// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Low-level SPU handling
 *
 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
 *
 * Author: Arnd Bergmann <arndb@de.ibm.com>
 */
#include <linux/sched/signal.h>
#include <linux/mm.h>

#include <asm/spu.h>
#include <asm/spu_csa.h>

#include "spufs.h"

/**
 * Handle an SPE event, depending on context SPU_CREATE_EVENTS_ENABLED flag.
 *
 * If the context was created with events, we just set the return event.
 * Otherwise, send an appropriate signal to the process.
 */
static void spufs_handle_event(struct spu_context *ctx,
                                unsigned long ea, int type)
{
        if (ctx->flags & SPU_CREATE_EVENTS_ENABLED) {
                ctx->event_return |= type;
                wake_up_all(&ctx->stop_wq);
                return;
        }

        switch (type) {
        case SPE_EVENT_INVALID_DMA:
                force_sig_fault(SIGBUS, BUS_OBJERR, NULL);
                break;
        case SPE_EVENT_SPE_DATA_STORAGE:
                ctx->ops->restart_dma(ctx);
                force_sig_fault(SIGSEGV, SEGV_ACCERR, (void __user *)ea);
                break;
        case SPE_EVENT_DMA_ALIGNMENT:
                /* DAR isn't set for an alignment fault :( */
                force_sig_fault(SIGBUS, BUS_ADRALN, NULL);
                break;
        case SPE_EVENT_SPE_ERROR:
                force_sig_fault(
                        SIGILL, ILL_ILLOPC,
                        (void __user *)(unsigned long)
                        ctx->ops->npc_read(ctx) - 4);
                break;
        }
}

int spufs_handle_class0(struct spu_context *ctx)
{
        unsigned long stat = ctx->csa.class_0_pending & CLASS0_INTR_MASK;

        if (likely(!stat))
                return 0;

        if (stat & CLASS0_DMA_ALIGNMENT_INTR)
                spufs_handle_event(ctx, ctx->csa.class_0_dar,
                        SPE_EVENT_DMA_ALIGNMENT);

        if (stat & CLASS0_INVALID_DMA_COMMAND_INTR)
                spufs_handle_event(ctx, ctx->csa.class_0_dar,
                        SPE_EVENT_INVALID_DMA);

        if (stat & CLASS0_SPU_ERROR_INTR)
                spufs_handle_event(ctx, ctx->csa.class_0_dar,
                        SPE_EVENT_SPE_ERROR);

        ctx->csa.class_0_pending = 0;

        return -EIO;
}

/*
 * bottom half handler for page faults, we can't do this from
 * interrupt context, since we might need to sleep.
 * we also need to give up the mutex so we can get scheduled
 * out while waiting for the backing store.
 *
 * TODO: try calling hash_page from the interrupt handler first
 *       in order to speed up the easy case.
 */
int spufs_handle_class1(struct spu_context *ctx)
{
        u64 ea, dsisr, access;
        unsigned long flags;
        vm_fault_t flt = 0;
        int ret;

        /*
         * dar and dsisr get passed from the registers
         * to the spu_context, to this function, but not
         * back to the spu if it gets scheduled again.
         *
         * if we don't handle the fault for a saved context
         * in time, we can still expect to get the same fault
         * the immediately after the context restore.
         */
        ea = ctx->csa.class_1_dar;
        dsisr = ctx->csa.class_1_dsisr;

        if (!(dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED)))
                return 0;

        spuctx_switch_state(ctx, SPU_UTIL_IOWAIT);

        pr_debug("ctx %p: ea %016llx, dsisr %016llx state %d\n", ctx, ea,
                dsisr, ctx->state);

        ctx->stats.hash_flt++;
        if (ctx->state == SPU_STATE_RUNNABLE)
                ctx->spu->stats.hash_flt++;

        /* we must not hold the lock when entering copro_handle_mm_fault */
        spu_release(ctx);

        access = (_PAGE_PRESENT | _PAGE_READ);
        access |= (dsisr & MFC_DSISR_ACCESS_PUT) ? _PAGE_WRITE : 0UL;
        local_irq_save(flags);
        ret = hash_page(ea, access, 0x300, dsisr);
        local_irq_restore(flags);

        /* hashing failed, so try the actual fault handler */
        if (ret)
                ret = copro_handle_mm_fault(current->mm, ea, dsisr, &flt);

        /*
         * This is nasty: we need the state_mutex for all the bookkeeping even
         * if the syscall was interrupted by a signal. ewww.
         */
        mutex_lock(&ctx->state_mutex);

        /*
         * Clear dsisr under ctxt lock after handling the fault, so that
         * time slicing will not preempt the context while the page fault
         * handler is running. Context switch code removes mappings.
         */
        ctx->csa.class_1_dar = ctx->csa.class_1_dsisr = 0;

        /*
         * If we handled the fault successfully and are in runnable
         * state, restart the DMA.
         * In case of unhandled error report the problem to user space.
         */
        if (!ret) {
                if (flt & VM_FAULT_MAJOR)
                        ctx->stats.maj_flt++;
                else
                        ctx->stats.min_flt++;
                if (ctx->state == SPU_STATE_RUNNABLE) {
                        if (flt & VM_FAULT_MAJOR)
                                ctx->spu->stats.maj_flt++;
                        else
                                ctx->spu->stats.min_flt++;
                }

                if (ctx->spu)
                        ctx->ops->restart_dma(ctx);
        } else
                spufs_handle_event(ctx, ea, SPE_EVENT_SPE_DATA_STORAGE);

        spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
        return ret;
}