selftests/mm: UFFDIO_API test

Add one simple test for UFFDIO_API.  With that, I also added a bunch of
small but handy helpers along the way.

Link: https://lkml.kernel.org/r/20230412164257.328375-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c
index 6857388783be9d51267da556a31862cc87a73678..bb492c2584863d525f926db4baab5f59fcf7de3a 100644 (file)
--- a/tools/testing/selftests/mm/uffd-unit-tests.c
+++ b/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -9,9 +9,116 @@
 
 #ifdef __NR_userfaultfd
 
+static void uffd_test_report(void)
+{
+       printf("Userfaults unit tests: pass=%u, skip=%u, fail=%u (total=%u)\n",
+              ksft_get_pass_cnt(),
+              ksft_get_xskip_cnt(),
+              ksft_get_fail_cnt(),
+              ksft_test_num());
+}
+
+static void uffd_test_pass(void)
+{
+       printf("done\n");
+       ksft_inc_pass_cnt();
+}
+
+#define  uffd_test_start(...)  do {            \
+               printf("Testing ");             \
+               printf(__VA_ARGS__);            \
+               printf("... ");                 \
+               fflush(stdout);                 \
+       } while (0)
+
+#define  uffd_test_fail(...)  do {             \
+               printf("failed [reason: ");     \
+               printf(__VA_ARGS__);            \
+               printf("]\n");                  \
+               ksft_inc_fail_cnt();            \
+       } while (0)
+
+#define  uffd_test_skip(...)  do {             \
+               printf("skipped [reason: ");    \
+               printf(__VA_ARGS__);            \
+               printf("]\n");                  \
+               ksft_inc_xskip_cnt();           \
+       } while (0)
+
+/*
+ * Returns 1 if specific userfaultfd supported, 0 otherwise.  Note, we'll
+ * return 1 even if some test failed as long as uffd supported, because in
+ * that case we still want to proceed with the rest uffd unit tests.
+ */
+static int test_uffd_api(bool use_dev)
+{
+       struct uffdio_api uffdio_api;
+       int uffd;
+
+       uffd_test_start("UFFDIO_API (with %s)",
+                       use_dev ? "/dev/userfaultfd" : "syscall");
+
+       if (use_dev)
+               uffd = uffd_open_dev(UFFD_FLAGS);
+       else
+               uffd = uffd_open_sys(UFFD_FLAGS);
+       if (uffd < 0) {
+               uffd_test_skip("cannot open userfaultfd handle");
+               return 0;
+       }
+
+       /* Test wrong UFFD_API */
+       uffdio_api.api = 0xab;
+       uffdio_api.features = 0;
+       if (ioctl(uffd, UFFDIO_API, &uffdio_api) == 0) {
+               uffd_test_fail("UFFDIO_API should fail with wrong api but didn't");
+               goto out;
+       }
+
+       /* Test wrong feature bit */
+       uffdio_api.api = UFFD_API;
+       uffdio_api.features = BIT_ULL(63);
+       if (ioctl(uffd, UFFDIO_API, &uffdio_api) == 0) {
+               uffd_test_fail("UFFDIO_API should fail with wrong feature but didn't");
+               goto out;
+       }
+
+       /* Test normal UFFDIO_API */
+       uffdio_api.api = UFFD_API;
+       uffdio_api.features = 0;
+       if (ioctl(uffd, UFFDIO_API, &uffdio_api)) {
+               uffd_test_fail("UFFDIO_API should succeed but failed");
+               goto out;
+       }
+
+       /* Test double requests of UFFDIO_API with a random feature set */
+       uffdio_api.features = BIT_ULL(0);
+       if (ioctl(uffd, UFFDIO_API, &uffdio_api) == 0) {
+               uffd_test_fail("UFFDIO_API should reject initialized uffd");
+               goto out;
+       }
+
+       uffd_test_pass();
+out:
+       close(uffd);
+       /* We have a valid uffd handle */
+       return 1;
+}
+
 int main(int argc, char *argv[])
 {
-       return KSFT_PASS;
+       int has_uffd;
+
+       has_uffd = test_uffd_api(false);
+       has_uffd |= test_uffd_api(true);
+
+       if (!has_uffd) {
+               printf("Userfaultfd not supported or unprivileged, skip all tests\n");
+               exit(KSFT_SKIP);
+       }
+       uffd_test_report();
+
+       return ksft_get_fail_cnt() ? KSFT_FAIL : KSFT_PASS;
 }
 
 #else /* __NR_userfaultfd */