gdbstub.c

qemu性能直逼VMware的仿真器QEMU 的模擬速度約為實機的 25％；約為 Bochs 的 60 倍。Plex86、User-Mode-Linux、VMware 和 Virtual PC 則比

        if (*p == ':')
            p++;
        hextomem(mem_buf, p, len);
        if (cpu_memory_rw_debug(env, addr, mem_buf, len, 1) != 0)
            put_packet(s, "E14");
        else
            put_packet(s, "OK");
        break;
    case 'Z':
        type = strtoul(p, (char **)&p, 16);
        if (*p == ',')
            p++;
        addr = strtoull(p, (char **)&p, 16);
        if (*p == ',')
            p++;
        len = strtoull(p, (char **)&p, 16);
        if (type == 0 || type == 1) {
            if (cpu_breakpoint_insert(env, addr) < 0)
                goto breakpoint_error;
            put_packet(s, "OK");
        } else {
        breakpoint_error:
            put_packet(s, "E22");
        }
        break;
    case 'z':
        type = strtoul(p, (char **)&p, 16);
        if (*p == ',')
            p++;
        addr = strtoull(p, (char **)&p, 16);
        if (*p == ',')
            p++;
        len = strtoull(p, (char **)&p, 16);
        if (type == 0 || type == 1) {
            cpu_breakpoint_remove(env, addr);
            put_packet(s, "OK");
        } else {
            goto breakpoint_error;
        }
        break;
#ifdef CONFIG_LINUX_USER
    case 'q':
        if (strncmp(p, "Offsets", 7) == 0) {
            TaskState *ts = env->opaque;

            sprintf(buf, "Text=%x;Data=%x;Bss=%x", ts->info->code_offset,
                ts->info->data_offset, ts->info->data_offset);
            put_packet(s, buf);
            break;
        }
        /* Fall through.  */
#endif
    default:
        //        unknown_command:
        /* put empty packet */
        buf[0] = '\0';
        put_packet(s, buf);
        break;
    }
    return RS_IDLE;
}

extern void tb_flush(CPUState *env);

#ifndef CONFIG_USER_ONLY
static void gdb_vm_stopped(void *opaque, int reason)
{
    GDBState *s = opaque;
    char buf[256];
    int ret;

    if (s->state == RS_SYSCALL)
        return;

    /* disable single step if it was enable */
    cpu_single_step(s->env, 0);

    if (reason == EXCP_DEBUG) {
	tb_flush(s->env);
        ret = SIGTRAP;
    } else if (reason == EXCP_INTERRUPT) {
        ret = SIGINT;
    } else {
        ret = 0;
    }
    snprintf(buf, sizeof(buf), "S%02x", ret);
    put_packet(s, buf);
}
#endif

/* Send a gdb syscall request.
   This accepts limited printf-style format specifiers, specifically:
    %x - target_ulong argument printed in hex.
    %s - string pointer (target_ulong) and length (int) pair.  */
void gdb_do_syscall(gdb_syscall_complete_cb cb, char *fmt, ...)
{
    va_list va;
    char buf[256];
    char *p;
    target_ulong addr;
    GDBState *s;

    s = gdb_syscall_state;
    if (!s)
        return;
    gdb_current_syscall_cb = cb;
    s->state = RS_SYSCALL;
#ifndef CONFIG_USER_ONLY
    vm_stop(EXCP_DEBUG);
#endif
    s->state = RS_IDLE;
    va_start(va, fmt);
    p = buf;
    *(p++) = 'F';
    while (*fmt) {
        if (*fmt == '%') {
            fmt++;
            switch (*fmt++) {
            case 'x':
                addr = va_arg(va, target_ulong);
                p += sprintf(p, TARGET_FMT_lx, addr);
                break;
            case 's':
                addr = va_arg(va, target_ulong);
                p += sprintf(p, TARGET_FMT_lx "/%x", addr, va_arg(va, int));
                break;
            default:
                fprintf(stderr, "gdbstub: Bad syscall format string '%s'\n",
                        fmt - 1);
                break;
            }
        } else {
            *(p++) = *(fmt++);
        }
    }
    va_end(va);
    put_packet(s, buf);
#ifdef CONFIG_USER_ONLY
    gdb_handlesig(s->env, 0);
#else
    cpu_interrupt(s->env, CPU_INTERRUPT_EXIT);
#endif
}

static void gdb_read_byte(GDBState *s, int ch)
{
    CPUState *env = s->env;
    int i, csum;
    char reply[1];

#ifndef CONFIG_USER_ONLY
    if (s->last_packet_len) {
        /* Waiting for a response to the last packet.  If we see the start
           of a new command then abandon the previous response.  */
        if (ch == '-') {
#ifdef DEBUG_GDB
            printf("Got NACK, retransmitting\n");
#endif
            put_buffer(s, s->last_packet, s->last_packet_len);
        }
#ifdef DEBUG_GDB
        else if (ch == '+')
            printf("Got ACK\n");
        else
            printf("Got '%c' when expecting ACK/NACK\n", ch);
#endif
        if (ch == '+' || ch == '$')
            s->last_packet_len = 0;
        if (ch != '$')
            return;
    }
    if (vm_running) {
        /* when the CPU is running, we cannot do anything except stop
           it when receiving a char */
        vm_stop(EXCP_INTERRUPT);
    } else 
#endif
    {
        switch(s->state) {
        case RS_IDLE:
            if (ch == '$') {
                s->line_buf_index = 0;
                s->state = RS_GETLINE;
            }
            break;
        case RS_GETLINE:
            if (ch == '#') {
            s->state = RS_CHKSUM1;
            } else if (s->line_buf_index >= sizeof(s->line_buf) - 1) {
                s->state = RS_IDLE;
            } else {
            s->line_buf[s->line_buf_index++] = ch;
            }
            break;
        case RS_CHKSUM1:
            s->line_buf[s->line_buf_index] = '\0';
            s->line_csum = fromhex(ch) << 4;
            s->state = RS_CHKSUM2;
            break;
        case RS_CHKSUM2:
            s->line_csum |= fromhex(ch);
            csum = 0;
            for(i = 0; i < s->line_buf_index; i++) {
                csum += s->line_buf[i];
            }
            if (s->line_csum != (csum & 0xff)) {
                reply[0] = '-';
                put_buffer(s, reply, 1);
                s->state = RS_IDLE;
            } else {
                reply[0] = '+';
                put_buffer(s, reply, 1);
                s->state = gdb_handle_packet(s, env, s->line_buf);
            }
            break;
        default:
            abort();
        }
    }
}

#ifdef CONFIG_USER_ONLY
int
gdb_handlesig (CPUState *env, int sig)
{
  GDBState *s;
  char buf[256];
  int n;

  if (gdbserver_fd < 0)
    return sig;

  s = &gdbserver_state;

  /* disable single step if it was enabled */
  cpu_single_step(env, 0);
  tb_flush(env);

  if (sig != 0)
    {
      snprintf(buf, sizeof(buf), "S%02x", sig);
      put_packet(s, buf);
    }

  sig = 0;
  s->state = RS_IDLE;
  s->running_state = 0;
  while (s->running_state == 0) {
      n = read (s->fd, buf, 256);
      if (n > 0)
        {
          int i;

          for (i = 0; i < n; i++)
            gdb_read_byte (s, buf[i]);
        }
      else if (n == 0 || errno != EAGAIN)
        {
          /* XXX: Connection closed.  Should probably wait for annother
             connection before continuing.  */
          return sig;
        }
  }
  return sig;
}

/* Tell the remote gdb that the process has exited.  */
void gdb_exit(CPUState *env, int code)
{
  GDBState *s;
  char buf[4];

  if (gdbserver_fd < 0)
    return;

  s = &gdbserver_state;

  snprintf(buf, sizeof(buf), "W%02x", code);
  put_packet(s, buf);
}


static void gdb_accept(void *opaque)
{
    GDBState *s;
    struct sockaddr_in sockaddr;
    socklen_t len;
    int val, fd;

    for(;;) {
        len = sizeof(sockaddr);
        fd = accept(gdbserver_fd, (struct sockaddr *)&sockaddr, &len);
        if (fd < 0 && errno != EINTR) {
            perror("accept");
            return;
        } else if (fd >= 0) {
            break;
        }
    }

    /* set short latency */
    val = 1;
    setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, (char *)&val, sizeof(val));
    
    s = &gdbserver_state;
    memset (s, 0, sizeof (GDBState));
    s->env = first_cpu; /* XXX: allow to change CPU */
    s->fd = fd;

    gdb_syscall_state = s;

    fcntl(fd, F_SETFL, O_NONBLOCK);
}

static int gdbserver_open(int port)
{
    struct sockaddr_in sockaddr;
    int fd, val, ret;

    fd = socket(PF_INET, SOCK_STREAM, 0);
    if (fd < 0) {
        perror("socket");
        return -1;
    }

    /* allow fast reuse */
    val = 1;
    setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (char *)&val, sizeof(val));

    sockaddr.sin_family = AF_INET;
    sockaddr.sin_port = htons(port);
    sockaddr.sin_addr.s_addr = 0;
    ret = bind(fd, (struct sockaddr *)&sockaddr, sizeof(sockaddr));
    if (ret < 0) {
        perror("bind");
        return -1;
    }
    ret = listen(fd, 0);
    if (ret < 0) {
        perror("listen");
        return -1;
    }
    return fd;
}

int gdbserver_start(int port)
{
    gdbserver_fd = gdbserver_open(port);
    if (gdbserver_fd < 0)
        return -1;
    /* accept connections */
    gdb_accept (NULL);
    return 0;
}
#else
static int gdb_chr_can_recieve(void *opaque)
{
  return 1;
}

static void gdb_chr_recieve(void *opaque, const uint8_t *buf, int size)
{
    GDBState *s = opaque;
    int i;

    for (i = 0; i < size; i++) {
        gdb_read_byte(s, buf[i]);
    }
}

static void gdb_chr_event(void *opaque, int event)
{
    switch (event) {
    case CHR_EVENT_RESET:
        vm_stop(EXCP_INTERRUPT);
        gdb_syscall_state = opaque;
        break;
    default:
        break;
    }
}

int gdbserver_start(CharDriverState *chr)
{
    GDBState *s;

    if (!chr)
        return -1;

    s = qemu_mallocz(sizeof(GDBState));
    if (!s) {
        return -1;
    }
    s->env = first_cpu; /* XXX: allow to change CPU */
    s->chr = chr;
    qemu_chr_add_handlers(chr, gdb_chr_can_recieve, gdb_chr_recieve,
                          gdb_chr_event, s);
    qemu_add_vm_stop_handler(gdb_vm_stopped, s);
    return 0;
}

int gdbserver_start_port(int port)
{
    CharDriverState *chr;
    char gdbstub_port_name[128];

    snprintf(gdbstub_port_name, sizeof(gdbstub_port_name),
             "tcp::%d,nowait,nodelay,server", port);
    chr = qemu_chr_open(gdbstub_port_name);
    if (!chr) 
        return -EIO;
    return gdbserver_start(chr);
}

#endif