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 <axelrasmussen@xxxxxxxxxx>
---
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
