Now we've made MAP_PRIVATE-mapped /dev/zero mappings truly anonymous, add a VMA userland test to assert that this is the case and everything is as we would expect for an anonymous mapping.
Acked-by: David Hildenbrand (Arm) <[email protected]> Signed-off-by: Lorenzo Stoakes (ARM) <[email protected]> --- tools/testing/vma/tests/mmap.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/tools/testing/vma/tests/mmap.c b/tools/testing/vma/tests/mmap.c index c85bc000d1cb..fa73faff2262 100644 --- a/tools/testing/vma/tests/mmap.c +++ b/tools/testing/vma/tests/mmap.c @@ -45,7 +45,44 @@ static bool test_mmap_region_basic(void) return true; } +static bool test_pure_anon_dev_zero(void) +{ + const vma_flags_t vma_flags = mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT, + VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT); + struct file file = { + .f_op = &zero_fops, + }; + struct mm_struct mm = {}; + struct vm_area_struct *vma; + unsigned long addr; + VMA_ITERATOR(vmi, &mm, 0); + + current->mm = &mm; + + /* + * Map a MAP_PRIVATE-/dev/zero mapping at address 0x300000 with a page + * offset of 0x10, which we expect to be reset to the anonymous page + * offset. + */ + addr = __mmap_region(&file, 0x300000, 0x3000, vma_flags, 0x10, NULL); + ASSERT_EQ(addr, 0x300000); + + /* Assert that it truly is an anonymous mapping. */ + vma = vma_lookup(&mm, addr); + ASSERT_NE(vma, NULL); + ASSERT_TRUE(vma_is_anonymous(vma)); + ASSERT_EQ(vma->vm_file, NULL); + ASSERT_EQ(vma->vm_private_data, NULL); + /* Expect anonymous page offsets. */ + ASSERT_EQ(vma->vm_pgoff, 0x300); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0x300); + + cleanup_mm(&mm, &vmi); + return true; +} + static void run_mmap_tests(int *num_tests, int *num_fail) { TEST(mmap_region_basic); + TEST(pure_anon_dev_zero); } -- 2.55.0
