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

   1 /*
   2  * Low-level SPU handling
   3  *
   4  * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
   5  *
   6  * Author: Arnd Bergmann <arndb@de.ibm.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21  */
  22 #include <linux/sched.h>
  23 #include <linux/mm.h>
  24 #include <linux/module.h>
  25
  26 #include <asm/spu.h>
  27 #include <asm/spu_csa.h>
  28
  29 #include "spufs.h"
  30
  31 /**
  32  * Handle an SPE event, depending on context SPU_CREATE_EVENTS_ENABLED flag.
  33  *
  34  * If the context was created with events, we just set the return event.
  35  * Otherwise, send an appropriate signal to the process.
  36  */
  37 static void spufs_handle_event(struct spu_context *ctx,
  38                                 unsigned long ea, int type)
  39 {
  40         siginfo_t info;
  41
  42         if (ctx->flags & SPU_CREATE_EVENTS_ENABLED) {
  43                 ctx->event_return |= type;
  44                 wake_up_all(&ctx->stop_wq);
  45                 return;
  46         }
  47
  48         memset(&info, 0, sizeof(info));
  49
  50         switch (type) {
  51         case SPE_EVENT_INVALID_DMA:
  52                 info.si_signo = SIGBUS;
  53                 info.si_code = BUS_OBJERR;
  54                 break;
  55         case SPE_EVENT_SPE_DATA_STORAGE:
  56                 info.si_signo = SIGSEGV;
  57                 info.si_addr = (void __user *)ea;
  58                 info.si_code = SEGV_ACCERR;
  59                 ctx->ops->restart_dma(ctx);
  60                 break;
  61         case SPE_EVENT_DMA_ALIGNMENT:
  62                 info.si_signo = SIGBUS;
  63                 /* DAR isn't set for an alignment fault :( */
  64                 info.si_code = BUS_ADRALN;
  65                 break;
  66         case SPE_EVENT_SPE_ERROR:
  67                 info.si_signo = SIGILL;
  68                 info.si_addr = (void __user *)(unsigned long)
  69                         ctx->ops->npc_read(ctx) - 4;
  70                 info.si_code = ILL_ILLOPC;
  71                 break;
  72         }
  73
  74         if (info.si_signo)
  75                 force_sig_info(info.si_signo, &info, current);
  76 }
  77
  78 int spufs_handle_class0(struct spu_context *ctx)
  79 {
  80         unsigned long stat = ctx->csa.class_0_pending & CLASS0_INTR_MASK;
  81
  82         if (likely(!stat))
  83                 return 0;
  84
  85         if (stat & CLASS0_DMA_ALIGNMENT_INTR)
  86                 spufs_handle_event(ctx, ctx->csa.dar, SPE_EVENT_DMA_ALIGNMENT);
  87
  88         if (stat & CLASS0_INVALID_DMA_COMMAND_INTR)
  89                 spufs_handle_event(ctx, ctx->csa.dar, SPE_EVENT_INVALID_DMA);
  90
  91         if (stat & CLASS0_SPU_ERROR_INTR)
  92                 spufs_handle_event(ctx, ctx->csa.dar, SPE_EVENT_SPE_ERROR);
  93
  94         return -EIO;
  95 }
  96
  97 /*
  98  * bottom half handler for page faults, we can't do this from
  99  * interrupt context, since we might need to sleep.
 100  * we also need to give up the mutex so we can get scheduled
 101  * out while waiting for the backing store.
 102  *
 103  * TODO: try calling hash_page from the interrupt handler first
 104  *       in order to speed up the easy case.
 105  */
 106 int spufs_handle_class1(struct spu_context *ctx)
 107 {
 108         u64 ea, dsisr, access;
 109         unsigned long flags;
 110         unsigned flt = 0;
 111         int ret;
 112
 113         /*
 114          * dar and dsisr get passed from the registers
 115          * to the spu_context, to this function, but not
 116          * back to the spu if it gets scheduled again.
 117          *
 118          * if we don't handle the fault for a saved context
 119          * in time, we can still expect to get the same fault
 120          * the immediately after the context restore.
 121          */
 122         ea = ctx->csa.dar;
 123         dsisr = ctx->csa.dsisr;
 124
 125         if (!(dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED)))
 126                 return 0;
 127
 128         spuctx_switch_state(ctx, SPU_UTIL_IOWAIT);
 129
 130         pr_debug("ctx %p: ea %016lx, dsisr %016lx state %d\n", ctx, ea,
 131                 dsisr, ctx->state);
 132
 133         ctx->stats.hash_flt++;
 134         if (ctx->state == SPU_STATE_RUNNABLE)
 135                 ctx->spu->stats.hash_flt++;
 136
 137         /* we must not hold the lock when entering spu_handle_mm_fault */
 138         spu_release(ctx);
 139
 140         access = (_PAGE_PRESENT | _PAGE_USER);
 141         access |= (dsisr & MFC_DSISR_ACCESS_PUT) ? _PAGE_RW : 0UL;
 142         local_irq_save(flags);
 143         ret = hash_page(ea, access, 0x300);
 144         local_irq_restore(flags);
 145
 146         /* hashing failed, so try the actual fault handler */
 147         if (ret)
 148                 ret = spu_handle_mm_fault(current->mm, ea, dsisr, &flt);
 149
 150         /*
 151          * This is nasty: we need the state_mutex for all the bookkeeping even
 152          * if the syscall was interrupted by a signal. ewww.
 153          */
 154         mutex_lock(&ctx->state_mutex);
 155
 156         /*
 157          * Clear dsisr under ctxt lock after handling the fault, so that
 158          * time slicing will not preempt the context while the page fault
 159          * handler is running. Context switch code removes mappings.
 160          */
 161         ctx->csa.dar = ctx->csa.dsisr = 0;
 162
 163         /*
 164          * If we handled the fault successfully and are in runnable
 165          * state, restart the DMA.
 166          * In case of unhandled error report the problem to user space.
 167          */
 168         if (!ret) {
 169                 if (flt & VM_FAULT_MAJOR)
 170                         ctx->stats.maj_flt++;
 171                 else
 172                         ctx->stats.min_flt++;
 173                 if (ctx->state == SPU_STATE_RUNNABLE) {
 174                         if (flt & VM_FAULT_MAJOR)
 175                                 ctx->spu->stats.maj_flt++;
 176                         else
 177                                 ctx->spu->stats.min_flt++;
 178                 }
 179
 180                 if (ctx->spu)
 181                         ctx->ops->restart_dma(ctx);
 182         } else
 183                 spufs_handle_event(ctx, ea, SPE_EVENT_SPE_DATA_STORAGE);
 184
 185         spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 186         return ret;
 187 }