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Diffstat (limited to 'tools/testing/selftests/vm/userfaultfd.c')
-rw-r--r--tools/testing/selftests/vm/userfaultfd.c164
1 files changed, 158 insertions, 6 deletions
diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
index 92b8ec423201..f5ab5e0312e7 100644
--- a/tools/testing/selftests/vm/userfaultfd.c
+++ b/tools/testing/selftests/vm/userfaultfd.c
@@ -81,6 +81,8 @@ static volatile bool test_uffdio_copy_eexist = true;
static volatile bool test_uffdio_zeropage_eexist = true;
/* Whether to test uffd write-protection */
static bool test_uffdio_wp = false;
+/* Whether to test uffd minor faults */
+static bool test_uffdio_minor = false;
static bool map_shared;
static int huge_fd;
@@ -96,6 +98,7 @@ struct uffd_stats {
int cpu;
unsigned long missing_faults;
unsigned long wp_faults;
+ unsigned long minor_faults;
};
/* pthread_mutex_t starts at page offset 0 */
@@ -153,17 +156,19 @@ static void uffd_stats_reset(struct uffd_stats *uffd_stats,
uffd_stats[i].cpu = i;
uffd_stats[i].missing_faults = 0;
uffd_stats[i].wp_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, wp_total = 0;
+ unsigned long long miss_total = 0, wp_total = 0, minor_total = 0;
for (i = 0; i < n_cpus; i++) {
miss_total += stats[i].missing_faults;
wp_total += stats[i].wp_faults;
+ minor_total += stats[i].minor_faults;
}
printf("userfaults: %llu missing (", miss_total);
@@ -172,6 +177,9 @@ static void uffd_stats_report(struct uffd_stats *stats, int n_cpus)
printf("\b), %llu wp (", wp_total);
for (i = 0; i < n_cpus; i++)
printf("%lu+", stats[i].wp_faults);
+ printf("\b), %llu minor (", minor_total);
+ for (i = 0; i < n_cpus; i++)
+ printf("%lu+", stats[i].minor_faults);
printf("\b)\n");
}
@@ -328,7 +336,7 @@ 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,
@@ -362,6 +370,22 @@ static void wp_range(int ufd, __u64 start, __u64 len, bool wp)
}
}
+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;
@@ -569,8 +593,32 @@ static void uffd_handle_page_fault(struct uffd_msg *msg,
}
if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WP) {
+ /* Write protect page faults */
wp_range(uffd, msg->arg.pagefault.address, page_size, false);
stats->wp_faults++;
+ } else if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_MINOR) {
+ uint8_t *area;
+ int b;
+
+ /*
+ * 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).
+ */
+
+ 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 (bounces & BOUNCE_VERIFY &&
@@ -779,7 +827,7 @@ 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;
@@ -792,7 +840,7 @@ 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 failed.\nPlease make sure to "
"run with either root or ptrace capability.\n");
@@ -804,9 +852,15 @@ 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)
@@ -1112,7 +1166,7 @@ static int userfaultfd_events_test(void)
}
if (!pid)
- return faulting_process(0);
+ exit(faulting_process(0));
waitpid(pid, &err, 0);
if (err) {
@@ -1215,6 +1269,102 @@ 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;
@@ -1413,7 +1563,7 @@ static int userfaultfd_stress(void)
close(uffd);
return userfaultfd_zeropage_test() || userfaultfd_sig_test()
- || userfaultfd_events_test();
+ || userfaultfd_events_test() || userfaultfd_minor_test();
}
/*
@@ -1454,6 +1604,8 @@ 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;