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
  25 #include <asm/spu.h>
  26 #include <asm/spu_csa.h>
  27
  28 #include "spufs.h"
  29
  30 /**
  31  * Handle an SPE event, depending on context SPU_CREATE_EVENTS_ENABLED flag.
  32  *
  33  * If the context was created with events, we just set the return event.
  34  * Otherwise, send an appropriate signal to the process.
  35  */
  36 static void spufs_handle_event(struct spu_context *ctx,
  37                                 unsigned long ea, int type)
  38 {
  39         siginfo_t info;
  40
  41         if (ctx->flags & SPU_CREATE_EVENTS_ENABLED) {
  42                 ctx->event_return |= type;
  43                 wake_up_all(&ctx->stop_wq);
  44                 return;
  45         }
  46
  47         memset(&info, 0, sizeof(info));
  48
  49         switch (type) {
  50         case SPE_EVENT_INVALID_DMA:
  51                 info.si_signo = SIGBUS;
  52                 info.si_code = BUS_OBJERR;
  53                 break;
  54         case SPE_EVENT_SPE_DATA_STORAGE:
  55                 info.si_signo = SIGSEGV;
  56                 info.si_addr = (void __user *)ea;
  57                 info.si_code = SEGV_ACCERR;
  58                 ctx->ops->restart_dma(ctx);
  59                 break;
  60         case SPE_EVENT_DMA_ALIGNMENT:
  61                 info.si_signo = SIGBUS;
  62                 /* DAR isn't set for an alignment fault :( */
  63                 info.si_code = BUS_ADRALN;
  64                 break;
  65         case SPE_EVENT_SPE_ERROR:
  66                 info.si_signo = SIGILL;
  67                 info.si_addr = (void __user *)(unsigned long)
  68                         ctx->ops->npc_read(ctx) - 4;
  69                 info.si_code = ILL_ILLOPC;
  70                 break;
  71         }
  72
  73         if (info.si_signo)
  74                 force_sig_info(info.si_signo, &info, current);
  75 }
  76
  77 int spufs_handle_class0(struct spu_context *ctx)
  78 {
  79         unsigned long stat = ctx->csa.class_0_pending & CLASS0_INTR_MASK;
  80
  81         if (likely(!stat))
  82                 return 0;
  83
  84         if (stat & CLASS0_DMA_ALIGNMENT_INTR)
  85                 spufs_handle_event(ctx, ctx->csa.class_0_dar,
  86                         SPE_EVENT_DMA_ALIGNMENT);
  87
  88         if (stat & CLASS0_INVALID_DMA_COMMAND_INTR)
  89                 spufs_handle_event(ctx, ctx->csa.class_0_dar,
  90                         SPE_EVENT_INVALID_DMA);
  91
  92         if (stat & CLASS0_SPU_ERROR_INTR)
  93                 spufs_handle_event(ctx, ctx->csa.class_0_dar,
  94                         SPE_EVENT_SPE_ERROR);
  95
  96         ctx->csa.class_0_pending = 0;
  97
  98         return -EIO;
  99 }
 100
 101 /*
 102  * bottom half handler for page faults, we can't do this from
 103  * interrupt context, since we might need to sleep.
 104  * we also need to give up the mutex so we can get scheduled
 105  * out while waiting for the backing store.
 106  *
 107  * TODO: try calling hash_page from the interrupt handler first
 108  *       in order to speed up the easy case.
 109  */
 110 int spufs_handle_class1(struct spu_context *ctx)
 111 {
 112         u64 ea, dsisr, access;
 113         unsigned long flags;
 114         unsigned flt = 0;
 115         int ret;
 116
 117         /*
 118          * dar and dsisr get passed from the registers
 119          * to the spu_context, to this function, but not
 120          * back to the spu if it gets scheduled again.
 121          *
 122          * if we don't handle the fault for a saved context
 123          * in time, we can still expect to get the same fault
 124          * the immediately after the context restore.
 125          */
 126         ea = ctx->csa.class_1_dar;
 127         dsisr = ctx->csa.class_1_dsisr;
 128
 129         if (!(dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED)))
 130                 return 0;
 131
 132         spuctx_switch_state(ctx, SPU_UTIL_IOWAIT);
 133
 134         pr_debug("ctx %p: ea %016llx, dsisr %016llx state %d\n", ctx, ea,
 135                 dsisr, ctx->state);
 136
 137         ctx->stats.hash_flt++;
 138         if (ctx->state == SPU_STATE_RUNNABLE)
 139                 ctx->spu->stats.hash_flt++;
 140
 141         /* we must not hold the lock when entering spu_handle_mm_fault */
 142         spu_release(ctx);
 143
 144         access = (_PAGE_PRESENT | _PAGE_USER);
 145         access |= (dsisr & MFC_DSISR_ACCESS_PUT) ? _PAGE_RW : 0UL;
 146         local_irq_save(flags);
 147         ret = hash_page(ea, access, 0x300);
 148         local_irq_restore(flags);
 149
 150         /* hashing failed, so try the actual fault handler */
 151         if (ret)
 152                 ret = spu_handle_mm_fault(current->mm, ea, dsisr, &flt);
 153
 154         /*
 155          * This is nasty: we need the state_mutex for all the bookkeeping even
 156          * if the syscall was interrupted by a signal. ewww.
 157          */
 158         mutex_lock(&ctx->state_mutex);
 159
 160         /*
 161          * Clear dsisr under ctxt lock after handling the fault, so that
 162          * time slicing will not preempt the context while the page fault
 163          * handler is running. Context switch code removes mappings.
 164          */
 165         ctx->csa.class_1_dar = ctx->csa.class_1_dsisr = 0;
 166
 167         /*
 168          * If we handled the fault successfully and are in runnable
 169          * state, restart the DMA.
 170          * In case of unhandled error report the problem to user space.
 171          */
 172         if (!ret) {
 173                 if (flt & VM_FAULT_MAJOR)
 174                         ctx->stats.maj_flt++;
 175                 else
 176                         ctx->stats.min_flt++;
 177                 if (ctx->state == SPU_STATE_RUNNABLE) {
 178                         if (flt & VM_FAULT_MAJOR)
 179                                 ctx->spu->stats.maj_flt++;
 180                         else
 181                                 ctx->spu->stats.min_flt++;
 182                 }
 183
 184                 if (ctx->spu)
 185                         ctx->ops->restart_dma(ctx);
 186         } else
 187                 spufs_handle_event(ctx, ea, SPE_EVENT_SPE_DATA_STORAGE);
 188
 189         spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 190         return ret;
 191 }