remote_gdb.cc

M5,一个功能强大的多处理器系统模拟器.很多针对处理器架构,性能的研究都使用它作为模拟平台

    return true;
}

PCEventQueue *BaseRemoteGDB::getPcEventQueue()
{
    return &system->pcEventQueue;
}

BaseRemoteGDB::HardBreakpoint::HardBreakpoint(BaseRemoteGDB *_gdb, Addr pc)
    : PCEvent(_gdb->getPcEventQueue(), "HardBreakpoint Event", pc),
      gdb(_gdb), refcount(0)
{
    DPRINTF(GDBMisc, "creating hardware breakpoint at %#x\n", evpc);
}

void
BaseRemoteGDB::HardBreakpoint::process(ThreadContext *tc)
{
    DPRINTF(GDBMisc, "handling hardware breakpoint at %#x\n", pc());

    if (tc == gdb->context)
        gdb->trap(SIGTRAP);
}

bool
BaseRemoteGDB::insertSoftBreak(Addr addr, size_t len)
{
    if (len != sizeof(TheISA::MachInst))
        panic("invalid length\n");

    return insertHardBreak(addr, len);
}

bool
BaseRemoteGDB::removeSoftBreak(Addr addr, size_t len)
{
    if (len != sizeof(MachInst))
        panic("invalid length\n");

    return removeHardBreak(addr, len);
}

bool
BaseRemoteGDB::insertHardBreak(Addr addr, size_t len)
{
    if (len != sizeof(MachInst))
        panic("invalid length\n");

    DPRINTF(GDBMisc, "inserting hardware breakpoint at %#x\n", addr);

    HardBreakpoint *&bkpt = hardBreakMap[addr];
    if (bkpt == 0)
        bkpt = new HardBreakpoint(this, addr);

    bkpt->refcount++;

    return true;
}

bool
BaseRemoteGDB::removeHardBreak(Addr addr, size_t len)
{
    if (len != sizeof(MachInst))
        panic("invalid length\n");

    DPRINTF(GDBMisc, "removing hardware breakpoint at %#x\n", addr);

    break_iter_t i = hardBreakMap.find(addr);
    if (i == hardBreakMap.end())
        return false;

    HardBreakpoint *hbp = (*i).second;
    if (--hbp->refcount == 0) {
        delete hbp;
        hardBreakMap.erase(i);
    }

    return true;
}

void
BaseRemoteGDB::setTempBreakpoint(Addr bkpt)
{
    DPRINTF(GDBMisc, "setTempBreakpoint: addr=%#x\n", bkpt);
    insertHardBreak(bkpt, sizeof(TheISA::MachInst));
}

void
BaseRemoteGDB::clearTempBreakpoint(Addr &bkpt)
{
    DPRINTF(GDBMisc, "setTempBreakpoint: addr=%#x\n", bkpt);
    removeHardBreak(bkpt, sizeof(TheISA::MachInst));
    bkpt = 0;
}

const char *
BaseRemoteGDB::break_type(char c)
{
    switch(c) {
      case '0': return "software breakpoint";
      case '1': return "hardware breakpoint";
      case '2': return "write watchpoint";
      case '3': return "read watchpoint";
      case '4': return "access watchpoint";
      default: return "unknown breakpoint/watchpoint";
    }
}

// This function does all command processing for interfacing to a
// remote gdb.  Note that the error codes are ignored by gdb at
// present, but might eventually become meaningful. (XXX) It might
// makes sense to use POSIX errno values, because that is what the
// gdb/remote.c functions want to return.
bool
BaseRemoteGDB::trap(int type)
{
    uint64_t val;
    size_t datalen, len;
    char data[GDBPacketBufLen + 1];
    char *buffer;
    int bufferSize;
    const char *p;
    char command, subcmd;
    string var;
    bool ret;

    if (!attached)
        return false;

    bufferSize = gdbregs.bytes() * 2 + 256;
    buffer = (char*)malloc(bufferSize);

    DPRINTF(GDBMisc, "trap: PC=%#x NPC=%#x\n",
            context->readPC(), context->readNextPC());

    clearSingleStep();

    /*
     * The first entry to this function is normally through
     * a breakpoint trap in kgdb_connect(), in which case we
     * must advance past the breakpoint because gdb will not.
     *
     * On the first entry here, we expect that gdb is not yet
     * listening to us, so just enter the interaction loop.
     * After the debugger is "active" (connected) it will be
     * waiting for a "signaled" message from us.
     */
    if (!active)
        active = true;
    else
        // Tell remote host that an exception has occurred.
        snprintf((char *)buffer, bufferSize, "S%02x", type);
        send(buffer);

    // Stick frame regs into our reg cache.
    getregs();

    for (;;) {
        datalen = recv(data, sizeof(data));
        data[sizeof(data) - 1] = 0; // Sentinel
        command = data[0];
        subcmd = 0;
        p = data + 1;
        switch (command) {

          case GDBSignal:
            // if this command came from a running gdb, answer it --
            // the other guy has no way of knowing if we're in or out
            // of this loop when he issues a "remote-signal".
            snprintf((char *)buffer, bufferSize,
                    "S%02x", type);
            send(buffer);
            continue;

          case GDBRegR:
            if (2 * gdbregs.bytes() > bufferSize)
                panic("buffer too small");

            mem2hex(buffer, gdbregs.regs, gdbregs.bytes());
            send(buffer);
            continue;

          case GDBRegW:
            p = hex2mem(gdbregs.regs, p, gdbregs.bytes());
            if (p == NULL || *p != '\0')
                send("E01");
            else {
                setregs();
                send("OK");
            }
            continue;

#if 0
          case GDBSetReg:
            val = hex2i(&p);
            if (*p++ != '=') {
                send("E01");
                continue;
            }
            if (val < 0 && val >= KGDB_NUMREGS) {
                send("E01");
                continue;
            }

            gdbregs.regs[val] = hex2i(&p);
            setregs();
            send("OK");

            continue;
#endif

          case GDBMemR:
            val = hex2i(&p);
            if (*p++ != ',') {
                send("E02");
                continue;
            }
            len = hex2i(&p);
            if (*p != '\0') {
                send("E03");
                continue;
            }
            if (len > bufferSize) {
                send("E04");
                continue;
            }
            if (!acc(val, len)) {
                send("E05");
                continue;
            }

            if (read(val, (size_t)len, (char *)buffer)) {
               // variable length array would be nice, but C++ doesn't
               // officially support those...
               char *temp = new char[2*len+1];
               mem2hex(temp, buffer, len);
               send(temp);
               delete [] temp;
            } else {
               send("E05");
            }
            continue;

          case GDBMemW:
            val = hex2i(&p);
            if (*p++ != ',') {
                send("E06");
                continue;
            }
            len = hex2i(&p);
            if (*p++ != ':') {
                send("E07");
                continue;
            }
            if (len > datalen - (p - data)) {
                send("E08");
                continue;
            }
            p = hex2mem(buffer, p, bufferSize);
            if (p == NULL) {
                send("E09");
                continue;
            }
            if (!acc(val, len)) {
                send("E0A");
                continue;
            }
            if (write(val, (size_t)len, (char *)buffer))
              send("OK");
            else
              send("E0B");
            continue;

          case GDBSetThread:
            subcmd = *p++;
            val = hex2i(&p);
            if (val == 0)
                send("OK");
            else
                send("E01");
            continue;

          case GDBDetach:
          case GDBKill:
            active = false;
            clearSingleStep();
            detach();
            goto out;

          case GDBAsyncCont:
            subcmd = hex2i(&p);
            if (*p++ == ';') {
                val = hex2i(&p);
                context->setPC(val);
                context->setNextPC(val + sizeof(MachInst));
            }
            clearSingleStep();
            goto out;

          case GDBCont:
            if (p - data < datalen) {
                val = hex2i(&p);
                context->setPC(val);
                context->setNextPC(val + sizeof(MachInst));
            }
            clearSingleStep();
            goto out;

          case GDBAsyncStep:
            subcmd = hex2i(&p);
            if (*p++ == ';') {
                val = hex2i(&p);
                context->setPC(val);
                context->setNextPC(val + sizeof(MachInst));
            }
            setSingleStep();
            goto out;

          case GDBStep:
            if (p - data < datalen) {
                val = hex2i(&p);
                context->setPC(val);
                context->setNextPC(val + sizeof(MachInst));
            }
            setSingleStep();
            goto out;

          case GDBClrHwBkpt:
            subcmd = *p++;
            if (*p++ != ',') send("E0D");
            val = hex2i(&p);
            if (*p++ != ',') send("E0D");
            len = hex2i(&p);

            DPRINTF(GDBMisc, "clear %s, addr=%#x, len=%d\n",
                    break_type(subcmd), val, len);

            ret = false;

            switch (subcmd) {
              case '0': // software breakpoint
                ret = removeSoftBreak(val, len);
                break;

              case '1': // hardware breakpoint
                ret = removeHardBreak(val, len);
                break;

              case '2': // write watchpoint
              case '3': // read watchpoint
              case '4': // access watchpoint
              default: // unknown
                send("");
                break;
            }

            send(ret ? "OK" : "E0C");
            continue;

          case GDBSetHwBkpt:
            subcmd = *p++;
            if (*p++ != ',') send("E0D");
            val = hex2i(&p);
            if (*p++ != ',') send("E0D");
            len = hex2i(&p);

            DPRINTF(GDBMisc, "set %s, addr=%#x, len=%d\n",
                    break_type(subcmd), val, len);

            ret = false;

            switch (subcmd) {
              case '0': // software breakpoint
                ret = insertSoftBreak(val, len);
                break;

              case '1': // hardware breakpoint
                ret = insertHardBreak(val, len);
                break;

              case '2': // write watchpoint
              case '3': // read watchpoint
              case '4': // access watchpoint
              default: // unknown
                send("");
                break;
            }

            send(ret ? "OK" : "E0C");
            continue;

          case GDBQueryVar:
            var = string(p, datalen - 1);
            if (var == "C")
                send("QC0");
            else
                send("");
            continue;

          case GDBSetBaud:
          case GDBSetBreak:
          case GDBDebug:
          case GDBCycleStep:
          case GDBSigCycleStep:
          case GDBReadReg:
          case GDBSetVar:
          case GDBReset:
          case GDBThreadAlive:
          case GDBTargetExit:
          case GDBBinaryDload:
            // Unsupported command
            DPRINTF(GDBMisc, "Unsupported command: %s\n",
                    gdb_command(command));
            DDUMP(GDBMisc, (uint8_t *)data, datalen);
            send("");
            continue;

          default:
            // Unknown command.
            DPRINTF(GDBMisc, "Unknown command: %c(%#x)\n",
                    command, command);
            send("");
            continue;


        }
    }

  out:
    free(buffer);
    return true;
}

// Convert a hex digit into an integer.
// This returns -1 if the argument passed is no valid hex digit.
int
BaseRemoteGDB::digit2i(char c)
{
    if (c >= '0' && c <= '9')
        return (c - '0');
    else if (c >= 'a' && c <= 'f')
        return (c - 'a' + 10);
    else if (c >= 'A' && c <= 'F')

        return (c - 'A' + 10);
    else
        return (-1);
}

// Convert the low 4 bits of an integer into an hex digit.
char
BaseRemoteGDB::i2digit(int n)
{
    return ("0123456789abcdef"[n & 0x0f]);
}

// Convert a byte array into an hex string.
void
BaseRemoteGDB::mem2hex(void *vdst, const void *vsrc, int len)
{
    char *dst = (char *)vdst;
    const char *src = (const char *)vsrc;

    while (len--) {
        *dst++ = i2digit(*src >> 4);
        *dst++ = i2digit(*src++);
    }
    *dst = '\0';
}

// Convert an hex string into a byte array.
// This returns a pointer to the character following the last valid
// hex digit. If the string ends in the middle of a byte, NULL is
// returned.
const char *
BaseRemoteGDB::hex2mem(void *vdst, const char *src, int maxlen)
{
    char *dst = (char *)vdst;
    int msb, lsb;

    while (*src && maxlen--) {
        msb = digit2i(*src++);
        if (msb < 0)
            return (src - 1);
        lsb = digit2i(*src++);
        if (lsb < 0)
            return (NULL);
        *dst++ = (msb << 4) | lsb;
    }
    return (src);
}

// Convert an hex string into an integer.
// This returns a pointer to the character following the last valid
// hex digit.
Addr
BaseRemoteGDB::hex2i(const char **srcp)
{
    const char *src = *srcp;
    Addr r = 0;
    int nibble;

    while ((nibble = digit2i(*src)) >= 0) {
        r *= 16;
        r += nibble;
        src++;
    }
    *srcp = src;
    return (r);
}