target/riscv/pmp.c

   1 /*
   2  * QEMU RISC-V PMP (Physical Memory Protection)
   3  *
   4  * Author: Daire McNamara, daire.mcnamara@emdalo.com
   5  *         Ivan Griffin, ivan.griffin@emdalo.com
   6  *
   7  * This provides a RISC-V Physical Memory Protection implementation
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms and conditions of the GNU General Public License,
  11  * version 2 or later, as published by the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope it will be useful, but WITHOUT
  14  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  16  * more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along with
  19  * this program.  If not, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 #include "qemu/osdep.h"
  23 #include "qemu/log.h"
  24 #include "qapi/error.h"
  25 #include "cpu.h"
  26 #include "trace.h"
  27 #include "exec/exec-all.h"
  28
  29 static void pmp_write_cfg(CPURISCVState *env, uint32_t addr_index,
  30     uint8_t val);
  31 static uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t addr_index);
  32 static void pmp_update_rule(CPURISCVState *env, uint32_t pmp_index);
  33
  34 /*
  35  * Accessor method to extract address matching type 'a field' from cfg reg
  36  */
  37 static inline uint8_t pmp_get_a_field(uint8_t cfg)
  38 {
  39     uint8_t a = cfg >> 3;
  40     return a & 0x3;
  41 }
  42
  43 /*
  44  * Check whether a PMP is locked or not.
  45  */
  46 static inline int pmp_is_locked(CPURISCVState *env, uint32_t pmp_index)
  47 {
  48
  49     if (env->pmp_state.pmp[pmp_index].cfg_reg & PMP_LOCK) {
  50         return 1;
  51     }
  52
  53     /* Top PMP has no 'next' to check */
  54     if ((pmp_index + 1u) >= MAX_RISCV_PMPS) {
  55         return 0;
  56     }
  57
  58     return 0;
  59 }
  60
  61 /*
  62  * Count the number of active rules.
  63  */
  64 uint32_t pmp_get_num_rules(CPURISCVState *env)
  65 {
  66      return env->pmp_state.num_rules;
  67 }
  68
  69 /*
  70  * Accessor to get the cfg reg for a specific PMP/HART
  71  */
  72 static inline uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t pmp_index)
  73 {
  74     if (pmp_index < MAX_RISCV_PMPS) {
  75         return env->pmp_state.pmp[pmp_index].cfg_reg;
  76     }
  77
  78     return 0;
  79 }
  80
  81
  82 /*
  83  * Accessor to set the cfg reg for a specific PMP/HART
  84  * Bounds checks and relevant lock bit.
  85  */
  86 static void pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
  87 {
  88     if (pmp_index < MAX_RISCV_PMPS) {
  89         bool locked = true;
  90
  91         if (riscv_cpu_cfg(env)->epmp) {
  92             /* mseccfg.RLB is set */
  93             if (MSECCFG_RLB_ISSET(env)) {
  94                 locked = false;
  95             }
  96
  97             /* mseccfg.MML is not set */
  98             if (!MSECCFG_MML_ISSET(env) && !pmp_is_locked(env, pmp_index)) {
  99                 locked = false;
 100             }
 101
 102             /* mseccfg.MML is set */
 103             if (MSECCFG_MML_ISSET(env)) {
 104                 /* not adding execute bit */
 105                 if ((val & PMP_LOCK) != 0 && (val & PMP_EXEC) != PMP_EXEC) {
 106                     locked = false;
 107                 }
 108                 /* shared region and not adding X bit */
 109                 if ((val & PMP_LOCK) != PMP_LOCK &&
 110                     (val & 0x7) != (PMP_WRITE | PMP_EXEC)) {
 111                     locked = false;
 112                 }
 113             }
 114         } else {
 115             if (!pmp_is_locked(env, pmp_index)) {
 116                 locked = false;
 117             }
 118         }
 119
 120         if (locked) {
 121             qemu_log_mask(LOG_GUEST_ERROR, "ignoring pmpcfg write - locked\n");
 122         } else {
 123             env->pmp_state.pmp[pmp_index].cfg_reg = val;
 124             pmp_update_rule(env, pmp_index);
 125         }
 126     } else {
 127         qemu_log_mask(LOG_GUEST_ERROR,
 128                       "ignoring pmpcfg write - out of bounds\n");
 129     }
 130 }
 131
 132 static void pmp_decode_napot(target_ulong a, target_ulong *sa, target_ulong *ea)
 133 {
 134     /*
 135        aaaa...aaa0   8-byte NAPOT range
 136        aaaa...aa01   16-byte NAPOT range
 137        aaaa...a011   32-byte NAPOT range
 138        ...
 139        aa01...1111   2^XLEN-byte NAPOT range
 140        a011...1111   2^(XLEN+1)-byte NAPOT range
 141        0111...1111   2^(XLEN+2)-byte NAPOT range
 142        1111...1111   Reserved
 143     */
 144     a = (a << 2) | 0x3;
 145     *sa = a & (a + 1);
 146     *ea = a | (a + 1);
 147 }
 148
 149 void pmp_update_rule_addr(CPURISCVState *env, uint32_t pmp_index)
 150 {
 151     uint8_t this_cfg = env->pmp_state.pmp[pmp_index].cfg_reg;
 152     target_ulong this_addr = env->pmp_state.pmp[pmp_index].addr_reg;
 153     target_ulong prev_addr = 0u;
 154     target_ulong sa = 0u;
 155     target_ulong ea = 0u;
 156
 157     if (pmp_index >= 1u) {
 158         prev_addr = env->pmp_state.pmp[pmp_index - 1].addr_reg;
 159     }
 160
 161     switch (pmp_get_a_field(this_cfg)) {
 162     case PMP_AMATCH_OFF:
 163         sa = 0u;
 164         ea = -1;
 165         break;
 166
 167     case PMP_AMATCH_TOR:
 168         sa = prev_addr << 2; /* shift up from [xx:0] to [xx+2:2] */
 169         ea = (this_addr << 2) - 1u;
 170         if (sa > ea) {
 171             sa = ea = 0u;
 172         }
 173         break;
 174
 175     case PMP_AMATCH_NA4:
 176         sa = this_addr << 2; /* shift up from [xx:0] to [xx+2:2] */
 177         ea = (sa + 4u) - 1u;
 178         break;
 179
 180     case PMP_AMATCH_NAPOT:
 181         pmp_decode_napot(this_addr, &sa, &ea);
 182         break;
 183
 184     default:
 185         sa = 0u;
 186         ea = 0u;
 187         break;
 188     }
 189
 190     env->pmp_state.addr[pmp_index].sa = sa;
 191     env->pmp_state.addr[pmp_index].ea = ea;
 192 }
 193
 194 void pmp_update_rule_nums(CPURISCVState *env)
 195 {
 196     int i;
 197
 198     env->pmp_state.num_rules = 0;
 199     for (i = 0; i < MAX_RISCV_PMPS; i++) {
 200         const uint8_t a_field =
 201             pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg);
 202         if (PMP_AMATCH_OFF != a_field) {
 203             env->pmp_state.num_rules++;
 204         }
 205     }
 206 }
 207
 208 /* Convert cfg/addr reg values here into simple 'sa' --> start address and 'ea'
 209  *   end address values.
 210  *   This function is called relatively infrequently whereas the check that
 211  *   an address is within a pmp rule is called often, so optimise that one
 212  */
 213 static void pmp_update_rule(CPURISCVState *env, uint32_t pmp_index)
 214 {
 215     pmp_update_rule_addr(env, pmp_index);
 216     pmp_update_rule_nums(env);
 217 }
 218
 219 static int pmp_is_in_range(CPURISCVState *env, int pmp_index, target_ulong addr)
 220 {
 221     int result = 0;
 222
 223     if ((addr >= env->pmp_state.addr[pmp_index].sa)
 224         && (addr <= env->pmp_state.addr[pmp_index].ea)) {
 225         result = 1;
 226     } else {
 227         result = 0;
 228     }
 229
 230     return result;
 231 }
 232
 233 /*
 234  * Check if the address has required RWX privs when no PMP entry is matched.
 235  */
 236 static bool pmp_hart_has_privs_default(CPURISCVState *env, target_ulong addr,
 237     target_ulong size, pmp_priv_t privs, pmp_priv_t *allowed_privs,
 238     target_ulong mode)
 239 {
 240     bool ret;
 241
 242     if (riscv_cpu_cfg(env)->epmp) {
 243         if (MSECCFG_MMWP_ISSET(env)) {
 244             /*
 245              * The Machine Mode Whitelist Policy (mseccfg.MMWP) is set
 246              * so we default to deny all, even for M-mode.
 247              */
 248             *allowed_privs = 0;
 249             return false;
 250         } else if (MSECCFG_MML_ISSET(env)) {
 251             /*
 252              * The Machine Mode Lockdown (mseccfg.MML) bit is set
 253              * so we can only execute code in M-mode with an applicable
 254              * rule. Other modes are disabled.
 255              */
 256             if (mode == PRV_M && !(privs & PMP_EXEC)) {
 257                 ret = true;
 258                 *allowed_privs = PMP_READ | PMP_WRITE;
 259             } else {
 260                 ret = false;
 261                 *allowed_privs = 0;
 262             }
 263
 264             return ret;
 265         }
 266     }
 267
 268     if (!riscv_cpu_cfg(env)->pmp || (mode == PRV_M)) {
 269         /*
 270          * Privileged spec v1.10 states if HW doesn't implement any PMP entry
 271          * or no PMP entry matches an M-Mode access, the access succeeds.
 272          */
 273         ret = true;
 274         *allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
 275     } else {
 276         /*
 277          * Other modes are not allowed to succeed if they don't * match a rule,
 278          * but there are rules. We've checked for no rule earlier in this
 279          * function.
 280          */
 281         ret = false;
 282         *allowed_privs = 0;
 283     }
 284
 285     return ret;
 286 }
 287
 288
 289 /*
 290  * Public Interface
 291  */
 292
 293 /*
 294  * Check if the address has required RWX privs to complete desired operation
 295  * Return PMP rule index if a pmp rule match
 296  * Return MAX_RISCV_PMPS if default match
 297  * Return negtive value if no match
 298  */
 299 int pmp_hart_has_privs(CPURISCVState *env, target_ulong addr,
 300     target_ulong size, pmp_priv_t privs, pmp_priv_t *allowed_privs,
 301     target_ulong mode)
 302 {
 303     int i = 0;
 304     int ret = -1;
 305     int pmp_size = 0;
 306     target_ulong s = 0;
 307     target_ulong e = 0;
 308
 309     /* Short cut if no rules */
 310     if (0 == pmp_get_num_rules(env)) {
 311         if (pmp_hart_has_privs_default(env, addr, size, privs,
 312                                        allowed_privs, mode)) {
 313             ret = MAX_RISCV_PMPS;
 314         }
 315     }
 316
 317     if (size == 0) {
 318         if (riscv_cpu_cfg(env)->mmu) {
 319             /*
 320              * If size is unknown (0), assume that all bytes
 321              * from addr to the end of the page will be accessed.
 322              */
 323             pmp_size = -(addr | TARGET_PAGE_MASK);
 324         } else {
 325             pmp_size = sizeof(target_ulong);
 326         }
 327     } else {
 328         pmp_size = size;
 329     }
 330
 331     /* 1.10 draft priv spec states there is an implicit order
 332          from low to high */
 333     for (i = 0; i < MAX_RISCV_PMPS; i++) {
 334         s = pmp_is_in_range(env, i, addr);
 335         e = pmp_is_in_range(env, i, addr + pmp_size - 1);
 336
 337         /* partially inside */
 338         if ((s + e) == 1) {
 339             qemu_log_mask(LOG_GUEST_ERROR,
 340                           "pmp violation - access is partially inside\n");
 341             ret = -1;
 342             break;
 343         }
 344
 345         /* fully inside */
 346         const uint8_t a_field =
 347             pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg);
 348
 349         /*
 350          * Convert the PMP permissions to match the truth table in the
 351          * ePMP spec.
 352          */
 353         const uint8_t epmp_operation =
 354             ((env->pmp_state.pmp[i].cfg_reg & PMP_LOCK) >> 4) |
 355             ((env->pmp_state.pmp[i].cfg_reg & PMP_READ) << 2) |
 356             (env->pmp_state.pmp[i].cfg_reg & PMP_WRITE) |
 357             ((env->pmp_state.pmp[i].cfg_reg & PMP_EXEC) >> 2);
 358
 359         if (((s + e) == 2) && (PMP_AMATCH_OFF != a_field)) {
 360             /*
 361              * If the PMP entry is not off and the address is in range,
 362              * do the priv check
 363              */
 364             if (!MSECCFG_MML_ISSET(env)) {
 365                 /*
 366                  * If mseccfg.MML Bit is not set, do pmp priv check
 367                  * This will always apply to regular PMP.
 368                  */
 369                 *allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
 370                 if ((mode != PRV_M) || pmp_is_locked(env, i)) {
 371                     *allowed_privs &= env->pmp_state.pmp[i].cfg_reg;
 372                 }
 373             } else {
 374                 /*
 375                  * If mseccfg.MML Bit set, do the enhanced pmp priv check
 376                  */
 377                 if (mode == PRV_M) {
 378                     switch (epmp_operation) {
 379                     case 0:
 380                     case 1:
 381                     case 4:
 382                     case 5:
 383                     case 6:
 384                     case 7:
 385                     case 8:
 386                         *allowed_privs = 0;
 387                         break;
 388                     case 2:
 389                     case 3:
 390                     case 14:
 391                         *allowed_privs = PMP_READ | PMP_WRITE;
 392                         break;
 393                     case 9:
 394                     case 10:
 395                         *allowed_privs = PMP_EXEC;
 396                         break;
 397                     case 11:
 398                     case 13:
 399                         *allowed_privs = PMP_READ | PMP_EXEC;
 400                         break;
 401                     case 12:
 402                     case 15:
 403                         *allowed_privs = PMP_READ;
 404                         break;
 405                     default:
 406                         g_assert_not_reached();
 407                     }
 408                 } else {
 409                     switch (epmp_operation) {
 410                     case 0:
 411                     case 8:
 412                     case 9:
 413                     case 12:
 414                     case 13:
 415                     case 14:
 416                         *allowed_privs = 0;
 417                         break;
 418                     case 1:
 419                     case 10:
 420                     case 11:
 421                         *allowed_privs = PMP_EXEC;
 422                         break;
 423                     case 2:
 424                     case 4:
 425                     case 15:
 426                         *allowed_privs = PMP_READ;
 427                         break;
 428                     case 3:
 429                     case 6:
 430                         *allowed_privs = PMP_READ | PMP_WRITE;
 431                         break;
 432                     case 5:
 433                         *allowed_privs = PMP_READ | PMP_EXEC;
 434                         break;
 435                     case 7:
 436                         *allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
 437                         break;
 438                     default:
 439                         g_assert_not_reached();
 440                     }
 441                 }
 442             }
 443
 444             /*
 445              * If matching address range was found, the protection bits
 446              * defined with PMP must be used. We shouldn't fallback on
 447              * finding default privileges.
 448              */
 449             ret = i;
 450             break;
 451         }
 452     }
 453
 454     /* No rule matched */
 455     if (ret == -1) {
 456         if (pmp_hart_has_privs_default(env, addr, size, privs,
 457                                        allowed_privs, mode)) {
 458             ret = MAX_RISCV_PMPS;
 459         }
 460     }
 461
 462     return ret;
 463 }
 464
 465 /*
 466  * Handle a write to a pmpcfg CSR
 467  */
 468 void pmpcfg_csr_write(CPURISCVState *env, uint32_t reg_index,
 469     target_ulong val)
 470 {
 471     int i;
 472     uint8_t cfg_val;
 473     int pmpcfg_nums = 2 << riscv_cpu_mxl(env);
 474
 475     trace_pmpcfg_csr_write(env->mhartid, reg_index, val);
 476
 477     for (i = 0; i < pmpcfg_nums; i++) {
 478         cfg_val = (val >> 8 * i)  & 0xff;
 479         pmp_write_cfg(env, (reg_index * 4) + i, cfg_val);
 480     }
 481
 482     /* If PMP permission of any addr has been changed, flush TLB pages. */
 483     tlb_flush(env_cpu(env));
 484 }
 485
 486
 487 /*
 488  * Handle a read from a pmpcfg CSR
 489  */
 490 target_ulong pmpcfg_csr_read(CPURISCVState *env, uint32_t reg_index)
 491 {
 492     int i;
 493     target_ulong cfg_val = 0;
 494     target_ulong val = 0;
 495     int pmpcfg_nums = 2 << riscv_cpu_mxl(env);
 496
 497     for (i = 0; i < pmpcfg_nums; i++) {
 498         val = pmp_read_cfg(env, (reg_index * 4) + i);
 499         cfg_val |= (val << (i * 8));
 500     }
 501     trace_pmpcfg_csr_read(env->mhartid, reg_index, cfg_val);
 502
 503     return cfg_val;
 504 }
 505
 506
 507 /*
 508  * Handle a write to a pmpaddr CSR
 509  */
 510 void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index,
 511     target_ulong val)
 512 {
 513     trace_pmpaddr_csr_write(env->mhartid, addr_index, val);
 514
 515     if (addr_index < MAX_RISCV_PMPS) {
 516         /*
 517          * In TOR mode, need to check the lock bit of the next pmp
 518          * (if there is a next).
 519          */
 520         if (addr_index + 1 < MAX_RISCV_PMPS) {
 521             uint8_t pmp_cfg = env->pmp_state.pmp[addr_index + 1].cfg_reg;
 522
 523             if (pmp_cfg & PMP_LOCK &&
 524                 PMP_AMATCH_TOR == pmp_get_a_field(pmp_cfg)) {
 525                 qemu_log_mask(LOG_GUEST_ERROR,
 526                               "ignoring pmpaddr write - pmpcfg + 1 locked\n");
 527                 return;
 528             }
 529         }
 530
 531         if (!pmp_is_locked(env, addr_index)) {
 532             env->pmp_state.pmp[addr_index].addr_reg = val;
 533             pmp_update_rule(env, addr_index);
 534         } else {
 535             qemu_log_mask(LOG_GUEST_ERROR,
 536                           "ignoring pmpaddr write - locked\n");
 537         }
 538     } else {
 539         qemu_log_mask(LOG_GUEST_ERROR,
 540                       "ignoring pmpaddr write - out of bounds\n");
 541     }
 542 }
 543
 544
 545 /*
 546  * Handle a read from a pmpaddr CSR
 547  */
 548 target_ulong pmpaddr_csr_read(CPURISCVState *env, uint32_t addr_index)
 549 {
 550     target_ulong val = 0;
 551
 552     if (addr_index < MAX_RISCV_PMPS) {
 553         val = env->pmp_state.pmp[addr_index].addr_reg;
 554         trace_pmpaddr_csr_read(env->mhartid, addr_index, val);
 555     } else {
 556         qemu_log_mask(LOG_GUEST_ERROR,
 557                       "ignoring pmpaddr read - out of bounds\n");
 558     }
 559
 560     return val;
 561 }
 562
 563 /*
 564  * Handle a write to a mseccfg CSR
 565  */
 566 void mseccfg_csr_write(CPURISCVState *env, target_ulong val)
 567 {
 568     int i;
 569
 570     trace_mseccfg_csr_write(env->mhartid, val);
 571
 572     /* RLB cannot be enabled if it's already 0 and if any regions are locked */
 573     if (!MSECCFG_RLB_ISSET(env)) {
 574         for (i = 0; i < MAX_RISCV_PMPS; i++) {
 575             if (pmp_is_locked(env, i)) {
 576                 val &= ~MSECCFG_RLB;
 577                 break;
 578             }
 579         }
 580     }
 581
 582     /* Sticky bits */
 583     val |= (env->mseccfg & (MSECCFG_MMWP | MSECCFG_MML));
 584
 585     env->mseccfg = val;
 586 }
 587
 588 /*
 589  * Handle a read from a mseccfg CSR
 590  */
 591 target_ulong mseccfg_csr_read(CPURISCVState *env)
 592 {
 593     trace_mseccfg_csr_read(env->mhartid, env->mseccfg);
 594     return env->mseccfg;
 595 }
 596
 597 /*
 598  * Calculate the TLB size if the start address or the end address of
 599  * PMP entry is presented in the TLB page.
 600  */
 601 target_ulong pmp_get_tlb_size(CPURISCVState *env, int pmp_index,
 602                               target_ulong tlb_sa, target_ulong tlb_ea)
 603 {
 604     target_ulong pmp_sa = env->pmp_state.addr[pmp_index].sa;
 605     target_ulong pmp_ea = env->pmp_state.addr[pmp_index].ea;
 606
 607     if (pmp_sa <= tlb_sa && pmp_ea >= tlb_ea) {
 608         return TARGET_PAGE_SIZE;
 609     } else {
 610         /*
 611         * At this point we have a tlb_size that is the smallest possible size
 612         * That fits within a TARGET_PAGE_SIZE and the PMP region.
 613         *
 614         * If the size is less then TARGET_PAGE_SIZE we drop the size to 1.
 615         * This means the result isn't cached in the TLB and is only used for
 616         * a single translation.
 617         */
 618         return 1;
 619     }
 620 }
 621
 622 /*
 623  * Convert PMP privilege to TLB page privilege.
 624  */
 625 int pmp_priv_to_page_prot(pmp_priv_t pmp_priv)
 626 {
 627     int prot = 0;
 628
 629     if (pmp_priv & PMP_READ) {
 630         prot |= PAGE_READ;
 631     }
 632     if (pmp_priv & PMP_WRITE) {
 633         prot |= PAGE_WRITE;
 634     }
 635     if (pmp_priv & PMP_EXEC) {
 636         prot |= PAGE_EXEC;
 637     }
 638
 639     return prot;
 640 }