diff options
Diffstat (limited to 'scripts/gdb/linux/pgtable.py')
| -rw-r--r-- | scripts/gdb/linux/pgtable.py | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/scripts/gdb/linux/pgtable.py b/scripts/gdb/linux/pgtable.py new file mode 100644 index 000000000000..30d837f3dfae --- /dev/null +++ b/scripts/gdb/linux/pgtable.py @@ -0,0 +1,222 @@ +# SPDX-License-Identifier: GPL-2.0-only +# +# gdb helper commands and functions for Linux kernel debugging +# +# routines to introspect page table +# +# Authors: +# Dmitrii Bundin <dmitrii.bundin.a@gmail.com> +# + +import gdb + +from linux import utils + +PHYSICAL_ADDRESS_MASK = gdb.parse_and_eval('0xfffffffffffff') + + +def page_mask(level=1): + # 4KB + if level == 1: + return gdb.parse_and_eval('(u64) ~0xfff') + # 2MB + elif level == 2: + return gdb.parse_and_eval('(u64) ~0x1fffff') + # 1GB + elif level == 3: + return gdb.parse_and_eval('(u64) ~0x3fffffff') + else: + raise Exception(f'Unknown page level: {level}') + + +#page_offset_base in case CONFIG_DYNAMIC_MEMORY_LAYOUT is disabled +POB_NO_DYNAMIC_MEM_LAYOUT = '0xffff888000000000' +def _page_offset_base(): + pob_symbol = gdb.lookup_global_symbol('page_offset_base') + pob = pob_symbol.name if pob_symbol else POB_NO_DYNAMIC_MEM_LAYOUT + return gdb.parse_and_eval(pob) + + +def is_bit_defined_tupled(data, offset): + return offset, bool(data >> offset & 1) + +def content_tupled(data, bit_start, bit_end): + return (bit_start, bit_end), data >> bit_start & ((1 << (1 + bit_end - bit_start)) - 1) + +def entry_va(level, phys_addr, translating_va): + def start_bit(level): + if level == 5: + return 48 + elif level == 4: + return 39 + elif level == 3: + return 30 + elif level == 2: + return 21 + elif level == 1: + return 12 + else: + raise Exception(f'Unknown level {level}') + + entry_offset = ((translating_va >> start_bit(level)) & 511) * 8 + entry_va = _page_offset_base() + phys_addr + entry_offset + return entry_va + +class Cr3(): + def __init__(self, cr3, page_levels): + self.cr3 = cr3 + self.page_levels = page_levels + self.page_level_write_through = is_bit_defined_tupled(cr3, 3) + self.page_level_cache_disabled = is_bit_defined_tupled(cr3, 4) + self.next_entry_physical_address = cr3 & PHYSICAL_ADDRESS_MASK & page_mask() + + def next_entry(self, va): + next_level = self.page_levels + return PageHierarchyEntry(entry_va(next_level, self.next_entry_physical_address, va), next_level) + + def mk_string(self): + return f"""\ +cr3: + {'cr3 binary data': <30} {hex(self.cr3)} + {'next entry physical address': <30} {hex(self.next_entry_physical_address)} + --- + {'bit' : <4} {self.page_level_write_through[0]: <10} {'page level write through': <30} {self.page_level_write_through[1]} + {'bit' : <4} {self.page_level_cache_disabled[0]: <10} {'page level cache disabled': <30} {self.page_level_cache_disabled[1]} +""" + + +class PageHierarchyEntry(): + def __init__(self, address, level): + data = int.from_bytes( + memoryview(gdb.selected_inferior().read_memory(address, 8)), + "little" + ) + if level == 1: + self.is_page = True + self.entry_present = is_bit_defined_tupled(data, 0) + self.read_write = is_bit_defined_tupled(data, 1) + self.user_access_allowed = is_bit_defined_tupled(data, 2) + self.page_level_write_through = is_bit_defined_tupled(data, 3) + self.page_level_cache_disabled = is_bit_defined_tupled(data, 4) + self.entry_was_accessed = is_bit_defined_tupled(data, 5) + self.dirty = is_bit_defined_tupled(data, 6) + self.pat = is_bit_defined_tupled(data, 7) + self.global_translation = is_bit_defined_tupled(data, 8) + self.page_physical_address = data & PHYSICAL_ADDRESS_MASK & page_mask(level) + self.next_entry_physical_address = None + self.hlat_restart_with_ordinary = is_bit_defined_tupled(data, 11) + self.protection_key = content_tupled(data, 59, 62) + self.executed_disable = is_bit_defined_tupled(data, 63) + else: + page_size = is_bit_defined_tupled(data, 7) + page_size_bit = page_size[1] + self.is_page = page_size_bit + self.entry_present = is_bit_defined_tupled(data, 0) + self.read_write = is_bit_defined_tupled(data, 1) + self.user_access_allowed = is_bit_defined_tupled(data, 2) + self.page_level_write_through = is_bit_defined_tupled(data, 3) + self.page_level_cache_disabled = is_bit_defined_tupled(data, 4) + self.entry_was_accessed = is_bit_defined_tupled(data, 5) + self.page_size = page_size + self.dirty = is_bit_defined_tupled( + data, 6) if page_size_bit else None + self.global_translation = is_bit_defined_tupled( + data, 8) if page_size_bit else None + self.pat = is_bit_defined_tupled( + data, 12) if page_size_bit else None + self.page_physical_address = data & PHYSICAL_ADDRESS_MASK & page_mask(level) if page_size_bit else None + self.next_entry_physical_address = None if page_size_bit else data & PHYSICAL_ADDRESS_MASK & page_mask() + self.hlat_restart_with_ordinary = is_bit_defined_tupled(data, 11) + self.protection_key = content_tupled(data, 59, 62) if page_size_bit else None + self.executed_disable = is_bit_defined_tupled(data, 63) + self.address = address + self.page_entry_binary_data = data + self.page_hierarchy_level = level + + def next_entry(self, va): + if self.is_page or not self.entry_present[1]: + return None + + next_level = self.page_hierarchy_level - 1 + return PageHierarchyEntry(entry_va(next_level, self.next_entry_physical_address, va), next_level) + + + def mk_string(self): + if not self.entry_present[1]: + return f"""\ +level {self.page_hierarchy_level}: + {'entry address': <30} {hex(self.address)} + {'page entry binary data': <30} {hex(self.page_entry_binary_data)} + --- + PAGE ENTRY IS NOT PRESENT! +""" + elif self.is_page: + def page_size_line(ps_bit, ps, level): + return "" if level == 1 else f"{'bit': <3} {ps_bit: <5} {'page size': <30} {ps}" + + return f"""\ +level {self.page_hierarchy_level}: + {'entry address': <30} {hex(self.address)} + {'page entry binary data': <30} {hex(self.page_entry_binary_data)} + {'page size': <30} {'1GB' if self.page_hierarchy_level == 3 else '2MB' if self.page_hierarchy_level == 2 else '4KB' if self.page_hierarchy_level == 1 else 'Unknown page size for level:' + self.page_hierarchy_level} + {'page physical address': <30} {hex(self.page_physical_address)} + --- + {'bit': <4} {self.entry_present[0]: <10} {'entry present': <30} {self.entry_present[1]} + {'bit': <4} {self.read_write[0]: <10} {'read/write access allowed': <30} {self.read_write[1]} + {'bit': <4} {self.user_access_allowed[0]: <10} {'user access allowed': <30} {self.user_access_allowed[1]} + {'bit': <4} {self.page_level_write_through[0]: <10} {'page level write through': <30} {self.page_level_write_through[1]} + {'bit': <4} {self.page_level_cache_disabled[0]: <10} {'page level cache disabled': <30} {self.page_level_cache_disabled[1]} + {'bit': <4} {self.entry_was_accessed[0]: <10} {'entry has been accessed': <30} {self.entry_was_accessed[1]} + {"" if self.page_hierarchy_level == 1 else f"{'bit': <4} {self.page_size[0]: <10} {'page size': <30} {self.page_size[1]}"} + {'bit': <4} {self.dirty[0]: <10} {'page dirty': <30} {self.dirty[1]} + {'bit': <4} {self.global_translation[0]: <10} {'global translation': <30} {self.global_translation[1]} + {'bit': <4} {self.hlat_restart_with_ordinary[0]: <10} {'restart to ordinary': <30} {self.hlat_restart_with_ordinary[1]} + {'bit': <4} {self.pat[0]: <10} {'pat': <30} {self.pat[1]} + {'bits': <4} {str(self.protection_key[0]): <10} {'protection key': <30} {self.protection_key[1]} + {'bit': <4} {self.executed_disable[0]: <10} {'execute disable': <30} {self.executed_disable[1]} +""" + else: + return f"""\ +level {self.page_hierarchy_level}: + {'entry address': <30} {hex(self.address)} + {'page entry binary data': <30} {hex(self.page_entry_binary_data)} + {'next entry physical address': <30} {hex(self.next_entry_physical_address)} + --- + {'bit': <4} {self.entry_present[0]: <10} {'entry present': <30} {self.entry_present[1]} + {'bit': <4} {self.read_write[0]: <10} {'read/write access allowed': <30} {self.read_write[1]} + {'bit': <4} {self.user_access_allowed[0]: <10} {'user access allowed': <30} {self.user_access_allowed[1]} + {'bit': <4} {self.page_level_write_through[0]: <10} {'page level write through': <30} {self.page_level_write_through[1]} + {'bit': <4} {self.page_level_cache_disabled[0]: <10} {'page level cache disabled': <30} {self.page_level_cache_disabled[1]} + {'bit': <4} {self.entry_was_accessed[0]: <10} {'entry has been accessed': <30} {self.entry_was_accessed[1]} + {'bit': <4} {self.page_size[0]: <10} {'page size': <30} {self.page_size[1]} + {'bit': <4} {self.hlat_restart_with_ordinary[0]: <10} {'restart to ordinary': <30} {self.hlat_restart_with_ordinary[1]} + {'bit': <4} {self.executed_disable[0]: <10} {'execute disable': <30} {self.executed_disable[1]} +""" + + +class TranslateVM(gdb.Command): + """Prints the entire paging structure used to translate a given virtual address. + +Having an address space of the currently executed process translates the virtual address +and prints detailed information of all paging structure levels used for the transaltion. +Currently supported arch: x86""" + + def __init__(self): + super(TranslateVM, self).__init__('translate-vm', gdb.COMMAND_USER) + + def invoke(self, arg, from_tty): + if utils.is_target_arch("x86"): + vm_address = gdb.parse_and_eval(f'{arg}') + cr3_data = gdb.parse_and_eval('$cr3') + cr4 = gdb.parse_and_eval('$cr4') + page_levels = 5 if cr4 & (1 << 12) else 4 + page_entry = Cr3(cr3_data, page_levels) + while page_entry: + gdb.write(page_entry.mk_string()) + page_entry = page_entry.next_entry(vm_address) + else: + gdb.GdbError("Virtual address translation is not" + "supported for this arch") + + +TranslateVM() |