diff options
Diffstat (limited to 'tools/testing/selftests/mm/uffd-unit-tests.c')
| -rw-r--r-- | tools/testing/selftests/mm/uffd-unit-tests.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c index e8fd9011c2a3..c73fd5d455c8 100644 --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -1231,6 +1231,182 @@ static void uffd_move_pmd_split_test(uffd_test_args_t *targs) uffd_move_pmd_handle_fault); } +static bool +uffdio_verify_results(const char *name, int ret, int error, long result) +{ + /* + * Should always return -1 with errno=EAGAIN, with corresponding + * result field updated in ioctl() args to be -EAGAIN too + * (e.g. copy.copy field for UFFDIO_COPY). + */ + if (ret != -1) { + uffd_test_fail("%s should have returned -1", name); + return false; + } + + if (error != EAGAIN) { + uffd_test_fail("%s should have errno==EAGAIN", name); + return false; + } + + if (result != -EAGAIN) { + uffd_test_fail("%s should have been updated for -EAGAIN", + name); + return false; + } + + return true; +} + +/* + * This defines a function to test one ioctl. Note that here "field" can + * be 1 or anything not -EAGAIN. With that initial value set, we can + * verify later that it should be updated by kernel (when -EAGAIN + * returned), by checking whether it is also updated to -EAGAIN. + */ +#define DEFINE_MMAP_CHANGING_TEST(name, ioctl_name, field) \ + static bool uffdio_mmap_changing_test_##name(int fd) \ + { \ + int ret; \ + struct uffdio_##name args = { \ + .field = 1, \ + }; \ + ret = ioctl(fd, ioctl_name, &args); \ + return uffdio_verify_results(#ioctl_name, ret, errno, args.field); \ + } + +DEFINE_MMAP_CHANGING_TEST(zeropage, UFFDIO_ZEROPAGE, zeropage) +DEFINE_MMAP_CHANGING_TEST(copy, UFFDIO_COPY, copy) +DEFINE_MMAP_CHANGING_TEST(move, UFFDIO_MOVE, move) +DEFINE_MMAP_CHANGING_TEST(poison, UFFDIO_POISON, updated) +DEFINE_MMAP_CHANGING_TEST(continue, UFFDIO_CONTINUE, mapped) + +typedef enum { + /* We actually do not care about any state except UNINTERRUPTIBLE.. */ + THR_STATE_UNKNOWN = 0, + THR_STATE_UNINTERRUPTIBLE, +} thread_state; + +static void sleep_short(void) +{ + usleep(1000); +} + +static thread_state thread_state_get(pid_t tid) +{ + const char *header = "State:\t"; + char tmp[256], *p, c; + FILE *fp; + + snprintf(tmp, sizeof(tmp), "/proc/%d/status", tid); + fp = fopen(tmp, "r"); + + if (!fp) + return THR_STATE_UNKNOWN; + + while (fgets(tmp, sizeof(tmp), fp)) { + p = strstr(tmp, header); + if (p) { + /* For example, "State:\tD (disk sleep)" */ + c = *(p + sizeof(header) - 1); + return c == 'D' ? + THR_STATE_UNINTERRUPTIBLE : THR_STATE_UNKNOWN; + } + } + + return THR_STATE_UNKNOWN; +} + +static void thread_state_until(pid_t tid, thread_state state) +{ + thread_state s; + + do { + s = thread_state_get(tid); + sleep_short(); + } while (s != state); +} + +static void *uffd_mmap_changing_thread(void *opaque) +{ + volatile pid_t *pid = opaque; + int ret; + + /* Unfortunately, it's only fetch-able from the thread itself.. */ + assert(*pid == 0); + *pid = syscall(SYS_gettid); + + /* Inject an event, this will hang solid until the event read */ + ret = madvise(area_dst, page_size, MADV_REMOVE); + if (ret) + err("madvise(MADV_REMOVE) failed"); + + return NULL; +} + +static void uffd_consume_message(int fd) +{ + struct uffd_msg msg = { 0 }; + + while (uffd_read_msg(fd, &msg)); +} + +static void uffd_mmap_changing_test(uffd_test_args_t *targs) +{ + /* + * This stores the real PID (which can be different from how tid is + * defined..) for the child thread, 0 means not initialized. + */ + pid_t pid = 0; + pthread_t tid; + int ret; + + if (uffd_register(uffd, area_dst, nr_pages * page_size, + true, false, false)) + err("uffd_register() failed"); + + /* Create a thread to generate the racy event */ + ret = pthread_create(&tid, NULL, uffd_mmap_changing_thread, &pid); + if (ret) + err("pthread_create() failed"); + + /* + * Wait until the thread setup the pid. Use volatile to make sure + * it reads from RAM not regs. + */ + while (!(volatile pid_t)pid) + sleep_short(); + + /* Wait until the thread hangs at REMOVE event */ + thread_state_until(pid, THR_STATE_UNINTERRUPTIBLE); + + if (!uffdio_mmap_changing_test_copy(uffd)) + return; + + if (!uffdio_mmap_changing_test_zeropage(uffd)) + return; + + if (!uffdio_mmap_changing_test_move(uffd)) + return; + + if (!uffdio_mmap_changing_test_poison(uffd)) + return; + + if (!uffdio_mmap_changing_test_continue(uffd)) + return; + + /* + * All succeeded above! Recycle everything. Start by reading the + * event so as to kick the thread roll again.. + */ + uffd_consume_message(uffd); + + ret = pthread_join(tid, NULL); + assert(ret == 0); + + uffd_test_pass(); +} + static int prevent_hugepages(const char **errmsg) { /* This should be done before source area is populated */ @@ -1470,6 +1646,32 @@ uffd_test_case_t uffd_tests[] = { .mem_targets = MEM_ALL, .uffd_feature_required = UFFD_FEATURE_POISON, }, + { + .name = "mmap-changing", + .uffd_fn = uffd_mmap_changing_test, + /* + * There's no point running this test over all mem types as + * they share the same code paths. + * + * Choose shmem for simplicity, because (1) shmem supports + * MINOR mode to cover UFFDIO_CONTINUE, and (2) shmem is + * almost always available (unlike hugetlb). Here we + * abused SHMEM for UFFDIO_MOVE, but the test we want to + * cover doesn't yet need the correct memory type.. + */ + .mem_targets = MEM_SHMEM, + /* + * Any UFFD_FEATURE_EVENT_* should work to trigger the + * race logically, but choose the simplest (REMOVE). + * + * Meanwhile, since we'll cover quite a few new ioctl()s + * (CONTINUE, POISON, MOVE), skip this test for old kernels + * by choosing all of them. + */ + .uffd_feature_required = UFFD_FEATURE_EVENT_REMOVE | + UFFD_FEATURE_MOVE | UFFD_FEATURE_POISON | + UFFD_FEATURE_MINOR_SHMEM, + }, }; static void usage(const char *prog) |