diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c index ea598173c5e6..2f2855d8f595 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -77,6 +77,8 @@ static int test_type; #define ALARM_INTERVAL_SECS 10 static volatile bool test_uffdio_copy_eexist = true; static volatile bool test_uffdio_zeropage_eexist = true; +/* Whether to test uffd minor faults */ +static bool test_uffdio_minor = false; static bool map_shared; static int huge_fd; @@ -91,6 +93,7 @@ pthread_attr_t attr; struct uffd_stats { int cpu; unsigned long missing_faults; + unsigned long minor_faults; }; /* pthread_mutex_t starts at page offset 0 */ @@ -140,21 +143,26 @@ static void uffd_stats_reset(struct uffd_stats *uffd_stats, for (i = 0; i < n_cpus; i++) { uffd_stats[i].cpu = i; uffd_stats[i].missing_faults = 0; + uffd_stats[i].minor_faults = 0; } } static void uffd_stats_report(struct uffd_stats *stats, int n_cpus) { int i; - unsigned long long miss_total = 0; + unsigned long long miss_total = 0, minor_total = 0; for (i = 0; i < n_cpus; i++) { miss_total += stats[i].missing_faults; + minor_total += stats[i].minor_faults; } printf("userfaults: %llu missing (", miss_total); for (i = 0; i < n_cpus; i++) printf("%lu+", stats[i].missing_faults); + printf("\b), %llu minor (", minor_total); + for (i = 0; i < n_cpus; i++) + printf("%lu+", stats[i].minor_faults); printf("\b)\n"); } @@ -299,7 +307,7 @@ static struct uffd_test_ops shmem_uffd_test_ops = { }; static struct uffd_test_ops hugetlb_uffd_test_ops = { - .expected_ioctls = UFFD_API_RANGE_IOCTLS_BASIC, + .expected_ioctls = UFFD_API_RANGE_IOCTLS_BASIC & ~(1 << _UFFDIO_CONTINUE), .allocate_area = hugetlb_allocate_area, .release_pages = hugetlb_release_pages, .alias_mapping = hugetlb_alias_mapping, @@ -316,6 +324,22 @@ static int my_bcmp(char *str1, char *str2, size_t n) return 0; } +static void continue_range(int ufd, __u64 start, __u64 len) +{ + struct uffdio_continue req; + + req.range.start = start; + req.range.len = len; + req.mode = 0; + + if (ioctl(ufd, UFFDIO_CONTINUE, &req)) { + fprintf(stderr, + "UFFDIO_CONTINUE failed for address 0x%" PRIx64 "\n", + (uint64_t)start); + exit(1); + } +} + static void *locking_thread(void *arg) { unsigned long cpu = (unsigned long) arg; @@ -454,14 +478,42 @@ static void uffd_handle_page_fault(struct uffd_msg *msg, fprintf(stderr, "unexpected msg event %u\n", msg->event), exit(1); - if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE) - fprintf(stderr, "unexpected write fault\n"), exit(1); + if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_MINOR) { + uint8_t *area; + int b; - offset = (char *)(unsigned long)msg->arg.pagefault.address - area_dst; - offset &= ~(page_size-1); + /* + * Minor page faults + * + * To prove we can modify the original range for testing + * purposes, we're going to bit flip this range before + * continuing. + * + * Note that this requires all minor page fault tests operate on + * area_dst (non-UFFD-registered) and area_dst_alias + * (UFFD-registered). + */ - if (copy_page(uffd, offset)) - stats->missing_faults++; + area = (uint8_t *)(area_dst + + ((char *)msg->arg.pagefault.address - + area_dst_alias)); + for (b = 0; b < page_size; ++b) + area[b] = ~area[b]; + continue_range(uffd, msg->arg.pagefault.address, page_size); + stats->minor_faults++; + } else { + /* Missing page faults */ + if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE) { + fprintf(stderr, "unexpected write fault\n"); + exit(1); + } + + offset = (char *)(unsigned long)msg->arg.pagefault.address - area_dst; + offset &= ~(page_size-1); + + if (copy_page(uffd, offset)) + stats->missing_faults++; + } } static void *uffd_poll_thread(void *arg) @@ -628,7 +680,7 @@ static int stress(struct uffd_stats *uffd_stats) return 0; } -static int userfaultfd_open(int features) +static int userfaultfd_open_ext(uint64_t *features) { struct uffdio_api uffdio_api; @@ -641,7 +693,7 @@ static int userfaultfd_open(int features) uffd_flags = fcntl(uffd, F_GETFD, NULL); uffdio_api.api = UFFD_API; - uffdio_api.features = features; + uffdio_api.features = *features; if (ioctl(uffd, UFFDIO_API, &uffdio_api)) { fprintf(stderr, "UFFDIO_API\n"); return 1; @@ -651,9 +703,15 @@ static int userfaultfd_open(int features) return 1; } + *features = uffdio_api.features; return 0; } +static int userfaultfd_open(uint64_t features) +{ + return userfaultfd_open_ext(&features); +} + sigjmp_buf jbuf, *sigbuf; static void sighndl(int sig, siginfo_t *siginfo, void *ptr) @@ -925,7 +983,7 @@ static int userfaultfd_events_test(void) perror("fork"), exit(1); if (!pid) - return faulting_process(0); + exit(faulting_process(0)); waitpid(pid, &err, 0); if (err) @@ -1011,6 +1069,102 @@ static int userfaultfd_sig_test(void) return userfaults != 0; } +static int userfaultfd_minor_test(void) +{ + struct uffdio_register uffdio_register; + unsigned long expected_ioctls; + unsigned long p; + pthread_t uffd_mon; + uint8_t expected_byte; + void *expected_page; + char c; + struct uffd_stats stats = { 0 }; + uint64_t features = UFFD_FEATURE_MINOR_HUGETLBFS; + + if (!test_uffdio_minor) + return 0; + + printf("testing minor faults: "); + fflush(stdout); + + if (uffd_test_ops->release_pages(area_dst)) + return 1; + + if (userfaultfd_open_ext(&features)) + return 1; + /* If kernel reports the feature isn't supported, skip the test. */ + if (!(features & UFFD_FEATURE_MINOR_HUGETLBFS)) { + printf("skipping test due to lack of feature support\n"); + fflush(stdout); + return 0; + } + + uffdio_register.range.start = (unsigned long)area_dst_alias; + uffdio_register.range.len = nr_pages * page_size; + uffdio_register.mode = UFFDIO_REGISTER_MODE_MINOR; + if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register)) { + fprintf(stderr, "register failure\n"); + exit(1); + } + + expected_ioctls = uffd_test_ops->expected_ioctls; + expected_ioctls |= 1 << _UFFDIO_CONTINUE; + if ((uffdio_register.ioctls & expected_ioctls) != expected_ioctls) { + fprintf(stderr, "unexpected missing ioctl(s)\n"); + exit(1); + } + + /* + * After registering with UFFD, populate the non-UFFD-registered side of + * the shared mapping. This should *not* trigger any UFFD minor faults. + */ + for (p = 0; p < nr_pages; ++p) { + memset(area_dst + (p * page_size), p % ((uint8_t)-1), + page_size); + } + + if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, &stats)) { + perror("uffd_poll_thread create"); + exit(1); + } + + /* + * Read each of the pages back using the UFFD-registered mapping. We + * expect that the first time we touch a page, it will result in a minor + * fault. uffd_poll_thread will resolve the fault by bit-flipping the + * page's contents, and then issuing a CONTINUE ioctl. + */ + + if (posix_memalign(&expected_page, page_size, page_size)) { + fprintf(stderr, "out of memory\n"); + return 1; + } + + for (p = 0; p < nr_pages; ++p) { + expected_byte = ~((uint8_t)(p % ((uint8_t)-1))); + memset(expected_page, expected_byte, page_size); + if (my_bcmp(expected_page, area_dst_alias + (p * page_size), + page_size)) { + fprintf(stderr, + "unexpected page contents after minor fault\n"); + exit(1); + } + } + + if (write(pipefd[1], &c, sizeof(c)) != sizeof(c)) { + perror("pipe write"); + exit(1); + } + if (pthread_join(uffd_mon, NULL)) + return 1; + + close(uffd); + + uffd_stats_report(&stats, 1); + + return stats.missing_faults != 0 || stats.minor_faults != nr_pages; +} + static int userfaultfd_stress(void) { void *area; @@ -1200,7 +1354,7 @@ static int userfaultfd_stress(void) close(uffd); return userfaultfd_zeropage_test() || userfaultfd_sig_test() - || userfaultfd_events_test(); + || userfaultfd_events_test() || userfaultfd_minor_test(); } /* @@ -1239,6 +1393,8 @@ static void set_test_type(const char *type) map_shared = true; test_type = TEST_HUGETLB; uffd_test_ops = &hugetlb_uffd_test_ops; + /* Minor faults require shared hugetlb; only enable here. */ + test_uffdio_minor = true; } else if (!strcmp(type, "shmem")) { map_shared = true; test_type = TEST_SHMEM;