target-microblaze/mmu.c

   1 /*
   2  *  Microblaze MMU emulation for qemu.
   3  *
   4  *  Copyright (c) 2009 Edgar E. Iglesias
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <assert.h>
  22
  23 #include "config.h"
  24 #include "cpu.h"
  25
  26 #define D(x)
  27
  28 static unsigned int tlb_decode_size(unsigned int f)
  29 {
  30     static const unsigned int sizes[] = {
  31         1 * 1024, 4 * 1024, 16 * 1024, 64 * 1024, 256 * 1024,
  32         1 * 1024 * 1024, 4 * 1024 * 1024, 16 * 1024 * 1024
  33     };
  34     assert(f < ARRAY_SIZE(sizes));
  35     return sizes[f];
  36 }
  37
  38 static void mmu_flush_idx(CPUState *env, unsigned int idx)
  39 {
  40     struct microblaze_mmu *mmu = &env->mmu;
  41     unsigned int tlb_size;
  42     uint32_t tlb_tag, end, t;
  43
  44     t = mmu->rams[RAM_TAG][idx];
  45     if (!(t & TLB_VALID))
  46         return;
  47
  48     tlb_tag = t & TLB_EPN_MASK;
  49     tlb_size = tlb_decode_size((t & TLB_PAGESZ_MASK) >> 7);
  50     end = tlb_tag + tlb_size;
  51
  52     while (tlb_tag < end) {
  53         tlb_flush_page(env, tlb_tag);
  54         tlb_tag += TARGET_PAGE_SIZE;
  55     }
  56 }
  57
  58 static void mmu_change_pid(CPUState *env, unsigned int newpid)
  59 {
  60     struct microblaze_mmu *mmu = &env->mmu;
  61     unsigned int i;
  62     uint32_t t;
  63
  64     if (newpid & ~0xff)
  65         qemu_log("Illegal rpid=%x\n", newpid);
  66
  67     for (i = 0; i < ARRAY_SIZE(mmu->rams[RAM_TAG]); i++) {
  68         /* Lookup and decode.  */
  69         t = mmu->rams[RAM_TAG][i];
  70         if (t & TLB_VALID) {
  71             if (mmu->tids[i] && ((mmu->regs[MMU_R_PID] & 0xff) == mmu->tids[i]))
  72                 mmu_flush_idx(env, i);
  73         }
  74     }
  75 }
  76
  77 /* rw - 0 = read, 1 = write, 2 = fetch.  */
  78 unsigned int mmu_translate(struct microblaze_mmu *mmu,
  79                            struct microblaze_mmu_lookup *lu,
  80                            target_ulong vaddr, int rw, int mmu_idx)
  81 {
  82     unsigned int i, hit = 0;
  83     unsigned int tlb_ex = 0, tlb_wr = 0, tlb_zsel;
  84     unsigned int tlb_size;
  85     uint32_t tlb_tag, tlb_rpn, mask, t0;
  86
  87     lu->err = ERR_MISS;
  88     for (i = 0; i < ARRAY_SIZE(mmu->rams[RAM_TAG]); i++) {
  89         uint32_t t, d;
  90
  91         /* Lookup and decode.  */
  92         t = mmu->rams[RAM_TAG][i];
  93         D(qemu_log("TLB %d valid=%d\n", i, t & TLB_VALID));
  94         if (t & TLB_VALID) {
  95             tlb_size = tlb_decode_size((t & TLB_PAGESZ_MASK) >> 7);
  96             if (tlb_size < TARGET_PAGE_SIZE) {
  97                 qemu_log("%d pages not supported\n", tlb_size);
  98                 abort();
  99             }
 100
 101             mask = ~(tlb_size - 1);
 102             tlb_tag = t & TLB_EPN_MASK;
 103             if ((vaddr & mask) != (tlb_tag & mask)) {
 104                 D(qemu_log("TLB %d vaddr=%x != tag=%x\n",
 105                            i, vaddr & mask, tlb_tag & mask));
 106                 continue;
 107             }
 108             if (mmu->tids[i]
 109                 && ((mmu->regs[MMU_R_PID] & 0xff) != mmu->tids[i])) {
 110                 D(qemu_log("TLB %d pid=%x != tid=%x\n",
 111                            i, mmu->regs[MMU_R_PID], mmu->tids[i]));
 112                 continue;
 113             }
 114
 115             /* Bring in the data part.  */
 116             d = mmu->rams[RAM_DATA][i];
 117             tlb_ex = d & TLB_EX;
 118             tlb_wr = d & TLB_WR;
 119
 120             /* Now lets see if there is a zone that overrides the protbits.  */
 121             tlb_zsel = (d >> 4) & 0xf;
 122             t0 = mmu->regs[MMU_R_ZPR] >> (30 - (tlb_zsel * 2));
 123             t0 &= 0x3;
 124
 125             if (tlb_zsel > mmu->c_mmu_zones) {
 126                 qemu_log("tlb zone select out of range! %d\n", tlb_zsel);
 127                 t0 = 1; /* Ignore.  */
 128             }
 129
 130             if (mmu->c_mmu == 1) {
 131                 t0 = 1; /* Zones are disabled.  */
 132             }
 133
 134             switch (t0) {
 135                 case 0:
 136                     if (mmu_idx == MMU_USER_IDX)
 137                         continue;
 138                     break;
 139                 case 2:
 140                     if (mmu_idx != MMU_USER_IDX) {
 141                         tlb_ex = 1;
 142                         tlb_wr = 1;
 143                     }
 144                     break;
 145                 case 3:
 146                     tlb_ex = 1;
 147                     tlb_wr = 1;
 148                     break;
 149                 default: break;
 150             }
 151
 152             lu->err = ERR_PROT;
 153             lu->prot = PAGE_READ;
 154             if (tlb_wr)
 155                 lu->prot |= PAGE_WRITE;
 156             else if (rw == 1)
 157                 goto done;
 158             if (tlb_ex)
 159                 lu->prot |=PAGE_EXEC;
 160             else if (rw == 2) {
 161                 goto done;
 162             }
 163
 164             tlb_rpn = d & TLB_RPN_MASK;
 165
 166             lu->vaddr = tlb_tag;
 167             lu->paddr = tlb_rpn;
 168             lu->size = tlb_size;
 169             lu->err = ERR_HIT;
 170             lu->idx = i;
 171             hit = 1;
 172             goto done;
 173         }
 174     }
 175 done:
 176     D(qemu_log("MMU vaddr=%x rw=%d tlb_wr=%d tlb_ex=%d hit=%d\n",
 177               vaddr, rw, tlb_wr, tlb_ex, hit));
 178     return hit;
 179 }
 180
 181 /* Writes/reads to the MMU's special regs end up here.  */
 182 uint32_t mmu_read(CPUState *env, uint32_t rn)
 183 {
 184     unsigned int i;
 185     uint32_t r;
 186
 187     if (env->mmu.c_mmu < 2 || !env->mmu.c_mmu_tlb_access) {
 188         qemu_log("MMU access on MMU-less system\n");
 189         return 0;
 190     }
 191
 192     switch (rn) {
 193         /* Reads to HI/LO trig reads from the mmu rams.  */
 194         case MMU_R_TLBLO:
 195         case MMU_R_TLBHI:
 196             if (!(env->mmu.c_mmu_tlb_access & 1)) {
 197                 qemu_log("Invalid access to MMU reg %d\n", rn);
 198                 return 0;
 199             }
 200
 201             i = env->mmu.regs[MMU_R_TLBX] & 0xff;
 202             r = env->mmu.rams[rn & 1][i];
 203             if (rn == MMU_R_TLBHI)
 204                 env->mmu.regs[MMU_R_PID] = env->mmu.tids[i];
 205             break;
 206         case MMU_R_PID:
 207         case MMU_R_ZPR:
 208             if (!(env->mmu.c_mmu_tlb_access & 1)) {
 209                 qemu_log("Invalid access to MMU reg %d\n", rn);
 210                 return 0;
 211             }
 212             r = env->mmu.regs[rn];
 213             break;
 214         default:
 215             r = env->mmu.regs[rn];
 216             break;
 217     }
 218     D(qemu_log("%s rn=%d=%x\n", __func__, rn, r));
 219     return r;
 220 }
 221
 222 void mmu_write(CPUState *env, uint32_t rn, uint32_t v)
 223 {
 224     unsigned int i;
 225     D(qemu_log("%s rn=%d=%x old=%x\n", __func__, rn, v, env->mmu.regs[rn]));
 226
 227     if (env->mmu.c_mmu < 2 || !env->mmu.c_mmu_tlb_access) {
 228         qemu_log("MMU access on MMU-less system\n");
 229         return;
 230     }
 231
 232     switch (rn) {
 233         /* Writes to HI/LO trig writes to the mmu rams.  */
 234         case MMU_R_TLBLO:
 235         case MMU_R_TLBHI:
 236             i = env->mmu.regs[MMU_R_TLBX] & 0xff;
 237             if (rn == MMU_R_TLBHI) {
 238                 if (i < 3 && !(v & TLB_VALID) && qemu_loglevel_mask(~0))
 239                     qemu_log("invalidating index %x at pc=%x\n",
 240                              i, env->sregs[SR_PC]);
 241                 env->mmu.tids[i] = env->mmu.regs[MMU_R_PID] & 0xff;
 242                 mmu_flush_idx(env, i);
 243             }
 244             env->mmu.rams[rn & 1][i] = v;
 245
 246             D(qemu_log("%s ram[%d][%d]=%x\n", __func__, rn & 1, i, v));
 247             break;
 248         case MMU_R_ZPR:
 249             if (env->mmu.c_mmu_tlb_access <= 1) {
 250                 qemu_log("Invalid access to MMU reg %d\n", rn);
 251                 return;
 252             }
 253
 254             /* Changes to the zone protection reg flush the QEMU TLB.
 255                Fortunately, these are very uncommon.  */
 256             if (v != env->mmu.regs[rn]) {
 257                 tlb_flush(env, 1);
 258             }
 259             env->mmu.regs[rn] = v;
 260             break;
 261         case MMU_R_PID:
 262             if (env->mmu.c_mmu_tlb_access <= 1) {
 263                 qemu_log("Invalid access to MMU reg %d\n", rn);
 264                 return;
 265             }
 266
 267             if (v != env->mmu.regs[rn]) {
 268                 mmu_change_pid(env, v);
 269                 env->mmu.regs[rn] = v;
 270             }
 271             break;
 272         case MMU_R_TLBSX:
 273         {
 274             struct microblaze_mmu_lookup lu;
 275             int hit;
 276
 277             if (env->mmu.c_mmu_tlb_access <= 1) {
 278                 qemu_log("Invalid access to MMU reg %d\n", rn);
 279                 return;
 280             }
 281
 282             hit = mmu_translate(&env->mmu, &lu,
 283                                 v & TLB_EPN_MASK, 0, cpu_mmu_index(env));
 284             if (hit) {
 285                 env->mmu.regs[MMU_R_TLBX] = lu.idx;
 286             } else
 287                 env->mmu.regs[MMU_R_TLBX] |= 0x80000000;
 288             break;
 289         }
 290         default:
 291             env->mmu.regs[rn] = v;
 292             break;
 293    }
 294 }
 295
 296 void mmu_init(struct microblaze_mmu *mmu)
 297 {
 298     int i;
 299     for (i = 0; i < ARRAY_SIZE(mmu->regs); i++) {
 300         mmu->regs[i] = 0;
 301     }
 302 }