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linux/arch/arm/include/asm/atomic.h
Will Deacon 24b44a66fa ARM: 5889/1: Add atomic64 routines for ARMv6k and above. 
In preparation for perf-events support, ARM needs to support atomic64_t
operations. v6k and above support the ldrexd and strexd instructions to
do just that.

This patch adds atomic64 support to the ARM architecture. v6k and above
make use of new instructions whilst older cores fall back on the generic
solution using spinlocks. If and when v7-M cores are supported by Linux,
they will need to fall back on the spinlock implementation too.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-02-15 21:39:50 +00:00

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/*
* arch/arm/include/asm/atomic.h
*
* Copyright (C) 1996 Russell King.
* Copyright (C) 2002 Deep Blue Solutions 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.
*/
#ifndef __ASM_ARM_ATOMIC_H
#define __ASM_ARM_ATOMIC_H
#include <linux/compiler.h>
#include <linux/types.h>
#include <asm/system.h>
#define ATOMIC_INIT(i) { (i) }
#ifdef __KERNEL__
/*
* On ARM, ordinary assignment (str instruction) doesn't clear the local
* strex/ldrex monitor on some implementations. The reason we can use it for
* atomic_set() is the clrex or dummy strex done on every exception return.
*/
#define atomic_read(v) ((v)->counter)
#define atomic_set(v,i) (((v)->counter) = (i))
#if __LINUX_ARM_ARCH__ >= 6
/*
* ARMv6 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.
*/
static inline void atomic_add(int i, atomic_t *v)
{
unsigned long tmp;
int result;
__asm__ __volatile__("@ atomic_add\n"
"1: ldrex %0, [%2]\n"
" add %0, %0, %3\n"
" strex %1, %0, [%2]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp)
: "r" (&v->counter), "Ir" (i)
: "cc");
}
static inline int atomic_add_return(int i, atomic_t *v)
{
unsigned long tmp;
int result;
smp_mb();
__asm__ __volatile__("@ atomic_add_return\n"
"1: ldrex %0, [%2]\n"
" add %0, %0, %3\n"
" strex %1, %0, [%2]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp)
: "r" (&v->counter), "Ir" (i)
: "cc");
smp_mb();
return result;
}
static inline void atomic_sub(int i, atomic_t *v)
{
unsigned long tmp;
int result;
__asm__ __volatile__("@ atomic_sub\n"
"1: ldrex %0, [%2]\n"
" sub %0, %0, %3\n"
" strex %1, %0, [%2]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp)
: "r" (&v->counter), "Ir" (i)
: "cc");
}
static inline int atomic_sub_return(int i, atomic_t *v)
{
unsigned long tmp;
int result;
smp_mb();
__asm__ __volatile__("@ atomic_sub_return\n"
"1: ldrex %0, [%2]\n"
" sub %0, %0, %3\n"
" strex %1, %0, [%2]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp)
: "r" (&v->counter), "Ir" (i)
: "cc");
smp_mb();
return result;
}
static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new)
{
unsigned long oldval, res;
smp_mb();
do {
__asm__ __volatile__("@ atomic_cmpxchg\n"
"ldrex %1, [%2]\n"
"mov %0, #0\n"
"teq %1, %3\n"
"strexeq %0, %4, [%2]\n"
: "=&r" (res), "=&r" (oldval)
: "r" (&ptr->counter), "Ir" (old), "r" (new)
: "cc");
} while (res);
smp_mb();
return oldval;
}
static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
{
unsigned long tmp, tmp2;
__asm__ __volatile__("@ atomic_clear_mask\n"
"1: ldrex %0, [%2]\n"
" bic %0, %0, %3\n"
" strex %1, %0, [%2]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (tmp), "=&r" (tmp2)
: "r" (addr), "Ir" (mask)
: "cc");
}
#else /* ARM_ARCH_6 */
#ifdef CONFIG_SMP
#error SMP not supported on pre-ARMv6 CPUs
#endif
static inline int atomic_add_return(int i, atomic_t *v)
{
unsigned long flags;
int val;
raw_local_irq_save(flags);
val = v->counter;
v->counter = val += i;
raw_local_irq_restore(flags);
return val;
}
#define atomic_add(i, v) (void) atomic_add_return(i, v)
static inline int atomic_sub_return(int i, atomic_t *v)
{
unsigned long flags;
int val;
raw_local_irq_save(flags);
val = v->counter;
v->counter = val -= i;
raw_local_irq_restore(flags);
return val;
}
#define atomic_sub(i, v) (void) atomic_sub_return(i, v)
static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
{
int ret;
unsigned long flags;
raw_local_irq_save(flags);
ret = v->counter;
if (likely(ret == old))
v->counter = new;
raw_local_irq_restore(flags);
return ret;
}
static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
{
unsigned long flags;
raw_local_irq_save(flags);
*addr &= ~mask;
raw_local_irq_restore(flags);
}
#endif /* __LINUX_ARM_ARCH__ */
#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
static inline int atomic_add_unless(atomic_t *v, int a, int u)
{
int c, old;
c = atomic_read(v);
while (c != u && (old = atomic_cmpxchg((v), c, c + a)) != c)
c = old;
return c != u;
}
#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
#define atomic_inc(v) atomic_add(1, v)
#define atomic_dec(v) atomic_sub(1, v)
#define atomic_inc_and_test(v) (atomic_add_return(1, v) == 0)
#define atomic_dec_and_test(v) (atomic_sub_return(1, v) == 0)
#define atomic_inc_return(v) (atomic_add_return(1, v))
#define atomic_dec_return(v) (atomic_sub_return(1, v))
#define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
#define atomic_add_negative(i,v) (atomic_add_return(i, v) < 0)
#define smp_mb__before_atomic_dec() smp_mb()
#define smp_mb__after_atomic_dec() smp_mb()
#define smp_mb__before_atomic_inc() smp_mb()
#define smp_mb__after_atomic_inc() smp_mb()
#ifndef CONFIG_GENERIC_ATOMIC64
typedef struct {
u64 __aligned(8) counter;
} atomic64_t;
#define ATOMIC64_INIT(i) { (i) }
static inline u64 atomic64_read(atomic64_t *v)
{
u64 result;
__asm__ __volatile__("@ atomic64_read\n"
" ldrexd %0, %H0, [%1]"
: "=&r" (result)
: "r" (&v->counter)
);
return result;
}
static inline void atomic64_set(atomic64_t *v, u64 i)
{
u64 tmp;
__asm__ __volatile__("@ atomic64_set\n"
"1: ldrexd %0, %H0, [%1]\n"
" strexd %0, %2, %H2, [%1]\n"
" teq %0, #0\n"
" bne 1b"
: "=&r" (tmp)
: "r" (&v->counter), "r" (i)
: "cc");
}
static inline void atomic64_add(u64 i, atomic64_t *v)
{
u64 result;
unsigned long tmp;
__asm__ __volatile__("@ atomic64_add\n"
"1: ldrexd %0, %H0, [%2]\n"
" adds %0, %0, %3\n"
" adc %H0, %H0, %H3\n"
" strexd %1, %0, %H0, [%2]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp)
: "r" (&v->counter), "r" (i)
: "cc");
}
static inline u64 atomic64_add_return(u64 i, atomic64_t *v)
{
u64 result;
unsigned long tmp;
smp_mb();
__asm__ __volatile__("@ atomic64_add_return\n"
"1: ldrexd %0, %H0, [%2]\n"
" adds %0, %0, %3\n"
" adc %H0, %H0, %H3\n"
" strexd %1, %0, %H0, [%2]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp)
: "r" (&v->counter), "r" (i)
: "cc");
smp_mb();
return result;
}
static inline void atomic64_sub(u64 i, atomic64_t *v)
{
u64 result;
unsigned long tmp;
__asm__ __volatile__("@ atomic64_sub\n"
"1: ldrexd %0, %H0, [%2]\n"
" subs %0, %0, %3\n"
" sbc %H0, %H0, %H3\n"
" strexd %1, %0, %H0, [%2]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp)
: "r" (&v->counter), "r" (i)
: "cc");
}
static inline u64 atomic64_sub_return(u64 i, atomic64_t *v)
{
u64 result;
unsigned long tmp;
smp_mb();
__asm__ __volatile__("@ atomic64_sub_return\n"
"1: ldrexd %0, %H0, [%2]\n"
" subs %0, %0, %3\n"
" sbc %H0, %H0, %H3\n"
" strexd %1, %0, %H0, [%2]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp)
: "r" (&v->counter), "r" (i)
: "cc");
smp_mb();
return result;
}
static inline u64 atomic64_cmpxchg(atomic64_t *ptr, u64 old, u64 new)
{
u64 oldval;
unsigned long res;
smp_mb();
do {
__asm__ __volatile__("@ atomic64_cmpxchg\n"
"ldrexd %1, %H1, [%2]\n"
"mov %0, #0\n"
"teq %1, %3\n"
"teqeq %H1, %H3\n"
"strexdeq %0, %4, %H4, [%2]"
: "=&r" (res), "=&r" (oldval)
: "r" (&ptr->counter), "r" (old), "r" (new)
: "cc");
} while (res);
smp_mb();
return oldval;
}
static inline u64 atomic64_xchg(atomic64_t *ptr, u64 new)
{
u64 result;
unsigned long tmp;
smp_mb();
__asm__ __volatile__("@ atomic64_xchg\n"
"1: ldrexd %0, %H0, [%2]\n"
" strexd %1, %3, %H3, [%2]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp)
: "r" (&ptr->counter), "r" (new)
: "cc");
smp_mb();
return result;
}
static inline u64 atomic64_dec_if_positive(atomic64_t *v)
{
u64 result;
unsigned long tmp;
smp_mb();
__asm__ __volatile__("@ atomic64_dec_if_positive\n"
"1: ldrexd %0, %H0, [%2]\n"
" subs %0, %0, #1\n"
" sbc %H0, %H0, #0\n"
" teq %H0, #0\n"
" bmi 2f\n"
" strexd %1, %0, %H0, [%2]\n"
" teq %1, #0\n"
" bne 1b\n"
"2:"
: "=&r" (result), "=&r" (tmp)
: "r" (&v->counter)
: "cc");
smp_mb();
return result;
}
static inline int atomic64_add_unless(atomic64_t *v, u64 a, u64 u)
{
u64 val;
unsigned long tmp;
int ret = 1;
smp_mb();
__asm__ __volatile__("@ atomic64_add_unless\n"
"1: ldrexd %0, %H0, [%3]\n"
" teq %0, %4\n"
" teqeq %H0, %H4\n"
" moveq %1, #0\n"
" beq 2f\n"
" adds %0, %0, %5\n"
" adc %H0, %H0, %H5\n"
" strexd %2, %0, %H0, [%3]\n"
" teq %2, #0\n"
" bne 1b\n"
"2:"
: "=&r" (val), "=&r" (ret), "=&r" (tmp)
: "r" (&v->counter), "r" (u), "r" (a)
: "cc");
if (ret)
smp_mb();
return ret;
}
#define atomic64_add_negative(a, v) (atomic64_add_return((a), (v)) < 0)
#define atomic64_inc(v) atomic64_add(1LL, (v))
#define atomic64_inc_return(v) atomic64_add_return(1LL, (v))
#define atomic64_inc_and_test(v) (atomic64_inc_return(v) == 0)
#define atomic64_sub_and_test(a, v) (atomic64_sub_return((a), (v)) == 0)
#define atomic64_dec(v) atomic64_sub(1LL, (v))
#define atomic64_dec_return(v) atomic64_sub_return(1LL, (v))
#define atomic64_dec_and_test(v) (atomic64_dec_return((v)) == 0)
#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1LL, 0LL)
#else /* !CONFIG_GENERIC_ATOMIC64 */
#include <asm-generic/atomic64.h>
#endif
#include <asm-generic/atomic-long.h>
#endif
#endif
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