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linux/tools/testing/selftests/vm/userfaultfd.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).
*/
#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 <assert.h>
#include <inttypes.h>
#include <stdint.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;
/* Whether to test uffd write-protection */
static bool test_uffdio_wp = false;
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;
/* Userfaultfd test statistics */
struct uffd_stats {
int cpu;
unsigned long missing_faults;
unsigned long wp_faults;
};
/* 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)))
const char *examples =
"# Run anonymous memory test on 100MiB region with 99999 bounces:\n"
"./userfaultfd anon 100 99999\n\n"
"# Run share memory test on 1GiB region with 99 bounces:\n"
"./userfaultfd shmem 1000 99\n\n"
"# Run hugetlb memory test on 256MiB region with 50 bounces (using /dev/hugepages/hugefile):\n"
"./userfaultfd hugetlb 256 50 /dev/hugepages/hugefile\n\n"
"# Run the same hugetlb test but using shmem:\n"
"./userfaultfd hugetlb_shared 256 50 /dev/hugepages/hugefile\n\n"
"# 10MiB-~6GiB 999 bounces anonymous test, "
"continue forever unless an error triggers\n"
"while ./userfaultfd anon $[RANDOM % 6000 + 10] 999; do true; done\n\n";
static void usage(void)
{
fprintf(stderr, "\nUsage: ./userfaultfd <test type> <MiB> <bounces> "
"[hugetlbfs_file]\n\n");
fprintf(stderr, "Supported <test type>: anon, hugetlb, "
"hugetlb_shared, shmem\n\n");
fprintf(stderr, "Examples:\n\n");
fprintf(stderr, "%s", examples);
exit(1);
}
#define uffd_error(code, fmt, ...) \
do { \
fprintf(stderr, fmt, ##__VA_ARGS__); \
fprintf(stderr, ": %" PRId64 "\n", (int64_t)(code)); \
exit(1); \
} while (0)
static void uffd_stats_reset(struct uffd_stats *uffd_stats,
unsigned long n_cpus)
{
int i;
for (i = 0; i < n_cpus; i++) {
uffd_stats[i].cpu = i;
uffd_stats[i].missing_faults = 0;
uffd_stats[i].wp_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;
for (i = 0; i < n_cpus; i++) {
miss_total += stats[i].missing_faults;
wp_total += stats[i].wp_faults;
}
printf("userfaults: %llu missing (", miss_total);
for (i = 0; i < n_cpus; i++)
printf("%lu+", stats[i].missing_faults);
printf("\b), %llu wp (", wp_total);
for (i = 0; i < n_cpus; i++)
printf("%lu+", stats[i].wp_faults);
printf("\b)\n");
}
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) {
perror("mmap of hugetlbfs file failed");
goto fail;
}
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) {
perror("mmap of hugetlb file alias failed");
goto fail_munmap;
}
}
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;
return;
fail_munmap:
if (munmap(*alloc_area, nr_pages * page_size) < 0) {
perror("hugetlb munmap");
exit(1);
}
fail:
*alloc_area = NULL;
}
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 SHMEM_EXPECTED_IOCTLS ((1 << _UFFDIO_WAKE) | \
(1 << _UFFDIO_COPY) | \
(1 << _UFFDIO_ZEROPAGE))
#define ANON_EXPECTED_IOCTLS ((1 << _UFFDIO_WAKE) | \
(1 << _UFFDIO_COPY) | \
(1 << _UFFDIO_ZEROPAGE) | \
(1 << _UFFDIO_WRITEPROTECT))
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 = SHMEM_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 wp_range(int ufd, __u64 start, __u64 len, bool wp)
{
struct uffdio_writeprotect prms;
/* Write protection page faults */
prms.range.start = start;
prms.range.len = len;
/* Undo write-protect, do wakeup after that */
prms.mode = wp ? UFFDIO_WRITEPROTECT_MODE_WP : 0;
if (ioctl(ufd, UFFDIO_WRITEPROTECT, &prms)) {
fprintf(stderr, "clear WP failed for address 0x%" PRIx64 "\n",
(uint64_t)start);
exit(1);
}
}
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) {
uffd_error(uffdio_copy->copy,
"UFFDIO_COPY retry error");
}
} else
uffd_error(uffdio_copy->copy, "UFFDIO_COPY retry unexpected");
}
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;
if (test_uffdio_wp)
uffdio_copy.mode = UFFDIO_COPY_MODE_WP;
else
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)
uffd_error(uffdio_copy.copy, "UFFDIO_COPY error");
} else if (uffdio_copy.copy != page_size) {
uffd_error(uffdio_copy.copy, "UFFDIO_COPY unexpected copy");
} 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 int uffd_read_msg(int ufd, struct uffd_msg *msg)
{
int ret = read(uffd, msg, sizeof(*msg));
if (ret != sizeof(*msg)) {
if (ret < 0) {
if (errno == EAGAIN)
return 1;
perror("blocking read error");
} else {
fprintf(stderr, "short read\n");
}
exit(1);
}
return 0;
}
static void uffd_handle_page_fault(struct uffd_msg *msg,
struct uffd_stats *stats)
{
unsigned long offset;
if (msg->event != UFFD_EVENT_PAGEFAULT) {
fprintf(stderr, "unexpected msg event %u\n", msg->event);
exit(1);
}
if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WP) {
wp_range(uffd, msg->arg.pagefault.address, page_size, false);
stats->wp_faults++;
} else {
/* Missing page faults */
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))
stats->missing_faults++;
}
}
static void *uffd_poll_thread(void *arg)
{
struct uffd_stats *stats = (struct uffd_stats *)arg;
unsigned long cpu = stats->cpu;
struct pollfd pollfd[2];
struct uffd_msg msg;
struct uffdio_register uffd_reg;
int ret;
char tmp_chr;
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);
}
if (uffd_read_msg(uffd, &msg))
continue;
switch (msg.event) {
default:
fprintf(stderr, "unexpected msg event %u\n",
msg.event); exit(1);
break;
case UFFD_EVENT_PAGEFAULT:
uffd_handle_page_fault(&msg, stats);
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 NULL;
}
pthread_mutex_t uffd_read_mutex = PTHREAD_MUTEX_INITIALIZER;
static void *uffd_read_thread(void *arg)
{
struct uffd_stats *stats = (struct uffd_stats *)arg;
struct uffd_msg msg;
pthread_mutex_unlock(&uffd_read_mutex);
/* from here cancellation is ok */
for (;;) {
if (uffd_read_msg(uffd, &msg))
continue;
uffd_handle_page_fault(&msg, stats);
}
return NULL;
}
static void *background_thread(void *arg)
{
unsigned long cpu = (unsigned long) arg;
unsigned long page_nr, start_nr, mid_nr, end_nr;
start_nr = cpu * nr_pages_per_cpu;
end_nr = (cpu+1) * 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(uffd, page_nr * 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 (test_uffdio_wp)
wp_range(uffd, (unsigned long)area_dst + start_nr * page_size,
nr_pages_per_cpu * 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(uffd, page_nr * page_size);
return NULL;
}
static int stress(struct uffd_stats *uffd_stats)
{
unsigned long cpu;
pthread_t locking_threads[nr_cpus];
pthread_t uffd_threads[nr_cpus];
pthread_t background_threads[nr_cpus];
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 *)&uffd_stats[cpu]))
return 1;
} else {
if (pthread_create(&uffd_threads[cpu], &attr,
uffd_read_thread,
(void *)&uffd_stats[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;
finished = 1;
for (cpu = 0; cpu < nr_cpus; cpu++)
if (pthread_join(locking_threads[cpu], NULL))
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],
(void *)&uffd_stats[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_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 failed.\nPlease make sure to "
"run with either root or ptrace capability.\n");
return 1;
}
if (uffdio_api.api != UFFD_API) {
fprintf(stderr, "UFFDIO_API error: %" PRIu64 "\n",
(uint64_t)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++) {
int steps = 1;
unsigned long offset = nr * page_size;
if (signal_test) {
if (sigsetjmp(*sigbuf, 1) != 0) {
if (steps == 1 && nr == lastnr) {
fprintf(stderr, "Signal repeated\n");
return 1;
}
lastnr = nr;
if (signal_test == 1) {
if (steps == 1) {
/* This is a MISSING request */
steps++;
if (copy_page(uffd, offset))
signalled++;
} else {
/* This is a WP request */
assert(steps == 2);
wp_range(uffd,
(__u64)area_dst +
offset,
page_size, false);
}
} 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]);
}
/*
* Trigger write protection if there is by writing
* the same value back.
*/
*area_count(area_dst, nr) = count;
}
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);
}
/*
* Trigger write protection if there is by writing
* the same value back.
*/
*area_count(area_dst, nr) = count;
}
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) {
uffd_error(uffdio_zeropage->zeropage,
"UFFDIO_ZEROPAGE retry error");
}
} else {
uffd_error(uffdio_zeropage->zeropage,
"UFFDIO_ZEROPAGE retry unexpected");
}
}
static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
{
struct uffdio_zeropage uffdio_zeropage;
int ret;
unsigned long has_zeropage;
__s64 res;
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);
res = uffdio_zeropage.zeropage;
if (ret) {
/* real retval in ufdio_zeropage.zeropage */
if (has_zeropage) {
uffd_error(res, "UFFDIO_ZEROPAGE %s",
res == -EEXIST ? "-EEXIST" : "error");
} else if (res != -EINVAL)
uffd_error(res, "UFFDIO_ZEROPAGE not -EINVAL");
} else if (has_zeropage) {
if (res != page_size) {
uffd_error(res, "UFFDIO_ZEROPAGE unexpected");
} else {
if (test_uffdio_zeropage_eexist && retry) {
test_uffdio_zeropage_eexist = false;
retry_uffdio_zeropage(ufd, &uffdio_zeropage,
offset);
}
return 1;
}
} else
uffd_error(res, "UFFDIO_ZEROPAGE succeeded");
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))
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 (test_uffdio_wp)
uffdio_register.mode |= UFFDIO_REGISTER_MODE_WP;
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;
pthread_t uffd_mon;
int err, features;
pid_t pid;
char c;
struct uffd_stats stats = { 0 };
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))
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 (test_uffdio_wp)
uffdio_register.mode |= UFFDIO_REGISTER_MODE_WP;
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, &stats)) {
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, NULL))
return 1;
close(uffd);
uffd_stats_report(&stats, 1);
return stats.missing_faults != 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;
struct uffd_stats stats = { 0 };
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))
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 (test_uffdio_wp)
uffdio_register.mode |= UFFDIO_REGISTER_MODE_WP;
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, &stats)) {
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;
struct uffd_stats uffd_stats[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))
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");
else
printf(" read");
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 (test_uffdio_wp)
uffdio_register.mode |= UFFDIO_REGISTER_MODE_WP;
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;
uffd_stats_reset(uffd_stats, nr_cpus);
/* bounce pass */
if (stress(uffd_stats))
return 1;
/* Clear all the write protections if there is any */
if (test_uffdio_wp)
wp_range(uffd, (unsigned long)area_dst,
nr_pages * page_size, false);
/* 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;
uffd_stats_report(uffd_stats, nr_cpus);
}
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;
/* Only enable write-protect test for anonymous test */
test_uffdio_wp = true;
} 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)
usage();
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");
usage();
}
bounces = atoi(argv[3]);
if (bounces <= 0) {
fprintf(stderr, "invalid bounces\n");
usage();
}
nr_pages = nr_pages_per_cpu * nr_cpus;
if (test_type == TEST_HUGETLB) {
if (argc < 5)
usage();
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 */
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