Commit 84f49284 authored by Lorenzo Stoakes (Oracle)'s avatar Lorenzo Stoakes (Oracle) Committed by Andrew Morton
Browse files

tools/testing/selftests: add merge test for partial msealed range 

Commit 2697dd8a ("mm/mseal: update VMA end correctly on merge") fixed
an issue in the loop which iterates through VMAs applying mseal, which was
triggered by mseal()'ing a range of VMAs where the second was mseal()'d
and the first mergeable with it, once mseal()'d.

Add a regression test to assert that this behaviour is correct.  We place
it in the merge selftests as this is strictly an issue with merging (via a
vma_modify() invocation).

It also asserts that mseal()'d ranges are correctly merged as you'd
expect.

The test is implemented such that it is skipped if mseal() is not
available on the system.

[rppt@kernel.org: fix inclusions, to fix handle_uprobe_upon_merged_vma()]
  Link: https://lore.kernel.org/ac_mCIUQWRAbuH8F@kernel.org
[ljs@kernel.org: simplifications per Pedro]
  Link: https://lore.kernel.org/1c9c922d-5cb5-4cff-9273-b737cdb57ca1@lucifer.local
Link: https://lore.kernel.org/20260331073627.50010-1-ljs@kernel.org


Signed-off-by: default avatarLorenzo Stoakes (Oracle) <ljs@kernel.org>
Signed-off-by: default avatarMike Rapoport <rppt@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 6fae274c

tools/testing/selftests/mm/merge.c

+88 −0
Original line number Diff line number Diff line
@@ -48,6 +48,19 @@ static pid_t do_fork(struct procmap_fd *procmap) 
	return 0;

}



#ifdef __NR_mseal

static int sys_mseal(void *ptr, size_t len, unsigned long flags)

{

	return syscall(__NR_mseal, (unsigned long)ptr, len, flags);

}

#else

static int sys_mseal(void *ptr, size_t len, unsigned long flags)

{

	errno = ENOSYS;

	return -1;

}

#endif



FIXTURE_SETUP(merge)

{

	self->page_size = psize();
@@ -1217,6 +1230,81 @@ TEST_F(merge, mremap_correct_placed_faulted) 
	ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 15 * page_size);

}



TEST_F(merge, merge_vmas_with_mseal)

{

	unsigned int page_size = self->page_size;

	struct procmap_fd *procmap = &self->procmap;

	char *ptr, *ptr2, *ptr3;

	/* We need our own as cannot munmap() once sealed. */

	char *carveout;



	/* Invalid mseal() call to see if implemented. */

	ASSERT_EQ(sys_mseal(NULL, 0, ~0UL), -1);

	if (errno == ENOSYS)

		SKIP(return, "mseal not supported, skipping.");



	/* Map carveout. */

	carveout = mmap(NULL, 5 * page_size, PROT_NONE,

			MAP_PRIVATE | MAP_ANON, -1, 0);

	ASSERT_NE(carveout, MAP_FAILED);



	/*

	 * Map 3 separate VMAs:

	 *

	 * |-----------|-----------|-----------|

	 * |    RW     |    RWE    |    RO     |

	 * |-----------|-----------|-----------|

	 *      ptr         ptr2        ptr3

	 */

	ptr = mmap(&carveout[page_size], page_size, PROT_READ | PROT_WRITE,

		   MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0);

	ASSERT_NE(ptr, MAP_FAILED);

	ptr2 = mmap(&carveout[2 * page_size], page_size,

		    PROT_READ | PROT_WRITE | PROT_EXEC,

		   MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0);

	ASSERT_NE(ptr2, MAP_FAILED);

	ptr3 = mmap(&carveout[3 * page_size], page_size, PROT_READ,

		   MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0);

	ASSERT_NE(ptr3, MAP_FAILED);



	/*

	 * mseal the second VMA:

	 *

	 * |-----------|-----------|-----------|

	 * |    RW     |    RWES   |    RO     |

	 * |-----------|-----------|-----------|

	 *      ptr         ptr2        ptr3

	 */

	ASSERT_EQ(sys_mseal(ptr2, page_size, 0), 0);



	/* Make first VMA mergeable upon mseal. */

	ASSERT_EQ(mprotect(ptr, page_size,

			   PROT_READ | PROT_WRITE | PROT_EXEC), 0);

	/*

	 * At this point we have:

	 *

	 * |-----------|-----------|-----------|

	 * |    RWE    |    RWES   |    RO     |

	 * |-----------|-----------|-----------|

	 *      ptr         ptr2        ptr3

	 *

	 * Now mseal all of the VMAs.

	 */

	ASSERT_EQ(sys_mseal(ptr, 3 * page_size, 0), 0);



	/*

	 * We should end up with:

	 *

	 * |-----------------------|-----------|

	 * |          RWES         |    ROS    |

	 * |-----------------------|-----------|

	 *            ptr               ptr3

	 */

	ASSERT_TRUE(find_vma_procmap(procmap, ptr));

	ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr);

	ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 2 * page_size);

}



TEST_F(merge_with_fork, mremap_faulted_to_unfaulted_prev)

{

	struct procmap_fd *procmap = &self->procmap;