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

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Low-level SPU handling
   4 *
   5 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
   6 *
   7 * Author: Arnd Bergmann <arndb@de.ibm.com>
   8 */
   9#include <linux/sched/signal.h>
  10#include <linux/mm.h>
  11
  12#include <asm/spu.h>
  13#include <asm/spu_csa.h>
  14
  15#include "spufs.h"
  16
  17/**
  18 * Handle an SPE event, depending on context SPU_CREATE_EVENTS_ENABLED flag.
  19 *
  20 * If the context was created with events, we just set the return event.
  21 * Otherwise, send an appropriate signal to the process.
  22 */
  23static void spufs_handle_event(struct spu_context *ctx,
  24                                unsigned long ea, int type)
  25{
  26        if (ctx->flags & SPU_CREATE_EVENTS_ENABLED) {
  27                ctx->event_return |= type;
  28                wake_up_all(&ctx->stop_wq);
  29                return;
  30        }
  31
  32        switch (type) {
  33        case SPE_EVENT_INVALID_DMA:
  34                force_sig_fault(SIGBUS, BUS_OBJERR, NULL, current);
  35                break;
  36        case SPE_EVENT_SPE_DATA_STORAGE:
  37                ctx->ops->restart_dma(ctx);
  38                force_sig_fault(SIGSEGV, SEGV_ACCERR, (void __user *)ea,
  39                                current);
  40                break;
  41        case SPE_EVENT_DMA_ALIGNMENT:
  42                /* DAR isn't set for an alignment fault :( */
  43                force_sig_fault(SIGBUS, BUS_ADRALN, NULL, current);
  44                break;
  45        case SPE_EVENT_SPE_ERROR:
  46                force_sig_fault(
  47                        SIGILL, ILL_ILLOPC,
  48                        (void __user *)(unsigned long)
  49                        ctx->ops->npc_read(ctx) - 4, current);
  50                break;
  51        }
  52}
  53
  54int spufs_handle_class0(struct spu_context *ctx)
  55{
  56        unsigned long stat = ctx->csa.class_0_pending & CLASS0_INTR_MASK;
  57
  58        if (likely(!stat))
  59                return 0;
  60
  61        if (stat & CLASS0_DMA_ALIGNMENT_INTR)
  62                spufs_handle_event(ctx, ctx->csa.class_0_dar,
  63                        SPE_EVENT_DMA_ALIGNMENT);
  64
  65        if (stat & CLASS0_INVALID_DMA_COMMAND_INTR)
  66                spufs_handle_event(ctx, ctx->csa.class_0_dar,
  67                        SPE_EVENT_INVALID_DMA);
  68
  69        if (stat & CLASS0_SPU_ERROR_INTR)
  70                spufs_handle_event(ctx, ctx->csa.class_0_dar,
  71                        SPE_EVENT_SPE_ERROR);
  72
  73        ctx->csa.class_0_pending = 0;
  74
  75        return -EIO;
  76}
  77
  78/*
  79 * bottom half handler for page faults, we can't do this from
  80 * interrupt context, since we might need to sleep.
  81 * we also need to give up the mutex so we can get scheduled
  82 * out while waiting for the backing store.
  83 *
  84 * TODO: try calling hash_page from the interrupt handler first
  85 *       in order to speed up the easy case.
  86 */
  87int spufs_handle_class1(struct spu_context *ctx)
  88{
  89        u64 ea, dsisr, access;
  90        unsigned long flags;
  91        vm_fault_t flt = 0;
  92        int ret;
  93
  94        /*
  95         * dar and dsisr get passed from the registers
  96         * to the spu_context, to this function, but not
  97         * back to the spu if it gets scheduled again.
  98         *
  99         * if we don't handle the fault for a saved context
 100         * in time, we can still expect to get the same fault
 101         * the immediately after the context restore.
 102         */
 103        ea = ctx->csa.class_1_dar;
 104        dsisr = ctx->csa.class_1_dsisr;
 105
 106        if (!(dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED)))
 107                return 0;
 108
 109        spuctx_switch_state(ctx, SPU_UTIL_IOWAIT);
 110
 111        pr_debug("ctx %p: ea %016llx, dsisr %016llx state %d\n", ctx, ea,
 112                dsisr, ctx->state);
 113
 114        ctx->stats.hash_flt++;
 115        if (ctx->state == SPU_STATE_RUNNABLE)
 116                ctx->spu->stats.hash_flt++;
 117
 118        /* we must not hold the lock when entering copro_handle_mm_fault */
 119        spu_release(ctx);
 120
 121        access = (_PAGE_PRESENT | _PAGE_READ);
 122        access |= (dsisr & MFC_DSISR_ACCESS_PUT) ? _PAGE_WRITE : 0UL;
 123        local_irq_save(flags);
 124        ret = hash_page(ea, access, 0x300, dsisr);
 125        local_irq_restore(flags);
 126
 127        /* hashing failed, so try the actual fault handler */
 128        if (ret)
 129                ret = copro_handle_mm_fault(current->mm, ea, dsisr, &flt);
 130
 131        /*
 132         * This is nasty: we need the state_mutex for all the bookkeeping even
 133         * if the syscall was interrupted by a signal. ewww.
 134         */
 135        mutex_lock(&ctx->state_mutex);
 136
 137        /*
 138         * Clear dsisr under ctxt lock after handling the fault, so that
 139         * time slicing will not preempt the context while the page fault
 140         * handler is running. Context switch code removes mappings.
 141         */
 142        ctx->csa.class_1_dar = ctx->csa.class_1_dsisr = 0;
 143
 144        /*
 145         * If we handled the fault successfully and are in runnable
 146         * state, restart the DMA.
 147         * In case of unhandled error report the problem to user space.
 148         */
 149        if (!ret) {
 150                if (flt & VM_FAULT_MAJOR)
 151                        ctx->stats.maj_flt++;
 152                else
 153                        ctx->stats.min_flt++;
 154                if (ctx->state == SPU_STATE_RUNNABLE) {
 155                        if (flt & VM_FAULT_MAJOR)
 156                                ctx->spu->stats.maj_flt++;
 157                        else
 158                                ctx->spu->stats.min_flt++;
 159                }
 160
 161                if (ctx->spu)
 162                        ctx->ops->restart_dma(ctx);
 163        } else
 164                spufs_handle_event(ctx, ea, SPE_EVENT_SPE_DATA_STORAGE);
 165
 166        spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 167        return ret;
 168}
 169