r" (x)
: "cc", "memory");
break;
case 4:
asm volatile("// __xchg4\n"
"1: ldaxr %w0, %2\n"
" stlxr %w1, %w3, %2\n"
" cbnz %w1, 1b\n"
: "=&r" (ret), "=&r" (tmp), "+Q" (*(u32 *)ptr)
: "r" (x)
: "cc", "memory");
break;
case 8:
asm volatile("// __xchg8\n"
"1: ldaxr %0, %2\n"
" stlxr %w1, %3, %2\n"
" cbnz %w1, 1b\n"
: "=&r" (ret), "=&r" (tmp), "+Q" (*(u64 *)ptr)
: "r" (x)
: "cc", "memory");
break;
default:
BUILD_BUG();
}
return ret;
}
#define xchg(ptr,x) \
((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
unsigned long new, int size)
{
unsigned long oldval = 0, res;
switch (size) {
case 1:
do {
asm volatile("// __cmpxchg1\n"
" ldxrb %w1, %2\n"
" mov %w0, #0\n"
" cmp %w1, %w3\n"
" b.ne 1f\n"
" stxrb %w0, %w4, %2\n"
"1:\n"
: "=&r" (res), "=&r" (oldval), "+Q" (*(u8 *)ptr)
: "Ir" (old), "r" (new)
: "cc");
} while (res);
break;
case 2:
do {
asm volatile("// __cmpxchg2\n"
" ldxrh %w1, %2\n"
" mov %w0, #0\n"
" cmp %w1, %w3\n"
" b.ne 1f\n"
" stxrh %w0, %w4, %2\n"
"1:\n"
: "=&r" (res), "=&r" (oldval), "+Q" (*(u16 *)ptr)
: "Ir" (old), "r" (new)
: "cc");
} while (res);
break;
case 4:
do {
asm volatile("// __cmpxchg4\n"
" ldxr %w1, %2\n"
" mov %w0, #0\n"
" cmp %w1, %w3\n"
" b.ne 1f\n"
" stxr %w0, %w4, %2\n"
"1:\n"
: "=&r" (res), "=&r" (oldval), "+Q" (*(u32 *)ptr)
: "Ir" (old), "r" (new)
: "cc");
} while (res);
break;
case 8:
do {
asm volatile("// __cmpxchg8\n"
" ldxr %1, %2\n"
" mov %w0, #0\n"
" cmp %1, %3\n"
" b.ne 1f\n"
" stxr %w0, %4, %2\n"
"1:\n"
: "=&r" (res), "=&r" (oldval), "+Q" (*(u64 *)ptr)
: "Ir" (old), "r" (new)
: "cc");
} while (res);
break;
default:
BUILD_BUG();
}
return oldval;
}
static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old,
unsigned long new, int size)
{
unsigned long ret;
smp_mb();
ret = __cmpxchg(ptr, old, new, size);
smp_mb();
return ret;
}
#define cmpxchg(ptr,o,n) \
((__typeof__(*(ptr)))__cmpxchg_mb((ptr), \
(unsigned long)(o), \
(unsigned long)(n), \
sizeof(*(ptr))))
#define cmpxchg_local(ptr,o,n) \
((__typeof__(*(ptr)))__cmpxchg((ptr), \
(unsigned long)(o), \
(unsigned long)(n), \
sizeof(*(ptr))))
#endif /* __ASM_CMPXCHG_H */
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