LXR linux/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 */
  36static 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
  77int 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 */
 110int 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 copro_handle_mm_fault */
 142        spu_release(ctx);
 143
 144        access = (_PAGE_PRESENT | _PAGE_READ);
 145        access |= (dsisr & MFC_DSISR_ACCESS_PUT) ? _PAGE_WRITE : 0UL;
 146        local_irq_save(flags);
 147        ret = hash_page(ea, access, 0x300, dsisr);
 148        local_irq_restore(flags);
 149
 150        /* hashing failed, so try the actual fault handler */
 151        if (ret)
 152                ret = copro_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}
 192