spinlock.h 6.16 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2
#ifndef __ASM_SPINLOCK_H
#define __ASM_SPINLOCK_H
3
#ifdef __KERNEL__
Linus Torvalds's avatar
Linus Torvalds committed
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

/*
 * Simple spin lock operations.  
 *
 * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
 * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
 * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
 *	Rework to support virtual processors
 *
 * Type of int is used as a full 64b word is not necessary.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
Ingo Molnar's avatar
Ingo Molnar committed
19 20
 *
 * (the type definitions are in asm/spinlock_types.h)
Linus Torvalds's avatar
Linus Torvalds committed
21
 */
Paul Mackerras's avatar
Paul Mackerras committed
22
#ifdef CONFIG_PPC64
Linus Torvalds's avatar
Linus Torvalds committed
23 24
#include <asm/paca.h>
#include <asm/hvcall.h>
25
#include <asm/iseries/hv_call.h>
Paul Mackerras's avatar
Paul Mackerras committed
26 27 28
#endif
#include <asm/asm-compat.h>
#include <asm/synch.h>
Linus Torvalds's avatar
Linus Torvalds committed
29

Ingo Molnar's avatar
Ingo Molnar committed
30
#define __raw_spin_is_locked(x)		((x)->slock != 0)
Linus Torvalds's avatar
Linus Torvalds committed
31

Paul Mackerras's avatar
Paul Mackerras committed
32 33 34 35 36 37 38
#ifdef CONFIG_PPC64
/* use 0x800000yy when locked, where yy == CPU number */
#define LOCK_TOKEN	(*(u32 *)(&get_paca()->lock_token))
#else
#define LOCK_TOKEN	1
#endif

Ingo Molnar's avatar
Ingo Molnar committed
39 40 41 42 43 44
/*
 * This returns the old value in the lock, so we succeeded
 * in getting the lock if the return value is 0.
 */
static __inline__ unsigned long __spin_trylock(raw_spinlock_t *lock)
{
Paul Mackerras's avatar
Paul Mackerras committed
45
	unsigned long tmp, token;
Linus Torvalds's avatar
Linus Torvalds committed
46

Paul Mackerras's avatar
Paul Mackerras committed
47
	token = LOCK_TOKEN;
Ingo Molnar's avatar
Ingo Molnar committed
48
	__asm__ __volatile__(
49
"1:	lwarx		%0,0,%2\n\
Ingo Molnar's avatar
Ingo Molnar committed
50 51 52 53 54
	cmpwi		0,%0,0\n\
	bne-		2f\n\
	stwcx.		%1,0,%2\n\
	bne-		1b\n\
	isync\n\
Paul Mackerras's avatar
Paul Mackerras committed
55 56
2:"	: "=&r" (tmp)
	: "r" (token), "r" (&lock->slock)
Ingo Molnar's avatar
Ingo Molnar committed
57
	: "cr0", "memory");
Linus Torvalds's avatar
Linus Torvalds committed
58

Ingo Molnar's avatar
Ingo Molnar committed
59 60
	return tmp;
}
Linus Torvalds's avatar
Linus Torvalds committed
61

Ingo Molnar's avatar
Ingo Molnar committed
62
static int __inline__ __raw_spin_trylock(raw_spinlock_t *lock)
Linus Torvalds's avatar
Linus Torvalds committed
63
{
Ingo Molnar's avatar
Ingo Molnar committed
64
	return __spin_trylock(lock) == 0;
Linus Torvalds's avatar
Linus Torvalds committed
65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82
}

/*
 * On a system with shared processors (that is, where a physical
 * processor is multiplexed between several virtual processors),
 * there is no point spinning on a lock if the holder of the lock
 * isn't currently scheduled on a physical processor.  Instead
 * we detect this situation and ask the hypervisor to give the
 * rest of our timeslice to the lock holder.
 *
 * So that we can tell which virtual processor is holding a lock,
 * we put 0x80000000 | smp_processor_id() in the lock when it is
 * held.  Conveniently, we have a word in the paca that holds this
 * value.
 */

#if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
/* We only yield to the hypervisor if we are in shared processor mode */
83
#define SHARED_PROCESSOR (get_lppaca()->shared_proc)
Ingo Molnar's avatar
Ingo Molnar committed
84 85
extern void __spin_yield(raw_spinlock_t *lock);
extern void __rw_yield(raw_rwlock_t *lock);
Linus Torvalds's avatar
Linus Torvalds committed
86 87 88 89 90 91
#else /* SPLPAR || ISERIES */
#define __spin_yield(x)	barrier()
#define __rw_yield(x)	barrier()
#define SHARED_PROCESSOR	0
#endif

Ingo Molnar's avatar
Ingo Molnar committed
92
static void __inline__ __raw_spin_lock(raw_spinlock_t *lock)
Linus Torvalds's avatar
Linus Torvalds committed
93 94 95 96 97 98 99 100
{
	while (1) {
		if (likely(__spin_trylock(lock) == 0))
			break;
		do {
			HMT_low();
			if (SHARED_PROCESSOR)
				__spin_yield(lock);
Ingo Molnar's avatar
Ingo Molnar committed
101
		} while (unlikely(lock->slock != 0));
Linus Torvalds's avatar
Linus Torvalds committed
102 103 104 105
		HMT_medium();
	}
}

Ingo Molnar's avatar
Ingo Molnar committed
106
static void __inline__ __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
Linus Torvalds's avatar
Linus Torvalds committed
107 108 109 110 111 112 113 114 115 116 117 118
{
	unsigned long flags_dis;

	while (1) {
		if (likely(__spin_trylock(lock) == 0))
			break;
		local_save_flags(flags_dis);
		local_irq_restore(flags);
		do {
			HMT_low();
			if (SHARED_PROCESSOR)
				__spin_yield(lock);
Ingo Molnar's avatar
Ingo Molnar committed
119
		} while (unlikely(lock->slock != 0));
Linus Torvalds's avatar
Linus Torvalds committed
120 121 122 123 124
		HMT_medium();
		local_irq_restore(flags_dis);
	}
}

Ingo Molnar's avatar
Ingo Molnar committed
125 126
static __inline__ void __raw_spin_unlock(raw_spinlock_t *lock)
{
127 128
	__asm__ __volatile__("# __raw_spin_unlock\n\t"
				LWSYNC_ON_SMP: : :"memory");
Ingo Molnar's avatar
Ingo Molnar committed
129 130 131
	lock->slock = 0;
}

Paul Mackerras's avatar
Paul Mackerras committed
132
#ifdef CONFIG_PPC64
Ingo Molnar's avatar
Ingo Molnar committed
133
extern void __raw_spin_unlock_wait(raw_spinlock_t *lock);
Paul Mackerras's avatar
Paul Mackerras committed
134 135 136 137
#else
#define __raw_spin_unlock_wait(lock) \
	do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
#endif
Ingo Molnar's avatar
Ingo Molnar committed
138

Linus Torvalds's avatar
Linus Torvalds committed
139 140 141 142 143 144 145 146 147 148 149
/*
 * 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.
 */

Ingo Molnar's avatar
Ingo Molnar committed
150 151
#define __raw_read_can_lock(rw)		((rw)->lock >= 0)
#define __raw_write_can_lock(rw)	(!(rw)->lock)
Linus Torvalds's avatar
Linus Torvalds committed
152

Paul Mackerras's avatar
Paul Mackerras committed
153 154 155 156 157 158 159 160
#ifdef CONFIG_PPC64
#define __DO_SIGN_EXTEND	"extsw	%0,%0\n"
#define WRLOCK_TOKEN		LOCK_TOKEN	/* it's negative */
#else
#define __DO_SIGN_EXTEND
#define WRLOCK_TOKEN		(-1)
#endif

Linus Torvalds's avatar
Linus Torvalds committed
161 162 163 164
/*
 * This returns the old value in the lock + 1,
 * so we got a read lock if the return value is > 0.
 */
Ingo Molnar's avatar
Ingo Molnar committed
165
static long __inline__ __read_trylock(raw_rwlock_t *rw)
Linus Torvalds's avatar
Linus Torvalds committed
166 167 168 169
{
	long tmp;

	__asm__ __volatile__(
170
"1:	lwarx		%0,0,%1\n"
Paul Mackerras's avatar
Paul Mackerras committed
171 172 173 174 175
	__DO_SIGN_EXTEND
"	addic.		%0,%0,1\n\
	ble-		2f\n"
	PPC405_ERR77(0,%1)
"	stwcx.		%0,0,%1\n\
Linus Torvalds's avatar
Linus Torvalds committed
176 177 178 179 180 181 182 183 184 185 186 187 188
	bne-		1b\n\
	isync\n\
2:"	: "=&r" (tmp)
	: "r" (&rw->lock)
	: "cr0", "xer", "memory");

	return tmp;
}

/*
 * This returns the old value in the lock,
 * so we got the write lock if the return value is 0.
 */
Ingo Molnar's avatar
Ingo Molnar committed
189
static __inline__ long __write_trylock(raw_rwlock_t *rw)
Linus Torvalds's avatar
Linus Torvalds committed
190
{
Paul Mackerras's avatar
Paul Mackerras committed
191
	long tmp, token;
Linus Torvalds's avatar
Linus Torvalds committed
192

Paul Mackerras's avatar
Paul Mackerras committed
193
	token = WRLOCK_TOKEN;
Linus Torvalds's avatar
Linus Torvalds committed
194
	__asm__ __volatile__(
195
"1:	lwarx		%0,0,%2\n\
Linus Torvalds's avatar
Linus Torvalds committed
196
	cmpwi		0,%0,0\n\
Paul Mackerras's avatar
Paul Mackerras committed
197 198 199
	bne-		2f\n"
	PPC405_ERR77(0,%1)
"	stwcx.		%1,0,%2\n\
Linus Torvalds's avatar
Linus Torvalds committed
200 201
	bne-		1b\n\
	isync\n\
Paul Mackerras's avatar
Paul Mackerras committed
202 203
2:"	: "=&r" (tmp)
	: "r" (token), "r" (&rw->lock)
Linus Torvalds's avatar
Linus Torvalds committed
204 205 206 207 208
	: "cr0", "memory");

	return tmp;
}

Ingo Molnar's avatar
Ingo Molnar committed
209
static void __inline__ __raw_read_lock(raw_rwlock_t *rw)
Linus Torvalds's avatar
Linus Torvalds committed
210
{
Ingo Molnar's avatar
Ingo Molnar committed
211 212 213 214 215 216 217 218 219 220
	while (1) {
		if (likely(__read_trylock(rw) > 0))
			break;
		do {
			HMT_low();
			if (SHARED_PROCESSOR)
				__rw_yield(rw);
		} while (unlikely(rw->lock < 0));
		HMT_medium();
	}
Linus Torvalds's avatar
Linus Torvalds committed
221 222
}

Ingo Molnar's avatar
Ingo Molnar committed
223
static void __inline__ __raw_write_lock(raw_rwlock_t *rw)
Linus Torvalds's avatar
Linus Torvalds committed
224 225 226 227 228 229 230 231
{
	while (1) {
		if (likely(__write_trylock(rw) == 0))
			break;
		do {
			HMT_low();
			if (SHARED_PROCESSOR)
				__rw_yield(rw);
232
		} while (unlikely(rw->lock != 0));
Linus Torvalds's avatar
Linus Torvalds committed
233 234 235 236
		HMT_medium();
	}
}

Ingo Molnar's avatar
Ingo Molnar committed
237 238 239 240 241 242 243 244 245 246 247 248 249 250 251
static int __inline__ __raw_read_trylock(raw_rwlock_t *rw)
{
	return __read_trylock(rw) > 0;
}

static int __inline__ __raw_write_trylock(raw_rwlock_t *rw)
{
	return __write_trylock(rw) == 0;
}

static void __inline__ __raw_read_unlock(raw_rwlock_t *rw)
{
	long tmp;

	__asm__ __volatile__(
252 253 254
	"# read_unlock\n\t"
	LWSYNC_ON_SMP
"1:	lwarx		%0,0,%1\n\
Paul Mackerras's avatar
Paul Mackerras committed
255 256 257
	addic		%0,%0,-1\n"
	PPC405_ERR77(0,%1)
"	stwcx.		%0,0,%1\n\
Ingo Molnar's avatar
Ingo Molnar committed
258 259 260 261 262 263 264 265
	bne-		1b"
	: "=&r"(tmp)
	: "r"(&rw->lock)
	: "cr0", "memory");
}

static __inline__ void __raw_write_unlock(raw_rwlock_t *rw)
{
266 267
	__asm__ __volatile__("# write_unlock\n\t"
				LWSYNC_ON_SMP: : :"memory");
Ingo Molnar's avatar
Ingo Molnar committed
268 269 270
	rw->lock = 0;
}

271
#endif /* __KERNEL__ */
Linus Torvalds's avatar
Linus Torvalds committed
272
#endif /* __ASM_SPINLOCK_H */