diff options
| -rw-r--r-- | scripts/dump-guest-memory.py | 492 |
1 files changed, 325 insertions, 167 deletions
diff --git a/scripts/dump-guest-memory.py b/scripts/dump-guest-memory.py index 2cf73659a1..7acce654bc 100644 --- a/scripts/dump-guest-memory.py +++ b/scripts/dump-guest-memory.py @@ -6,6 +6,7 @@ # # Authors: # Laszlo Ersek <lersek@redhat.com> +# Janosch Frank <frankja@linux.vnet.ibm.com> # # This work is licensed under the terms of the GNU GPL, version 2 or later. See # the COPYING file in the top-level directory. @@ -15,58 +16,303 @@ # "help data" summary), and it should match how other help texts look in # gdb. -import struct +import ctypes UINTPTR_T = gdb.lookup_type("uintptr_t") TARGET_PAGE_SIZE = 0x1000 TARGET_PAGE_MASK = 0xFFFFFFFFFFFFF000 -# Various ELF constants -EM_X86_64 = 62 # AMD x86-64 target machine -ELFDATA2LSB = 1 # little endian -ELFCLASS64 = 2 -ELFMAG = "\x7FELF" -EV_CURRENT = 1 -ET_CORE = 4 -PT_LOAD = 1 -PT_NOTE = 4 - # Special value for e_phnum. This indicates that the real number of # program headers is too large to fit into e_phnum. Instead the real # value is in the field sh_info of section 0. PN_XNUM = 0xFFFF -# Format strings for packing and header size calculation. -ELF64_EHDR = ("4s" # e_ident/magic - "B" # e_ident/class - "B" # e_ident/data - "B" # e_ident/version - "B" # e_ident/osabi - "8s" # e_ident/pad - "H" # e_type - "H" # e_machine - "I" # e_version - "Q" # e_entry - "Q" # e_phoff - "Q" # e_shoff - "I" # e_flags - "H" # e_ehsize - "H" # e_phentsize - "H" # e_phnum - "H" # e_shentsize - "H" # e_shnum - "H" # e_shstrndx - ) -ELF64_PHDR = ("I" # p_type - "I" # p_flags - "Q" # p_offset - "Q" # p_vaddr - "Q" # p_paddr - "Q" # p_filesz - "Q" # p_memsz - "Q" # p_align - ) +EV_CURRENT = 1 + +ELFCLASS32 = 1 +ELFCLASS64 = 2 + +ELFDATA2LSB = 1 +ELFDATA2MSB = 2 + +ET_CORE = 4 + +PT_LOAD = 1 +PT_NOTE = 4 + +EM_386 = 3 +EM_PPC = 20 +EM_PPC64 = 21 +EM_S390 = 22 +EM_AARCH = 183 +EM_X86_64 = 62 + +class ELF(object): + """Representation of a ELF file.""" + + def __init__(self, arch): + self.ehdr = None + self.notes = [] + self.segments = [] + self.notes_size = 0 + self.endianess = None + self.elfclass = ELFCLASS64 + + if arch == 'aarch64-le': + self.endianess = ELFDATA2LSB + self.elfclass = ELFCLASS64 + self.ehdr = get_arch_ehdr(self.endianess, self.elfclass) + self.ehdr.e_machine = EM_AARCH + + elif arch == 'aarch64-be': + self.endianess = ELFDATA2MSB + self.ehdr = get_arch_ehdr(self.endianess, self.elfclass) + self.ehdr.e_machine = EM_AARCH + + elif arch == 'X86_64': + self.endianess = ELFDATA2LSB + self.ehdr = get_arch_ehdr(self.endianess, self.elfclass) + self.ehdr.e_machine = EM_X86_64 + + elif arch == '386': + self.endianess = ELFDATA2LSB + self.elfclass = ELFCLASS32 + self.ehdr = get_arch_ehdr(self.endianess, self.elfclass) + self.ehdr.e_machine = EM_386 + + elif arch == 's390': + self.endianess = ELFDATA2MSB + self.ehdr = get_arch_ehdr(self.endianess, self.elfclass) + self.ehdr.e_machine = EM_S390 + + elif arch == 'ppc64-le': + self.endianess = ELFDATA2LSB + self.ehdr = get_arch_ehdr(self.endianess, self.elfclass) + self.ehdr.e_machine = EM_PPC64 + + elif arch == 'ppc64-be': + self.endianess = ELFDATA2MSB + self.ehdr = get_arch_ehdr(self.endianess, self.elfclass) + self.ehdr.e_machine = EM_PPC64 + + else: + raise gdb.GdbError("No valid arch type specified.\n" + "Currently supported types:\n" + "aarch64-be, aarch64-le, X86_64, 386, s390, " + "ppc64-be, ppc64-le") + + self.add_segment(PT_NOTE, 0, 0) + + def add_note(self, n_name, n_desc, n_type): + """Adds a note to the ELF.""" + + note = get_arch_note(self.endianess, len(n_name), len(n_desc)) + note.n_namesz = len(n_name) + 1 + note.n_descsz = len(n_desc) + note.n_name = n_name.encode() + note.n_type = n_type + + # Desc needs to be 4 byte aligned (although the 64bit spec + # specifies 8 byte). When defining n_desc as uint32 it will be + # automatically aligned but we need the memmove to copy the + # string into it. + ctypes.memmove(note.n_desc, n_desc.encode(), len(n_desc)) + + self.notes.append(note) + self.segments[0].p_filesz += ctypes.sizeof(note) + self.segments[0].p_memsz += ctypes.sizeof(note) + + def add_segment(self, p_type, p_paddr, p_size): + """Adds a segment to the elf.""" + + phdr = get_arch_phdr(self.endianess, self.elfclass) + phdr.p_type = p_type + phdr.p_paddr = p_paddr + phdr.p_filesz = p_size + phdr.p_memsz = p_size + self.segments.append(phdr) + self.ehdr.e_phnum += 1 + + def to_file(self, elf_file): + """Writes all ELF structures to the the passed file. + + Structure: + Ehdr + Segment 0:PT_NOTE + Segment 1:PT_LOAD + Segment N:PT_LOAD + Note 0..N + Dump contents + """ + elf_file.write(self.ehdr) + off = ctypes.sizeof(self.ehdr) + \ + len(self.segments) * ctypes.sizeof(self.segments[0]) + + for phdr in self.segments: + phdr.p_offset = off + elf_file.write(phdr) + off += phdr.p_filesz + + for note in self.notes: + elf_file.write(note) + + +def get_arch_note(endianess, len_name, len_desc): + """Returns a Note class with the specified endianess.""" + + if endianess == ELFDATA2LSB: + superclass = ctypes.LittleEndianStructure + else: + superclass = ctypes.BigEndianStructure + + len_name = len_name + 1 + + class Note(superclass): + """Represents an ELF note, includes the content.""" + + _fields_ = [("n_namesz", ctypes.c_uint32), + ("n_descsz", ctypes.c_uint32), + ("n_type", ctypes.c_uint32), + ("n_name", ctypes.c_char * len_name), + ("n_desc", ctypes.c_uint32 * ((len_desc + 3) // 4))] + return Note() + + +class Ident(ctypes.Structure): + """Represents the ELF ident array in the ehdr structure.""" + + _fields_ = [('ei_mag0', ctypes.c_ubyte), + ('ei_mag1', ctypes.c_ubyte), + ('ei_mag2', ctypes.c_ubyte), + ('ei_mag3', ctypes.c_ubyte), + ('ei_class', ctypes.c_ubyte), + ('ei_data', ctypes.c_ubyte), + ('ei_version', ctypes.c_ubyte), + ('ei_osabi', ctypes.c_ubyte), + ('ei_abiversion', ctypes.c_ubyte), + ('ei_pad', ctypes.c_ubyte * 7)] + + def __init__(self, endianess, elfclass): + self.ei_mag0 = 0x7F + self.ei_mag1 = ord('E') + self.ei_mag2 = ord('L') + self.ei_mag3 = ord('F') + self.ei_class = elfclass + self.ei_data = endianess + self.ei_version = EV_CURRENT + + +def get_arch_ehdr(endianess, elfclass): + """Returns a EHDR64 class with the specified endianess.""" + + if endianess == ELFDATA2LSB: + superclass = ctypes.LittleEndianStructure + else: + superclass = ctypes.BigEndianStructure + + class EHDR64(superclass): + """Represents the 64 bit ELF header struct.""" + + _fields_ = [('e_ident', Ident), + ('e_type', ctypes.c_uint16), + ('e_machine', ctypes.c_uint16), + ('e_version', ctypes.c_uint32), + ('e_entry', ctypes.c_uint64), + ('e_phoff', ctypes.c_uint64), + ('e_shoff', ctypes.c_uint64), + ('e_flags', ctypes.c_uint32), + ('e_ehsize', ctypes.c_uint16), + ('e_phentsize', ctypes.c_uint16), + ('e_phnum', ctypes.c_uint16), + ('e_shentsize', ctypes.c_uint16), + ('e_shnum', ctypes.c_uint16), + ('e_shstrndx', ctypes.c_uint16)] + + def __init__(self): + super(superclass, self).__init__() + self.e_ident = Ident(endianess, elfclass) + self.e_type = ET_CORE + self.e_version = EV_CURRENT + self.e_ehsize = ctypes.sizeof(self) + self.e_phoff = ctypes.sizeof(self) + self.e_phentsize = ctypes.sizeof(get_arch_phdr(endianess, elfclass)) + self.e_phnum = 0 + + + class EHDR32(superclass): + """Represents the 32 bit ELF header struct.""" + + _fields_ = [('e_ident', Ident), + ('e_type', ctypes.c_uint16), + ('e_machine', ctypes.c_uint16), + ('e_version', ctypes.c_uint32), + ('e_entry', ctypes.c_uint32), + ('e_phoff', ctypes.c_uint32), + ('e_shoff', ctypes.c_uint32), + ('e_flags', ctypes.c_uint32), + ('e_ehsize', ctypes.c_uint16), + ('e_phentsize', ctypes.c_uint16), + ('e_phnum', ctypes.c_uint16), + ('e_shentsize', ctypes.c_uint16), + ('e_shnum', ctypes.c_uint16), + ('e_shstrndx', ctypes.c_uint16)] + + def __init__(self): + super(superclass, self).__init__() + self.e_ident = Ident(endianess, elfclass) + self.e_type = ET_CORE + self.e_version = EV_CURRENT + self.e_ehsize = ctypes.sizeof(self) + self.e_phoff = ctypes.sizeof(self) + self.e_phentsize = ctypes.sizeof(get_arch_phdr(endianess, elfclass)) + self.e_phnum = 0 + + # End get_arch_ehdr + if elfclass == ELFCLASS64: + return EHDR64() + else: + return EHDR32() + + +def get_arch_phdr(endianess, elfclass): + """Returns a 32 or 64 bit PHDR class with the specified endianess.""" + + if endianess == ELFDATA2LSB: + superclass = ctypes.LittleEndianStructure + else: + superclass = ctypes.BigEndianStructure + + class PHDR64(superclass): + """Represents the 64 bit ELF program header struct.""" + + _fields_ = [('p_type', ctypes.c_uint32), + ('p_flags', ctypes.c_uint32), + ('p_offset', ctypes.c_uint64), + ('p_vaddr', ctypes.c_uint64), + ('p_paddr', ctypes.c_uint64), + ('p_filesz', ctypes.c_uint64), + ('p_memsz', ctypes.c_uint64), + ('p_align', ctypes.c_uint64)] + + class PHDR32(superclass): + """Represents the 32 bit ELF program header struct.""" + + _fields_ = [('p_type', ctypes.c_uint32), + ('p_offset', ctypes.c_uint32), + ('p_vaddr', ctypes.c_uint32), + ('p_paddr', ctypes.c_uint32), + ('p_filesz', ctypes.c_uint32), + ('p_memsz', ctypes.c_uint32), + ('p_flags', ctypes.c_uint32), + ('p_align', ctypes.c_uint32)] + + # End get_arch_phdr + if elfclass == ELFCLASS64: + return PHDR64() + else: + return PHDR32() + def int128_get64(val): """Returns low 64bit part of Int128 struct.""" @@ -188,20 +434,22 @@ def get_guest_phys_blocks(): class DumpGuestMemory(gdb.Command): """Extract guest vmcore from qemu process coredump. -The sole argument is FILE, identifying the target file to write the -guest vmcore to. +The two required arguments are FILE and ARCH: +FILE identifies the target file to write the guest vmcore to. +ARCH specifies the architecture for which the core will be generated. This GDB command reimplements the dump-guest-memory QMP command in python, using the representation of guest memory as captured in the qemu coredump. The qemu process that has been dumped must have had the -command line option "-machine dump-guest-core=on". +command line option "-machine dump-guest-core=on" which is the default. For simplicity, the "paging", "begin" and "end" parameters of the QMP command are not supported -- no attempt is made to get the guest's internal paging structures (ie. paging=false is hard-wired), and guest memory is always fully dumped. -Only x86_64 guests are supported. +Currently aarch64-be, aarch64-le, X86_64, 386, s390, ppc64-be, +ppc64-le guests are supported. The CORE/NT_PRSTATUS and QEMU notes (that is, the VCPUs' statuses) are not written to the vmcore. Preparing these would require context that is @@ -219,129 +467,39 @@ shape and this command should mostly work.""" super(DumpGuestMemory, self).__init__("dump-guest-memory", gdb.COMMAND_DATA, gdb.COMPLETE_FILENAME) - self.elf64_ehdr_le = struct.Struct("<%s" % ELF64_EHDR) - self.elf64_phdr_le = struct.Struct("<%s" % ELF64_PHDR) + self.elf = None self.guest_phys_blocks = None - def cpu_get_dump_info(self): - # We can't synchronize the registers with KVM post-mortem, and - # the bits in (first_x86_cpu->env.hflags) seem to be stale; they - # may not reflect long mode for example. Hence just assume the - # most common values. This also means that instruction pointer - # etc. will be bogus in the dump, but at least the RAM contents - # should be valid. - self.dump_info = {"d_machine": EM_X86_64, - "d_endian" : ELFDATA2LSB, - "d_class" : ELFCLASS64} - - def encode_elf64_ehdr_le(self): - return self.elf64_ehdr_le.pack( - ELFMAG, # e_ident/magic - self.dump_info["d_class"], # e_ident/class - self.dump_info["d_endian"], # e_ident/data - EV_CURRENT, # e_ident/version - 0, # e_ident/osabi - "", # e_ident/pad - ET_CORE, # e_type - self.dump_info["d_machine"], # e_machine - EV_CURRENT, # e_version - 0, # e_entry - self.elf64_ehdr_le.size, # e_phoff - 0, # e_shoff - 0, # e_flags - self.elf64_ehdr_le.size, # e_ehsize - self.elf64_phdr_le.size, # e_phentsize - self.phdr_num, # e_phnum - 0, # e_shentsize - 0, # e_shnum - 0 # e_shstrndx - ) - - def encode_elf64_note_le(self): - return self.elf64_phdr_le.pack(PT_NOTE, # p_type - 0, # p_flags - (self.memory_offset - - len(self.note)), # p_offset - 0, # p_vaddr - 0, # p_paddr - len(self.note), # p_filesz - len(self.note), # p_memsz - 0 # p_align - ) - - def encode_elf64_load_le(self, offset, start_hwaddr, range_size): - return self.elf64_phdr_le.pack(PT_LOAD, # p_type - 0, # p_flags - offset, # p_offset - 0, # p_vaddr - start_hwaddr, # p_paddr - range_size, # p_filesz - range_size, # p_memsz - 0 # p_align - ) - - def note_init(self, name, desc, type): - # name must include a trailing NUL - namesz = (len(name) + 1 + 3) / 4 * 4 - descsz = (len(desc) + 3) / 4 * 4 - fmt = ("<" # little endian - "I" # n_namesz - "I" # n_descsz - "I" # n_type - "%us" # name - "%us" # desc - % (namesz, descsz)) - self.note = struct.pack(fmt, - len(name) + 1, len(desc), type, name, desc) - - def dump_init(self): - self.guest_phys_blocks = get_guest_phys_blocks() - self.cpu_get_dump_info() - # we have no way to retrieve the VCPU status from KVM - # post-mortem - self.note_init("NONE", "EMPTY", 0) - - # Account for PT_NOTE. - self.phdr_num = 1 - - # We should never reach PN_XNUM for paging=false dumps: there's - # just a handful of discontiguous ranges after merging. - self.phdr_num += len(self.guest_phys_blocks) - assert self.phdr_num < PN_XNUM - - # Calculate the ELF file offset where the memory dump commences: - # - # ELF header - # PT_NOTE - # PT_LOAD: 1 - # PT_LOAD: 2 - # ... - # PT_LOAD: len(self.guest_phys_blocks) - # ELF note - # memory dump - self.memory_offset = (self.elf64_ehdr_le.size + - self.elf64_phdr_le.size * self.phdr_num + - len(self.note)) - - def dump_begin(self, vmcore): - vmcore.write(self.encode_elf64_ehdr_le()) - vmcore.write(self.encode_elf64_note_le()) - running = self.memory_offset + def dump_init(self, vmcore): + """Prepares and writes ELF structures to core file.""" + + # Needed to make crash happy, data for more useful notes is + # not available in a qemu core. + self.elf.add_note("NONE", "EMPTY", 0) + + # We should never reach PN_XNUM for paging=false dumps, + # there's just a handful of discontiguous ranges after + # merging. + # The constant is needed to account for the PT_NOTE segment. + phdr_num = len(self.guest_phys_blocks) + 1 + assert phdr_num < PN_XNUM + for block in self.guest_phys_blocks: - range_size = block["target_end"] - block["target_start"] - vmcore.write(self.encode_elf64_load_le(running, - block["target_start"], - range_size)) - running += range_size - vmcore.write(self.note) + block_size = block["target_end"] - block["target_start"] + self.elf.add_segment(PT_LOAD, block["target_start"], block_size) + + self.elf.to_file(vmcore) def dump_iterate(self, vmcore): + """Writes guest core to file.""" + qemu_core = gdb.inferiors()[0] for block in self.guest_phys_blocks: cur = block["host_addr"] left = block["target_end"] - block["target_start"] print("dumping range at %016x for length %016x" % (cur.cast(UINTPTR_T), left)) + while left > 0: chunk_size = min(TARGET_PAGE_SIZE, left) chunk = qemu_core.read_memory(cur, chunk_size) @@ -349,22 +507,22 @@ shape and this command should mostly work.""" cur += chunk_size left -= chunk_size - def create_vmcore(self, filename): - vmcore = open(filename, "wb") - self.dump_begin(vmcore) - self.dump_iterate(vmcore) - vmcore.close() - def invoke(self, args, from_tty): + """Handles command invocation from gdb.""" + # Unwittingly pressing the Enter key after the command should # not dump the same multi-gig coredump to the same file. self.dont_repeat() argv = gdb.string_to_argv(args) - if len(argv) != 1: - raise gdb.GdbError("usage: dump-guest-memory FILE") + if len(argv) != 2: + raise gdb.GdbError("usage: dump-guest-memory FILE ARCH") + + self.elf = ELF(argv[1]) + self.guest_phys_blocks = get_guest_phys_blocks() - self.dump_init() - self.create_vmcore(argv[0]) + with open(argv[0], "wb") as vmcore: + self.dump_init(vmcore) + self.dump_iterate(vmcore) DumpGuestMemory() |