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#include <linux/compiler.h>
#include <linux/module.h>
#include <linux/types.h>
#include <asm/processor.h>
#include <asm/cmpxchg.h>
#include <asm/atomic.h>
static noinline u64 cmpxchg8b(u64 *ptr, u64 old, u64 new)
{
u32 low = new;
u32 high = new >> 32;
asm volatile(
LOCK_PREFIX "cmpxchg8b %1\n"
: "+A" (old), "+m" (*ptr)
: "b" (low), "c" (high)
);
return old;
}
u64 atomic64_cmpxchg(atomic64_t *ptr, u64 old_val, u64 new_val)
{
return cmpxchg8b(&ptr->counter, old_val, new_val);
}
EXPORT_SYMBOL(atomic64_cmpxchg);
/**
* atomic64_xchg - xchg atomic64 variable
* @ptr: pointer to type atomic64_t
* @new_val: value to assign
*
* Atomically xchgs the value of @ptr to @new_val and returns
* the old value.
*/
u64 atomic64_xchg(atomic64_t *ptr, u64 new_val)
{
/*
* Try first with a (possibly incorrect) assumption about
* what we have there. We'll do two loops most likely,
* but we'll get an ownership MESI transaction straight away
* instead of a read transaction followed by a
* flush-for-ownership transaction:
*/
u64 old_val, real_val = 0;
do {
old_val = real_val;
real_val = atomic64_cmpxchg(ptr, old_val, new_val);
} while (real_val != old_val);
return old_val;
}
EXPORT_SYMBOL(atomic64_xchg);
/**
* 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.
*/
void atomic64_set(atomic64_t *ptr, u64 new_val)
{
atomic64_xchg(ptr, new_val);
}
EXPORT_SYMBOL(atomic64_read);
/**
* atomic64_read - read atomic64 variable
* @ptr: pointer to type atomic64_t
*
* Atomically reads the value of @ptr and returns it.
*/
u64 atomic64_read(atomic64_t *ptr)
{
u64 res;
asm volatile(
"mov %%ebx, %%eax\n\t"
"mov %%ecx, %%edx\n\t"
LOCK_PREFIX "cmpxchg8b %1\n"
: "+A" (res)
: "m" (*ptr)
);
return res;
}
EXPORT_SYMBOL(atomic64_read);
/**
* 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
*/
noinline u64 atomic64_add_return(u64 delta, atomic64_t *ptr)
{
/*
* Try first with a (possibly incorrect) assumption about
* what we have there. We'll do two loops most likely,
* but we'll get an ownership MESI transaction straight away
* instead of a read transaction followed by a
* flush-for-ownership transaction:
*/
u64 old_val, new_val, real_val = 0;
do {
old_val = real_val;
new_val = old_val + delta;
real_val = atomic64_cmpxchg(ptr, old_val, new_val);
} while (real_val != old_val);
return new_val;
}
EXPORT_SYMBOL(atomic64_add_return);
u64 atomic64_sub_return(u64 delta, atomic64_t *ptr)
{
return atomic64_add_return(-delta, ptr);
}
EXPORT_SYMBOL(atomic64_sub_return);
u64 atomic64_inc_return(atomic64_t *ptr)
{
return atomic64_add_return(1, ptr);
}
EXPORT_SYMBOL(atomic64_inc_return);
u64 atomic64_dec_return(atomic64_t *ptr)
{
return atomic64_sub_return(1, ptr);
}
EXPORT_SYMBOL(atomic64_dec_return);
/**
* atomic64_add - add integer to atomic64 variable
* @delta: integer value to add
* @ptr: pointer to type atomic64_t
*
* Atomically adds @delta to @ptr.
*/
void atomic64_add(u64 delta, atomic64_t *ptr)
{
atomic64_add_return(delta, ptr);
}
EXPORT_SYMBOL(atomic64_add);
/**
* atomic64_sub - subtract the atomic64 variable
* @delta: integer value to subtract
* @ptr: pointer to type atomic64_t
*
* Atomically subtracts @delta from @ptr.
*/
void atomic64_sub(u64 delta, atomic64_t *ptr)
{
atomic64_add(-delta, ptr);
}
EXPORT_SYMBOL(atomic64_sub);
/**
* 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.
*/
int atomic64_sub_and_test(u64 delta, atomic64_t *ptr)
{
u64 new_val = atomic64_sub_return(delta, ptr);
return new_val == 0;
}
EXPORT_SYMBOL(atomic64_sub_and_test);
/**
* atomic64_inc - increment atomic64 variable
* @ptr: pointer to type atomic64_t
*
* Atomically increments @ptr by 1.
*/
void atomic64_inc(atomic64_t *ptr)
{
atomic64_add(1, ptr);
}
EXPORT_SYMBOL(atomic64_inc);
/**
* atomic64_dec - decrement atomic64 variable
* @ptr: pointer to type atomic64_t
*
* Atomically decrements @ptr by 1.
*/
void atomic64_dec(atomic64_t *ptr)
{
atomic64_sub(1, ptr);
}
EXPORT_SYMBOL(atomic64_dec);
/**
* 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.
*/
int atomic64_dec_and_test(atomic64_t *ptr)
{
return atomic64_sub_and_test(1, ptr);
}
EXPORT_SYMBOL(atomic64_dec_and_test);
/**
* 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.
*/
int atomic64_inc_and_test(atomic64_t *ptr)
{
return atomic64_sub_and_test(-1, ptr);
}
EXPORT_SYMBOL(atomic64_inc_and_test);
/**
* 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.
*/
int atomic64_add_negative(u64 delta, atomic64_t *ptr)
{
s64 new_val = atomic64_add_return(delta, ptr);
return new_val < 0;
}
EXPORT_SYMBOL(atomic64_add_negative);
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