def _translate_entry(self, offset: int) -> Tuple[int, int]:
"""Translates a specific offset based on paging tables.
Returns the translated entry value
"""
# Setup the entry and how far we are through the offset
# Position maintains the number of bits left to process
# We or with 0x1 to ensure our page_map_offset is always valid
position = self._initial_position
entry = self._initial_entry
# Run through the offset in various chunks
for (name, size, large_page) in self._structure:
# Check we're valid
if not self._page_is_valid(entry):
raise exceptions.PagedInvalidAddressException(self.name, offset, position + 1, entry,
"Page Fault at entry " + hex(entry) + " in table " + name)
# Check if we're a large page
if large_page and (entry & (1 << 7)):
# We're a large page, the rest is finished below
# If we want to implement PSE-36, it would need to be done here
break
# Figure out how much of the offset we should be using
start = position
position -= size
index = self._mask(offset, start, position + 1) >> (position + 1)
# Grab the base address of the table we'll be getting the next entry from
base_address = self._mask(entry, self._maxphyaddr - 1, size + self._index_shift)
table = self._get_valid_table(base_address)
if table is None:
raise exceptions.PagedInvalidAddressException(self.name, offset, position + 1, entry,
"Page Fault at entry " + hex(entry) + " in table " + name)
# Read the data for the next entry
entry_data = table[(index << self._index_shift):(index << self._index_shift) + self._entry_size]
if INTEL_TRANSLATION_DEBUGGING:
vollog.log(
constants.LOGLEVEL_VVVV, "Entry {} at index {} gives data {} as {}".format(
hex(entry), hex(index), hex(struct.unpack(self._entry_format, entry_data)[0]), name))
# Read out the new entry from memory
entry, = struct.unpack(self._entry_format, entry_data)
return entry, position
def _translate(self, offset: int) -> Tuple[int, int, str]:
"""Translates a specific offset based on paging tables.
Returns the translated offset, the contiguous pagesize that the
translated address lives in and the layer_name that the address
lives in
"""
entry, position = self._translate_entry(offset)
# Now we're done
if not self._page_is_valid(entry):
raise exceptions.PagedInvalidAddressException(self.name, offset, position + 1, entry,
"Page Fault at entry {} in page entry".format(hex(entry)))
page = self._mask(entry, self._maxphyaddr - 1, position + 1) | self._mask(offset, position, 0)
return page, 1 << (position + 1), self._base_layer