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Linux/arch/ia64/include/asm/spinlock.h

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  1 #ifndef _ASM_IA64_SPINLOCK_H
  2 #define _ASM_IA64_SPINLOCK_H
  3 
  4 /*
  5  * Copyright (C) 1998-2003 Hewlett-Packard Co
  6  *      David Mosberger-Tang <davidm@hpl.hp.com>
  7  * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
  8  *
  9  * This file is used for SMP configurations only.
 10  */
 11 
 12 #include <linux/compiler.h>
 13 #include <linux/kernel.h>
 14 #include <linux/bitops.h>
 15 
 16 #include <asm/atomic.h>
 17 #include <asm/intrinsics.h>
 18 #include <asm/system.h>
 19 
 20 #define __raw_spin_lock_init(x)                 ((x)->lock = 0)
 21 
 22 /*
 23  * Ticket locks are conceptually two parts, one indicating the current head of
 24  * the queue, and the other indicating the current tail. The lock is acquired
 25  * by atomically noting the tail and incrementing it by one (thus adding
 26  * ourself to the queue and noting our position), then waiting until the head
 27  * becomes equal to the the initial value of the tail.
 28  * The pad bits in the middle are used to prevent the next_ticket number
 29  * overflowing into the now_serving number.
 30  *
 31  *   31             17  16    15  14                    0
 32  *  +----------------------------------------------------+
 33  *  |  now_serving     | padding |   next_ticket         |
 34  *  +----------------------------------------------------+
 35  */
 36 
 37 #define TICKET_SHIFT    17
 38 #define TICKET_BITS     15
 39 #define TICKET_MASK     ((1 << TICKET_BITS) - 1)
 40 
 41 static __always_inline void __ticket_spin_lock(raw_spinlock_t *lock)
 42 {
 43         int     *p = (int *)&lock->lock, ticket, serve;
 44 
 45         ticket = ia64_fetchadd(1, p, acq);
 46 
 47         if (!(((ticket >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))
 48                 return;
 49 
 50         ia64_invala();
 51 
 52         for (;;) {
 53                 asm volatile ("ld4.c.nc %0=[%1]" : "=r"(serve) : "r"(p) : "memory");
 54 
 55                 if (!(((serve >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))
 56                         return;
 57                 cpu_relax();
 58         }
 59 }
 60 
 61 static __always_inline int __ticket_spin_trylock(raw_spinlock_t *lock)
 62 {
 63         int tmp = ACCESS_ONCE(lock->lock);
 64 
 65         if (!(((tmp >> TICKET_SHIFT) ^ tmp) & TICKET_MASK))
 66                 return ia64_cmpxchg(acq, &lock->lock, tmp, tmp + 1, sizeof (tmp)) == tmp;
 67         return 0;
 68 }
 69 
 70 static __always_inline void __ticket_spin_unlock(raw_spinlock_t *lock)
 71 {
 72         unsigned short  *p = (unsigned short *)&lock->lock + 1, tmp;
 73 
 74         asm volatile ("ld2.bias %0=[%1]" : "=r"(tmp) : "r"(p));
 75         ACCESS_ONCE(*p) = (tmp + 2) & ~1;
 76 }
 77 
 78 static __always_inline void __ticket_spin_unlock_wait(raw_spinlock_t *lock)
 79 {
 80         int     *p = (int *)&lock->lock, ticket;
 81 
 82         ia64_invala();
 83 
 84         for (;;) {
 85                 asm volatile ("ld4.c.nc %0=[%1]" : "=r"(ticket) : "r"(p) : "memory");
 86                 if (!(((ticket >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))
 87                         return;
 88                 cpu_relax();
 89         }
 90 }
 91 
 92 static inline int __ticket_spin_is_locked(raw_spinlock_t *lock)
 93 {
 94         long tmp = ACCESS_ONCE(lock->lock);
 95 
 96         return !!(((tmp >> TICKET_SHIFT) ^ tmp) & TICKET_MASK);
 97 }
 98 
 99 static inline int __ticket_spin_is_contended(raw_spinlock_t *lock)
100 {
101         long tmp = ACCESS_ONCE(lock->lock);
102 
103         return ((tmp - (tmp >> TICKET_SHIFT)) & TICKET_MASK) > 1;
104 }
105 
106 static inline int __raw_spin_is_locked(raw_spinlock_t *lock)
107 {
108         return __ticket_spin_is_locked(lock);
109 }
110 
111 static inline int __raw_spin_is_contended(raw_spinlock_t *lock)
112 {
113         return __ticket_spin_is_contended(lock);
114 }
115 #define __raw_spin_is_contended __raw_spin_is_contended
116 
117 static __always_inline void __raw_spin_lock(raw_spinlock_t *lock)
118 {
119         __ticket_spin_lock(lock);
120 }
121 
122 static __always_inline int __raw_spin_trylock(raw_spinlock_t *lock)
123 {
124         return __ticket_spin_trylock(lock);
125 }
126 
127 static __always_inline void __raw_spin_unlock(raw_spinlock_t *lock)
128 {
129         __ticket_spin_unlock(lock);
130 }
131 
132 static __always_inline void __raw_spin_lock_flags(raw_spinlock_t *lock,
133                                                   unsigned long flags)
134 {
135         __raw_spin_lock(lock);
136 }
137 
138 static inline void __raw_spin_unlock_wait(raw_spinlock_t *lock)
139 {
140         __ticket_spin_unlock_wait(lock);
141 }
142 
143 #define __raw_read_can_lock(rw)         (*(volatile int *)(rw) >= 0)
144 #define __raw_write_can_lock(rw)        (*(volatile int *)(rw) == 0)
145 
146 #ifdef ASM_SUPPORTED
147 
148 static __always_inline void
149 __raw_read_lock_flags(raw_rwlock_t *lock, unsigned long flags)
150 {
151         __asm__ __volatile__ (
152                 "tbit.nz p6, p0 = %1,%2\n"
153                 "br.few 3f\n"
154                 "1:\n"
155                 "fetchadd4.rel r2 = [%0], -1;;\n"
156                 "(p6) ssm psr.i\n"
157                 "2:\n"
158                 "hint @pause\n"
159                 "ld4 r2 = [%0];;\n"
160                 "cmp4.lt p7,p0 = r2, r0\n"
161                 "(p7) br.cond.spnt.few 2b\n"
162                 "(p6) rsm psr.i\n"
163                 ";;\n"
164                 "3:\n"
165                 "fetchadd4.acq r2 = [%0], 1;;\n"
166                 "cmp4.lt p7,p0 = r2, r0\n"
167                 "(p7) br.cond.spnt.few 1b\n"
168                 : : "r"(lock), "r"(flags), "i"(IA64_PSR_I_BIT)
169                 : "p6", "p7", "r2", "memory");
170 }
171 
172 #define __raw_read_lock(lock) __raw_read_lock_flags(lock, 0)
173 
174 #else /* !ASM_SUPPORTED */
175 
176 #define __raw_read_lock_flags(rw, flags) __raw_read_lock(rw)
177 
178 #define __raw_read_lock(rw)                                                             \
179 do {                                                                                    \
180         raw_rwlock_t *__read_lock_ptr = (rw);                                           \
181                                                                                         \
182         while (unlikely(ia64_fetchadd(1, (int *) __read_lock_ptr, acq) < 0)) {          \
183                 ia64_fetchadd(-1, (int *) __read_lock_ptr, rel);                        \
184                 while (*(volatile int *)__read_lock_ptr < 0)                            \
185                         cpu_relax();                                                    \
186         }                                                                               \
187 } while (0)
188 
189 #endif /* !ASM_SUPPORTED */
190 
191 #define __raw_read_unlock(rw)                                   \
192 do {                                                            \
193         raw_rwlock_t *__read_lock_ptr = (rw);                   \
194         ia64_fetchadd(-1, (int *) __read_lock_ptr, rel);        \
195 } while (0)
196 
197 #ifdef ASM_SUPPORTED
198 
199 static __always_inline void
200 __raw_write_lock_flags(raw_rwlock_t *lock, unsigned long flags)
201 {
202         __asm__ __volatile__ (
203                 "tbit.nz p6, p0 = %1, %2\n"
204                 "mov ar.ccv = r0\n"
205                 "dep r29 = -1, r0, 31, 1\n"
206                 "br.few 3f;;\n"
207                 "1:\n"
208                 "(p6) ssm psr.i\n"
209                 "2:\n"
210                 "hint @pause\n"
211                 "ld4 r2 = [%0];;\n"
212                 "cmp4.eq p0,p7 = r0, r2\n"
213                 "(p7) br.cond.spnt.few 2b\n"
214                 "(p6) rsm psr.i\n"
215                 ";;\n"
216                 "3:\n"
217                 "cmpxchg4.acq r2 = [%0], r29, ar.ccv;;\n"
218                 "cmp4.eq p0,p7 = r0, r2\n"
219                 "(p7) br.cond.spnt.few 1b;;\n"
220                 : : "r"(lock), "r"(flags), "i"(IA64_PSR_I_BIT)
221                 : "ar.ccv", "p6", "p7", "r2", "r29", "memory");
222 }
223 
224 #define __raw_write_lock(rw) __raw_write_lock_flags(rw, 0)
225 
226 #define __raw_write_trylock(rw)                                                 \
227 ({                                                                              \
228         register long result;                                                   \
229                                                                                 \
230         __asm__ __volatile__ (                                                  \
231                 "mov ar.ccv = r0\n"                                             \
232                 "dep r29 = -1, r0, 31, 1;;\n"                                   \
233                 "cmpxchg4.acq %0 = [%1], r29, ar.ccv\n"                         \
234                 : "=r"(result) : "r"(rw) : "ar.ccv", "r29", "memory");          \
235         (result == 0);                                                          \
236 })
237 
238 static inline void __raw_write_unlock(raw_rwlock_t *x)
239 {
240         u8 *y = (u8 *)x;
241         barrier();
242         asm volatile ("st1.rel.nta [%0] = r0\n\t" :: "r"(y+3) : "memory" );
243 }
244 
245 #else /* !ASM_SUPPORTED */
246 
247 #define __raw_write_lock_flags(l, flags) __raw_write_lock(l)
248 
249 #define __raw_write_lock(l)                                                             \
250 ({                                                                                      \
251         __u64 ia64_val, ia64_set_val = ia64_dep_mi(-1, 0, 31, 1);                       \
252         __u32 *ia64_write_lock_ptr = (__u32 *) (l);                                     \
253         do {                                                                            \
254                 while (*ia64_write_lock_ptr)                                            \
255                         ia64_barrier();                                                 \
256                 ia64_val = ia64_cmpxchg4_acq(ia64_write_lock_ptr, ia64_set_val, 0);     \
257         } while (ia64_val);                                                             \
258 })
259 
260 #define __raw_write_trylock(rw)                                         \
261 ({                                                                      \
262         __u64 ia64_val;                                                 \
263         __u64 ia64_set_val = ia64_dep_mi(-1, 0, 31,1);                  \
264         ia64_val = ia64_cmpxchg4_acq((__u32 *)(rw), ia64_set_val, 0);   \
265         (ia64_val == 0);                                                \
266 })
267 
268 static inline void __raw_write_unlock(raw_rwlock_t *x)
269 {
270         barrier();
271         x->write_lock = 0;
272 }
273 
274 #endif /* !ASM_SUPPORTED */
275 
276 static inline int __raw_read_trylock(raw_rwlock_t *x)
277 {
278         union {
279                 raw_rwlock_t lock;
280                 __u32 word;
281         } old, new;
282         old.lock = new.lock = *x;
283         old.lock.write_lock = new.lock.write_lock = 0;
284         ++new.lock.read_counter;
285         return (u32)ia64_cmpxchg4_acq((__u32 *)(x), new.word, old.word) == old.word;
286 }
287 
288 #define _raw_spin_relax(lock)   cpu_relax()
289 #define _raw_read_relax(lock)   cpu_relax()
290 #define _raw_write_relax(lock)  cpu_relax()
291 
292 #endif /*  _ASM_IA64_SPINLOCK_H */
293 

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