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linux_dsm_epyc7002/arch/arm/include/asm/atomic.h
Will Deacon 4fd75911f6 ARM: 7687/1: atomics: don't use exclusives for atomic64 read/set with LPAE 
To ease page table updates with 64-bit descriptors, CPUs implementing
LPAE are required to implement ldrd/strd as atomic operations.

This patch uses these accessors instead of the exclusive variants when
performing atomic64_{read,set} on LPAE systems.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-04-03 17:00:00 +01:00

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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 <linux/irqflags.h>
#include <asm/barrier.h>
#include <asm/cmpxchg.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) (*(volatile int *)&(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, [%3]\n"
" add %0, %0, %4\n"
" strex %1, %0, [%3]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp), "+Qo" (v->counter)
: "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, [%3]\n"
" add %0, %0, %4\n"
" strex %1, %0, [%3]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp), "+Qo" (v->counter)
: "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, [%3]\n"
" sub %0, %0, %4\n"
" strex %1, %0, [%3]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp), "+Qo" (v->counter)
: "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, [%3]\n"
" sub %0, %0, %4\n"
" strex %1, %0, [%3]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp), "+Qo" (v->counter)
: "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, [%3]\n"
"mov %0, #0\n"
"teq %1, %4\n"
"strexeq %0, %5, [%3]\n"
: "=&r" (res), "=&r" (oldval), "+Qo" (ptr->counter)
: "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, [%3]\n"
" bic %0, %0, %4\n"
" strex %1, %0, [%3]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (tmp), "=&r" (tmp2), "+Qo" (*addr)
: "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;
}
#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) }
#ifdef CONFIG_ARM_LPAE
static inline u64 atomic64_read(const atomic64_t *v)
{
u64 result;
__asm__ __volatile__("@ atomic64_read\n"
" ldrd %0, %H0, [%1]"
: "=&r" (result)
: "r" (&v->counter), "Qo" (v->counter)
);
return result;
}
static inline void atomic64_set(atomic64_t *v, u64 i)
{
__asm__ __volatile__("@ atomic64_set\n"
" strd %2, %H2, [%1]"
: "=Qo" (v->counter)
: "r" (&v->counter), "r" (i)
);
}
#else
static inline u64 atomic64_read(const atomic64_t *v)
{
u64 result;
__asm__ __volatile__("@ atomic64_read\n"
" ldrexd %0, %H0, [%1]"
: "=&r" (result)
: "r" (&v->counter), "Qo" (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, [%2]\n"
" strexd %0, %3, %H3, [%2]\n"
" teq %0, #0\n"
" bne 1b"
: "=&r" (tmp), "=Qo" (v->counter)
: "r" (&v->counter), "r" (i)
: "cc");
}
#endif
static inline void atomic64_add(u64 i, atomic64_t *v)
{
u64 result;
unsigned long tmp;
__asm__ __volatile__("@ atomic64_add\n"
"1: ldrexd %0, %H0, [%3]\n"
" adds %0, %0, %4\n"
" adc %H0, %H0, %H4\n"
" strexd %1, %0, %H0, [%3]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp), "+Qo" (v->counter)
: "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, [%3]\n"
" adds %0, %0, %4\n"
" adc %H0, %H0, %H4\n"
" strexd %1, %0, %H0, [%3]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp), "+Qo" (v->counter)
: "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, [%3]\n"
" subs %0, %0, %4\n"
" sbc %H0, %H0, %H4\n"
" strexd %1, %0, %H0, [%3]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp), "+Qo" (v->counter)
: "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, [%3]\n"
" subs %0, %0, %4\n"
" sbc %H0, %H0, %H4\n"
" strexd %1, %0, %H0, [%3]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp), "+Qo" (v->counter)
: "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, [%3]\n"
"mov %0, #0\n"
"teq %1, %4\n"
"teqeq %H1, %H4\n"
"strexdeq %0, %5, %H5, [%3]"
: "=&r" (res), "=&r" (oldval), "+Qo" (ptr->counter)
: "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, [%3]\n"
" strexd %1, %4, %H4, [%3]\n"
" teq %1, #0\n"
" bne 1b"
: "=&r" (result), "=&r" (tmp), "+Qo" (ptr->counter)
: "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, [%3]\n"
" subs %0, %0, #1\n"
" sbc %H0, %H0, #0\n"
" teq %H0, #0\n"
" bmi 2f\n"
" strexd %1, %0, %H0, [%3]\n"
" teq %1, #0\n"
" bne 1b\n"
"2:"
: "=&r" (result), "=&r" (tmp), "+Qo" (v->counter)
: "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, [%4]\n"
" teq %0, %5\n"
" teqeq %H0, %H5\n"
" moveq %1, #0\n"
" beq 2f\n"
" adds %0, %0, %6\n"
" adc %H0, %H0, %H6\n"
" strexd %2, %0, %H0, [%4]\n"
" teq %2, #0\n"
" bne 1b\n"
"2:"
: "=&r" (val), "+r" (ret), "=&r" (tmp), "+Qo" (v->counter)
: "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)
#endif /* !CONFIG_GENERIC_ATOMIC64 */
#endif
#endif
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