d4eca120ac
Summary: This packet is necessary to make lldb work with the remote-gdb stub in user mode qemu when running position-independent binaries. It reports the relative position (load bias) of the loaded executable wrt. the addresses in the file itself. Lldb needs to know this information in order to correctly set the load address of the executable. Normally, lldb would be able to find this out on its own by following the breadcrumbs in the process auxiliary vector, but we can't do this here because qemu does not support the qXfer:auxv:read packet. This patch does not implement full scope of the qOffsets packet (it only supports packets with identical code, data and bss offsets), because it is not fully clear how should the different offsets be handled and I am not aware of a producer which would make use of this feature (qemu will always <https://github.com/qemu/qemu/blob/master/linux-user/elfload.c#L2436> return the same value for code and data offsets). In fact, even gdb ignores the offset for the bss sections, and uses the "data" offset instead. So, until the we need more of this packet, I think it's best to stick to the simplest solution possible. This patch simply rejects replies with non-uniform offsets. Reviewers: clayborg, jasonmolenda Subscribers: lldb-commits Tags: #lldb Differential Revision: https://reviews.llvm.org/D74598
545 lines
17 KiB
Python
545 lines
17 KiB
Python
import os
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import os.path
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import threading
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import socket
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import lldb
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import binascii
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import traceback
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from lldbsuite.support import seven
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from lldbsuite.test.lldbtest import *
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from lldbsuite.test import lldbtest_config
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def checksum(message):
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"""
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Calculate the GDB server protocol checksum of the message.
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The GDB server protocol uses a simple modulo 256 sum.
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"""
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check = 0
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for c in message:
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check += ord(c)
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return check % 256
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def frame_packet(message):
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"""
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Create a framed packet that's ready to send over the GDB connection
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channel.
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Framing includes surrounding the message between $ and #, and appending
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a two character hex checksum.
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"""
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return "$%s#%02x" % (message, checksum(message))
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def escape_binary(message):
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"""
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Escape the binary message using the process described in the GDB server
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protocol documentation.
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Most bytes are sent through as-is, but $, #, and { are escaped by writing
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a { followed by the original byte mod 0x20.
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"""
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out = ""
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for c in message:
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d = ord(c)
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if d in (0x23, 0x24, 0x7d):
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out += chr(0x7d)
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out += chr(d ^ 0x20)
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else:
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out += c
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return out
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def hex_encode_bytes(message):
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"""
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Encode the binary message by converting each byte into a two-character
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hex string.
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"""
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out = ""
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for c in message:
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out += "%02x" % ord(c)
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return out
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def hex_decode_bytes(hex_bytes):
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"""
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Decode the hex string into a binary message by converting each two-character
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hex string into a single output byte.
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"""
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out = ""
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hex_len = len(hex_bytes)
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while i < hex_len - 1:
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out += chr(int(hex_bytes[i:i + 2]), 16)
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i += 2
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return out
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class MockGDBServerResponder:
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"""
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A base class for handling client packets and issuing server responses for
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GDB tests.
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This handles many typical situations, while still allowing subclasses to
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completely customize their responses.
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Most subclasses will be interested in overriding the other() method, which
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handles any packet not recognized in the common packet handling code.
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"""
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registerCount = 40
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packetLog = None
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def __init__(self):
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self.packetLog = []
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def respond(self, packet):
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"""
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Return the unframed packet data that the server should issue in response
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to the given packet received from the client.
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"""
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self.packetLog.append(packet)
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if packet is MockGDBServer.PACKET_INTERRUPT:
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return self.interrupt()
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if packet == "c":
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return self.cont()
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if packet.startswith("vCont;c"):
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return self.vCont(packet)
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if packet[0] == "A":
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return self.A(packet)
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if packet[0] == "g":
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return self.readRegisters()
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if packet[0] == "G":
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# Gxxxxxxxxxxx
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# Gxxxxxxxxxxx;thread:1234;
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return self.writeRegisters(packet[1:].split(';')[0])
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if packet[0] == "p":
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regnum = packet[1:].split(';')[0]
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return self.readRegister(int(regnum, 16))
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if packet[0] == "P":
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register, value = packet[1:].split("=")
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return self.writeRegister(int(register, 16), value)
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if packet[0] == "m":
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addr, length = [int(x, 16) for x in packet[1:].split(',')]
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return self.readMemory(addr, length)
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if packet[0] == "M":
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location, encoded_data = packet[1:].split(":")
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addr, length = [int(x, 16) for x in location.split(',')]
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return self.writeMemory(addr, encoded_data)
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if packet[0:7] == "qSymbol":
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return self.qSymbol(packet[8:])
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if packet[0:10] == "qSupported":
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return self.qSupported(packet[11:].split(";"))
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if packet == "qfThreadInfo":
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return self.qfThreadInfo()
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if packet == "qsThreadInfo":
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return self.qsThreadInfo()
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if packet == "qC":
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return self.qC()
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if packet == "QEnableErrorStrings":
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return self.QEnableErrorStrings()
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if packet == "?":
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return self.haltReason()
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if packet == "s":
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return self.haltReason()
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if packet[0] == "H":
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return self.selectThread(packet[1], int(packet[2:], 16))
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if packet[0:6] == "qXfer:":
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obj, read, annex, location = packet[6:].split(":")
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offset, length = [int(x, 16) for x in location.split(',')]
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data, has_more = self.qXferRead(obj, annex, offset, length)
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if data is not None:
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return self._qXferResponse(data, has_more)
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return ""
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if packet.startswith("vAttach;"):
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pid = packet.partition(';')[2]
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return self.vAttach(int(pid, 16))
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if packet[0] == "Z":
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return self.setBreakpoint(packet)
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if packet.startswith("qThreadStopInfo"):
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threadnum = int (packet[15:], 16)
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return self.threadStopInfo(threadnum)
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if packet == "QThreadSuffixSupported":
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return self.QThreadSuffixSupported()
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if packet == "QListThreadsInStopReply":
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return self.QListThreadsInStopReply()
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if packet.startswith("qMemoryRegionInfo:"):
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return self.qMemoryRegionInfo()
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if packet == "qQueryGDBServer":
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return self.qQueryGDBServer()
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if packet == "qHostInfo":
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return self.qHostInfo()
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if packet == "qGetWorkingDir":
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return self.qGetWorkingDir()
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if packet == "qOffsets":
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return self.qOffsets();
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if packet == "qsProcessInfo":
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return self.qsProcessInfo()
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if packet.startswith("qfProcessInfo"):
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return self.qfProcessInfo(packet)
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return self.other(packet)
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def qsProcessInfo(self):
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return "E04"
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def qfProcessInfo(self, packet):
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return "E04"
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def qGetWorkingDir(self):
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return "2f"
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def qOffsets(self):
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return ""
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def qHostInfo(self):
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return "ptrsize:8;endian:little;"
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def qQueryGDBServer(self):
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return "E04"
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def interrupt(self):
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raise self.UnexpectedPacketException()
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def cont(self):
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raise self.UnexpectedPacketException()
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def vCont(self, packet):
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raise self.UnexpectedPacketException()
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def A(self, packet):
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return ""
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def readRegisters(self):
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return "00000000" * self.registerCount
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def readRegister(self, register):
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return "00000000"
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def writeRegisters(self, registers_hex):
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return "OK"
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def writeRegister(self, register, value_hex):
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return "OK"
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def readMemory(self, addr, length):
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return "00" * length
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def writeMemory(self, addr, data_hex):
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return "OK"
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def qSymbol(self, symbol_args):
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return "OK"
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def qSupported(self, client_supported):
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return "qXfer:features:read+;PacketSize=3fff;QStartNoAckMode+"
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def qfThreadInfo(self):
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return "l"
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def qsThreadInfo(self):
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return "l"
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def qC(self):
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return "QC0"
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def QEnableErrorStrings(self):
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return "OK"
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def haltReason(self):
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# SIGINT is 2, return type is 2 digit hex string
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return "S02"
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def qXferRead(self, obj, annex, offset, length):
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return None, False
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def _qXferResponse(self, data, has_more):
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return "%s%s" % ("m" if has_more else "l", escape_binary(data))
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def vAttach(self, pid):
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raise self.UnexpectedPacketException()
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def selectThread(self, op, thread_id):
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return "OK"
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def setBreakpoint(self, packet):
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raise self.UnexpectedPacketException()
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def threadStopInfo(self, threadnum):
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return ""
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def other(self, packet):
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# empty string means unsupported
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return ""
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def QThreadSuffixSupported(self):
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return ""
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def QListThreadsInStopReply(self):
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return ""
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def qMemoryRegionInfo(self):
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return ""
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"""
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Raised when we receive a packet for which there is no default action.
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Override the responder class to implement behavior suitable for the test at
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hand.
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"""
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class UnexpectedPacketException(Exception):
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pass
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class MockGDBServer:
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"""
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A simple TCP-based GDB server that can test client behavior by receiving
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commands and issuing custom-tailored responses.
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Responses are generated via the .responder property, which should be an
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instance of a class based on MockGDBServerResponder.
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"""
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responder = None
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port = 0
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_socket = None
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_client = None
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_thread = None
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_receivedData = None
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_receivedDataOffset = None
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_shouldSendAck = True
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def __init__(self, port = 0):
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self.responder = MockGDBServerResponder()
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self.port = port
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self._socket = socket.socket()
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def start(self):
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# Block until the socket is up, so self.port is available immediately.
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# Then start a thread that waits for a client connection.
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addr = ("127.0.0.1", self.port)
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self._socket.bind(addr)
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self.port = self._socket.getsockname()[1]
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self._socket.listen(1)
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self._thread = threading.Thread(target=self._run)
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self._thread.start()
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def stop(self):
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self._socket.close()
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self._thread.join()
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self._thread = None
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def _run(self):
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# For testing purposes, we only need to worry about one client
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# connecting just one time.
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try:
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# accept() is stubborn and won't fail even when the socket is
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# shutdown, so we'll use a timeout
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self._socket.settimeout(20.0)
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client, client_addr = self._socket.accept()
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self._client = client
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# The connected client inherits its timeout from self._socket,
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# but we'll use a blocking socket for the client
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self._client.settimeout(None)
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except:
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return
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self._shouldSendAck = True
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self._receivedData = ""
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self._receivedDataOffset = 0
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data = None
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while True:
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try:
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data = seven.bitcast_to_string(self._client.recv(4096))
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if data is None or len(data) == 0:
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break
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self._receive(data)
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except Exception as e:
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print("An exception happened when receiving the response from the gdb server. Closing the client...")
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traceback.print_exc()
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self._client.close()
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break
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def _receive(self, data):
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"""
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Collects data, parses and responds to as many packets as exist.
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Any leftover data is kept for parsing the next time around.
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"""
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self._receivedData += data
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try:
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packet = self._parsePacket()
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while packet is not None:
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self._handlePacket(packet)
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packet = self._parsePacket()
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except self.InvalidPacketException:
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self._client.close()
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def _parsePacket(self):
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"""
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Reads bytes from self._receivedData, returning:
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- a packet's contents if a valid packet is found
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- the PACKET_ACK unique object if we got an ack
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- None if we only have a partial packet
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Raises an InvalidPacketException if unexpected data is received
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or if checksums fail.
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Once a complete packet is found at the front of self._receivedData,
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its data is removed form self._receivedData.
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"""
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data = self._receivedData
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i = self._receivedDataOffset
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data_len = len(data)
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if data_len == 0:
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return None
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if i == 0:
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# If we're looking at the start of the received data, that means
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# we're looking for the start of a new packet, denoted by a $.
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# It's also possible we'll see an ACK here, denoted by a +
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if data[0] == '+':
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self._receivedData = data[1:]
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return self.PACKET_ACK
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if ord(data[0]) == 3:
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self._receivedData = data[1:]
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return self.PACKET_INTERRUPT
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if data[0] == '$':
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i += 1
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else:
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raise self.InvalidPacketException(
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"Unexpected leading byte: %s" % data[0])
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# If we're looking beyond the start of the received data, then we're
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# looking for the end of the packet content, denoted by a #.
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# Note that we pick up searching from where we left off last time
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while i < data_len and data[i] != '#':
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i += 1
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# If there isn't enough data left for a checksum, just remember where
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# we left off so we can pick up there the next time around
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if i > data_len - 3:
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self._receivedDataOffset = i
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return None
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# If we have enough data remaining for the checksum, extract it and
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# compare to the packet contents
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packet = data[1:i]
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i += 1
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try:
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check = int(data[i:i + 2], 16)
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except ValueError:
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raise self.InvalidPacketException("Checksum is not valid hex")
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i += 2
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if check != checksum(packet):
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raise self.InvalidPacketException(
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"Checksum %02x does not match content %02x" %
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(check, checksum(packet)))
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# remove parsed bytes from _receivedData and reset offset so parsing
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# can start on the next packet the next time around
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self._receivedData = data[i:]
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self._receivedDataOffset = 0
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return packet
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def _handlePacket(self, packet):
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if packet is self.PACKET_ACK:
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# Ignore ACKs from the client. For the future, we can consider
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# adding validation code to make sure the client only sends ACKs
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# when it's supposed to.
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return
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response = ""
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# We'll handle the ack stuff here since it's not something any of the
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# tests will be concerned about, and it'll get turned off quickly anyway.
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if self._shouldSendAck:
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self._client.sendall(seven.bitcast_to_bytes('+'))
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if packet == "QStartNoAckMode":
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self._shouldSendAck = False
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response = "OK"
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elif self.responder is not None:
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# Delegate everything else to our responder
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response = self.responder.respond(packet)
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# Handle packet framing since we don't want to bother tests with it.
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if response is not None:
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framed = frame_packet(response)
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self._client.sendall(seven.bitcast_to_bytes(framed))
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PACKET_ACK = object()
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PACKET_INTERRUPT = object()
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class InvalidPacketException(Exception):
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pass
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class GDBRemoteTestBase(TestBase):
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"""
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Base class for GDB client tests.
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This class will setup and start a mock GDB server for the test to use.
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It also provides assertPacketLogContains, which simplifies the checking
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of packets sent by the client.
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"""
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NO_DEBUG_INFO_TESTCASE = True
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mydir = TestBase.compute_mydir(__file__)
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server = None
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def setUp(self):
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TestBase.setUp(self)
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self.server = MockGDBServer()
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self.server.start()
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def tearDown(self):
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# TestBase.tearDown will kill the process, but we need to kill it early
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# so its client connection closes and we can stop the server before
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# finally calling the base tearDown.
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if self.process() is not None:
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self.process().Kill()
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self.server.stop()
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TestBase.tearDown(self)
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def createTarget(self, yaml_path):
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"""
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Create a target by auto-generating the object based on the given yaml
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instructions.
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This will track the generated object so it can be automatically removed
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during tearDown.
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"""
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yaml_base, ext = os.path.splitext(yaml_path)
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obj_path = self.getBuildArtifact(yaml_base)
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self.yaml2obj(yaml_path, obj_path)
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return self.dbg.CreateTarget(obj_path)
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def connect(self, target):
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"""
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Create a process by connecting to the mock GDB server.
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Includes assertions that the process was successfully created.
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"""
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listener = self.dbg.GetListener()
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error = lldb.SBError()
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url = "connect://localhost:%d" % self.server.port
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process = target.ConnectRemote(listener, url, "gdb-remote", error)
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self.assertTrue(error.Success(), error.description)
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self.assertTrue(process, PROCESS_IS_VALID)
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return process
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def assertPacketLogContains(self, packets):
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"""
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Assert that the mock server's packet log contains the given packets.
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The packet log includes all packets sent by the client and received
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by the server. This fuction makes it easy to verify that the client
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sent the expected packets to the server.
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The check does not require that the packets be consecutive, but does
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require that they are ordered in the log as they ordered in the arg.
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"""
|
|
i = 0
|
|
j = 0
|
|
log = self.server.responder.packetLog
|
|
|
|
while i < len(packets) and j < len(log):
|
|
if log[j] == packets[i]:
|
|
i += 1
|
|
j += 1
|
|
if i < len(packets):
|
|
self.fail(u"Did not receive: %s\nLast 10 packets:\n\t%s" %
|
|
(packets[i], u'\n\t'.join(log)))
|