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