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)
  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                 ctx->csa.class_0_pending = spu->class_0_pending;
  28                 ctx->csa.dsisr = spu->dsisr;
  29                 ctx->csa.dar = spu->dar;
  30
  31                 /* ensure that the exception status has hit memory before a
  32                  * thread waiting on the context's stop queue is woken */
  33                 smp_wmb();
  34
  35                 wake_up_all(&ctx->stop_wq);
  36         }
  37
  38         /* Clear callback arguments from spu structure */
  39         spu->class_0_pending = 0;
  40         spu->dsisr = 0;
  41         spu->dar = 0;
  42 }
  43
  44 int spu_stopped(struct spu_context *ctx, u32 *stat)
  45 {
  46         u64 dsisr;
  47         u32 stopped;
  48
  49         *stat = ctx->ops->status_read(ctx);
  50
  51         if (test_bit(SPU_SCHED_NOTIFY_ACTIVE, &ctx->sched_flags))
  52                 return 1;
  53
  54         stopped = SPU_STATUS_INVALID_INSTR | SPU_STATUS_SINGLE_STEP |
  55                 SPU_STATUS_STOPPED_BY_HALT | SPU_STATUS_STOPPED_BY_STOP;
  56         if (*stat & stopped)
  57                 return 1;
  58
  59         dsisr = ctx->csa.dsisr;
  60         if (dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED))
  61                 return 1;
  62
  63         if (ctx->csa.class_0_pending)
  64                 return 1;
  65
  66         return 0;
  67 }
  68
  69 static int spu_setup_isolated(struct spu_context *ctx)
  70 {
  71         int ret;
  72         u64 __iomem *mfc_cntl;
  73         u64 sr1;
  74         u32 status;
  75         unsigned long timeout;
  76         const u32 status_loading = SPU_STATUS_RUNNING
  77                 | SPU_STATUS_ISOLATED_STATE | SPU_STATUS_ISOLATED_LOAD_STATUS;
  78
  79         ret = -ENODEV;
  80         if (!isolated_loader)
  81                 goto out;
  82
  83         /*
  84          * We need to exclude userspace access to the context.
  85          *
  86          * To protect against memory access we invalidate all ptes
  87          * and make sure the pagefault handlers block on the mutex.
  88          */
  89         spu_unmap_mappings(ctx);
  90
  91         mfc_cntl = &ctx->spu->priv2->mfc_control_RW;
  92
  93         /* purge the MFC DMA queue to ensure no spurious accesses before we
  94          * enter kernel mode */
  95         timeout = jiffies + HZ;
  96         out_be64(mfc_cntl, MFC_CNTL_PURGE_DMA_REQUEST);
  97         while ((in_be64(mfc_cntl) & MFC_CNTL_PURGE_DMA_STATUS_MASK)
  98                         != MFC_CNTL_PURGE_DMA_COMPLETE) {
  99                 if (time_after(jiffies, timeout)) {
 100                         printk(KERN_ERR "%s: timeout flushing MFC DMA queue\n",
 101                                         __FUNCTION__);
 102                         ret = -EIO;
 103                         goto out;
 104                 }
 105                 cond_resched();
 106         }
 107
 108         /* put the SPE in kernel mode to allow access to the loader */
 109         sr1 = spu_mfc_sr1_get(ctx->spu);
 110         sr1 &= ~MFC_STATE1_PROBLEM_STATE_MASK;
 111         spu_mfc_sr1_set(ctx->spu, sr1);
 112
 113         /* start the loader */
 114         ctx->ops->signal1_write(ctx, (unsigned long)isolated_loader >> 32);
 115         ctx->ops->signal2_write(ctx,
 116                         (unsigned long)isolated_loader & 0xffffffff);
 117
 118         ctx->ops->runcntl_write(ctx,
 119                         SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
 120
 121         ret = 0;
 122         timeout = jiffies + HZ;
 123         while (((status = ctx->ops->status_read(ctx)) & status_loading) ==
 124                                 status_loading) {
 125                 if (time_after(jiffies, timeout)) {
 126                         printk(KERN_ERR "%s: timeout waiting for loader\n",
 127                                         __FUNCTION__);
 128                         ret = -EIO;
 129                         goto out_drop_priv;
 130                 }
 131                 cond_resched();
 132         }
 133
 134         if (!(status & SPU_STATUS_RUNNING)) {
 135                 /* If isolated LOAD has failed: run SPU, we will get a stop-and
 136                  * signal later. */
 137                 pr_debug("%s: isolated LOAD failed\n", __FUNCTION__);
 138                 ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
 139                 ret = -EACCES;
 140                 goto out_drop_priv;
 141         }
 142
 143         if (!(status & SPU_STATUS_ISOLATED_STATE)) {
 144                 /* This isn't allowed by the CBEA, but check anyway */
 145                 pr_debug("%s: SPU fell out of isolated mode?\n", __FUNCTION__);
 146                 ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_STOP);
 147                 ret = -EINVAL;
 148                 goto out_drop_priv;
 149         }
 150
 151 out_drop_priv:
 152         /* Finished accessing the loader. Drop kernel mode */
 153         sr1 |= MFC_STATE1_PROBLEM_STATE_MASK;
 154         spu_mfc_sr1_set(ctx->spu, sr1);
 155
 156 out:
 157         return ret;
 158 }
 159
 160 static int spu_run_init(struct spu_context *ctx, u32 *npc)
 161 {
 162         unsigned long runcntl = SPU_RUNCNTL_RUNNABLE;
 163         int ret;
 164
 165         spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 166
 167         /*
 168          * NOSCHED is synchronous scheduling with respect to the caller.
 169          * The caller waits for the context to be loaded.
 170          */
 171         if (ctx->flags & SPU_CREATE_NOSCHED) {
 172                 if (ctx->state == SPU_STATE_SAVED) {
 173                         ret = spu_activate(ctx, 0);
 174                         if (ret)
 175                                 return ret;
 176                 }
 177         }
 178
 179         /*
 180          * Apply special setup as required.
 181          */
 182         if (ctx->flags & SPU_CREATE_ISOLATE) {
 183                 if (!(ctx->ops->status_read(ctx) & SPU_STATUS_ISOLATED_STATE)) {
 184                         ret = spu_setup_isolated(ctx);
 185                         if (ret)
 186                                 return ret;
 187                 }
 188
 189                 /*
 190                  * If userspace has set the runcntrl register (eg, to
 191                  * issue an isolated exit), we need to re-set it here
 192                  */
 193                 runcntl = ctx->ops->runcntl_read(ctx) &
 194                         (SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
 195                 if (runcntl == 0)
 196                         runcntl = SPU_RUNCNTL_RUNNABLE;
 197         }
 198
 199         if (ctx->flags & SPU_CREATE_NOSCHED) {
 200                 spuctx_switch_state(ctx, SPU_UTIL_USER);
 201                 ctx->ops->runcntl_write(ctx, runcntl);
 202         } else {
 203                 unsigned long privcntl;
 204
 205                 if (test_thread_flag(TIF_SINGLESTEP))
 206                         privcntl = SPU_PRIVCNTL_MODE_SINGLE_STEP;
 207                 else
 208                         privcntl = SPU_PRIVCNTL_MODE_NORMAL;
 209
 210                 ctx->ops->npc_write(ctx, *npc);
 211                 ctx->ops->privcntl_write(ctx, privcntl);
 212                 ctx->ops->runcntl_write(ctx, runcntl);
 213
 214                 if (ctx->state == SPU_STATE_SAVED) {
 215                         ret = spu_activate(ctx, 0);
 216                         if (ret)
 217                                 return ret;
 218                 } else {
 219                         spuctx_switch_state(ctx, SPU_UTIL_USER);
 220                 }
 221         }
 222
 223         return 0;
 224 }
 225
 226 static int spu_run_fini(struct spu_context *ctx, u32 *npc,
 227                                u32 *status)
 228 {
 229         int ret = 0;
 230
 231         spu_del_from_rq(ctx);
 232
 233         *status = ctx->ops->status_read(ctx);
 234         *npc = ctx->ops->npc_read(ctx);
 235
 236         spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
 237         spu_release(ctx);
 238
 239         if (signal_pending(current))
 240                 ret = -ERESTARTSYS;
 241
 242         return ret;
 243 }
 244
 245 /*
 246  * SPU syscall restarting is tricky because we violate the basic
 247  * assumption that the signal handler is running on the interrupted
 248  * thread. Here instead, the handler runs on PowerPC user space code,
 249  * while the syscall was called from the SPU.
 250  * This means we can only do a very rough approximation of POSIX
 251  * signal semantics.
 252  */
 253 static int spu_handle_restartsys(struct spu_context *ctx, long *spu_ret,
 254                           unsigned int *npc)
 255 {
 256         int ret;
 257
 258         switch (*spu_ret) {
 259         case -ERESTARTSYS:
 260         case -ERESTARTNOINTR:
 261                 /*
 262                  * Enter the regular syscall restarting for
 263                  * sys_spu_run, then restart the SPU syscall
 264                  * callback.
 265                  */
 266                 *npc -= 8;
 267                 ret = -ERESTARTSYS;
 268                 break;
 269         case -ERESTARTNOHAND:
 270         case -ERESTART_RESTARTBLOCK:
 271                 /*
 272                  * Restart block is too hard for now, just return -EINTR
 273                  * to the SPU.
 274                  * ERESTARTNOHAND comes from sys_pause, we also return
 275                  * -EINTR from there.
 276                  * Assume that we need to be restarted ourselves though.
 277                  */
 278                 *spu_ret = -EINTR;
 279                 ret = -ERESTARTSYS;
 280                 break;
 281         default:
 282                 printk(KERN_WARNING "%s: unexpected return code %ld\n",
 283                         __FUNCTION__, *spu_ret);
 284                 ret = 0;
 285         }
 286         return ret;
 287 }
 288
 289 static int spu_process_callback(struct spu_context *ctx)
 290 {
 291         struct spu_syscall_block s;
 292         u32 ls_pointer, npc;
 293         void __iomem *ls;
 294         long spu_ret;
 295         int ret, ret2;
 296
 297         /* get syscall block from local store */
 298         npc = ctx->ops->npc_read(ctx) & ~3;
 299         ls = (void __iomem *)ctx->ops->get_ls(ctx);
 300         ls_pointer = in_be32(ls + npc);
 301         if (ls_pointer > (LS_SIZE - sizeof(s)))
 302                 return -EFAULT;
 303         memcpy_fromio(&s, ls + ls_pointer, sizeof(s));
 304
 305         /* do actual syscall without pinning the spu */
 306         ret = 0;
 307         spu_ret = -ENOSYS;
 308         npc += 4;
 309
 310         if (s.nr_ret < __NR_syscalls) {
 311                 spu_release(ctx);
 312                 /* do actual system call from here */
 313                 spu_ret = spu_sys_callback(&s);
 314                 if (spu_ret <= -ERESTARTSYS) {
 315                         ret = spu_handle_restartsys(ctx, &spu_ret, &npc);
 316                 }
 317                 ret2 = spu_acquire(ctx);
 318                 if (ret == -ERESTARTSYS)
 319                         return ret;
 320                 if (ret2)
 321                         return -EINTR;
 322         }
 323
 324         /* write result, jump over indirect pointer */
 325         memcpy_toio(ls + ls_pointer, &spu_ret, sizeof(spu_ret));
 326         ctx->ops->npc_write(ctx, npc);
 327         ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
 328         return ret;
 329 }
 330
 331 long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
 332 {
 333         int ret;
 334         struct spu *spu;
 335         u32 status;
 336
 337         if (mutex_lock_interruptible(&ctx->run_mutex))
 338                 return -ERESTARTSYS;
 339
 340         spu_enable_spu(ctx);
 341         ctx->event_return = 0;
 342
 343         ret = spu_acquire(ctx);
 344         if (ret)
 345                 goto out_unlock;
 346
 347         spu_update_sched_info(ctx);
 348
 349         ret = spu_run_init(ctx, npc);
 350         if (ret) {
 351                 spu_release(ctx);
 352                 goto out;
 353         }
 354
 355         do {
 356                 ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, &status));
 357                 if (unlikely(ret)) {
 358                         /*
 359                          * This is nasty: we need the state_mutex for all the
 360                          * bookkeeping even if the syscall was interrupted by
 361                          * a signal. ewww.
 362                          */
 363                         mutex_lock(&ctx->state_mutex);
 364                         break;
 365                 }
 366                 spu = ctx->spu;
 367                 if (unlikely(test_and_clear_bit(SPU_SCHED_NOTIFY_ACTIVE,
 368                                                 &ctx->sched_flags))) {
 369                         if (!(status & SPU_STATUS_STOPPED_BY_STOP)) {
 370                                 spu_switch_notify(spu, ctx);
 371                                 continue;
 372                         }
 373                 }
 374
 375                 spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 376
 377                 if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 378                     (status >> SPU_STOP_STATUS_SHIFT == 0x2104)) {
 379                         ret = spu_process_callback(ctx);
 380                         if (ret)
 381                                 break;
 382                         status &= ~SPU_STATUS_STOPPED_BY_STOP;
 383                 }
 384                 ret = spufs_handle_class1(ctx);
 385                 if (ret)
 386                         break;
 387
 388                 ret = spufs_handle_class0(ctx);
 389                 if (ret)
 390                         break;
 391
 392                 if (signal_pending(current))
 393                         ret = -ERESTARTSYS;
 394         } while (!ret && !(status & (SPU_STATUS_STOPPED_BY_STOP |
 395                                       SPU_STATUS_STOPPED_BY_HALT |
 396                                        SPU_STATUS_SINGLE_STEP)));
 397
 398         if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 399             (((status >> SPU_STOP_STATUS_SHIFT) & 0x3f00) == 0x2100) &&
 400             (ctx->state == SPU_STATE_RUNNABLE))
 401                 ctx->stats.libassist++;
 402
 403
 404         spu_disable_spu(ctx);
 405         ret = spu_run_fini(ctx, npc, &status);
 406         spu_yield(ctx);
 407
 408         if ((ret == 0) ||
 409             ((ret == -ERESTARTSYS) &&
 410              ((status & SPU_STATUS_STOPPED_BY_HALT) ||
 411               (status & SPU_STATUS_SINGLE_STEP) ||
 412               ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 413                (status >> SPU_STOP_STATUS_SHIFT != 0x2104)))))
 414                 ret = status;
 415
 416         /* Note: we don't need to force_sig SIGTRAP on single-step
 417          * since we have TIF_SINGLESTEP set, thus the kernel will do
 418          * it upon return from the syscall anyawy
 419          */
 420         if (unlikely(status & SPU_STATUS_SINGLE_STEP))
 421                 ret = -ERESTARTSYS;
 422
 423         else if (unlikely((status & SPU_STATUS_STOPPED_BY_STOP)
 424             && (status >> SPU_STOP_STATUS_SHIFT) == 0x3fff)) {
 425                 force_sig(SIGTRAP, current);
 426                 ret = -ERESTARTSYS;
 427         }
 428
 429 out:
 430         *event = ctx->event_return;
 431 out_unlock:
 432         mutex_unlock(&ctx->run_mutex);
 433         return ret;
 434 }