arch/powerpc/platforms/cell/spufs/run.c

   1 #define DEBUG
   2
   3 #include <linux/wait.h>
   4 #include <linux/ptrace.h>
   5
   6 #include <asm/spu.h>
   7 #include <asm/spu_priv1.h>
   8 #include <asm/io.h>
   9 #include <asm/unistd.h>
  10
  11 #include "spufs.h"
  12
  13 /* interrupt-level stop callback function. */
  14 void spufs_stop_callback(struct spu *spu, int irq)
  15 {
  16         struct spu_context *ctx = spu->ctx;
  17
  18         /*
  19          * It should be impossible to preempt a context while an exception
  20          * is being processed, since the context switch code is specially
  21          * coded to deal with interrupts ... But, just in case, sanity check
  22          * the context pointer.  It is OK to return doing nothing since
  23          * the exception will be regenerated when the context is resumed.
  24          */
  25         if (ctx) {
  26                 /* Copy exception arguments into module specific structure */
  27                 switch(irq) {
  28                 case 0 :
  29                         ctx->csa.class_0_pending = spu->class_0_pending;
  30                         ctx->csa.class_0_dar = spu->class_0_dar;
  31                         break;
  32                 case 1 :
  33                         ctx->csa.class_1_dsisr = spu->class_1_dsisr;
  34                         ctx->csa.class_1_dar = spu->class_1_dar;
  35                         break;
  36                 case 2 :
  37                         break;
  38                 }
  39
  40                 /* ensure that the exception status has hit memory before a
  41                  * thread waiting on the context's stop queue is woken */
  42                 smp_wmb();
  43
  44                 wake_up_all(&ctx->stop_wq);
  45         }
  46 }
  47
  48 int spu_stopped(struct spu_context *ctx, u32 *stat)
  49 {
  50         u64 dsisr;
  51         u32 stopped;
  52
  53         stopped = SPU_STATUS_INVALID_INSTR | SPU_STATUS_SINGLE_STEP |
  54                 SPU_STATUS_STOPPED_BY_HALT | SPU_STATUS_STOPPED_BY_STOP;
  55
  56 top:
  57         *stat = ctx->ops->status_read(ctx);
  58         if (*stat & stopped) {
  59                 /*
  60                  * If the spu hasn't finished stopping, we need to
  61                  * re-read the register to get the stopped value.
  62                  */
  63                 if (*stat & SPU_STATUS_RUNNING)
  64                         goto top;
  65                 return 1;
  66         }
  67
  68         if (test_bit(SPU_SCHED_NOTIFY_ACTIVE, &ctx->sched_flags))
  69                 return 1;
  70
  71         dsisr = ctx->csa.class_1_dsisr;
  72         if (dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED))
  73                 return 1;
  74
  75         if (ctx->csa.class_0_pending)
  76                 return 1;
  77
  78         return 0;
  79 }
  80
  81 static int spu_setup_isolated(struct spu_context *ctx)
  82 {
  83         int ret;
  84         u64 __iomem *mfc_cntl;
  85         u64 sr1;
  86         u32 status;
  87         unsigned long timeout;
  88         const u32 status_loading = SPU_STATUS_RUNNING
  89                 | SPU_STATUS_ISOLATED_STATE | SPU_STATUS_ISOLATED_LOAD_STATUS;
  90
  91         ret = -ENODEV;
  92         if (!isolated_loader)
  93                 goto out;
  94
  95         /*
  96          * We need to exclude userspace access to the context.
  97          *
  98          * To protect against memory access we invalidate all ptes
  99          * and make sure the pagefault handlers block on the mutex.
 100          */
 101         spu_unmap_mappings(ctx);
 102
 103         mfc_cntl = &ctx->spu->priv2->mfc_control_RW;
 104
 105         /* purge the MFC DMA queue to ensure no spurious accesses before we
 106          * enter kernel mode */
 107         timeout = jiffies + HZ;
 108         out_be64(mfc_cntl, MFC_CNTL_PURGE_DMA_REQUEST);
 109         while ((in_be64(mfc_cntl) & MFC_CNTL_PURGE_DMA_STATUS_MASK)
 110                         != MFC_CNTL_PURGE_DMA_COMPLETE) {
 111                 if (time_after(jiffies, timeout)) {
 112                         printk(KERN_ERR "%s: timeout flushing MFC DMA queue\n",
 113                                         __func__);
 114                         ret = -EIO;
 115                         goto out;
 116                 }
 117                 cond_resched();
 118         }
 119
 120         /* clear purge status */
 121         out_be64(mfc_cntl, 0);
 122
 123         /* put the SPE in kernel mode to allow access to the loader */
 124         sr1 = spu_mfc_sr1_get(ctx->spu);
 125         sr1 &= ~MFC_STATE1_PROBLEM_STATE_MASK;
 126         spu_mfc_sr1_set(ctx->spu, sr1);
 127
 128         /* start the loader */
 129         ctx->ops->signal1_write(ctx, (unsigned long)isolated_loader >> 32);
 130         ctx->ops->signal2_write(ctx,
 131                         (unsigned long)isolated_loader & 0xffffffff);
 132
 133         ctx->ops->runcntl_write(ctx,
 134                         SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
 135
 136         ret = 0;
 137         timeout = jiffies + HZ;
 138         while (((status = ctx->ops->status_read(ctx)) & status_loading) ==
 139                                 status_loading) {
 140                 if (time_after(jiffies, timeout)) {
 141                         printk(KERN_ERR "%s: timeout waiting for loader\n",
 142                                         __func__);
 143                         ret = -EIO;
 144                         goto out_drop_priv;
 145                 }
 146                 cond_resched();
 147         }
 148
 149         if (!(status & SPU_STATUS_RUNNING)) {
 150                 /* If isolated LOAD has failed: run SPU, we will get a stop-and
 151                  * signal later. */
 152                 pr_debug("%s: isolated LOAD failed\n", __func__);
 153                 ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
 154                 ret = -EACCES;
 155                 goto out_drop_priv;
 156         }
 157
 158         if (!(status & SPU_STATUS_ISOLATED_STATE)) {
 159                 /* This isn't allowed by the CBEA, but check anyway */
 160                 pr_debug("%s: SPU fell out of isolated mode?\n", __func__);
 161                 ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_STOP);
 162                 ret = -EINVAL;
 163                 goto out_drop_priv;
 164         }
 165
 166 out_drop_priv:
 167         /* Finished accessing the loader. Drop kernel mode */
 168         sr1 |= MFC_STATE1_PROBLEM_STATE_MASK;
 169         spu_mfc_sr1_set(ctx->spu, sr1);
 170
 171 out:
 172         return ret;
 173 }
 174
 175 static int spu_run_init(struct spu_context *ctx, u32 *npc)
 176 {
 177         unsigned long runcntl = SPU_RUNCNTL_RUNNABLE;
 178         int ret;
 179
 180         spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 181
 182         /*
 183          * NOSCHED is synchronous scheduling with respect to the caller.
 184          * The caller waits for the context to be loaded.
 185          */
 186         if (ctx->flags & SPU_CREATE_NOSCHED) {
 187                 if (ctx->state == SPU_STATE_SAVED) {
 188                         ret = spu_activate(ctx, 0);
 189                         if (ret)
 190                                 return ret;
 191                 }
 192         }
 193
 194         /*
 195          * Apply special setup as required.
 196          */
 197         if (ctx->flags & SPU_CREATE_ISOLATE) {
 198                 if (!(ctx->ops->status_read(ctx) & SPU_STATUS_ISOLATED_STATE)) {
 199                         ret = spu_setup_isolated(ctx);
 200                         if (ret)
 201                                 return ret;
 202                 }
 203
 204                 /*
 205                  * If userspace has set the runcntrl register (eg, to
 206                  * issue an isolated exit), we need to re-set it here
 207                  */
 208                 runcntl = ctx->ops->runcntl_read(ctx) &
 209                         (SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
 210                 if (runcntl == 0)
 211                         runcntl = SPU_RUNCNTL_RUNNABLE;
 212         } else {
 213                 unsigned long privcntl;
 214
 215                 if (test_thread_flag(TIF_SINGLESTEP))
 216                         privcntl = SPU_PRIVCNTL_MODE_SINGLE_STEP;
 217                 else
 218                         privcntl = SPU_PRIVCNTL_MODE_NORMAL;
 219
 220                 ctx->ops->privcntl_write(ctx, privcntl);
 221                 ctx->ops->npc_write(ctx, *npc);
 222         }
 223
 224         ctx->ops->runcntl_write(ctx, runcntl);
 225
 226         if (ctx->flags & SPU_CREATE_NOSCHED) {
 227                 spuctx_switch_state(ctx, SPU_UTIL_USER);
 228         } else {
 229
 230                 if (ctx->state == SPU_STATE_SAVED) {
 231                         ret = spu_activate(ctx, 0);
 232                         if (ret)
 233                                 return ret;
 234                 } else {
 235                         spuctx_switch_state(ctx, SPU_UTIL_USER);
 236                 }
 237         }
 238
 239         set_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags);
 240         return 0;
 241 }
 242
 243 static int spu_run_fini(struct spu_context *ctx, u32 *npc,
 244                                u32 *status)
 245 {
 246         int ret = 0;
 247
 248         spu_del_from_rq(ctx);
 249
 250         *status = ctx->ops->status_read(ctx);
 251         *npc = ctx->ops->npc_read(ctx);
 252
 253         spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
 254         clear_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags);
 255         spu_switch_log_notify(NULL, ctx, SWITCH_LOG_EXIT, *status);
 256         spu_release(ctx);
 257
 258         if (signal_pending(current))
 259                 ret = -ERESTARTSYS;
 260
 261         return ret;
 262 }
 263
 264 /*
 265  * SPU syscall restarting is tricky because we violate the basic
 266  * assumption that the signal handler is running on the interrupted
 267  * thread. Here instead, the handler runs on PowerPC user space code,
 268  * while the syscall was called from the SPU.
 269  * This means we can only do a very rough approximation of POSIX
 270  * signal semantics.
 271  */
 272 static int spu_handle_restartsys(struct spu_context *ctx, long *spu_ret,
 273                           unsigned int *npc)
 274 {
 275         int ret;
 276
 277         switch (*spu_ret) {
 278         case -ERESTARTSYS:
 279         case -ERESTARTNOINTR:
 280                 /*
 281                  * Enter the regular syscall restarting for
 282                  * sys_spu_run, then restart the SPU syscall
 283                  * callback.
 284                  */
 285                 *npc -= 8;
 286                 ret = -ERESTARTSYS;
 287                 break;
 288         case -ERESTARTNOHAND:
 289         case -ERESTART_RESTARTBLOCK:
 290                 /*
 291                  * Restart block is too hard for now, just return -EINTR
 292                  * to the SPU.
 293                  * ERESTARTNOHAND comes from sys_pause, we also return
 294                  * -EINTR from there.
 295                  * Assume that we need to be restarted ourselves though.
 296                  */
 297                 *spu_ret = -EINTR;
 298                 ret = -ERESTARTSYS;
 299                 break;
 300         default:
 301                 printk(KERN_WARNING "%s: unexpected return code %ld\n",
 302                         __func__, *spu_ret);
 303                 ret = 0;
 304         }
 305         return ret;
 306 }
 307
 308 static int spu_process_callback(struct spu_context *ctx)
 309 {
 310         struct spu_syscall_block s;
 311         u32 ls_pointer, npc;
 312         void __iomem *ls;
 313         long spu_ret;
 314         int ret;
 315
 316         /* get syscall block from local store */
 317         npc = ctx->ops->npc_read(ctx) & ~3;
 318         ls = (void __iomem *)ctx->ops->get_ls(ctx);
 319         ls_pointer = in_be32(ls + npc);
 320         if (ls_pointer > (LS_SIZE - sizeof(s)))
 321                 return -EFAULT;
 322         memcpy_fromio(&s, ls + ls_pointer, sizeof(s));
 323
 324         /* do actual syscall without pinning the spu */
 325         ret = 0;
 326         spu_ret = -ENOSYS;
 327         npc += 4;
 328
 329         if (s.nr_ret < NR_syscalls) {
 330                 spu_release(ctx);
 331                 /* do actual system call from here */
 332                 spu_ret = spu_sys_callback(&s);
 333                 if (spu_ret <= -ERESTARTSYS) {
 334                         ret = spu_handle_restartsys(ctx, &spu_ret, &npc);
 335                 }
 336                 mutex_lock(&ctx->state_mutex);
 337                 if (ret == -ERESTARTSYS)
 338                         return ret;
 339         }
 340
 341         /* need to re-get the ls, as it may have changed when we released the
 342          * spu */
 343         ls = (void __iomem *)ctx->ops->get_ls(ctx);
 344
 345         /* write result, jump over indirect pointer */
 346         memcpy_toio(ls + ls_pointer, &spu_ret, sizeof(spu_ret));
 347         ctx->ops->npc_write(ctx, npc);
 348         ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
 349         return ret;
 350 }
 351
 352 long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
 353 {
 354         int ret;
 355         struct spu *spu;
 356         u32 status;
 357
 358         if (mutex_lock_interruptible(&ctx->run_mutex))
 359                 return -ERESTARTSYS;
 360
 361         ctx->event_return = 0;
 362
 363         ret = spu_acquire(ctx);
 364         if (ret)
 365                 goto out_unlock;
 366
 367         spu_enable_spu(ctx);
 368
 369         spu_update_sched_info(ctx);
 370
 371         ret = spu_run_init(ctx, npc);
 372         if (ret) {
 373                 spu_release(ctx);
 374                 goto out;
 375         }
 376
 377         do {
 378                 ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, &status));
 379                 if (unlikely(ret)) {
 380                         /*
 381                          * This is nasty: we need the state_mutex for all the
 382                          * bookkeeping even if the syscall was interrupted by
 383                          * a signal. ewww.
 384                          */
 385                         mutex_lock(&ctx->state_mutex);
 386                         break;
 387                 }
 388                 spu = ctx->spu;
 389                 if (unlikely(test_and_clear_bit(SPU_SCHED_NOTIFY_ACTIVE,
 390                                                 &ctx->sched_flags))) {
 391                         if (!(status & SPU_STATUS_STOPPED_BY_STOP)) {
 392                                 spu_switch_notify(spu, ctx);
 393                                 continue;
 394                         }
 395                 }
 396
 397                 spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 398
 399                 if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 400                     (status >> SPU_STOP_STATUS_SHIFT == 0x2104)) {
 401                         ret = spu_process_callback(ctx);
 402                         if (ret)
 403                                 break;
 404                         status &= ~SPU_STATUS_STOPPED_BY_STOP;
 405                 }
 406                 ret = spufs_handle_class1(ctx);
 407                 if (ret)
 408                         break;
 409
 410                 ret = spufs_handle_class0(ctx);
 411                 if (ret)
 412                         break;
 413
 414                 if (signal_pending(current))
 415                         ret = -ERESTARTSYS;
 416         } while (!ret && !(status & (SPU_STATUS_STOPPED_BY_STOP |
 417                                       SPU_STATUS_STOPPED_BY_HALT |
 418                                        SPU_STATUS_SINGLE_STEP)));
 419
 420         spu_disable_spu(ctx);
 421         ret = spu_run_fini(ctx, npc, &status);
 422         spu_yield(ctx);
 423
 424         if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 425             (((status >> SPU_STOP_STATUS_SHIFT) & 0x3f00) == 0x2100))
 426                 ctx->stats.libassist++;
 427
 428         if ((ret == 0) ||
 429             ((ret == -ERESTARTSYS) &&
 430              ((status & SPU_STATUS_STOPPED_BY_HALT) ||
 431               (status & SPU_STATUS_SINGLE_STEP) ||
 432               ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 433                (status >> SPU_STOP_STATUS_SHIFT != 0x2104)))))
 434                 ret = status;
 435
 436         /* Note: we don't need to force_sig SIGTRAP on single-step
 437          * since we have TIF_SINGLESTEP set, thus the kernel will do
 438          * it upon return from the syscall anyawy
 439          */
 440         if (unlikely(status & SPU_STATUS_SINGLE_STEP))
 441                 ret = -ERESTARTSYS;
 442
 443         else if (unlikely((status & SPU_STATUS_STOPPED_BY_STOP)
 444             && (status >> SPU_STOP_STATUS_SHIFT) == 0x3fff)) {
 445                 force_sig(SIGTRAP, current);
 446                 ret = -ERESTARTSYS;
 447         }
 448
 449 out:
 450         *event = ctx->event_return;
 451 out_unlock:
 452         mutex_unlock(&ctx->run_mutex);
 453         return ret;
 454 }