1b8b572e1SStephen Rothwell #ifndef __ASM_SPINLOCK_H 2b8b572e1SStephen Rothwell #define __ASM_SPINLOCK_H 3b8b572e1SStephen Rothwell #ifdef __KERNEL__ 4b8b572e1SStephen Rothwell 5b8b572e1SStephen Rothwell /* 6b8b572e1SStephen Rothwell * Simple spin lock operations. 7b8b572e1SStephen Rothwell * 8b8b572e1SStephen Rothwell * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM 9b8b572e1SStephen Rothwell * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM 10b8b572e1SStephen Rothwell * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM 11b8b572e1SStephen Rothwell * Rework to support virtual processors 12b8b572e1SStephen Rothwell * 13b8b572e1SStephen Rothwell * Type of int is used as a full 64b word is not necessary. 14b8b572e1SStephen Rothwell * 15b8b572e1SStephen Rothwell * This program is free software; you can redistribute it and/or 16b8b572e1SStephen Rothwell * modify it under the terms of the GNU General Public License 17b8b572e1SStephen Rothwell * as published by the Free Software Foundation; either version 18b8b572e1SStephen Rothwell * 2 of the License, or (at your option) any later version. 19b8b572e1SStephen Rothwell * 20b8b572e1SStephen Rothwell * (the type definitions are in asm/spinlock_types.h) 21b8b572e1SStephen Rothwell */ 22b8b572e1SStephen Rothwell #include <linux/irqflags.h> 23b8b572e1SStephen Rothwell #ifdef CONFIG_PPC64 24b8b572e1SStephen Rothwell #include <asm/paca.h> 25b8b572e1SStephen Rothwell #include <asm/hvcall.h> 26b8b572e1SStephen Rothwell #endif 27b8b572e1SStephen Rothwell #include <asm/asm-compat.h> 28b8b572e1SStephen Rothwell #include <asm/synch.h> 294e14a4d1SAnton Blanchard #include <asm/ppc-opcode.h> 30b8b572e1SStephen Rothwell 31b8b572e1SStephen Rothwell #ifdef CONFIG_PPC64 32b8b572e1SStephen Rothwell /* use 0x800000yy when locked, where yy == CPU number */ 3354bb7f4bSAnton Blanchard #ifdef __BIG_ENDIAN__ 34b8b572e1SStephen Rothwell #define LOCK_TOKEN (*(u32 *)(&get_paca()->lock_token)) 35b8b572e1SStephen Rothwell #else 3654bb7f4bSAnton Blanchard #define LOCK_TOKEN (*(u32 *)(&get_paca()->paca_index)) 3754bb7f4bSAnton Blanchard #endif 3854bb7f4bSAnton Blanchard #else 39b8b572e1SStephen Rothwell #define LOCK_TOKEN 1 40b8b572e1SStephen Rothwell #endif 41b8b572e1SStephen Rothwell 42b8b572e1SStephen Rothwell #if defined(CONFIG_PPC64) && defined(CONFIG_SMP) 43b8b572e1SStephen Rothwell #define CLEAR_IO_SYNC (get_paca()->io_sync = 0) 44b8b572e1SStephen Rothwell #define SYNC_IO do { \ 45b8b572e1SStephen Rothwell if (unlikely(get_paca()->io_sync)) { \ 46b8b572e1SStephen Rothwell mb(); \ 47b8b572e1SStephen Rothwell get_paca()->io_sync = 0; \ 48b8b572e1SStephen Rothwell } \ 49b8b572e1SStephen Rothwell } while (0) 50b8b572e1SStephen Rothwell #else 51b8b572e1SStephen Rothwell #define CLEAR_IO_SYNC 52b8b572e1SStephen Rothwell #define SYNC_IO 53b8b572e1SStephen Rothwell #endif 54b8b572e1SStephen Rothwell 553405d230SMichael Ellerman static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock) 563405d230SMichael Ellerman { 573405d230SMichael Ellerman return lock.slock == 0; 583405d230SMichael Ellerman } 593405d230SMichael Ellerman 607179ba52SMichael Ellerman static inline int arch_spin_is_locked(arch_spinlock_t *lock) 617179ba52SMichael Ellerman { 6251d7d520SMichael Ellerman smp_mb(); 637179ba52SMichael Ellerman return !arch_spin_value_unlocked(*lock); 647179ba52SMichael Ellerman } 657179ba52SMichael Ellerman 66b8b572e1SStephen Rothwell /* 67b8b572e1SStephen Rothwell * This returns the old value in the lock, so we succeeded 68b8b572e1SStephen Rothwell * in getting the lock if the return value is 0. 69b8b572e1SStephen Rothwell */ 700199c4e6SThomas Gleixner static inline unsigned long __arch_spin_trylock(arch_spinlock_t *lock) 71b8b572e1SStephen Rothwell { 72b8b572e1SStephen Rothwell unsigned long tmp, token; 73b8b572e1SStephen Rothwell 74b8b572e1SStephen Rothwell token = LOCK_TOKEN; 75b8b572e1SStephen Rothwell __asm__ __volatile__( 764e14a4d1SAnton Blanchard "1: " PPC_LWARX(%0,0,%2,1) "\n\ 77b8b572e1SStephen Rothwell cmpwi 0,%0,0\n\ 78b8b572e1SStephen Rothwell bne- 2f\n\ 79b8b572e1SStephen Rothwell stwcx. %1,0,%2\n\ 80f10e2e5bSAnton Blanchard bne- 1b\n" 81f10e2e5bSAnton Blanchard PPC_ACQUIRE_BARRIER 82f10e2e5bSAnton Blanchard "2:" 83f10e2e5bSAnton Blanchard : "=&r" (tmp) 84b8b572e1SStephen Rothwell : "r" (token), "r" (&lock->slock) 85b8b572e1SStephen Rothwell : "cr0", "memory"); 86b8b572e1SStephen Rothwell 87b8b572e1SStephen Rothwell return tmp; 88b8b572e1SStephen Rothwell } 89b8b572e1SStephen Rothwell 900199c4e6SThomas Gleixner static inline int arch_spin_trylock(arch_spinlock_t *lock) 91b8b572e1SStephen Rothwell { 92b8b572e1SStephen Rothwell CLEAR_IO_SYNC; 930199c4e6SThomas Gleixner return __arch_spin_trylock(lock) == 0; 94b8b572e1SStephen Rothwell } 95b8b572e1SStephen Rothwell 96b8b572e1SStephen Rothwell /* 97b8b572e1SStephen Rothwell * On a system with shared processors (that is, where a physical 98b8b572e1SStephen Rothwell * processor is multiplexed between several virtual processors), 99b8b572e1SStephen Rothwell * there is no point spinning on a lock if the holder of the lock 100b8b572e1SStephen Rothwell * isn't currently scheduled on a physical processor. Instead 101b8b572e1SStephen Rothwell * we detect this situation and ask the hypervisor to give the 102b8b572e1SStephen Rothwell * rest of our timeslice to the lock holder. 103b8b572e1SStephen Rothwell * 104b8b572e1SStephen Rothwell * So that we can tell which virtual processor is holding a lock, 105b8b572e1SStephen Rothwell * we put 0x80000000 | smp_processor_id() in the lock when it is 106b8b572e1SStephen Rothwell * held. Conveniently, we have a word in the paca that holds this 107b8b572e1SStephen Rothwell * value. 108b8b572e1SStephen Rothwell */ 109b8b572e1SStephen Rothwell 1101b041885SStephen Rothwell #if defined(CONFIG_PPC_SPLPAR) 111b8b572e1SStephen Rothwell /* We only yield to the hypervisor if we are in shared processor mode */ 112f13c13a0SAnton Blanchard #define SHARED_PROCESSOR (lppaca_shared_proc(local_paca->lppaca_ptr)) 113445c8951SThomas Gleixner extern void __spin_yield(arch_spinlock_t *lock); 114fb3a6bbcSThomas Gleixner extern void __rw_yield(arch_rwlock_t *lock); 1151b041885SStephen Rothwell #else /* SPLPAR */ 116b8b572e1SStephen Rothwell #define __spin_yield(x) barrier() 117b8b572e1SStephen Rothwell #define __rw_yield(x) barrier() 118b8b572e1SStephen Rothwell #define SHARED_PROCESSOR 0 119b8b572e1SStephen Rothwell #endif 120b8b572e1SStephen Rothwell 1210199c4e6SThomas Gleixner static inline void arch_spin_lock(arch_spinlock_t *lock) 122b8b572e1SStephen Rothwell { 123b8b572e1SStephen Rothwell CLEAR_IO_SYNC; 124b8b572e1SStephen Rothwell while (1) { 1250199c4e6SThomas Gleixner if (likely(__arch_spin_trylock(lock) == 0)) 126b8b572e1SStephen Rothwell break; 127b8b572e1SStephen Rothwell do { 128b8b572e1SStephen Rothwell HMT_low(); 129b8b572e1SStephen Rothwell if (SHARED_PROCESSOR) 130b8b572e1SStephen Rothwell __spin_yield(lock); 131b8b572e1SStephen Rothwell } while (unlikely(lock->slock != 0)); 132b8b572e1SStephen Rothwell HMT_medium(); 133b8b572e1SStephen Rothwell } 134b8b572e1SStephen Rothwell } 135b8b572e1SStephen Rothwell 136b8b572e1SStephen Rothwell static inline 1370199c4e6SThomas Gleixner void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags) 138b8b572e1SStephen Rothwell { 139b8b572e1SStephen Rothwell unsigned long flags_dis; 140b8b572e1SStephen Rothwell 141b8b572e1SStephen Rothwell CLEAR_IO_SYNC; 142b8b572e1SStephen Rothwell while (1) { 1430199c4e6SThomas Gleixner if (likely(__arch_spin_trylock(lock) == 0)) 144b8b572e1SStephen Rothwell break; 145b8b572e1SStephen Rothwell local_save_flags(flags_dis); 146b8b572e1SStephen Rothwell local_irq_restore(flags); 147b8b572e1SStephen Rothwell do { 148b8b572e1SStephen Rothwell HMT_low(); 149b8b572e1SStephen Rothwell if (SHARED_PROCESSOR) 150b8b572e1SStephen Rothwell __spin_yield(lock); 151b8b572e1SStephen Rothwell } while (unlikely(lock->slock != 0)); 152b8b572e1SStephen Rothwell HMT_medium(); 153b8b572e1SStephen Rothwell local_irq_restore(flags_dis); 154b8b572e1SStephen Rothwell } 155b8b572e1SStephen Rothwell } 156b8b572e1SStephen Rothwell 1570199c4e6SThomas Gleixner static inline void arch_spin_unlock(arch_spinlock_t *lock) 158b8b572e1SStephen Rothwell { 159b8b572e1SStephen Rothwell SYNC_IO; 1600199c4e6SThomas Gleixner __asm__ __volatile__("# arch_spin_unlock\n\t" 161f10e2e5bSAnton Blanchard PPC_RELEASE_BARRIER: : :"memory"); 162b8b572e1SStephen Rothwell lock->slock = 0; 163b8b572e1SStephen Rothwell } 164b8b572e1SStephen Rothwell 1656262db7cSBoqun Feng static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) 1666262db7cSBoqun Feng { 1676262db7cSBoqun Feng arch_spinlock_t lock_val; 1686262db7cSBoqun Feng 1696262db7cSBoqun Feng smp_mb(); 1706262db7cSBoqun Feng 1716262db7cSBoqun Feng /* 1726262db7cSBoqun Feng * Atomically load and store back the lock value (unchanged). This 1736262db7cSBoqun Feng * ensures that our observation of the lock value is ordered with 1746262db7cSBoqun Feng * respect to other lock operations. 1756262db7cSBoqun Feng */ 1766262db7cSBoqun Feng __asm__ __volatile__( 1776262db7cSBoqun Feng "1: " PPC_LWARX(%0, 0, %2, 0) "\n" 1786262db7cSBoqun Feng " stwcx. %0, 0, %2\n" 1796262db7cSBoqun Feng " bne- 1b\n" 1806262db7cSBoqun Feng : "=&r" (lock_val), "+m" (*lock) 1816262db7cSBoqun Feng : "r" (lock) 1826262db7cSBoqun Feng : "cr0", "xer"); 1836262db7cSBoqun Feng 1846262db7cSBoqun Feng if (arch_spin_value_unlocked(lock_val)) 1856262db7cSBoqun Feng goto out; 1866262db7cSBoqun Feng 1876262db7cSBoqun Feng while (lock->slock) { 1886262db7cSBoqun Feng HMT_low(); 1896262db7cSBoqun Feng if (SHARED_PROCESSOR) 1906262db7cSBoqun Feng __spin_yield(lock); 1916262db7cSBoqun Feng } 1926262db7cSBoqun Feng HMT_medium(); 1936262db7cSBoqun Feng 1946262db7cSBoqun Feng out: 1956262db7cSBoqun Feng smp_mb(); 1966262db7cSBoqun Feng } 197b8b572e1SStephen Rothwell 198b8b572e1SStephen Rothwell /* 199b8b572e1SStephen Rothwell * Read-write spinlocks, allowing multiple readers 200b8b572e1SStephen Rothwell * but only one writer. 201b8b572e1SStephen Rothwell * 202b8b572e1SStephen Rothwell * NOTE! it is quite common to have readers in interrupts 203b8b572e1SStephen Rothwell * but no interrupt writers. For those circumstances we 204b8b572e1SStephen Rothwell * can "mix" irq-safe locks - any writer needs to get a 205b8b572e1SStephen Rothwell * irq-safe write-lock, but readers can get non-irqsafe 206b8b572e1SStephen Rothwell * read-locks. 207b8b572e1SStephen Rothwell */ 208b8b572e1SStephen Rothwell 209e5931943SThomas Gleixner #define arch_read_can_lock(rw) ((rw)->lock >= 0) 210e5931943SThomas Gleixner #define arch_write_can_lock(rw) (!(rw)->lock) 211b8b572e1SStephen Rothwell 212b8b572e1SStephen Rothwell #ifdef CONFIG_PPC64 213b8b572e1SStephen Rothwell #define __DO_SIGN_EXTEND "extsw %0,%0\n" 214b8b572e1SStephen Rothwell #define WRLOCK_TOKEN LOCK_TOKEN /* it's negative */ 215b8b572e1SStephen Rothwell #else 216b8b572e1SStephen Rothwell #define __DO_SIGN_EXTEND 217b8b572e1SStephen Rothwell #define WRLOCK_TOKEN (-1) 218b8b572e1SStephen Rothwell #endif 219b8b572e1SStephen Rothwell 220b8b572e1SStephen Rothwell /* 221b8b572e1SStephen Rothwell * This returns the old value in the lock + 1, 222b8b572e1SStephen Rothwell * so we got a read lock if the return value is > 0. 223b8b572e1SStephen Rothwell */ 224e5931943SThomas Gleixner static inline long __arch_read_trylock(arch_rwlock_t *rw) 225b8b572e1SStephen Rothwell { 226b8b572e1SStephen Rothwell long tmp; 227b8b572e1SStephen Rothwell 228b8b572e1SStephen Rothwell __asm__ __volatile__( 2294e14a4d1SAnton Blanchard "1: " PPC_LWARX(%0,0,%1,1) "\n" 230b8b572e1SStephen Rothwell __DO_SIGN_EXTEND 231b8b572e1SStephen Rothwell " addic. %0,%0,1\n\ 232b8b572e1SStephen Rothwell ble- 2f\n" 233b8b572e1SStephen Rothwell PPC405_ERR77(0,%1) 234b8b572e1SStephen Rothwell " stwcx. %0,0,%1\n\ 235f10e2e5bSAnton Blanchard bne- 1b\n" 236f10e2e5bSAnton Blanchard PPC_ACQUIRE_BARRIER 237f10e2e5bSAnton Blanchard "2:" : "=&r" (tmp) 238b8b572e1SStephen Rothwell : "r" (&rw->lock) 239b8b572e1SStephen Rothwell : "cr0", "xer", "memory"); 240b8b572e1SStephen Rothwell 241b8b572e1SStephen Rothwell return tmp; 242b8b572e1SStephen Rothwell } 243b8b572e1SStephen Rothwell 244b8b572e1SStephen Rothwell /* 245b8b572e1SStephen Rothwell * This returns the old value in the lock, 246b8b572e1SStephen Rothwell * so we got the write lock if the return value is 0. 247b8b572e1SStephen Rothwell */ 248e5931943SThomas Gleixner static inline long __arch_write_trylock(arch_rwlock_t *rw) 249b8b572e1SStephen Rothwell { 250b8b572e1SStephen Rothwell long tmp, token; 251b8b572e1SStephen Rothwell 252b8b572e1SStephen Rothwell token = WRLOCK_TOKEN; 253b8b572e1SStephen Rothwell __asm__ __volatile__( 2544e14a4d1SAnton Blanchard "1: " PPC_LWARX(%0,0,%2,1) "\n\ 255b8b572e1SStephen Rothwell cmpwi 0,%0,0\n\ 256b8b572e1SStephen Rothwell bne- 2f\n" 257b8b572e1SStephen Rothwell PPC405_ERR77(0,%1) 258b8b572e1SStephen Rothwell " stwcx. %1,0,%2\n\ 259f10e2e5bSAnton Blanchard bne- 1b\n" 260f10e2e5bSAnton Blanchard PPC_ACQUIRE_BARRIER 261f10e2e5bSAnton Blanchard "2:" : "=&r" (tmp) 262b8b572e1SStephen Rothwell : "r" (token), "r" (&rw->lock) 263b8b572e1SStephen Rothwell : "cr0", "memory"); 264b8b572e1SStephen Rothwell 265b8b572e1SStephen Rothwell return tmp; 266b8b572e1SStephen Rothwell } 267b8b572e1SStephen Rothwell 268e5931943SThomas Gleixner static inline void arch_read_lock(arch_rwlock_t *rw) 269b8b572e1SStephen Rothwell { 270b8b572e1SStephen Rothwell while (1) { 271e5931943SThomas Gleixner if (likely(__arch_read_trylock(rw) > 0)) 272b8b572e1SStephen Rothwell break; 273b8b572e1SStephen Rothwell do { 274b8b572e1SStephen Rothwell HMT_low(); 275b8b572e1SStephen Rothwell if (SHARED_PROCESSOR) 276b8b572e1SStephen Rothwell __rw_yield(rw); 277b8b572e1SStephen Rothwell } while (unlikely(rw->lock < 0)); 278b8b572e1SStephen Rothwell HMT_medium(); 279b8b572e1SStephen Rothwell } 280b8b572e1SStephen Rothwell } 281b8b572e1SStephen Rothwell 282e5931943SThomas Gleixner static inline void arch_write_lock(arch_rwlock_t *rw) 283b8b572e1SStephen Rothwell { 284b8b572e1SStephen Rothwell while (1) { 285e5931943SThomas Gleixner if (likely(__arch_write_trylock(rw) == 0)) 286b8b572e1SStephen Rothwell break; 287b8b572e1SStephen Rothwell do { 288b8b572e1SStephen Rothwell HMT_low(); 289b8b572e1SStephen Rothwell if (SHARED_PROCESSOR) 290b8b572e1SStephen Rothwell __rw_yield(rw); 291b8b572e1SStephen Rothwell } while (unlikely(rw->lock != 0)); 292b8b572e1SStephen Rothwell HMT_medium(); 293b8b572e1SStephen Rothwell } 294b8b572e1SStephen Rothwell } 295b8b572e1SStephen Rothwell 296e5931943SThomas Gleixner static inline int arch_read_trylock(arch_rwlock_t *rw) 297b8b572e1SStephen Rothwell { 298e5931943SThomas Gleixner return __arch_read_trylock(rw) > 0; 299b8b572e1SStephen Rothwell } 300b8b572e1SStephen Rothwell 301e5931943SThomas Gleixner static inline int arch_write_trylock(arch_rwlock_t *rw) 302b8b572e1SStephen Rothwell { 303e5931943SThomas Gleixner return __arch_write_trylock(rw) == 0; 304b8b572e1SStephen Rothwell } 305b8b572e1SStephen Rothwell 306e5931943SThomas Gleixner static inline void arch_read_unlock(arch_rwlock_t *rw) 307b8b572e1SStephen Rothwell { 308b8b572e1SStephen Rothwell long tmp; 309b8b572e1SStephen Rothwell 310b8b572e1SStephen Rothwell __asm__ __volatile__( 311b8b572e1SStephen Rothwell "# read_unlock\n\t" 312f10e2e5bSAnton Blanchard PPC_RELEASE_BARRIER 313b8b572e1SStephen Rothwell "1: lwarx %0,0,%1\n\ 314b8b572e1SStephen Rothwell addic %0,%0,-1\n" 315b8b572e1SStephen Rothwell PPC405_ERR77(0,%1) 316b8b572e1SStephen Rothwell " stwcx. %0,0,%1\n\ 317b8b572e1SStephen Rothwell bne- 1b" 318b8b572e1SStephen Rothwell : "=&r"(tmp) 319b8b572e1SStephen Rothwell : "r"(&rw->lock) 320efc3624cSPaul Mackerras : "cr0", "xer", "memory"); 321b8b572e1SStephen Rothwell } 322b8b572e1SStephen Rothwell 323e5931943SThomas Gleixner static inline void arch_write_unlock(arch_rwlock_t *rw) 324b8b572e1SStephen Rothwell { 325b8b572e1SStephen Rothwell __asm__ __volatile__("# write_unlock\n\t" 326f10e2e5bSAnton Blanchard PPC_RELEASE_BARRIER: : :"memory"); 327b8b572e1SStephen Rothwell rw->lock = 0; 328b8b572e1SStephen Rothwell } 329b8b572e1SStephen Rothwell 330e5931943SThomas Gleixner #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) 331e5931943SThomas Gleixner #define arch_write_lock_flags(lock, flags) arch_write_lock(lock) 332f5f7eac4SRobin Holt 3330199c4e6SThomas Gleixner #define arch_spin_relax(lock) __spin_yield(lock) 3340199c4e6SThomas Gleixner #define arch_read_relax(lock) __rw_yield(lock) 3350199c4e6SThomas Gleixner #define arch_write_relax(lock) __rw_yield(lock) 336b8b572e1SStephen Rothwell 337b8b572e1SStephen Rothwell #endif /* __KERNEL__ */ 338b8b572e1SStephen Rothwell #endif /* __ASM_SPINLOCK_H */ 339