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         /* put the SPE in kernel mode to allow access to the loader */
 121         sr1 = spu_mfc_sr1_get(ctx->spu);
 122         sr1 &= ~MFC_STATE1_PROBLEM_STATE_MASK;
 123         spu_mfc_sr1_set(ctx->spu, sr1);
 124
 125         /* start the loader */
 126         ctx->ops->signal1_write(ctx, (unsigned long)isolated_loader >> 32);
 127         ctx->ops->signal2_write(ctx,
 128                         (unsigned long)isolated_loader & 0xffffffff);
 129
 130         ctx->ops->runcntl_write(ctx,
 131                         SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
 132
 133         ret = 0;
 134         timeout = jiffies + HZ;
 135         while (((status = ctx->ops->status_read(ctx)) & status_loading) ==
 136                                 status_loading) {
 137                 if (time_after(jiffies, timeout)) {
 138                         printk(KERN_ERR "%s: timeout waiting for loader\n",
 139                                         __func__);
 140                         ret = -EIO;
 141                         goto out_drop_priv;
 142                 }
 143                 cond_resched();
 144         }
 145
 146         if (!(status & SPU_STATUS_RUNNING)) {
 147                 /* If isolated LOAD has failed: run SPU, we will get a stop-and
 148                  * signal later. */
 149                 pr_debug("%s: isolated LOAD failed\n", __func__);
 150                 ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
 151                 ret = -EACCES;
 152                 goto out_drop_priv;
 153         }
 154
 155         if (!(status & SPU_STATUS_ISOLATED_STATE)) {
 156                 /* This isn't allowed by the CBEA, but check anyway */
 157                 pr_debug("%s: SPU fell out of isolated mode?\n", __func__);
 158                 ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_STOP);
 159                 ret = -EINVAL;
 160                 goto out_drop_priv;
 161         }
 162
 163 out_drop_priv:
 164         /* Finished accessing the loader. Drop kernel mode */
 165         sr1 |= MFC_STATE1_PROBLEM_STATE_MASK;
 166         spu_mfc_sr1_set(ctx->spu, sr1);
 167
 168 out:
 169         return ret;
 170 }
 171
 172 static int spu_run_init(struct spu_context *ctx, u32 *npc)
 173 {
 174         unsigned long runcntl = SPU_RUNCNTL_RUNNABLE;
 175         int ret;
 176
 177         spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 178
 179         /*
 180          * NOSCHED is synchronous scheduling with respect to the caller.
 181          * The caller waits for the context to be loaded.
 182          */
 183         if (ctx->flags & SPU_CREATE_NOSCHED) {
 184                 if (ctx->state == SPU_STATE_SAVED) {
 185                         ret = spu_activate(ctx, 0);
 186                         if (ret)
 187                                 return ret;
 188                 }
 189         }
 190
 191         /*
 192          * Apply special setup as required.
 193          */
 194         if (ctx->flags & SPU_CREATE_ISOLATE) {
 195                 if (!(ctx->ops->status_read(ctx) & SPU_STATUS_ISOLATED_STATE)) {
 196                         ret = spu_setup_isolated(ctx);
 197                         if (ret)
 198                                 return ret;
 199                 }
 200
 201                 /*
 202                  * If userspace has set the runcntrl register (eg, to
 203                  * issue an isolated exit), we need to re-set it here
 204                  */
 205                 runcntl = ctx->ops->runcntl_read(ctx) &
 206                         (SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
 207                 if (runcntl == 0)
 208                         runcntl = SPU_RUNCNTL_RUNNABLE;
 209         } else {
 210                 unsigned long privcntl;
 211
 212                 if (test_thread_flag(TIF_SINGLESTEP))
 213                         privcntl = SPU_PRIVCNTL_MODE_SINGLE_STEP;
 214                 else
 215                         privcntl = SPU_PRIVCNTL_MODE_NORMAL;
 216
 217                 ctx->ops->privcntl_write(ctx, privcntl);
 218                 ctx->ops->npc_write(ctx, *npc);
 219         }
 220
 221         ctx->ops->runcntl_write(ctx, runcntl);
 222
 223         if (ctx->flags & SPU_CREATE_NOSCHED) {
 224                 spuctx_switch_state(ctx, SPU_UTIL_USER);
 225         } else {
 226
 227                 if (ctx->state == SPU_STATE_SAVED) {
 228                         ret = spu_activate(ctx, 0);
 229                         if (ret)
 230                                 return ret;
 231                 } else {
 232                         spuctx_switch_state(ctx, SPU_UTIL_USER);
 233                 }
 234         }
 235
 236         set_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags);
 237         return 0;
 238 }
 239
 240 static int spu_run_fini(struct spu_context *ctx, u32 *npc,
 241                                u32 *status)
 242 {
 243         int ret = 0;
 244
 245         spu_del_from_rq(ctx);
 246
 247         *status = ctx->ops->status_read(ctx);
 248         *npc = ctx->ops->npc_read(ctx);
 249
 250         spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
 251         clear_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags);
 252         spu_release(ctx);
 253
 254         if (signal_pending(current))
 255                 ret = -ERESTARTSYS;
 256
 257         return ret;
 258 }
 259
 260 /*
 261  * SPU syscall restarting is tricky because we violate the basic
 262  * assumption that the signal handler is running on the interrupted
 263  * thread. Here instead, the handler runs on PowerPC user space code,
 264  * while the syscall was called from the SPU.
 265  * This means we can only do a very rough approximation of POSIX
 266  * signal semantics.
 267  */
 268 static int spu_handle_restartsys(struct spu_context *ctx, long *spu_ret,
 269                           unsigned int *npc)
 270 {
 271         int ret;
 272
 273         switch (*spu_ret) {
 274         case -ERESTARTSYS:
 275         case -ERESTARTNOINTR:
 276                 /*
 277                  * Enter the regular syscall restarting for
 278                  * sys_spu_run, then restart the SPU syscall
 279                  * callback.
 280                  */
 281                 *npc -= 8;
 282                 ret = -ERESTARTSYS;
 283                 break;
 284         case -ERESTARTNOHAND:
 285         case -ERESTART_RESTARTBLOCK:
 286                 /*
 287                  * Restart block is too hard for now, just return -EINTR
 288                  * to the SPU.
 289                  * ERESTARTNOHAND comes from sys_pause, we also return
 290                  * -EINTR from there.
 291                  * Assume that we need to be restarted ourselves though.
 292                  */
 293                 *spu_ret = -EINTR;
 294                 ret = -ERESTARTSYS;
 295                 break;
 296         default:
 297                 printk(KERN_WARNING "%s: unexpected return code %ld\n",
 298                         __func__, *spu_ret);
 299                 ret = 0;
 300         }
 301         return ret;
 302 }
 303
 304 static int spu_process_callback(struct spu_context *ctx)
 305 {
 306         struct spu_syscall_block s;
 307         u32 ls_pointer, npc;
 308         void __iomem *ls;
 309         long spu_ret;
 310         int ret;
 311
 312         /* get syscall block from local store */
 313         npc = ctx->ops->npc_read(ctx) & ~3;
 314         ls = (void __iomem *)ctx->ops->get_ls(ctx);
 315         ls_pointer = in_be32(ls + npc);
 316         if (ls_pointer > (LS_SIZE - sizeof(s)))
 317                 return -EFAULT;
 318         memcpy_fromio(&s, ls + ls_pointer, sizeof(s));
 319
 320         /* do actual syscall without pinning the spu */
 321         ret = 0;
 322         spu_ret = -ENOSYS;
 323         npc += 4;
 324
 325         if (s.nr_ret < __NR_syscalls) {
 326                 spu_release(ctx);
 327                 /* do actual system call from here */
 328                 spu_ret = spu_sys_callback(&s);
 329                 if (spu_ret <= -ERESTARTSYS) {
 330                         ret = spu_handle_restartsys(ctx, &spu_ret, &npc);
 331                 }
 332                 mutex_lock(&ctx->state_mutex);
 333                 if (ret == -ERESTARTSYS)
 334                         return ret;
 335         }
 336
 337         /* need to re-get the ls, as it may have changed when we released the
 338          * spu */
 339         ls = (void __iomem *)ctx->ops->get_ls(ctx);
 340
 341         /* write result, jump over indirect pointer */
 342         memcpy_toio(ls + ls_pointer, &spu_ret, sizeof(spu_ret));
 343         ctx->ops->npc_write(ctx, npc);
 344         ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
 345         return ret;
 346 }
 347
 348 long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
 349 {
 350         int ret;
 351         struct spu *spu;
 352         u32 status;
 353
 354         if (mutex_lock_interruptible(&ctx->run_mutex))
 355                 return -ERESTARTSYS;
 356
 357         ctx->event_return = 0;
 358
 359         ret = spu_acquire(ctx);
 360         if (ret)
 361                 goto out_unlock;
 362
 363         spu_enable_spu(ctx);
 364
 365         spu_update_sched_info(ctx);
 366
 367         ret = spu_run_init(ctx, npc);
 368         if (ret) {
 369                 spu_release(ctx);
 370                 goto out;
 371         }
 372
 373         do {
 374                 ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, &status));
 375                 if (unlikely(ret)) {
 376                         /*
 377                          * This is nasty: we need the state_mutex for all the
 378                          * bookkeeping even if the syscall was interrupted by
 379                          * a signal. ewww.
 380                          */
 381                         mutex_lock(&ctx->state_mutex);
 382                         break;
 383                 }
 384                 spu = ctx->spu;
 385                 if (unlikely(test_and_clear_bit(SPU_SCHED_NOTIFY_ACTIVE,
 386                                                 &ctx->sched_flags))) {
 387                         if (!(status & SPU_STATUS_STOPPED_BY_STOP)) {
 388                                 spu_switch_notify(spu, ctx);
 389                                 continue;
 390                         }
 391                 }
 392
 393                 spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 394
 395                 if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 396                     (status >> SPU_STOP_STATUS_SHIFT == 0x2104)) {
 397                         ret = spu_process_callback(ctx);
 398                         if (ret)
 399                                 break;
 400                         status &= ~SPU_STATUS_STOPPED_BY_STOP;
 401                 }
 402                 ret = spufs_handle_class1(ctx);
 403                 if (ret)
 404                         break;
 405
 406                 ret = spufs_handle_class0(ctx);
 407                 if (ret)
 408                         break;
 409
 410                 if (signal_pending(current))
 411                         ret = -ERESTARTSYS;
 412         } while (!ret && !(status & (SPU_STATUS_STOPPED_BY_STOP |
 413                                       SPU_STATUS_STOPPED_BY_HALT |
 414                                        SPU_STATUS_SINGLE_STEP)));
 415
 416         spu_disable_spu(ctx);
 417         ret = spu_run_fini(ctx, npc, &status);
 418         spu_yield(ctx);
 419
 420         spu_switch_log_notify(NULL, ctx, SWITCH_LOG_EXIT, status);
 421
 422         if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 423             (((status >> SPU_STOP_STATUS_SHIFT) & 0x3f00) == 0x2100))
 424                 ctx->stats.libassist++;
 425
 426         if ((ret == 0) ||
 427             ((ret == -ERESTARTSYS) &&
 428              ((status & SPU_STATUS_STOPPED_BY_HALT) ||
 429               (status & SPU_STATUS_SINGLE_STEP) ||
 430               ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 431                (status >> SPU_STOP_STATUS_SHIFT != 0x2104)))))
 432                 ret = status;
 433
 434         /* Note: we don't need to force_sig SIGTRAP on single-step
 435          * since we have TIF_SINGLESTEP set, thus the kernel will do
 436          * it upon return from the syscall anyawy
 437          */
 438         if (unlikely(status & SPU_STATUS_SINGLE_STEP))
 439                 ret = -ERESTARTSYS;
 440
 441         else if (unlikely((status & SPU_STATUS_STOPPED_BY_STOP)
 442             && (status >> SPU_STOP_STATUS_SHIFT) == 0x3fff)) {
 443                 force_sig(SIGTRAP, current);
 444                 ret = -ERESTARTSYS;
 445         }
 446
 447 out:
 448         *event = ctx->event_return;
 449 out_unlock:
 450         mutex_unlock(&ctx->run_mutex);
 451         return ret;
 452 }