Archipelago » qemu

/*

 *  CRIS mmu emulation.

 *

 *  Copyright (c) 2007 AXIS Communications AB

 *  Written by 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/>.

 */

#ifndef CONFIG_USER_ONLY

#include "cpu.h"

#include "mmu.h"

#ifdef DEBUG

#define D(x) x

#define D_LOG(...) qemu_log(__VA_ARGS__)

#else

#define D(x) do { } while (0)

#define D_LOG(...) do { } while (0)

#endif

void cris_mmu_init(CPUCRISState *env)

{

        env->mmu_rand_lfsr = 0xcccc;

}

#define SR_POLYNOM 0x8805

static inline unsigned int compute_polynom(unsigned int sr)

{

        unsigned int i;

        unsigned int f;

        f = 0;

        for (i = 0; i < 16; i++)

                f += ((SR_POLYNOM >> i) & 1) & ((sr >> i) & 1);

        return f;

}

static void cris_mmu_update_rand_lfsr(CPUCRISState *env)

{

        unsigned int f;

        /* Update lfsr at every fault.  */

        f = compute_polynom(env->mmu_rand_lfsr);

        env->mmu_rand_lfsr >>= 1;

        env->mmu_rand_lfsr |= (f << 15);

        env->mmu_rand_lfsr &= 0xffff;

}

static inline int cris_mmu_enabled(uint32_t rw_gc_cfg)

{

        return (rw_gc_cfg & 12) != 0;

}

static inline int cris_mmu_segmented_addr(int seg, uint32_t rw_mm_cfg)

{

        return (1 << seg) & rw_mm_cfg;

}

static uint32_t cris_mmu_translate_seg(CPUCRISState *env, int seg)

{

        uint32_t base;

        int i;

        if (seg < 8)

                base = env->sregs[SFR_RW_MM_KBASE_LO];

        else

                base = env->sregs[SFR_RW_MM_KBASE_HI];

        i = seg & 7;

        base >>= i * 4;

        base &= 15;

        base <<= 28;

        return base;

}

/* Used by the tlb decoder.  */

#define EXTRACT_FIELD(src, start, end) \

            (((src) >> start) & ((1 << (end - start + 1)) - 1))

static inline void set_field(uint32_t *dst, unsigned int val, 

                             unsigned int offset, unsigned int width)

{

        uint32_t mask;

        mask = (1 << width) - 1;

        mask <<= offset;

        val <<= offset;

        val &= mask;

        *dst &= ~(mask);

        *dst |= val;

}

#ifdef DEBUG

static void dump_tlb(CPUCRISState *env, int mmu)

{

        int set;

        int idx;

        uint32_t hi, lo, tlb_vpn, tlb_pfn;

        for (set = 0; set < 4; set++) {

                for (idx = 0; idx < 16; idx++) {

                        lo = env->tlbsets[mmu][set][idx].lo;

                        hi = env->tlbsets[mmu][set][idx].hi;

                        tlb_vpn = EXTRACT_FIELD(hi, 13, 31);

                        tlb_pfn = EXTRACT_FIELD(lo, 13, 31);

                        printf ("TLB: [%d][%d] hi=%x lo=%x v=%x p=%x\n", 

                                        set, idx, hi, lo, tlb_vpn, tlb_pfn);

                }

        }

}

#endif

/* rw 0 = read, 1 = write, 2 = exec.  */

static int cris_mmu_translate_page(struct cris_mmu_result *res,

                                   CPUCRISState *env, uint32_t vaddr,

                                   int rw, int usermode, int debug)

{

        unsigned int vpage;

        unsigned int idx;

        uint32_t pid, lo, hi;

        uint32_t tlb_vpn, tlb_pfn = 0;

        int tlb_pid, tlb_g, tlb_v, tlb_k, tlb_w, tlb_x;

        int cfg_v, cfg_k, cfg_w, cfg_x;        

        int set, match = 0;

        uint32_t r_cause;

        uint32_t r_cfg;

        int rwcause;

        int mmu = 1; /* Data mmu is default.  */

        int vect_base;

        r_cause = env->sregs[SFR_R_MM_CAUSE];

        r_cfg = env->sregs[SFR_RW_MM_CFG];

        pid = env->pregs[PR_PID] & 0xff;

        switch (rw) {

                case 2: rwcause = CRIS_MMU_ERR_EXEC; mmu = 0; break;

                case 1: rwcause = CRIS_MMU_ERR_WRITE; break;

                default:

                case 0: rwcause = CRIS_MMU_ERR_READ; break;

        }

        /* I exception vectors 4 - 7, D 8 - 11.  */

        vect_base = (mmu + 1) * 4;

        vpage = vaddr >> 13;

        /* We know the index which to check on each set.

           Scan both I and D.  */

#if 0

        for (set = 0; set < 4; set++) {

                for (idx = 0; idx < 16; idx++) {

                        lo = env->tlbsets[mmu][set][idx].lo;

                        hi = env->tlbsets[mmu][set][idx].hi;

                        tlb_vpn = EXTRACT_FIELD(hi, 13, 31);

                        tlb_pfn = EXTRACT_FIELD(lo, 13, 31);

                        printf ("TLB: [%d][%d] hi=%x lo=%x v=%x p=%x\n", 

                                        set, idx, hi, lo, tlb_vpn, tlb_pfn);

                }

        }

#endif

        idx = vpage & 15;

        for (set = 0; set < 4; set++)

        {

                lo = env->tlbsets[mmu][set][idx].lo;

                hi = env->tlbsets[mmu][set][idx].hi;

                tlb_vpn = hi >> 13;

                tlb_pid = EXTRACT_FIELD(hi, 0, 7);

                tlb_g  = EXTRACT_FIELD(lo, 4, 4);

                D_LOG("TLB[%d][%d][%d] v=%x vpage=%x lo=%x hi=%x\n", 

                         mmu, set, idx, tlb_vpn, vpage, lo, hi);

                if ((tlb_g || (tlb_pid == pid))

                    && tlb_vpn == vpage) {

                        match = 1;

                        break;

                }

        }

        res->bf_vec = vect_base;

        if (match) {

                cfg_w  = EXTRACT_FIELD(r_cfg, 19, 19);

                cfg_k  = EXTRACT_FIELD(r_cfg, 18, 18);

                cfg_x  = EXTRACT_FIELD(r_cfg, 17, 17);

                cfg_v  = EXTRACT_FIELD(r_cfg, 16, 16);

                tlb_pfn = EXTRACT_FIELD(lo, 13, 31);

                tlb_v = EXTRACT_FIELD(lo, 3, 3);

                tlb_k = EXTRACT_FIELD(lo, 2, 2);

                tlb_w = EXTRACT_FIELD(lo, 1, 1);

                tlb_x = EXTRACT_FIELD(lo, 0, 0);

                /*

                set_exception_vector(0x04, i_mmu_refill);

                set_exception_vector(0x05, i_mmu_invalid);

                set_exception_vector(0x06, i_mmu_access);

                set_exception_vector(0x07, i_mmu_execute);

                set_exception_vector(0x08, d_mmu_refill);

                set_exception_vector(0x09, d_mmu_invalid);

                set_exception_vector(0x0a, d_mmu_access);

                set_exception_vector(0x0b, d_mmu_write);

                */

                if (cfg_k && tlb_k && usermode) {

                        D(printf ("tlb: kernel protected %x lo=%x pc=%x\n", 

                                  vaddr, lo, env->pc));

                        match = 0;

                        res->bf_vec = vect_base + 2;

                } else if (rw == 1 && cfg_w && !tlb_w) {

                        D(printf ("tlb: write protected %x lo=%x pc=%x\n", 

                                  vaddr, lo, env->pc));

                        match = 0;

                        /* write accesses never go through the I mmu.  */

                        res->bf_vec = vect_base + 3;

                } else if (rw == 2 && cfg_x && !tlb_x) {

                        D(printf ("tlb: exec protected %x lo=%x pc=%x\n", 

                                 vaddr, lo, env->pc));

                        match = 0;

                        res->bf_vec = vect_base + 3;

                } else if (cfg_v && !tlb_v) {

                        D(printf ("tlb: invalid %x\n", vaddr));

                        match = 0;

                        res->bf_vec = vect_base + 1;

                }

                res->prot = 0;

                if (match) {

                        res->prot |= PAGE_READ;

                        if (tlb_w)

                                res->prot |= PAGE_WRITE;

                        if (mmu == 0 && (cfg_x || tlb_x))

                                res->prot |= PAGE_EXEC;

                }

                else

                        D(dump_tlb(env, mmu));

        } else {

                /* If refill, provide a randomized set.  */

                set = env->mmu_rand_lfsr & 3;

        }

        if (!match && !debug) {

                cris_mmu_update_rand_lfsr(env);

                /* Compute index.  */

                idx = vpage & 15;

                /* Update RW_MM_TLB_SEL.  */

                env->sregs[SFR_RW_MM_TLB_SEL] = 0;

                set_field(&env->sregs[SFR_RW_MM_TLB_SEL], idx, 0, 4);

                set_field(&env->sregs[SFR_RW_MM_TLB_SEL], set, 4, 2);

                /* Update RW_MM_CAUSE.  */

                set_field(&r_cause, rwcause, 8, 2);

                set_field(&r_cause, vpage, 13, 19);

                set_field(&r_cause, pid, 0, 8);

                env->sregs[SFR_R_MM_CAUSE] = r_cause;

                D(printf("refill vaddr=%x pc=%x\n", vaddr, env->pc));

        }

        D(printf ("%s rw=%d mtch=%d pc=%x va=%x vpn=%x tlbvpn=%x pfn=%x pid=%x"

                  " %x cause=%x sel=%x sp=%x %x %x\n",

                  __func__, rw, match, env->pc,

                  vaddr, vpage,

                  tlb_vpn, tlb_pfn, tlb_pid, 

                  pid,

                  r_cause,

                  env->sregs[SFR_RW_MM_TLB_SEL],

                  env->regs[R_SP], env->pregs[PR_USP], env->ksp));

        res->phy = tlb_pfn << TARGET_PAGE_BITS;

        return !match;

}

void cris_mmu_flush_pid(CPUCRISState *env, uint32_t pid)

{

        target_ulong vaddr;

        unsigned int idx;

        uint32_t lo, hi;

        uint32_t tlb_vpn;

        int tlb_pid, tlb_g, tlb_v;

        unsigned int set;

        unsigned int mmu;

        pid &= 0xff;

        for (mmu = 0; mmu < 2; mmu++) {

                for (set = 0; set < 4; set++)

                {

                        for (idx = 0; idx < 16; idx++) {

                                lo = env->tlbsets[mmu][set][idx].lo;

                                hi = env->tlbsets[mmu][set][idx].hi;

                                tlb_vpn = EXTRACT_FIELD(hi, 13, 31);

                                tlb_pid = EXTRACT_FIELD(hi, 0, 7);

                                tlb_g  = EXTRACT_FIELD(lo, 4, 4);

                                tlb_v = EXTRACT_FIELD(lo, 3, 3);

                                if (tlb_v && !tlb_g && (tlb_pid == pid)) {

                                        vaddr = tlb_vpn << TARGET_PAGE_BITS;

                                        D_LOG("flush pid=%x vaddr=%x\n", 

                                                  pid, vaddr);

                                        tlb_flush_page(env, vaddr);

                                }

                        }

                }

        }

}

int cris_mmu_translate(struct cris_mmu_result *res,

                       CPUCRISState *env, uint32_t vaddr,

                       int rw, int mmu_idx, int debug)

{

        int seg;

        int miss = 0;

        int is_user = mmu_idx == MMU_USER_IDX;

        uint32_t old_srs;

        old_srs= env->pregs[PR_SRS];

        /* rw == 2 means exec, map the access to the insn mmu.  */

        env->pregs[PR_SRS] = rw == 2 ? 1 : 2;

        if (!cris_mmu_enabled(env->sregs[SFR_RW_GC_CFG])) {

                res->phy = vaddr;

                res->prot = PAGE_BITS;

                goto done;

        }

        seg = vaddr >> 28;

        if (!is_user && cris_mmu_segmented_addr(seg, env->sregs[SFR_RW_MM_CFG]))

        {

                uint32_t base;

                miss = 0;

                base = cris_mmu_translate_seg(env, seg);

                res->phy = base | (0x0fffffff & vaddr);

                res->prot = PAGE_BITS;

        } else {

                miss = cris_mmu_translate_page(res, env, vaddr, rw,

                                               is_user, debug);

        }

  done:

        env->pregs[PR_SRS] = old_srs;

        return miss;

}

#endif