arch/sparc/lib/debuglocks.c

   1 /* $Id: debuglocks.c,v 1.11 2001/09/20 00:35:31 davem Exp $
   2  * debuglocks.c: Debugging versions of SMP locking primitives.
   3  *
   4  * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
   5  * Copyright (C) 1998-99 Anton Blanchard (anton@progsoc.uts.edu.au)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/sched.h>
  10 #include <linux/threads.h>      /* For NR_CPUS */
  11 #include <linux/spinlock.h>
  12 #include <asm/psr.h>
  13 #include <asm/system.h>
  14
  15 #ifdef CONFIG_SMP
  16
  17 /* Some notes on how these debugging routines work.  When a lock is acquired
  18  * an extra debugging member lock->owner_pc is set to the caller of the lock
  19  * acquisition routine.  Right before releasing a lock, the debugging program
  20  * counter is cleared to zero.
  21  *
  22  * Furthermore, since PC's are 4 byte aligned on Sparc, we stuff the CPU
  23  * number of the owner in the lowest two bits.
  24  */
  25
  26 #define STORE_CALLER(A) __asm__ __volatile__("mov %%i7, %0" : "=r" (A));
  27
  28 static inline void show(char *str, spinlock_t *lock, unsigned long caller)
  29 {
  30         int cpu = smp_processor_id();
  31
  32         printk("%s(%p) CPU#%d stuck at %08lx, owner PC(%08lx):CPU(%lx)\n",str,
  33                 lock, cpu, caller, lock->owner_pc & ~3, lock->owner_pc & 3);
  34 }
  35
  36 static inline void show_read(char *str, rwlock_t *lock, unsigned long caller)
  37 {
  38         int cpu = smp_processor_id();
  39
  40         printk("%s(%p) CPU#%d stuck at %08lx, owner PC(%08lx):CPU(%lx)\n", str,
  41                 lock, cpu, caller, lock->owner_pc & ~3, lock->owner_pc & 3);
  42 }
  43
  44 static inline void show_write(char *str, rwlock_t *lock, unsigned long caller)
  45 {
  46         int cpu = smp_processor_id();
  47         int i;
  48
  49         printk("%s(%p) CPU#%d stuck at %08lx, owner PC(%08lx):CPU(%lx)", str,
  50                 lock, cpu, caller, lock->owner_pc & ~3, lock->owner_pc & 3);
  51
  52         for(i = 0; i < NR_CPUS; i++)
  53                 printk(" reader[%d]=%08lx", i, lock->reader_pc[i]);
  54
  55         printk("\n");
  56 }
  57
  58 #undef INIT_STUCK
  59 #define INIT_STUCK 100000000
  60
  61 void _do_spin_lock(spinlock_t *lock, char *str)
  62 {
  63         unsigned long caller;
  64         unsigned long val;
  65         int cpu = smp_processor_id();
  66         int stuck = INIT_STUCK;
  67
  68         STORE_CALLER(caller);
  69
  70 again:
  71         __asm__ __volatile__("ldstub [%1], %0" : "=r" (val) : "r" (&(lock->lock)));
  72         if(val) {
  73                 while(lock->lock) {
  74                         if (!--stuck) {
  75                                 show(str, lock, caller);
  76                                 stuck = INIT_STUCK;
  77                         }
  78                         barrier();
  79                 }
  80                 goto again;
  81         }
  82         lock->owner_pc = (cpu & 3) | (caller & ~3);
  83 }
  84
  85 int _spin_trylock(spinlock_t *lock)
  86 {
  87         unsigned long val;
  88         unsigned long caller;
  89         int cpu = smp_processor_id();
  90
  91         STORE_CALLER(caller);
  92
  93         __asm__ __volatile__("ldstub [%1], %0" : "=r" (val) : "r" (&(lock->lock)));
  94         if(!val) {
  95                 /* We got it, record our identity for debugging. */
  96                 lock->owner_pc = (cpu & 3) | (caller & ~3);
  97         }
  98         return val == 0;
  99 }
 100
 101 void _do_spin_unlock(spinlock_t *lock)
 102 {
 103         lock->owner_pc = 0;
 104         barrier();
 105         lock->lock = 0;
 106 }
 107
 108 void _do_read_lock(rwlock_t *rw, char *str)
 109 {
 110         unsigned long caller;
 111         unsigned long val;
 112         int cpu = smp_processor_id();
 113         int stuck = INIT_STUCK;
 114
 115         STORE_CALLER(caller);
 116
 117 wlock_again:
 118         __asm__ __volatile__("ldstub [%1 + 3], %0" : "=r" (val) : "r" (&(rw->lock)));
 119         if(val) {
 120                 while(rw->lock & 0xff) {
 121                         if (!--stuck) {
 122                                 show_read(str, rw, caller);
 123                                 stuck = INIT_STUCK;
 124                         }
 125                         barrier();
 126                 }
 127                 goto wlock_again;
 128         }
 129
 130         rw->reader_pc[cpu] = caller;
 131         barrier();
 132         rw->lock++;
 133 }
 134
 135 void _do_read_unlock(rwlock_t *rw, char *str)
 136 {
 137         unsigned long caller;
 138         unsigned long val;
 139         int cpu = smp_processor_id();
 140         int stuck = INIT_STUCK;
 141
 142         STORE_CALLER(caller);
 143
 144 wlock_again:
 145         __asm__ __volatile__("ldstub [%1 + 3], %0" : "=r" (val) : "r" (&(rw->lock)));
 146         if(val) {
 147                 while(rw->lock & 0xff) {
 148                         if (!--stuck) {
 149                                 show_read(str, rw, caller);
 150                                 stuck = INIT_STUCK;
 151                         }
 152                         barrier();
 153                 }
 154                 goto wlock_again;
 155         }
 156
 157         rw->reader_pc[cpu] = 0;
 158         barrier();
 159         rw->lock -= 0x1ff;
 160 }
 161
 162 void _do_write_lock(rwlock_t *rw, char *str)
 163 {
 164         unsigned long caller;
 165         unsigned long val;
 166         int cpu = smp_processor_id();
 167         int stuck = INIT_STUCK;
 168
 169         STORE_CALLER(caller);
 170
 171 wlock_again:
 172         __asm__ __volatile__("ldstub [%1 + 3], %0" : "=r" (val) : "r" (&(rw->lock)));
 173         if(val) {
 174 wlock_wait:
 175                 while(rw->lock) {
 176                         if (!--stuck) {
 177                                 show_write(str, rw, caller);
 178                                 stuck = INIT_STUCK;
 179                         }
 180                         barrier();
 181                 }
 182                 goto wlock_again;
 183         }
 184
 185         if (rw->lock & ~0xff) {
 186                 *(((unsigned char *)&rw->lock)+3) = 0;
 187                 barrier();
 188                 goto wlock_wait;
 189         }
 190
 191         barrier();
 192         rw->owner_pc = (cpu & 3) | (caller & ~3);
 193 }
 194
 195 void _do_write_unlock(rwlock_t *rw)
 196 {
 197         rw->owner_pc = 0;
 198         barrier();
 199         rw->lock = 0;
 200 }
 201
 202 #endif /* SMP */