// 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 */