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

   1 // SPDX-License-Identifier: GPL-2.0
   2 #define DEBUG
   3
   4 #include <linux/wait.h>
   5 #include <linux/ptrace.h>
   6
   7 #include <asm/spu.h>
   8 #include <asm/spu_priv1.h>
   9 #include <asm/io.h>
  10 #include <asm/unistd.h>
  11
  12 #include "spufs.h"
  13
  14 /* interrupt-level stop callback function. */
  15 void spufs_stop_callback(struct spu *spu, int irq)
  16 {
  17         struct spu_context *ctx = spu->ctx;
  18
  19         /*
  20          * It should be impossible to preempt a context while an exception
  21          * is being processed, since the context switch code is specially
  22          * coded to deal with interrupts ... But, just in case, sanity check
  23          * the context pointer.  It is OK to return doing nothing since
  24          * the exception will be regenerated when the context is resumed.
  25          */
  26         if (ctx) {
  27                 /* Copy exception arguments into module specific structure */
  28                 switch(irq) {
  29                 case 0 :
  30                         ctx->csa.class_0_pending = spu->class_0_pending;
  31                         ctx->csa.class_0_dar = spu->class_0_dar;
  32                         break;
  33                 case 1 :
  34                         ctx->csa.class_1_dsisr = spu->class_1_dsisr;
  35                         ctx->csa.class_1_dar = spu->class_1_dar;
  36                         break;
  37                 case 2 :
  38                         break;
  39                 }
  40
  41                 /* ensure that the exception status has hit memory before a
  42                  * thread waiting on the context's stop queue is woken */
  43                 smp_wmb();
  44
  45                 wake_up_all(&ctx->stop_wq);
  46         }
  47 }
  48
  49 int spu_stopped(struct spu_context *ctx, u32 *stat)
  50 {
  51         u64 dsisr;
  52         u32 stopped;
  53
  54         stopped = SPU_STATUS_INVALID_INSTR | SPU_STATUS_SINGLE_STEP |
  55                 SPU_STATUS_STOPPED_BY_HALT | SPU_STATUS_STOPPED_BY_STOP;
  56
  57 top:
  58         *stat = ctx->ops->status_read(ctx);
  59         if (*stat & stopped) {
  60                 /*
  61                  * If the spu hasn't finished stopping, we need to
  62                  * re-read the register to get the stopped value.
  63                  */
  64                 if (*stat & SPU_STATUS_RUNNING)
  65                         goto top;
  66                 return 1;
  67         }
  68
  69         if (test_bit(SPU_SCHED_NOTIFY_ACTIVE, &ctx->sched_flags))
  70                 return 1;
  71
  72         dsisr = ctx->csa.class_1_dsisr;
  73         if (dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED))
  74                 return 1;
  75
  76         if (ctx->csa.class_0_pending)
  77                 return 1;
  78
  79         return 0;
  80 }
  81
  82 static int spu_setup_isolated(struct spu_context *ctx)
  83 {
  84         int ret;
  85         u64 __iomem *mfc_cntl;
  86         u64 sr1;
  87         u32 status;
  88         unsigned long timeout;
  89         const u32 status_loading = SPU_STATUS_RUNNING
  90                 | SPU_STATUS_ISOLATED_STATE | SPU_STATUS_ISOLATED_LOAD_STATUS;
  91
  92         ret = -ENODEV;
  93         if (!isolated_loader)
  94                 goto out;
  95
  96         /*
  97          * We need to exclude userspace access to the context.
  98          *
  99          * To protect against memory access we invalidate all ptes
 100          * and make sure the pagefault handlers block on the mutex.
 101          */
 102         spu_unmap_mappings(ctx);
 103
 104         mfc_cntl = &ctx->spu->priv2->mfc_control_RW;
 105
 106         /* purge the MFC DMA queue to ensure no spurious accesses before we
 107          * enter kernel mode */
 108         timeout = jiffies + HZ;
 109         out_be64(mfc_cntl, MFC_CNTL_PURGE_DMA_REQUEST);
 110         while ((in_be64(mfc_cntl) & MFC_CNTL_PURGE_DMA_STATUS_MASK)
 111                         != MFC_CNTL_PURGE_DMA_COMPLETE) {
 112                 if (time_after(jiffies, timeout)) {
 113                         printk(KERN_ERR "%s: timeout flushing MFC DMA queue\n",
 114                                         __func__);
 115                         ret = -EIO;
 116                         goto out;
 117                 }
 118                 cond_resched();
 119         }
 120
 121         /* clear purge status */
 122         out_be64(mfc_cntl, 0);
 123
 124         /* put the SPE in kernel mode to allow access to the loader */
 125         sr1 = spu_mfc_sr1_get(ctx->spu);
 126         sr1 &= ~MFC_STATE1_PROBLEM_STATE_MASK;
 127         spu_mfc_sr1_set(ctx->spu, sr1);
 128
 129         /* start the loader */
 130         ctx->ops->signal1_write(ctx, (unsigned long)isolated_loader >> 32);
 131         ctx->ops->signal2_write(ctx,
 132                         (unsigned long)isolated_loader & 0xffffffff);
 133
 134         ctx->ops->runcntl_write(ctx,
 135                         SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
 136
 137         ret = 0;
 138         timeout = jiffies + HZ;
 139         while (((status = ctx->ops->status_read(ctx)) & status_loading) ==
 140                                 status_loading) {
 141                 if (time_after(jiffies, timeout)) {
 142                         printk(KERN_ERR "%s: timeout waiting for loader\n",
 143                                         __func__);
 144                         ret = -EIO;
 145                         goto out_drop_priv;
 146                 }
 147                 cond_resched();
 148         }
 149
 150         if (!(status & SPU_STATUS_RUNNING)) {
 151                 /* If isolated LOAD has failed: run SPU, we will get a stop-and
 152                  * signal later. */
 153                 pr_debug("%s: isolated LOAD failed\n", __func__);
 154                 ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
 155                 ret = -EACCES;
 156                 goto out_drop_priv;
 157         }
 158
 159         if (!(status & SPU_STATUS_ISOLATED_STATE)) {
 160                 /* This isn't allowed by the CBEA, but check anyway */
 161                 pr_debug("%s: SPU fell out of isolated mode?\n", __func__);
 162                 ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_STOP);
 163                 ret = -EINVAL;
 164                 goto out_drop_priv;
 165         }
 166
 167 out_drop_priv:
 168         /* Finished accessing the loader. Drop kernel mode */
 169         sr1 |= MFC_STATE1_PROBLEM_STATE_MASK;
 170         spu_mfc_sr1_set(ctx->spu, sr1);
 171
 172 out:
 173         return ret;
 174 }
 175
 176 static int spu_run_init(struct spu_context *ctx, u32 *npc)
 177 {
 178         unsigned long runcntl = SPU_RUNCNTL_RUNNABLE;
 179         int ret;
 180
 181         spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 182
 183         /*
 184          * NOSCHED is synchronous scheduling with respect to the caller.
 185          * The caller waits for the context to be loaded.
 186          */
 187         if (ctx->flags & SPU_CREATE_NOSCHED) {
 188                 if (ctx->state == SPU_STATE_SAVED) {
 189                         ret = spu_activate(ctx, 0);
 190                         if (ret)
 191                                 return ret;
 192                 }
 193         }
 194
 195         /*
 196          * Apply special setup as required.
 197          */
 198         if (ctx->flags & SPU_CREATE_ISOLATE) {
 199                 if (!(ctx->ops->status_read(ctx) & SPU_STATUS_ISOLATED_STATE)) {
 200                         ret = spu_setup_isolated(ctx);
 201                         if (ret)
 202                                 return ret;
 203                 }
 204
 205                 /*
 206                  * If userspace has set the runcntrl register (eg, to
 207                  * issue an isolated exit), we need to re-set it here
 208                  */
 209                 runcntl = ctx->ops->runcntl_read(ctx) &
 210                         (SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
 211                 if (runcntl == 0)
 212                         runcntl = SPU_RUNCNTL_RUNNABLE;
 213         } else {
 214                 unsigned long privcntl;
 215
 216                 if (test_thread_flag(TIF_SINGLESTEP))
 217                         privcntl = SPU_PRIVCNTL_MODE_SINGLE_STEP;
 218                 else
 219                         privcntl = SPU_PRIVCNTL_MODE_NORMAL;
 220
 221                 ctx->ops->privcntl_write(ctx, privcntl);
 222                 ctx->ops->npc_write(ctx, *npc);
 223         }
 224
 225         ctx->ops->runcntl_write(ctx, runcntl);
 226
 227         if (ctx->flags & SPU_CREATE_NOSCHED) {
 228                 spuctx_switch_state(ctx, SPU_UTIL_USER);
 229         } else {
 230
 231                 if (ctx->state == SPU_STATE_SAVED) {
 232                         ret = spu_activate(ctx, 0);
 233                         if (ret)
 234                                 return ret;
 235                 } else {
 236                         spuctx_switch_state(ctx, SPU_UTIL_USER);
 237                 }
 238         }
 239
 240         set_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags);
 241         return 0;
 242 }
 243
 244 static int spu_run_fini(struct spu_context *ctx, u32 *npc,
 245                                u32 *status)
 246 {
 247         int ret = 0;
 248
 249         spu_del_from_rq(ctx);
 250
 251         *status = ctx->ops->status_read(ctx);
 252         *npc = ctx->ops->npc_read(ctx);
 253
 254         spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
 255         clear_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags);
 256         spu_switch_log_notify(NULL, ctx, SWITCH_LOG_EXIT, *status);
 257         spu_release(ctx);
 258
 259         if (signal_pending(current))
 260                 ret = -ERESTARTSYS;
 261
 262         return ret;
 263 }
 264
 265 /*
 266  * SPU syscall restarting is tricky because we violate the basic
 267  * assumption that the signal handler is running on the interrupted
 268  * thread. Here instead, the handler runs on PowerPC user space code,
 269  * while the syscall was called from the SPU.
 270  * This means we can only do a very rough approximation of POSIX
 271  * signal semantics.
 272  */
 273 static int spu_handle_restartsys(struct spu_context *ctx, long *spu_ret,
 274                           unsigned int *npc)
 275 {
 276         int ret;
 277
 278         switch (*spu_ret) {
 279         case -ERESTARTSYS:
 280         case -ERESTARTNOINTR:
 281                 /*
 282                  * Enter the regular syscall restarting for
 283                  * sys_spu_run, then restart the SPU syscall
 284                  * callback.
 285                  */
 286                 *npc -= 8;
 287                 ret = -ERESTARTSYS;
 288                 break;
 289         case -ERESTARTNOHAND:
 290         case -ERESTART_RESTARTBLOCK:
 291                 /*
 292                  * Restart block is too hard for now, just return -EINTR
 293                  * to the SPU.
 294                  * ERESTARTNOHAND comes from sys_pause, we also return
 295                  * -EINTR from there.
 296                  * Assume that we need to be restarted ourselves though.
 297                  */
 298                 *spu_ret = -EINTR;
 299                 ret = -ERESTARTSYS;
 300                 break;
 301         default:
 302                 printk(KERN_WARNING "%s: unexpected return code %ld\n",
 303                         __func__, *spu_ret);
 304                 ret = 0;
 305         }
 306         return ret;
 307 }
 308
 309 static int spu_process_callback(struct spu_context *ctx)
 310 {
 311         struct spu_syscall_block s;
 312         u32 ls_pointer, npc;
 313         void __iomem *ls;
 314         long spu_ret;
 315         int ret;
 316
 317         /* get syscall block from local store */
 318         npc = ctx->ops->npc_read(ctx) & ~3;
 319         ls = (void __iomem *)ctx->ops->get_ls(ctx);
 320         ls_pointer = in_be32(ls + npc);
 321         if (ls_pointer > (LS_SIZE - sizeof(s)))
 322                 return -EFAULT;
 323         memcpy_fromio(&s, ls + ls_pointer, sizeof(s));
 324
 325         /* do actual syscall without pinning the spu */
 326         ret = 0;
 327         spu_ret = -ENOSYS;
 328         npc += 4;
 329
 330         if (s.nr_ret < NR_syscalls) {
 331                 spu_release(ctx);
 332                 /* do actual system call from here */
 333                 spu_ret = spu_sys_callback(&s);
 334                 if (spu_ret <= -ERESTARTSYS) {
 335                         ret = spu_handle_restartsys(ctx, &spu_ret, &npc);
 336                 }
 337                 mutex_lock(&ctx->state_mutex);
 338                 if (ret == -ERESTARTSYS)
 339                         return ret;
 340         }
 341
 342         /* need to re-get the ls, as it may have changed when we released the
 343          * spu */
 344         ls = (void __iomem *)ctx->ops->get_ls(ctx);
 345
 346         /* write result, jump over indirect pointer */
 347         memcpy_toio(ls + ls_pointer, &spu_ret, sizeof(spu_ret));
 348         ctx->ops->npc_write(ctx, npc);
 349         ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
 350         return ret;
 351 }
 352
 353 long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
 354 {
 355         int ret;
 356         struct spu *spu;
 357         u32 status;
 358
 359         if (mutex_lock_interruptible(&ctx->run_mutex))
 360                 return -ERESTARTSYS;
 361
 362         ctx->event_return = 0;
 363
 364         ret = spu_acquire(ctx);
 365         if (ret)
 366                 goto out_unlock;
 367
 368         spu_enable_spu(ctx);
 369
 370         spu_update_sched_info(ctx);
 371
 372         ret = spu_run_init(ctx, npc);
 373         if (ret) {
 374                 spu_release(ctx);
 375                 goto out;
 376         }
 377
 378         do {
 379                 ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, &status));
 380                 if (unlikely(ret)) {
 381                         /*
 382                          * This is nasty: we need the state_mutex for all the
 383                          * bookkeeping even if the syscall was interrupted by
 384                          * a signal. ewww.
 385                          */
 386                         mutex_lock(&ctx->state_mutex);
 387                         break;
 388                 }
 389                 spu = ctx->spu;
 390                 if (unlikely(test_and_clear_bit(SPU_SCHED_NOTIFY_ACTIVE,
 391                                                 &ctx->sched_flags))) {
 392                         if (!(status & SPU_STATUS_STOPPED_BY_STOP)) {
 393                                 spu_switch_notify(spu, ctx);
 394                                 continue;
 395                         }
 396                 }
 397
 398                 spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 399
 400                 if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 401                     (status >> SPU_STOP_STATUS_SHIFT == 0x2104)) {
 402                         ret = spu_process_callback(ctx);
 403                         if (ret)
 404                                 break;
 405                         status &= ~SPU_STATUS_STOPPED_BY_STOP;
 406                 }
 407                 ret = spufs_handle_class1(ctx);
 408                 if (ret)
 409                         break;
 410
 411                 ret = spufs_handle_class0(ctx);
 412                 if (ret)
 413                         break;
 414
 415                 if (signal_pending(current))
 416                         ret = -ERESTARTSYS;
 417         } while (!ret && !(status & (SPU_STATUS_STOPPED_BY_STOP |
 418                                       SPU_STATUS_STOPPED_BY_HALT |
 419                                        SPU_STATUS_SINGLE_STEP)));
 420
 421         spu_disable_spu(ctx);
 422         ret = spu_run_fini(ctx, npc, &status);
 423         spu_yield(ctx);
 424
 425         if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 426             (((status >> SPU_STOP_STATUS_SHIFT) & 0x3f00) == 0x2100))
 427                 ctx->stats.libassist++;
 428
 429         if ((ret == 0) ||
 430             ((ret == -ERESTARTSYS) &&
 431              ((status & SPU_STATUS_STOPPED_BY_HALT) ||
 432               (status & SPU_STATUS_SINGLE_STEP) ||
 433               ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 434                (status >> SPU_STOP_STATUS_SHIFT != 0x2104)))))
 435                 ret = status;
 436
 437         /* Note: we don't need to force_sig SIGTRAP on single-step
 438          * since we have TIF_SINGLESTEP set, thus the kernel will do
 439          * it upon return from the syscall anyway.
 440          */
 441         if (unlikely(status & SPU_STATUS_SINGLE_STEP))
 442                 ret = -ERESTARTSYS;
 443
 444         else if (unlikely((status & SPU_STATUS_STOPPED_BY_STOP)
 445             && (status >> SPU_STOP_STATUS_SHIFT) == 0x3fff)) {
 446                 force_sig(SIGTRAP);
 447                 ret = -ERESTARTSYS;
 448         }
 449
 450 out:
 451         *event = ctx->event_return;
 452 out_unlock:
 453         mutex_unlock(&ctx->run_mutex);
 454         return ret;
 455 }