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1da177e4 LT |
1 | #ifndef __ASM_SPINLOCK_H |
2 | #define __ASM_SPINLOCK_H | |
88ced031 | 3 | #ifdef __KERNEL__ |
1da177e4 LT |
4 | |
5 | /* | |
6 | * Simple spin lock operations. | |
7 | * | |
8 | * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM | |
9 | * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM | |
10 | * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM | |
11 | * Rework to support virtual processors | |
12 | * | |
13 | * Type of int is used as a full 64b word is not necessary. | |
14 | * | |
15 | * This program is free software; you can redistribute it and/or | |
16 | * modify it under the terms of the GNU General Public License | |
17 | * as published by the Free Software Foundation; either version | |
18 | * 2 of the License, or (at your option) any later version. | |
fb1c8f93 IM |
19 | * |
20 | * (the type definitions are in asm/spinlock_types.h) | |
1da177e4 | 21 | */ |
945feb17 | 22 | #include <linux/irqflags.h> |
0212ddd8 | 23 | #ifdef CONFIG_PPC64 |
1da177e4 LT |
24 | #include <asm/paca.h> |
25 | #include <asm/hvcall.h> | |
0212ddd8 PM |
26 | #endif |
27 | #include <asm/asm-compat.h> | |
28 | #include <asm/synch.h> | |
4e14a4d1 | 29 | #include <asm/ppc-opcode.h> |
1da177e4 | 30 | |
0212ddd8 PM |
31 | #ifdef CONFIG_PPC64 |
32 | /* use 0x800000yy when locked, where yy == CPU number */ | |
54bb7f4b | 33 | #ifdef __BIG_ENDIAN__ |
0212ddd8 PM |
34 | #define LOCK_TOKEN (*(u32 *)(&get_paca()->lock_token)) |
35 | #else | |
54bb7f4b AB |
36 | #define LOCK_TOKEN (*(u32 *)(&get_paca()->paca_index)) |
37 | #endif | |
38 | #else | |
0212ddd8 PM |
39 | #define LOCK_TOKEN 1 |
40 | #endif | |
41 | ||
f007cacf PM |
42 | #if defined(CONFIG_PPC64) && defined(CONFIG_SMP) |
43 | #define CLEAR_IO_SYNC (get_paca()->io_sync = 0) | |
44 | #define SYNC_IO do { \ | |
45 | if (unlikely(get_paca()->io_sync)) { \ | |
46 | mb(); \ | |
47 | get_paca()->io_sync = 0; \ | |
48 | } \ | |
49 | } while (0) | |
50 | #else | |
51 | #define CLEAR_IO_SYNC | |
52 | #define SYNC_IO | |
53 | #endif | |
54 | ||
3405d230 ME |
55 | static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock) |
56 | { | |
57 | return lock.slock == 0; | |
58 | } | |
59 | ||
7179ba52 ME |
60 | static inline int arch_spin_is_locked(arch_spinlock_t *lock) |
61 | { | |
51d7d520 | 62 | smp_mb(); |
7179ba52 ME |
63 | return !arch_spin_value_unlocked(*lock); |
64 | } | |
65 | ||
fb1c8f93 IM |
66 | /* |
67 | * This returns the old value in the lock, so we succeeded | |
68 | * in getting the lock if the return value is 0. | |
69 | */ | |
0199c4e6 | 70 | static inline unsigned long __arch_spin_trylock(arch_spinlock_t *lock) |
fb1c8f93 | 71 | { |
0212ddd8 | 72 | unsigned long tmp, token; |
1da177e4 | 73 | |
0212ddd8 | 74 | token = LOCK_TOKEN; |
fb1c8f93 | 75 | __asm__ __volatile__( |
4e14a4d1 | 76 | "1: " PPC_LWARX(%0,0,%2,1) "\n\ |
fb1c8f93 IM |
77 | cmpwi 0,%0,0\n\ |
78 | bne- 2f\n\ | |
79 | stwcx. %1,0,%2\n\ | |
f10e2e5b AB |
80 | bne- 1b\n" |
81 | PPC_ACQUIRE_BARRIER | |
82 | "2:" | |
83 | : "=&r" (tmp) | |
0212ddd8 | 84 | : "r" (token), "r" (&lock->slock) |
fb1c8f93 | 85 | : "cr0", "memory"); |
1da177e4 | 86 | |
fb1c8f93 IM |
87 | return tmp; |
88 | } | |
1da177e4 | 89 | |
0199c4e6 | 90 | static inline int arch_spin_trylock(arch_spinlock_t *lock) |
1da177e4 | 91 | { |
f007cacf | 92 | CLEAR_IO_SYNC; |
0199c4e6 | 93 | return __arch_spin_trylock(lock) == 0; |
1da177e4 LT |
94 | } |
95 | ||
96 | /* | |
97 | * On a system with shared processors (that is, where a physical | |
98 | * processor is multiplexed between several virtual processors), | |
99 | * there is no point spinning on a lock if the holder of the lock | |
100 | * isn't currently scheduled on a physical processor. Instead | |
101 | * we detect this situation and ask the hypervisor to give the | |
102 | * rest of our timeslice to the lock holder. | |
103 | * | |
104 | * So that we can tell which virtual processor is holding a lock, | |
105 | * we put 0x80000000 | smp_processor_id() in the lock when it is | |
106 | * held. Conveniently, we have a word in the paca that holds this | |
107 | * value. | |
108 | */ | |
109 | ||
1b041885 | 110 | #if defined(CONFIG_PPC_SPLPAR) |
1da177e4 | 111 | /* We only yield to the hypervisor if we are in shared processor mode */ |
f13c13a0 | 112 | #define SHARED_PROCESSOR (lppaca_shared_proc(local_paca->lppaca_ptr)) |
445c8951 | 113 | extern void __spin_yield(arch_spinlock_t *lock); |
fb3a6bbc | 114 | extern void __rw_yield(arch_rwlock_t *lock); |
1b041885 | 115 | #else /* SPLPAR */ |
1da177e4 LT |
116 | #define __spin_yield(x) barrier() |
117 | #define __rw_yield(x) barrier() | |
118 | #define SHARED_PROCESSOR 0 | |
119 | #endif | |
1da177e4 | 120 | |
0199c4e6 | 121 | static inline void arch_spin_lock(arch_spinlock_t *lock) |
1da177e4 | 122 | { |
f007cacf | 123 | CLEAR_IO_SYNC; |
1da177e4 | 124 | while (1) { |
0199c4e6 | 125 | if (likely(__arch_spin_trylock(lock) == 0)) |
1da177e4 LT |
126 | break; |
127 | do { | |
128 | HMT_low(); | |
129 | if (SHARED_PROCESSOR) | |
130 | __spin_yield(lock); | |
fb1c8f93 | 131 | } while (unlikely(lock->slock != 0)); |
1da177e4 LT |
132 | HMT_medium(); |
133 | } | |
134 | } | |
135 | ||
89b5810f | 136 | static inline |
0199c4e6 | 137 | void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags) |
1da177e4 LT |
138 | { |
139 | unsigned long flags_dis; | |
140 | ||
f007cacf | 141 | CLEAR_IO_SYNC; |
1da177e4 | 142 | while (1) { |
0199c4e6 | 143 | if (likely(__arch_spin_trylock(lock) == 0)) |
1da177e4 LT |
144 | break; |
145 | local_save_flags(flags_dis); | |
146 | local_irq_restore(flags); | |
147 | do { | |
148 | HMT_low(); | |
149 | if (SHARED_PROCESSOR) | |
150 | __spin_yield(lock); | |
fb1c8f93 | 151 | } while (unlikely(lock->slock != 0)); |
1da177e4 LT |
152 | HMT_medium(); |
153 | local_irq_restore(flags_dis); | |
154 | } | |
155 | } | |
156 | ||
0199c4e6 | 157 | static inline void arch_spin_unlock(arch_spinlock_t *lock) |
fb1c8f93 | 158 | { |
f007cacf | 159 | SYNC_IO; |
0199c4e6 | 160 | __asm__ __volatile__("# arch_spin_unlock\n\t" |
f10e2e5b | 161 | PPC_RELEASE_BARRIER: : :"memory"); |
fb1c8f93 IM |
162 | lock->slock = 0; |
163 | } | |
164 | ||
6262db7c BF |
165 | static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) |
166 | { | |
167 | arch_spinlock_t lock_val; | |
168 | ||
169 | smp_mb(); | |
170 | ||
171 | /* | |
172 | * Atomically load and store back the lock value (unchanged). This | |
173 | * ensures that our observation of the lock value is ordered with | |
174 | * respect to other lock operations. | |
175 | */ | |
176 | __asm__ __volatile__( | |
177 | "1: " PPC_LWARX(%0, 0, %2, 0) "\n" | |
178 | " stwcx. %0, 0, %2\n" | |
179 | " bne- 1b\n" | |
180 | : "=&r" (lock_val), "+m" (*lock) | |
181 | : "r" (lock) | |
182 | : "cr0", "xer"); | |
183 | ||
184 | if (arch_spin_value_unlocked(lock_val)) | |
185 | goto out; | |
186 | ||
187 | while (lock->slock) { | |
188 | HMT_low(); | |
189 | if (SHARED_PROCESSOR) | |
190 | __spin_yield(lock); | |
191 | } | |
192 | HMT_medium(); | |
193 | ||
194 | out: | |
195 | smp_mb(); | |
196 | } | |
fb1c8f93 | 197 | |
1da177e4 LT |
198 | /* |
199 | * Read-write spinlocks, allowing multiple readers | |
200 | * but only one writer. | |
201 | * | |
202 | * NOTE! it is quite common to have readers in interrupts | |
203 | * but no interrupt writers. For those circumstances we | |
204 | * can "mix" irq-safe locks - any writer needs to get a | |
205 | * irq-safe write-lock, but readers can get non-irqsafe | |
206 | * read-locks. | |
207 | */ | |
1da177e4 | 208 | |
e5931943 TG |
209 | #define arch_read_can_lock(rw) ((rw)->lock >= 0) |
210 | #define arch_write_can_lock(rw) (!(rw)->lock) | |
1da177e4 | 211 | |
0212ddd8 PM |
212 | #ifdef CONFIG_PPC64 |
213 | #define __DO_SIGN_EXTEND "extsw %0,%0\n" | |
214 | #define WRLOCK_TOKEN LOCK_TOKEN /* it's negative */ | |
215 | #else | |
216 | #define __DO_SIGN_EXTEND | |
217 | #define WRLOCK_TOKEN (-1) | |
218 | #endif | |
219 | ||
1da177e4 LT |
220 | /* |
221 | * This returns the old value in the lock + 1, | |
222 | * so we got a read lock if the return value is > 0. | |
223 | */ | |
e5931943 | 224 | static inline long __arch_read_trylock(arch_rwlock_t *rw) |
1da177e4 LT |
225 | { |
226 | long tmp; | |
227 | ||
228 | __asm__ __volatile__( | |
4e14a4d1 | 229 | "1: " PPC_LWARX(%0,0,%1,1) "\n" |
0212ddd8 PM |
230 | __DO_SIGN_EXTEND |
231 | " addic. %0,%0,1\n\ | |
232 | ble- 2f\n" | |
233 | PPC405_ERR77(0,%1) | |
234 | " stwcx. %0,0,%1\n\ | |
f10e2e5b AB |
235 | bne- 1b\n" |
236 | PPC_ACQUIRE_BARRIER | |
237 | "2:" : "=&r" (tmp) | |
1da177e4 LT |
238 | : "r" (&rw->lock) |
239 | : "cr0", "xer", "memory"); | |
240 | ||
241 | return tmp; | |
242 | } | |
243 | ||
1da177e4 LT |
244 | /* |
245 | * This returns the old value in the lock, | |
246 | * so we got the write lock if the return value is 0. | |
247 | */ | |
e5931943 | 248 | static inline long __arch_write_trylock(arch_rwlock_t *rw) |
1da177e4 | 249 | { |
0212ddd8 | 250 | long tmp, token; |
1da177e4 | 251 | |
0212ddd8 | 252 | token = WRLOCK_TOKEN; |
1da177e4 | 253 | __asm__ __volatile__( |
4e14a4d1 | 254 | "1: " PPC_LWARX(%0,0,%2,1) "\n\ |
1da177e4 | 255 | cmpwi 0,%0,0\n\ |
0212ddd8 PM |
256 | bne- 2f\n" |
257 | PPC405_ERR77(0,%1) | |
258 | " stwcx. %1,0,%2\n\ | |
f10e2e5b AB |
259 | bne- 1b\n" |
260 | PPC_ACQUIRE_BARRIER | |
261 | "2:" : "=&r" (tmp) | |
0212ddd8 | 262 | : "r" (token), "r" (&rw->lock) |
1da177e4 LT |
263 | : "cr0", "memory"); |
264 | ||
265 | return tmp; | |
266 | } | |
267 | ||
e5931943 | 268 | static inline void arch_read_lock(arch_rwlock_t *rw) |
1da177e4 | 269 | { |
fb1c8f93 | 270 | while (1) { |
e5931943 | 271 | if (likely(__arch_read_trylock(rw) > 0)) |
fb1c8f93 IM |
272 | break; |
273 | do { | |
274 | HMT_low(); | |
275 | if (SHARED_PROCESSOR) | |
276 | __rw_yield(rw); | |
277 | } while (unlikely(rw->lock < 0)); | |
278 | HMT_medium(); | |
279 | } | |
1da177e4 LT |
280 | } |
281 | ||
e5931943 | 282 | static inline void arch_write_lock(arch_rwlock_t *rw) |
1da177e4 LT |
283 | { |
284 | while (1) { | |
e5931943 | 285 | if (likely(__arch_write_trylock(rw) == 0)) |
1da177e4 LT |
286 | break; |
287 | do { | |
288 | HMT_low(); | |
289 | if (SHARED_PROCESSOR) | |
290 | __rw_yield(rw); | |
d637413f | 291 | } while (unlikely(rw->lock != 0)); |
1da177e4 LT |
292 | HMT_medium(); |
293 | } | |
294 | } | |
295 | ||
e5931943 | 296 | static inline int arch_read_trylock(arch_rwlock_t *rw) |
fb1c8f93 | 297 | { |
e5931943 | 298 | return __arch_read_trylock(rw) > 0; |
fb1c8f93 IM |
299 | } |
300 | ||
e5931943 | 301 | static inline int arch_write_trylock(arch_rwlock_t *rw) |
fb1c8f93 | 302 | { |
e5931943 | 303 | return __arch_write_trylock(rw) == 0; |
fb1c8f93 IM |
304 | } |
305 | ||
e5931943 | 306 | static inline void arch_read_unlock(arch_rwlock_t *rw) |
fb1c8f93 IM |
307 | { |
308 | long tmp; | |
309 | ||
310 | __asm__ __volatile__( | |
144b9c13 | 311 | "# read_unlock\n\t" |
f10e2e5b | 312 | PPC_RELEASE_BARRIER |
144b9c13 | 313 | "1: lwarx %0,0,%1\n\ |
0212ddd8 PM |
314 | addic %0,%0,-1\n" |
315 | PPC405_ERR77(0,%1) | |
316 | " stwcx. %0,0,%1\n\ | |
fb1c8f93 IM |
317 | bne- 1b" |
318 | : "=&r"(tmp) | |
319 | : "r"(&rw->lock) | |
efc3624c | 320 | : "cr0", "xer", "memory"); |
fb1c8f93 IM |
321 | } |
322 | ||
e5931943 | 323 | static inline void arch_write_unlock(arch_rwlock_t *rw) |
fb1c8f93 | 324 | { |
144b9c13 | 325 | __asm__ __volatile__("# write_unlock\n\t" |
f10e2e5b | 326 | PPC_RELEASE_BARRIER: : :"memory"); |
fb1c8f93 IM |
327 | rw->lock = 0; |
328 | } | |
329 | ||
e5931943 TG |
330 | #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) |
331 | #define arch_write_lock_flags(lock, flags) arch_write_lock(lock) | |
f5f7eac4 | 332 | |
0199c4e6 TG |
333 | #define arch_spin_relax(lock) __spin_yield(lock) |
334 | #define arch_read_relax(lock) __rw_yield(lock) | |
335 | #define arch_write_relax(lock) __rw_yield(lock) | |
ef6edc97 | 336 | |
88ced031 | 337 | #endif /* __KERNEL__ */ |
1da177e4 | 338 | #endif /* __ASM_SPINLOCK_H */ |