Bochs/bochs/gdbstub.cc

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#ifdef __MINGW32__
#include <winsock2.h>
#define SIGTRAP 5
#else
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <signal.h>
#include <netdb.h>
#endif

#define NEED_CPU_REG_SHORTCUTS 1

#include "bochs.h"
#include "cpu/cpu.h"
#include "iodev/iodev.h"

#define LOG_THIS genlog->
#define IFDBG(x) x

static int last_stop_reason = GDBSTUB_STOP_NO_REASON;

#define GDBSTUB_EXECUTION_BREAKPOINT    (0xac1)
#define GDBSTUB_TRACE                   (0xac2)
#define GDBSTUB_USER_BREAK              (0xac3)

static bx_list_c *gdbstub_list;
static int listen_socket_fd;
static int socket_fd;

static int hex(char ch)
{
   if ((ch >= 'a') && (ch <= 'f')) return(ch - 'a' + 10);
   if ((ch >= '0') && (ch <= '9')) return(ch - '0');
   if ((ch >= 'A') && (ch <= 'F')) return(ch - 'A' + 10);
   return(-1);
}

static void put_debug_char(char ch)
{
  send(socket_fd, &ch, 1, 0);
}

static char get_debug_char(void)
{
   char ch;
   
   recv(socket_fd, &ch, 1, 0);
   
   return(ch);
}

static const char hexchars[]="0123456789abcdef";

static void put_reply(char* buffer)
{
   unsigned char csum;
   int i;
   
   BX_DEBUG (("put_buffer %s", buffer));
   
   do { 
       put_debug_char('$');
       
       csum = 0;
       
       i = 0;
       while (buffer[i] != 0)
       {
            put_debug_char(buffer[i]);
            csum = csum + buffer[i];
            i++;
       }
       
       put_debug_char('#');
       put_debug_char(hexchars[csum >> 4]);
       put_debug_char(hexchars[csum % 16]);
   } while (get_debug_char() != '+');
}

static void get_command(char* buffer)
{
   unsigned char checksum;
   unsigned char xmitcsum;
   char ch;
   unsigned int count;
   unsigned int i;
   
   do{
       while ((ch = get_debug_char()) != '$');
       
       checksum = 0;
       xmitcsum = 0;
       count = 0;
   
       while (1)
       {
            ch = get_debug_char();
            if (ch == '#') break;
            checksum = checksum + ch;
            buffer[count] = ch;
            count++;
       }
       buffer[count] = 0;
       
       if (ch == '#')
       {
            xmitcsum = hex(get_debug_char()) << 4;
            xmitcsum += hex(get_debug_char());
            if (checksum != xmitcsum)
            {
                 BX_INFO(("Bad checksum"));
            }
       }
       
       if (checksum != xmitcsum)
       {
            put_debug_char('-');
       }
       else
       {
            put_debug_char('+');
            if (buffer[2] == ':')
            {
                 put_debug_char(buffer[0]);
                 put_debug_char(buffer[1]);
                 count = strlen(buffer);
                 for (i = 3; i <= count; i++)
                 {
                      buffer[i - 3] = buffer[i];
                 }
            }
       }
   } while (checksum != xmitcsum);   
}

void hex2mem(char* buf, unsigned char* mem, int count)
{
   int i;
   unsigned char ch;
   
   for (i = 0; i<count; i++)
   {
       ch = hex(*buf++) << 4;
       ch = ch + hex(*buf++);
       *mem = ch;
       mem++;
   }
}

char* mem2hex(char* mem, char* buf, int count)
{
   int i;
   unsigned char ch;
   
   for (i = 0; i<count; i++)
   {
       ch = *mem;
       mem++;
       *buf = hexchars[ch >> 4];
       buf++;
       *buf = hexchars[ch % 16];
       buf++;  
   }
   *buf = 0;
   return(buf);
}

int hexdigit(char c)
{
  if (isdigit(c))
    return c - '0';
  else if (isupper(c))
    return c - 'A' + 10;
  else
    return c - 'a' + 10;
}

Bit64u read_little_endian_hex(char *&buf)
{
  int byte;
  Bit64u ret = 0;
  int n = 0;
  while (isxdigit(*buf)) {
    byte = hexdigit(*buf++);
    if (isxdigit(*buf))
      byte = (byte << 4) | hexdigit(*buf++);
    ret |= (unsigned long long)byte << (n*8);
    ++n;
  }
  return ret;
}

static int continue_thread = -1;
static int other_thread = 0;

#if !BX_SUPPORT_X86_64
#define NUMREGS (16)
#define NUMREGSBYTES (NUMREGS * 4)
static int registers[NUMREGS];
#endif

#define MAX_BREAKPOINTS (255)
static unsigned int breakpoints[MAX_BREAKPOINTS] = {0,};
static unsigned int nr_breakpoints = 0;

static int stub_trace_flag = 0;
static int instr_count = 0;
static int saved_eip = 0;

int bx_gdbstub_check(unsigned int eip)
{
   unsigned int i;
   unsigned char ch;
   long arg;
   int r;
#if defined(__CYGWIN__) || defined(__MINGW32__)
   fd_set fds;
   struct timeval tv = {0, 0};
#endif

   instr_count++;
   
   if ((instr_count % 500) == 0)
   {
#if !defined(__CYGWIN__) && !defined(__MINGW32__)
       arg = fcntl(socket_fd, F_GETFL);
       fcntl(socket_fd, F_SETFL, arg | O_NONBLOCK);
       r = recv(socket_fd, &ch, 1, 0);
       fcntl(socket_fd, F_SETFL, arg);
#else
       FD_ZERO(&fds);
       FD_SET(socket_fd, &fds);
       r = select(socket_fd + 1, &fds, NULL, NULL, &tv);
       if (r == 1)
       {
           r = recv(socket_fd, (char *)&ch, 1, 0);
       }
#endif   
       if (r == 1)
       {
            BX_INFO(("Got byte %x", (unsigned int)ch));
            last_stop_reason = GDBSTUB_USER_BREAK;
            return(GDBSTUB_USER_BREAK);
       }
   }
   
   // why is trace before breakpoints? does that mean it would never
   // hit a breakpoint during tracing?
   if (stub_trace_flag == 1)
   {
       last_stop_reason = GDBSTUB_TRACE;
       return(GDBSTUB_TRACE);
   }
   for (i = 0; i < nr_breakpoints; i++)
   {
       if (eip == breakpoints[i])
       {
            BX_INFO(("found breakpoint at %x", eip));
            last_stop_reason = GDBSTUB_EXECUTION_BREAKPOINT;
            return(GDBSTUB_EXECUTION_BREAKPOINT);
       }
   }
   last_stop_reason = GDBSTUB_STOP_NO_REASON;
   return(GDBSTUB_STOP_NO_REASON);
}

static int remove_breakpoint(unsigned int addr, int len)
{
   unsigned int i;
   
   if (len != 1)
   {
       return(0);
   }
   
   for (i = 0; i < MAX_BREAKPOINTS; i++)
   {
       if (breakpoints[i] == addr)
       {
            BX_INFO(("Removing breakpoint at %x", addr));
            breakpoints[i] = 0;
            return(1);
       }
   }
   return(0);
}

static void insert_breakpoint(unsigned int addr)
{
   unsigned int i;
   
   BX_INFO(("setting breakpoint at %x", addr));
   
   for (i = 0; i < (unsigned)MAX_BREAKPOINTS; i++)
   {
       if (breakpoints[i] == 0)
       {
            breakpoints[i] = addr;
            if (i >= nr_breakpoints)
            {
                 nr_breakpoints = i + 1;
            }
            return;
       }
   }
   BX_INFO(("No slot for breakpoint"));
}

static void do_pc_breakpoint(int insert, unsigned long long addr, int len)
{
  for (int i = 0; i < len; ++i)
    if (insert)
      insert_breakpoint(addr+i);
    else
      remove_breakpoint(addr+i, 1);
}

static void do_breakpoint(int insert, char* buffer)
{
  char* ebuf;
  unsigned long type = strtoul(buffer, &ebuf, 16);
  unsigned long long addr = strtoull(ebuf+1, &ebuf, 16);
  unsigned long len = strtoul(ebuf+1, &ebuf, 16);
  switch (type) {
  case 0:
  case 1:
    do_pc_breakpoint(insert, addr, len);
    put_reply("OK");
    break;
  default:
    put_reply("");
    break;
  }
}

static void write_signal(char* buf, int signal)
{
   buf[0] = hexchars[signal >> 4];
   buf[1] = hexchars[signal % 16];
   buf[2] = 0;
}

static int access_linear(Bit64u laddress,
                        unsigned len,
                        unsigned int rw,
                        Bit8u* data)
{
   bx_phy_address phys;
   bx_bool valid;
    
   if (((laddress & 0xfff) + len) > 4096)
   {
       valid = access_linear(laddress,
                             4096 - (laddress & 0xfff),
                             rw,
                             data);
       if (!valid) return(0);

       valid = access_linear(laddress,
                             len + (laddress & 0xfff) - 4096,
                             rw,
                             (Bit8u *)((unsigned long)data + 
                                      4096 - (laddress & 0xfff)));
       return(valid);
   }
   
   valid = BX_CPU(0)->dbg_xlate_linear2phy(laddress, (bx_phy_address*)&phys);
   if (!valid) return(0);
   
   if (rw == BX_READ) {
       valid = BX_MEM(0)->dbg_fetch_mem(BX_CPU(0), phys, len, data);
   }
   else {
       valid = BX_MEM(0)->dbg_set_mem(phys, len, data);
   }

   return(valid);
}

static void debug_loop(void)
{
   char buffer[255];
   char obuf[255];
   int ne;
   unsigned char mem[255];
   
   ne = 0;
   
   while (ne == 0)
   {
       get_command(buffer);
       BX_DEBUG (("get_buffer %s", buffer));
       
       switch (buffer[0])
       {
          case 'c':
              {
                 char buf[255];
                 int new_eip;
                 
                 if (buffer[1] != 0)
                 {
                      new_eip = atoi(buffer + 1);
                      
                      BX_INFO(("continuing at %x", new_eip));
                      
		      for (int i=0; i<BX_SMP_PROCESSORS; i++) {
                        BX_CPU(i)->invalidate_prefetch_q();
		      }
                      
                      saved_eip = EIP;
                      
                      BX_CPU(0)->dword.eip = new_eip;
                 }
                 
                 stub_trace_flag = 0;
                 bx_cpu.ispanic = 0;
                 bx_cpu.cpu_loop(0);              
                 if (bx_cpu.ispanic)
                 {
                    last_stop_reason = GDBSTUB_EXECUTION_BREAKPOINT;
                 }

                 DEV_vga_refresh();
                 
                 if (buffer[1] != 0)
                 {
                      bx_cpu.invalidate_prefetch_q();
                      BX_CPU_THIS_PTR dword.eip = saved_eip;
                 }
                 
                 BX_INFO(("stopped with %x", last_stop_reason));                               
                 buf[0] = 'S';
                 if (last_stop_reason == GDBSTUB_EXECUTION_BREAKPOINT ||
                     last_stop_reason == GDBSTUB_TRACE)
                 {
                      write_signal(&buf[1], SIGTRAP);
                 }
                 else
                 {
                      write_signal(&buf[1], 0);
                 }
                 put_reply(buf);
                 break;
              }
            
          case 's':
              {
                 char buf[255];
                 
                 BX_INFO(("stepping"));
                 stub_trace_flag = 1;
                 bx_cpu.cpu_loop(0);
                 DEV_vga_refresh();
                 stub_trace_flag = 0;
                 BX_INFO(("stopped with %x", last_stop_reason));
                 buf[0] = 'S';
                 if (last_stop_reason == GDBSTUB_EXECUTION_BREAKPOINT ||
                     last_stop_reason == GDBSTUB_TRACE)
                 {
                      write_signal(&buf[1], SIGTRAP);
                 }
                 else
                 {
                      write_signal(&buf[1], SIGTRAP);
                 }
                 put_reply(buf);
                 break;
              }
            
          case 'M':
              {
                 Bit64u addr;
                 int len;
                 unsigned char mem[255];
                 char* ebuf;
                 
                 addr = strtoull(&buffer[1], &ebuf, 16);
                 len = strtoul(ebuf + 1, &ebuf, 16);
                 hex2mem(ebuf + 1, mem, len);          
                 
                 if (len == 1 && mem[0] == 0xcc)
                 {
                      insert_breakpoint(addr);
                      put_reply("OK");
                 }
                 else if (remove_breakpoint(addr, len))
                 {
                      put_reply("OK");
                 }
                 else
                 {
                      if (access_linear(addr,
                                        len,
                                        BX_WRITE,
                                        mem))
                      {
                           put_reply("OK");
                      }
                      else
                      {
                           put_reply("ENN");
                      }
                 }
                 break;                    
              }
            
          case 'm':
              {
                 Bit64u addr;
                 int len;
                 char* ebuf;
                 
                 addr = strtoull(&buffer[1], &ebuf, 16);
                 len = strtoul(ebuf + 1, NULL, 16);
                 BX_INFO(("addr %x len %x", addr, len));
                 
                 access_linear(addr,
                               len,
                               BX_READ,
                               mem);
                 mem2hex((char *)mem, obuf, len);
                 put_reply(obuf);
                 break;
              }
          case 'P':
              {
                 int reg;
                 unsigned long long value;
                 char* ebuf;
                 
                 reg = strtoul(&buffer[1], &ebuf, 16);
		 ++ebuf;
                 value = read_little_endian_hex(ebuf);
                 
                 BX_INFO(("reg %d set to %llx", reg, value));
#if !BX_SUPPORT_X86_64                 
                 switch (reg)
                 {
                    case 1:
                      EAX = value;
                      break;
                      
                    case 2:
                      ECX = value;
                      break;
                      
                    case 3:
                      EBX = value;
                      break;
                      
                    case 4:
                      ESP = value;
                      break;
                      
                    case 5:
                      EBP = value;
                      break;
                      
                    case 6:
                      ESI = value;
                      break;
                      
                    case 7:
                      EDI = value;
                      break;
                      
                    case 8:
                      EIP = value;
                      BX_CPU_THIS_PTR invalidate_prefetch_q();
                      break;
                      
                    default:
                      break;
                 }
#else
                 switch (reg)
                 {
                    case 0:
                      RAX = value;
                      break;
                      
                    case 1:
                      RBX = value;
                      break;
                      
                    case 2:
                      RCX = value;
                      break;
                      
                    case 3:
                      RDX = value;
                      break;
                      
                    case 4:
                      RSI = value;
                      break;
                      
                    case 5:
                      RDI = value;
                      break;
                      
                    case 6:
                      ESP = value;
                      break;
                      
                    case 7:
		      RBP = value;
		      break;

                    case 8:
		      R8 = value;
		      break;

                    case 9:
		      R9 = value;
		      break;

                    case 10:
		      R10 = value;
		      break;

                    case 11:
		      R11 = value;
		      break;

                    case 12:
		      R12 = value;
		      break;

                    case 13:
		      R13 = value;
		      break;

                    case 14:
		      R15 = value;
		      break;

                    case 15:
		      R15 = value;
		      break;

		    case 16:
                      RIP = value;
                      BX_CPU_THIS_PTR invalidate_prefetch_q();
                      break;
                      
                    default:
                      break;
                 }
#endif                 
                 put_reply("OK");
                 
                 break;
              }
            
          case 'g':
#if !BX_SUPPORT_X86_64
            registers[0] = EAX;
            registers[1] = ECX;
            registers[2] = EDX;
            registers[3] = EBX;
            registers[4] = ESP;
            registers[5] = EBP;
            registers[6] = ESI;
            registers[7] = EDI;
            if (last_stop_reason == GDBSTUB_EXECUTION_BREAKPOINT)
            {
                 registers[8] = EIP + 1;
            }
            else
            {
                 registers[8] = EIP;
            }
            registers[9] = BX_CPU_THIS_PTR read_eflags();
            registers[10] = 
              BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value;
            registers[11] = 
              BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].selector.value;
            registers[12] = 
              BX_CPU_THIS_PTR sregs[BX_SEG_REG_DS].selector.value;
            registers[13] = 
              BX_CPU_THIS_PTR sregs[BX_SEG_REG_ES].selector.value;
            registers[14] = 
              BX_CPU_THIS_PTR sregs[BX_SEG_REG_FS].selector.value;
            registers[15] = 
              BX_CPU_THIS_PTR sregs[BX_SEG_REG_GS].selector.value;
            mem2hex((char *)registers, obuf, NUMREGSBYTES);
#else
#define PUTREG(buf, val, len) do { \
         Bit64u u = (val); \
         (buf) = mem2hex((char*)&u, (buf), (len)); \
      } while (0)
            char* buf;
	    buf = obuf;
            PUTREG(buf, RAX, 8);
            PUTREG(buf, RBX, 8);
            PUTREG(buf, RCX, 8);
            PUTREG(buf, RDX, 8);
            PUTREG(buf, RSI, 8);
            PUTREG(buf, RDI, 8);
            PUTREG(buf, RBP, 8);
            PUTREG(buf, RSP, 8);
            PUTREG(buf, R8,  8);
            PUTREG(buf, R9,  8);
            PUTREG(buf, R10, 8);
            PUTREG(buf, R11, 8);
            PUTREG(buf, R12, 8);
            PUTREG(buf, R13, 8);
            PUTREG(buf, R14, 8);
            PUTREG(buf, R15, 8);
	    Bit64u rip;
	    rip = RIP;
            if (last_stop_reason == GDBSTUB_EXECUTION_BREAKPOINT)
            {
		++rip;
            }
            PUTREG(buf, rip, 8);
	    PUTREG(buf, BX_CPU_THIS_PTR read_eflags(), 4);
            PUTREG(buf, BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value, 4);
            PUTREG(buf, BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].selector.value, 4);
            PUTREG(buf, BX_CPU_THIS_PTR sregs[BX_SEG_REG_DS].selector.value, 4);
            PUTREG(buf, BX_CPU_THIS_PTR sregs[BX_SEG_REG_ES].selector.value, 4);
            PUTREG(buf, BX_CPU_THIS_PTR sregs[BX_SEG_REG_FS].selector.value, 4);
            PUTREG(buf, BX_CPU_THIS_PTR sregs[BX_SEG_REG_GS].selector.value, 4);
#endif
            put_reply(obuf);
            break;
            
          case '?':
            sprintf(obuf, "S%02x", SIGTRAP);
            put_reply(obuf);
            break;
            
          case 'H':
            if (buffer[1] == 'c')
            {
                 continue_thread = strtol(&buffer[2], NULL, 16);
                 put_reply("OK");
            }
            else if (buffer[1] == 'g')
            {
                 other_thread = strtol(&buffer[2], NULL, 16);
                 put_reply("OK");
            }
            else
            {
                 put_reply("ENN");
            }
            break;
            
          case 'q':
            if (buffer[1] == 'C')
            {
                 sprintf(obuf,"%Lx", 1);
                 put_reply(obuf);
            }
            else if (strncmp(&buffer[1], "Offsets", strlen("Offsets")) == 0)
            {
                 sprintf(obuf,
                         "Text=%x;Data=%x;Bss=%x",
                         SIM->get_param_num("text_base", gdbstub_list)->get(),
                         SIM->get_param_num("data_base", gdbstub_list)->get(),
                         SIM->get_param_num("bss_base", gdbstub_list)->get());
                 put_reply(obuf);
            }
            else {
                 put_reply("ENN");
            }          
            break;

	  case 'Z':
	    do_breakpoint(1, buffer+1);
	    break;
	  case 'z':
	    do_breakpoint(0, buffer+1);
	    break;
          case 'k':
            BX_PANIC(("Debugger asked us to quit\n"));
            break;
            
          default:
            put_reply("");
            break;
       }
   }
}

static void wait_for_connect(int portn)
{
   struct sockaddr_in sockaddr;
   socklen_t sockaddr_len;
   struct protoent *protoent;
   int r;
   int opt;
   
   listen_socket_fd = socket(PF_INET, SOCK_STREAM, 0);
   if (listen_socket_fd == -1)
   {
       BX_PANIC(("Failed to create socket\n"));
       exit(1);
   }
   
   /* Allow rapid reuse of this port */
   opt = 1;
#if __MINGW32__
   r = setsockopt(listen_socket_fd, SOL_SOCKET, SO_REUSEADDR, (const char *)&opt, sizeof(opt));
#else
   r = setsockopt(listen_socket_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
#endif
   if (r == -1)
   {
       BX_INFO(("setsockopt(SO_REUSEADDR) failed\n"));
   }
   
   memset (&sockaddr, '\000', sizeof sockaddr);
#if BX_HAVE_SOCKADDR_IN_SIN_LEN
   // if you don't have sin_len change that to #if 0.  This is the subject of
   // bug [ 626840 ] no 'sin_len' in 'struct sockaddr_in'.
   sockaddr.sin_len = sizeof sockaddr;
#endif
   sockaddr.sin_family = AF_INET;
   sockaddr.sin_port = htons(portn);
   sockaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);

   r = bind(listen_socket_fd, (struct sockaddr *)&sockaddr, sizeof(sockaddr));
   if (r == -1)
   {
       BX_PANIC(("Failed to bind socket\n"));
   }

   r = listen(listen_socket_fd, 0);
   if (r == -1)
   {
       BX_PANIC(("Failed to listen on socket\n"));
   }
   
   sockaddr_len = sizeof sockaddr;
   socket_fd = accept(listen_socket_fd, (struct sockaddr *)&sockaddr, &sockaddr_len);
   if (socket_fd == -1)
   {
       BX_PANIC(("Failed to accept on socket\n"));
   }
   close(listen_socket_fd);
   
   protoent = getprotobyname ("tcp");
   if (!protoent)
   {
       BX_INFO(("getprotobyname (\"tcp\") failed\n"));
       return;
   }

   /* Disable Nagle - allow small packets to be sent without delay. */
   opt = 1;
#ifdef __MINGW32__
   r = setsockopt (socket_fd, protoent->p_proto, TCP_NODELAY, (const char *)&opt, sizeof(opt));
#else
   r = setsockopt (socket_fd, protoent->p_proto, TCP_NODELAY, &opt, sizeof(opt));
#endif
   if (r == -1)
   {
       BX_INFO(("setsockopt(TCP_NODELAY) failed\n"));
   }
}

void bx_gdbstub_init(int argc, char* argv[])
{
   gdbstub_list = (bx_list_c*) SIM->get_param(BXPN_GDBSTUB);
   int portn = SIM->get_param_num("port", gdbstub_list)->get();

#ifdef __MINGW32__
   WSADATA wsaData;
   WSAStartup(2, &wsaData);
#endif

   /* Wait for connect */
   printf("Waiting for gdb connection on localhost:%d\n", portn);
   wait_for_connect(portn);
   
   /* Do debugger command loop */
   debug_loop();

   /* CPU loop */
   bx_cpu.cpu_loop(0);
}