blob: 59aa966dc2127c61be2e3bbe443516a54e70c725 [file] [log] [blame]
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_LOCAL_H
#define _ASM_X86_LOCAL_H
#include <linux/percpu.h>
#include <linux/atomic.h>
#include <asm/asm.h>
typedef struct {
atomic_long_t a;
} local_t;
#define LOCAL_INIT(i) { ATOMIC_LONG_INIT(i) }
#define local_read(l) atomic_long_read(&(l)->a)
#define local_set(l, i) atomic_long_set(&(l)->a, (i))
static inline void local_inc(local_t *l)
{
asm volatile(_ASM_INC "%0"
: "+m" (l->a.counter));
}
static inline void local_dec(local_t *l)
{
asm volatile(_ASM_DEC "%0"
: "+m" (l->a.counter));
}
static inline void local_add(long i, local_t *l)
{
asm volatile(_ASM_ADD "%1,%0"
: "+m" (l->a.counter)
: "ir" (i));
}
static inline void local_sub(long i, local_t *l)
{
asm volatile(_ASM_SUB "%1,%0"
: "+m" (l->a.counter)
: "ir" (i));
}
/**
* local_sub_and_test - subtract value from variable and test result
* @i: integer value to subtract
* @l: pointer to type local_t
*
* Atomically subtracts @i from @l and returns
* true if the result is zero, or false for all
* other cases.
*/
static inline bool local_sub_and_test(long i, local_t *l)
{
return GEN_BINARY_RMWcc(_ASM_SUB, l->a.counter, e, "er", i);
}
/**
* local_dec_and_test - decrement and test
* @l: pointer to type local_t
*
* Atomically decrements @l by 1 and
* returns true if the result is 0, or false for all other
* cases.
*/
static inline bool local_dec_and_test(local_t *l)
{
return GEN_UNARY_RMWcc(_ASM_DEC, l->a.counter, e);
}
/**
* local_inc_and_test - increment and test
* @l: pointer to type local_t
*
* Atomically increments @l by 1
* and returns true if the result is zero, or false for all
* other cases.
*/
static inline bool local_inc_and_test(local_t *l)
{
return GEN_UNARY_RMWcc(_ASM_INC, l->a.counter, e);
}
/**
* local_add_negative - add and test if negative
* @i: integer value to add
* @l: pointer to type local_t
*
* Atomically adds @i to @l and returns true
* if the result is negative, or false when
* result is greater than or equal to zero.
*/
static inline bool local_add_negative(long i, local_t *l)
{
return GEN_BINARY_RMWcc(_ASM_ADD, l->a.counter, s, "er", i);
}
/**
* local_add_return - add and return
* @i: integer value to add
* @l: pointer to type local_t
*
* Atomically adds @i to @l and returns @i + @l
*/
static inline long local_add_return(long i, local_t *l)
{
long __i = i;
asm volatile(_ASM_XADD "%0, %1;"
: "+r" (i), "+m" (l->a.counter)
: : "memory");
return i + __i;
}
static inline long local_sub_return(long i, local_t *l)
{
return local_add_return(-i, l);
}
#define local_inc_return(l) (local_add_return(1, l))
#define local_dec_return(l) (local_sub_return(1, l))
static inline long local_cmpxchg(local_t *l, long old, long new)
{
return cmpxchg_local(&l->a.counter, old, new);
}
static inline bool local_try_cmpxchg(local_t *l, long *old, long new)
{
return try_cmpxchg_local(&l->a.counter,
(typeof(l->a.counter) *) old, new);
}
/*
* Implement local_xchg using CMPXCHG instruction without the LOCK prefix.
* XCHG is expensive due to the implied LOCK prefix. The processor
* cannot prefetch cachelines if XCHG is used.
*/
static __always_inline long
local_xchg(local_t *l, long n)
{
long c = local_read(l);
do { } while (!local_try_cmpxchg(l, &c, n));
return c;
}
/**
* local_add_unless - add unless the number is already a given value
* @l: pointer of type local_t
* @a: the amount to add to l...
* @u: ...unless l is equal to u.
*
* Atomically adds @a to @l, if @v was not already @u.
* Returns true if the addition was done.
*/
static __always_inline bool
local_add_unless(local_t *l, long a, long u)
{
long c = local_read(l);
do {
if (unlikely(c == u))
return false;
} while (!local_try_cmpxchg(l, &c, c + a));
return true;
}
#define local_inc_not_zero(l) local_add_unless((l), 1, 0)
/* On x86_32, these are no better than the atomic variants.
* On x86-64 these are better than the atomic variants on SMP kernels
* because they dont use a lock prefix.
*/
#define __local_inc(l) local_inc(l)
#define __local_dec(l) local_dec(l)
#define __local_add(i, l) local_add((i), (l))
#define __local_sub(i, l) local_sub((i), (l))
#endif /* _ASM_X86_LOCAL_H */