366 lines
11 KiB
Python
366 lines
11 KiB
Python
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"""
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Allows loading TianoCore symbols into a GDB session attached to EFI
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Firmware.
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This is how it works: build GdbSyms - it's a dummy binary that
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contains the relevant symbols needed to find and load image symbols.
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$ gdb
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(gdb) taget remote ....
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(gdb) source Scripts/gdb_uefi.py
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(gdb) reload-uefi -o /path/to/GdbSyms.dll
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The -o option should be used if you've debugging EFI, where the PE
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images were converted from MACH-O or ELF binaries.
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"""
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import array
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import getopt
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import binascii
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import re
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__license__ = "BSD"
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__version = "1.0.0"
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__maintainer__ = "Andrei Warkentin"
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__email__ = "andrey.warkentin@gmail.com"
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__status__ = "Works"
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# FOR RPM PACKAGE replace the strings in the spec file
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build_path="__BUILD_PATH__"
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source_path="__SOURCE_PATH__"
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gdb_src_path="__GDB_SRC_PATH__"
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flavor="__FLAVOR__"
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class ReloadUefi (gdb.Command):
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"""Reload UEFI symbols"""
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#
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# Various constants.
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#
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EINVAL = 0xffffffff
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CV_NB10 = 0x3031424E
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CV_RSDS = 0x53445352
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CV_MTOC = 0x434F544D
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DOS_MAGIC = 0x5A4D
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PE32PLUS_MAGIC = 0x20b
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EST_SIGNATURE = 0x5453595320494249L
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DEBUG_GUID = [0x49152E77, 0x1ADA, 0x4764,
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[0xB7,0xA2,0x7A,0xFE,
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0xFE,0xD9,0x5E, 0x8B]]
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DEBUG_IS_UPDATING = 0x1
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#
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# If the images were built as ELF/MACH-O and then converted to PE,
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# then the base address needs to be offset by PE headers.
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#
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offset_by_headers = False
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def __init__ (self):
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super (ReloadUefi, self).__init__ ("reload-uefi", gdb.COMMAND_OBSCURE)
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#
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# Returns gdb.Type for a type.
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#
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def type (self, typename):
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return gdb.lookup_type (typename)
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#
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# Returns gdb.Type for a pointer to a type.
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#
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def ptype (self, typename):
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return gdb.lookup_type (typename).pointer ()
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#
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# Computes CRC32 on an array of data.
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#
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def crc32 (self, data):
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return binascii.crc32 (data) & 0xFFFFFFFF
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#
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# Sets a field in a struct to a value, i.e.
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# value->field_name = data.
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#
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# Newer Py bindings to Gdb provide access to the inferior
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# memory, but not all, so have to do it this awkward way.
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#
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def set_field (self, value, field_name, data):
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gdb.execute ("set *(%s *) 0x%x = 0x%x" % \
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(str (value[field_name].type), \
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long (value[field_name].address), \
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data))
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#
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# Returns data backing a gdb.Value as an array.
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# Same comment as above regarding newer Py bindings...
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#
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def value_data (self, value, bytes=0):
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value_address = gdb.Value (value.address)
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array_t = self.ptype ('UINT8')
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value_array = value_address.cast (array_t)
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if bytes == 0:
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bytes = value.type.sizeof
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data = array.array ('B')
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for i in range (0, bytes):
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data.append (value_array[i])
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return data
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#
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# Locates the EFI_SYSTEM_TABLE as per UEFI spec 17.4.
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# Returns base address or -1.
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#
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def search_est (self):
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address = 0
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estp_t = self.ptype ('EFI_SYSTEM_TABLE_POINTER')
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while True:
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estp = gdb.Value(address).cast(estp_t)
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if estp['Signature'] == self.EST_SIGNATURE:
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oldcrc = long (estp['Crc32'])
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self.set_field (estp, 'Crc32', 0)
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newcrc = self.crc32 (self.value_data (estp.dereference (), 0))
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self.set_field (estp, 'Crc32', long (oldcrc))
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if newcrc == oldcrc:
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return estp['EfiSystemTableBase']
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address = address + 4*1024*1024
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if long (address) == 0:
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return gdb.Value(self.EINVAL)
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#
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# Searches for a vendor-specific configuration table (in EST),
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# given a vendor-specific table GUID. GUID is a list like -
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# [32-bit, 16-bit, 16-bit, [8 bytes]]
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#
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def search_config (self, cfg_table, count, guid):
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index = 0
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while index != count:
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cfg_entry = cfg_table[index]['VendorGuid']
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if cfg_entry['Data1'] == guid[0] and \
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cfg_entry['Data2'] == guid[1] and \
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cfg_entry['Data3'] == guid[2] and \
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self.value_data (cfg_entry['Data4']).tolist () == guid[3]:
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return cfg_table[index]['VendorTable']
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index = index + 1
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return gdb.Value(self.EINVAL)
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#
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# Returns a UTF16 string corresponding to a (CHAR16 *) value in EFI.
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#
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def parse_utf16 (self, value):
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index = 0
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data = array.array ('H')
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while value[index] != 0:
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data.append (value[index])
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index = index + 1
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return data.tostring ().decode ('utf-16')
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#
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# Returns offset of a field within structure. Useful
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# for getting container of a structure.
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#
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def offsetof (self, typename, field):
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t = gdb.Value (0).cast (self.ptype (typename))
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return long (t[field].address)
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#
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# Returns sizeof of a type.
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#
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def sizeof (self, typename):
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return self.type (typename).sizeof
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#
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# Returns the EFI_IMAGE_NT_HEADERS32 pointer, given
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# an ImageBase address as a gdb.Value.
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#
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def pe_headers (self, imagebase):
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dosh_t = self.ptype ('EFI_IMAGE_DOS_HEADER')
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head_t = self.ptype ('EFI_IMAGE_OPTIONAL_HEADER_UNION')
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dosh = imagebase.cast(dosh_t)
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h_addr = imagebase
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if dosh['e_magic'] == self.DOS_MAGIC:
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h_addr = h_addr + dosh['e_lfanew']
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return gdb.Value(h_addr).cast (head_t)
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#
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# Returns True if pe_headers refer to a PE32+ image.
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#
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def pe_is_64 (self, pe_headers):
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if pe_headers['Pe32']['OptionalHeader']['Magic'] == self.PE32PLUS_MAGIC:
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return True
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return False
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#
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# Returns the PE (not so) optional header.
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#
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def pe_optional (self, pe):
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if self.pe_is_64 (pe):
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return pe['Pe32Plus']['OptionalHeader']
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else:
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return pe['Pe32']['OptionalHeader']
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#
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# Returns the symbol file name for a PE image.
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#
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def pe_parse_debug (self, pe):
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opt = self.pe_optional (pe)
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debug_dir_entry = opt['DataDirectory'][6]
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dep = debug_dir_entry['VirtualAddress'] + opt['ImageBase']
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dep = dep.cast (self.ptype ('EFI_IMAGE_DEBUG_DIRECTORY_ENTRY'))
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cvp = dep.dereference ()['RVA'] + opt['ImageBase']
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cvv = cvp.cast(self.ptype ('UINT32')).dereference ()
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if cvv == self.CV_NB10:
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return cvp + self.sizeof('EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY')
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elif cvv == self.CV_RSDS:
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return cvp + self.sizeof('EFI_IMAGE_DEBUG_CODEVIEW_RSDS_ENTRY')
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elif cvv == self.CV_MTOC:
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return cvp + self.sizeof('EFI_IMAGE_DEBUG_CODEVIEW_MTOC_ENTRY')
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return gdb.Value(self.EINVAL)
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#
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# Parses an EFI_LOADED_IMAGE_PROTOCOL, figuring out the symbol file name.
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# This file name is then appended to list of loaded symbols.
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#
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# TBD: Support TE images.
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#
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def parse_image (self, image, syms):
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base = image['ImageBase']
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pe = self.pe_headers (base)
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opt = self.pe_optional (pe)
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sym_name = self.pe_parse_debug (pe)
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# For ELF and Mach-O-derived images...
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if self.offset_by_headers:
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base = base + opt['SizeOfHeaders']
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if sym_name != self.EINVAL:
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sym_name = sym_name.cast (self.ptype('CHAR8')).string ()
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# Ignore the driver from qemu
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if re.search (r"\.efidrv$", sym_name):
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return
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# FOR RPM PACKAGE substitute the build path
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sym_name = re.sub(r"^"+re.escape(build_path), "/usr/lib/debug/"+flavor, sym_name)
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sym_name = re.sub(r"\.dll$", ".debug", sym_name)
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syms.append ("add-symbol-file %s 0x%x" % \
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(sym_name,
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long (base)))
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#
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# Parses table EFI_DEBUG_IMAGE_INFO structures, builds
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# a list of add-symbol-file commands, and reloads debugger
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# symbols.
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#
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def parse_edii (self, edii, count):
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index = 0
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syms = []
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while index != count:
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entry = edii[index]
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if entry['ImageInfoType'].dereference () == 1:
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entry = entry['NormalImage']
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self.parse_image(entry['LoadedImageProtocolInstance'], syms)
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else:
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print "Skipping unknown EFI_DEBUG_IMAGE_INFO (Type 0x%x)" % \
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entry['ImageInfoType'].dereference ()
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index = index + 1
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gdb.execute ("symbol-file")
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print "Loading new symbols..."
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for sym in syms:
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print sym
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gdb.execute (sym)
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#
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# Parses EFI_DEBUG_IMAGE_INFO_TABLE_HEADER, in order to load
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# image symbols.
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#
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def parse_dh (self, dh):
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dh_t = self.ptype ('EFI_DEBUG_IMAGE_INFO_TABLE_HEADER')
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dh = dh.cast (dh_t)
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print "DebugImageInfoTable @ 0x%x, 0x%x entries" \
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% (long (dh['EfiDebugImageInfoTable']), dh['TableSize'])
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if dh['UpdateStatus'] & self.DEBUG_IS_UPDATING:
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print "EfiDebugImageInfoTable update in progress, retry later"
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return
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self.parse_edii (dh['EfiDebugImageInfoTable'], dh['TableSize'])
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#
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# Parses EFI_SYSTEM_TABLE, in order to load image symbols.
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#
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def parse_est (self, est):
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est_t = self.ptype ('EFI_SYSTEM_TABLE')
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est = est.cast (est_t)
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print "Connected to %s (Rev. 0x%x)" % \
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(self.parse_utf16 (est['FirmwareVendor']), \
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long (est['FirmwareRevision']))
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print "ConfigurationTable @ 0x%x, 0x%x entries" \
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% (long (est['ConfigurationTable']), est['NumberOfTableEntries'])
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dh = self.search_config(est['ConfigurationTable'],
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est['NumberOfTableEntries'],
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self.DEBUG_GUID)
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if dh == self.EINVAL:
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print "No EFI_DEBUG_IMAGE_INFO_TABLE_HEADER"
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return
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self.parse_dh (dh)
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#
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# Usage information.
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#
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def usage (self):
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print "Usage: reload-uefi [-o] /path/to/GdbSyms.dll"
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#
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# Handler for reload-uefi.
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#
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def invoke (self, arg, from_tty):
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args = arg.split(' ')
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try:
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opts, args = getopt.getopt(args, "o", ["offset-by-headers"])
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except getopt.GetoptError, err:
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self.usage ()
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return
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for opt, arg in opts:
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if opt == "-o":
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self.offset_by_headers = True
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if len(args) < 1:
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self.usage ()
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return
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# FOR RPM PACKAGE substitute the path of the source code
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gdb.execute ("set substitute-path "+source_path+" "+gdb_src_path)
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gdb.execute ("symbol-file")
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gdb.execute ("symbol-file %s" % args[0])
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est = self.search_est ()
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if est == self.EINVAL:
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print "No EFI_SYSTEM_TABLE..."
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return
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print "EFI_SYSTEM_TABLE @ 0x%x" % est
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self.parse_est (est)
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ReloadUefi ()
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