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 #if defined(CONFIG_SMP) && defined(CONFIG_DEBUG_SPINLOCK)
  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
  39         printk("%s(%p) CPU#%d stuck at %08x\n",
  40                str, lock, cpu, (unsigned int) caller);
  41         printk("Writer: PC(%08x):CPU(%x)\n",
  42                lock->writer_pc, lock->writer_cpu);
  43         printk("Readers: 0[%08x] 1[%08x] 2[%08x] 4[%08x]\n",
  44                lock->reader_pc[0], lock->reader_pc[1],
  45                lock->reader_pc[2], lock->reader_pc[3]);
  46 }
  47
  48 #undef INIT_STUCK
  49 #define INIT_STUCK 100000000
  50
  51 void _do_spin_lock(spinlock_t *lock, char *str)
  52 {
  53         unsigned long caller, val;
  54         int stuck = INIT_STUCK;
  55         int cpu = smp_processor_id();
  56         int shown = 0;
  57
  58         GET_CALLER(caller);
  59 again:
  60         __asm__ __volatile__("ldstub [%1], %0"
  61                              : "=r" (val)
  62                              : "r" (&(lock->lock))
  63                              : "memory");
  64         membar("#StoreLoad | #StoreStore");
  65         if (val) {
  66                 while (lock->lock) {
  67                         if (!--stuck) {
  68                                 if (shown++ <= 2)
  69                                         show(str, lock, caller);
  70                                 stuck = INIT_STUCK;
  71                         }
  72                         membar("#LoadLoad");
  73                 }
  74                 goto again;
  75         }
  76         lock->owner_pc = ((unsigned int)caller);
  77         lock->owner_cpu = cpu;
  78         current->thread.smp_lock_count++;
  79         current->thread.smp_lock_pc = ((unsigned int)caller);
  80 }
  81
  82 int _spin_trylock(spinlock_t *lock)
  83 {
  84         unsigned long val, caller;
  85         int cpu = smp_processor_id();
  86
  87         GET_CALLER(caller);
  88         __asm__ __volatile__("ldstub [%1], %0"
  89                              : "=r" (val)
  90                              : "r" (&(lock->lock))
  91                              : "memory");
  92         membar("#StoreLoad | #StoreStore");
  93         if (!val) {
  94                 lock->owner_pc = ((unsigned int)caller);
  95                 lock->owner_cpu = cpu;
  96                 current->thread.smp_lock_count++;
  97                 current->thread.smp_lock_pc = ((unsigned int)caller);
  98         }
  99         return val == 0;
 100 }
 101
 102 void _do_spin_unlock(spinlock_t *lock)
 103 {
 104         lock->owner_pc = 0;
 105         lock->owner_cpu = NO_PROC_ID;
 106         membar("#StoreStore | #LoadStore");
 107         lock->lock = 0;
 108         current->thread.smp_lock_count--;
 109 }
 110
 111 /* Keep INIT_STUCK the same... */
 112
 113 void _do_read_lock (rwlock_t *rw, char *str)
 114 {
 115         unsigned long caller, val;
 116         int stuck = INIT_STUCK;
 117         int cpu = smp_processor_id();
 118         int shown = 0;
 119
 120         GET_CALLER(caller);
 121 wlock_again:
 122         /* Wait for any writer to go away.  */
 123         while (((long)(rw->lock)) < 0) {
 124                 if (!--stuck) {
 125                         if (shown++ <= 2)
 126                                 show_read(str, rw, caller);
 127                         stuck = INIT_STUCK;
 128                 }
 129                 membar("#LoadLoad");
 130         }
 131         /* Try once to increment the counter.  */
 132         __asm__ __volatile__(
 133 "       ldx             [%0], %%g5\n"
 134 "       brlz,a,pn       %%g5, 2f\n"
 135 "        mov            1, %0\n"
 136 "       add             %%g5, 1, %%g7\n"
 137 "       casx            [%0], %%g5, %%g7\n"
 138 "       sub             %%g5, %%g7, %0\n"
 139 "2:"    : "=r" (val)
 140         : "0" (&(rw->lock))
 141         : "g5", "g7", "memory");
 142         membar("#StoreLoad | #StoreStore");
 143         if (val)
 144                 goto wlock_again;
 145         rw->reader_pc[cpu] = ((unsigned int)caller);
 146         current->thread.smp_lock_count++;
 147         current->thread.smp_lock_pc = ((unsigned int)caller);
 148 }
 149
 150 void _do_read_unlock (rwlock_t *rw, char *str)
 151 {
 152         unsigned long caller, val;
 153         int stuck = INIT_STUCK;
 154         int cpu = smp_processor_id();
 155         int shown = 0;
 156
 157         GET_CALLER(caller);
 158
 159         /* Drop our identity _first_. */
 160         rw->reader_pc[cpu] = 0;
 161         current->thread.smp_lock_count--;
 162 runlock_again:
 163         /* Spin trying to decrement the counter using casx.  */
 164         __asm__ __volatile__(
 165 "       ldx     [%0], %%g5\n"
 166 "       sub     %%g5, 1, %%g7\n"
 167 "       casx    [%0], %%g5, %%g7\n"
 168 "       membar  #StoreLoad | #StoreStore\n"
 169 "       sub     %%g5, %%g7, %0\n"
 170         : "=r" (val)
 171         : "0" (&(rw->lock))
 172         : "g5", "g7", "memory");
 173         if (val) {
 174                 if (!--stuck) {
 175                         if (shown++ <= 2)
 176                                 show_read(str, rw, caller);
 177                         stuck = INIT_STUCK;
 178                 }
 179                 goto runlock_again;
 180         }
 181 }
 182
 183 void _do_write_lock (rwlock_t *rw, char *str)
 184 {
 185         unsigned long caller, val;
 186         int stuck = INIT_STUCK;
 187         int cpu = smp_processor_id();
 188         int shown = 0;
 189
 190         GET_CALLER(caller);
 191 wlock_again:
 192         /* Spin while there is another writer. */
 193         while (((long)rw->lock) < 0) {
 194                 if (!--stuck) {
 195                         if (shown++ <= 2)
 196                                 show_write(str, rw, caller);
 197                         stuck = INIT_STUCK;
 198                 }
 199                 membar("#LoadLoad");
 200         }
 201
 202         /* Try to acuire the write bit.  */
 203         __asm__ __volatile__(
 204 "       mov     1, %%g3\n"
 205 "       sllx    %%g3, 63, %%g3\n"
 206 "       ldx     [%0], %%g5\n"
 207 "       brlz,pn %%g5, 1f\n"
 208 "        or     %%g5, %%g3, %%g7\n"
 209 "       casx    [%0], %%g5, %%g7\n"
 210 "       membar  #StoreLoad | #StoreStore\n"
 211 "       ba,pt   %%xcc, 2f\n"
 212 "        sub    %%g5, %%g7, %0\n"
 213 "1:     mov     1, %0\n"
 214 "2:"    : "=r" (val)
 215         : "0" (&(rw->lock))
 216         : "g3", "g5", "g7", "memory");
 217         if (val) {
 218                 /* We couldn't get the write bit. */
 219                 if (!--stuck) {
 220                         if (shown++ <= 2)
 221                                 show_write(str, rw, caller);
 222                         stuck = INIT_STUCK;
 223                 }
 224                 goto wlock_again;
 225         }
 226         if ((rw->lock & ((1UL<<63)-1UL)) != 0UL) {
 227                 /* Readers still around, drop the write
 228                  * lock, spin, and try again.
 229                  */
 230                 if (!--stuck) {
 231                         if (shown++ <= 2)
 232                                 show_write(str, rw, caller);
 233                         stuck = INIT_STUCK;
 234                 }
 235                 __asm__ __volatile__(
 236 "               mov     1, %%g3\n"
 237 "               sllx    %%g3, 63, %%g3\n"
 238 "1:             ldx     [%0], %%g5\n"
 239 "               andn    %%g5, %%g3, %%g7\n"
 240 "               casx    [%0], %%g5, %%g7\n"
 241 "               cmp     %%g5, %%g7\n"
 242 "               bne,pn  %%xcc, 1b\n"
 243 "                membar #StoreLoad | #StoreStore"
 244                 : /* no outputs */
 245                 : "r" (&(rw->lock))
 246                 : "g3", "g5", "g7", "cc", "memory");
 247                 while(rw->lock != 0) {
 248                         if (!--stuck) {
 249                                 if (shown++ <= 2)
 250                                         show_write(str, rw, caller);
 251                                 stuck = INIT_STUCK;
 252                         }
 253                         membar("#LoadLoad");
 254                 }
 255                 goto wlock_again;
 256         }
 257
 258         /* We have it, say who we are. */
 259         rw->writer_pc = ((unsigned int)caller);
 260         rw->writer_cpu = cpu;
 261         current->thread.smp_lock_count++;
 262         current->thread.smp_lock_pc = ((unsigned int)caller);
 263 }
 264
 265 void _do_write_unlock(rwlock_t *rw)
 266 {
 267         unsigned long caller, val;
 268         int stuck = INIT_STUCK;
 269         int shown = 0;
 270
 271         GET_CALLER(caller);
 272
 273         /* Drop our identity _first_ */
 274         rw->writer_pc = 0;
 275         rw->writer_cpu = NO_PROC_ID;
 276         current->thread.smp_lock_count--;
 277 wlock_again:
 278         __asm__ __volatile__(
 279 "       mov     1, %%g3\n"
 280 "       sllx    %%g3, 63, %%g3\n"
 281 "       ldx     [%0], %%g5\n"
 282 "       andn    %%g5, %%g3, %%g7\n"
 283 "       casx    [%0], %%g5, %%g7\n"
 284 "       membar  #StoreLoad | #StoreStore\n"
 285 "       sub     %%g5, %%g7, %0\n"
 286         : "=r" (val)
 287         : "0" (&(rw->lock))
 288         : "g3", "g5", "g7", "memory");
 289         if (val) {
 290                 if (!--stuck) {
 291                         if (shown++ <= 2)
 292                                 show_write("write_unlock", rw, caller);
 293                         stuck = INIT_STUCK;
 294                 }
 295                 goto wlock_again;
 296         }
 297 }
 298
 299 #endif /* CONFIG_SMP && CONFIG_DEBUG_SPINLOCK */