disas.c

   1 /* General "disassemble this chunk" code.  Used for debugging. */
   2 #include "qemu/osdep.h"
   3 #include "qemu-common.h"
   4 #include "disas/bfd.h"
   5 #include "elf.h"
   6
   7 #include "cpu.h"
   8 #include "disas/disas.h"
   9 #include "disas/capstone.h"
  10
  11 typedef struct CPUDebug {
  12     struct disassemble_info info;
  13     CPUState *cpu;
  14 } CPUDebug;
  15
  16 /* Filled in by elfload.c.  Simplistic, but will do for now. */
  17 struct syminfo *syminfos = NULL;
  18
  19 /* Get LENGTH bytes from info's buffer, at target address memaddr.
  20    Transfer them to myaddr.  */
  21 int
  22 buffer_read_memory(bfd_vma memaddr, bfd_byte *myaddr, int length,
  23                    struct disassemble_info *info)
  24 {
  25     if (memaddr < info->buffer_vma
  26         || memaddr + length > info->buffer_vma + info->buffer_length)
  27         /* Out of bounds.  Use EIO because GDB uses it.  */
  28         return EIO;
  29     memcpy (myaddr, info->buffer + (memaddr - info->buffer_vma), length);
  30     return 0;
  31 }
  32
  33 /* Get LENGTH bytes from info's buffer, at target address memaddr.
  34    Transfer them to myaddr.  */
  35 static int
  36 target_read_memory (bfd_vma memaddr,
  37                     bfd_byte *myaddr,
  38                     int length,
  39                     struct disassemble_info *info)
  40 {
  41     CPUDebug *s = container_of(info, CPUDebug, info);
  42
  43     cpu_memory_rw_debug(s->cpu, memaddr, myaddr, length, 0);
  44     return 0;
  45 }
  46
  47 /* Print an error message.  We can assume that this is in response to
  48    an error return from buffer_read_memory.  */
  49 void
  50 perror_memory (int status, bfd_vma memaddr, struct disassemble_info *info)
  51 {
  52   if (status != EIO)
  53     /* Can't happen.  */
  54     (*info->fprintf_func) (info->stream, "Unknown error %d\n", status);
  55   else
  56     /* Actually, address between memaddr and memaddr + len was
  57        out of bounds.  */
  58     (*info->fprintf_func) (info->stream,
  59                            "Address 0x%" PRIx64 " is out of bounds.\n", memaddr);
  60 }
  61
  62 /* This could be in a separate file, to save minuscule amounts of space
  63    in statically linked executables.  */
  64
  65 /* Just print the address is hex.  This is included for completeness even
  66    though both GDB and objdump provide their own (to print symbolic
  67    addresses).  */
  68
  69 void
  70 generic_print_address (bfd_vma addr, struct disassemble_info *info)
  71 {
  72     (*info->fprintf_func) (info->stream, "0x%" PRIx64, addr);
  73 }
  74
  75 /* Print address in hex, truncated to the width of a host virtual address. */
  76 static void
  77 generic_print_host_address(bfd_vma addr, struct disassemble_info *info)
  78 {
  79     uint64_t mask = ~0ULL >> (64 - (sizeof(void *) * 8));
  80     generic_print_address(addr & mask, info);
  81 }
  82
  83 /* Just return the given address.  */
  84
  85 int
  86 generic_symbol_at_address (bfd_vma addr, struct disassemble_info *info)
  87 {
  88   return 1;
  89 }
  90
  91 bfd_vma bfd_getl64 (const bfd_byte *addr)
  92 {
  93   unsigned long long v;
  94
  95   v = (unsigned long long) addr[0];
  96   v |= (unsigned long long) addr[1] << 8;
  97   v |= (unsigned long long) addr[2] << 16;
  98   v |= (unsigned long long) addr[3] << 24;
  99   v |= (unsigned long long) addr[4] << 32;
 100   v |= (unsigned long long) addr[5] << 40;
 101   v |= (unsigned long long) addr[6] << 48;
 102   v |= (unsigned long long) addr[7] << 56;
 103   return (bfd_vma) v;
 104 }
 105
 106 bfd_vma bfd_getl32 (const bfd_byte *addr)
 107 {
 108   unsigned long v;
 109
 110   v = (unsigned long) addr[0];
 111   v |= (unsigned long) addr[1] << 8;
 112   v |= (unsigned long) addr[2] << 16;
 113   v |= (unsigned long) addr[3] << 24;
 114   return (bfd_vma) v;
 115 }
 116
 117 bfd_vma bfd_getb32 (const bfd_byte *addr)
 118 {
 119   unsigned long v;
 120
 121   v = (unsigned long) addr[0] << 24;
 122   v |= (unsigned long) addr[1] << 16;
 123   v |= (unsigned long) addr[2] << 8;
 124   v |= (unsigned long) addr[3];
 125   return (bfd_vma) v;
 126 }
 127
 128 bfd_vma bfd_getl16 (const bfd_byte *addr)
 129 {
 130   unsigned long v;
 131
 132   v = (unsigned long) addr[0];
 133   v |= (unsigned long) addr[1] << 8;
 134   return (bfd_vma) v;
 135 }
 136
 137 bfd_vma bfd_getb16 (const bfd_byte *addr)
 138 {
 139   unsigned long v;
 140
 141   v = (unsigned long) addr[0] << 24;
 142   v |= (unsigned long) addr[1] << 16;
 143   return (bfd_vma) v;
 144 }
 145
 146 static int print_insn_objdump(bfd_vma pc, disassemble_info *info,
 147                               const char *prefix)
 148 {
 149     int i, n = info->buffer_length;
 150     uint8_t *buf = g_malloc(n);
 151
 152     info->read_memory_func(pc, buf, n, info);
 153
 154     for (i = 0; i < n; ++i) {
 155         if (i % 32 == 0) {
 156             info->fprintf_func(info->stream, "\n%s: ", prefix);
 157         }
 158         info->fprintf_func(info->stream, "%02x", buf[i]);
 159     }
 160
 161     g_free(buf);
 162     return n;
 163 }
 164
 165 static int print_insn_od_host(bfd_vma pc, disassemble_info *info)
 166 {
 167     return print_insn_objdump(pc, info, "OBJD-H");
 168 }
 169
 170 static int print_insn_od_target(bfd_vma pc, disassemble_info *info)
 171 {
 172     return print_insn_objdump(pc, info, "OBJD-T");
 173 }
 174
 175 #ifdef CONFIG_CAPSTONE
 176 /* Temporary storage for the capstone library.  This will be alloced via
 177    malloc with a size private to the library; thus there's no reason not
 178    to share this across calls and across host vs target disassembly.  */
 179 static __thread cs_insn *cap_insn;
 180
 181 /* Initialize the Capstone library.  */
 182 /* ??? It would be nice to cache this.  We would need one handle for the
 183    host and one for the target.  For most targets we can reset specific
 184    parameters via cs_option(CS_OPT_MODE, new_mode), but we cannot change
 185    CS_ARCH_* in this way.  Thus we would need to be able to close and
 186    re-open the target handle with a different arch for the target in order
 187    to handle AArch64 vs AArch32 mode switching.  */
 188 static cs_err cap_disas_start(disassemble_info *info, csh *handle)
 189 {
 190     cs_mode cap_mode = info->cap_mode;
 191     cs_err err;
 192
 193     cap_mode += (info->endian == BFD_ENDIAN_BIG ? CS_MODE_BIG_ENDIAN
 194                  : CS_MODE_LITTLE_ENDIAN);
 195
 196     err = cs_open(info->cap_arch, cap_mode, handle);
 197     if (err != CS_ERR_OK) {
 198         return err;
 199     }
 200
 201     /* ??? There probably ought to be a better place to put this.  */
 202     if (info->cap_arch == CS_ARCH_X86) {
 203         /* We don't care about errors (if for some reason the library
 204            is compiled without AT&T syntax); the user will just have
 205            to deal with the Intel syntax.  */
 206         cs_option(*handle, CS_OPT_SYNTAX, CS_OPT_SYNTAX_ATT);
 207     }
 208
 209     /* "Disassemble" unknown insns as ".byte W,X,Y,Z".  */
 210     cs_option(*handle, CS_OPT_SKIPDATA, CS_OPT_ON);
 211
 212     /* Allocate temp space for cs_disasm_iter.  */
 213     if (cap_insn == NULL) {
 214         cap_insn = cs_malloc(*handle);
 215         if (cap_insn == NULL) {
 216             cs_close(handle);
 217             return CS_ERR_MEM;
 218         }
 219     }
 220     return CS_ERR_OK;
 221 }
 222
 223 static void cap_dump_insn_units(disassemble_info *info, cs_insn *insn,
 224                                 int i, int n)
 225 {
 226     fprintf_function print = info->fprintf_func;
 227     FILE *stream = info->stream;
 228
 229     switch (info->cap_insn_unit) {
 230     case 4:
 231         if (info->endian == BFD_ENDIAN_BIG) {
 232             for (; i < n; i += 4) {
 233                 print(stream, " %08x", ldl_be_p(insn->bytes + i));
 234
 235             }
 236         } else {
 237             for (; i < n; i += 4) {
 238                 print(stream, " %08x", ldl_le_p(insn->bytes + i));
 239             }
 240         }
 241         break;
 242
 243     case 2:
 244         if (info->endian == BFD_ENDIAN_BIG) {
 245             for (; i < n; i += 2) {
 246                 print(stream, " %04x", lduw_be_p(insn->bytes + i));
 247             }
 248         } else {
 249             for (; i < n; i += 2) {
 250                 print(stream, " %04x", lduw_le_p(insn->bytes + i));
 251             }
 252         }
 253         break;
 254
 255     default:
 256         for (; i < n; i++) {
 257             print(stream, " %02x", insn->bytes[i]);
 258         }
 259         break;
 260     }
 261 }
 262
 263 static void cap_dump_insn(disassemble_info *info, cs_insn *insn)
 264 {
 265     fprintf_function print = info->fprintf_func;
 266     int i, n, split;
 267
 268     print(info->stream, "0x%08" PRIx64 ": ", insn->address);
 269
 270     n = insn->size;
 271     split = info->cap_insn_split;
 272
 273     /* Dump the first SPLIT bytes of the instruction.  */
 274     cap_dump_insn_units(info, insn, 0, MIN(n, split));
 275
 276     /* Add padding up to SPLIT so that mnemonics line up.  */
 277     if (n < split) {
 278         int width = (split - n) / info->cap_insn_unit;
 279         width *= (2 * info->cap_insn_unit + 1);
 280         print(info->stream, "%*s", width, "");
 281     }
 282
 283     /* Print the actual instruction.  */
 284     print(info->stream, "  %-8s %s\n", insn->mnemonic, insn->op_str);
 285
 286     /* Dump any remaining part of the insn on subsequent lines.  */
 287     for (i = split; i < n; i += split) {
 288         print(info->stream, "0x%08" PRIx64 ": ", insn->address + i);
 289         cap_dump_insn_units(info, insn, i, MIN(n, i + split));
 290         print(info->stream, "\n");
 291     }
 292 }
 293
 294 /* Disassemble SIZE bytes at PC for the target.  */
 295 static bool cap_disas_target(disassemble_info *info, uint64_t pc, size_t size)
 296 {
 297     uint8_t cap_buf[1024];
 298     csh handle;
 299     cs_insn *insn;
 300     size_t csize = 0;
 301
 302     if (cap_disas_start(info, &handle) != CS_ERR_OK) {
 303         return false;
 304     }
 305     insn = cap_insn;
 306
 307     while (1) {
 308         size_t tsize = MIN(sizeof(cap_buf) - csize, size);
 309         const uint8_t *cbuf = cap_buf;
 310
 311         target_read_memory(pc + csize, cap_buf + csize, tsize, info);
 312         csize += tsize;
 313         size -= tsize;
 314
 315         while (cs_disasm_iter(handle, &cbuf, &csize, &pc, insn)) {
 316            cap_dump_insn(info, insn);
 317         }
 318
 319         /* If the target memory is not consumed, go back for more... */
 320         if (size != 0) {
 321             /* ... taking care to move any remaining fractional insn
 322                to the beginning of the buffer.  */
 323             if (csize != 0) {
 324                 memmove(cap_buf, cbuf, csize);
 325             }
 326             continue;
 327         }
 328
 329         /* Since the target memory is consumed, we should not have
 330            a remaining fractional insn.  */
 331         if (csize != 0) {
 332             (*info->fprintf_func)(info->stream,
 333                 "Disassembler disagrees with translator "
 334                 "over instruction decoding\n"
 335                 "Please report this to qemu-devel@nongnu.org\n");
 336         }
 337         break;
 338     }
 339
 340     cs_close(&handle);
 341     return true;
 342 }
 343
 344 /* Disassemble SIZE bytes at CODE for the host.  */
 345 static bool cap_disas_host(disassemble_info *info, void *code, size_t size)
 346 {
 347     csh handle;
 348     const uint8_t *cbuf;
 349     cs_insn *insn;
 350     uint64_t pc;
 351
 352     if (cap_disas_start(info, &handle) != CS_ERR_OK) {
 353         return false;
 354     }
 355     insn = cap_insn;
 356
 357     cbuf = code;
 358     pc = (uintptr_t)code;
 359
 360     while (cs_disasm_iter(handle, &cbuf, &size, &pc, insn)) {
 361        cap_dump_insn(info, insn);
 362     }
 363     if (size != 0) {
 364         (*info->fprintf_func)(info->stream,
 365             "Disassembler disagrees with TCG over instruction encoding\n"
 366             "Please report this to qemu-devel@nongnu.org\n");
 367     }
 368
 369     cs_close(&handle);
 370     return true;
 371 }
 372
 373 #if !defined(CONFIG_USER_ONLY)
 374 /* Disassemble COUNT insns at PC for the target.  */
 375 static bool cap_disas_monitor(disassemble_info *info, uint64_t pc, int count)
 376 {
 377     uint8_t cap_buf[32];
 378     csh handle;
 379     cs_insn *insn;
 380     size_t csize = 0;
 381
 382     if (cap_disas_start(info, &handle) != CS_ERR_OK) {
 383         return false;
 384     }
 385     insn = cap_insn;
 386
 387     while (1) {
 388         /* We want to read memory for one insn, but generically we do not
 389            know how much memory that is.  We have a small buffer which is
 390            known to be sufficient for all supported targets.  Try to not
 391            read beyond the page, Just In Case.  For even more simplicity,
 392            ignore the actual target page size and use a 1k boundary.  If
 393            that turns out to be insufficient, we'll come back around the
 394            loop and read more.  */
 395         uint64_t epc = QEMU_ALIGN_UP(pc + csize + 1, 1024);
 396         size_t tsize = MIN(sizeof(cap_buf) - csize, epc - pc);
 397         const uint8_t *cbuf = cap_buf;
 398
 399         /* Make certain that we can make progress.  */
 400         assert(tsize != 0);
 401         info->read_memory_func(pc, cap_buf + csize, tsize, info);
 402         csize += tsize;
 403
 404         if (cs_disasm_iter(handle, &cbuf, &csize, &pc, insn)) {
 405             cap_dump_insn(info, insn);
 406             if (--count <= 0) {
 407                 break;
 408             }
 409         }
 410         memmove(cap_buf, cbuf, csize);
 411     }
 412
 413     cs_close(&handle);
 414     return true;
 415 }
 416 #endif /* !CONFIG_USER_ONLY */
 417 #else
 418 # define cap_disas_target(i, p, s)  false
 419 # define cap_disas_host(i, p, s)  false
 420 # define cap_disas_monitor(i, p, c)  false
 421 #endif /* CONFIG_CAPSTONE */
 422
 423 /* Disassemble this for me please... (debugging).  */
 424 void target_disas(FILE *out, CPUState *cpu, target_ulong code,
 425                   target_ulong size)
 426 {
 427     CPUClass *cc = CPU_GET_CLASS(cpu);
 428     target_ulong pc;
 429     int count;
 430     CPUDebug s;
 431
 432     INIT_DISASSEMBLE_INFO(s.info, out, fprintf);
 433
 434     s.cpu = cpu;
 435     s.info.read_memory_func = target_read_memory;
 436     s.info.buffer_vma = code;
 437     s.info.buffer_length = size;
 438     s.info.print_address_func = generic_print_address;
 439     s.info.cap_arch = -1;
 440     s.info.cap_mode = 0;
 441     s.info.cap_insn_unit = 4;
 442     s.info.cap_insn_split = 4;
 443
 444 #ifdef TARGET_WORDS_BIGENDIAN
 445     s.info.endian = BFD_ENDIAN_BIG;
 446 #else
 447     s.info.endian = BFD_ENDIAN_LITTLE;
 448 #endif
 449
 450     if (cc->disas_set_info) {
 451         cc->disas_set_info(cpu, &s.info);
 452     }
 453
 454     if (s.info.cap_arch >= 0 && cap_disas_target(&s.info, code, size)) {
 455         return;
 456     }
 457
 458     if (s.info.print_insn == NULL) {
 459         s.info.print_insn = print_insn_od_target;
 460     }
 461
 462     for (pc = code; size > 0; pc += count, size -= count) {
 463         fprintf(out, "0x" TARGET_FMT_lx ":  ", pc);
 464         count = s.info.print_insn(pc, &s.info);
 465         fprintf(out, "\n");
 466         if (count < 0)
 467             break;
 468         if (size < count) {
 469             fprintf(out,
 470                     "Disassembler disagrees with translator over instruction "
 471                     "decoding\n"
 472                     "Please report this to qemu-devel@nongnu.org\n");
 473             break;
 474         }
 475     }
 476 }
 477
 478 /* Disassemble this for me please... (debugging). */
 479 void disas(FILE *out, void *code, unsigned long size)
 480 {
 481     uintptr_t pc;
 482     int count;
 483     CPUDebug s;
 484     int (*print_insn)(bfd_vma pc, disassemble_info *info) = NULL;
 485
 486     INIT_DISASSEMBLE_INFO(s.info, out, fprintf);
 487     s.info.print_address_func = generic_print_host_address;
 488
 489     s.info.buffer = code;
 490     s.info.buffer_vma = (uintptr_t)code;
 491     s.info.buffer_length = size;
 492     s.info.cap_arch = -1;
 493     s.info.cap_mode = 0;
 494     s.info.cap_insn_unit = 4;
 495     s.info.cap_insn_split = 4;
 496
 497 #ifdef HOST_WORDS_BIGENDIAN
 498     s.info.endian = BFD_ENDIAN_BIG;
 499 #else
 500     s.info.endian = BFD_ENDIAN_LITTLE;
 501 #endif
 502 #if defined(CONFIG_TCG_INTERPRETER)
 503     print_insn = print_insn_tci;
 504 #elif defined(__i386__)
 505     s.info.mach = bfd_mach_i386_i386;
 506     print_insn = print_insn_i386;
 507     s.info.cap_arch = CS_ARCH_X86;
 508     s.info.cap_mode = CS_MODE_32;
 509     s.info.cap_insn_unit = 1;
 510     s.info.cap_insn_split = 8;
 511 #elif defined(__x86_64__)
 512     s.info.mach = bfd_mach_x86_64;
 513     print_insn = print_insn_i386;
 514     s.info.cap_arch = CS_ARCH_X86;
 515     s.info.cap_mode = CS_MODE_64;
 516     s.info.cap_insn_unit = 1;
 517     s.info.cap_insn_split = 8;
 518 #elif defined(_ARCH_PPC)
 519     s.info.disassembler_options = (char *)"any";
 520     print_insn = print_insn_ppc;
 521     s.info.cap_arch = CS_ARCH_PPC;
 522 # ifdef _ARCH_PPC64
 523     s.info.cap_mode = CS_MODE_64;
 524 # endif
 525 #elif defined(__riscv) && defined(CONFIG_RISCV_DIS)
 526 #if defined(_ILP32) || (__riscv_xlen == 32)
 527     print_insn = print_insn_riscv32;
 528 #elif defined(_LP64)
 529     print_insn = print_insn_riscv64;
 530 #else
 531 #error unsupported RISC-V ABI
 532 #endif
 533 #elif defined(__aarch64__) && defined(CONFIG_ARM_A64_DIS)
 534     print_insn = print_insn_arm_a64;
 535     s.info.cap_arch = CS_ARCH_ARM64;
 536 #elif defined(__alpha__)
 537     print_insn = print_insn_alpha;
 538 #elif defined(__sparc__)
 539     print_insn = print_insn_sparc;
 540     s.info.mach = bfd_mach_sparc_v9b;
 541 #elif defined(__arm__)
 542     print_insn = print_insn_arm;
 543     s.info.cap_arch = CS_ARCH_ARM;
 544     /* TCG only generates code for arm mode.  */
 545 #elif defined(__MIPSEB__)
 546     print_insn = print_insn_big_mips;
 547 #elif defined(__MIPSEL__)
 548     print_insn = print_insn_little_mips;
 549 #elif defined(__m68k__)
 550     print_insn = print_insn_m68k;
 551 #elif defined(__s390__)
 552     print_insn = print_insn_s390;
 553 #elif defined(__hppa__)
 554     print_insn = print_insn_hppa;
 555 #endif
 556
 557     if (s.info.cap_arch >= 0 && cap_disas_host(&s.info, code, size)) {
 558         return;
 559     }
 560
 561     if (print_insn == NULL) {
 562         print_insn = print_insn_od_host;
 563     }
 564     for (pc = (uintptr_t)code; size > 0; pc += count, size -= count) {
 565         fprintf(out, "0x%08" PRIxPTR ":  ", pc);
 566         count = print_insn(pc, &s.info);
 567         fprintf(out, "\n");
 568         if (count < 0)
 569             break;
 570     }
 571 }
 572
 573 /* Look up symbol for debugging purpose.  Returns "" if unknown. */
 574 const char *lookup_symbol(target_ulong orig_addr)
 575 {
 576     const char *symbol = "";
 577     struct syminfo *s;
 578
 579     for (s = syminfos; s; s = s->next) {
 580         symbol = s->lookup_symbol(s, orig_addr);
 581         if (symbol[0] != '\0') {
 582             break;
 583         }
 584     }
 585
 586     return symbol;
 587 }
 588
 589 #if !defined(CONFIG_USER_ONLY)
 590
 591 #include "monitor/monitor.h"
 592
 593 static int
 594 physical_read_memory(bfd_vma memaddr, bfd_byte *myaddr, int length,
 595                      struct disassemble_info *info)
 596 {
 597     CPUDebug *s = container_of(info, CPUDebug, info);
 598
 599     address_space_read(s->cpu->as, memaddr, MEMTXATTRS_UNSPECIFIED,
 600                        myaddr, length);
 601     return 0;
 602 }
 603
 604 /* Disassembler for the monitor.  */
 605 void monitor_disas(Monitor *mon, CPUState *cpu,
 606                    target_ulong pc, int nb_insn, int is_physical)
 607 {
 608     CPUClass *cc = CPU_GET_CLASS(cpu);
 609     int count, i;
 610     CPUDebug s;
 611
 612     INIT_DISASSEMBLE_INFO(s.info, (FILE *)mon, monitor_fprintf);
 613
 614     s.cpu = cpu;
 615     s.info.read_memory_func
 616         = (is_physical ? physical_read_memory : target_read_memory);
 617     s.info.print_address_func = generic_print_address;
 618     s.info.buffer_vma = pc;
 619     s.info.cap_arch = -1;
 620     s.info.cap_mode = 0;
 621     s.info.cap_insn_unit = 4;
 622     s.info.cap_insn_split = 4;
 623
 624 #ifdef TARGET_WORDS_BIGENDIAN
 625     s.info.endian = BFD_ENDIAN_BIG;
 626 #else
 627     s.info.endian = BFD_ENDIAN_LITTLE;
 628 #endif
 629
 630     if (cc->disas_set_info) {
 631         cc->disas_set_info(cpu, &s.info);
 632     }
 633
 634     if (s.info.cap_arch >= 0 && cap_disas_monitor(&s.info, pc, nb_insn)) {
 635         return;
 636     }
 637
 638     if (!s.info.print_insn) {
 639         monitor_printf(mon, "0x" TARGET_FMT_lx
 640                        ": Asm output not supported on this arch\n", pc);
 641         return;
 642     }
 643
 644     for(i = 0; i < nb_insn; i++) {
 645         monitor_printf(mon, "0x" TARGET_FMT_lx ":  ", pc);
 646         count = s.info.print_insn(pc, &s.info);
 647         monitor_printf(mon, "\n");
 648         if (count < 0)
 649             break;
 650         pc += count;
 651     }
 652 }
 653 #endif