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 static inline int spu_stopped(struct spu_context *ctx, u32 *stat)
  45 {
  46         struct spu *spu;
  47         u64 pte_fault;
  48
  49         *stat = ctx->ops->status_read(ctx);
  50
  51         spu = ctx->spu;
  52         if (ctx->state != SPU_STATE_RUNNABLE ||
  53             test_bit(SPU_SCHED_NOTIFY_ACTIVE, &ctx->sched_flags))
  54                 return 1;
  55         pte_fault = ctx->csa.dsisr &
  56             (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED);
  57         return (!(*stat & SPU_STATUS_RUNNING) || pte_fault || ctx->csa.class_0_pending) ?
  58                 1 : 0;
  59 }
  60
  61 static int spu_setup_isolated(struct spu_context *ctx)
  62 {
  63         int ret;
  64         u64 __iomem *mfc_cntl;
  65         u64 sr1;
  66         u32 status;
  67         unsigned long timeout;
  68         const u32 status_loading = SPU_STATUS_RUNNING
  69                 | SPU_STATUS_ISOLATED_STATE | SPU_STATUS_ISOLATED_LOAD_STATUS;
  70
  71         ret = -ENODEV;
  72         if (!isolated_loader)
  73                 goto out;
  74
  75         /*
  76          * We need to exclude userspace access to the context.
  77          *
  78          * To protect against memory access we invalidate all ptes
  79          * and make sure the pagefault handlers block on the mutex.
  80          */
  81         spu_unmap_mappings(ctx);
  82
  83         mfc_cntl = &ctx->spu->priv2->mfc_control_RW;
  84
  85         /* purge the MFC DMA queue to ensure no spurious accesses before we
  86          * enter kernel mode */
  87         timeout = jiffies + HZ;
  88         out_be64(mfc_cntl, MFC_CNTL_PURGE_DMA_REQUEST);
  89         while ((in_be64(mfc_cntl) & MFC_CNTL_PURGE_DMA_STATUS_MASK)
  90                         != MFC_CNTL_PURGE_DMA_COMPLETE) {
  91                 if (time_after(jiffies, timeout)) {
  92                         printk(KERN_ERR "%s: timeout flushing MFC DMA queue\n",
  93                                         __FUNCTION__);
  94                         ret = -EIO;
  95                         goto out;
  96                 }
  97                 cond_resched();
  98         }
  99
 100         /* put the SPE in kernel mode to allow access to the loader */
 101         sr1 = spu_mfc_sr1_get(ctx->spu);
 102         sr1 &= ~MFC_STATE1_PROBLEM_STATE_MASK;
 103         spu_mfc_sr1_set(ctx->spu, sr1);
 104
 105         /* start the loader */
 106         ctx->ops->signal1_write(ctx, (unsigned long)isolated_loader >> 32);
 107         ctx->ops->signal2_write(ctx,
 108                         (unsigned long)isolated_loader & 0xffffffff);
 109
 110         ctx->ops->runcntl_write(ctx,
 111                         SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
 112
 113         ret = 0;
 114         timeout = jiffies + HZ;
 115         while (((status = ctx->ops->status_read(ctx)) & status_loading) ==
 116                                 status_loading) {
 117                 if (time_after(jiffies, timeout)) {
 118                         printk(KERN_ERR "%s: timeout waiting for loader\n",
 119                                         __FUNCTION__);
 120                         ret = -EIO;
 121                         goto out_drop_priv;
 122                 }
 123                 cond_resched();
 124         }
 125
 126         if (!(status & SPU_STATUS_RUNNING)) {
 127                 /* If isolated LOAD has failed: run SPU, we will get a stop-and
 128                  * signal later. */
 129                 pr_debug("%s: isolated LOAD failed\n", __FUNCTION__);
 130                 ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
 131                 ret = -EACCES;
 132                 goto out_drop_priv;
 133         }
 134
 135         if (!(status & SPU_STATUS_ISOLATED_STATE)) {
 136                 /* This isn't allowed by the CBEA, but check anyway */
 137                 pr_debug("%s: SPU fell out of isolated mode?\n", __FUNCTION__);
 138                 ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_STOP);
 139                 ret = -EINVAL;
 140                 goto out_drop_priv;
 141         }
 142
 143 out_drop_priv:
 144         /* Finished accessing the loader. Drop kernel mode */
 145         sr1 |= MFC_STATE1_PROBLEM_STATE_MASK;
 146         spu_mfc_sr1_set(ctx->spu, sr1);
 147
 148 out:
 149         return ret;
 150 }
 151
 152 static int spu_run_init(struct spu_context *ctx, u32 *npc)
 153 {
 154         unsigned long runcntl;
 155         int ret;
 156
 157         spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 158
 159         if (ctx->flags & SPU_CREATE_ISOLATE) {
 160                 /*
 161                  * Force activation of spu.  Isolated state assumes that
 162                  * special loader context is loaded and running on spu.
 163                  */
 164                 if (ctx->state == SPU_STATE_SAVED) {
 165                         spu_set_timeslice(ctx);
 166
 167                         ret = spu_activate(ctx, 0);
 168                         if (ret)
 169                                 return ret;
 170                 }
 171
 172                 if (!(ctx->ops->status_read(ctx) & SPU_STATUS_ISOLATED_STATE)) {
 173                         ret = spu_setup_isolated(ctx);
 174                         if (ret)
 175                                 return ret;
 176                 }
 177
 178                 /*
 179                  * If userspace has set the runcntrl register (eg, to
 180                  * issue an isolated exit), we need to re-set it here
 181                  */
 182                 runcntl = ctx->ops->runcntl_read(ctx) &
 183                         (SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
 184                 if (runcntl == 0)
 185                         runcntl = SPU_RUNCNTL_RUNNABLE;
 186
 187                 spuctx_switch_state(ctx, SPU_UTIL_USER);
 188                 ctx->ops->runcntl_write(ctx, runcntl);
 189
 190         } else {
 191                 unsigned long privcntl;
 192
 193                 if (test_thread_flag(TIF_SINGLESTEP))
 194                         privcntl = SPU_PRIVCNTL_MODE_SINGLE_STEP;
 195                 else
 196                         privcntl = SPU_PRIVCNTL_MODE_NORMAL;
 197                 runcntl = SPU_RUNCNTL_RUNNABLE;
 198
 199                 ctx->ops->npc_write(ctx, *npc);
 200                 ctx->ops->privcntl_write(ctx, privcntl);
 201
 202                 if (ctx->state == SPU_STATE_SAVED) {
 203                         spu_set_timeslice(ctx);
 204                         ret = spu_activate(ctx, 0);
 205                         if (ret)
 206                                 return ret;
 207                 }
 208
 209                 spuctx_switch_state(ctx, SPU_UTIL_USER);
 210                 ctx->ops->runcntl_write(ctx, runcntl);
 211         }
 212
 213         return 0;
 214 }
 215
 216 static int spu_run_fini(struct spu_context *ctx, u32 *npc,
 217                                u32 *status)
 218 {
 219         int ret = 0;
 220
 221         *status = ctx->ops->status_read(ctx);
 222         *npc = ctx->ops->npc_read(ctx);
 223
 224         spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
 225         spu_release(ctx);
 226
 227         if (signal_pending(current))
 228                 ret = -ERESTARTSYS;
 229
 230         return ret;
 231 }
 232
 233 static int spu_reacquire_runnable(struct spu_context *ctx, u32 *npc,
 234                                          u32 *status)
 235 {
 236         int ret;
 237
 238         ret = spu_run_fini(ctx, npc, status);
 239         if (ret)
 240                 return ret;
 241
 242         if (*status & (SPU_STATUS_STOPPED_BY_STOP | SPU_STATUS_STOPPED_BY_HALT))
 243                 return *status;
 244
 245         ret = spu_acquire_runnable(ctx, 0);
 246         if (ret)
 247                 return ret;
 248
 249         spuctx_switch_state(ctx, SPU_UTIL_USER);
 250         return 0;
 251 }
 252
 253 /*
 254  * SPU syscall restarting is tricky because we violate the basic
 255  * assumption that the signal handler is running on the interrupted
 256  * thread. Here instead, the handler runs on PowerPC user space code,
 257  * while the syscall was called from the SPU.
 258  * This means we can only do a very rough approximation of POSIX
 259  * signal semantics.
 260  */
 261 static int spu_handle_restartsys(struct spu_context *ctx, long *spu_ret,
 262                           unsigned int *npc)
 263 {
 264         int ret;
 265
 266         switch (*spu_ret) {
 267         case -ERESTARTSYS:
 268         case -ERESTARTNOINTR:
 269                 /*
 270                  * Enter the regular syscall restarting for
 271                  * sys_spu_run, then restart the SPU syscall
 272                  * callback.
 273                  */
 274                 *npc -= 8;
 275                 ret = -ERESTARTSYS;
 276                 break;
 277         case -ERESTARTNOHAND:
 278         case -ERESTART_RESTARTBLOCK:
 279                 /*
 280                  * Restart block is too hard for now, just return -EINTR
 281                  * to the SPU.
 282                  * ERESTARTNOHAND comes from sys_pause, we also return
 283                  * -EINTR from there.
 284                  * Assume that we need to be restarted ourselves though.
 285                  */
 286                 *spu_ret = -EINTR;
 287                 ret = -ERESTARTSYS;
 288                 break;
 289         default:
 290                 printk(KERN_WARNING "%s: unexpected return code %ld\n",
 291                         __FUNCTION__, *spu_ret);
 292                 ret = 0;
 293         }
 294         return ret;
 295 }
 296
 297 static int spu_process_callback(struct spu_context *ctx)
 298 {
 299         struct spu_syscall_block s;
 300         u32 ls_pointer, npc;
 301         void __iomem *ls;
 302         long spu_ret;
 303         int ret;
 304
 305         /* get syscall block from local store */
 306         npc = ctx->ops->npc_read(ctx) & ~3;
 307         ls = (void __iomem *)ctx->ops->get_ls(ctx);
 308         ls_pointer = in_be32(ls + npc);
 309         if (ls_pointer > (LS_SIZE - sizeof(s)))
 310                 return -EFAULT;
 311         memcpy_fromio(&s, ls + ls_pointer, sizeof(s));
 312
 313         /* do actual syscall without pinning the spu */
 314         ret = 0;
 315         spu_ret = -ENOSYS;
 316         npc += 4;
 317
 318         if (s.nr_ret < __NR_syscalls) {
 319                 spu_release(ctx);
 320                 /* do actual system call from here */
 321                 spu_ret = spu_sys_callback(&s);
 322                 if (spu_ret <= -ERESTARTSYS) {
 323                         ret = spu_handle_restartsys(ctx, &spu_ret, &npc);
 324                 }
 325                 spu_acquire(ctx);
 326                 if (ret == -ERESTARTSYS)
 327                         return ret;
 328         }
 329
 330         /* write result, jump over indirect pointer */
 331         memcpy_toio(ls + ls_pointer, &spu_ret, sizeof(spu_ret));
 332         ctx->ops->npc_write(ctx, npc);
 333         ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
 334         return ret;
 335 }
 336
 337 long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
 338 {
 339         int ret;
 340         struct spu *spu;
 341         u32 status;
 342
 343         if (mutex_lock_interruptible(&ctx->run_mutex))
 344                 return -ERESTARTSYS;
 345
 346         spu_enable_spu(ctx);
 347         ctx->event_return = 0;
 348
 349         spu_acquire(ctx);
 350
 351         spu_update_sched_info(ctx);
 352
 353         ret = spu_run_init(ctx, npc);
 354         if (ret) {
 355                 spu_release(ctx);
 356                 goto out;
 357         }
 358
 359         do {
 360                 ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, &status));
 361                 if (unlikely(ret))
 362                         break;
 363                 spu = ctx->spu;
 364                 if (unlikely(test_and_clear_bit(SPU_SCHED_NOTIFY_ACTIVE,
 365                                                 &ctx->sched_flags))) {
 366                         if (!(status & SPU_STATUS_STOPPED_BY_STOP)) {
 367                                 spu_switch_notify(spu, ctx);
 368                                 continue;
 369                         }
 370                 }
 371
 372                 spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 373
 374                 if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 375                     (status >> SPU_STOP_STATUS_SHIFT == 0x2104)) {
 376                         ret = spu_process_callback(ctx);
 377                         if (ret)
 378                                 break;
 379                         status &= ~SPU_STATUS_STOPPED_BY_STOP;
 380                 }
 381                 ret = spufs_handle_class1(ctx);
 382                 if (ret)
 383                         break;
 384
 385                 ret = spufs_handle_class0(ctx);
 386                 if (ret)
 387                         break;
 388
 389                 if (unlikely(ctx->state != SPU_STATE_RUNNABLE)) {
 390                         ret = spu_reacquire_runnable(ctx, npc, &status);
 391                         if (ret)
 392                                 goto out2;
 393                         continue;
 394                 }
 395
 396                 if (signal_pending(current))
 397                         ret = -ERESTARTSYS;
 398
 399
 400         } while (!ret && !(status & (SPU_STATUS_STOPPED_BY_STOP |
 401                                       SPU_STATUS_STOPPED_BY_HALT |
 402                                        SPU_STATUS_SINGLE_STEP)));
 403
 404         if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 405             (((status >> SPU_STOP_STATUS_SHIFT) & 0x3f00) == 0x2100) &&
 406             (ctx->state == SPU_STATE_RUNNABLE))
 407                 ctx->stats.libassist++;
 408
 409
 410         spu_disable_spu(ctx);
 411         ret = spu_run_fini(ctx, npc, &status);
 412         spu_yield(ctx);
 413
 414 out2:
 415         if ((ret == 0) ||
 416             ((ret == -ERESTARTSYS) &&
 417              ((status & SPU_STATUS_STOPPED_BY_HALT) ||
 418               (status & SPU_STATUS_SINGLE_STEP) ||
 419               ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 420                (status >> SPU_STOP_STATUS_SHIFT != 0x2104)))))
 421                 ret = status;
 422
 423         /* Note: we don't need to force_sig SIGTRAP on single-step
 424          * since we have TIF_SINGLESTEP set, thus the kernel will do
 425          * it upon return from the syscall anyawy
 426          */
 427         if ((status & SPU_STATUS_STOPPED_BY_STOP)
 428             && (status >> SPU_STOP_STATUS_SHIFT) == 0x3fff) {
 429                 force_sig(SIGTRAP, current);
 430                 ret = -ERESTARTSYS;
 431         }
 432
 433 out:
 434         *event = ctx->event_return;
 435         mutex_unlock(&ctx->run_mutex);
 436         return ret;
 437 }