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-rw-r--r--tools/testing/selftests/mm/uffd-stress.c521
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diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c
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+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Stress userfaultfd syscall.
+ *
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * This test allocates two virtual areas and bounces the physical
+ * memory across the two virtual areas (from area_src to area_dst)
+ * using userfaultfd.
+ *
+ * There are three threads running per CPU:
+ *
+ * 1) one per-CPU thread takes a per-page pthread_mutex in a random
+ * page of the area_dst (while the physical page may still be in
+ * area_src), and increments a per-page counter in the same page,
+ * and checks its value against a verification region.
+ *
+ * 2) another per-CPU thread handles the userfaults generated by
+ * thread 1 above. userfaultfd blocking reads or poll() modes are
+ * exercised interleaved.
+ *
+ * 3) one last per-CPU thread transfers the memory in the background
+ * at maximum bandwidth (if not already transferred by thread
+ * 2). Each cpu thread takes cares of transferring a portion of the
+ * area.
+ *
+ * When all threads of type 3 completed the transfer, one bounce is
+ * complete. area_src and area_dst are then swapped. All threads are
+ * respawned and so the bounce is immediately restarted in the
+ * opposite direction.
+ *
+ * per-CPU threads 1 by triggering userfaults inside
+ * pthread_mutex_lock will also verify the atomicity of the memory
+ * transfer (UFFDIO_COPY).
+ */
+
+#include "uffd-common.h"
+
+uint64_t features;
+#ifdef __NR_userfaultfd
+
+#define BOUNCE_RANDOM (1<<0)
+#define BOUNCE_RACINGFAULTS (1<<1)
+#define BOUNCE_VERIFY (1<<2)
+#define BOUNCE_POLL (1<<3)
+static int bounces;
+/* defined globally for this particular test as the sigalrm handler
+ * depends on test_uffdio_*_eexist.
+ * XXX: define gopts in main() when we figure out a way to deal with
+ * test_uffdio_*_eexist.
+ */
+static uffd_global_test_opts_t *gopts;
+
+/* exercise the test_uffdio_*_eexist every ALARM_INTERVAL_SECS */
+#define ALARM_INTERVAL_SECS 10
+static char *zeropage;
+pthread_attr_t attr;
+
+#define swap(a, b) \
+ do { __auto_type __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
+
+const char *examples =
+ "# Run anonymous memory test on 100MiB region with 99999 bounces:\n"
+ "./uffd-stress anon 100 99999\n\n"
+ "# Run share memory test on 1GiB region with 99 bounces:\n"
+ "./uffd-stress shmem 1000 99\n\n"
+ "# Run hugetlb memory test on 256MiB region with 50 bounces:\n"
+ "./uffd-stress hugetlb 256 50\n\n"
+ "# Run the same hugetlb test but using private file:\n"
+ "./uffd-stress hugetlb-private 256 50\n\n"
+ "# 10MiB-~6GiB 999 bounces anonymous test, "
+ "continue forever unless an error triggers\n"
+ "while ./uffd-stress anon $[RANDOM % 6000 + 10] 999; do true; done\n\n";
+
+static void usage(void)
+{
+ fprintf(stderr, "\nUsage: ./uffd-stress <test type> <MiB> <bounces>\n\n");
+ fprintf(stderr, "Supported <test type>: anon, hugetlb, "
+ "hugetlb-private, shmem, shmem-private\n\n");
+ fprintf(stderr, "Examples:\n\n");
+ fprintf(stderr, "%s", examples);
+ exit(1);
+}
+
+static void uffd_stats_reset(uffd_global_test_opts_t *gopts, struct uffd_args *args,
+ unsigned long n_cpus)
+{
+ int i;
+
+ for (i = 0; i < n_cpus; i++) {
+ args[i].cpu = i;
+ args[i].apply_wp = gopts->test_uffdio_wp;
+ args[i].missing_faults = 0;
+ args[i].wp_faults = 0;
+ args[i].minor_faults = 0;
+ args[i].gopts = gopts;
+ }
+}
+
+static void *locking_thread(void *arg)
+{
+ struct uffd_args *args = (struct uffd_args *) arg;
+ uffd_global_test_opts_t *gopts = args->gopts;
+ unsigned long cpu = (unsigned long) args->cpu;
+ unsigned long page_nr;
+ unsigned long long count;
+
+ if (!(bounces & BOUNCE_RANDOM)) {
+ page_nr = -bounces;
+ if (!(bounces & BOUNCE_RACINGFAULTS))
+ page_nr += cpu * gopts->nr_pages_per_cpu;
+ }
+
+ while (!gopts->finished) {
+ if (bounces & BOUNCE_RANDOM) {
+ if (getrandom(&page_nr, sizeof(page_nr), 0) != sizeof(page_nr))
+ err("getrandom failed");
+ } else
+ page_nr += 1;
+ page_nr %= gopts->nr_pages;
+ pthread_mutex_lock(area_mutex(gopts->area_dst, page_nr, gopts));
+ count = *area_count(gopts->area_dst, page_nr, gopts);
+ if (count != gopts->count_verify[page_nr])
+ err("page_nr %lu memory corruption %llu %llu",
+ page_nr, count, gopts->count_verify[page_nr]);
+ count++;
+ *area_count(gopts->area_dst, page_nr, gopts) = gopts->count_verify[page_nr] = count;
+ pthread_mutex_unlock(area_mutex(gopts->area_dst, page_nr, gopts));
+ }
+
+ return NULL;
+}
+
+static int copy_page_retry(uffd_global_test_opts_t *gopts, unsigned long offset)
+{
+ return __copy_page(gopts, offset, true, gopts->test_uffdio_wp);
+}
+
+pthread_mutex_t uffd_read_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static void *uffd_read_thread(void *arg)
+{
+ struct uffd_args *args = (struct uffd_args *)arg;
+ uffd_global_test_opts_t *gopts = args->gopts;
+ struct uffd_msg msg;
+
+ pthread_mutex_unlock(&uffd_read_mutex);
+ /* from here cancellation is ok */
+
+ for (;;) {
+ if (uffd_read_msg(gopts, &msg))
+ continue;
+ uffd_handle_page_fault(gopts, &msg, args);
+ }
+
+ return NULL;
+}
+
+static void *background_thread(void *arg)
+{
+ struct uffd_args *args = (struct uffd_args *) arg;
+ uffd_global_test_opts_t *gopts = args->gopts;
+ unsigned long cpu = (unsigned long) args->cpu;
+ unsigned long page_nr, start_nr, mid_nr, end_nr;
+
+ start_nr = cpu * gopts->nr_pages_per_cpu;
+ end_nr = (cpu+1) * gopts->nr_pages_per_cpu;
+ mid_nr = (start_nr + end_nr) / 2;
+
+ /* Copy the first half of the pages */
+ for (page_nr = start_nr; page_nr < mid_nr; page_nr++)
+ copy_page_retry(gopts, page_nr * gopts->page_size);
+
+ /*
+ * If we need to test uffd-wp, set it up now. Then we'll have
+ * at least the first half of the pages mapped already which
+ * can be write-protected for testing
+ */
+ if (gopts->test_uffdio_wp)
+ wp_range(gopts->uffd, (unsigned long)gopts->area_dst + start_nr * gopts->page_size,
+ gopts->nr_pages_per_cpu * gopts->page_size, true);
+
+ /*
+ * Continue the 2nd half of the page copying, handling write
+ * protection faults if any
+ */
+ for (page_nr = mid_nr; page_nr < end_nr; page_nr++)
+ copy_page_retry(gopts, page_nr * gopts->page_size);
+
+ return NULL;
+}
+
+static int stress(struct uffd_args *args)
+{
+ unsigned long cpu;
+ uffd_global_test_opts_t *gopts = args->gopts;
+ pthread_t locking_threads[gopts->nr_parallel];
+ pthread_t uffd_threads[gopts->nr_parallel];
+ pthread_t background_threads[gopts->nr_parallel];
+
+ gopts->finished = 0;
+ for (cpu = 0; cpu < gopts->nr_parallel; cpu++) {
+ if (pthread_create(&locking_threads[cpu], &attr,
+ locking_thread, (void *)&args[cpu]))
+ return 1;
+ if (bounces & BOUNCE_POLL) {
+ if (pthread_create(&uffd_threads[cpu],
+ &attr,
+ uffd_poll_thread,
+ (void *) &args[cpu]))
+ err("uffd_poll_thread create");
+ } else {
+ if (pthread_create(&uffd_threads[cpu], &attr,
+ uffd_read_thread,
+ (void *)&args[cpu]))
+ return 1;
+ pthread_mutex_lock(&uffd_read_mutex);
+ }
+ if (pthread_create(&background_threads[cpu], &attr,
+ background_thread, (void *)&args[cpu]))
+ return 1;
+ }
+ for (cpu = 0; cpu < gopts->nr_parallel; cpu++)
+ if (pthread_join(background_threads[cpu], NULL))
+ return 1;
+
+ /*
+ * Be strict and immediately zap area_src, the whole area has
+ * been transferred already by the background treads. The
+ * area_src could then be faulted in a racy way by still
+ * running uffdio_threads reading zeropages after we zapped
+ * area_src (but they're guaranteed to get -EEXIST from
+ * UFFDIO_COPY without writing zero pages into area_dst
+ * because the background threads already completed).
+ */
+ uffd_test_ops->release_pages(gopts, gopts->area_src);
+
+ gopts->finished = 1;
+ for (cpu = 0; cpu < gopts->nr_parallel; cpu++)
+ if (pthread_join(locking_threads[cpu], NULL))
+ return 1;
+
+ for (cpu = 0; cpu < gopts->nr_parallel; cpu++) {
+ char c = '\0';
+ if (bounces & BOUNCE_POLL) {
+ if (write(gopts->pipefd[cpu*2+1], &c, 1) != 1)
+ err("pipefd write error");
+ if (pthread_join(uffd_threads[cpu],
+ (void *)&args[cpu]))
+ return 1;
+ } else {
+ if (pthread_cancel(uffd_threads[cpu]))
+ return 1;
+ if (pthread_join(uffd_threads[cpu], NULL))
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+static int userfaultfd_stress(uffd_global_test_opts_t *gopts)
+{
+ void *area;
+ unsigned long nr;
+ struct uffd_args args[gopts->nr_parallel];
+ uint64_t mem_size = gopts->nr_pages * gopts->page_size;
+ int flags = 0;
+
+ memset(args, 0, sizeof(struct uffd_args) * gopts->nr_parallel);
+
+ if (features & UFFD_FEATURE_WP_UNPOPULATED && gopts->test_type == TEST_ANON)
+ flags = UFFD_FEATURE_WP_UNPOPULATED;
+
+ if (uffd_test_ctx_init(gopts, flags, NULL))
+ err("context init failed");
+
+ if (posix_memalign(&area, gopts->page_size, gopts->page_size))
+ err("out of memory");
+ zeropage = area;
+ bzero(zeropage, gopts->page_size);
+
+ pthread_mutex_lock(&uffd_read_mutex);
+
+ pthread_attr_init(&attr);
+ pthread_attr_setstacksize(&attr, 16*1024*1024);
+
+ while (bounces--) {
+ printf("bounces: %d, mode:", bounces);
+ if (bounces & BOUNCE_RANDOM)
+ printf(" rnd");
+ if (bounces & BOUNCE_RACINGFAULTS)
+ printf(" racing");
+ if (bounces & BOUNCE_VERIFY)
+ printf(" ver");
+ if (bounces & BOUNCE_POLL)
+ printf(" poll");
+ else
+ printf(" read");
+ printf(", ");
+ fflush(stdout);
+
+ if (bounces & BOUNCE_POLL)
+ fcntl(gopts->uffd, F_SETFL, gopts->uffd_flags | O_NONBLOCK);
+ else
+ fcntl(gopts->uffd, F_SETFL, gopts->uffd_flags & ~O_NONBLOCK);
+
+ /* register */
+ if (uffd_register(gopts->uffd, gopts->area_dst, mem_size,
+ true, gopts->test_uffdio_wp, false))
+ err("register failure");
+
+ if (gopts->area_dst_alias) {
+ if (uffd_register(gopts->uffd, gopts->area_dst_alias, mem_size,
+ true, gopts->test_uffdio_wp, false))
+ err("register failure alias");
+ }
+
+ /*
+ * The madvise done previously isn't enough: some
+ * uffd_thread could have read userfaults (one of
+ * those already resolved by the background thread)
+ * and it may be in the process of calling
+ * UFFDIO_COPY. UFFDIO_COPY will read the zapped
+ * area_src and it would map a zero page in it (of
+ * course such a UFFDIO_COPY is perfectly safe as it'd
+ * return -EEXIST). The problem comes at the next
+ * bounce though: that racing UFFDIO_COPY would
+ * generate zeropages in the area_src, so invalidating
+ * the previous MADV_DONTNEED. Without this additional
+ * MADV_DONTNEED those zeropages leftovers in the
+ * area_src would lead to -EEXIST failure during the
+ * next bounce, effectively leaving a zeropage in the
+ * area_dst.
+ *
+ * Try to comment this out madvise to see the memory
+ * corruption being caught pretty quick.
+ *
+ * khugepaged is also inhibited to collapse THP after
+ * MADV_DONTNEED only after the UFFDIO_REGISTER, so it's
+ * required to MADV_DONTNEED here.
+ */
+ uffd_test_ops->release_pages(gopts, gopts->area_dst);
+
+ uffd_stats_reset(gopts, args, gopts->nr_parallel);
+
+ /* bounce pass */
+ if (stress(args)) {
+ uffd_test_ctx_clear(gopts);
+ return 1;
+ }
+
+ /* Clear all the write protections if there is any */
+ if (gopts->test_uffdio_wp)
+ wp_range(gopts->uffd, (unsigned long)gopts->area_dst,
+ gopts->nr_pages * gopts->page_size, false);
+
+ /* unregister */
+ if (uffd_unregister(gopts->uffd, gopts->area_dst, mem_size))
+ err("unregister failure");
+ if (gopts->area_dst_alias) {
+ if (uffd_unregister(gopts->uffd, gopts->area_dst_alias, mem_size))
+ err("unregister failure alias");
+ }
+
+ /* verification */
+ if (bounces & BOUNCE_VERIFY)
+ for (nr = 0; nr < gopts->nr_pages; nr++)
+ if (*area_count(gopts->area_dst, nr, gopts) !=
+ gopts->count_verify[nr])
+ err("error area_count %llu %llu %lu\n",
+ *area_count(gopts->area_src, nr, gopts),
+ gopts->count_verify[nr], nr);
+
+ /* prepare next bounce */
+ swap(gopts->area_src, gopts->area_dst);
+
+ swap(gopts->area_src_alias, gopts->area_dst_alias);
+
+ uffd_stats_report(args, gopts->nr_parallel);
+ }
+ uffd_test_ctx_clear(gopts);
+
+ return 0;
+}
+
+static void set_test_type(uffd_global_test_opts_t *gopts, const char *type)
+{
+ if (!strcmp(type, "anon")) {
+ gopts->test_type = TEST_ANON;
+ uffd_test_ops = &anon_uffd_test_ops;
+ } else if (!strcmp(type, "hugetlb")) {
+ gopts->test_type = TEST_HUGETLB;
+ uffd_test_ops = &hugetlb_uffd_test_ops;
+ gopts->map_shared = true;
+ } else if (!strcmp(type, "hugetlb-private")) {
+ gopts->test_type = TEST_HUGETLB;
+ uffd_test_ops = &hugetlb_uffd_test_ops;
+ } else if (!strcmp(type, "shmem")) {
+ gopts->map_shared = true;
+ gopts->test_type = TEST_SHMEM;
+ uffd_test_ops = &shmem_uffd_test_ops;
+ } else if (!strcmp(type, "shmem-private")) {
+ gopts->test_type = TEST_SHMEM;
+ uffd_test_ops = &shmem_uffd_test_ops;
+ }
+}
+
+static void parse_test_type_arg(uffd_global_test_opts_t *gopts, const char *raw_type)
+{
+ set_test_type(gopts, raw_type);
+
+ if (!gopts->test_type)
+ err("failed to parse test type argument: '%s'", raw_type);
+
+ if (gopts->test_type == TEST_HUGETLB)
+ gopts->page_size = default_huge_page_size();
+ else
+ gopts->page_size = sysconf(_SC_PAGE_SIZE);
+
+ if (!gopts->page_size)
+ err("Unable to determine page size");
+ if ((unsigned long) area_count(NULL, 0, gopts) + sizeof(unsigned long long) * 2
+ > gopts->page_size)
+ err("Impossible to run this test");
+
+ /*
+ * Whether we can test certain features depends not just on test type,
+ * but also on whether or not this particular kernel supports the
+ * feature.
+ */
+
+ if (uffd_get_features(&features) && errno == ENOENT)
+ ksft_exit_skip("failed to get available features (%d)\n", errno);
+
+ gopts->test_uffdio_wp = gopts->test_uffdio_wp &&
+ (features & UFFD_FEATURE_PAGEFAULT_FLAG_WP);
+
+ if (gopts->test_type != TEST_ANON && !(features & UFFD_FEATURE_WP_HUGETLBFS_SHMEM))
+ gopts->test_uffdio_wp = false;
+
+ close(gopts->uffd);
+ gopts->uffd = -1;
+}
+
+static void sigalrm(int sig)
+{
+ if (sig != SIGALRM)
+ abort();
+ gopts->test_uffdio_copy_eexist = true;
+ alarm(ALARM_INTERVAL_SECS);
+}
+
+int main(int argc, char **argv)
+{
+ unsigned long nr_cpus;
+ size_t bytes;
+
+ gopts = (uffd_global_test_opts_t *) malloc(sizeof(uffd_global_test_opts_t));
+
+ if (argc < 4)
+ usage();
+
+ if (signal(SIGALRM, sigalrm) == SIG_ERR)
+ err("failed to arm SIGALRM");
+ alarm(ALARM_INTERVAL_SECS);
+
+ parse_test_type_arg(gopts, argv[1]);
+ bytes = atol(argv[2]) * 1024 * 1024;
+
+ nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
+ if (nr_cpus > 32) {
+ /* Don't let calculation below go to zero. */
+ ksft_print_msg("_SC_NPROCESSORS_ONLN (%lu) too large, capping nr_threads to 32\n",
+ nr_cpus);
+ gopts->nr_parallel = 32;
+ } else {
+ gopts->nr_parallel = nr_cpus;
+ }
+
+ /*
+ * src and dst each require bytes / page_size number of hugepages.
+ * Ensure nr_parallel - 1 hugepages on top of that to account
+ * for racy extra reservation of hugepages.
+ */
+ if (gopts->test_type == TEST_HUGETLB &&
+ get_free_hugepages() < 2 * (bytes / gopts->page_size) + gopts->nr_parallel - 1) {
+ printf("skip: Skipping userfaultfd... not enough hugepages\n");
+ return KSFT_SKIP;
+ }
+
+ gopts->nr_pages_per_cpu = bytes / gopts->page_size / gopts->nr_parallel;
+ if (!gopts->nr_pages_per_cpu) {
+ _err("pages_per_cpu = 0, cannot test (%lu / %lu / %lu)",
+ bytes, gopts->page_size, gopts->nr_parallel);
+ usage();
+ }
+
+ bounces = atoi(argv[3]);
+ if (bounces <= 0) {
+ _err("invalid bounces");
+ usage();
+ }
+ gopts->nr_pages = gopts->nr_pages_per_cpu * gopts->nr_parallel;
+
+ printf("nr_pages: %lu, nr_pages_per_cpu: %lu\n",
+ gopts->nr_pages, gopts->nr_pages_per_cpu);
+ return userfaultfd_stress(gopts);
+}
+
+#else /* __NR_userfaultfd */
+
+#warning "missing __NR_userfaultfd definition"
+
+int main(void)
+{
+ printf("skip: Skipping userfaultfd test (missing __NR_userfaultfd)\n");
+ return KSFT_SKIP;
+}
+
+#endif /* __NR_userfaultfd */
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