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  * This ought to be kept in sync with the powerpc specific do_page_fault
  33  * function. Currently, there are a few corner cases that we haven't had
  34  * to handle fortunately.
  35  */
  36 static int spu_handle_mm_fault(struct mm_struct *mm, unsigned long ea,
  37                 unsigned long dsisr, unsigned *flt)
  38 {
  39         struct vm_area_struct *vma;
  40         unsigned long is_write;
  41         int ret;
  42
  43 #if 0
  44         if (!IS_VALID_EA(ea)) {
  45                 return -EFAULT;
  46         }
  47 #endif /* XXX */
  48         if (mm == NULL) {
  49                 return -EFAULT;
  50         }
  51         if (mm->pgd == NULL) {
  52                 return -EFAULT;
  53         }
  54
  55         down_read(&mm->mmap_sem);
  56         vma = find_vma(mm, ea);
  57         if (!vma)
  58                 goto bad_area;
  59         if (vma->vm_start <= ea)
  60                 goto good_area;
  61         if (!(vma->vm_flags & VM_GROWSDOWN))
  62                 goto bad_area;
  63         if (expand_stack(vma, ea))
  64                 goto bad_area;
  65 good_area:
  66         is_write = dsisr & MFC_DSISR_ACCESS_PUT;
  67         if (is_write) {
  68                 if (!(vma->vm_flags & VM_WRITE))
  69                         goto bad_area;
  70         } else {
  71                 if (dsisr & MFC_DSISR_ACCESS_DENIED)
  72                         goto bad_area;
  73                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
  74                         goto bad_area;
  75         }
  76         ret = 0;
  77         *flt = handle_mm_fault(mm, vma, ea, is_write);
  78         switch (*flt) {
  79         case VM_FAULT_MINOR:
  80                 current->min_flt++;
  81                 break;
  82         case VM_FAULT_MAJOR:
  83                 current->maj_flt++;
  84                 break;
  85         case VM_FAULT_SIGBUS:
  86                 ret = -EFAULT;
  87                 goto bad_area;
  88         case VM_FAULT_OOM:
  89                 ret = -ENOMEM;
  90                 goto bad_area;
  91         default:
  92                 BUG();
  93         }
  94         up_read(&mm->mmap_sem);
  95         return ret;
  96
  97 bad_area:
  98         up_read(&mm->mmap_sem);
  99         return -EFAULT;
 100 }
 101
 102 static void spufs_handle_dma_error(struct spu_context *ctx,
 103                                 unsigned long ea, int type)
 104 {
 105         if (ctx->flags & SPU_CREATE_EVENTS_ENABLED) {
 106                 ctx->event_return |= type;
 107                 wake_up_all(&ctx->stop_wq);
 108         } else {
 109                 siginfo_t info;
 110                 memset(&info, 0, sizeof(info));
 111
 112                 switch (type) {
 113                 case SPE_EVENT_INVALID_DMA:
 114                         info.si_signo = SIGBUS;
 115                         info.si_code = BUS_OBJERR;
 116                         break;
 117                 case SPE_EVENT_SPE_DATA_STORAGE:
 118                         info.si_signo = SIGBUS;
 119                         info.si_addr = (void __user *)ea;
 120                         info.si_code = BUS_ADRERR;
 121                         break;
 122                 case SPE_EVENT_DMA_ALIGNMENT:
 123                         info.si_signo = SIGBUS;
 124                         /* DAR isn't set for an alignment fault :( */
 125                         info.si_code = BUS_ADRALN;
 126                         break;
 127                 case SPE_EVENT_SPE_ERROR:
 128                         info.si_signo = SIGILL;
 129                         info.si_addr = (void __user *)(unsigned long)
 130                                 ctx->ops->npc_read(ctx) - 4;
 131                         info.si_code = ILL_ILLOPC;
 132                         break;
 133                 }
 134                 if (info.si_signo)
 135                         force_sig_info(info.si_signo, &info, current);
 136         }
 137 }
 138
 139 void spufs_dma_callback(struct spu *spu, int type)
 140 {
 141         spufs_handle_dma_error(spu->ctx, spu->dar, type);
 142 }
 143 EXPORT_SYMBOL_GPL(spufs_dma_callback);
 144
 145 /*
 146  * bottom half handler for page faults, we can't do this from
 147  * interrupt context, since we might need to sleep.
 148  * we also need to give up the mutex so we can get scheduled
 149  * out while waiting for the backing store.
 150  *
 151  * TODO: try calling hash_page from the interrupt handler first
 152  *       in order to speed up the easy case.
 153  */
 154 int spufs_handle_class1(struct spu_context *ctx)
 155 {
 156         u64 ea, dsisr, access;
 157         unsigned long flags;
 158         unsigned flt = 0;
 159         int ret;
 160
 161         /*
 162          * dar and dsisr get passed from the registers
 163          * to the spu_context, to this function, but not
 164          * back to the spu if it gets scheduled again.
 165          *
 166          * if we don't handle the fault for a saved context
 167          * in time, we can still expect to get the same fault
 168          * the immediately after the context restore.
 169          */
 170         if (ctx->state == SPU_STATE_RUNNABLE) {
 171                 ea = ctx->spu->dar;
 172                 dsisr = ctx->spu->dsisr;
 173                 ctx->spu->dar= ctx->spu->dsisr = 0;
 174         } else {
 175                 ea = ctx->csa.priv1.mfc_dar_RW;
 176                 dsisr = ctx->csa.priv1.mfc_dsisr_RW;
 177                 ctx->csa.priv1.mfc_dar_RW = 0;
 178                 ctx->csa.priv1.mfc_dsisr_RW = 0;
 179         }
 180
 181         if (!(dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED)))
 182                 return 0;
 183
 184         spuctx_switch_state(ctx, SPUCTX_UTIL_IOWAIT);
 185
 186         pr_debug("ctx %p: ea %016lx, dsisr %016lx state %d\n", ctx, ea,
 187                 dsisr, ctx->state);
 188
 189         ctx->stats.hash_flt++;
 190
 191         /* we must not hold the lock when entering spu_handle_mm_fault */
 192         spu_release(ctx);
 193
 194         access = (_PAGE_PRESENT | _PAGE_USER);
 195         access |= (dsisr & MFC_DSISR_ACCESS_PUT) ? _PAGE_RW : 0UL;
 196         local_irq_save(flags);
 197         ret = hash_page(ea, access, 0x300);
 198         local_irq_restore(flags);
 199
 200         /* hashing failed, so try the actual fault handler */
 201         if (ret)
 202                 ret = spu_handle_mm_fault(current->mm, ea, dsisr, &flt);
 203
 204         spu_acquire(ctx);
 205         /*
 206          * If we handled the fault successfully and are in runnable
 207          * state, restart the DMA.
 208          * In case of unhandled error report the problem to user space.
 209          */
 210         if (!ret) {
 211                 if (flt == VM_FAULT_MINOR)
 212                         ctx->stats.min_flt++;
 213                 else
 214                         ctx->stats.maj_flt++;
 215
 216                 if (ctx->spu)
 217                         ctx->ops->restart_dma(ctx);
 218         } else
 219                 spufs_handle_dma_error(ctx, ea, SPE_EVENT_SPE_DATA_STORAGE);
 220
 221         spuctx_switch_state(ctx, SPUCTX_UTIL_SYSTEM);
 222         return ret;
 223 }
 224 EXPORT_SYMBOL_GPL(spufs_handle_class1);