Archipelago » qemu

/*

 *  Microblaze MMU emulation for qemu.

 *

 *  Copyright (c) 2009 Edgar E. Iglesias

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, see <http://www.gnu.org/licenses/>.

 */

#include <stdio.h>

#include <stdlib.h>

#include <assert.h>

#include "config.h"

#include "cpu.h"

#define D(x)

static unsigned int tlb_decode_size(unsigned int f)

{

    static const unsigned int sizes[] = {

        1 * 1024, 4 * 1024, 16 * 1024, 64 * 1024, 256 * 1024,

        1 * 1024 * 1024, 4 * 1024 * 1024, 16 * 1024 * 1024

    };

    assert(f < ARRAY_SIZE(sizes));

    return sizes[f];

}

static void mmu_flush_idx(CPUState *env, unsigned int idx)

{

    struct microblaze_mmu *mmu = &env->mmu;

    unsigned int tlb_size;

    uint32_t tlb_tag, end, t;

    t = mmu->rams[RAM_TAG][idx];

    if (!(t & TLB_VALID))

        return;

    tlb_tag = t & TLB_EPN_MASK;

    tlb_size = tlb_decode_size((t & TLB_PAGESZ_MASK) >> 7);

    end = tlb_tag + tlb_size;

    while (tlb_tag < end) {

        tlb_flush_page(env, tlb_tag);

        tlb_tag += TARGET_PAGE_SIZE;

    }

}

static void mmu_change_pid(CPUState *env, unsigned int newpid) 

{

    struct microblaze_mmu *mmu = &env->mmu;

    unsigned int i;

    uint32_t t;

    if (newpid & ~0xff)

        qemu_log("Illegal rpid=%x\n", newpid);

    for (i = 0; i < ARRAY_SIZE(mmu->rams[RAM_TAG]); i++) {

        /* Lookup and decode.  */

        t = mmu->rams[RAM_TAG][i];

        if (t & TLB_VALID) {

            if (mmu->tids[i] && ((mmu->regs[MMU_R_PID] & 0xff) == mmu->tids[i]))

                mmu_flush_idx(env, i);

        }

    }

}

/* rw - 0 = read, 1 = write, 2 = fetch.  */

unsigned int mmu_translate(struct microblaze_mmu *mmu,

                           struct microblaze_mmu_lookup *lu,

                           target_ulong vaddr, int rw, int mmu_idx)

{

    unsigned int i, hit = 0;

    unsigned int tlb_ex = 0, tlb_wr = 0, tlb_zsel;

    unsigned int tlb_size;

    uint32_t tlb_tag, tlb_rpn, mask, t0;

    lu->err = ERR_MISS;

    for (i = 0; i < ARRAY_SIZE(mmu->rams[RAM_TAG]); i++) {

        uint32_t t, d;

        /* Lookup and decode.  */

        t = mmu->rams[RAM_TAG][i];

        D(qemu_log("TLB %d valid=%d\n", i, t & TLB_VALID));

        if (t & TLB_VALID) {

            tlb_size = tlb_decode_size((t & TLB_PAGESZ_MASK) >> 7);

            if (tlb_size < TARGET_PAGE_SIZE) {

                qemu_log("%d pages not supported\n", tlb_size);

                abort();

            }

            mask = ~(tlb_size - 1);

            tlb_tag = t & TLB_EPN_MASK;

            if ((vaddr & mask) != (tlb_tag & mask)) {

                D(qemu_log("TLB %d vaddr=%x != tag=%x\n",

                           i, vaddr & mask, tlb_tag & mask));

                continue;

            }

            if (mmu->tids[i]

                && ((mmu->regs[MMU_R_PID] & 0xff) != mmu->tids[i])) {

                D(qemu_log("TLB %d pid=%x != tid=%x\n",

                           i, mmu->regs[MMU_R_PID], mmu->tids[i]));

                continue;

            }

            /* Bring in the data part.  */

            d = mmu->rams[RAM_DATA][i];

            tlb_ex = d & TLB_EX;

            tlb_wr = d & TLB_WR;

            /* Now lets see if there is a zone that overrides the protbits.  */

            tlb_zsel = (d >> 4) & 0xf;

            t0 = mmu->regs[MMU_R_ZPR] >> (30 - (tlb_zsel * 2));

            t0 &= 0x3;

            if (tlb_zsel > mmu->c_mmu_zones) {

                qemu_log("tlb zone select out of range! %d\n", tlb_zsel);

                t0 = 1; /* Ignore.  */

            }

            if (mmu->c_mmu == 1) {

                t0 = 1; /* Zones are disabled.  */

            }

            switch (t0) {

                case 0:

                    if (mmu_idx == MMU_USER_IDX)

                        continue;

                    break;

                case 2:

                    if (mmu_idx != MMU_USER_IDX) {

                        tlb_ex = 1;

                        tlb_wr = 1;

                    }

                    break;

                case 3:

                    tlb_ex = 1;

                    tlb_wr = 1;

                    break;

                default: break;

            }

            lu->err = ERR_PROT;

            lu->prot = PAGE_READ;

            if (tlb_wr)

                lu->prot |= PAGE_WRITE;

            else if (rw == 1)

                goto done;

            if (tlb_ex)

                lu->prot |=PAGE_EXEC;

            else if (rw == 2) {

                goto done;

            }

            tlb_rpn = d & TLB_RPN_MASK;

            lu->vaddr = tlb_tag;

            lu->paddr = tlb_rpn;

            lu->size = tlb_size;

            lu->err = ERR_HIT;

            lu->idx = i;

            hit = 1;

            goto done;

        }

    }

done:

    D(qemu_log("MMU vaddr=%x rw=%d tlb_wr=%d tlb_ex=%d hit=%d\n",

              vaddr, rw, tlb_wr, tlb_ex, hit));

    return hit;

}

/* Writes/reads to the MMU's special regs end up here.  */

uint32_t mmu_read(CPUState *env, uint32_t rn)

{

    unsigned int i;

    uint32_t r;

    if (env->mmu.c_mmu < 2 || !env->mmu.c_mmu_tlb_access) {

        qemu_log("MMU access on MMU-less system\n");

        return 0;

    }

    switch (rn) {

        /* Reads to HI/LO trig reads from the mmu rams.  */

        case MMU_R_TLBLO:

        case MMU_R_TLBHI:

            if (!(env->mmu.c_mmu_tlb_access & 1)) {

                qemu_log("Invalid access to MMU reg %d\n", rn);

                return 0;

            }

            i = env->mmu.regs[MMU_R_TLBX] & 0xff;

            r = env->mmu.rams[rn & 1][i];

            if (rn == MMU_R_TLBHI)

                env->mmu.regs[MMU_R_PID] = env->mmu.tids[i];

            break;

        case MMU_R_PID:

        case MMU_R_ZPR:

            if (!(env->mmu.c_mmu_tlb_access & 1)) {

                qemu_log("Invalid access to MMU reg %d\n", rn);

                return 0;

            }

            r = env->mmu.regs[rn];

            break;

        default:

            r = env->mmu.regs[rn];

            break;

    }

    D(qemu_log("%s rn=%d=%x\n", __func__, rn, r));

    return r;

}

void mmu_write(CPUState *env, uint32_t rn, uint32_t v)

{

    unsigned int i;

    D(qemu_log("%s rn=%d=%x old=%x\n", __func__, rn, v, env->mmu.regs[rn]));

    if (env->mmu.c_mmu < 2 || !env->mmu.c_mmu_tlb_access) {

        qemu_log("MMU access on MMU-less system\n");

        return;

    }

    switch (rn) {

        /* Writes to HI/LO trig writes to the mmu rams.  */

        case MMU_R_TLBLO:

        case MMU_R_TLBHI:

            i = env->mmu.regs[MMU_R_TLBX] & 0xff;

            if (rn == MMU_R_TLBHI) {

                if (i < 3 && !(v & TLB_VALID) && qemu_loglevel_mask(~0))

                    qemu_log("invalidating index %x at pc=%x\n",

                             i, env->sregs[SR_PC]);

                env->mmu.tids[i] = env->mmu.regs[MMU_R_PID] & 0xff;

                mmu_flush_idx(env, i);

            }

            env->mmu.rams[rn & 1][i] = v;

            D(qemu_log("%s ram[%d][%d]=%x\n", __func__, rn & 1, i, v));

            break;

        case MMU_R_ZPR:

            if (env->mmu.c_mmu_tlb_access <= 1) {

                qemu_log("Invalid access to MMU reg %d\n", rn);

                return;

            }

            /* Changes to the zone protection reg flush the QEMU TLB.

               Fortunately, these are very uncommon.  */

            if (v != env->mmu.regs[rn]) {

                tlb_flush(env, 1);

            }

            env->mmu.regs[rn] = v;

            break;

        case MMU_R_PID:

            if (env->mmu.c_mmu_tlb_access <= 1) {

                qemu_log("Invalid access to MMU reg %d\n", rn);

                return;

            }

            if (v != env->mmu.regs[rn]) {

                mmu_change_pid(env, v);

                env->mmu.regs[rn] = v;

            }

            break;

        case MMU_R_TLBSX:

        {

            struct microblaze_mmu_lookup lu;

            int hit;

            if (env->mmu.c_mmu_tlb_access <= 1) {

                qemu_log("Invalid access to MMU reg %d\n", rn);

                return;

            }

            hit = mmu_translate(&env->mmu, &lu,

                                v & TLB_EPN_MASK, 0, cpu_mmu_index(env));

            if (hit) {

                env->mmu.regs[MMU_R_TLBX] = lu.idx;

            } else

                env->mmu.regs[MMU_R_TLBX] |= 0x80000000;

            break;

        }

        default:

            env->mmu.regs[rn] = v;

            break;

   }

}

void mmu_init(struct microblaze_mmu *mmu)

{

    int i;

    for (i = 0; i < ARRAY_SIZE(mmu->regs); i++) {

        mmu->regs[i] = 0;

    }

}