1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright 2020 Google LLC
4 */
5 #define _GNU_SOURCE
6
7 #include <errno.h>
8 #include <stdlib.h>
9 #include <stdio.h>
10 #include <string.h>
11 #include <sys/mman.h>
12 #include <time.h>
13 #include <stdbool.h>
14
15 #include "../kselftest.h"
16
17 #define EXPECT_SUCCESS 0
18 #define EXPECT_FAILURE 1
19 #define NON_OVERLAPPING 0
20 #define OVERLAPPING 1
21 #define NS_PER_SEC 1000000000ULL
22 #define VALIDATION_DEFAULT_THRESHOLD 4 /* 4MB */
23 #define VALIDATION_NO_THRESHOLD 0 /* Verify the entire region */
24
25 #define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
26
27 struct config {
28 unsigned long long src_alignment;
29 unsigned long long dest_alignment;
30 unsigned long long region_size;
31 int overlapping;
32 };
33
34 struct test {
35 const char *name;
36 struct config config;
37 int expect_failure;
38 };
39
40 enum {
41 _1KB = 1ULL << 10, /* 1KB -> not page aligned */
42 _4KB = 4ULL << 10,
43 _8KB = 8ULL << 10,
44 _1MB = 1ULL << 20,
45 _2MB = 2ULL << 20,
46 _4MB = 4ULL << 20,
47 _1GB = 1ULL << 30,
48 _2GB = 2ULL << 30,
49 PMD = _2MB,
50 PUD = _1GB,
51 };
52
53 #define PTE page_size
54
55 #define MAKE_TEST(source_align, destination_align, size, \
56 overlaps, should_fail, test_name) \
57 (struct test){ \
58 .name = test_name, \
59 .config = { \
60 .src_alignment = source_align, \
61 .dest_alignment = destination_align, \
62 .region_size = size, \
63 .overlapping = overlaps, \
64 }, \
65 .expect_failure = should_fail \
66 }
67
68 /*
69 * Returns false if the requested remap region overlaps with an
70 * existing mapping (e.g text, stack) else returns true.
71 */
is_remap_region_valid(void * addr,unsigned long long size)72 static bool is_remap_region_valid(void *addr, unsigned long long size)
73 {
74 void *remap_addr = NULL;
75 bool ret = true;
76
77 /* Use MAP_FIXED_NOREPLACE flag to ensure region is not mapped */
78 remap_addr = mmap(addr, size, PROT_READ | PROT_WRITE,
79 MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED,
80 -1, 0);
81
82 if (remap_addr == MAP_FAILED) {
83 if (errno == EEXIST)
84 ret = false;
85 } else {
86 munmap(remap_addr, size);
87 }
88
89 return ret;
90 }
91
92 /* Returns mmap_min_addr sysctl tunable from procfs */
get_mmap_min_addr(void)93 static unsigned long long get_mmap_min_addr(void)
94 {
95 FILE *fp;
96 int n_matched;
97 static unsigned long long addr;
98
99 if (addr)
100 return addr;
101
102 fp = fopen("/proc/sys/vm/mmap_min_addr", "r");
103 if (fp == NULL) {
104 ksft_print_msg("Failed to open /proc/sys/vm/mmap_min_addr: %s\n",
105 strerror(errno));
106 exit(KSFT_SKIP);
107 }
108
109 n_matched = fscanf(fp, "%llu", &addr);
110 if (n_matched != 1) {
111 ksft_print_msg("Failed to read /proc/sys/vm/mmap_min_addr: %s\n",
112 strerror(errno));
113 fclose(fp);
114 exit(KSFT_SKIP);
115 }
116
117 fclose(fp);
118 return addr;
119 }
120
121 /*
122 * Using /proc/self/maps, assert that the specified address range is contained
123 * within a single mapping.
124 */
is_range_mapped(FILE * maps_fp,void * start,void * end)125 static bool is_range_mapped(FILE *maps_fp, void *start, void *end)
126 {
127 char *line = NULL;
128 size_t len = 0;
129 bool success = false;
130
131 rewind(maps_fp);
132
133 while (getline(&line, &len, maps_fp) != -1) {
134 char *first = strtok(line, "- ");
135 void *first_val = (void *)strtol(first, NULL, 16);
136 char *second = strtok(NULL, "- ");
137 void *second_val = (void *) strtol(second, NULL, 16);
138
139 if (first_val <= start && second_val >= end) {
140 success = true;
141 break;
142 }
143 }
144
145 return success;
146 }
147
148 /*
149 * This test validates that merge is called when expanding a mapping.
150 * Mapping containing three pages is created, middle page is unmapped
151 * and then the mapping containing the first page is expanded so that
152 * it fills the created hole. The two parts should merge creating
153 * single mapping with three pages.
154 */
mremap_expand_merge(FILE * maps_fp,unsigned long page_size)155 static void mremap_expand_merge(FILE *maps_fp, unsigned long page_size)
156 {
157 char *test_name = "mremap expand merge";
158 bool success = false;
159 char *remap, *start;
160
161 start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
162 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
163
164 if (start == MAP_FAILED) {
165 ksft_print_msg("mmap failed: %s\n", strerror(errno));
166 goto out;
167 }
168
169 munmap(start + page_size, page_size);
170 remap = mremap(start, page_size, 2 * page_size, 0);
171 if (remap == MAP_FAILED) {
172 ksft_print_msg("mremap failed: %s\n", strerror(errno));
173 munmap(start, page_size);
174 munmap(start + 2 * page_size, page_size);
175 goto out;
176 }
177
178 success = is_range_mapped(maps_fp, start, start + 3 * page_size);
179 munmap(start, 3 * page_size);
180
181 out:
182 if (success)
183 ksft_test_result_pass("%s\n", test_name);
184 else
185 ksft_test_result_fail("%s\n", test_name);
186 }
187
188 /*
189 * Similar to mremap_expand_merge() except instead of removing the middle page,
190 * we remove the last then attempt to remap offset from the second page. This
191 * should result in the mapping being restored to its former state.
192 */
mremap_expand_merge_offset(FILE * maps_fp,unsigned long page_size)193 static void mremap_expand_merge_offset(FILE *maps_fp, unsigned long page_size)
194 {
195
196 char *test_name = "mremap expand merge offset";
197 bool success = false;
198 char *remap, *start;
199
200 start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
201 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
202
203 if (start == MAP_FAILED) {
204 ksft_print_msg("mmap failed: %s\n", strerror(errno));
205 goto out;
206 }
207
208 /* Unmap final page to ensure we have space to expand. */
209 munmap(start + 2 * page_size, page_size);
210 remap = mremap(start + page_size, page_size, 2 * page_size, 0);
211 if (remap == MAP_FAILED) {
212 ksft_print_msg("mremap failed: %s\n", strerror(errno));
213 munmap(start, 2 * page_size);
214 goto out;
215 }
216
217 success = is_range_mapped(maps_fp, start, start + 3 * page_size);
218 munmap(start, 3 * page_size);
219
220 out:
221 if (success)
222 ksft_test_result_pass("%s\n", test_name);
223 else
224 ksft_test_result_fail("%s\n", test_name);
225 }
226
227 /*
228 * Returns the start address of the mapping on success, else returns
229 * NULL on failure.
230 */
get_source_mapping(struct config c)231 static void *get_source_mapping(struct config c)
232 {
233 unsigned long long addr = 0ULL;
234 void *src_addr = NULL;
235 unsigned long long mmap_min_addr;
236
237 mmap_min_addr = get_mmap_min_addr();
238
239 retry:
240 addr += c.src_alignment;
241 if (addr < mmap_min_addr)
242 goto retry;
243
244 src_addr = mmap((void *) addr, c.region_size, PROT_READ | PROT_WRITE,
245 MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED,
246 -1, 0);
247 if (src_addr == MAP_FAILED) {
248 if (errno == EPERM || errno == EEXIST)
249 goto retry;
250 goto error;
251 }
252 /*
253 * Check that the address is aligned to the specified alignment.
254 * Addresses which have alignments that are multiples of that
255 * specified are not considered valid. For instance, 1GB address is
256 * 2MB-aligned, however it will not be considered valid for a
257 * requested alignment of 2MB. This is done to reduce coincidental
258 * alignment in the tests.
259 */
260 if (((unsigned long long) src_addr & (c.src_alignment - 1)) ||
261 !((unsigned long long) src_addr & c.src_alignment)) {
262 munmap(src_addr, c.region_size);
263 goto retry;
264 }
265
266 if (!src_addr)
267 goto error;
268
269 return src_addr;
270 error:
271 ksft_print_msg("Failed to map source region: %s\n",
272 strerror(errno));
273 return NULL;
274 }
275
276 /* Returns the time taken for the remap on success else returns -1. */
remap_region(struct config c,unsigned int threshold_mb,char pattern_seed)277 static long long remap_region(struct config c, unsigned int threshold_mb,
278 char pattern_seed)
279 {
280 void *addr, *src_addr, *dest_addr;
281 unsigned long long i;
282 struct timespec t_start = {0, 0}, t_end = {0, 0};
283 long long start_ns, end_ns, align_mask, ret, offset;
284 unsigned long long threshold;
285
286 if (threshold_mb == VALIDATION_NO_THRESHOLD)
287 threshold = c.region_size;
288 else
289 threshold = MIN(threshold_mb * _1MB, c.region_size);
290
291 src_addr = get_source_mapping(c);
292 if (!src_addr) {
293 ret = -1;
294 goto out;
295 }
296
297 /* Set byte pattern */
298 srand(pattern_seed);
299 for (i = 0; i < threshold; i++)
300 memset((char *) src_addr + i, (char) rand(), 1);
301
302 /* Mask to zero out lower bits of address for alignment */
303 align_mask = ~(c.dest_alignment - 1);
304 /* Offset of destination address from the end of the source region */
305 offset = (c.overlapping) ? -c.dest_alignment : c.dest_alignment;
306 addr = (void *) (((unsigned long long) src_addr + c.region_size
307 + offset) & align_mask);
308
309 /* See comment in get_source_mapping() */
310 if (!((unsigned long long) addr & c.dest_alignment))
311 addr = (void *) ((unsigned long long) addr | c.dest_alignment);
312
313 /* Don't destroy existing mappings unless expected to overlap */
314 while (!is_remap_region_valid(addr, c.region_size) && !c.overlapping) {
315 /* Check for unsigned overflow */
316 if (addr + c.dest_alignment < addr) {
317 ksft_print_msg("Couldn't find a valid region to remap to\n");
318 ret = -1;
319 goto out;
320 }
321 addr += c.dest_alignment;
322 }
323
324 clock_gettime(CLOCK_MONOTONIC, &t_start);
325 dest_addr = mremap(src_addr, c.region_size, c.region_size,
326 MREMAP_MAYMOVE|MREMAP_FIXED, (char *) addr);
327 clock_gettime(CLOCK_MONOTONIC, &t_end);
328
329 if (dest_addr == MAP_FAILED) {
330 ksft_print_msg("mremap failed: %s\n", strerror(errno));
331 ret = -1;
332 goto clean_up_src;
333 }
334
335 /* Verify byte pattern after remapping */
336 srand(pattern_seed);
337 for (i = 0; i < threshold; i++) {
338 char c = (char) rand();
339
340 if (((char *) dest_addr)[i] != c) {
341 ksft_print_msg("Data after remap doesn't match at offset %d\n",
342 i);
343 ksft_print_msg("Expected: %#x\t Got: %#x\n", c & 0xff,
344 ((char *) dest_addr)[i] & 0xff);
345 ret = -1;
346 goto clean_up_dest;
347 }
348 }
349
350 start_ns = t_start.tv_sec * NS_PER_SEC + t_start.tv_nsec;
351 end_ns = t_end.tv_sec * NS_PER_SEC + t_end.tv_nsec;
352 ret = end_ns - start_ns;
353
354 /*
355 * Since the destination address is specified using MREMAP_FIXED, subsequent
356 * mremap will unmap any previous mapping at the address range specified by
357 * dest_addr and region_size. This significantly affects the remap time of
358 * subsequent tests. So we clean up mappings after each test.
359 */
360 clean_up_dest:
361 munmap(dest_addr, c.region_size);
362 clean_up_src:
363 munmap(src_addr, c.region_size);
364 out:
365 return ret;
366 }
367
run_mremap_test_case(struct test test_case,int * failures,unsigned int threshold_mb,unsigned int pattern_seed)368 static void run_mremap_test_case(struct test test_case, int *failures,
369 unsigned int threshold_mb,
370 unsigned int pattern_seed)
371 {
372 long long remap_time = remap_region(test_case.config, threshold_mb,
373 pattern_seed);
374
375 if (remap_time < 0) {
376 if (test_case.expect_failure)
377 ksft_test_result_xfail("%s\n\tExpected mremap failure\n",
378 test_case.name);
379 else {
380 ksft_test_result_fail("%s\n", test_case.name);
381 *failures += 1;
382 }
383 } else {
384 /*
385 * Comparing mremap time is only applicable if entire region
386 * was faulted in.
387 */
388 if (threshold_mb == VALIDATION_NO_THRESHOLD ||
389 test_case.config.region_size <= threshold_mb * _1MB)
390 ksft_test_result_pass("%s\n\tmremap time: %12lldns\n",
391 test_case.name, remap_time);
392 else
393 ksft_test_result_pass("%s\n", test_case.name);
394 }
395 }
396
usage(const char * cmd)397 static void usage(const char *cmd)
398 {
399 fprintf(stderr,
400 "Usage: %s [[-t <threshold_mb>] [-p <pattern_seed>]]\n"
401 "-t\t only validate threshold_mb of the remapped region\n"
402 " \t if 0 is supplied no threshold is used; all tests\n"
403 " \t are run and remapped regions validated fully.\n"
404 " \t The default threshold used is 4MB.\n"
405 "-p\t provide a seed to generate the random pattern for\n"
406 " \t validating the remapped region.\n", cmd);
407 }
408
parse_args(int argc,char ** argv,unsigned int * threshold_mb,unsigned int * pattern_seed)409 static int parse_args(int argc, char **argv, unsigned int *threshold_mb,
410 unsigned int *pattern_seed)
411 {
412 const char *optstr = "t:p:";
413 int opt;
414
415 while ((opt = getopt(argc, argv, optstr)) != -1) {
416 switch (opt) {
417 case 't':
418 *threshold_mb = atoi(optarg);
419 break;
420 case 'p':
421 *pattern_seed = atoi(optarg);
422 break;
423 default:
424 usage(argv[0]);
425 return -1;
426 }
427 }
428
429 if (optind < argc) {
430 usage(argv[0]);
431 return -1;
432 }
433
434 return 0;
435 }
436
437 #define MAX_TEST 13
438 #define MAX_PERF_TEST 3
main(int argc,char ** argv)439 int main(int argc, char **argv)
440 {
441 int failures = 0;
442 int i, run_perf_tests;
443 unsigned int threshold_mb = VALIDATION_DEFAULT_THRESHOLD;
444 unsigned int pattern_seed;
445 int num_expand_tests = 2;
446 struct test test_cases[MAX_TEST];
447 struct test perf_test_cases[MAX_PERF_TEST];
448 int page_size;
449 time_t t;
450 FILE *maps_fp;
451
452 pattern_seed = (unsigned int) time(&t);
453
454 if (parse_args(argc, argv, &threshold_mb, &pattern_seed) < 0)
455 exit(EXIT_FAILURE);
456
457 ksft_print_msg("Test configs:\n\tthreshold_mb=%u\n\tpattern_seed=%u\n\n",
458 threshold_mb, pattern_seed);
459
460 page_size = sysconf(_SC_PAGESIZE);
461
462 /* Expected mremap failures */
463 test_cases[0] = MAKE_TEST(page_size, page_size, page_size,
464 OVERLAPPING, EXPECT_FAILURE,
465 "mremap - Source and Destination Regions Overlapping");
466
467 test_cases[1] = MAKE_TEST(page_size, page_size/4, page_size,
468 NON_OVERLAPPING, EXPECT_FAILURE,
469 "mremap - Destination Address Misaligned (1KB-aligned)");
470 test_cases[2] = MAKE_TEST(page_size/4, page_size, page_size,
471 NON_OVERLAPPING, EXPECT_FAILURE,
472 "mremap - Source Address Misaligned (1KB-aligned)");
473
474 /* Src addr PTE aligned */
475 test_cases[3] = MAKE_TEST(PTE, PTE, PTE * 2,
476 NON_OVERLAPPING, EXPECT_SUCCESS,
477 "8KB mremap - Source PTE-aligned, Destination PTE-aligned");
478
479 /* Src addr 1MB aligned */
480 test_cases[4] = MAKE_TEST(_1MB, PTE, _2MB, NON_OVERLAPPING, EXPECT_SUCCESS,
481 "2MB mremap - Source 1MB-aligned, Destination PTE-aligned");
482 test_cases[5] = MAKE_TEST(_1MB, _1MB, _2MB, NON_OVERLAPPING, EXPECT_SUCCESS,
483 "2MB mremap - Source 1MB-aligned, Destination 1MB-aligned");
484
485 /* Src addr PMD aligned */
486 test_cases[6] = MAKE_TEST(PMD, PTE, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
487 "4MB mremap - Source PMD-aligned, Destination PTE-aligned");
488 test_cases[7] = MAKE_TEST(PMD, _1MB, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
489 "4MB mremap - Source PMD-aligned, Destination 1MB-aligned");
490 test_cases[8] = MAKE_TEST(PMD, PMD, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
491 "4MB mremap - Source PMD-aligned, Destination PMD-aligned");
492
493 /* Src addr PUD aligned */
494 test_cases[9] = MAKE_TEST(PUD, PTE, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
495 "2GB mremap - Source PUD-aligned, Destination PTE-aligned");
496 test_cases[10] = MAKE_TEST(PUD, _1MB, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
497 "2GB mremap - Source PUD-aligned, Destination 1MB-aligned");
498 test_cases[11] = MAKE_TEST(PUD, PMD, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
499 "2GB mremap - Source PUD-aligned, Destination PMD-aligned");
500 test_cases[12] = MAKE_TEST(PUD, PUD, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
501 "2GB mremap - Source PUD-aligned, Destination PUD-aligned");
502
503 perf_test_cases[0] = MAKE_TEST(page_size, page_size, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
504 "1GB mremap - Source PTE-aligned, Destination PTE-aligned");
505 /*
506 * mremap 1GB region - Page table level aligned time
507 * comparison.
508 */
509 perf_test_cases[1] = MAKE_TEST(PMD, PMD, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
510 "1GB mremap - Source PMD-aligned, Destination PMD-aligned");
511 perf_test_cases[2] = MAKE_TEST(PUD, PUD, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
512 "1GB mremap - Source PUD-aligned, Destination PUD-aligned");
513
514 run_perf_tests = (threshold_mb == VALIDATION_NO_THRESHOLD) ||
515 (threshold_mb * _1MB >= _1GB);
516
517 ksft_set_plan(ARRAY_SIZE(test_cases) + (run_perf_tests ?
518 ARRAY_SIZE(perf_test_cases) : 0) + num_expand_tests);
519
520 for (i = 0; i < ARRAY_SIZE(test_cases); i++)
521 run_mremap_test_case(test_cases[i], &failures, threshold_mb,
522 pattern_seed);
523
524 maps_fp = fopen("/proc/self/maps", "r");
525
526 if (maps_fp == NULL) {
527 ksft_print_msg("Failed to read /proc/self/maps: %s\n", strerror(errno));
528 exit(KSFT_FAIL);
529 }
530
531 mremap_expand_merge(maps_fp, page_size);
532 mremap_expand_merge_offset(maps_fp, page_size);
533
534 fclose(maps_fp);
535
536 if (run_perf_tests) {
537 ksft_print_msg("\n%s\n",
538 "mremap HAVE_MOVE_PMD/PUD optimization time comparison for 1GB region:");
539 for (i = 0; i < ARRAY_SIZE(perf_test_cases); i++)
540 run_mremap_test_case(perf_test_cases[i], &failures,
541 threshold_mb, pattern_seed);
542 }
543
544 if (failures > 0)
545 ksft_exit_fail();
546 else
547 ksft_exit_pass();
548 }
549