v4.19.13 snapshot.
diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
new file mode 100644
index 0000000..7b8171e
--- /dev/null
+++ b/tools/testing/selftests/vm/userfaultfd.c
@@ -0,0 +1,1330 @@
+/*
+ * Stress userfaultfd syscall.
+ *
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ *
+ * 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).
+ *
+ * The program takes two parameters: the amounts of physical memory in
+ * megabytes (MiB) of the area and the number of bounces to execute.
+ *
+ * # 100MiB 99999 bounces
+ * ./userfaultfd 100 99999
+ *
+ * # 1GiB 99 bounces
+ * ./userfaultfd 1000 99
+ *
+ * # 10MiB-~6GiB 999 bounces, continue forever unless an error triggers
+ * while ./userfaultfd $[RANDOM % 6000 + 10] 999; do true; done
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <time.h>
+#include <signal.h>
+#include <poll.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include <pthread.h>
+#include <linux/userfaultfd.h>
+#include <setjmp.h>
+#include <stdbool.h>
+
+#include "../kselftest.h"
+
+#ifdef __NR_userfaultfd
+
+static unsigned long nr_cpus, nr_pages, nr_pages_per_cpu, page_size;
+
+#define BOUNCE_RANDOM (1<<0)
+#define BOUNCE_RACINGFAULTS (1<<1)
+#define BOUNCE_VERIFY (1<<2)
+#define BOUNCE_POLL (1<<3)
+static int bounces;
+
+#define TEST_ANON 1
+#define TEST_HUGETLB 2
+#define TEST_SHMEM 3
+static int test_type;
+
+/* exercise the test_uffdio_*_eexist every ALARM_INTERVAL_SECS */
+#define ALARM_INTERVAL_SECS 10
+static volatile bool test_uffdio_copy_eexist = true;
+static volatile bool test_uffdio_zeropage_eexist = true;
+
+static bool map_shared;
+static int huge_fd;
+static char *huge_fd_off0;
+static unsigned long long *count_verify;
+static int uffd, uffd_flags, finished, *pipefd;
+static char *area_src, *area_src_alias, *area_dst, *area_dst_alias;
+static char *zeropage;
+pthread_attr_t attr;
+
+/* pthread_mutex_t starts at page offset 0 */
+#define area_mutex(___area, ___nr) \
+ ((pthread_mutex_t *) ((___area) + (___nr)*page_size))
+/*
+ * count is placed in the page after pthread_mutex_t naturally aligned
+ * to avoid non alignment faults on non-x86 archs.
+ */
+#define area_count(___area, ___nr) \
+ ((volatile unsigned long long *) ((unsigned long) \
+ ((___area) + (___nr)*page_size + \
+ sizeof(pthread_mutex_t) + \
+ sizeof(unsigned long long) - 1) & \
+ ~(unsigned long)(sizeof(unsigned long long) \
+ - 1)))
+
+static int anon_release_pages(char *rel_area)
+{
+ int ret = 0;
+
+ if (madvise(rel_area, nr_pages * page_size, MADV_DONTNEED)) {
+ perror("madvise");
+ ret = 1;
+ }
+
+ return ret;
+}
+
+static void anon_allocate_area(void **alloc_area)
+{
+ if (posix_memalign(alloc_area, page_size, nr_pages * page_size)) {
+ fprintf(stderr, "out of memory\n");
+ *alloc_area = NULL;
+ }
+}
+
+static void noop_alias_mapping(__u64 *start, size_t len, unsigned long offset)
+{
+}
+
+/* HugeTLB memory */
+static int hugetlb_release_pages(char *rel_area)
+{
+ int ret = 0;
+
+ if (fallocate(huge_fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+ rel_area == huge_fd_off0 ? 0 :
+ nr_pages * page_size,
+ nr_pages * page_size)) {
+ perror("fallocate");
+ ret = 1;
+ }
+
+ return ret;
+}
+
+
+static void hugetlb_allocate_area(void **alloc_area)
+{
+ void *area_alias = NULL;
+ char **alloc_area_alias;
+ *alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
+ (map_shared ? MAP_SHARED : MAP_PRIVATE) |
+ MAP_HUGETLB,
+ huge_fd, *alloc_area == area_src ? 0 :
+ nr_pages * page_size);
+ if (*alloc_area == MAP_FAILED) {
+ fprintf(stderr, "mmap of hugetlbfs file failed\n");
+ *alloc_area = NULL;
+ }
+
+ if (map_shared) {
+ area_alias = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
+ MAP_SHARED | MAP_HUGETLB,
+ huge_fd, *alloc_area == area_src ? 0 :
+ nr_pages * page_size);
+ if (area_alias == MAP_FAILED) {
+ if (munmap(*alloc_area, nr_pages * page_size) < 0)
+ perror("hugetlb munmap"), exit(1);
+ *alloc_area = NULL;
+ return;
+ }
+ }
+ if (*alloc_area == area_src) {
+ huge_fd_off0 = *alloc_area;
+ alloc_area_alias = &area_src_alias;
+ } else {
+ alloc_area_alias = &area_dst_alias;
+ }
+ if (area_alias)
+ *alloc_area_alias = area_alias;
+}
+
+static void hugetlb_alias_mapping(__u64 *start, size_t len, unsigned long offset)
+{
+ if (!map_shared)
+ return;
+ /*
+ * We can't zap just the pagetable with hugetlbfs because
+ * MADV_DONTEED won't work. So exercise -EEXIST on a alias
+ * mapping where the pagetables are not established initially,
+ * this way we'll exercise the -EEXEC at the fs level.
+ */
+ *start = (unsigned long) area_dst_alias + offset;
+}
+
+/* Shared memory */
+static int shmem_release_pages(char *rel_area)
+{
+ int ret = 0;
+
+ if (madvise(rel_area, nr_pages * page_size, MADV_REMOVE)) {
+ perror("madvise");
+ ret = 1;
+ }
+
+ return ret;
+}
+
+static void shmem_allocate_area(void **alloc_area)
+{
+ *alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
+ MAP_ANONYMOUS | MAP_SHARED, -1, 0);
+ if (*alloc_area == MAP_FAILED) {
+ fprintf(stderr, "shared memory mmap failed\n");
+ *alloc_area = NULL;
+ }
+}
+
+struct uffd_test_ops {
+ unsigned long expected_ioctls;
+ void (*allocate_area)(void **alloc_area);
+ int (*release_pages)(char *rel_area);
+ void (*alias_mapping)(__u64 *start, size_t len, unsigned long offset);
+};
+
+#define ANON_EXPECTED_IOCTLS ((1 << _UFFDIO_WAKE) | \
+ (1 << _UFFDIO_COPY) | \
+ (1 << _UFFDIO_ZEROPAGE))
+
+static struct uffd_test_ops anon_uffd_test_ops = {
+ .expected_ioctls = ANON_EXPECTED_IOCTLS,
+ .allocate_area = anon_allocate_area,
+ .release_pages = anon_release_pages,
+ .alias_mapping = noop_alias_mapping,
+};
+
+static struct uffd_test_ops shmem_uffd_test_ops = {
+ .expected_ioctls = ANON_EXPECTED_IOCTLS,
+ .allocate_area = shmem_allocate_area,
+ .release_pages = shmem_release_pages,
+ .alias_mapping = noop_alias_mapping,
+};
+
+static struct uffd_test_ops hugetlb_uffd_test_ops = {
+ .expected_ioctls = UFFD_API_RANGE_IOCTLS_BASIC,
+ .allocate_area = hugetlb_allocate_area,
+ .release_pages = hugetlb_release_pages,
+ .alias_mapping = hugetlb_alias_mapping,
+};
+
+static struct uffd_test_ops *uffd_test_ops;
+
+static int my_bcmp(char *str1, char *str2, size_t n)
+{
+ unsigned long i;
+ for (i = 0; i < n; i++)
+ if (str1[i] != str2[i])
+ return 1;
+ return 0;
+}
+
+static void *locking_thread(void *arg)
+{
+ unsigned long cpu = (unsigned long) arg;
+ struct random_data rand;
+ unsigned long page_nr = *(&(page_nr)); /* uninitialized warning */
+ int32_t rand_nr;
+ unsigned long long count;
+ char randstate[64];
+ unsigned int seed;
+ time_t start;
+
+ if (bounces & BOUNCE_RANDOM) {
+ seed = (unsigned int) time(NULL) - bounces;
+ if (!(bounces & BOUNCE_RACINGFAULTS))
+ seed += cpu;
+ bzero(&rand, sizeof(rand));
+ bzero(&randstate, sizeof(randstate));
+ if (initstate_r(seed, randstate, sizeof(randstate), &rand))
+ fprintf(stderr, "srandom_r error\n"), exit(1);
+ } else {
+ page_nr = -bounces;
+ if (!(bounces & BOUNCE_RACINGFAULTS))
+ page_nr += cpu * nr_pages_per_cpu;
+ }
+
+ while (!finished) {
+ if (bounces & BOUNCE_RANDOM) {
+ if (random_r(&rand, &rand_nr))
+ fprintf(stderr, "random_r 1 error\n"), exit(1);
+ page_nr = rand_nr;
+ if (sizeof(page_nr) > sizeof(rand_nr)) {
+ if (random_r(&rand, &rand_nr))
+ fprintf(stderr, "random_r 2 error\n"), exit(1);
+ page_nr |= (((unsigned long) rand_nr) << 16) <<
+ 16;
+ }
+ } else
+ page_nr += 1;
+ page_nr %= nr_pages;
+
+ start = time(NULL);
+ if (bounces & BOUNCE_VERIFY) {
+ count = *area_count(area_dst, page_nr);
+ if (!count)
+ fprintf(stderr,
+ "page_nr %lu wrong count %Lu %Lu\n",
+ page_nr, count,
+ count_verify[page_nr]), exit(1);
+
+
+ /*
+ * We can't use bcmp (or memcmp) because that
+ * returns 0 erroneously if the memory is
+ * changing under it (even if the end of the
+ * page is never changing and always
+ * different).
+ */
+#if 1
+ if (!my_bcmp(area_dst + page_nr * page_size, zeropage,
+ page_size))
+ fprintf(stderr,
+ "my_bcmp page_nr %lu wrong count %Lu %Lu\n",
+ page_nr, count,
+ count_verify[page_nr]), exit(1);
+#else
+ unsigned long loops;
+
+ loops = 0;
+ /* uncomment the below line to test with mutex */
+ /* pthread_mutex_lock(area_mutex(area_dst, page_nr)); */
+ while (!bcmp(area_dst + page_nr * page_size, zeropage,
+ page_size)) {
+ loops += 1;
+ if (loops > 10)
+ break;
+ }
+ /* uncomment below line to test with mutex */
+ /* pthread_mutex_unlock(area_mutex(area_dst, page_nr)); */
+ if (loops) {
+ fprintf(stderr,
+ "page_nr %lu all zero thread %lu %p %lu\n",
+ page_nr, cpu, area_dst + page_nr * page_size,
+ loops);
+ if (loops > 10)
+ exit(1);
+ }
+#endif
+ }
+
+ pthread_mutex_lock(area_mutex(area_dst, page_nr));
+ count = *area_count(area_dst, page_nr);
+ if (count != count_verify[page_nr]) {
+ fprintf(stderr,
+ "page_nr %lu memory corruption %Lu %Lu\n",
+ page_nr, count,
+ count_verify[page_nr]), exit(1);
+ }
+ count++;
+ *area_count(area_dst, page_nr) = count_verify[page_nr] = count;
+ pthread_mutex_unlock(area_mutex(area_dst, page_nr));
+
+ if (time(NULL) - start > 1)
+ fprintf(stderr,
+ "userfault too slow %ld "
+ "possible false positive with overcommit\n",
+ time(NULL) - start);
+ }
+
+ return NULL;
+}
+
+static void retry_copy_page(int ufd, struct uffdio_copy *uffdio_copy,
+ unsigned long offset)
+{
+ uffd_test_ops->alias_mapping(&uffdio_copy->dst,
+ uffdio_copy->len,
+ offset);
+ if (ioctl(ufd, UFFDIO_COPY, uffdio_copy)) {
+ /* real retval in ufdio_copy.copy */
+ if (uffdio_copy->copy != -EEXIST)
+ fprintf(stderr, "UFFDIO_COPY retry error %Ld\n",
+ uffdio_copy->copy), exit(1);
+ } else {
+ fprintf(stderr, "UFFDIO_COPY retry unexpected %Ld\n",
+ uffdio_copy->copy), exit(1);
+ }
+}
+
+static int __copy_page(int ufd, unsigned long offset, bool retry)
+{
+ struct uffdio_copy uffdio_copy;
+
+ if (offset >= nr_pages * page_size)
+ fprintf(stderr, "unexpected offset %lu\n",
+ offset), exit(1);
+ uffdio_copy.dst = (unsigned long) area_dst + offset;
+ uffdio_copy.src = (unsigned long) area_src + offset;
+ uffdio_copy.len = page_size;
+ uffdio_copy.mode = 0;
+ uffdio_copy.copy = 0;
+ if (ioctl(ufd, UFFDIO_COPY, &uffdio_copy)) {
+ /* real retval in ufdio_copy.copy */
+ if (uffdio_copy.copy != -EEXIST)
+ fprintf(stderr, "UFFDIO_COPY error %Ld\n",
+ uffdio_copy.copy), exit(1);
+ } else if (uffdio_copy.copy != page_size) {
+ fprintf(stderr, "UFFDIO_COPY unexpected copy %Ld\n",
+ uffdio_copy.copy), exit(1);
+ } else {
+ if (test_uffdio_copy_eexist && retry) {
+ test_uffdio_copy_eexist = false;
+ retry_copy_page(ufd, &uffdio_copy, offset);
+ }
+ return 1;
+ }
+ return 0;
+}
+
+static int copy_page_retry(int ufd, unsigned long offset)
+{
+ return __copy_page(ufd, offset, true);
+}
+
+static int copy_page(int ufd, unsigned long offset)
+{
+ return __copy_page(ufd, offset, false);
+}
+
+static void *uffd_poll_thread(void *arg)
+{
+ unsigned long cpu = (unsigned long) arg;
+ struct pollfd pollfd[2];
+ struct uffd_msg msg;
+ struct uffdio_register uffd_reg;
+ int ret;
+ unsigned long offset;
+ char tmp_chr;
+ unsigned long userfaults = 0;
+
+ pollfd[0].fd = uffd;
+ pollfd[0].events = POLLIN;
+ pollfd[1].fd = pipefd[cpu*2];
+ pollfd[1].events = POLLIN;
+
+ for (;;) {
+ ret = poll(pollfd, 2, -1);
+ if (!ret)
+ fprintf(stderr, "poll error %d\n", ret), exit(1);
+ if (ret < 0)
+ perror("poll"), exit(1);
+ if (pollfd[1].revents & POLLIN) {
+ if (read(pollfd[1].fd, &tmp_chr, 1) != 1)
+ fprintf(stderr, "read pipefd error\n"),
+ exit(1);
+ break;
+ }
+ if (!(pollfd[0].revents & POLLIN))
+ fprintf(stderr, "pollfd[0].revents %d\n",
+ pollfd[0].revents), exit(1);
+ ret = read(uffd, &msg, sizeof(msg));
+ if (ret < 0) {
+ if (errno == EAGAIN)
+ continue;
+ perror("nonblocking read error"), exit(1);
+ }
+ switch (msg.event) {
+ default:
+ fprintf(stderr, "unexpected msg event %u\n",
+ msg.event), exit(1);
+ break;
+ case UFFD_EVENT_PAGEFAULT:
+ 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))
+ userfaults++;
+ break;
+ case UFFD_EVENT_FORK:
+ close(uffd);
+ uffd = msg.arg.fork.ufd;
+ pollfd[0].fd = uffd;
+ break;
+ case UFFD_EVENT_REMOVE:
+ uffd_reg.range.start = msg.arg.remove.start;
+ uffd_reg.range.len = msg.arg.remove.end -
+ msg.arg.remove.start;
+ if (ioctl(uffd, UFFDIO_UNREGISTER, &uffd_reg.range))
+ fprintf(stderr, "remove failure\n"), exit(1);
+ break;
+ case UFFD_EVENT_REMAP:
+ area_dst = (char *)(unsigned long)msg.arg.remap.to;
+ break;
+ }
+ }
+ return (void *)userfaults;
+}
+
+pthread_mutex_t uffd_read_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static void *uffd_read_thread(void *arg)
+{
+ unsigned long *this_cpu_userfaults;
+ struct uffd_msg msg;
+ unsigned long offset;
+ int ret;
+
+ this_cpu_userfaults = (unsigned long *) arg;
+ *this_cpu_userfaults = 0;
+
+ pthread_mutex_unlock(&uffd_read_mutex);
+ /* from here cancellation is ok */
+
+ for (;;) {
+ ret = read(uffd, &msg, sizeof(msg));
+ if (ret != sizeof(msg)) {
+ if (ret < 0)
+ perror("blocking read error"), exit(1);
+ else
+ fprintf(stderr, "short read\n"), exit(1);
+ }
+ if (msg.event != UFFD_EVENT_PAGEFAULT)
+ fprintf(stderr, "unexpected msg event %u\n",
+ msg.event), exit(1);
+ if (bounces & BOUNCE_VERIFY &&
+ 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))
+ (*this_cpu_userfaults)++;
+ }
+ return (void *)NULL;
+}
+
+static void *background_thread(void *arg)
+{
+ unsigned long cpu = (unsigned long) arg;
+ unsigned long page_nr;
+
+ for (page_nr = cpu * nr_pages_per_cpu;
+ page_nr < (cpu+1) * nr_pages_per_cpu;
+ page_nr++)
+ copy_page_retry(uffd, page_nr * page_size);
+
+ return NULL;
+}
+
+static int stress(unsigned long *userfaults)
+{
+ unsigned long cpu;
+ pthread_t locking_threads[nr_cpus];
+ pthread_t uffd_threads[nr_cpus];
+ pthread_t background_threads[nr_cpus];
+ void **_userfaults = (void **) userfaults;
+
+ finished = 0;
+ for (cpu = 0; cpu < nr_cpus; cpu++) {
+ if (pthread_create(&locking_threads[cpu], &attr,
+ locking_thread, (void *)cpu))
+ return 1;
+ if (bounces & BOUNCE_POLL) {
+ if (pthread_create(&uffd_threads[cpu], &attr,
+ uffd_poll_thread, (void *)cpu))
+ return 1;
+ } else {
+ if (pthread_create(&uffd_threads[cpu], &attr,
+ uffd_read_thread,
+ &_userfaults[cpu]))
+ return 1;
+ pthread_mutex_lock(&uffd_read_mutex);
+ }
+ if (pthread_create(&background_threads[cpu], &attr,
+ background_thread, (void *)cpu))
+ return 1;
+ }
+ for (cpu = 0; cpu < nr_cpus; 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 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).
+ */
+ if (uffd_test_ops->release_pages(area_src))
+ return 1;
+
+ for (cpu = 0; cpu < nr_cpus; cpu++) {
+ char c;
+ if (bounces & BOUNCE_POLL) {
+ if (write(pipefd[cpu*2+1], &c, 1) != 1) {
+ fprintf(stderr, "pipefd write error\n");
+ return 1;
+ }
+ if (pthread_join(uffd_threads[cpu], &_userfaults[cpu]))
+ return 1;
+ } else {
+ if (pthread_cancel(uffd_threads[cpu]))
+ return 1;
+ if (pthread_join(uffd_threads[cpu], NULL))
+ return 1;
+ }
+ }
+
+ finished = 1;
+ for (cpu = 0; cpu < nr_cpus; cpu++)
+ if (pthread_join(locking_threads[cpu], NULL))
+ return 1;
+
+ return 0;
+}
+
+static int userfaultfd_open(int features)
+{
+ struct uffdio_api uffdio_api;
+
+ uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
+ if (uffd < 0) {
+ fprintf(stderr,
+ "userfaultfd syscall not available in this kernel\n");
+ return 1;
+ }
+ uffd_flags = fcntl(uffd, F_GETFD, NULL);
+
+ uffdio_api.api = UFFD_API;
+ uffdio_api.features = features;
+ if (ioctl(uffd, UFFDIO_API, &uffdio_api)) {
+ fprintf(stderr, "UFFDIO_API\n");
+ return 1;
+ }
+ if (uffdio_api.api != UFFD_API) {
+ fprintf(stderr, "UFFDIO_API error %Lu\n", uffdio_api.api);
+ return 1;
+ }
+
+ return 0;
+}
+
+sigjmp_buf jbuf, *sigbuf;
+
+static void sighndl(int sig, siginfo_t *siginfo, void *ptr)
+{
+ if (sig == SIGBUS) {
+ if (sigbuf)
+ siglongjmp(*sigbuf, 1);
+ abort();
+ }
+}
+
+/*
+ * For non-cooperative userfaultfd test we fork() a process that will
+ * generate pagefaults, will mremap the area monitored by the
+ * userfaultfd and at last this process will release the monitored
+ * area.
+ * For the anonymous and shared memory the area is divided into two
+ * parts, the first part is accessed before mremap, and the second
+ * part is accessed after mremap. Since hugetlbfs does not support
+ * mremap, the entire monitored area is accessed in a single pass for
+ * HUGETLB_TEST.
+ * The release of the pages currently generates event for shmem and
+ * anonymous memory (UFFD_EVENT_REMOVE), hence it is not checked
+ * for hugetlb.
+ * For signal test(UFFD_FEATURE_SIGBUS), signal_test = 1, we register
+ * monitored area, generate pagefaults and test that signal is delivered.
+ * Use UFFDIO_COPY to allocate missing page and retry. For signal_test = 2
+ * test robustness use case - we release monitored area, fork a process
+ * that will generate pagefaults and verify signal is generated.
+ * This also tests UFFD_FEATURE_EVENT_FORK event along with the signal
+ * feature. Using monitor thread, verify no userfault events are generated.
+ */
+static int faulting_process(int signal_test)
+{
+ unsigned long nr;
+ unsigned long long count;
+ unsigned long split_nr_pages;
+ unsigned long lastnr;
+ struct sigaction act;
+ unsigned long signalled = 0;
+
+ if (test_type != TEST_HUGETLB)
+ split_nr_pages = (nr_pages + 1) / 2;
+ else
+ split_nr_pages = nr_pages;
+
+ if (signal_test) {
+ sigbuf = &jbuf;
+ memset(&act, 0, sizeof(act));
+ act.sa_sigaction = sighndl;
+ act.sa_flags = SA_SIGINFO;
+ if (sigaction(SIGBUS, &act, 0)) {
+ perror("sigaction");
+ return 1;
+ }
+ lastnr = (unsigned long)-1;
+ }
+
+ for (nr = 0; nr < split_nr_pages; nr++) {
+ if (signal_test) {
+ if (sigsetjmp(*sigbuf, 1) != 0) {
+ if (nr == lastnr) {
+ fprintf(stderr, "Signal repeated\n");
+ return 1;
+ }
+
+ lastnr = nr;
+ if (signal_test == 1) {
+ if (copy_page(uffd, nr * page_size))
+ signalled++;
+ } else {
+ signalled++;
+ continue;
+ }
+ }
+ }
+
+ count = *area_count(area_dst, nr);
+ if (count != count_verify[nr]) {
+ fprintf(stderr,
+ "nr %lu memory corruption %Lu %Lu\n",
+ nr, count,
+ count_verify[nr]), exit(1);
+ }
+ }
+
+ if (signal_test)
+ return signalled != split_nr_pages;
+
+ if (test_type == TEST_HUGETLB)
+ return 0;
+
+ area_dst = mremap(area_dst, nr_pages * page_size, nr_pages * page_size,
+ MREMAP_MAYMOVE | MREMAP_FIXED, area_src);
+ if (area_dst == MAP_FAILED)
+ perror("mremap"), exit(1);
+
+ for (; nr < nr_pages; nr++) {
+ count = *area_count(area_dst, nr);
+ if (count != count_verify[nr]) {
+ fprintf(stderr,
+ "nr %lu memory corruption %Lu %Lu\n",
+ nr, count,
+ count_verify[nr]), exit(1);
+ }
+ }
+
+ if (uffd_test_ops->release_pages(area_dst))
+ return 1;
+
+ for (nr = 0; nr < nr_pages; nr++) {
+ if (my_bcmp(area_dst + nr * page_size, zeropage, page_size))
+ fprintf(stderr, "nr %lu is not zero\n", nr), exit(1);
+ }
+
+ return 0;
+}
+
+static void retry_uffdio_zeropage(int ufd,
+ struct uffdio_zeropage *uffdio_zeropage,
+ unsigned long offset)
+{
+ uffd_test_ops->alias_mapping(&uffdio_zeropage->range.start,
+ uffdio_zeropage->range.len,
+ offset);
+ if (ioctl(ufd, UFFDIO_ZEROPAGE, uffdio_zeropage)) {
+ if (uffdio_zeropage->zeropage != -EEXIST)
+ fprintf(stderr, "UFFDIO_ZEROPAGE retry error %Ld\n",
+ uffdio_zeropage->zeropage), exit(1);
+ } else {
+ fprintf(stderr, "UFFDIO_ZEROPAGE retry unexpected %Ld\n",
+ uffdio_zeropage->zeropage), exit(1);
+ }
+}
+
+static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
+{
+ struct uffdio_zeropage uffdio_zeropage;
+ int ret;
+ unsigned long has_zeropage;
+
+ has_zeropage = uffd_test_ops->expected_ioctls & (1 << _UFFDIO_ZEROPAGE);
+
+ if (offset >= nr_pages * page_size)
+ fprintf(stderr, "unexpected offset %lu\n",
+ offset), exit(1);
+ uffdio_zeropage.range.start = (unsigned long) area_dst + offset;
+ uffdio_zeropage.range.len = page_size;
+ uffdio_zeropage.mode = 0;
+ ret = ioctl(ufd, UFFDIO_ZEROPAGE, &uffdio_zeropage);
+ if (ret) {
+ /* real retval in ufdio_zeropage.zeropage */
+ if (has_zeropage) {
+ if (uffdio_zeropage.zeropage == -EEXIST)
+ fprintf(stderr, "UFFDIO_ZEROPAGE -EEXIST\n"),
+ exit(1);
+ else
+ fprintf(stderr, "UFFDIO_ZEROPAGE error %Ld\n",
+ uffdio_zeropage.zeropage), exit(1);
+ } else {
+ if (uffdio_zeropage.zeropage != -EINVAL)
+ fprintf(stderr,
+ "UFFDIO_ZEROPAGE not -EINVAL %Ld\n",
+ uffdio_zeropage.zeropage), exit(1);
+ }
+ } else if (has_zeropage) {
+ if (uffdio_zeropage.zeropage != page_size) {
+ fprintf(stderr, "UFFDIO_ZEROPAGE unexpected %Ld\n",
+ uffdio_zeropage.zeropage), exit(1);
+ } else {
+ if (test_uffdio_zeropage_eexist && retry) {
+ test_uffdio_zeropage_eexist = false;
+ retry_uffdio_zeropage(ufd, &uffdio_zeropage,
+ offset);
+ }
+ return 1;
+ }
+ } else {
+ fprintf(stderr,
+ "UFFDIO_ZEROPAGE succeeded %Ld\n",
+ uffdio_zeropage.zeropage), exit(1);
+ }
+
+ return 0;
+}
+
+static int uffdio_zeropage(int ufd, unsigned long offset)
+{
+ return __uffdio_zeropage(ufd, offset, false);
+}
+
+/* exercise UFFDIO_ZEROPAGE */
+static int userfaultfd_zeropage_test(void)
+{
+ struct uffdio_register uffdio_register;
+ unsigned long expected_ioctls;
+
+ printf("testing UFFDIO_ZEROPAGE: ");
+ fflush(stdout);
+
+ if (uffd_test_ops->release_pages(area_dst))
+ return 1;
+
+ if (userfaultfd_open(0) < 0)
+ return 1;
+ uffdio_register.range.start = (unsigned long) area_dst;
+ uffdio_register.range.len = nr_pages * page_size;
+ uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
+ if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
+ fprintf(stderr, "register failure\n"), exit(1);
+
+ expected_ioctls = uffd_test_ops->expected_ioctls;
+ if ((uffdio_register.ioctls & expected_ioctls) !=
+ expected_ioctls)
+ fprintf(stderr,
+ "unexpected missing ioctl for anon memory\n"),
+ exit(1);
+
+ if (uffdio_zeropage(uffd, 0)) {
+ if (my_bcmp(area_dst, zeropage, page_size))
+ fprintf(stderr, "zeropage is not zero\n"), exit(1);
+ }
+
+ close(uffd);
+ printf("done.\n");
+ return 0;
+}
+
+static int userfaultfd_events_test(void)
+{
+ struct uffdio_register uffdio_register;
+ unsigned long expected_ioctls;
+ unsigned long userfaults;
+ pthread_t uffd_mon;
+ int err, features;
+ pid_t pid;
+ char c;
+
+ printf("testing events (fork, remap, remove): ");
+ fflush(stdout);
+
+ if (uffd_test_ops->release_pages(area_dst))
+ return 1;
+
+ features = UFFD_FEATURE_EVENT_FORK | UFFD_FEATURE_EVENT_REMAP |
+ UFFD_FEATURE_EVENT_REMOVE;
+ if (userfaultfd_open(features) < 0)
+ return 1;
+ fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
+
+ uffdio_register.range.start = (unsigned long) area_dst;
+ uffdio_register.range.len = nr_pages * page_size;
+ uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
+ if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
+ fprintf(stderr, "register failure\n"), exit(1);
+
+ expected_ioctls = uffd_test_ops->expected_ioctls;
+ if ((uffdio_register.ioctls & expected_ioctls) !=
+ expected_ioctls)
+ fprintf(stderr,
+ "unexpected missing ioctl for anon memory\n"),
+ exit(1);
+
+ if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, NULL))
+ perror("uffd_poll_thread create"), exit(1);
+
+ pid = fork();
+ if (pid < 0)
+ perror("fork"), exit(1);
+
+ if (!pid)
+ return faulting_process(0);
+
+ waitpid(pid, &err, 0);
+ if (err)
+ fprintf(stderr, "faulting process failed\n"), exit(1);
+
+ if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
+ perror("pipe write"), exit(1);
+ if (pthread_join(uffd_mon, (void **)&userfaults))
+ return 1;
+
+ close(uffd);
+ printf("userfaults: %ld\n", userfaults);
+
+ return userfaults != nr_pages;
+}
+
+static int userfaultfd_sig_test(void)
+{
+ struct uffdio_register uffdio_register;
+ unsigned long expected_ioctls;
+ unsigned long userfaults;
+ pthread_t uffd_mon;
+ int err, features;
+ pid_t pid;
+ char c;
+
+ printf("testing signal delivery: ");
+ fflush(stdout);
+
+ if (uffd_test_ops->release_pages(area_dst))
+ return 1;
+
+ features = UFFD_FEATURE_EVENT_FORK|UFFD_FEATURE_SIGBUS;
+ if (userfaultfd_open(features) < 0)
+ return 1;
+ fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
+
+ uffdio_register.range.start = (unsigned long) area_dst;
+ uffdio_register.range.len = nr_pages * page_size;
+ uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
+ if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
+ fprintf(stderr, "register failure\n"), exit(1);
+
+ expected_ioctls = uffd_test_ops->expected_ioctls;
+ if ((uffdio_register.ioctls & expected_ioctls) !=
+ expected_ioctls)
+ fprintf(stderr,
+ "unexpected missing ioctl for anon memory\n"),
+ exit(1);
+
+ if (faulting_process(1))
+ fprintf(stderr, "faulting process failed\n"), exit(1);
+
+ if (uffd_test_ops->release_pages(area_dst))
+ return 1;
+
+ if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, NULL))
+ perror("uffd_poll_thread create"), exit(1);
+
+ pid = fork();
+ if (pid < 0)
+ perror("fork"), exit(1);
+
+ if (!pid)
+ exit(faulting_process(2));
+
+ waitpid(pid, &err, 0);
+ if (err)
+ fprintf(stderr, "faulting process failed\n"), exit(1);
+
+ if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
+ perror("pipe write"), exit(1);
+ if (pthread_join(uffd_mon, (void **)&userfaults))
+ return 1;
+
+ printf("done.\n");
+ if (userfaults)
+ fprintf(stderr, "Signal test failed, userfaults: %ld\n",
+ userfaults);
+ close(uffd);
+ return userfaults != 0;
+}
+static int userfaultfd_stress(void)
+{
+ void *area;
+ char *tmp_area;
+ unsigned long nr;
+ struct uffdio_register uffdio_register;
+ unsigned long cpu;
+ int err;
+ unsigned long userfaults[nr_cpus];
+
+ uffd_test_ops->allocate_area((void **)&area_src);
+ if (!area_src)
+ return 1;
+ uffd_test_ops->allocate_area((void **)&area_dst);
+ if (!area_dst)
+ return 1;
+
+ if (userfaultfd_open(0) < 0)
+ return 1;
+
+ count_verify = malloc(nr_pages * sizeof(unsigned long long));
+ if (!count_verify) {
+ perror("count_verify");
+ return 1;
+ }
+
+ for (nr = 0; nr < nr_pages; nr++) {
+ *area_mutex(area_src, nr) = (pthread_mutex_t)
+ PTHREAD_MUTEX_INITIALIZER;
+ count_verify[nr] = *area_count(area_src, nr) = 1;
+ /*
+ * In the transition between 255 to 256, powerpc will
+ * read out of order in my_bcmp and see both bytes as
+ * zero, so leave a placeholder below always non-zero
+ * after the count, to avoid my_bcmp to trigger false
+ * positives.
+ */
+ *(area_count(area_src, nr) + 1) = 1;
+ }
+
+ pipefd = malloc(sizeof(int) * nr_cpus * 2);
+ if (!pipefd) {
+ perror("pipefd");
+ return 1;
+ }
+ for (cpu = 0; cpu < nr_cpus; cpu++) {
+ if (pipe2(&pipefd[cpu*2], O_CLOEXEC | O_NONBLOCK)) {
+ perror("pipe");
+ return 1;
+ }
+ }
+
+ if (posix_memalign(&area, page_size, page_size)) {
+ fprintf(stderr, "out of memory\n");
+ return 1;
+ }
+ zeropage = area;
+ bzero(zeropage, page_size);
+
+ pthread_mutex_lock(&uffd_read_mutex);
+
+ pthread_attr_init(&attr);
+ pthread_attr_setstacksize(&attr, 16*1024*1024);
+
+ err = 0;
+ while (bounces--) {
+ unsigned long expected_ioctls;
+
+ 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");
+ printf(", ");
+ fflush(stdout);
+
+ if (bounces & BOUNCE_POLL)
+ fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
+ else
+ fcntl(uffd, F_SETFL, uffd_flags & ~O_NONBLOCK);
+
+ /* register */
+ uffdio_register.range.start = (unsigned long) area_dst;
+ uffdio_register.range.len = nr_pages * page_size;
+ uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
+ if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register)) {
+ fprintf(stderr, "register failure\n");
+ return 1;
+ }
+ expected_ioctls = uffd_test_ops->expected_ioctls;
+ if ((uffdio_register.ioctls & expected_ioctls) !=
+ expected_ioctls) {
+ fprintf(stderr,
+ "unexpected missing ioctl for anon memory\n");
+ return 1;
+ }
+
+ if (area_dst_alias) {
+ uffdio_register.range.start = (unsigned long)
+ area_dst_alias;
+ if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register)) {
+ fprintf(stderr, "register failure alias\n");
+ return 1;
+ }
+ }
+
+ /*
+ * 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.
+ */
+ if (uffd_test_ops->release_pages(area_dst))
+ return 1;
+
+ /* bounce pass */
+ if (stress(userfaults))
+ return 1;
+
+ /* unregister */
+ if (ioctl(uffd, UFFDIO_UNREGISTER, &uffdio_register.range)) {
+ fprintf(stderr, "unregister failure\n");
+ return 1;
+ }
+ if (area_dst_alias) {
+ uffdio_register.range.start = (unsigned long) area_dst;
+ if (ioctl(uffd, UFFDIO_UNREGISTER,
+ &uffdio_register.range)) {
+ fprintf(stderr, "unregister failure alias\n");
+ return 1;
+ }
+ }
+
+ /* verification */
+ if (bounces & BOUNCE_VERIFY) {
+ for (nr = 0; nr < nr_pages; nr++) {
+ if (*area_count(area_dst, nr) != count_verify[nr]) {
+ fprintf(stderr,
+ "error area_count %Lu %Lu %lu\n",
+ *area_count(area_src, nr),
+ count_verify[nr],
+ nr);
+ err = 1;
+ bounces = 0;
+ }
+ }
+ }
+
+ /* prepare next bounce */
+ tmp_area = area_src;
+ area_src = area_dst;
+ area_dst = tmp_area;
+
+ tmp_area = area_src_alias;
+ area_src_alias = area_dst_alias;
+ area_dst_alias = tmp_area;
+
+ printf("userfaults:");
+ for (cpu = 0; cpu < nr_cpus; cpu++)
+ printf(" %lu", userfaults[cpu]);
+ printf("\n");
+ }
+
+ if (err)
+ return err;
+
+ close(uffd);
+ return userfaultfd_zeropage_test() || userfaultfd_sig_test()
+ || userfaultfd_events_test();
+}
+
+/*
+ * Copied from mlock2-tests.c
+ */
+unsigned long default_huge_page_size(void)
+{
+ unsigned long hps = 0;
+ char *line = NULL;
+ size_t linelen = 0;
+ FILE *f = fopen("/proc/meminfo", "r");
+
+ if (!f)
+ return 0;
+ while (getline(&line, &linelen, f) > 0) {
+ if (sscanf(line, "Hugepagesize: %lu kB", &hps) == 1) {
+ hps <<= 10;
+ break;
+ }
+ }
+
+ free(line);
+ fclose(f);
+ return hps;
+}
+
+static void set_test_type(const char *type)
+{
+ if (!strcmp(type, "anon")) {
+ test_type = TEST_ANON;
+ uffd_test_ops = &anon_uffd_test_ops;
+ } else if (!strcmp(type, "hugetlb")) {
+ test_type = TEST_HUGETLB;
+ uffd_test_ops = &hugetlb_uffd_test_ops;
+ } else if (!strcmp(type, "hugetlb_shared")) {
+ map_shared = true;
+ test_type = TEST_HUGETLB;
+ uffd_test_ops = &hugetlb_uffd_test_ops;
+ } else if (!strcmp(type, "shmem")) {
+ map_shared = true;
+ test_type = TEST_SHMEM;
+ uffd_test_ops = &shmem_uffd_test_ops;
+ } else {
+ fprintf(stderr, "Unknown test type: %s\n", type), exit(1);
+ }
+
+ if (test_type == TEST_HUGETLB)
+ page_size = default_huge_page_size();
+ else
+ page_size = sysconf(_SC_PAGE_SIZE);
+
+ if (!page_size)
+ fprintf(stderr, "Unable to determine page size\n"),
+ exit(2);
+ if ((unsigned long) area_count(NULL, 0) + sizeof(unsigned long long) * 2
+ > page_size)
+ fprintf(stderr, "Impossible to run this test\n"), exit(2);
+}
+
+static void sigalrm(int sig)
+{
+ if (sig != SIGALRM)
+ abort();
+ test_uffdio_copy_eexist = true;
+ test_uffdio_zeropage_eexist = true;
+ alarm(ALARM_INTERVAL_SECS);
+}
+
+int main(int argc, char **argv)
+{
+ if (argc < 4)
+ fprintf(stderr, "Usage: <test type> <MiB> <bounces> [hugetlbfs_file]\n"),
+ exit(1);
+
+ if (signal(SIGALRM, sigalrm) == SIG_ERR)
+ fprintf(stderr, "failed to arm SIGALRM"), exit(1);
+ alarm(ALARM_INTERVAL_SECS);
+
+ set_test_type(argv[1]);
+
+ nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
+ nr_pages_per_cpu = atol(argv[2]) * 1024*1024 / page_size /
+ nr_cpus;
+ if (!nr_pages_per_cpu) {
+ fprintf(stderr, "invalid MiB\n");
+ fprintf(stderr, "Usage: <MiB> <bounces>\n"), exit(1);
+ }
+
+ bounces = atoi(argv[3]);
+ if (bounces <= 0) {
+ fprintf(stderr, "invalid bounces\n");
+ fprintf(stderr, "Usage: <MiB> <bounces>\n"), exit(1);
+ }
+ nr_pages = nr_pages_per_cpu * nr_cpus;
+
+ if (test_type == TEST_HUGETLB) {
+ if (argc < 5)
+ fprintf(stderr, "Usage: hugetlb <MiB> <bounces> <hugetlbfs_file>\n"),
+ exit(1);
+ huge_fd = open(argv[4], O_CREAT | O_RDWR, 0755);
+ if (huge_fd < 0) {
+ fprintf(stderr, "Open of %s failed", argv[3]);
+ perror("open");
+ exit(1);
+ }
+ if (ftruncate(huge_fd, 0)) {
+ fprintf(stderr, "ftruncate %s to size 0 failed", argv[3]);
+ perror("ftruncate");
+ exit(1);
+ }
+ }
+ printf("nr_pages: %lu, nr_pages_per_cpu: %lu\n",
+ nr_pages, nr_pages_per_cpu);
+ return userfaultfd_stress();
+}
+
+#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 */