arch/sparc64/lib/debuglocks.c

   1 /* $Id: debuglocks.c,v 1.9 2001/11/17 00:10:48 davem Exp $
   2  * debuglocks.c: Debugging versions of SMP locking primitives.
   3  *
   4  * Copyright (C) 1998 David S. Miller (davem@redhat.com)
   5  */
   6
   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>
  12
  13 #ifdef CONFIG_SMP
  14
  15 #define GET_CALLER(PC) __asm__ __volatile__("mov %%i7, %0" : "=r" (PC))
  16
  17 static inline void show (char *str, spinlock_t *lock, unsigned long caller)
  18 {
  19         int cpu = smp_processor_id();
  20
  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);
  24 }
  25
  26 static inline void show_read (char *str, rwlock_t *lock, unsigned long caller)
  27 {
  28         int cpu = smp_processor_id();
  29
  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);
  33 }
  34
  35 static inline void show_write (char *str, rwlock_t *lock, unsigned long caller)
  36 {
  37         int cpu = smp_processor_id();
  38         int i;
  39
  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);
  44         printk("Readers:");
  45         for (i = 0; i < NR_CPUS; i++)
  46                 if (lock->reader_pc[i])
  47                         printk(" %d[%08x]", i, lock->reader_pc[i]);
  48         printk("\n");
  49 }
  50
  51 #undef INIT_STUCK
  52 #define INIT_STUCK 100000000
  53
  54 void _do_spin_lock(spinlock_t *lock, char *str)
  55 {
  56         unsigned long caller, val;
  57         int stuck = INIT_STUCK;
  58         int cpu = get_cpu();
  59         int shown = 0;
  60
  61         GET_CALLER(caller);
  62 again:
  63         __asm__ __volatile__("ldstub [%1], %0"
  64                              : "=r" (val)
  65                              : "r" (&(lock->lock))
  66                              : "memory");
  67         membar("#StoreLoad | #StoreStore");
  68         if (val) {
  69                 while (lock->lock) {
  70                         if (!--stuck) {
  71                                 if (shown++ <= 2)
  72                                         show(str, lock, caller);
  73                                 stuck = INIT_STUCK;
  74                         }
  75                         membar("#LoadLoad");
  76                 }
  77                 goto again;
  78         }
  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);
  83
  84         put_cpu();
  85 }
  86
  87 int _spin_trylock(spinlock_t *lock)
  88 {
  89         unsigned long val, caller;
  90         int cpu = get_cpu();
  91
  92         GET_CALLER(caller);
  93         __asm__ __volatile__("ldstub [%1], %0"
  94                              : "=r" (val)
  95                              : "r" (&(lock->lock))
  96                              : "memory");
  97         membar("#StoreLoad | #StoreStore");
  98         if (!val) {
  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);
 103         }
 104
 105         put_cpu();
 106
 107         return val == 0;
 108 }
 109
 110 void _do_spin_unlock(spinlock_t *lock)
 111 {
 112         lock->owner_pc = 0;
 113         lock->owner_cpu = NO_PROC_ID;
 114         membar("#StoreStore | #LoadStore");
 115         lock->lock = 0;
 116         current->thread.smp_lock_count--;
 117 }
 118
 119 /* Keep INIT_STUCK the same... */
 120
 121 void _do_read_lock (rwlock_t *rw, char *str)
 122 {
 123         unsigned long caller, val;
 124         int stuck = INIT_STUCK;
 125         int cpu = get_cpu();
 126         int shown = 0;
 127
 128         GET_CALLER(caller);
 129 wlock_again:
 130         /* Wait for any writer to go away.  */
 131         while (((long)(rw->lock)) < 0) {
 132                 if (!--stuck) {
 133                         if (shown++ <= 2)
 134                                 show_read(str, rw, caller);
 135                         stuck = INIT_STUCK;
 136                 }
 137                 membar("#LoadLoad");
 138         }
 139         /* Try once to increment the counter.  */
 140         __asm__ __volatile__(
 141 "       ldx             [%0], %%g5\n"
 142 "       brlz,a,pn       %%g5, 2f\n"
 143 "        mov            1, %0\n"
 144 "       add             %%g5, 1, %%g7\n"
 145 "       casx            [%0], %%g5, %%g7\n"
 146 "       sub             %%g5, %%g7, %0\n"
 147 "2:"    : "=r" (val)
 148         : "0" (&(rw->lock))
 149         : "g5", "g7", "memory");
 150         membar("#StoreLoad | #StoreStore");
 151         if (val)
 152                 goto wlock_again;
 153         rw->reader_pc[cpu] = ((unsigned int)caller);
 154         current->thread.smp_lock_count++;
 155         current->thread.smp_lock_pc = ((unsigned int)caller);
 156
 157         put_cpu();
 158 }
 159
 160 void _do_read_unlock (rwlock_t *rw, char *str)
 161 {
 162         unsigned long caller, val;
 163         int stuck = INIT_STUCK;
 164         int cpu = get_cpu();
 165         int shown = 0;
 166
 167         GET_CALLER(caller);
 168
 169         /* Drop our identity _first_. */
 170         rw->reader_pc[cpu] = 0;
 171         current->thread.smp_lock_count--;
 172 runlock_again:
 173         /* Spin trying to decrement the counter using casx.  */
 174         __asm__ __volatile__(
 175 "       ldx     [%0], %%g5\n"
 176 "       sub     %%g5, 1, %%g7\n"
 177 "       casx    [%0], %%g5, %%g7\n"
 178 "       membar  #StoreLoad | #StoreStore\n"
 179 "       sub     %%g5, %%g7, %0\n"
 180         : "=r" (val)
 181         : "0" (&(rw->lock))
 182         : "g5", "g7", "memory");
 183         if (val) {
 184                 if (!--stuck) {
 185                         if (shown++ <= 2)
 186                                 show_read(str, rw, caller);
 187                         stuck = INIT_STUCK;
 188                 }
 189                 goto runlock_again;
 190         }
 191
 192         put_cpu();
 193 }
 194
 195 void _do_write_lock (rwlock_t *rw, char *str)
 196 {
 197         unsigned long caller, val;
 198         int stuck = INIT_STUCK;
 199         int cpu = get_cpu();
 200         int shown = 0;
 201
 202         GET_CALLER(caller);
 203 wlock_again:
 204         /* Spin while there is another writer. */
 205         while (((long)rw->lock) < 0) {
 206                 if (!--stuck) {
 207                         if (shown++ <= 2)
 208                                 show_write(str, rw, caller);
 209                         stuck = INIT_STUCK;
 210                 }
 211                 membar("#LoadLoad");
 212         }
 213
 214         /* Try to acuire the write bit.  */
 215         __asm__ __volatile__(
 216 "       mov     1, %%g3\n"
 217 "       sllx    %%g3, 63, %%g3\n"
 218 "       ldx     [%0], %%g5\n"
 219 "       brlz,pn %%g5, 1f\n"
 220 "        or     %%g5, %%g3, %%g7\n"
 221 "       casx    [%0], %%g5, %%g7\n"
 222 "       membar  #StoreLoad | #StoreStore\n"
 223 "       ba,pt   %%xcc, 2f\n"
 224 "        sub    %%g5, %%g7, %0\n"
 225 "1:     mov     1, %0\n"
 226 "2:"    : "=r" (val)
 227         : "0" (&(rw->lock))
 228         : "g3", "g5", "g7", "memory");
 229         if (val) {
 230                 /* We couldn't get the write bit. */
 231                 if (!--stuck) {
 232                         if (shown++ <= 2)
 233                                 show_write(str, rw, caller);
 234                         stuck = INIT_STUCK;
 235                 }
 236                 goto wlock_again;
 237         }
 238         if ((rw->lock & ((1UL<<63)-1UL)) != 0UL) {
 239                 /* Readers still around, drop the write
 240                  * lock, spin, and try again.
 241                  */
 242                 if (!--stuck) {
 243                         if (shown++ <= 2)
 244                                 show_write(str, rw, caller);
 245                         stuck = INIT_STUCK;
 246                 }
 247                 __asm__ __volatile__(
 248 "               mov     1, %%g3\n"
 249 "               sllx    %%g3, 63, %%g3\n"
 250 "1:             ldx     [%0], %%g5\n"
 251 "               andn    %%g5, %%g3, %%g7\n"
 252 "               casx    [%0], %%g5, %%g7\n"
 253 "               cmp     %%g5, %%g7\n"
 254 "               bne,pn  %%xcc, 1b\n"
 255 "                membar #StoreLoad | #StoreStore"
 256                 : /* no outputs */
 257                 : "r" (&(rw->lock))
 258                 : "g3", "g5", "g7", "cc", "memory");
 259                 while(rw->lock != 0) {
 260                         if (!--stuck) {
 261                                 if (shown++ <= 2)
 262                                         show_write(str, rw, caller);
 263                                 stuck = INIT_STUCK;
 264                         }
 265                         membar("#LoadLoad");
 266                 }
 267                 goto wlock_again;
 268         }
 269
 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);
 275
 276         put_cpu();
 277 }
 278
 279 void _do_write_unlock(rwlock_t *rw)
 280 {
 281         unsigned long caller, val;
 282         int stuck = INIT_STUCK;
 283         int shown = 0;
 284
 285         GET_CALLER(caller);
 286
 287         /* Drop our identity _first_ */
 288         rw->writer_pc = 0;
 289         rw->writer_cpu = NO_PROC_ID;
 290         current->thread.smp_lock_count--;
 291 wlock_again:
 292         __asm__ __volatile__(
 293 "       mov     1, %%g3\n"
 294 "       sllx    %%g3, 63, %%g3\n"
 295 "       ldx     [%0], %%g5\n"
 296 "       andn    %%g5, %%g3, %%g7\n"
 297 "       casx    [%0], %%g5, %%g7\n"
 298 "       membar  #StoreLoad | #StoreStore\n"
 299 "       sub     %%g5, %%g7, %0\n"
 300         : "=r" (val)
 301         : "0" (&(rw->lock))
 302         : "g3", "g5", "g7", "memory");
 303         if (val) {
 304                 if (!--stuck) {
 305                         if (shown++ <= 2)
 306                                 show_write("write_unlock", rw, caller);
 307                         stuck = INIT_STUCK;
 308                 }
 309                 goto wlock_again;
 310         }
 311 }
 312
 313 int _do_write_trylock (rwlock_t *rw, char *str)
 314 {
 315         unsigned long caller, val;
 316         int cpu = get_cpu();
 317
 318         GET_CALLER(caller);
 319
 320         /* Try to acuire the write bit.  */
 321         __asm__ __volatile__(
 322 "       mov     1, %%g3\n"
 323 "       sllx    %%g3, 63, %%g3\n"
 324 "       ldx     [%0], %%g5\n"
 325 "       brlz,pn %%g5, 1f\n"
 326 "        or     %%g5, %%g3, %%g7\n"
 327 "       casx    [%0], %%g5, %%g7\n"
 328 "       membar  #StoreLoad | #StoreStore\n"
 329 "       ba,pt   %%xcc, 2f\n"
 330 "        sub    %%g5, %%g7, %0\n"
 331 "1:     mov     1, %0\n"
 332 "2:"    : "=r" (val)
 333         : "0" (&(rw->lock))
 334         : "g3", "g5", "g7", "memory");
 335
 336         if (val) {
 337                 put_cpu();
 338                 return 0;
 339         }
 340
 341         if ((rw->lock & ((1UL<<63)-1UL)) != 0UL) {
 342                 /* Readers still around, drop the write
 343                  * lock, return failure.
 344                  */
 345                 __asm__ __volatile__(
 346 "               mov     1, %%g3\n"
 347 "               sllx    %%g3, 63, %%g3\n"
 348 "1:             ldx     [%0], %%g5\n"
 349 "               andn    %%g5, %%g3, %%g7\n"
 350 "               casx    [%0], %%g5, %%g7\n"
 351 "               cmp     %%g5, %%g7\n"
 352 "               bne,pn  %%xcc, 1b\n"
 353 "                membar #StoreLoad | #StoreStore"
 354                 : /* no outputs */
 355                 : "r" (&(rw->lock))
 356                 : "g3", "g5", "g7", "cc", "memory");
 357
 358                 put_cpu();
 359
 360                 return 0;
 361         }
 362
 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);
 368
 369         put_cpu();
 370
 371         return 1;
 372 }
 373
 374 #endif /* CONFIG_SMP */