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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Stress userfaultfd syscall.4 *5 * Copyright (C) 2015 Red Hat, Inc.6 *7 * This test allocates two virtual areas and bounces the physical8 * memory across the two virtual areas (from area_src to area_dst)9 * using userfaultfd.10 *11 * There are three threads running per CPU:12 *13 * 1) one per-CPU thread takes a per-page pthread_mutex in a random14 * page of the area_dst (while the physical page may still be in15 * area_src), and increments a per-page counter in the same page,16 * and checks its value against a verification region.17 *18 * 2) another per-CPU thread handles the userfaults generated by19 * thread 1 above. userfaultfd blocking reads or poll() modes are20 * exercised interleaved.21 *22 * 3) one last per-CPU thread transfers the memory in the background23 * at maximum bandwidth (if not already transferred by thread24 * 2). Each cpu thread takes cares of transferring a portion of the25 * area.26 *27 * When all threads of type 3 completed the transfer, one bounce is28 * complete. area_src and area_dst are then swapped. All threads are29 * respawned and so the bounce is immediately restarted in the30 * opposite direction.31 *32 * per-CPU threads 1 by triggering userfaults inside33 * pthread_mutex_lock will also verify the atomicity of the memory34 * transfer (UFFDIO_COPY).35 */36#include <asm-generic/unistd.h>37#include "uffd-common.h"38 39uint64_t features;40 41#define BOUNCE_RANDOM (1<<0)42#define BOUNCE_RACINGFAULTS (1<<1)43#define BOUNCE_VERIFY (1<<2)44#define BOUNCE_POLL (1<<3)45static int bounces;46 47/* exercise the test_uffdio_*_eexist every ALARM_INTERVAL_SECS */48#define ALARM_INTERVAL_SECS 1049static char *zeropage;50pthread_attr_t attr;51 52#define swap(a, b) \53 do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)54 55const char *examples =56 "# Run anonymous memory test on 100MiB region with 99999 bounces:\n"57 "./uffd-stress anon 100 99999\n\n"58 "# Run share memory test on 1GiB region with 99 bounces:\n"59 "./uffd-stress shmem 1000 99\n\n"60 "# Run hugetlb memory test on 256MiB region with 50 bounces:\n"61 "./uffd-stress hugetlb 256 50\n\n"62 "# Run the same hugetlb test but using private file:\n"63 "./uffd-stress hugetlb-private 256 50\n\n"64 "# 10MiB-~6GiB 999 bounces anonymous test, "65 "continue forever unless an error triggers\n"66 "while ./uffd-stress anon $[RANDOM % 6000 + 10] 999; do true; done\n\n";67 68static void usage(void)69{70 fprintf(stderr, "\nUsage: ./uffd-stress <test type> <MiB> <bounces>\n\n");71 fprintf(stderr, "Supported <test type>: anon, hugetlb, "72 "hugetlb-private, shmem, shmem-private\n\n");73 fprintf(stderr, "Examples:\n\n");74 fprintf(stderr, "%s", examples);75 exit(1);76}77 78static void uffd_stats_reset(struct uffd_args *args, unsigned long n_cpus)79{80 int i;81 82 for (i = 0; i < n_cpus; i++) {83 args[i].cpu = i;84 args[i].apply_wp = test_uffdio_wp;85 args[i].missing_faults = 0;86 args[i].wp_faults = 0;87 args[i].minor_faults = 0;88 }89}90 91static void *locking_thread(void *arg)92{93 unsigned long cpu = (unsigned long) arg;94 unsigned long page_nr;95 unsigned long long count;96 97 if (!(bounces & BOUNCE_RANDOM)) {98 page_nr = -bounces;99 if (!(bounces & BOUNCE_RACINGFAULTS))100 page_nr += cpu * nr_pages_per_cpu;101 }102 103 while (!finished) {104 if (bounces & BOUNCE_RANDOM) {105 if (getrandom(&page_nr, sizeof(page_nr), 0) != sizeof(page_nr))106 err("getrandom failed");107 } else108 page_nr += 1;109 page_nr %= nr_pages;110 pthread_mutex_lock(area_mutex(area_dst, page_nr));111 count = *area_count(area_dst, page_nr);112 if (count != count_verify[page_nr])113 err("page_nr %lu memory corruption %llu %llu",114 page_nr, count, count_verify[page_nr]);115 count++;116 *area_count(area_dst, page_nr) = count_verify[page_nr] = count;117 pthread_mutex_unlock(area_mutex(area_dst, page_nr));118 }119 120 return NULL;121}122 123static int copy_page_retry(int ufd, unsigned long offset)124{125 return __copy_page(ufd, offset, true, test_uffdio_wp);126}127 128pthread_mutex_t uffd_read_mutex = PTHREAD_MUTEX_INITIALIZER;129 130static void *uffd_read_thread(void *arg)131{132 struct uffd_args *args = (struct uffd_args *)arg;133 struct uffd_msg msg;134 135 pthread_mutex_unlock(&uffd_read_mutex);136 /* from here cancellation is ok */137 138 for (;;) {139 if (uffd_read_msg(uffd, &msg))140 continue;141 uffd_handle_page_fault(&msg, args);142 }143 144 return NULL;145}146 147static void *background_thread(void *arg)148{149 unsigned long cpu = (unsigned long) arg;150 unsigned long page_nr, start_nr, mid_nr, end_nr;151 152 start_nr = cpu * nr_pages_per_cpu;153 end_nr = (cpu+1) * nr_pages_per_cpu;154 mid_nr = (start_nr + end_nr) / 2;155 156 /* Copy the first half of the pages */157 for (page_nr = start_nr; page_nr < mid_nr; page_nr++)158 copy_page_retry(uffd, page_nr * page_size);159 160 /*161 * If we need to test uffd-wp, set it up now. Then we'll have162 * at least the first half of the pages mapped already which163 * can be write-protected for testing164 */165 if (test_uffdio_wp)166 wp_range(uffd, (unsigned long)area_dst + start_nr * page_size,167 nr_pages_per_cpu * page_size, true);168 169 /*170 * Continue the 2nd half of the page copying, handling write171 * protection faults if any172 */173 for (page_nr = mid_nr; page_nr < end_nr; page_nr++)174 copy_page_retry(uffd, page_nr * page_size);175 176 return NULL;177}178 179static int stress(struct uffd_args *args)180{181 unsigned long cpu;182 pthread_t locking_threads[nr_cpus];183 pthread_t uffd_threads[nr_cpus];184 pthread_t background_threads[nr_cpus];185 186 finished = 0;187 for (cpu = 0; cpu < nr_cpus; cpu++) {188 if (pthread_create(&locking_threads[cpu], &attr,189 locking_thread, (void *)cpu))190 return 1;191 if (bounces & BOUNCE_POLL) {192 if (pthread_create(&uffd_threads[cpu], &attr, uffd_poll_thread, &args[cpu]))193 err("uffd_poll_thread create");194 } else {195 if (pthread_create(&uffd_threads[cpu], &attr,196 uffd_read_thread,197 (void *)&args[cpu]))198 return 1;199 pthread_mutex_lock(&uffd_read_mutex);200 }201 if (pthread_create(&background_threads[cpu], &attr,202 background_thread, (void *)cpu))203 return 1;204 }205 for (cpu = 0; cpu < nr_cpus; cpu++)206 if (pthread_join(background_threads[cpu], NULL))207 return 1;208 209 /*210 * Be strict and immediately zap area_src, the whole area has211 * been transferred already by the background treads. The212 * area_src could then be faulted in a racy way by still213 * running uffdio_threads reading zeropages after we zapped214 * area_src (but they're guaranteed to get -EEXIST from215 * UFFDIO_COPY without writing zero pages into area_dst216 * because the background threads already completed).217 */218 uffd_test_ops->release_pages(area_src);219 220 finished = 1;221 for (cpu = 0; cpu < nr_cpus; cpu++)222 if (pthread_join(locking_threads[cpu], NULL))223 return 1;224 225 for (cpu = 0; cpu < nr_cpus; cpu++) {226 char c;227 if (bounces & BOUNCE_POLL) {228 if (write(pipefd[cpu*2+1], &c, 1) != 1)229 err("pipefd write error");230 if (pthread_join(uffd_threads[cpu],231 (void *)&args[cpu]))232 return 1;233 } else {234 if (pthread_cancel(uffd_threads[cpu]))235 return 1;236 if (pthread_join(uffd_threads[cpu], NULL))237 return 1;238 }239 }240 241 return 0;242}243 244static int userfaultfd_stress(void)245{246 void *area;247 unsigned long nr;248 struct uffd_args args[nr_cpus];249 uint64_t mem_size = nr_pages * page_size;250 int flags = 0;251 252 memset(args, 0, sizeof(struct uffd_args) * nr_cpus);253 254 if (features & UFFD_FEATURE_WP_UNPOPULATED && test_type == TEST_ANON)255 flags = UFFD_FEATURE_WP_UNPOPULATED;256 257 if (uffd_test_ctx_init(flags, NULL))258 err("context init failed");259 260 if (posix_memalign(&area, page_size, page_size))261 err("out of memory");262 zeropage = area;263 bzero(zeropage, page_size);264 265 pthread_mutex_lock(&uffd_read_mutex);266 267 pthread_attr_init(&attr);268 pthread_attr_setstacksize(&attr, 16*1024*1024);269 270 while (bounces--) {271 printf("bounces: %d, mode:", bounces);272 if (bounces & BOUNCE_RANDOM)273 printf(" rnd");274 if (bounces & BOUNCE_RACINGFAULTS)275 printf(" racing");276 if (bounces & BOUNCE_VERIFY)277 printf(" ver");278 if (bounces & BOUNCE_POLL)279 printf(" poll");280 else281 printf(" read");282 printf(", ");283 fflush(stdout);284 285 if (bounces & BOUNCE_POLL)286 fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);287 else288 fcntl(uffd, F_SETFL, uffd_flags & ~O_NONBLOCK);289 290 /* register */291 if (uffd_register(uffd, area_dst, mem_size,292 true, test_uffdio_wp, false))293 err("register failure");294 295 if (area_dst_alias) {296 if (uffd_register(uffd, area_dst_alias, mem_size,297 true, test_uffdio_wp, false))298 err("register failure alias");299 }300 301 /*302 * The madvise done previously isn't enough: some303 * uffd_thread could have read userfaults (one of304 * those already resolved by the background thread)305 * and it may be in the process of calling306 * UFFDIO_COPY. UFFDIO_COPY will read the zapped307 * area_src and it would map a zero page in it (of308 * course such a UFFDIO_COPY is perfectly safe as it'd309 * return -EEXIST). The problem comes at the next310 * bounce though: that racing UFFDIO_COPY would311 * generate zeropages in the area_src, so invalidating312 * the previous MADV_DONTNEED. Without this additional313 * MADV_DONTNEED those zeropages leftovers in the314 * area_src would lead to -EEXIST failure during the315 * next bounce, effectively leaving a zeropage in the316 * area_dst.317 *318 * Try to comment this out madvise to see the memory319 * corruption being caught pretty quick.320 *321 * khugepaged is also inhibited to collapse THP after322 * MADV_DONTNEED only after the UFFDIO_REGISTER, so it's323 * required to MADV_DONTNEED here.324 */325 uffd_test_ops->release_pages(area_dst);326 327 uffd_stats_reset(args, nr_cpus);328 329 /* bounce pass */330 if (stress(args)) {331 uffd_test_ctx_clear();332 return 1;333 }334 335 /* Clear all the write protections if there is any */336 if (test_uffdio_wp)337 wp_range(uffd, (unsigned long)area_dst,338 nr_pages * page_size, false);339 340 /* unregister */341 if (uffd_unregister(uffd, area_dst, mem_size))342 err("unregister failure");343 if (area_dst_alias) {344 if (uffd_unregister(uffd, area_dst_alias, mem_size))345 err("unregister failure alias");346 }347 348 /* verification */349 if (bounces & BOUNCE_VERIFY)350 for (nr = 0; nr < nr_pages; nr++)351 if (*area_count(area_dst, nr) != count_verify[nr])352 err("error area_count %llu %llu %lu\n",353 *area_count(area_src, nr),354 count_verify[nr], nr);355 356 /* prepare next bounce */357 swap(area_src, area_dst);358 359 swap(area_src_alias, area_dst_alias);360 361 uffd_stats_report(args, nr_cpus);362 }363 uffd_test_ctx_clear();364 365 return 0;366}367 368static void set_test_type(const char *type)369{370 if (!strcmp(type, "anon")) {371 test_type = TEST_ANON;372 uffd_test_ops = &anon_uffd_test_ops;373 } else if (!strcmp(type, "hugetlb")) {374 test_type = TEST_HUGETLB;375 uffd_test_ops = &hugetlb_uffd_test_ops;376 map_shared = true;377 } else if (!strcmp(type, "hugetlb-private")) {378 test_type = TEST_HUGETLB;379 uffd_test_ops = &hugetlb_uffd_test_ops;380 } else if (!strcmp(type, "shmem")) {381 map_shared = true;382 test_type = TEST_SHMEM;383 uffd_test_ops = &shmem_uffd_test_ops;384 } else if (!strcmp(type, "shmem-private")) {385 test_type = TEST_SHMEM;386 uffd_test_ops = &shmem_uffd_test_ops;387 }388}389 390static void parse_test_type_arg(const char *raw_type)391{392 set_test_type(raw_type);393 394 if (!test_type)395 err("failed to parse test type argument: '%s'", raw_type);396 397 if (test_type == TEST_HUGETLB)398 page_size = default_huge_page_size();399 else400 page_size = sysconf(_SC_PAGE_SIZE);401 402 if (!page_size)403 err("Unable to determine page size");404 if ((unsigned long) area_count(NULL, 0) + sizeof(unsigned long long) * 2405 > page_size)406 err("Impossible to run this test");407 408 /*409 * Whether we can test certain features depends not just on test type,410 * but also on whether or not this particular kernel supports the411 * feature.412 */413 414 if (uffd_get_features(&features))415 err("failed to get available features");416 417 test_uffdio_wp = test_uffdio_wp &&418 (features & UFFD_FEATURE_PAGEFAULT_FLAG_WP);419 420 if (test_type != TEST_ANON && !(features & UFFD_FEATURE_WP_HUGETLBFS_SHMEM))421 test_uffdio_wp = false;422 423 close(uffd);424 uffd = -1;425}426 427static void sigalrm(int sig)428{429 if (sig != SIGALRM)430 abort();431 test_uffdio_copy_eexist = true;432 alarm(ALARM_INTERVAL_SECS);433}434 435int main(int argc, char **argv)436{437 size_t bytes;438 439 if (argc < 4)440 usage();441 442 if (signal(SIGALRM, sigalrm) == SIG_ERR)443 err("failed to arm SIGALRM");444 alarm(ALARM_INTERVAL_SECS);445 446 parse_test_type_arg(argv[1]);447 bytes = atol(argv[2]) * 1024 * 1024;448 449 if (test_type == TEST_HUGETLB &&450 get_free_hugepages() < bytes / page_size) {451 printf("skip: Skipping userfaultfd... not enough hugepages\n");452 return KSFT_SKIP;453 }454 455 nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);456 457 nr_pages_per_cpu = bytes / page_size / nr_cpus;458 if (!nr_pages_per_cpu) {459 _err("invalid MiB");460 usage();461 }462 463 bounces = atoi(argv[3]);464 if (bounces <= 0) {465 _err("invalid bounces");466 usage();467 }468 nr_pages = nr_pages_per_cpu * nr_cpus;469 470 printf("nr_pages: %lu, nr_pages_per_cpu: %lu\n",471 nr_pages, nr_pages_per_cpu);472 return userfaultfd_stress();473}474