Previously, we just allocated two shm areas: area_src and area_dst. With this commit, change this so we also allocate area_src_alias, and area_dst_alias.
area_*_alias and area_* (respectively) point to the same underlying physical pages, but are different VMAs. In a future commit in this series, we'll leverage this setup to exercise minor fault handling support for shmem, just like we do in the hugetlb_shared test. Signed-off-by: Axel Rasmussen <[email protected]> --- tools/testing/selftests/vm/userfaultfd.c | 29 +++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c index 859398efb4fe..4a18590fe0f8 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -298,8 +298,9 @@ static int shmem_release_pages(char *rel_area) static void shmem_allocate_area(void **alloc_area) { - unsigned long offset = - alloc_area == (void **)&area_src ? 0 : nr_pages * page_size; + void *area_alias = NULL; + bool is_src = alloc_area == (void **)&area_src; + unsigned long offset = is_src ? 0 : nr_pages * page_size; *alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, offset); @@ -308,12 +309,34 @@ static void shmem_allocate_area(void **alloc_area) goto fail; } + area_alias = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE, + MAP_SHARED, shm_fd, offset); + if (area_alias == MAP_FAILED) { + perror("mmap of memfd alias failed"); + goto fail_munmap; + } + + if (is_src) + area_src_alias = area_alias; + else + area_dst_alias = area_alias; + return; +fail_munmap: + if (munmap(*alloc_area, nr_pages * page_size) < 0) { + perror("munmap of memfd failed\n"); + exit(1); + } fail: *alloc_area = NULL; } +static void shmem_alias_mapping(__u64 *start, size_t len, unsigned long offset) +{ + *start = (unsigned long)area_dst_alias + offset; +} + struct uffd_test_ops { unsigned long expected_ioctls; void (*allocate_area)(void **alloc_area); @@ -341,7 +364,7 @@ static struct uffd_test_ops shmem_uffd_test_ops = { .expected_ioctls = SHMEM_EXPECTED_IOCTLS, .allocate_area = shmem_allocate_area, .release_pages = shmem_release_pages, - .alias_mapping = noop_alias_mapping, + .alias_mapping = shmem_alias_mapping, }; static struct uffd_test_ops hugetlb_uffd_test_ops = { -- 2.30.1.766.gb4fecdf3b7-goog
