/*
* Based on arch/arm/include/asm/atomic.h
*
* Copyright (C) 1996 Russell King.
* Copyright (C) 2002 Deep Blue Solutions Ltd.
* 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_ATOMIC_LL_SC_H
#define __ASM_ATOMIC_LL_SC_H
/*
* AArch64 UP and SMP safe atomic ops. We use load exclusive and
* store exclusive to ensure that these are atomic. We may loop
* to ensure that the update happens.
*
* NOTE: these functions do *not* follow the PCS and must explicitly
* save any clobbered registers other than x0 (regardless of return
* value). This is achieved through -fcall-saved-* compiler flags for
* this file, which unfortunately don't work on a per-function basis
* (the optimize attribute silently ignores these options).
*/
#ifndef __LL_SC_INLINE
#define __LL_SC_INLINE static inline
#endif
#ifndef __LL_SC_PREFIX
#define __LL_SC_PREFIX(x) x
#endif
#define ATOMIC_OP(op, asm_op) \
__LL_SC_INLINE void \
__LL_SC_PREFIX(atomic_##op(int i, atomic_t *v)) \
{ \
unsigned long tmp; \
int result; \
\
asm volatile("// atomic_" #op "\n" \
"1: ldxr %w0, %2\n" \
" " #asm_op " %w0, %w0, %w3\n" \
" stxr %w1, %w0, %2\n" \
" cbnz %w1, 1b" \
: "=&r" (result), "=&r" (tmp), "+Q" (v->counter) \
: "Ir" (i)); \
} \
#define ATOMIC_OP_RETURN(op, asm_op) \
__LL_SC_INLINE int \
__LL_SC_PREFIX(atomic_##op##_return(int i, atomic_t *v)) \
{ \
unsigned long tmp; \
int result; \
\
asm volatile("// atomic_" #op "_return\n" \
"1: ldxr %w0, %2\n" \
" " #asm_op " %w0, %w0, %w3\n" \
" stlxr %w1, %w0, %2\n" \
" cbnz %w1, 1b" \
: "=&r" (result), "=&r" (tmp), "+Q" (v->counter) \
: "Ir" (i) \
: "memory"); \
\
smp_mb(); \
return result; \
}
#define ATOMIC_OPS(op, asm_op) \
ATOMIC_OP(op, asm_op) \
ATOMIC_OP_RETURN(op, asm_op)
ATOMIC_OPS(add, add)
ATOMIC_OPS(sub, sub)
ATOMIC_OP(and, and)
ATOMIC_OP(andnot, bic)
ATOMIC_OP(or, orr)
ATOMIC_OP(xor, eor)
#undef ATOMIC_OPS
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
__LL_SC_INLINE int
__LL_SC_PREFIX(atomic_cmpxchg(atomic_t *ptr, int old, int new))
{
unsigned long tmp;
int oldval;
smp_mb();
asm volatile("// atomic_cmpxchg\n"
"1: ldxr %w1, %2\n"
" cmp %w1, %w3\n"
" b.ne 2f\n"
" stxr %w0, %w4, %2\n"
" cbnz %w0, 1b\n"
"2:"
: "=&r" (tmp), "=&r" (oldval), "+Q" (ptr->counter)
: "Ir" (old), "r" (new)
: "cc");
smp_mb();
return oldval;
}
#define ATOMIC64_OP(op, asm_op) \
__LL_SC_INLINE void \
__LL_SC_PREFIX(atomic64_##op(long i, atomic64_t *v)) \
{ \
long result; \
unsigned long tmp; \
\
asm volatile("// atomic64_" #op "\n" \
"1: ldxr %0, %2\n" \
" " #asm_op " %0, %0, %3\n" \
" stxr %w1, %0, %2\n" \
" cbnz %w1, 1b" \
: "=&r" (result), "=&r" (tmp), "+Q" (v->counter) \
: "Ir" (i)); \
} \
#define ATOMIC64_OP_RETURN(op, asm_op) \
__LL_SC_INLINE long \
__LL_SC_PREFIX(atomic64_##op##_return(long i, atomic64_t *v)) \
{ \
long result; \
unsigned long tmp; \
\
asm volatile("// atomic64_" #op "_return\n" \
"1: ldxr %0, %2\n" \
" " #asm_op " %0, %0, %3\n" \
" stlxr %w1, %0, %2\n" \
" cbnz %w1, 1b" \
: "=&r" (result), "=&r" (tmp), "+Q" (v->counter) \
: "Ir" (i) \
: "memory"); \
\
smp_mb(); \
return result; \
}
#define ATOMIC64_OPS(op, asm_op) \
ATOMIC64_OP(op, asm_op) \
ATOMIC64_OP_RETURN(op, asm_op)
ATOMIC64_OPS(add, add)
ATOMIC64_OPS(sub, sub)
ATOMIC64_OP(and, and)
ATOMIC64_OP(andnot, bic)
ATOMIC64_OP(or, orr)
ATOMIC64_OP(xor, eor)
#undef ATOMIC64_OPS
#undef ATOMIC64_OP_RETURN
#undef ATOMIC64_OP
__LL_SC_INLINE long
__LL_SC_PREFIX(atomic64_cmpxchg(atomic64_t *ptr, long old, long new))
{
long oldval;
unsigned long res;
smp_mb();
asm volatile("// atomic64_cmpxchg\n"
"1: ldxr %1, %2\n"
" cmp %1, %3\n"
" b.ne 2f\n"
" stxr %w0, %4, %2\n"
" cbnz %w0, 1b\n"
"2:"
: "=&r" (res), "=&r" (oldval), "+Q" (ptr->counter)
: "Ir" (old), "r" (new)
: "cc");
smp_mb();
return oldval;
}
__LL_SC_INLINE long
__LL_SC_PREFIX(atomic64_dec_if_positive(atomic64_t *v))
{
long result;
unsigned long tmp;
asm volatile("// atomic64_dec_if_positive\n"
"1: ldxr %0, %2\n"
" subs %0, %0, #1\n"
" b.mi 2f\n"
" stlxr %w1, %0, %2\n"
" cbnz %w1, 1b\n"
" dmb ish\n"
"2:"
: "=&r" (result), "=&r" (tmp), "+Q" (v->counter)
:
: "cc", "memory");
return result;
}
#endif /* __ASM_ATOMIC_LL_SC_H */
