userfaultfd: selftests: modify selftest to use /dev/userfaultfd

We clearly want to ensure both userfaultfd(2) and /dev/userfaultfd keep
working into the future, so just run the test twice, using each interface.

Link: https://lkml.kernel.org/r/20220601210951.3916598-4-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Charan Teja Kalla <charante@codeaurora.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry V. Levin <ldv@altlinux.org>
Cc: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
index 4bc24581760da787c5e33e80b293295a3d45d188..ed5e99d21408bd6a8893c1d7de4008eefb81143f 100644 (file)
--- a/tools/testing/selftests/vm/userfaultfd.c
+++ b/tools/testing/selftests/vm/userfaultfd.c
@@ -77,6 +77,9 @@ static int bounces;
 #define TEST_SHMEM     3
 static int test_type;
 
+/* test using /dev/userfaultfd, instead of userfaultfd(2) */
+static bool test_dev_userfaultfd;
+
 /* exercise the test_uffdio_*_eexist every ALARM_INTERVAL_SECS */
 #define ALARM_INTERVAL_SECS 10
 static volatile bool test_uffdio_copy_eexist = true;
@@ -154,12 +157,14 @@ static void usage(void)
                        ret, __LINE__);                         \
        } while (0)
 
-#define err(fmt, ...)                          \
+#define errexit(exitcode, fmt, ...)            \
        do {                                    \
                _err(fmt, ##__VA_ARGS__);       \
-               exit(1);                        \
+               exit(exitcode);                 \
        } while (0)
 
+#define err(fmt, ...) errexit(1, fmt, ##__VA_ARGS__)
+
 static void uffd_stats_reset(struct uffd_stats *uffd_stats,
                             unsigned long n_cpus)
 {
@@ -383,13 +388,31 @@ static void assert_expected_ioctls_present(uint64_t mode, uint64_t ioctls)
        }
 }
 
+static void __userfaultfd_open_dev(void)
+{
+       int fd;
+
+       uffd = -1;
+       fd = open("/dev/userfaultfd", O_RDWR | O_CLOEXEC);
+       if (fd < 0)
+               return;
+
+       uffd = ioctl(fd, USERFAULTFD_IOC_NEW,
+                    O_CLOEXEC | O_NONBLOCK | UFFD_USER_MODE_ONLY);
+       close(fd);
+}
+
 static void userfaultfd_open(uint64_t *features)
 {
        struct uffdio_api uffdio_api;
 
-       uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK | UFFD_USER_MODE_ONLY);
+       if (test_dev_userfaultfd)
+               __userfaultfd_open_dev();
+       else
+               uffd = syscall(__NR_userfaultfd,
+                              O_CLOEXEC | O_NONBLOCK | UFFD_USER_MODE_ONLY);
        if (uffd < 0)
-               err("userfaultfd syscall not available in this kernel");
+               errexit(KSFT_SKIP, "creating userfaultfd failed");
        uffd_flags = fcntl(uffd, F_GETFD, NULL);
 
        uffdio_api.api = UFFD_API;
@@ -1691,6 +1714,12 @@ int main(int argc, char **argv)
        }
        printf("nr_pages: %lu, nr_pages_per_cpu: %lu\n",
               nr_pages, nr_pages_per_cpu);
+
+       test_dev_userfaultfd = false;
+       if (userfaultfd_stress())
+               return 1;
+
+       test_dev_userfaultfd = true;
        return userfaultfd_stress();
 }