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# Copyright (c) Meta Platforms, Inc. and affiliates.
# SPDX-License-Identifier: LGPL-2.1-or-later
import contextlib
import ctypes
import mmap
import os
import struct
import sys
import tempfile
import unittest
from _drgn_util.platform import NORMALIZED_MACHINE_NAME
from drgn import NULL, FaultError
from drgn.helpers.linux.mm import (
PFN_PHYS,
PHYS_PFN,
PageCompound,
PageHead,
PageSwapBacked,
PageTail,
PageWriteback,
access_process_vm,
access_remote_vm,
cmdline,
compound_head,
compound_nr,
compound_order,
decode_page_flags,
environ,
find_vmap_area,
follow_page,
follow_pfn,
follow_phys,
for_each_vma,
for_each_vmap_area,
page_size,
page_to_pfn,
page_to_phys,
page_to_virt,
pfn_to_page,
pfn_to_virt,
phys_to_page,
phys_to_virt,
totalram_pages,
virt_to_page,
virt_to_pfn,
virt_to_phys,
vma_find,
vmalloc_to_page,
vmalloc_to_pfn,
)
from drgn.helpers.linux.pid import find_task
from tests.linux_kernel import (
LinuxKernelTestCase,
fork_and_stop,
iter_maps,
mlock,
prng32,
skip_if_highmem,
skip_if_highpte,
skip_unless_have_full_mm_support,
skip_unless_have_test_kmod,
)
class TestMm(LinuxKernelTestCase):
def test_page_constants(self):
self.assertEqual(self.prog["PAGE_SIZE"], mmap.PAGESIZE)
self.assertEqual(1 << self.prog["PAGE_SHIFT"], mmap.PAGESIZE)
self.assertEqual(~self.prog["PAGE_MASK"] + 1, mmap.PAGESIZE)
# Returns an mmap.mmap object for a file mapping in /dev/shm, its mapped
# address, and the pfns backing it.
@contextlib.contextmanager
def _pages(self):
if not os.path.exists("/proc/self/pagemap"):
self.skipTest("kernel does not support pagemap")
pages = 4
with tempfile.TemporaryFile(dir="/dev/shm") as f:
f.write(os.urandom(pages * mmap.PAGESIZE))
f.flush()
with mmap.mmap(f.fileno(), pages * mmap.PAGESIZE) as map:
f.close()
address = ctypes.addressof(ctypes.c_char.from_buffer(map))
# Make sure the pages are faulted in and stay that way.
mlock(address, pages * mmap.PAGESIZE)
with open("/proc/self/pagemap", "rb", buffering=0) as pagemap:
pagemap.seek(address // mmap.PAGESIZE * 8)
pfns = [
entry & ((1 << 54) - 1)
for entry in struct.unpack(f"{pages}Q", pagemap.read(pages * 8))
]
yield map, address, pfns
def test_page_flag_getters(self):
with self._pages() as (map, _, pfns):
page = pfn_to_page(self.prog, pfns[0])
# The page flag getters are generated, so just pick a positive case
# and a negative case to cover all of them.
self.assertTrue(PageSwapBacked(page))
self.assertFalse(PageWriteback(page))
@skip_unless_have_test_kmod
def test_PageCompound(self):
self.assertFalse(PageCompound(self.prog["drgn_test_page"]))
self.assertTrue(PageCompound(self.prog["drgn_test_compound_page"]))
self.assertTrue(PageCompound(self.prog["drgn_test_compound_page"] + 1))
@skip_unless_have_test_kmod
def test_PageHead(self):
self.assertFalse(PageHead(self.prog["drgn_test_page"]))
self.assertTrue(PageHead(self.prog["drgn_test_compound_page"]))
self.assertFalse(PageHead(self.prog["drgn_test_compound_page"] + 1))
@skip_unless_have_test_kmod
def test_PageTail(self):
self.assertFalse(PageTail(self.prog["drgn_test_page"]))
self.assertFalse(PageTail(self.prog["drgn_test_compound_page"]))
self.assertTrue(PageTail(self.prog["drgn_test_compound_page"] + 1))
@skip_unless_have_test_kmod
def test_compound_head(self):
self.assertEqual(
compound_head(self.prog["drgn_test_page"]), self.prog["drgn_test_page"]
)
self.assertEqual(
compound_head(self.prog["drgn_test_compound_page"]),
self.prog["drgn_test_compound_page"],
)
self.assertEqual(
compound_head(self.prog["drgn_test_compound_page"] + 1),
self.prog["drgn_test_compound_page"],
)
@skip_unless_have_test_kmod
def test_compound_order(self):
self.assertEqual(compound_order(self.prog["drgn_test_page"]), 0)
self.assertEqual(compound_order(self.prog["drgn_test_compound_page"]), 1)
@skip_unless_have_test_kmod
def test_compound_nr(self):
self.assertEqual(compound_nr(self.prog["drgn_test_page"]), 1)
self.assertEqual(compound_nr(self.prog["drgn_test_compound_page"]), 2)
@skip_unless_have_test_kmod
def test_page_size(self):
self.assertEqual(page_size(self.prog["drgn_test_page"]), self.prog["PAGE_SIZE"])
self.assertEqual(
page_size(self.prog["drgn_test_compound_page"]), 2 * self.prog["PAGE_SIZE"]
)
@skip_unless_have_full_mm_support
def test_decode_page_flags(self):
with self._pages() as (map, _, pfns):
page = pfn_to_page(self.prog, pfns[0])
self.assertIn("PG_swapbacked", decode_page_flags(page))
@skip_unless_have_test_kmod
def test_PFN_PHYS(self):
self.assertEqual(
PFN_PHYS(self.prog["drgn_test_pfn"]), self.prog["drgn_test_pa"]
)
@skip_unless_have_test_kmod
def test_PHYS_PFN(self):
self.assertEqual(
PHYS_PFN(self.prog["drgn_test_pa"]), self.prog["drgn_test_pfn"]
)
@skip_unless_have_test_kmod
def test_page_to_pfn(self):
self.assertEqual(
page_to_pfn(self.prog["drgn_test_page"]), self.prog["drgn_test_pfn"]
)
@skip_unless_have_test_kmod
def test_page_to_phys(self):
self.assertEqual(
page_to_phys(self.prog["drgn_test_page"]), self.prog["drgn_test_pa"]
)
@skip_unless_have_full_mm_support
@skip_unless_have_test_kmod
def test_page_to_virt(self):
self.assertEqual(
page_to_virt(self.prog["drgn_test_page"]), self.prog["drgn_test_va"]
)
@skip_unless_have_test_kmod
def test_pfn_to_page(self):
self.assertEqual(
pfn_to_page(self.prog["drgn_test_pfn"]), self.prog["drgn_test_page"]
)
@skip_unless_have_full_mm_support
@skip_unless_have_test_kmod
def test_pfn_to_virt(self):
self.assertEqual(
pfn_to_virt(self.prog["drgn_test_pfn"]), self.prog["drgn_test_va"]
)
@skip_unless_have_test_kmod
def test_phys_to_page(self):
self.assertEqual(
phys_to_page(self.prog["drgn_test_pa"]), self.prog["drgn_test_page"]
)
@skip_unless_have_full_mm_support
@skip_unless_have_test_kmod
def test_phys_to_virt(self):
self.assertEqual(
phys_to_virt(self.prog["drgn_test_pa"]), self.prog["drgn_test_va"]
)
@skip_unless_have_full_mm_support
@skip_unless_have_test_kmod
def test_virt_to_page(self):
self.assertEqual(
virt_to_page(self.prog["drgn_test_va"]), self.prog["drgn_test_page"]
)
@skip_unless_have_full_mm_support
@skip_unless_have_test_kmod
def test_virt_to_pfn(self):
self.assertEqual(
virt_to_pfn(self.prog["drgn_test_va"]), self.prog["drgn_test_pfn"]
)
@skip_unless_have_full_mm_support
@skip_unless_have_test_kmod
def test_virt_to_phys(self):
self.assertEqual(
virt_to_phys(self.prog["drgn_test_va"]), self.prog["drgn_test_pa"]
)
@skip_unless_have_test_kmod
def test_read_physical(self):
expected = bytearray()
for x in prng32("PAGE"):
expected.extend(x.to_bytes(4, sys.byteorder))
if len(expected) >= mmap.PAGESIZE:
break
self.assertEqual(
self.prog.read(self.prog["drgn_test_pa"], mmap.PAGESIZE, True), expected
)
@skip_unless_have_full_mm_support
@skip_unless_have_test_kmod
def test_follow_phys(self):
self.assertEqual(
follow_phys(self.prog["init_mm"].address_of_(), self.prog["drgn_test_va"]),
self.prog["drgn_test_pa"],
)
@skip_unless_have_full_mm_support
@skip_unless_have_test_kmod
def test_follow_page(self):
self.assertEqual(
follow_page(self.prog["init_mm"].address_of_(), self.prog["drgn_test_va"]),
self.prog["drgn_test_page"],
)
@skip_unless_have_full_mm_support
@skip_if_highpte
def test_follow_pfn(self):
task = find_task(self.prog, os.getpid())
with self._pages() as (map, address, pfns):
self.assertEqual(follow_pfn(task.mm, address), pfns[0])
@skip_unless_have_full_mm_support
@skip_unless_have_test_kmod
def test_follow_pfn_init_mm(self):
self.assertEqual(
follow_pfn(self.prog["init_mm"].address_of_(), self.prog["drgn_test_va"]),
self.prog["drgn_test_pfn"],
)
@skip_unless_have_full_mm_support
@skip_unless_have_test_kmod
def test_vmalloc_to_page(self):
self.assertEqual(
vmalloc_to_page(self.prog["drgn_test_vmalloc_va"]),
self.prog["drgn_test_vmalloc_page"],
)
@skip_unless_have_full_mm_support
@skip_unless_have_test_kmod
def test_vmalloc_to_pfn(self):
self.assertEqual(
vmalloc_to_pfn(self.prog["drgn_test_vmalloc_va"]),
self.prog["drgn_test_vmalloc_pfn"],
)
@skip_unless_have_test_kmod
def test_find_vmap_area(self):
self.assertEqual(
find_vmap_area(
self.prog, self.prog["drgn_test_vmalloc_va"] + 1234
).va_start.value_(),
self.prog["drgn_test_vmalloc_va"].value_(),
)
with self.subTest("non-vmap address"):
self.assertIdentical(
find_vmap_area(self.prog, self.prog["drgn_test_va"]),
NULL(self.prog, "struct vmap_area *"),
)
@skip_unless_have_test_kmod
def test_for_each_vmap_area(self):
self.assertTrue(
any(
va.va_start.value_() == self.prog["drgn_test_vmalloc_va"].value_()
for va in for_each_vmap_area(self.prog)
)
)
@skip_unless_have_full_mm_support
@skip_if_highmem
def test_access_process_vm(self):
task = find_task(self.prog, os.getpid())
data = b"hello, world"
buf = ctypes.create_string_buffer(data)
address = ctypes.addressof(buf)
self.assertEqual(access_process_vm(task, address, len(data)), data)
self.assertEqual(access_remote_vm(task.mm, address, len(data)), data)
self.assertRaises(FaultError, access_process_vm, task, 0, 8)
@skip_unless_have_full_mm_support
@skip_if_highmem
def test_access_process_vm_big(self):
task = find_task(self.prog, os.getpid())
# 32M = 2**(log2(16K) + log2(16K / 8)), so 32MB + 1 is enough so that
# even with 16KB pages on a 64-bit architecture, we're guaranteed to
# read across two second-level page table entries. (The same for 64KB
# pages is 512MB + 1, which is too big to test reliably in vmtest.)
max_size = 32 * 1024 * 1024 + 1
expected = os.getrandom(max_size)
while len(expected) < max_size:
expected += os.getrandom(max_size - len(expected))
address = ctypes.memmove(expected, expected, 0)
expected = memoryview(expected)
for size in (1, 65537, max_size):
with self.subTest(size=size):
self.assertEqual(
access_process_vm(task, address, size), expected[:size]
)
@skip_unless_have_full_mm_support
def test_access_remote_vm_init_mm(self):
data = self.prog["UTS_RELEASE"].string_()
self.assertEqual(
access_remote_vm(
self.prog["init_mm"].address_of_(),
self.prog["init_uts_ns"].name.release + 0,
len(data),
),
data,
)
@unittest.skipUnless(NORMALIZED_MACHINE_NAME == "x86_64", "machine is not x86_64")
def test_non_canonical_x86_64(self):
task = find_task(self.prog, os.getpid())
data = b"hello, world"
buf = ctypes.create_string_buffer(data)
address = ctypes.addressof(buf)
self.assertRaises(
FaultError, access_process_vm, task, address ^ (1 << 63), len(data)
)
@skip_unless_have_full_mm_support
@skip_if_highmem
def test_cmdline(self):
with open("/proc/self/cmdline", "rb") as f:
proc_cmdline = f.read().split(b"\0")[:-1]
task = find_task(self.prog, os.getpid())
self.assertEqual(cmdline(task), proc_cmdline)
def test_cmdline_kernel_thread(self):
self.assertIsNone(cmdline(find_task(self.prog, 2)))
@skip_unless_have_full_mm_support
@skip_if_highmem
def test_environ(self):
with open("/proc/self/environ", "rb") as f:
proc_environ = f.read().split(b"\0")[:-1]
task = find_task(self.prog, os.getpid())
self.assertEqual(environ(task), proc_environ)
def test_environ_kernel_thread(self):
self.assertIsNone(environ(find_task(self.prog, 2)))
def test_vma_find(self):
with fork_and_stop() as pid:
mm = find_task(self.prog, pid).mm
prev_end = 0
for map in iter_maps(pid):
# Gate VMAs are not included in vma_find().
if map.is_gate():
continue
if map.start != prev_end:
self.assertIdentical(
vma_find(mm, prev_end),
NULL(self.prog, "struct vm_area_struct *"),
)
self.assertIdentical(
vma_find(mm, map.start - 1),
NULL(self.prog, "struct vm_area_struct *"),
)
vma = vma_find(mm, map.start)
self.assertEqual((map.start, map.end), (vma.vm_start, vma.vm_end))
vma = vma_find(mm, (map.start + map.end) // 2)
self.assertEqual((map.start, map.end), (vma.vm_start, vma.vm_end))
vma = vma_find(mm, map.end - 1)
self.assertEqual((map.start, map.end), (vma.vm_start, vma.vm_end))
prev_end = map.end
self.assertIdentical(
vma_find(mm, prev_end), NULL(self.prog, "struct vm_area_struct *")
)
def test_for_each_vma(self):
with fork_and_stop() as pid:
self.assertEqual(
[
(vma.vm_start, vma.vm_end)
for vma in for_each_vma(find_task(self.prog, pid).mm)
],
[
(map.start, map.end)
for map in iter_maps(pid)
# Gate VMAs are not included in for_each_vma().
if not map.is_gate()
],
)
def test_totalram_pages(self):
with open("/proc/meminfo") as f:
lines = f.read().splitlines()
line = [line for line in lines if line.startswith("MemTotal:")][0]
parts = line.split()
self.assertEqual(parts[2], "kB")
proc_totalram = 1024 * int(parts[1])
page_size = self.prog["PAGE_SIZE"].value_()
self.assertEqual(totalram_pages(self.prog) * page_size, proc_totalram)
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