1 #ifndef __ASM_SPINLOCK_H
2 #define __ASM_SPINLOCK_H
6 * Simple spin lock operations.
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
13 * Type of int is used as a full 64b word is not necessary.
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.
20 * (the type definitions are in asm/spinlock_types.h)
22 #include <linux/jump_label.h>
23 #include <linux/irqflags.h>
26 #include <asm/hvcall.h>
28 #include <asm/synch.h>
29 #include <asm/ppc-opcode.h>
30 #include <asm/asm-405.h>
33 /* use 0x800000yy when locked, where yy == CPU number */
35 #define LOCK_TOKEN (*(u32 *)(&get_paca()->lock_token))
37 #define LOCK_TOKEN (*(u32 *)(&get_paca()->paca_index))
43 #if defined(CONFIG_PPC64) && defined(CONFIG_SMP)
44 #define CLEAR_IO_SYNC (get_paca()->io_sync = 0)
45 #define SYNC_IO do { \
46 if (unlikely(get_paca()->io_sync)) { \
48 get_paca()->io_sync = 0; \
56 #ifdef CONFIG_PPC_PSERIES
57 DECLARE_STATIC_KEY_FALSE(shared_processor);
59 #define vcpu_is_preempted vcpu_is_preempted
60 static inline bool vcpu_is_preempted(int cpu)
62 if (!static_branch_unlikely(&shared_processor))
64 return !!(be32_to_cpu(lppaca_of(cpu).yield_count) & 1);
68 static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock)
70 return lock.slock == 0;
73 static inline int arch_spin_is_locked(arch_spinlock_t *lock)
76 return !arch_spin_value_unlocked(*lock);
80 * This returns the old value in the lock, so we succeeded
81 * in getting the lock if the return value is 0.
83 static inline unsigned long __arch_spin_trylock(arch_spinlock_t *lock)
85 unsigned long tmp, token;
89 "1: " PPC_LWARX(%0,0,%2,1) "\n\
97 : "r" (token), "r" (&lock->slock)
103 static inline int arch_spin_trylock(arch_spinlock_t *lock)
106 return __arch_spin_trylock(lock) == 0;
110 * On a system with shared processors (that is, where a physical
111 * processor is multiplexed between several virtual processors),
112 * there is no point spinning on a lock if the holder of the lock
113 * isn't currently scheduled on a physical processor. Instead
114 * we detect this situation and ask the hypervisor to give the
115 * rest of our timeslice to the lock holder.
117 * So that we can tell which virtual processor is holding a lock,
118 * we put 0x80000000 | smp_processor_id() in the lock when it is
119 * held. Conveniently, we have a word in the paca that holds this
123 #if defined(CONFIG_PPC_SPLPAR)
124 /* We only yield to the hypervisor if we are in shared processor mode */
125 #define SHARED_PROCESSOR (lppaca_shared_proc(local_paca->lppaca_ptr))
126 extern void __spin_yield(arch_spinlock_t *lock);
127 extern void __rw_yield(arch_rwlock_t *lock);
129 #define __spin_yield(x) barrier()
130 #define __rw_yield(x) barrier()
131 #define SHARED_PROCESSOR 0
134 static inline void arch_spin_lock(arch_spinlock_t *lock)
138 if (likely(__arch_spin_trylock(lock) == 0))
142 if (SHARED_PROCESSOR)
144 } while (unlikely(lock->slock != 0));
150 void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
152 unsigned long flags_dis;
156 if (likely(__arch_spin_trylock(lock) == 0))
158 local_save_flags(flags_dis);
159 local_irq_restore(flags);
162 if (SHARED_PROCESSOR)
164 } while (unlikely(lock->slock != 0));
166 local_irq_restore(flags_dis);
169 #define arch_spin_lock_flags arch_spin_lock_flags
171 static inline void arch_spin_unlock(arch_spinlock_t *lock)
174 __asm__ __volatile__("# arch_spin_unlock\n\t"
175 PPC_RELEASE_BARRIER: : :"memory");
180 * Read-write spinlocks, allowing multiple readers
181 * but only one writer.
183 * NOTE! it is quite common to have readers in interrupts
184 * but no interrupt writers. For those circumstances we
185 * can "mix" irq-safe locks - any writer needs to get a
186 * irq-safe write-lock, but readers can get non-irqsafe
191 #define __DO_SIGN_EXTEND "extsw %0,%0\n"
192 #define WRLOCK_TOKEN LOCK_TOKEN /* it's negative */
194 #define __DO_SIGN_EXTEND
195 #define WRLOCK_TOKEN (-1)
199 * This returns the old value in the lock + 1,
200 * so we got a read lock if the return value is > 0.
202 static inline long __arch_read_trylock(arch_rwlock_t *rw)
206 __asm__ __volatile__(
207 "1: " PPC_LWARX(%0,0,%1,1) "\n"
217 : "cr0", "xer", "memory");
223 * This returns the old value in the lock,
224 * so we got the write lock if the return value is 0.
226 static inline long __arch_write_trylock(arch_rwlock_t *rw)
230 token = WRLOCK_TOKEN;
231 __asm__ __volatile__(
232 "1: " PPC_LWARX(%0,0,%2,1) "\n\
240 : "r" (token), "r" (&rw->lock)
246 static inline void arch_read_lock(arch_rwlock_t *rw)
249 if (likely(__arch_read_trylock(rw) > 0))
253 if (SHARED_PROCESSOR)
255 } while (unlikely(rw->lock < 0));
260 static inline void arch_write_lock(arch_rwlock_t *rw)
263 if (likely(__arch_write_trylock(rw) == 0))
267 if (SHARED_PROCESSOR)
269 } while (unlikely(rw->lock != 0));
274 static inline int arch_read_trylock(arch_rwlock_t *rw)
276 return __arch_read_trylock(rw) > 0;
279 static inline int arch_write_trylock(arch_rwlock_t *rw)
281 return __arch_write_trylock(rw) == 0;
284 static inline void arch_read_unlock(arch_rwlock_t *rw)
288 __asm__ __volatile__(
298 : "cr0", "xer", "memory");
301 static inline void arch_write_unlock(arch_rwlock_t *rw)
303 __asm__ __volatile__("# write_unlock\n\t"
304 PPC_RELEASE_BARRIER: : :"memory");
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)
312 /* See include/linux/spinlock.h */
313 #define smp_mb__after_spinlock() smp_mb()
315 #endif /* __KERNEL__ */
316 #endif /* __ASM_SPINLOCK_H */