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#ifndef __ASM_SPINLOCK_H
#define __ASM_SPINLOCK_H
#include <xen/config.h>
#include <xen/lib.h>
#include <asm/atomic.h>
typedef struct {
volatile s16 lock;
} raw_spinlock_t;
#define _RAW_SPIN_LOCK_UNLOCKED /*(raw_spinlock_t)*/ { 1 }
#define _raw_spin_is_locked(x) ((x)->lock <= 0)
static always_inline void _raw_spin_unlock(raw_spinlock_t *lock)
{
ASSERT(_raw_spin_is_locked(lock));
asm volatile (
"movw $1,%0"
: "=m" (lock->lock) : : "memory" );
}
static always_inline int _raw_spin_trylock(raw_spinlock_t *lock)
{
s16 oldval;
asm volatile (
"xchgw %w0,%1"
:"=r" (oldval), "=m" (lock->lock)
:"0" ((s16)0) : "memory" );
return (oldval > 0);
}
typedef struct {
volatile int lock;
} raw_rwlock_t;
#define RW_WRITE_BIAS 0x7fffffff
#define _RAW_RW_LOCK_UNLOCKED /*(raw_rwlock_t)*/ { 0 }
static always_inline int _raw_read_trylock(raw_rwlock_t *rw)
{
int acquired;
asm volatile (
" lock; decl %0 \n"
" jns 2f \n"
#ifdef __clang__ /* clang's builtin assember can't do .subsection */
"1: .pushsection .fixup,\"ax\"\n"
#else
"1: .subsection 1 \n"
#endif
"2: lock; incl %0 \n"
" decl %1 \n"
" jmp 1b \n"
#ifdef __clang__
" .popsection \n"
#else
" .subsection 0 \n"
#endif
: "=m" (rw->lock), "=r" (acquired) : "1" (1) : "memory" );
return acquired;
}
static always_inline int _raw_write_trylock(raw_rwlock_t *rw)
{
return (cmpxchg(&rw->lock, 0, RW_WRITE_BIAS) == 0);
}
static always_inline void _raw_read_unlock(raw_rwlock_t *rw)
{
asm volatile (
"lock ; incl %0"
: "=m" ((rw)->lock) : : "memory" );
}
static always_inline void _raw_write_unlock(raw_rwlock_t *rw)
{
asm volatile (
"lock ; subl %1,%0"
: "=m" ((rw)->lock) : "i" (RW_WRITE_BIAS) : "memory" );
}
#define _raw_rw_is_locked(x) ((x)->lock != 0)
#define _raw_rw_is_write_locked(x) ((x)->lock > 0)
#endif /* __ASM_SPINLOCK_H */
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