diff options
Diffstat (limited to 'tools/testing/selftests/vm/userfaultfd.c')
| -rw-r--r-- | tools/testing/selftests/vm/userfaultfd.c | 636 |
1 files changed, 636 insertions, 0 deletions
diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c new file mode 100644 index 000000000000..0c0b83953352 --- /dev/null +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -0,0 +1,636 @@ +/* + * 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 <pthread.h> +#include "../../../../include/uapi/linux/userfaultfd.h" + +#ifdef __x86_64__ +#define __NR_userfaultfd 323 +#elif defined(__i386__) +#define __NR_userfaultfd 359 +#elif defined(__powewrpc__) +#define __NR_userfaultfd 364 +#else +#error "missing __NR_userfaultfd definition" +#endif + +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; + +static unsigned long long *count_verify; +static int uffd, finished, *pipefd; +static char *area_src, *area_dst; +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 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) << 32; + } + } 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 int copy_page(unsigned long offset) +{ + 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(uffd, 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 + return 1; + return 0; +} + +static void *uffd_poll_thread(void *arg) +{ + unsigned long cpu = (unsigned long) arg; + struct pollfd pollfd[2]; + struct uffd_msg msg; + 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); + } + 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_WRITE) + fprintf(stderr, "unexpected write fault\n"), exit(1); + offset = (char *)msg.arg.pagefault.address - area_dst; + offset &= ~(page_size-1); + if (copy_page(offset)) + userfaults++; + } + 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 *)msg.arg.pagefault.address - area_dst; + offset &= ~(page_size-1); + if (copy_page(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(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 (madvise(area_src, nr_pages * page_size, MADV_DONTNEED)) { + perror("madvise"); + 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_stress(void) +{ + void *area; + char *tmp_area; + unsigned long nr; + struct uffdio_register uffdio_register; + struct uffdio_api uffdio_api; + unsigned long cpu; + int uffd_flags; + unsigned long userfaults[nr_cpus]; + + if (posix_memalign(&area, page_size, nr_pages * page_size)) { + fprintf(stderr, "out of memory\n"); + return 1; + } + area_src = area; + if (posix_memalign(&area, page_size, nr_pages * page_size)) { + fprintf(stderr, "out of memory\n"); + return 1; + } + area_dst = area; + + 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 = 0; + 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; + } + + 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; + } + + 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); + + 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 = (1 << _UFFDIO_WAKE) | + (1 << _UFFDIO_COPY) | + (1 << _UFFDIO_ZEROPAGE); + if ((uffdio_register.ioctls & expected_ioctls) != + expected_ioctls) { + fprintf(stderr, + "unexpected missing ioctl for anon memory\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 (madvise(area_dst, nr_pages * page_size, MADV_DONTNEED)) { + perror("madvise 2"); + return 1; + } + + /* bounce pass */ + if (stress(userfaults)) + return 1; + + /* unregister */ + if (ioctl(uffd, UFFDIO_UNREGISTER, &uffdio_register.range)) { + fprintf(stderr, "register failure\n"); + return 1; + } + + /* verification */ + if (bounces & BOUNCE_VERIFY) { + for (nr = 0; nr < nr_pages; nr++) { + if (my_bcmp(area_dst, + area_dst + nr * page_size, + sizeof(pthread_mutex_t))) { + fprintf(stderr, + "error mutex 2 %lu\n", + nr); + bounces = 0; + } + 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); + bounces = 0; + } + } + } + + /* prepare next bounce */ + tmp_area = area_src; + area_src = area_dst; + area_dst = tmp_area; + + printf("userfaults:"); + for (cpu = 0; cpu < nr_cpus; cpu++) + printf(" %lu", userfaults[cpu]); + printf("\n"); + } + + return 0; +} + +int main(int argc, char **argv) +{ + if (argc < 3) + fprintf(stderr, "Usage: <MiB> <bounces>\n"), exit(1); + nr_cpus = sysconf(_SC_NPROCESSORS_ONLN); + page_size = sysconf(_SC_PAGE_SIZE); + if ((unsigned long) area_count(NULL, 0) + sizeof(unsigned long long) > + page_size) + fprintf(stderr, "Impossible to run this test\n"), exit(2); + nr_pages_per_cpu = atol(argv[1]) * 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[2]); + if (bounces <= 0) { + fprintf(stderr, "invalid bounces\n"); + fprintf(stderr, "Usage: <MiB> <bounces>\n"), exit(1); + } + nr_pages = nr_pages_per_cpu * nr_cpus; + printf("nr_pages: %lu, nr_pages_per_cpu: %lu\n", + nr_pages, nr_pages_per_cpu); + return userfaultfd_stress(); +} |