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/* $Id: rwsem.h,v 1.4 2001/04/26 02:36:36 davem Exp $
* rwsem.h: R/W semaphores implemented using CAS
*
* Written by David S. Miller (davem@redhat.com), 2001.
* Derived from asm-i386/rwsem.h
*/
#ifndef _SPARC64_RWSEM_H
#define _SPARC64_RWSEM_H
#ifndef _LINUX_RWSEM_H
#error please dont include asm/rwsem.h directly, use linux/rwsem.h instead
#endif
#ifdef __KERNEL__
#include <linux/list.h>
#include <linux/spinlock.h>
struct rwsem_waiter;
extern struct rw_semaphore *FASTCALL(rwsem_down_read_failed(struct rw_semaphore *sem));
extern struct rw_semaphore *FASTCALL(rwsem_down_write_failed(struct rw_semaphore *sem));
extern struct rw_semaphore *FASTCALL(rwsem_wake(struct rw_semaphore *));
struct rw_semaphore {
signed int count;
#define RWSEM_UNLOCKED_VALUE 0x00000000
#define RWSEM_ACTIVE_BIAS 0x00000001
#define RWSEM_ACTIVE_MASK 0x0000ffff
#define RWSEM_WAITING_BIAS 0xffff0000
#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
spinlock_t wait_lock;
struct list_head wait_list;
};
#define __RWSEM_INITIALIZER(name) \
{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) }
#define DECLARE_RWSEM(name) \
struct rw_semaphore name = __RWSEM_INITIALIZER(name)
static inline void init_rwsem(struct rw_semaphore *sem)
{
sem->count = RWSEM_UNLOCKED_VALUE;
spin_lock_init(&sem->wait_lock);
INIT_LIST_HEAD(&sem->wait_list);
}
static inline void __down_read(struct rw_semaphore *sem)
{
__asm__ __volatile__(
"! beginning __down_read\n"
"1:\tlduw [%0], %%g5\n\t"
"add %%g5, 1, %%g7\n\t"
"cas [%0], %%g5, %%g7\n\t"
"cmp %%g5, %%g7\n\t"
"bne,pn %%icc, 1b\n\t"
" add %%g7, 1, %%g7\n\t"
"cmp %%g7, 0\n\t"
"bl,pn %%icc, 3f\n\t"
" membar #StoreStore\n"
"2:\n\t"
".subsection 2\n"
"3:\tmov %0, %%g5\n\t"
"save %%sp, -160, %%sp\n\t"
"mov %%g1, %%l1\n\t"
"mov %%g2, %%l2\n\t"
"mov %%g3, %%l3\n\t"
"call %1\n\t"
" mov %%g5, %%o0\n\t"
"mov %%l1, %%g1\n\t"
"mov %%l2, %%g2\n\t"
"ba,pt %%xcc, 2b\n\t"
" restore %%l3, %%g0, %%g3\n\t"
".previous\n\t"
"! ending __down_read"
: : "r" (sem), "i" (rwsem_down_read_failed)
: "g5", "g7", "memory", "cc");
}
static inline void __down_write(struct rw_semaphore *sem)
{
__asm__ __volatile__(
"! beginning __down_write\n\t"
"sethi %%hi(%2), %%g1\n\t"
"or %%g1, %%lo(%2), %%g1\n"
"1:\tlduw [%0], %%g5\n\t"
"add %%g5, %%g1, %%g7\n\t"
"cas [%0], %%g5, %%g7\n\t"
"cmp %%g5, %%g7\n\t"
"bne,pn %%icc, 1b\n\t"
" cmp %%g7, 0\n\t"
"bne,pn %%icc, 3f\n\t"
" membar #StoreStore\n"
"2:\n\t"
".subsection 2\n"
"3:\tmov %0, %%g5\n\t"
"save %%sp, -160, %%sp\n\t"
"mov %%g2, %%l2\n\t"
"mov %%g3, %%l3\n\t"
"call %1\n\t"
" mov %%g5, %%o0\n\t"
"mov %%l2, %%g2\n\t"
"ba,pt %%xcc, 2b\n\t"
" restore %%l3, %%g0, %%g3\n\t"
".previous\n\t"
"! ending __down_write"
: : "r" (sem), "i" (rwsem_down_write_failed),
"i" (RWSEM_ACTIVE_WRITE_BIAS)
: "g1", "g5", "g7", "memory", "cc");
}
static inline void __up_read(struct rw_semaphore *sem)
{
__asm__ __volatile__(
"! beginning __up_read\n\t"
"1:\tlduw [%0], %%g5\n\t"
"sub %%g5, 1, %%g7\n\t"
"cas [%0], %%g5, %%g7\n\t"
"cmp %%g5, %%g7\n\t"
"bne,pn %%icc, 1b\n\t"
" cmp %%g7, 0\n\t"
"bl,pn %%icc, 3f\n\t"
" membar #StoreStore\n"
"2:\n\t"
".subsection 2\n"
"3:\tsethi %%hi(%2), %%g1\n\t"
"sub %%g7, 1, %%g7\n\t"
"or %%g1, %%lo(%2), %%g1\n\t"
"andcc %%g7, %%g1, %%g0\n\t"
"bne,pn %%icc, 2b\n\t"
" mov %0, %%g5\n\t"
"save %%sp, -160, %%sp\n\t"
"mov %%g2, %%l2\n\t"
"mov %%g3, %%l3\n\t"
"call %1\n\t"
" mov %%g5, %%o0\n\t"
"mov %%l2, %%g2\n\t"
"ba,pt %%xcc, 2b\n\t"
" restore %%l3, %%g0, %%g3\n\t"
".previous\n\t"
"! ending __up_read"
: : "r" (sem), "i" (rwsem_wake),
"i" (RWSEM_ACTIVE_MASK)
: "g1", "g5", "g7", "memory", "cc");
}
static inline void __up_write(struct rw_semaphore *sem)
{
__asm__ __volatile__(
"! beginning __up_write\n\t"
"sethi %%hi(%2), %%g1\n\t"
"or %%g1, %%lo(%2), %%g1\n"
"1:\tlduw [%0], %%g5\n\t"
"sub %%g5, %%g1, %%g7\n\t"
"cas [%0], %%g5, %%g7\n\t"
"cmp %%g5, %%g7\n\t"
"bne,pn %%icc, 1b\n\t"
" sub %%g7, %%g1, %%g7\n\t"
"cmp %%g7, 0\n\t"
"bl,pn %%icc, 3f\n\t"
" membar #StoreStore\n"
"2:\n\t"
".subsection 2\n"
"3:\tmov %0, %%g5\n\t"
"save %%sp, -160, %%sp\n\t"
"mov %%g2, %%l2\n\t"
"mov %%g3, %%l3\n\t"
"call %1\n\t"
" mov %%g5, %%o0\n\t"
"mov %%l2, %%g2\n\t"
"ba,pt %%xcc, 2b\n\t"
" restore %%l3, %%g0, %%g3\n\t"
".previous\n\t"
"! ending __up_write"
: : "r" (sem), "i" (rwsem_wake),
"i" (RWSEM_ACTIVE_WRITE_BIAS)
: "g1", "g5", "g7", "memory", "cc");
}
static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
{
int tmp = delta;
__asm__ __volatile__(
"1:\tlduw [%2], %%g5\n\t"
"add %%g5, %1, %%g7\n\t"
"cas [%2], %%g5, %%g7\n\t"
"cmp %%g5, %%g7\n\t"
"bne,pn %%icc, 1b\n\t"
" nop\n\t"
"mov %%g7, %0\n\t"
: "=&r" (tmp)
: "0" (tmp), "r" (sem)
: "g5", "g7", "memory");
return tmp + delta;
}
#define rwsem_atomic_add rwsem_atomic_update
static inline __u16 rwsem_cmpxchgw(struct rw_semaphore *sem, __u16 __old, __u16 __new)
{
u32 old = (sem->count & 0xffff0000) | (u32) __old;
u32 new = (old & 0xffff0000) | (u32) __new;
u32 prev;
again:
__asm__ __volatile__("cas [%2], %3, %0\n\t"
"membar #StoreStore | #StoreLoad"
: "=&r" (prev)
: "0" (new), "r" (sem), "r" (old)
: "memory");
/* To give the same semantics as x86 cmpxchgw, keep trying
* if only the upper 16-bits changed.
*/
if (prev != old &&
((prev & 0xffff) == (old & 0xffff)))
goto again;
return prev & 0xffff;
}
static inline signed long rwsem_cmpxchg(struct rw_semaphore *sem, signed long old, signed long new)
{
return cmpxchg(&sem->count,old,new);
}
#endif /* __KERNEL__ */
#endif /* _SPARC64_RWSEM_H */
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