aboutsummaryrefslogtreecommitdiffstats
path: root/arch/ppc/lib/locks.c
blob: 694163d696d886244b6ea769ab8b19abed8b65a0 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
/*
 * Locks for smp ppc
 *
 * Written by Cort Dougan (cort@cs.nmt.edu)
 */

#include <linux/config.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <asm/ppc_asm.h>
#include <asm/smp.h>

#ifdef CONFIG_DEBUG_SPINLOCK

#undef INIT_STUCK
#define INIT_STUCK 200000000 /*0xffffffff*/

/*
 * Try to acquire a spinlock.
 * Only does the stwcx. if the load returned 0 - the Programming
 * Environments Manual suggests not doing unnecessary stcwx.'s
 * since they may inhibit forward progress by other CPUs in getting
 * a lock.
 */
static inline unsigned long __spin_trylock(volatile unsigned long *lock)
{
	unsigned long ret;

	__asm__ __volatile__ ("\n\
1:	lwarx	%0,0,%1\n\
	cmpwi	0,%0,0\n\
	bne	2f\n"
	PPC405_ERR77(0,%1)
"	stwcx.	%2,0,%1\n\
	bne-	1b\n\
	isync\n\
2:"
	: "=&r"(ret)
	: "r"(lock), "r"(1)
	: "cr0", "memory");

	return ret;
}

void _raw_spin_lock(spinlock_t *lock)
{
	int cpu = smp_processor_id();
	unsigned int stuck = INIT_STUCK;
	while (__spin_trylock(&lock->lock)) {
		while ((unsigned volatile long)lock->lock != 0) {
			if (!--stuck) {
				printk("_spin_lock(%p) CPU#%d NIP %p"
				       " holder: cpu %ld pc %08lX\n",
				       lock, cpu, __builtin_return_address(0),
				       lock->owner_cpu,lock->owner_pc);
				stuck = INIT_STUCK;
				/* steal the lock */
				/*xchg_u32((void *)&lock->lock,0);*/
			}
		}
	}
	lock->owner_pc = (unsigned long)__builtin_return_address(0);
	lock->owner_cpu = cpu;
}
EXPORT_SYMBOL(_raw_spin_lock);

int _raw_spin_trylock(spinlock_t *lock)
{
	if (__spin_trylock(&lock->lock))
		return 0;
	lock->owner_cpu = smp_processor_id();
	lock->owner_pc = (unsigned long)__builtin_return_address(0);
	return 1;
}
EXPORT_SYMBOL(_raw_spin_trylock);

void _raw_spin_unlock(spinlock_t *lp)
{
  	if ( !lp->lock )
		printk("_spin_unlock(%p): no lock cpu %d curr PC %p %s/%d\n",
		       lp, smp_processor_id(), __builtin_return_address(0),
		       current->comm, current->pid);
	if ( lp->owner_cpu != smp_processor_id() )
		printk("_spin_unlock(%p): cpu %d trying clear of cpu %d pc %lx val %lx\n",
		      lp, smp_processor_id(), (int)lp->owner_cpu,
		      lp->owner_pc,lp->lock);
	lp->owner_pc = lp->owner_cpu = 0;
	wmb();
	lp->lock = 0;
}
EXPORT_SYMBOL(_raw_spin_unlock);

/*
 * For rwlocks, zero is unlocked, -1 is write-locked,
 * positive is read-locked.
 */
static __inline__ int __read_trylock(rwlock_t *rw)
{
	signed int tmp;

	__asm__ __volatile__(
"2:	lwarx	%0,0,%1		# __read_trylock\n\
	addic.	%0,%0,1\n\
	ble-	1f\n"
	PPC405_ERR77(0,%1)
"	stwcx.	%0,0,%1\n\
	bne-	2b\n\
	isync\n\
1:"
	: "=&r"(tmp)
	: "r"(&rw->lock)
	: "cr0", "memory");

	return tmp;
}

int _raw_read_trylock(rwlock_t *rw)
{
	return __read_trylock(rw) > 0;
}
EXPORT_SYMBOL(_raw_read_trylock);

void _raw_read_lock(rwlock_t *rw)
{
	unsigned int stuck;

	while (__read_trylock(rw) <= 0) {
		stuck = INIT_STUCK;
		while (!read_can_lock(rw)) {
			if (--stuck == 0) {
				printk("_read_lock(%p) CPU#%d lock %d\n",
				       rw, _smp_processor_id(), rw->lock);
				stuck = INIT_STUCK;
			}
		}
	}
}
EXPORT_SYMBOL(_raw_read_lock);

void _raw_read_unlock(rwlock_t *rw)
{
	if ( rw->lock == 0 )
		printk("_read_unlock(): %s/%d (nip %08lX) lock %d\n",
		       current->comm,current->pid,current->thread.regs->nip,
		      rw->lock);
	wmb();
	atomic_dec((atomic_t *) &(rw)->lock);
}
EXPORT_SYMBOL(_raw_read_unlock);

void _raw_write_lock(rwlock_t *rw)
{
	unsigned int stuck;

	while (cmpxchg(&rw->lock, 0, -1) != 0) {
		stuck = INIT_STUCK;
		while (!write_can_lock(rw)) {
			if (--stuck == 0) {
				printk("write_lock(%p) CPU#%d lock %d)\n",
				       rw, _smp_processor_id(), rw->lock);
				stuck = INIT_STUCK;
			}
		}
	}
	wmb();
}
EXPORT_SYMBOL(_raw_write_lock);

int _raw_write_trylock(rwlock_t *rw)
{
	if (cmpxchg(&rw->lock, 0, -1) != 0)
		return 0;
	wmb();
	return 1;
}
EXPORT_SYMBOL(_raw_write_trylock);

void _raw_write_unlock(rwlock_t *rw)
{
	if (rw->lock >= 0)
		printk("_write_lock(): %s/%d (nip %08lX) lock %d\n",
		      current->comm,current->pid,current->thread.regs->nip,
		      rw->lock);
	wmb();
	rw->lock = 0;
}
EXPORT_SYMBOL(_raw_write_unlock);

#endif