riscv/gdbserver.cc

   1 #include <arpa/inet.h>
   2 #include <errno.h>
   3 #include <fcntl.h>
   4 #include <stdlib.h>
   5 #include <string.h>
   6 #include <sys/socket.h>
   7 #include <sys/types.h>
   8 #include <unistd.h>
   9
  10 #include <algorithm>
  11 #include <cassert>
  12 #include <cstdio>
  13 #include <vector>
  14
  15 #include "disasm.h"
  16 #include "sim.h"
  17 #include "gdbserver.h"
  18 #include "mmu.h"
  19
  20 #define C_EBREAK        0x9002
  21 #define EBREAK          0x00100073
  22
  23 //////////////////////////////////////// Utility Functions
  24
  25 void die(const char* msg)
  26 {
  27   fprintf(stderr, "gdbserver code died: %s\n", msg);
  28   abort();
  29 }
  30
  31 // gdb's register list is defined in riscv_gdb_reg_names gdb/riscv-tdep.c in
  32 // its source tree. We must interpret the numbers the same here.
  33 enum {
  34   REG_XPR0 = 0,
  35   REG_XPR31 = 31,
  36   REG_PC = 32,
  37   REG_FPR0 = 33,
  38   REG_FPR31 = 64,
  39   REG_CSR0 = 65,
  40   REG_CSR4095 = 4160,
  41   REG_END = 4161
  42 };
  43
  44 //////////////////////////////////////// Functions to generate RISC-V opcodes.
  45
  46 // TODO: Does this already exist somewhere?
  47
  48 // Using regnames.cc as source. The RVG Calling Convention of the 2.0 RISC-V
  49 // spec says it should be 2 and 3.
  50 #define S0      8
  51 #define S1      9
  52 static uint32_t bits(uint32_t value, unsigned int hi, unsigned int lo) {
  53   return (value >> lo) & ((1 << (hi+1-lo)) - 1);
  54 }
  55
  56 static uint32_t bit(uint32_t value, unsigned int b) {
  57   return (value >> b) & 1;
  58 }
  59
  60 static uint32_t jal(unsigned int rd, uint32_t imm) {
  61   return (bit(imm, 20) << 31) |
  62     (bits(imm, 10, 1) << 21) |
  63     (bit(imm, 11) << 20) |
  64     (bits(imm, 19, 12) << 12) |
  65     (rd << 7) |
  66     MATCH_JAL;
  67 }
  68
  69 static uint32_t csrsi(unsigned int csr, uint8_t imm) {
  70   return (csr << 20) |
  71     (bits(imm, 4, 0) << 15) |
  72     MATCH_CSRRSI;
  73 }
  74
  75 static uint32_t csrci(unsigned int csr, uint8_t imm) {
  76   return (csr << 20) |
  77     (bits(imm, 4, 0) << 15) |
  78     MATCH_CSRRCI;
  79 }
  80
  81 static uint32_t csrr(unsigned int rd, unsigned int csr) {
  82   return (csr << 20) | (rd << 7) | MATCH_CSRRS;
  83 }
  84
  85 static uint32_t sw(unsigned int src, unsigned int base, uint16_t offset)
  86 {
  87   return (bits(offset, 11, 5) << 25) |
  88     (src << 20) |
  89     (base << 15) |
  90     (bits(offset, 4, 0) << 7) |
  91     MATCH_SW;
  92 }
  93
  94 static uint32_t sd(unsigned int src, unsigned int base, uint16_t offset)
  95 {
  96   return (bits(offset, 11, 5) << 25) |
  97     (bits(src, 4, 0) << 20) |
  98     (base << 15) |
  99     (bits(offset, 4, 0) << 7) |
 100     MATCH_SD;
 101 }
 102
 103 static uint32_t fsd(unsigned int src, unsigned int base, uint16_t offset)
 104 {
 105   return (bits(offset, 11, 5) << 25) |
 106     (bits(src, 4, 0) << 20) |
 107     (base << 15) |
 108     (bits(offset, 4, 0) << 7) |
 109     MATCH_FSD;
 110 }
 111
 112 static uint32_t addi(unsigned int dest, unsigned int src, uint16_t imm)
 113 {
 114   return (bits(imm, 11, 0) << 20) |
 115     (src << 15) |
 116     (dest << 7) |
 117     MATCH_ADDI;
 118 }
 119
 120 static uint32_t nop()
 121 {
 122   return addi(0, 0, 0);
 123 }
 124
 125 template <typename T>
 126 unsigned int circular_buffer_t<T>::size() const
 127 {
 128   if (end >= start)
 129     return end - start;
 130   else
 131     return end + capacity - start;
 132 }
 133
 134 template <typename T>
 135 void circular_buffer_t<T>::consume(unsigned int bytes)
 136 {
 137   start = (start + bytes) % capacity;
 138 }
 139
 140 template <typename T>
 141 unsigned int circular_buffer_t<T>::contiguous_empty_size() const
 142 {
 143   if (end >= start)
 144     if (start == 0)
 145       return capacity - end - 1;
 146     else
 147       return capacity - end;
 148   else
 149     return start - end - 1;
 150 }
 151
 152 template <typename T>
 153 unsigned int circular_buffer_t<T>::contiguous_data_size() const
 154 {
 155   if (end >= start)
 156     return end - start;
 157   else
 158     return capacity - start;
 159 }
 160
 161 template <typename T>
 162 void circular_buffer_t<T>::data_added(unsigned int bytes)
 163 {
 164   end += bytes;
 165   assert(end <= capacity);
 166   if (end == capacity)
 167     end = 0;
 168 }
 169
 170 template <typename T>
 171 void circular_buffer_t<T>::reset()
 172 {
 173   start = 0;
 174   end = 0;
 175 }
 176
 177 template <typename T>
 178 void circular_buffer_t<T>::append(const T *src, unsigned int count)
 179 {
 180   unsigned int copy = std::min(count, contiguous_empty_size());
 181   memcpy(contiguous_empty(), src, copy * sizeof(T));
 182   data_added(copy);
 183   count -= copy;
 184   if (count > 0) {
 185     assert(count < contiguous_empty_size());
 186     memcpy(contiguous_empty(), src, count * sizeof(T));
 187     data_added(count);
 188   }
 189 }
 190
 191 ////////////////////////////// Debug Operations
 192
 193 class halt_op_t : public operation_t
 194 {
 195   public:
 196     halt_op_t(gdbserver_t& gdbserver) : operation_t(gdbserver) {};
 197
 198     bool start()
 199     {
 200       // TODO: For now we just assume the target is 64-bit.
 201       gs.write_debug_ram(0, csrsi(DCSR_ADDRESS, DCSR_HALT_MASK));
 202       gs.write_debug_ram(1, csrr(S0, DPC_ADDRESS));
 203       gs.write_debug_ram(2, sd(S0, 0, (uint16_t) DEBUG_RAM_START));
 204       gs.write_debug_ram(3, csrr(S0, DCSR_ADDRESS));
 205       gs.write_debug_ram(4, sd(S0, 0, (uint16_t) DEBUG_RAM_START + 8));
 206       gs.write_debug_ram(5, jal(0, (uint32_t) (DEBUG_ROM_RESUME - (DEBUG_RAM_START + 4*5))));
 207       gs.set_interrupt(0);
 208       return false;
 209     }
 210
 211     bool step()
 212     {
 213       return true;
 214     }
 215 };
 216
 217 class general_registers_read_op_t : public operation_t
 218 {
 219   // Register order that gdb expects is:
 220   //   "x0",  "x1",  "x2",  "x3",  "x4",  "x5",  "x6",  "x7",
 221   //   "x8",  "x9",  "x10", "x11", "x12", "x13", "x14", "x15",
 222   //   "x16", "x17", "x18", "x19", "x20", "x21", "x22", "x23",
 223   //   "x24", "x25", "x26", "x27", "x28", "x29", "x30", "x31",
 224
 225   // Each byte of register data is described by two hex digits. The bytes with
 226   // the register are transmitted in target byte order. The size of each
 227   // register and their position within the ‘g’ packet are determined by the
 228   // gdb internal gdbarch functions DEPRECATED_REGISTER_RAW_SIZE and
 229   // gdbarch_register_name.
 230
 231   public:
 232     general_registers_read_op_t(gdbserver_t& gdbserver) :
 233       operation_t(gdbserver), current_reg(0) {};
 234
 235     bool start()
 236     {
 237       gs.start_packet();
 238
 239       // x0 is always zero.
 240       gs.send((reg_t) 0);
 241
 242       gs.write_debug_ram(0, sd(1, 0, (uint16_t) DEBUG_RAM_START + 16));
 243       gs.write_debug_ram(1, sd(2, 0, (uint16_t) DEBUG_RAM_START + 0));
 244       gs.write_debug_ram(2, jal(0, (uint32_t) (DEBUG_ROM_RESUME - (DEBUG_RAM_START + 4*2))));
 245       gs.set_interrupt(0);
 246       current_reg = 1;
 247       return false;
 248     }
 249
 250     bool step()
 251     {
 252       fprintf(stderr, "step %d\n", current_reg);
 253       gs.send(((uint64_t) gs.read_debug_ram(5) << 32) | gs.read_debug_ram(4));
 254       if (current_reg >= 31) {
 255         gs.end_packet();
 256         return true;
 257       }
 258
 259       gs.send(((uint64_t) gs.read_debug_ram(1) << 32) | gs.read_debug_ram(0));
 260
 261       current_reg += 2;
 262       // TODO properly read s0 and s1
 263       gs.write_debug_ram(0, sd(current_reg, 0, (uint16_t) DEBUG_RAM_START + 16));
 264       gs.write_debug_ram(1, sd(current_reg+1, 0, (uint16_t) DEBUG_RAM_START + 0));
 265       gs.write_debug_ram(2, jal(0, (uint32_t) (DEBUG_ROM_RESUME - (DEBUG_RAM_START + 4*2))));
 266       gs.set_interrupt(0);
 267
 268       return false;
 269     }
 270
 271   private:
 272     unsigned int current_reg;
 273 };
 274
 275 class register_read_op_t : public operation_t
 276 {
 277   public:
 278     register_read_op_t(gdbserver_t& gdbserver, unsigned int reg) :
 279       operation_t(gdbserver), reg(reg) {};
 280
 281     bool start()
 282     {
 283       if (reg >= REG_XPR0 && reg <= REG_XPR31) {
 284         die("handle_register_read");
 285         // send(p->state.XPR[reg - REG_XPR0]);
 286       } else if (reg == REG_PC) {
 287         gs.write_debug_ram(0, csrr(S0, DPC_ADDRESS));
 288         gs.write_debug_ram(1, sd(S0, 0, (uint16_t) DEBUG_RAM_START + 16));
 289         gs.write_debug_ram(2, jal(0, (uint32_t) (DEBUG_ROM_RESUME - (DEBUG_RAM_START + 4*2))));
 290       } else if (reg >= REG_FPR0 && reg <= REG_FPR31) {
 291         // send(p->state.FPR[reg - REG_FPR0]);
 292         gs.write_debug_ram(0, fsd(reg - REG_FPR0, 0, (uint16_t) DEBUG_RAM_START + 16));
 293         gs.write_debug_ram(1, jal(0, (uint32_t) (DEBUG_ROM_RESUME - (DEBUG_RAM_START + 4*1))));
 294       } else if (reg >= REG_CSR0 && reg <= REG_CSR4095) {
 295         gs.write_debug_ram(0, csrr(S0, reg - REG_CSR0));
 296         gs.write_debug_ram(1, sd(S0, 0, (uint16_t) DEBUG_RAM_START + 16));
 297         gs.write_debug_ram(2, jal(0, (uint32_t) (DEBUG_ROM_RESUME - (DEBUG_RAM_START + 4*2))));
 298       } else {
 299         gs.send_packet("E02");
 300         return true;
 301       }
 302
 303       gs.set_interrupt(0);
 304
 305       return false;
 306     }
 307
 308     bool step()
 309     {
 310       gs.start_packet();
 311       gs.send(((uint64_t) gs.read_debug_ram(5) << 32) | gs.read_debug_ram(4));
 312       gs.end_packet();
 313       return true;
 314     }
 315
 316   private:
 317     unsigned int reg;
 318 };
 319
 320 ////////////////////////////// gdbserver itself
 321
 322 gdbserver_t::gdbserver_t(uint16_t port, sim_t *sim) :
 323   sim(sim),
 324   client_fd(0),
 325   recv_buf(64 * 1024), send_buf(64 * 1024),
 326   operation(NULL)
 327 {
 328   socket_fd = socket(AF_INET, SOCK_STREAM, 0);
 329   if (socket_fd == -1) {
 330     fprintf(stderr, "failed to make socket: %s (%d)\n", strerror(errno), errno);
 331     abort();
 332   }
 333
 334   fcntl(socket_fd, F_SETFL, O_NONBLOCK);
 335   int reuseaddr = 1;
 336   if (setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, &reuseaddr,
 337         sizeof(int)) == -1) {
 338     fprintf(stderr, "failed setsockopt: %s (%d)\n", strerror(errno), errno);
 339     abort();
 340   }
 341
 342   struct sockaddr_in addr;
 343   memset(&addr, 0, sizeof(addr));
 344   addr.sin_family = AF_INET;
 345   addr.sin_addr.s_addr = INADDR_ANY;
 346   addr.sin_port = htons(port);
 347
 348   if (bind(socket_fd, (struct sockaddr *) &addr, sizeof(addr)) == -1) {
 349     fprintf(stderr, "failed to bind socket: %s (%d)\n", strerror(errno), errno);
 350     abort();
 351   }
 352
 353   if (listen(socket_fd, 1) == -1) {
 354     fprintf(stderr, "failed to listen on socket: %s (%d)\n", strerror(errno), errno);
 355     abort();
 356   }
 357 }
 358
 359 void gdbserver_t::write_debug_ram(unsigned int index, uint32_t value)
 360 {
 361   sim->debug_module.ram_write32(index, value);
 362 }
 363
 364 uint32_t gdbserver_t::read_debug_ram(unsigned int index)
 365 {
 366   return sim->debug_module.ram_read32(index);
 367 }
 368
 369 void gdbserver_t::set_operation(operation_t* operation)
 370 {
 371   assert(this->operation == NULL || operation == NULL);
 372   if (operation && operation->start()) {
 373     delete operation;
 374   } else {
 375     this->operation = operation;
 376   }
 377 }
 378
 379 void gdbserver_t::accept()
 380 {
 381   client_fd = ::accept(socket_fd, NULL, NULL);
 382   if (client_fd == -1) {
 383     if (errno == EAGAIN) {
 384       // No client waiting to connect right now.
 385     } else {
 386       fprintf(stderr, "failed to accept on socket: %s (%d)\n", strerror(errno),
 387           errno);
 388       abort();
 389     }
 390   } else {
 391     fcntl(client_fd, F_SETFL, O_NONBLOCK);
 392
 393     expect_ack = false;
 394     extended_mode = false;
 395
 396     // gdb wants the core to be halted when it attaches.
 397     set_operation(new halt_op_t(*this));
 398   }
 399 }
 400
 401 void gdbserver_t::read()
 402 {
 403   // Reading from a non-blocking socket still blocks if there is no data
 404   // available.
 405
 406   size_t count = recv_buf.contiguous_empty_size();
 407   assert(count > 0);
 408   ssize_t bytes = ::read(client_fd, recv_buf.contiguous_empty(), count);
 409   if (bytes == -1) {
 410     if (errno == EAGAIN) {
 411       // We'll try again the next call.
 412     } else {
 413       fprintf(stderr, "failed to read on socket: %s (%d)\n", strerror(errno), errno);
 414       abort();
 415     }
 416   } else if (bytes == 0) {
 417     // The remote disconnected.
 418     client_fd = 0;
 419     processor_t *p = sim->get_core(0);
 420     // TODO p->set_halted(false, HR_NONE);
 421     recv_buf.reset();
 422     send_buf.reset();
 423   } else {
 424     recv_buf.data_added(bytes);
 425   }
 426 }
 427
 428 void gdbserver_t::write()
 429 {
 430   if (send_buf.empty())
 431     return;
 432
 433   while (!send_buf.empty()) {
 434     unsigned int count = send_buf.contiguous_data_size();
 435     assert(count > 0);
 436     ssize_t bytes = ::write(client_fd, send_buf.contiguous_data(), count);
 437     if (bytes == -1) {
 438       fprintf(stderr, "failed to write to socket: %s (%d)\n", strerror(errno), errno);
 439       abort();
 440     } else if (bytes == 0) {
 441       // Client can't take any more data right now.
 442       break;
 443     } else {
 444       fprintf(stderr, "wrote %ld bytes: ", bytes);
 445       for (unsigned int i = 0; i < bytes; i++) {
 446         fprintf(stderr, "%c", send_buf[i]);
 447       }
 448       fprintf(stderr, "\n");
 449       send_buf.consume(bytes);
 450     }
 451   }
 452 }
 453
 454 void print_packet(const std::vector<uint8_t> &packet)
 455 {
 456   for (uint8_t c : packet) {
 457     if (c >= ' ' and c <= '~')
 458       fprintf(stderr, "%c", c);
 459     else
 460       fprintf(stderr, "\\x%x", c);
 461   }
 462   fprintf(stderr, "\n");
 463 }
 464
 465 uint8_t compute_checksum(const std::vector<uint8_t> &packet)
 466 {
 467   uint8_t checksum = 0;
 468   for (auto i = packet.begin() + 1; i != packet.end() - 3; i++ ) {
 469     checksum += *i;
 470   }
 471   return checksum;
 472 }
 473
 474 uint8_t character_hex_value(uint8_t character)
 475 {
 476   if (character >= '0' && character <= '9')
 477     return character - '0';
 478   if (character >= 'a' && character <= 'f')
 479     return 10 + character - 'a';
 480   if (character >= 'A' && character <= 'F')
 481     return 10 + character - 'A';
 482   return 0xff;
 483 }
 484
 485 uint8_t extract_checksum(const std::vector<uint8_t> &packet)
 486 {
 487   return character_hex_value(*(packet.end() - 1)) +
 488     16 * character_hex_value(*(packet.end() - 2));
 489 }
 490
 491 void gdbserver_t::process_requests()
 492 {
 493   // See https://sourceware.org/gdb/onlinedocs/gdb/Remote-Protocol.html
 494
 495   while (!recv_buf.empty()) {
 496     std::vector<uint8_t> packet;
 497     for (unsigned int i = 0; i < recv_buf.size(); i++) {
 498       uint8_t b = recv_buf[i];
 499
 500       if (packet.empty() && expect_ack && b == '+') {
 501         recv_buf.consume(1);
 502         break;
 503       }
 504
 505       if (packet.empty() && b == 3) {
 506         fprintf(stderr, "Received interrupt\n");
 507         recv_buf.consume(1);
 508         handle_interrupt();
 509         break;
 510       }
 511
 512       if (b == '$') {
 513         // Start of new packet.
 514         if (!packet.empty()) {
 515           fprintf(stderr, "Received malformed %ld-byte packet from debug client: ",
 516               packet.size());
 517           print_packet(packet);
 518           recv_buf.consume(i);
 519           break;
 520         }
 521       }
 522
 523       packet.push_back(b);
 524
 525       // Packets consist of $<packet-data>#<checksum>
 526       // where <checksum> is
 527       if (packet.size() >= 4 &&
 528           packet[packet.size()-3] == '#') {
 529         handle_packet(packet);
 530         recv_buf.consume(i+1);
 531         break;
 532       }
 533     }
 534     // There's a partial packet in the buffer. Wait until we get more data to
 535     // process it.
 536     if (packet.size()) {
 537       break;
 538     }
 539   }
 540 }
 541
 542 void gdbserver_t::handle_halt_reason(const std::vector<uint8_t> &packet)
 543 {
 544   send_packet("S00");
 545 }
 546
 547 void gdbserver_t::handle_general_registers_read(const std::vector<uint8_t> &packet)
 548 {
 549   set_operation(new general_registers_read_op_t(*this));
 550 }
 551
 552 void gdbserver_t::set_interrupt(uint32_t hartid) {
 553   sim->debug_module.set_interrupt(hartid);
 554 }
 555
 556 // First byte is the most-significant one.
 557 // Eg. "08675309" becomes 0x08675309.
 558 uint64_t consume_hex_number(std::vector<uint8_t>::const_iterator &iter,
 559     std::vector<uint8_t>::const_iterator end)
 560 {
 561   uint64_t value = 0;
 562
 563   while (iter != end) {
 564     uint8_t c = *iter;
 565     uint64_t c_value = character_hex_value(c);
 566     if (c_value > 15)
 567       break;
 568     iter++;
 569     value <<= 4;
 570     value += c_value;
 571   }
 572   return value;
 573 }
 574
 575 // First byte is the least-significant one.
 576 // Eg. "08675309" becomes 0x09536708
 577 uint64_t consume_hex_number_le(std::vector<uint8_t>::const_iterator &iter,
 578     std::vector<uint8_t>::const_iterator end)
 579 {
 580   uint64_t value = 0;
 581   unsigned int shift = 4;
 582
 583   while (iter != end) {
 584     uint8_t c = *iter;
 585     uint64_t c_value = character_hex_value(c);
 586     if (c_value > 15)
 587       break;
 588     iter++;
 589     value |= c_value << shift;
 590     if ((shift % 8) == 0)
 591       shift += 12;
 592     else
 593       shift -= 4;
 594   }
 595   return value;
 596 }
 597
 598 void consume_string(std::string &str, std::vector<uint8_t>::const_iterator &iter,
 599     std::vector<uint8_t>::const_iterator end, uint8_t separator)
 600 {
 601   while (iter != end && *iter != separator) {
 602     str.append(1, (char) *iter);
 603     iter++;
 604   }
 605 }
 606
 607 void gdbserver_t::handle_register_read(const std::vector<uint8_t> &packet)
 608 {
 609   // p n
 610
 611   std::vector<uint8_t>::const_iterator iter = packet.begin() + 2;
 612   unsigned int n = consume_hex_number(iter, packet.end());
 613   if (*iter != '#')
 614     return send_packet("E01");
 615
 616   set_operation(new register_read_op_t(*this, n));
 617 }
 618
 619 void gdbserver_t::handle_register_write(const std::vector<uint8_t> &packet)
 620 {
 621   // P n...=r...
 622
 623   std::vector<uint8_t>::const_iterator iter = packet.begin() + 2;
 624   unsigned int n = consume_hex_number(iter, packet.end());
 625   if (*iter != '=')
 626     return send_packet("E05");
 627   iter++;
 628
 629   reg_t value = consume_hex_number_le(iter, packet.end());
 630   if (*iter != '#')
 631     return send_packet("E06");
 632
 633   processor_t *p = sim->get_core(0);
 634
 635   die("handle_register_write");
 636   /*
 637   if (n >= REG_XPR0 && n <= REG_XPR31) {
 638     p->state.XPR.write(n - REG_XPR0, value);
 639   } else if (n == REG_PC) {
 640     p->state.pc = value;
 641   } else if (n >= REG_FPR0 && n <= REG_FPR31) {
 642     p->state.FPR.write(n - REG_FPR0, value);
 643   } else if (n >= REG_CSR0 && n <= REG_CSR4095) {
 644     try {
 645       p->set_csr(n - REG_CSR0, value);
 646     } catch(trap_t& t) {
 647       return send_packet("EFF");
 648     }
 649   } else {
 650     return send_packet("E07");
 651   }
 652   */
 653
 654   return send_packet("OK");
 655 }
 656
 657 void gdbserver_t::handle_memory_read(const std::vector<uint8_t> &packet)
 658 {
 659   // m addr,length
 660   std::vector<uint8_t>::const_iterator iter = packet.begin() + 2;
 661   reg_t address = consume_hex_number(iter, packet.end());
 662   if (*iter != ',')
 663     return send_packet("E10");
 664   iter++;
 665   reg_t length = consume_hex_number(iter, packet.end());
 666   if (*iter != '#')
 667     return send_packet("E11");
 668
 669   start_packet();
 670   char buffer[3];
 671   processor_t *p = sim->get_core(0);
 672   mmu_t* mmu = sim->debug_mmu;
 673
 674   for (reg_t i = 0; i < length; i++) {
 675     sprintf(buffer, "%02x", mmu->load_uint8(address + i));
 676     send(buffer);
 677   }
 678   end_packet();
 679 }
 680
 681 void gdbserver_t::handle_memory_binary_write(const std::vector<uint8_t> &packet)
 682 {
 683   // X addr,length:XX...
 684   std::vector<uint8_t>::const_iterator iter = packet.begin() + 2;
 685   reg_t address = consume_hex_number(iter, packet.end());
 686   if (*iter != ',')
 687     return send_packet("E20");
 688   iter++;
 689   reg_t length = consume_hex_number(iter, packet.end());
 690   if (*iter != ':')
 691     return send_packet("E21");
 692   iter++;
 693
 694   processor_t *p = sim->get_core(0);
 695   mmu_t* mmu = sim->debug_mmu;
 696   for (unsigned int i = 0; i < length; i++) {
 697     if (iter == packet.end()) {
 698       return send_packet("E22");
 699     }
 700     mmu->store_uint8(address + i, *iter);
 701     iter++;
 702   }
 703   if (*iter != '#')
 704     return send_packet("E4b"); // EOVERFLOW
 705
 706   send_packet("OK");
 707 }
 708
 709 void gdbserver_t::handle_continue(const std::vector<uint8_t> &packet)
 710 {
 711   // c [addr]
 712   processor_t *p = sim->get_core(0);
 713   if (packet[2] != '#') {
 714     std::vector<uint8_t>::const_iterator iter = packet.begin() + 2;
 715     die("handle_continue");
 716     // p->state.pc = consume_hex_number(iter, packet.end());
 717     if (*iter != '#')
 718       return send_packet("E30");
 719   }
 720
 721   write_debug_ram(0, csrci(DCSR_ADDRESS, DCSR_HALT_MASK));
 722   write_debug_ram(1, jal(0, (uint32_t) (DEBUG_ROM_RESUME - (DEBUG_RAM_START + 1*5))));
 723   set_interrupt(0);
 724
 725   // TODO p->set_halted(false, HR_NONE);
 726   // TODO running = true;
 727 }
 728
 729 void gdbserver_t::handle_step(const std::vector<uint8_t> &packet)
 730 {
 731   // s [addr]
 732   processor_t *p = sim->get_core(0);
 733   if (packet[2] != '#') {
 734     std::vector<uint8_t>::const_iterator iter = packet.begin() + 2;
 735     die("handle_step");
 736     //p->state.pc = consume_hex_number(iter, packet.end());
 737     if (*iter != '#')
 738       return send_packet("E40");
 739   }
 740
 741   // TODO: p->set_single_step(true);
 742   // TODO running = true;
 743 }
 744
 745 void gdbserver_t::handle_kill(const std::vector<uint8_t> &packet)
 746 {
 747   // k
 748   // The exact effect of this packet is not specified.
 749   // Looks like OpenOCD disconnects?
 750   // TODO
 751 }
 752
 753 void gdbserver_t::handle_extended(const std::vector<uint8_t> &packet)
 754 {
 755   // Enable extended mode. In extended mode, the remote server is made
 756   // persistent. The ‘R’ packet is used to restart the program being debugged.
 757   send_packet("OK");
 758   extended_mode = true;
 759 }
 760
 761 void software_breakpoint_t::insert(mmu_t* mmu)
 762 {
 763   if (size == 2) {
 764     instruction = mmu->load_uint16(address);
 765     mmu->store_uint16(address, C_EBREAK);
 766   } else {
 767     instruction = mmu->load_uint32(address);
 768     mmu->store_uint32(address, EBREAK);
 769   }
 770   fprintf(stderr, ">>> Read %x from %lx\n", instruction, address);
 771 }
 772
 773 void software_breakpoint_t::remove(mmu_t* mmu)
 774 {
 775   fprintf(stderr, ">>> write %x to %lx\n", instruction, address);
 776   if (size == 2) {
 777     mmu->store_uint16(address, instruction);
 778   } else {
 779     mmu->store_uint32(address, instruction);
 780   }
 781 }
 782
 783 void gdbserver_t::handle_breakpoint(const std::vector<uint8_t> &packet)
 784 {
 785   // insert: Z type,addr,kind
 786   // remove: z type,addr,kind
 787
 788   software_breakpoint_t bp;
 789   bool insert = (packet[1] == 'Z');
 790   std::vector<uint8_t>::const_iterator iter = packet.begin() + 2;
 791   int type = consume_hex_number(iter, packet.end());
 792   if (*iter != ',')
 793     return send_packet("E50");
 794   iter++;
 795   bp.address = consume_hex_number(iter, packet.end());
 796   if (*iter != ',')
 797     return send_packet("E51");
 798   iter++;
 799   bp.size = consume_hex_number(iter, packet.end());
 800   // There may be more options after a ; here, but we don't support that.
 801   if (*iter != '#')
 802     return send_packet("E52");
 803
 804   if (bp.size != 2 && bp.size != 4) {
 805     return send_packet("E53");
 806   }
 807
 808   processor_t *p = sim->get_core(0);
 809   die("handle_breakpoint");
 810   /*
 811   mmu_t* mmu = p->mmu;
 812   if (insert) {
 813     bp.insert(mmu);
 814     breakpoints[bp.address] = bp;
 815
 816   } else {
 817     bp = breakpoints[bp.address];
 818     bp.remove(mmu);
 819     breakpoints.erase(bp.address);
 820   }
 821   mmu->flush_icache();
 822   sim->debug_mmu->flush_icache();
 823   */
 824   return send_packet("OK");
 825 }
 826
 827 void gdbserver_t::handle_query(const std::vector<uint8_t> &packet)
 828 {
 829   std::string name;
 830   std::vector<uint8_t>::const_iterator iter = packet.begin() + 2;
 831
 832   consume_string(name, iter, packet.end(), ':');
 833   if (iter != packet.end())
 834     iter++;
 835   if (name == "Supported") {
 836     start_packet();
 837     while (iter != packet.end()) {
 838       std::string feature;
 839       consume_string(feature, iter, packet.end(), ';');
 840       if (iter != packet.end())
 841         iter++;
 842       if (feature == "swbreak+") {
 843         send("swbreak+;");
 844       }
 845     }
 846     return end_packet();
 847   }
 848
 849   fprintf(stderr, "Unsupported query %s\n", name.c_str());
 850   return send_packet("");
 851 }
 852
 853 void gdbserver_t::handle_packet(const std::vector<uint8_t> &packet)
 854 {
 855   if (compute_checksum(packet) != extract_checksum(packet)) {
 856     fprintf(stderr, "Received %ld-byte packet with invalid checksum\n", packet.size());
 857     fprintf(stderr, "Computed checksum: %x\n", compute_checksum(packet));
 858     print_packet(packet);
 859     send("-");
 860     return;
 861   }
 862
 863   fprintf(stderr, "Received %ld-byte packet from debug client: ", packet.size());
 864   print_packet(packet);
 865   send("+");
 866
 867   switch (packet[1]) {
 868     case '!':
 869       return handle_extended(packet);
 870     case '?':
 871       return handle_halt_reason(packet);
 872     case 'g':
 873       return handle_general_registers_read(packet);
 874     case 'k':
 875       return handle_kill(packet);
 876     case 'm':
 877       return handle_memory_read(packet);
 878 //    case 'M':
 879 //      return handle_memory_write(packet);
 880     case 'X':
 881       return handle_memory_binary_write(packet);
 882     case 'p':
 883       return handle_register_read(packet);
 884     case 'P':
 885       return handle_register_write(packet);
 886     case 'c':
 887       return handle_continue(packet);
 888     case 's':
 889       return handle_step(packet);
 890     case 'z':
 891     case 'Z':
 892       return handle_breakpoint(packet);
 893     case 'q':
 894     case 'Q':
 895       return handle_query(packet);
 896   }
 897
 898   // Not supported.
 899   fprintf(stderr, "** Unsupported packet: ");
 900   print_packet(packet);
 901   send_packet("");
 902 }
 903
 904 void gdbserver_t::handle_interrupt()
 905 {
 906   processor_t *p = sim->get_core(0);
 907   // TODO p->set_halted(true, HR_INTERRUPT);
 908   send_packet("S02");   // Pretend program received SIGINT.
 909   // TODO running = false;
 910 }
 911
 912 void gdbserver_t::handle()
 913 {
 914   if (client_fd > 0) {
 915     processor_t *p = sim->get_core(0);
 916
 917     bool interrupt = sim->debug_module.get_interrupt(0);
 918
 919     if (!interrupt) {
 920       if (operation && operation->step()) {
 921         delete operation;
 922         set_operation(NULL);
 923       }
 924
 925       /*
 926       switch (state) {
 927         case STATE_HALTING:
 928           // gdb requested a halt and now it's done.
 929           send_packet("T05");
 930           fprintf(stderr, "DPC: 0x%x\n", read_debug_ram(0));
 931           fprintf(stderr, "DCSR: 0x%x\n", read_debug_ram(2));
 932           state = STATE_HALTED;
 933           break;
 934       }
 935       */
 936     }
 937
 938     /* TODO
 939     if (running && p->halted) {
 940       // The core was running, but now it's halted. Better tell gdb.
 941       switch (p->halt_reason) {
 942         case HR_NONE:
 943           fprintf(stderr, "Internal error. Processor halted without reason.\n");
 944           abort();
 945         case HR_STEPPED:
 946         case HR_INTERRUPT:
 947         case HR_CMDLINE:
 948         case HR_ATTACHED:
 949           // There's no gdb code for this.
 950           send_packet("T05");
 951           break;
 952         case HR_SWBP:
 953           send_packet("T05swbreak:;");
 954           break;
 955       }
 956       send_packet("T00");
 957       // TODO: Actually include register values here
 958       running = false;
 959     }
 960       */
 961
 962     this->read();
 963     this->write();
 964
 965   } else {
 966     this->accept();
 967   }
 968
 969   if (!operation) {
 970     this->process_requests();
 971   }
 972 }
 973
 974 void gdbserver_t::send(const char* msg)
 975 {
 976   unsigned int length = strlen(msg);
 977   for (const char *c = msg; *c; c++)
 978     running_checksum += *c;
 979   send_buf.append((const uint8_t *) msg, length);
 980 }
 981
 982 void gdbserver_t::send(uint64_t value)
 983 {
 984   char buffer[3];
 985   for (unsigned int i = 0; i < 8; i++) {
 986     sprintf(buffer, "%02x", (int) (value & 0xff));
 987     send(buffer);
 988     value >>= 8;
 989   }
 990 }
 991
 992 void gdbserver_t::send(uint32_t value)
 993 {
 994   char buffer[3];
 995   for (unsigned int i = 0; i < 4; i++) {
 996     sprintf(buffer, "%02x", (int) (value & 0xff));
 997     send(buffer);
 998     value >>= 8;
 999   }
1000 }
1001
1002 void gdbserver_t::send_packet(const char* data)
1003 {
1004   start_packet();
1005   send(data);
1006   end_packet();
1007   expect_ack = true;
1008 }
1009
1010 void gdbserver_t::start_packet()
1011 {
1012   send("$");
1013   running_checksum = 0;
1014 }
1015
1016 void gdbserver_t::end_packet(const char* data)
1017 {
1018   if (data) {
1019     send(data);
1020   }
1021
1022   char checksum_string[4];
1023   sprintf(checksum_string, "#%02x", running_checksum);
1024   send(checksum_string);
1025   expect_ack = true;
1026 }