1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
|
/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1999, 2000, 06 Ralf Baechle (ralf@linux-mips.org)
* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
*/
#ifndef _ASM_SPINLOCK_H
#define _ASM_SPINLOCK_H
#include <linux/compiler.h>
#include <asm/barrier.h>
#include <asm/compiler.h>
#include <asm/war.h>
/*
* Your basic SMP spinlocks, allowing only a single CPU anywhere
*
* Simple spin lock operations. There are two variants, one clears IRQ's
* on the local processor, one does not.
*
* These are fair FIFO ticket locks
*
* (the type definitions are in asm/spinlock_types.h)
*/
/*
* Ticket locks are conceptually two parts, one indicating the current head of
* the queue, and the other indicating the current tail. The lock is acquired
* by atomically noting the tail and incrementing it by one (thus adding
* ourself to the queue and noting our position), then waiting until the head
* becomes equal to the the initial value of the tail.
*/
static inline int arch_spin_is_locked(arch_spinlock_t *lock)
{
u32 counters = ACCESS_ONCE(lock->lock);
return ((counters >> 16) ^ counters) & 0xffff;
}
#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
#define arch_spin_unlock_wait(x) \
while (arch_spin_is_locked(x)) { cpu_relax(); }
static inline int arch_spin_is_contended(arch_spinlock_t *lock)
{
u32 counters = ACCESS_ONCE(lock->lock);
return (((counters >> 16) - counters) & 0xffff) > 1;
}
#define arch_spin_is_contended arch_spin_is_contended
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
int my_ticket;
int tmp;
int inc = 0x10000;
if (R10000_LLSC_WAR) {
__asm__ __volatile__ (
" .set push # arch_spin_lock \n"
" .set noreorder \n"
" \n"
"1: ll %[ticket], %[ticket_ptr] \n"
" addu %[my_ticket], %[ticket], %[inc] \n"
" sc %[my_ticket], %[ticket_ptr] \n"
" beqzl %[my_ticket], 1b \n"
" nop \n"
" srl %[my_ticket], %[ticket], 16 \n"
" andi %[ticket], %[ticket], 0xffff \n"
" bne %[ticket], %[my_ticket], 4f \n"
" subu %[ticket], %[my_ticket], %[ticket] \n"
"2: \n"
" .subsection 2 \n"
"4: andi %[ticket], %[ticket], 0xffff \n"
" sll %[ticket], 5 \n"
" \n"
"6: bnez %[ticket], 6b \n"
" subu %[ticket], 1 \n"
" \n"
" lhu %[ticket], %[serving_now_ptr] \n"
" beq %[ticket], %[my_ticket], 2b \n"
" subu %[ticket], %[my_ticket], %[ticket] \n"
" b 4b \n"
" subu %[ticket], %[ticket], 1 \n"
" .previous \n"
" .set pop \n"
: [ticket_ptr] "+" GCC_OFF_SMALL_ASM() (lock->lock),
[serving_now_ptr] "+m" (lock->h.serving_now),
[ticket] "=&r" (tmp),
[my_ticket] "=&r" (my_ticket)
: [inc] "r" (inc));
} else {
__asm__ __volatile__ (
" .set push # arch_spin_lock \n"
" .set noreorder \n"
" \n"
"1: ll %[ticket], %[ticket_ptr] \n"
" addu %[my_ticket], %[ticket], %[inc] \n"
" sc %[my_ticket], %[ticket_ptr] \n"
" beqz %[my_ticket], 1b \n"
" srl %[my_ticket], %[ticket], 16 \n"
" andi %[ticket], %[ticket], 0xffff \n"
" bne %[ticket], %[my_ticket], 4f \n"
" subu %[ticket], %[my_ticket], %[ticket] \n"
"2: \n"
" .subsection 2 \n"
"4: andi %[ticket], %[ticket], 0x1fff \n"
" sll %[ticket], 5 \n"
" \n"
"6: bnez %[ticket], 6b \n"
" subu %[ticket], 1 \n"
" \n"
" lhu %[ticket], %[serving_now_ptr] \n"
" beq %[ticket], %[my_ticket], 2b \n"
" subu %[ticket], %[my_ticket], %[ticket] \n"
" b 4b \n"
" subu %[ticket], %[ticket], 1 \n"
" .previous \n"
" .set pop \n"
: [ticket_ptr] "+" GCC_OFF_SMALL_ASM() (lock->lock),
[serving_now_ptr] "+m" (lock->h.serving_now),
[ticket] "=&r" (tmp),
[my_ticket] "=&r" (my_ticket)
: [inc] "r" (inc));
}
smp_llsc_mb();
}
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
unsigned int serving_now = lock->h.serving_now + 1;
wmb();
lock->h.serving_now = (u16)serving_now;
nudge_writes();
}
static inline unsigned int arch_spin_trylock(arch_spinlock_t *lock)
{
int tmp, tmp2, tmp3;
int inc = 0x10000;
if (R10000_LLSC_WAR) {
__asm__ __volatile__ (
" .set push # arch_spin_trylock \n"
" .set noreorder \n"
" \n"
"1: ll %[ticket], %[ticket_ptr] \n"
" srl %[my_ticket], %[ticket], 16 \n"
" andi %[now_serving], %[ticket], 0xffff \n"
" bne %[my_ticket], %[now_serving], 3f \n"
" addu %[ticket], %[ticket], %[inc] \n"
" sc %[ticket], %[ticket_ptr] \n"
" beqzl %[ticket], 1b \n"
" li %[ticket], 1 \n"
"2: \n"
" .subsection 2 \n"
"3: b 2b \n"
" li %[ticket], 0 \n"
" .previous \n"
" .set pop \n"
: [ticket_ptr] "+" GCC_OFF_SMALL_ASM() (lock->lock),
[ticket] "=&r" (tmp),
[my_ticket] "=&r" (tmp2),
[now_serving] "=&r" (tmp3)
: [inc] "r" (inc));
} else {
__asm__ __volatile__ (
" .set push # arch_spin_trylock \n"
" .set noreorder \n"
" \n"
"1: ll %[ticket], %[ticket_ptr] \n"
" srl %[my_ticket], %[ticket], 16 \n"
" andi %[now_serving], %[ticket], 0xffff \n"
" bne %[my_ticket], %[now_serving], 3f \n"
" addu %[ticket], %[ticket], %[inc] \n"
" sc %[ticket], %[ticket_ptr] \n"
" beqz %[ticket], 1b \n"
" li %[ticket], 1 \n"
"2: \n"
" .subsection 2 \n"
"3: b 2b \n"
" li %[ticket], 0 \n"
" .previous \n"
" .set pop \n"
: [ticket_ptr] "+" GCC_OFF_SMALL_ASM() (lock->lock),
[ticket] "=&r" (tmp),
[my_ticket] "=&r" (tmp2),
[now_serving] "=&r" (tmp3)
: [inc] "r" (inc));
}
smp_llsc_mb();
return tmp;
}
/*
* Read-write spinlocks, allowing multiple readers but only one writer.
*
* NOTE! it is quite common to have readers in interrupts but no interrupt
* writers. For those circumstances we can "mix" irq-safe locks - any writer
* needs to get a irq-safe write-lock, but readers can get non-irqsafe
* read-locks.
*/
/*
* read_can_lock - would read_trylock() succeed?
* @lock: the rwlock in question.
*/
#define arch_read_can_lock(rw) ((rw)->lock >= 0)
/*
* write_can_lock - would write_trylock() succeed?
* @lock: the rwlock in question.
*/
#define arch_write_can_lock(rw) (!(rw)->lock)
static inline void arch_read_lock(arch_rwlock_t *rw)
{
unsigned int tmp;
if (R10000_LLSC_WAR) {
__asm__ __volatile__(
" .set noreorder # arch_read_lock \n"
"1: ll %1, %2 \n"
" bltz %1, 1b \n"
" addu %1, 1 \n"
" sc %1, %0 \n"
" beqzl %1, 1b \n"
" nop \n"
" .set reorder \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} else {
do {
__asm__ __volatile__(
"1: ll %1, %2 # arch_read_lock \n"
" bltz %1, 1b \n"
" addu %1, 1 \n"
"2: sc %1, %0 \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} while (unlikely(!tmp));
}
smp_llsc_mb();
}
static inline void arch_read_unlock(arch_rwlock_t *rw)
{
unsigned int tmp;
smp_mb__before_llsc();
if (R10000_LLSC_WAR) {
__asm__ __volatile__(
"1: ll %1, %2 # arch_read_unlock \n"
" addiu %1, 1 \n"
" sc %1, %0 \n"
" beqzl %1, 1b \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} else {
do {
__asm__ __volatile__(
"1: ll %1, %2 # arch_read_unlock \n"
" addiu %1, -1 \n"
" sc %1, %0 \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} while (unlikely(!tmp));
}
}
static inline void arch_write_lock(arch_rwlock_t *rw)
{
unsigned int tmp;
if (R10000_LLSC_WAR) {
__asm__ __volatile__(
" .set noreorder # arch_write_lock \n"
"1: ll %1, %2 \n"
" bnez %1, 1b \n"
" lui %1, 0x8000 \n"
" sc %1, %0 \n"
" beqzl %1, 1b \n"
" nop \n"
" .set reorder \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} else {
do {
__asm__ __volatile__(
"1: ll %1, %2 # arch_write_lock \n"
" bnez %1, 1b \n"
" lui %1, 0x8000 \n"
"2: sc %1, %0 \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} while (unlikely(!tmp));
}
smp_llsc_mb();
}
static inline void arch_write_unlock(arch_rwlock_t *rw)
{
smp_mb();
__asm__ __volatile__(
" # arch_write_unlock \n"
" sw $0, %0 \n"
: "=m" (rw->lock)
: "m" (rw->lock)
: "memory");
}
static inline int arch_read_trylock(arch_rwlock_t *rw)
{
unsigned int tmp;
int ret;
if (R10000_LLSC_WAR) {
__asm__ __volatile__(
" .set noreorder # arch_read_trylock \n"
" li %2, 0 \n"
"1: ll %1, %3 \n"
" bltz %1, 2f \n"
" addu %1, 1 \n"
" sc %1, %0 \n"
" .set reorder \n"
" beqzl %1, 1b \n"
" nop \n"
__WEAK_LLSC_MB
" li %2, 1 \n"
"2: \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp), "=&r" (ret)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} else {
__asm__ __volatile__(
" .set noreorder # arch_read_trylock \n"
" li %2, 0 \n"
"1: ll %1, %3 \n"
" bltz %1, 2f \n"
" addu %1, 1 \n"
" sc %1, %0 \n"
" beqz %1, 1b \n"
" nop \n"
" .set reorder \n"
__WEAK_LLSC_MB
" li %2, 1 \n"
"2: \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp), "=&r" (ret)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
}
return ret;
}
static inline int arch_write_trylock(arch_rwlock_t *rw)
{
unsigned int tmp;
int ret;
if (R10000_LLSC_WAR) {
__asm__ __volatile__(
" .set noreorder # arch_write_trylock \n"
" li %2, 0 \n"
"1: ll %1, %3 \n"
" bnez %1, 2f \n"
" lui %1, 0x8000 \n"
" sc %1, %0 \n"
" beqzl %1, 1b \n"
" nop \n"
__WEAK_LLSC_MB
" li %2, 1 \n"
" .set reorder \n"
"2: \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp), "=&r" (ret)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} else {
do {
__asm__ __volatile__(
" ll %1, %3 # arch_write_trylock \n"
" li %2, 0 \n"
" bnez %1, 2f \n"
" lui %1, 0x8000 \n"
" sc %1, %0 \n"
" li %2, 1 \n"
"2: \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp),
"=&r" (ret)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} while (unlikely(!tmp));
smp_llsc_mb();
}
return ret;
}
#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
#define arch_spin_relax(lock) cpu_relax()
#define arch_read_relax(lock) cpu_relax()
#define arch_write_relax(lock) cpu_relax()
#endif /* _ASM_SPINLOCK_H */
|
