1 #ifndef __ASM_SPINLOCK_H 2 #define __ASM_SPINLOCK_H 3 #ifdef __KERNEL__ 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. 19 * 20 * (the type definitions are in asm/spinlock_types.h) 21 */ 22 #include <linux/irqflags.h> 23 #ifdef CONFIG_PPC64 24 #include <asm/paca.h> 25 #include <asm/hvcall.h> 26 #endif 27 #include <asm/asm-compat.h> 28 #include <asm/synch.h> 29 #include <asm/ppc-opcode.h> 30 31 #define smp_mb__after_unlock_lock() smp_mb() /* Full ordering for lock. */ 32 33 #ifdef CONFIG_PPC64 34 /* use 0x800000yy when locked, where yy == CPU number */ 35 #ifdef __BIG_ENDIAN__ 36 #define LOCK_TOKEN (*(u32 *)(&get_paca()->lock_token)) 37 #else 38 #define LOCK_TOKEN (*(u32 *)(&get_paca()->paca_index)) 39 #endif 40 #else 41 #define LOCK_TOKEN 1 42 #endif 43 44 #if defined(CONFIG_PPC64) && defined(CONFIG_SMP) 45 #define CLEAR_IO_SYNC (get_paca()->io_sync = 0) 46 #define SYNC_IO do { \ 47 if (unlikely(get_paca()->io_sync)) { \ 48 mb(); \ 49 get_paca()->io_sync = 0; \ 50 } \ 51 } while (0) 52 #else 53 #define CLEAR_IO_SYNC 54 #define SYNC_IO 55 #endif 56 57 static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock) 58 { 59 return lock.slock == 0; 60 } 61 62 static inline int arch_spin_is_locked(arch_spinlock_t *lock) 63 { 64 return !arch_spin_value_unlocked(*lock); 65 } 66 67 /* 68 * This returns the old value in the lock, so we succeeded 69 * in getting the lock if the return value is 0. 70 */ 71 static inline unsigned long __arch_spin_trylock(arch_spinlock_t *lock) 72 { 73 unsigned long tmp, token; 74 75 token = LOCK_TOKEN; 76 __asm__ __volatile__( 77 "1: " PPC_LWARX(%0,0,%2,1) "\n\ 78 cmpwi 0,%0,0\n\ 79 bne- 2f\n\ 80 stwcx. %1,0,%2\n\ 81 bne- 1b\n" 82 PPC_ACQUIRE_BARRIER 83 "2:" 84 : "=&r" (tmp) 85 : "r" (token), "r" (&lock->slock) 86 : "cr0", "memory"); 87 88 return tmp; 89 } 90 91 static inline int arch_spin_trylock(arch_spinlock_t *lock) 92 { 93 CLEAR_IO_SYNC; 94 return __arch_spin_trylock(lock) == 0; 95 } 96 97 /* 98 * On a system with shared processors (that is, where a physical 99 * processor is multiplexed between several virtual processors), 100 * there is no point spinning on a lock if the holder of the lock 101 * isn't currently scheduled on a physical processor. Instead 102 * we detect this situation and ask the hypervisor to give the 103 * rest of our timeslice to the lock holder. 104 * 105 * So that we can tell which virtual processor is holding a lock, 106 * we put 0x80000000 | smp_processor_id() in the lock when it is 107 * held. Conveniently, we have a word in the paca that holds this 108 * value. 109 */ 110 111 #if defined(CONFIG_PPC_SPLPAR) 112 /* We only yield to the hypervisor if we are in shared processor mode */ 113 #define SHARED_PROCESSOR (lppaca_shared_proc(local_paca->lppaca_ptr)) 114 extern void __spin_yield(arch_spinlock_t *lock); 115 extern void __rw_yield(arch_rwlock_t *lock); 116 #else /* SPLPAR */ 117 #define __spin_yield(x) barrier() 118 #define __rw_yield(x) barrier() 119 #define SHARED_PROCESSOR 0 120 #endif 121 122 static inline void arch_spin_lock(arch_spinlock_t *lock) 123 { 124 CLEAR_IO_SYNC; 125 while (1) { 126 if (likely(__arch_spin_trylock(lock) == 0)) 127 break; 128 do { 129 HMT_low(); 130 if (SHARED_PROCESSOR) 131 __spin_yield(lock); 132 } while (unlikely(lock->slock != 0)); 133 HMT_medium(); 134 } 135 } 136 137 static inline 138 void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags) 139 { 140 unsigned long flags_dis; 141 142 CLEAR_IO_SYNC; 143 while (1) { 144 if (likely(__arch_spin_trylock(lock) == 0)) 145 break; 146 local_save_flags(flags_dis); 147 local_irq_restore(flags); 148 do { 149 HMT_low(); 150 if (SHARED_PROCESSOR) 151 __spin_yield(lock); 152 } while (unlikely(lock->slock != 0)); 153 HMT_medium(); 154 local_irq_restore(flags_dis); 155 } 156 } 157 158 static inline void arch_spin_unlock(arch_spinlock_t *lock) 159 { 160 SYNC_IO; 161 __asm__ __volatile__("# arch_spin_unlock\n\t" 162 PPC_RELEASE_BARRIER: : :"memory"); 163 lock->slock = 0; 164 } 165 166 #ifdef CONFIG_PPC64 167 extern void arch_spin_unlock_wait(arch_spinlock_t *lock); 168 #else 169 #define arch_spin_unlock_wait(lock) \ 170 do { while (arch_spin_is_locked(lock)) cpu_relax(); } while (0) 171 #endif 172 173 /* 174 * Read-write spinlocks, allowing multiple readers 175 * but only one writer. 176 * 177 * NOTE! it is quite common to have readers in interrupts 178 * but no interrupt writers. For those circumstances we 179 * can "mix" irq-safe locks - any writer needs to get a 180 * irq-safe write-lock, but readers can get non-irqsafe 181 * read-locks. 182 */ 183 184 #define arch_read_can_lock(rw) ((rw)->lock >= 0) 185 #define arch_write_can_lock(rw) (!(rw)->lock) 186 187 #ifdef CONFIG_PPC64 188 #define __DO_SIGN_EXTEND "extsw %0,%0\n" 189 #define WRLOCK_TOKEN LOCK_TOKEN /* it's negative */ 190 #else 191 #define __DO_SIGN_EXTEND 192 #define WRLOCK_TOKEN (-1) 193 #endif 194 195 /* 196 * This returns the old value in the lock + 1, 197 * so we got a read lock if the return value is > 0. 198 */ 199 static inline long __arch_read_trylock(arch_rwlock_t *rw) 200 { 201 long tmp; 202 203 __asm__ __volatile__( 204 "1: " PPC_LWARX(%0,0,%1,1) "\n" 205 __DO_SIGN_EXTEND 206 " addic. %0,%0,1\n\ 207 ble- 2f\n" 208 PPC405_ERR77(0,%1) 209 " stwcx. %0,0,%1\n\ 210 bne- 1b\n" 211 PPC_ACQUIRE_BARRIER 212 "2:" : "=&r" (tmp) 213 : "r" (&rw->lock) 214 : "cr0", "xer", "memory"); 215 216 return tmp; 217 } 218 219 /* 220 * This returns the old value in the lock, 221 * so we got the write lock if the return value is 0. 222 */ 223 static inline long __arch_write_trylock(arch_rwlock_t *rw) 224 { 225 long tmp, token; 226 227 token = WRLOCK_TOKEN; 228 __asm__ __volatile__( 229 "1: " PPC_LWARX(%0,0,%2,1) "\n\ 230 cmpwi 0,%0,0\n\ 231 bne- 2f\n" 232 PPC405_ERR77(0,%1) 233 " stwcx. %1,0,%2\n\ 234 bne- 1b\n" 235 PPC_ACQUIRE_BARRIER 236 "2:" : "=&r" (tmp) 237 : "r" (token), "r" (&rw->lock) 238 : "cr0", "memory"); 239 240 return tmp; 241 } 242 243 static inline void arch_read_lock(arch_rwlock_t *rw) 244 { 245 while (1) { 246 if (likely(__arch_read_trylock(rw) > 0)) 247 break; 248 do { 249 HMT_low(); 250 if (SHARED_PROCESSOR) 251 __rw_yield(rw); 252 } while (unlikely(rw->lock < 0)); 253 HMT_medium(); 254 } 255 } 256 257 static inline void arch_write_lock(arch_rwlock_t *rw) 258 { 259 while (1) { 260 if (likely(__arch_write_trylock(rw) == 0)) 261 break; 262 do { 263 HMT_low(); 264 if (SHARED_PROCESSOR) 265 __rw_yield(rw); 266 } while (unlikely(rw->lock != 0)); 267 HMT_medium(); 268 } 269 } 270 271 static inline int arch_read_trylock(arch_rwlock_t *rw) 272 { 273 return __arch_read_trylock(rw) > 0; 274 } 275 276 static inline int arch_write_trylock(arch_rwlock_t *rw) 277 { 278 return __arch_write_trylock(rw) == 0; 279 } 280 281 static inline void arch_read_unlock(arch_rwlock_t *rw) 282 { 283 long tmp; 284 285 __asm__ __volatile__( 286 "# read_unlock\n\t" 287 PPC_RELEASE_BARRIER 288 "1: lwarx %0,0,%1\n\ 289 addic %0,%0,-1\n" 290 PPC405_ERR77(0,%1) 291 " stwcx. %0,0,%1\n\ 292 bne- 1b" 293 : "=&r"(tmp) 294 : "r"(&rw->lock) 295 : "cr0", "xer", "memory"); 296 } 297 298 static inline void arch_write_unlock(arch_rwlock_t *rw) 299 { 300 __asm__ __volatile__("# write_unlock\n\t" 301 PPC_RELEASE_BARRIER: : :"memory"); 302 rw->lock = 0; 303 } 304 305 #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) 306 #define arch_write_lock_flags(lock, flags) arch_write_lock(lock) 307 308 #define arch_spin_relax(lock) __spin_yield(lock) 309 #define arch_read_relax(lock) __rw_yield(lock) 310 #define arch_write_relax(lock) __rw_yield(lock) 311 312 #endif /* __KERNEL__ */ 313 #endif /* __ASM_SPINLOCK_H */ 314