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x86: implement atomic64_t on 32-bit
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Impact: new API

Implement the atomic64_t APIs on 32-bit as well. Will be used by
the performance counters code.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Ingo Molnar committed Dec 14, 2008
1 parent 92bf73e commit 9b194e8
Showing 1 changed file with 218 additions and 0 deletions.
218 changes: 218 additions & 0 deletions arch/x86/include/asm/atomic_32.h
Original file line number Diff line number Diff line change
Expand Up @@ -255,5 +255,223 @@ static inline int atomic_add_unless(atomic_t *v, int a, int u)
#define smp_mb__before_atomic_inc() barrier()
#define smp_mb__after_atomic_inc() barrier()

/* An 64bit atomic type */

typedef struct {
unsigned long long counter;
} atomic64_t;

#define ATOMIC64_INIT(val) { (val) }

/**
* atomic64_read - read atomic64 variable
* @v: pointer of type atomic64_t
*
* Atomically reads the value of @v.
* Doesn't imply a read memory barrier.
*/
#define __atomic64_read(ptr) ((ptr)->counter)

static inline unsigned long long
cmpxchg8b(unsigned long long *ptr, unsigned long long old, unsigned long long new)
{
asm volatile(

LOCK_PREFIX "cmpxchg8b (%[ptr])\n"

: "=A" (old)

: [ptr] "D" (ptr),
"A" (old),
"b" (ll_low(new)),
"c" (ll_high(new))

: "memory");

return old;
}

static inline unsigned long long
atomic64_cmpxchg(atomic64_t *ptr, unsigned long long old_val,
unsigned long long new_val)
{
return cmpxchg8b(&ptr->counter, old_val, new_val);
}

/**
* atomic64_set - set atomic64 variable
* @ptr: pointer to type atomic64_t
* @new_val: value to assign
*
* Atomically sets the value of @ptr to @new_val.
*/
static inline void atomic64_set(atomic64_t *ptr, unsigned long long new_val)
{
unsigned long long old_val;

do {
old_val = atomic_read(ptr);
} while (atomic64_cmpxchg(ptr, old_val, new_val) != old_val);
}

/**
* atomic64_read - read atomic64 variable
* @ptr: pointer to type atomic64_t
*
* Atomically reads the value of @ptr and returns it.
*/
static inline unsigned long long atomic64_read(atomic64_t *ptr)
{
unsigned long long curr_val;

do {
curr_val = __atomic64_read(ptr);
} while (atomic64_cmpxchg(ptr, curr_val, curr_val) != curr_val);

return curr_val;
}

/**
* atomic64_add_return - add and return
* @delta: integer value to add
* @ptr: pointer to type atomic64_t
*
* Atomically adds @delta to @ptr and returns @delta + *@ptr
*/
static inline unsigned long long
atomic64_add_return(unsigned long long delta, atomic64_t *ptr)
{
unsigned long long old_val, new_val;

do {
old_val = atomic_read(ptr);
new_val = old_val + delta;

} while (atomic64_cmpxchg(ptr, old_val, new_val) != old_val);

return new_val;
}

static inline long atomic64_sub_return(unsigned long long delta, atomic64_t *ptr)
{
return atomic64_add_return(-delta, ptr);
}

static inline long atomic64_inc_return(atomic64_t *ptr)
{
return atomic64_add_return(1, ptr);
}

static inline long atomic64_dec_return(atomic64_t *ptr)
{
return atomic64_sub_return(1, ptr);
}

/**
* atomic64_add - add integer to atomic64 variable
* @delta: integer value to add
* @ptr: pointer to type atomic64_t
*
* Atomically adds @delta to @ptr.
*/
static inline void atomic64_add(unsigned long long delta, atomic64_t *ptr)
{
atomic64_add_return(delta, ptr);
}

/**
* atomic64_sub - subtract the atomic64 variable
* @delta: integer value to subtract
* @ptr: pointer to type atomic64_t
*
* Atomically subtracts @delta from @ptr.
*/
static inline void atomic64_sub(unsigned long long delta, atomic64_t *ptr)
{
atomic64_add(-delta, ptr);
}

/**
* atomic64_sub_and_test - subtract value from variable and test result
* @delta: integer value to subtract
* @ptr: pointer to type atomic64_t
*
* Atomically subtracts @delta from @ptr and returns
* true if the result is zero, or false for all
* other cases.
*/
static inline int
atomic64_sub_and_test(unsigned long long delta, atomic64_t *ptr)
{
unsigned long long old_val = atomic64_sub_return(delta, ptr);

return old_val == 0;
}

/**
* atomic64_inc - increment atomic64 variable
* @ptr: pointer to type atomic64_t
*
* Atomically increments @ptr by 1.
*/
static inline void atomic64_inc(atomic64_t *ptr)
{
atomic64_add(1, ptr);
}

/**
* atomic64_dec - decrement atomic64 variable
* @ptr: pointer to type atomic64_t
*
* Atomically decrements @ptr by 1.
*/
static inline void atomic64_dec(atomic64_t *ptr)
{
atomic64_sub(1, ptr);
}

/**
* atomic64_dec_and_test - decrement and test
* @ptr: pointer to type atomic64_t
*
* Atomically decrements @ptr by 1 and
* returns true if the result is 0, or false for all other
* cases.
*/
static inline int atomic64_dec_and_test(atomic64_t *ptr)
{
return atomic64_sub_and_test(1, ptr);
}

/**
* atomic64_inc_and_test - increment and test
* @ptr: pointer to type atomic64_t
*
* Atomically increments @ptr by 1
* and returns true if the result is zero, or false for all
* other cases.
*/
static inline int atomic64_inc_and_test(atomic64_t *ptr)
{
return atomic64_sub_and_test(-1, ptr);
}

/**
* atomic64_add_negative - add and test if negative
* @delta: integer value to add
* @ptr: pointer to type atomic64_t
*
* Atomically adds @delta to @ptr and returns true
* if the result is negative, or false when
* result is greater than or equal to zero.
*/
static inline int
atomic64_add_negative(unsigned long long delta, atomic64_t *ptr)
{
long long old_val = atomic64_add_return(delta, ptr);

return old_val < 0;
}

#include <asm-generic/atomic.h>
#endif /* _ASM_X86_ATOMIC_32_H */

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