1 /* $Id: debuglocks.c,v 1.9 2001/11/17 00:10:48 davem Exp $
2 * debuglocks.c: Debugging versions of SMP locking primitives.
4 * Copyright (C) 1998 David S. Miller (davem@redhat.com)
7 #include <linux/config.h>
8 #include <linux/kernel.h>
9 #include <linux/sched.h>
10 #include <linux/spinlock.h>
11 #include <asm/system.h>
15 #define GET_CALLER(PC) __asm__ __volatile__("mov %%i7, %0" : "=r" (PC))
17 static inline void show (char *str
, spinlock_t
*lock
, unsigned long caller
)
19 int cpu
= smp_processor_id();
21 printk("%s(%p) CPU#%d stuck at %08x, owner PC(%08x):CPU(%x)\n",
22 str
, lock
, cpu
, (unsigned int) caller
,
23 lock
->owner_pc
, lock
->owner_cpu
);
26 static inline void show_read (char *str
, rwlock_t
*lock
, unsigned long caller
)
28 int cpu
= smp_processor_id();
30 printk("%s(%p) CPU#%d stuck at %08x, writer PC(%08x):CPU(%x)\n",
31 str
, lock
, cpu
, (unsigned int) caller
,
32 lock
->writer_pc
, lock
->writer_cpu
);
35 static inline void show_write (char *str
, rwlock_t
*lock
, unsigned long caller
)
37 int cpu
= smp_processor_id();
40 printk("%s(%p) CPU#%d stuck at %08x\n",
41 str
, lock
, cpu
, (unsigned int) caller
);
42 printk("Writer: PC(%08x):CPU(%x)\n",
43 lock
->writer_pc
, lock
->writer_cpu
);
45 for (i
= 0; i
< NR_CPUS
; i
++)
46 if (lock
->reader_pc
[i
])
47 printk(" %d[%08x]", i
, lock
->reader_pc
[i
]);
52 #define INIT_STUCK 100000000
54 void _do_spin_lock(spinlock_t
*lock
, char *str
)
56 unsigned long caller
, val
;
57 int stuck
= INIT_STUCK
;
63 __asm__
__volatile__("ldstub [%1], %0"
67 membar("#StoreLoad | #StoreStore");
72 show(str
, lock
, caller
);
79 lock
->owner_pc
= ((unsigned int)caller
);
80 lock
->owner_cpu
= cpu
;
81 current
->thread
.smp_lock_count
++;
82 current
->thread
.smp_lock_pc
= ((unsigned int)caller
);
87 int _do_spin_trylock(spinlock_t
*lock
)
89 unsigned long val
, caller
;
93 __asm__
__volatile__("ldstub [%1], %0"
97 membar("#StoreLoad | #StoreStore");
99 lock
->owner_pc
= ((unsigned int)caller
);
100 lock
->owner_cpu
= cpu
;
101 current
->thread
.smp_lock_count
++;
102 current
->thread
.smp_lock_pc
= ((unsigned int)caller
);
110 void _do_spin_unlock(spinlock_t
*lock
)
113 lock
->owner_cpu
= NO_PROC_ID
;
114 membar("#StoreStore | #LoadStore");
116 current
->thread
.smp_lock_count
--;
119 /* Keep INIT_STUCK the same... */
121 void _do_read_lock (rwlock_t
*rw
, char *str
)
123 unsigned long caller
, val
;
124 int stuck
= INIT_STUCK
;
130 /* Wait for any writer to go away. */
131 while (((long)(rw
->lock
)) < 0) {
134 show_read(str
, rw
, caller
);
139 /* Try once to increment the counter. */
140 __asm__
__volatile__(
142 " brlz,a,pn %%g5, 2f\n"
144 " add %%g5, 1, %%g7\n"
145 " casx [%0], %%g5, %%g7\n"
146 " sub %%g5, %%g7, %0\n"
149 : "g5", "g7", "memory");
150 membar("#StoreLoad | #StoreStore");
153 rw
->reader_pc
[cpu
] = ((unsigned int)caller
);
154 current
->thread
.smp_lock_count
++;
155 current
->thread
.smp_lock_pc
= ((unsigned int)caller
);
160 void _do_read_unlock (rwlock_t
*rw
, char *str
)
162 unsigned long caller
, val
;
163 int stuck
= INIT_STUCK
;
169 /* Drop our identity _first_. */
170 rw
->reader_pc
[cpu
] = 0;
171 current
->thread
.smp_lock_count
--;
173 /* Spin trying to decrement the counter using casx. */
174 __asm__
__volatile__(
176 " sub %%g5, 1, %%g7\n"
177 " casx [%0], %%g5, %%g7\n"
178 " membar #StoreLoad | #StoreStore\n"
179 " sub %%g5, %%g7, %0\n"
182 : "g5", "g7", "memory");
186 show_read(str
, rw
, caller
);
195 void _do_write_lock (rwlock_t
*rw
, char *str
)
197 unsigned long caller
, val
;
198 int stuck
= INIT_STUCK
;
204 /* Spin while there is another writer. */
205 while (((long)rw
->lock
) < 0) {
208 show_write(str
, rw
, caller
);
214 /* Try to acuire the write bit. */
215 __asm__
__volatile__(
217 " sllx %%g3, 63, %%g3\n"
219 " brlz,pn %%g5, 1f\n"
220 " or %%g5, %%g3, %%g7\n"
221 " casx [%0], %%g5, %%g7\n"
222 " membar #StoreLoad | #StoreStore\n"
224 " sub %%g5, %%g7, %0\n"
228 : "g3", "g5", "g7", "memory");
230 /* We couldn't get the write bit. */
233 show_write(str
, rw
, caller
);
238 if ((rw
->lock
& ((1UL<<63)-1UL)) != 0UL) {
239 /* Readers still around, drop the write
240 * lock, spin, and try again.
244 show_write(str
, rw
, caller
);
247 __asm__
__volatile__(
249 " sllx %%g3, 63, %%g3\n"
250 "1: ldx [%0], %%g5\n"
251 " andn %%g5, %%g3, %%g7\n"
252 " casx [%0], %%g5, %%g7\n"
254 " bne,pn %%xcc, 1b\n"
255 " membar #StoreLoad | #StoreStore"
258 : "g3", "g5", "g7", "cc", "memory");
259 while(rw
->lock
!= 0) {
262 show_write(str
, rw
, caller
);
270 /* We have it, say who we are. */
271 rw
->writer_pc
= ((unsigned int)caller
);
272 rw
->writer_cpu
= cpu
;
273 current
->thread
.smp_lock_count
++;
274 current
->thread
.smp_lock_pc
= ((unsigned int)caller
);
279 void _do_write_unlock(rwlock_t
*rw
)
281 unsigned long caller
, val
;
282 int stuck
= INIT_STUCK
;
287 /* Drop our identity _first_ */
289 rw
->writer_cpu
= NO_PROC_ID
;
290 current
->thread
.smp_lock_count
--;
292 __asm__
__volatile__(
294 " sllx %%g3, 63, %%g3\n"
296 " andn %%g5, %%g3, %%g7\n"
297 " casx [%0], %%g5, %%g7\n"
298 " membar #StoreLoad | #StoreStore\n"
299 " sub %%g5, %%g7, %0\n"
302 : "g3", "g5", "g7", "memory");
306 show_write("write_unlock", rw
, caller
);
313 int _do_write_trylock (rwlock_t
*rw
, char *str
)
315 unsigned long caller
, val
;
320 /* Try to acuire the write bit. */
321 __asm__
__volatile__(
323 " sllx %%g3, 63, %%g3\n"
325 " brlz,pn %%g5, 1f\n"
326 " or %%g5, %%g3, %%g7\n"
327 " casx [%0], %%g5, %%g7\n"
328 " membar #StoreLoad | #StoreStore\n"
330 " sub %%g5, %%g7, %0\n"
334 : "g3", "g5", "g7", "memory");
341 if ((rw
->lock
& ((1UL<<63)-1UL)) != 0UL) {
342 /* Readers still around, drop the write
343 * lock, return failure.
345 __asm__
__volatile__(
347 " sllx %%g3, 63, %%g3\n"
348 "1: ldx [%0], %%g5\n"
349 " andn %%g5, %%g3, %%g7\n"
350 " casx [%0], %%g5, %%g7\n"
352 " bne,pn %%xcc, 1b\n"
353 " membar #StoreLoad | #StoreStore"
356 : "g3", "g5", "g7", "cc", "memory");
363 /* We have it, say who we are. */
364 rw
->writer_pc
= ((unsigned int)caller
);
365 rw
->writer_cpu
= cpu
;
366 current
->thread
.smp_lock_count
++;
367 current
->thread
.smp_lock_pc
= ((unsigned int)caller
);
374 #endif /* CONFIG_SMP */