nagai/kernel
3
0
Fork 0
forked from mirrors/linux
Code Pull requests Activity
kernel/scripts/gdb/linux/mm.py
Dmitrii Bundin e36903b0c1 scripts/gdb: add mm introspection utils 
This command provides a way to traverse the entire page hierarchy by a
given virtual address on x86.  In addition to qemu's commands info
tlb/info mem it provides the complete information about the paging
structure for an arbitrary virtual address.  It supports 4KB/2MB/1GB and 5
level paging.

Here is an example output for 2MB success translation:

(gdb) translate-vm address
cr3:
    cr3 binary data                0x1085be003
    next entry physical address   0x1085be000
    ---
    bit  3          page level write through       False
    bit  4          page level cache disabled      False
level 4:
    entry address                  0xffff8881085be7f8
    page entry binary data         0x800000010ac83067
    next entry physical address   0x10ac83000
    ---
    bit  0          entry present                  True
    bit  1          read/write access allowed      True
    bit  2          user access allowed            True
    bit  3          page level write through       False
    bit  4          page level cache disabled      False
    bit  5          entry has been accessed        True
    bit  7          page size                      False
    bit  11         restart to ordinary            False
    bit  63         execute disable                True
level 3:
    entry address                  0xffff88810ac83a48
    page entry binary data         0x101af7067
    next entry physical address   0x101af7000
    ---
    bit  0          entry present                  True
    bit  1          read/write access allowed      True
    bit  2          user access allowed            True
    bit  3          page level write through       False
    bit  4          page level cache disabled      False
    bit  5          entry has been accessed        True
    bit  7          page size                      False
    bit  11         restart to ordinary            False
    bit  63         execute disable                False
level 2:
    entry address                  0xffff888101af7368
    page entry binary data         0x80000001634008e7
    page size                      2MB
    page physical address         0x163400000
    ---
    bit  0          entry present                  True
    bit  1          read/write access allowed      True
    bit  2          user access allowed            True
    bit  3          page level write through       False
    bit  4          page level cache disabled      False
    bit  5          entry has been accessed        True
    bit  7          page size                      True
    bit  6          page dirty                     True
    bit  8          global translation             False
    bit  11         restart to ordinary            True
    bit  12         pat                            False
    bits (59, 62)   protection key                 0
    bit  63         execute disable                True

[dmitrii.bundin.a@gmail.com: add SPDX line, other tweaks]
  Link: https://lkml.kernel.org/r/20230113175151.22278-1-dmitrii.bundin.a@gmail.com
[akpm@linux-foundation.org: s/physicall/physical/]
Link: https://lkml.kernel.org/r/20230102171014.31408-1-dmitrii.bundin.a@gmail.com
Signed-off-by: Dmitrii Bundin <dmitrii.bundin.a@gmail.com>
Acked by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Kieran Bingham <kbingham@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-02 22:50:03 -08:00

222 lines
10 KiB
Python
Raw Blame History

# 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()
View git blame Copy permalink