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-rw-r--r--scripts/gdb/linux/pgtable.py222
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diff --git a/scripts/gdb/linux/pgtable.py b/scripts/gdb/linux/pgtable.py
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+++ b/scripts/gdb/linux/pgtable.py
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+# 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()