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Linux/include/asm-sparc64/rwsem.h

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  1 /* $Id: rwsem.h,v 1.5 2001/11/18 00:12:56 davem Exp $
  2  * rwsem.h: R/W semaphores implemented using CAS
  3  *
  4  * Written by David S. Miller (davem@redhat.com), 2001.
  5  * Derived from asm-i386/rwsem.h
  6  */
  7 #ifndef _SPARC64_RWSEM_H
  8 #define _SPARC64_RWSEM_H
  9 
 10 #ifndef _LINUX_RWSEM_H
 11 #error please dont include asm/rwsem.h directly, use linux/rwsem.h instead
 12 #endif
 13 
 14 #ifdef __KERNEL__
 15 
 16 #include <linux/list.h>
 17 #include <linux/spinlock.h>
 18 
 19 struct rwsem_waiter;
 20 
 21 extern struct rw_semaphore *FASTCALL(rwsem_down_read_failed(struct rw_semaphore *sem));
 22 extern struct rw_semaphore *FASTCALL(rwsem_down_write_failed(struct rw_semaphore *sem));
 23 extern struct rw_semaphore *FASTCALL(rwsem_wake(struct rw_semaphore *));
 24 
 25 struct rw_semaphore {
 26         signed int count;
 27 #define RWSEM_UNLOCKED_VALUE            0x00000000
 28 #define RWSEM_ACTIVE_BIAS               0x00000001
 29 #define RWSEM_ACTIVE_MASK               0x0000ffff
 30 #define RWSEM_WAITING_BIAS              0xffff0000
 31 #define RWSEM_ACTIVE_READ_BIAS          RWSEM_ACTIVE_BIAS
 32 #define RWSEM_ACTIVE_WRITE_BIAS         (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
 33         spinlock_t              wait_lock;
 34         struct list_head        wait_list;
 35 };
 36 
 37 #define __RWSEM_INITIALIZER(name) \
 38 { RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) }
 39 
 40 #define DECLARE_RWSEM(name) \
 41         struct rw_semaphore name = __RWSEM_INITIALIZER(name)
 42 
 43 static inline void init_rwsem(struct rw_semaphore *sem)
 44 {
 45         sem->count = RWSEM_UNLOCKED_VALUE;
 46         spin_lock_init(&sem->wait_lock);
 47         INIT_LIST_HEAD(&sem->wait_list);
 48 }
 49 
 50 static inline void __down_read(struct rw_semaphore *sem)
 51 {
 52         __asm__ __volatile__(
 53                 "! beginning __down_read\n"
 54                 "1:\tlduw       [%0], %%g5\n\t"
 55                 "add            %%g5, 1, %%g7\n\t"
 56                 "cas            [%0], %%g5, %%g7\n\t"
 57                 "cmp            %%g5, %%g7\n\t"
 58                 "bne,pn         %%icc, 1b\n\t"
 59                 " add           %%g7, 1, %%g7\n\t"
 60                 "cmp            %%g7, 0\n\t"
 61                 "bl,pn          %%icc, 3f\n\t"
 62                 " membar        #StoreLoad | #StoreStore\n"
 63                 "2:\n\t"
 64                 ".subsection    2\n"
 65                 "3:\tmov        %0, %%g5\n\t"
 66                 "save           %%sp, -160, %%sp\n\t"
 67                 "mov            %%g1, %%l1\n\t"
 68                 "mov            %%g2, %%l2\n\t"
 69                 "mov            %%g3, %%l3\n\t"
 70                 "call           %1\n\t"
 71                 " mov           %%g5, %%o0\n\t"
 72                 "mov            %%l1, %%g1\n\t"
 73                 "mov            %%l2, %%g2\n\t"
 74                 "ba,pt          %%xcc, 2b\n\t"
 75                 " restore       %%l3, %%g0, %%g3\n\t"
 76                 ".previous\n\t"
 77                 "! ending __down_read"
 78                 : : "r" (sem), "i" (rwsem_down_read_failed)
 79                 : "g5", "g7", "memory", "cc");
 80 }
 81 
 82 static __inline__ int __down_read_trylock(struct rw_semaphore *sem)
 83 {
 84         int result;
 85 
 86         __asm__ __volatile__(
 87                 "! beginning __down_read_trylock\n"
 88                 "1:\tlduw       [%1], %%g5\n\t"
 89                 "add            %%g5, 1, %%g7\n\t"
 90                 "cmp            %%g7, 0\n\t"
 91                 "bl,pn          %%icc, 2f\n\t"
 92                 " mov           0, %0\n\t"
 93                 "cas            [%1], %%g5, %%g7\n\t"
 94                 "cmp            %%g5, %%g7\n\t"
 95                 "bne,pn         %%icc, 1b\n\t"
 96                 " mov           1, %0\n\t"
 97                 "membar         #StoreLoad | #StoreStore\n"
 98                 "2:\n\t"
 99                 "! ending __down_read_trylock"
100                 : "=&r" (result)
101                 : "r" (sem)
102                 : "g5", "g7", "memory", "cc");
103 
104         return result;
105 }
106 
107 static inline void __down_write(struct rw_semaphore *sem)
108 {
109         __asm__ __volatile__(
110                 "! beginning __down_write\n\t"
111                 "sethi          %%hi(%2), %%g1\n\t"
112                 "or             %%g1, %%lo(%2), %%g1\n"
113                 "1:\tlduw       [%0], %%g5\n\t"
114                 "add            %%g5, %%g1, %%g7\n\t"
115                 "cas            [%0], %%g5, %%g7\n\t"
116                 "cmp            %%g5, %%g7\n\t"
117                 "bne,pn         %%icc, 1b\n\t"
118                 " cmp           %%g7, 0\n\t"
119                 "bne,pn         %%icc, 3f\n\t"
120                 " membar        #StoreLoad | #StoreStore\n"
121                 "2:\n\t"
122                 ".subsection    2\n"
123                 "3:\tmov        %0, %%g5\n\t"
124                 "save           %%sp, -160, %%sp\n\t"
125                 "mov            %%g2, %%l2\n\t"
126                 "mov            %%g3, %%l3\n\t"
127                 "call           %1\n\t"
128                 " mov           %%g5, %%o0\n\t"
129                 "mov            %%l2, %%g2\n\t"
130                 "ba,pt          %%xcc, 2b\n\t"
131                 " restore       %%l3, %%g0, %%g3\n\t"
132                 ".previous\n\t"
133                 "! ending __down_write"
134                 : : "r" (sem), "i" (rwsem_down_write_failed),
135                     "i" (RWSEM_ACTIVE_WRITE_BIAS)
136                 : "g1", "g5", "g7", "memory", "cc");
137 }
138 
139 static __inline__ int __down_write_trylock(struct rw_semaphore *sem)
140 {
141         int result;
142 
143         __asm__ __volatile__(
144                 "! beginning __down_write_trylock\n\t"
145                 "sethi          %%hi(%2), %%g1\n\t"
146                 "or             %%g1, %%lo(%2), %%g1\n"
147                 "1:\tlduw       [%1], %%g5\n\t"
148                 "cmp            %%g5, 0\n\t"
149                 "bne,pn         %%icc, 2f\n\t"
150                 " mov           0, %0\n\t"
151                 "add            %%g5, %%g1, %%g7\n\t"
152                 "cas            [%1], %%g5, %%g7\n\t"
153                 "cmp            %%g5, %%g7\n\t"
154                 "bne,pn         %%icc, 1b\n\t"
155                 " mov           1, %0\n\t"
156                 "membar         #StoreLoad | #StoreStore\n"
157                 "2:\n\t"
158                 "! ending __down_write_trylock"
159                 : "=&r" (result)
160                 : "r" (sem), "i" (RWSEM_ACTIVE_WRITE_BIAS)
161                 : "g1", "g5", "g7", "memory", "cc");
162 
163         return result;
164 }
165 
166 static inline void __up_read(struct rw_semaphore *sem)
167 {
168         __asm__ __volatile__(
169                 "! beginning __up_read\n\t"
170                 "1:\tlduw       [%0], %%g5\n\t"
171                 "sub            %%g5, 1, %%g7\n\t"
172                 "cas            [%0], %%g5, %%g7\n\t"
173                 "cmp            %%g5, %%g7\n\t"
174                 "bne,pn         %%icc, 1b\n\t"
175                 " cmp           %%g7, 0\n\t"
176                 "bl,pn          %%icc, 3f\n\t"
177                 " membar        #StoreLoad | #StoreStore\n"
178                 "2:\n\t"
179                 ".subsection    2\n"
180                 "3:\tsethi      %%hi(%2), %%g1\n\t"
181                 "sub            %%g7, 1, %%g7\n\t"
182                 "or             %%g1, %%lo(%2), %%g1\n\t"
183                 "andcc          %%g7, %%g1, %%g0\n\t"
184                 "bne,pn         %%icc, 2b\n\t"
185                 " mov           %0, %%g5\n\t"
186                 "save           %%sp, -160, %%sp\n\t"
187                 "mov            %%g2, %%l2\n\t"
188                 "mov            %%g3, %%l3\n\t"
189                 "call           %1\n\t"
190                 " mov           %%g5, %%o0\n\t"
191                 "mov            %%l2, %%g2\n\t"
192                 "ba,pt          %%xcc, 2b\n\t"
193                 " restore       %%l3, %%g0, %%g3\n\t"
194                 ".previous\n\t"
195                 "! ending __up_read"
196                 : : "r" (sem), "i" (rwsem_wake),
197                     "i" (RWSEM_ACTIVE_MASK)
198                 : "g1", "g5", "g7", "memory", "cc");
199 }
200 
201 static inline void __up_write(struct rw_semaphore *sem)
202 {
203         __asm__ __volatile__(
204                 "! beginning __up_write\n\t"
205                 "sethi          %%hi(%2), %%g1\n\t"
206                 "or             %%g1, %%lo(%2), %%g1\n"
207                 "1:\tlduw       [%0], %%g5\n\t"
208                 "sub            %%g5, %%g1, %%g7\n\t"
209                 "cas            [%0], %%g5, %%g7\n\t"
210                 "cmp            %%g5, %%g7\n\t"
211                 "bne,pn         %%icc, 1b\n\t"
212                 " sub           %%g7, %%g1, %%g7\n\t"
213                 "cmp            %%g7, 0\n\t"
214                 "bl,pn          %%icc, 3f\n\t"
215                 " membar        #StoreLoad | #StoreStore\n"
216                 "2:\n\t"
217                 ".subsection 2\n"
218                 "3:\tmov        %0, %%g5\n\t"
219                 "save           %%sp, -160, %%sp\n\t"
220                 "mov            %%g2, %%l2\n\t"
221                 "mov            %%g3, %%l3\n\t"
222                 "call           %1\n\t"
223                 " mov           %%g5, %%o0\n\t"
224                 "mov            %%l2, %%g2\n\t"
225                 "ba,pt          %%xcc, 2b\n\t"
226                 " restore       %%l3, %%g0, %%g3\n\t"
227                 ".previous\n\t"
228                 "! ending __up_write"
229                 : : "r" (sem), "i" (rwsem_wake),
230                     "i" (RWSEM_ACTIVE_WRITE_BIAS)
231                 : "g1", "g5", "g7", "memory", "cc");
232 }
233 
234 static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
235 {
236         int tmp = delta;
237 
238         __asm__ __volatile__(
239                 "1:\tlduw       [%2], %%g5\n\t"
240                 "add            %%g5, %1, %%g7\n\t"
241                 "cas            [%2], %%g5, %%g7\n\t"
242                 "cmp            %%g5, %%g7\n\t"
243                 "bne,pn         %%icc, 1b\n\t"
244                 " membar        #StoreLoad | #StoreStore\n\t"
245                 "mov            %%g7, %0\n\t"
246                 : "=&r" (tmp)
247                 : "" (tmp), "r" (sem)
248                 : "g5", "g7", "memory");
249 
250         return tmp + delta;
251 }
252 
253 #define rwsem_atomic_add rwsem_atomic_update
254 
255 static inline __u16 rwsem_cmpxchgw(struct rw_semaphore *sem, __u16 __old, __u16 __new)
256 {
257         u32 old = (sem->count & 0xffff0000) | (u32) __old;
258         u32 new = (old & 0xffff0000) | (u32) __new;
259         u32 prev;
260 
261 again:
262         __asm__ __volatile__("cas       [%2], %3, %0\n\t"
263                              "membar    #StoreLoad | #StoreStore"
264                              : "=&r" (prev)
265                              : "" (new), "r" (sem), "r" (old)
266                              : "memory");
267 
268         /* To give the same semantics as x86 cmpxchgw, keep trying
269          * if only the upper 16-bits changed.
270          */
271         if (prev != old &&
272             ((prev & 0xffff) == (old & 0xffff)))
273                 goto again;
274 
275         return prev & 0xffff;
276 }
277 
278 static inline signed long rwsem_cmpxchg(struct rw_semaphore *sem, signed long old, signed long new)
279 {
280         return cmpxchg(&sem->count,old,new);
281 }
282 
283 #endif /* __KERNEL__ */
284 
285 #endif /* _SPARC64_RWSEM_H */
286 

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