summaryrefslogtreecommitdiffstats
path: root/tools/testing/selftests/powerpc/mm/tlbie_test.c
blob: 48344a74b2128113d936f4a34bad9cd94d45d4ca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
// SPDX-License-Identifier: GPL-2.0

/*
 * Copyright 2019, Nick Piggin, Gautham R. Shenoy, Aneesh Kumar K.V, IBM Corp.
 */

/*
 *
 * Test tlbie/mtpidr race. We have 4 threads doing flush/load/compare/store
 * sequence in a loop. The same threads also rung a context switch task
 * that does sched_yield() in loop.
 *
 * The snapshot thread mark the mmap area PROT_READ in between, make a copy
 * and copy it back to the original area. This helps us to detect if any
 * store continued to happen after we marked the memory PROT_READ.
 */

#define _GNU_SOURCE
#include <stdio.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <linux/futex.h>
#include <unistd.h>
#include <asm/unistd.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sched.h>
#include <time.h>
#include <stdarg.h>
#include <pthread.h>
#include <signal.h>
#include <sys/prctl.h>

static inline void dcbf(volatile unsigned int *addr)
{
	__asm__ __volatile__ ("dcbf %y0; sync" : : "Z"(*(unsigned char *)addr) : "memory");
}

static void err_msg(char *msg)
{

	time_t now;
	time(&now);
	printf("=================================\n");
	printf("    Error: %s\n", msg);
	printf("    %s", ctime(&now));
	printf("=================================\n");
	exit(1);
}

static char *map1;
static char *map2;
static pid_t rim_process_pid;

/*
 * A "rim-sequence" is defined to be the sequence of the following
 * operations performed on a memory word:
 *	1) FLUSH the contents of that word.
 *	2) LOAD the contents of that word.
 *	3) COMPARE the contents of that word with the content that was
 *	           previously stored at that word
 *	4) STORE new content into that word.
 *
 * The threads in this test that perform the rim-sequence are termed
 * as rim_threads.
 */

/*
 * A "corruption" is defined to be the failed COMPARE operation in a
 * rim-sequence.
 *
 * A rim_thread that detects a corruption informs about it to all the
 * other rim_threads, and the mem_snapshot thread.
 */
static volatile unsigned int corruption_found;

/*
 * This defines the maximum number of rim_threads in this test.
 *
 * The THREAD_ID_BITS denote the number of bits required
 * to represent the thread_ids [0..MAX_THREADS - 1].
 * We are being a bit paranoid here and set it to 8 bits,
 * though 6 bits suffice.
 *
 */
#define MAX_THREADS 		64
#define THREAD_ID_BITS		8
#define THREAD_ID_MASK		((1 << THREAD_ID_BITS) - 1)
static unsigned int rim_thread_ids[MAX_THREADS];
static pthread_t rim_threads[MAX_THREADS];


/*
 * Each rim_thread works on an exclusive "chunk" of size
 * RIM_CHUNK_SIZE.
 *
 * The ith rim_thread works on the ith chunk.
 *
 * The ith chunk begins at
 * map1 + (i * RIM_CHUNK_SIZE)
 */
#define RIM_CHUNK_SIZE  	1024
#define BITS_PER_BYTE 		8
#define WORD_SIZE     		(sizeof(unsigned int))
#define WORD_BITS		(WORD_SIZE * BITS_PER_BYTE)
#define WORDS_PER_CHUNK		(RIM_CHUNK_SIZE/WORD_SIZE)

static inline char *compute_chunk_start_addr(unsigned int thread_id)
{
	char *chunk_start;

	chunk_start = (char *)((unsigned long)map1 +
			       (thread_id * RIM_CHUNK_SIZE));

	return chunk_start;
}

/*
 * The "word-offset" of a word-aligned address inside a chunk, is
 * defined to be the number of words that precede the address in that
 * chunk.
 *
 * WORD_OFFSET_BITS denote the number of bits required to represent
 * the word-offsets of all the word-aligned addresses of a chunk.
 */
#define WORD_OFFSET_BITS	(__builtin_ctz(WORDS_PER_CHUNK))
#define WORD_OFFSET_MASK	((1 << WORD_OFFSET_BITS) - 1)

static inline unsigned int compute_word_offset(char *start, unsigned int *addr)
{
	unsigned int delta_bytes, ret;
	delta_bytes = (unsigned long)addr - (unsigned long)start;

	ret = delta_bytes/WORD_SIZE;

	return ret;
}

/*
 * A "sweep" is defined to be the sequential execution of the
 * rim-sequence by a rim_thread on its chunk one word at a time,
 * starting from the first word of its chunk and ending with the last
 * word of its chunk.
 *
 * Each sweep of a rim_thread is uniquely identified by a sweep_id.
 * SWEEP_ID_BITS denote the number of bits required to represent
 * the sweep_ids of rim_threads.
 *
 * As to why SWEEP_ID_BITS are computed as a function of THREAD_ID_BITS,
 * WORD_OFFSET_BITS, and WORD_BITS, see the "store-pattern" below.
 */
#define SWEEP_ID_BITS		(WORD_BITS - (THREAD_ID_BITS + WORD_OFFSET_BITS))
#define SWEEP_ID_MASK		((1 << SWEEP_ID_BITS) - 1)

/*
 * A "store-pattern" is the word-pattern that is stored into a word
 * location in the 4)STORE step of the rim-sequence.
 *
 * In the store-pattern, we shall encode:
 *
 *      - The thread-id of the rim_thread performing the store
 *        (The most significant THREAD_ID_BITS)
 *
 *      - The word-offset of the address into which the store is being
 *        performed (The next WORD_OFFSET_BITS)
 *
 *      - The sweep_id of the current sweep in which the store is
 *        being performed. (The lower SWEEP_ID_BITS)
 *
 * Store Pattern: 32 bits
 * |------------------|--------------------|---------------------------------|
 * |    Thread id     |  Word offset       |         sweep_id                |
 * |------------------|--------------------|---------------------------------|
 *    THREAD_ID_BITS     WORD_OFFSET_BITS          SWEEP_ID_BITS
 *
 * In the store pattern, the (Thread-id + Word-offset) uniquely identify the
 * address to which the store is being performed i.e,
 *    address == map1 +
 *              (Thread-id * RIM_CHUNK_SIZE) + (Word-offset * WORD_SIZE)
 *
 * And the sweep_id in the store pattern identifies the time when the
 * store was performed by the rim_thread.
 *
 * We shall use this property in the 3)COMPARE step of the
 * rim-sequence.
 */
#define SWEEP_ID_SHIFT	0
#define WORD_OFFSET_SHIFT	(SWEEP_ID_BITS)
#define THREAD_ID_SHIFT		(WORD_OFFSET_BITS + SWEEP_ID_BITS)

/*
 * Compute the store pattern for a given thread with id @tid, at
 * location @addr in the sweep identified by @sweep_id
 */
static inline unsigned int compute_store_pattern(unsigned int tid,
						 unsigned int *addr,
						 unsigned int sweep_id)
{
	unsigned int ret = 0;
	char *start = compute_chunk_start_addr(tid);
	unsigned int word_offset = compute_word_offset(start, addr);

	ret += (tid & THREAD_ID_MASK) << THREAD_ID_SHIFT;
	ret += (word_offset & WORD_OFFSET_MASK) << WORD_OFFSET_SHIFT;
	ret += (sweep_id & SWEEP_ID_MASK) << SWEEP_ID_SHIFT;
	return ret;
}

/* Extract the thread-id from the given store-pattern */
static inline unsigned int extract_tid(unsigned int pattern)
{
	unsigned int ret;

	ret = (pattern >> THREAD_ID_SHIFT) & THREAD_ID_MASK;
	return ret;
}

/* Extract the word-offset from the given store-pattern */
static inline unsigned int extract_word_offset(unsigned int pattern)
{
	unsigned int ret;

	ret = (pattern >> WORD_OFFSET_SHIFT) & WORD_OFFSET_MASK;

	return ret;
}

/* Extract the sweep-id from the given store-pattern */
static inline unsigned int extract_sweep_id(unsigned int pattern)

{
	unsigned int ret;

	ret = (pattern >> SWEEP_ID_SHIFT) & SWEEP_ID_MASK;

	return ret;
}

/************************************************************
 *                                                          *
 *          Logging the output of the verification          *
 *                                                          *
 ************************************************************/
#define LOGDIR_NAME_SIZE 100
static char logdir[LOGDIR_NAME_SIZE];

static FILE *fp[MAX_THREADS];
static const char logfilename[] ="Thread-%02d-Chunk";

static inline void start_verification_log(unsigned int tid,
					  unsigned int *addr,
					  unsigned int cur_sweep_id,
					  unsigned int prev_sweep_id)
{
	FILE *f;
	char logfile[30];
	char path[LOGDIR_NAME_SIZE + 30];
	char separator[2] = "/";
	char *chunk_start = compute_chunk_start_addr(tid);
	unsigned int size = RIM_CHUNK_SIZE;

	sprintf(logfile, logfilename, tid);
	strcpy(path, logdir);
	strcat(path, separator);
	strcat(path, logfile);
	f = fopen(path, "w");

	if (!f) {
		err_msg("Unable to create logfile\n");
	}

	fp[tid] = f;

	fprintf(f, "----------------------------------------------------------\n");
	fprintf(f, "PID                = %d\n", rim_process_pid);
	fprintf(f, "Thread id          = %02d\n", tid);
	fprintf(f, "Chunk Start Addr   = 0x%016lx\n", (unsigned long)chunk_start);
	fprintf(f, "Chunk Size         = %d\n", size);
	fprintf(f, "Next Store Addr    = 0x%016lx\n", (unsigned long)addr);
	fprintf(f, "Current sweep-id   = 0x%08x\n", cur_sweep_id);
	fprintf(f, "Previous sweep-id  = 0x%08x\n", prev_sweep_id);
	fprintf(f, "----------------------------------------------------------\n");
}

static inline void log_anamoly(unsigned int tid, unsigned int *addr,
			       unsigned int expected, unsigned int observed)
{
	FILE *f = fp[tid];

	fprintf(f, "Thread %02d: Addr 0x%lx: Expected 0x%x, Observed 0x%x\n",
	        tid, (unsigned long)addr, expected, observed);
	fprintf(f, "Thread %02d: Expected Thread id   = %02d\n", tid, extract_tid(expected));
	fprintf(f, "Thread %02d: Observed Thread id   = %02d\n", tid, extract_tid(observed));
	fprintf(f, "Thread %02d: Expected Word offset = %03d\n", tid, extract_word_offset(expected));
	fprintf(f, "Thread %02d: Observed Word offset = %03d\n", tid, extract_word_offset(observed));
	fprintf(f, "Thread %02d: Expected sweep-id    = 0x%x\n", tid, extract_sweep_id(expected));
	fprintf(f, "Thread %02d: Observed sweep-id    = 0x%x\n", tid, extract_sweep_id(observed));
	fprintf(f, "----------------------------------------------------------\n");
}

static inline void end_verification_log(unsigned int tid, unsigned nr_anamolies)
{
	FILE *f = fp[tid];
	char logfile[30];
	char path[LOGDIR_NAME_SIZE + 30];
	char separator[] = "/";

	fclose(f);

	if (nr_anamolies == 0) {
		remove(path);
		return;
	}

	sprintf(logfile, logfilename, tid);
	strcpy(path, logdir);
	strcat(path, separator);
	strcat(path, logfile);

	printf("Thread %02d chunk has %d corrupted words. For details check %s\n",
		tid, nr_anamolies, path);
}

/*
 * When a COMPARE step of a rim-sequence fails, the rim_thread informs
 * everyone else via the shared_memory pointed to by
 * corruption_found variable. On seeing this, every thread verifies the
 * content of its chunk as follows.
 *
 * Suppose a thread identified with @tid was about to store (but not
 * yet stored) to @next_store_addr in its current sweep identified
 * @cur_sweep_id. Let @prev_sweep_id indicate the previous sweep_id.
 *
 * This implies that for all the addresses @addr < @next_store_addr,
 * Thread @tid has already performed a store as part of its current
 * sweep. Hence we expect the content of such @addr to be:
 *    |-------------------------------------------------|
 *    | tid   | word_offset(addr) |    cur_sweep_id     |
 *    |-------------------------------------------------|
 *
 * Since Thread @tid is yet to perform stores on address
 * @next_store_addr and above, we expect the content of such an
 * address @addr to be:
 *    |-------------------------------------------------|
 *    | tid   | word_offset(addr) |    prev_sweep_id    |
 *    |-------------------------------------------------|
 *
 * The verifier function @verify_chunk does this verification and logs
 * any anamolies that it finds.
 */
static void verify_chunk(unsigned int tid, unsigned int *next_store_addr,
		  unsigned int cur_sweep_id,
		  unsigned int prev_sweep_id)
{
	unsigned int *iter_ptr;
	unsigned int size = RIM_CHUNK_SIZE;
	unsigned int expected;
	unsigned int observed;
	char *chunk_start = compute_chunk_start_addr(tid);

	int nr_anamolies = 0;

	start_verification_log(tid, next_store_addr,
			       cur_sweep_id, prev_sweep_id);

	for (iter_ptr = (unsigned int *)chunk_start;
	     (unsigned long)iter_ptr < (unsigned long)chunk_start + size;
	     iter_ptr++) {
		unsigned int expected_sweep_id;

		if (iter_ptr < next_store_addr) {
			expected_sweep_id = cur_sweep_id;
		} else {
			expected_sweep_id = prev_sweep_id;
		}

		expected = compute_store_pattern(tid, iter_ptr, expected_sweep_id);

		dcbf((volatile unsigned int*)iter_ptr); //Flush before reading
		observed = *iter_ptr;

	        if (observed != expected) {
			nr_anamolies++;
			log_anamoly(tid, iter_ptr, expected, observed);
		}
	}

	end_verification_log(tid, nr_anamolies);
}

static void set_pthread_cpu(pthread_t th, int cpu)
{
	cpu_set_t run_cpu_mask;
	struct sched_param param;

	CPU_ZERO(&run_cpu_mask);
	CPU_SET(cpu, &run_cpu_mask);
	pthread_setaffinity_np(th, sizeof(cpu_set_t), &run_cpu_mask);

	param.sched_priority = 1;
	if (0 && sched_setscheduler(0, SCHED_FIFO, &param) == -1) {
		/* haven't reproduced with this setting, it kills random preemption which may be a factor */
		fprintf(stderr, "could not set SCHED_FIFO, run as root?\n");
	}
}

static void set_mycpu(int cpu)
{
	cpu_set_t run_cpu_mask;
	struct sched_param param;

	CPU_ZERO(&run_cpu_mask);
	CPU_SET(cpu, &run_cpu_mask);
	sched_setaffinity(0, sizeof(cpu_set_t), &run_cpu_mask);

	param.sched_priority = 1;
	if (0 && sched_setscheduler(0, SCHED_FIFO, &param) == -1) {
		fprintf(stderr, "could not set SCHED_FIFO, run as root?\n");
	}
}

static volatile int segv_wait;

static void segv_handler(int signo, siginfo_t *info, void *extra)
{
	while (segv_wait) {
		sched_yield();
	}

}

static void set_segv_handler(void)
{
	struct sigaction sa;

	sa.sa_flags = SA_SIGINFO;
	sa.sa_sigaction = segv_handler;

	if (sigaction(SIGSEGV, &sa, NULL) == -1) {
		perror("sigaction");
		exit(EXIT_FAILURE);
	}
}

int timeout = 0;
/*
 * This function is executed by every rim_thread.
 *
 * This function performs sweeps over the exclusive chunks of the
 * rim_threads executing the rim-sequence one word at a time.
 */
static void *rim_fn(void *arg)
{
	unsigned int tid = *((unsigned int *)arg);

	int size = RIM_CHUNK_SIZE;
	char *chunk_start = compute_chunk_start_addr(tid);

	unsigned int prev_sweep_id;
	unsigned int cur_sweep_id = 0;

	/* word access */
	unsigned int pattern = cur_sweep_id;
	unsigned int *pattern_ptr = &pattern;
	unsigned int *w_ptr, read_data;

	set_segv_handler();

	/*
	 * Let us initialize the chunk:
	 *
	 * Each word-aligned address addr in the chunk,
	 * is initialized to :
	 *    |-------------------------------------------------|
	 *    | tid   | word_offset(addr) |         0           |
	 *    |-------------------------------------------------|
	 */
	for (w_ptr = (unsigned int *)chunk_start;
	     (unsigned long)w_ptr < (unsigned long)(chunk_start) + size;
	     w_ptr++) {

		*pattern_ptr = compute_store_pattern(tid, w_ptr, cur_sweep_id);
		*w_ptr = *pattern_ptr;
	}

	while (!corruption_found && !timeout) {
		prev_sweep_id = cur_sweep_id;
		cur_sweep_id = cur_sweep_id + 1;

		for (w_ptr = (unsigned int *)chunk_start;
		     (unsigned long)w_ptr < (unsigned long)(chunk_start) + size;
		     w_ptr++)  {
			unsigned int old_pattern;

			/*
			 * Compute the pattern that we would have
			 * stored at this location in the previous
			 * sweep.
			 */
			old_pattern = compute_store_pattern(tid, w_ptr, prev_sweep_id);

			/*
			 * FLUSH:Ensure that we flush the contents of
			 *       the cache before loading
			 */
			dcbf((volatile unsigned int*)w_ptr); //Flush

			/* LOAD: Read the value */
			read_data = *w_ptr; //Load

			/*
			 * COMPARE: Is it the same as what we had stored
			 *          in the previous sweep ? It better be!
			 */
			if (read_data != old_pattern) {
				/* No it isn't! Tell everyone */
				corruption_found = 1;
			}

			/*
			 * Before performing a store, let us check if
			 * any rim_thread has found a corruption.
			 */
			if (corruption_found || timeout) {
				/*
				 * Yes. Someone (including us!) has found
				 * a corruption :(
				 *
				 * Let us verify that our chunk is
				 * correct.
				 */
				/* But first, let us allow the dust to settle down! */
				verify_chunk(tid, w_ptr, cur_sweep_id, prev_sweep_id);

				return 0;
			}

			/*
			 * Compute the new pattern that we are going
			 * to write to this location
			 */
			*pattern_ptr = compute_store_pattern(tid, w_ptr, cur_sweep_id);

			/*
			 * STORE: Now let us write this pattern into
			 *        the location
			 */
			*w_ptr = *pattern_ptr;
		}
	}

	return NULL;
}


static unsigned long start_cpu = 0;
static unsigned long nrthreads = 4;

static pthread_t mem_snapshot_thread;

static void *mem_snapshot_fn(void *arg)
{
	int page_size = getpagesize();
	size_t size = page_size;
	void *tmp = malloc(size);

	while (!corruption_found && !timeout) {
		/* Stop memory migration once corruption is found */
		segv_wait = 1;

		mprotect(map1, size, PROT_READ);

		/*
		 * Load from the working alias (map1). Loading from map2
		 * also fails.
		 */
		memcpy(tmp, map1, size);

		/*
		 * Stores must go via map2 which has write permissions, but
		 * the corrupted data tends to be seen in the snapshot buffer,
		 * so corruption does not appear to be introduced at the
		 * copy-back via map2 alias here.
		 */
		memcpy(map2, tmp, size);
		/*
		 * Before releasing other threads, must ensure the copy
		 * back to
		 */
		asm volatile("sync" ::: "memory");
		mprotect(map1, size, PROT_READ|PROT_WRITE);
		asm volatile("sync" ::: "memory");
		segv_wait = 0;

		usleep(1); /* This value makes a big difference */
	}

	return 0;
}

void alrm_sighandler(int sig)
{
	timeout = 1;
}

int main(int argc, char *argv[])
{
	int c;
	int page_size = getpagesize();
	time_t now;
	int i, dir_error;
	pthread_attr_t attr;
	key_t shm_key = (key_t) getpid();
	int shmid, run_time = 20 * 60;
	struct sigaction sa_alrm;

	snprintf(logdir, LOGDIR_NAME_SIZE,
		 "/tmp/logdir-%u", (unsigned int)getpid());
	while ((c = getopt(argc, argv, "r:hn:l:t:")) != -1) {
		switch(c) {
		case 'r':
			start_cpu = strtoul(optarg, NULL, 10);
			break;
		case 'h':
			printf("%s [-r <start_cpu>] [-n <nrthreads>] [-l <logdir>] [-t <timeout>]\n", argv[0]);
			exit(0);
			break;
		case 'n':
			nrthreads = strtoul(optarg, NULL, 10);
			break;
		case 'l':
			strncpy(logdir, optarg, LOGDIR_NAME_SIZE - 1);
			break;
		case 't':
			run_time = strtoul(optarg, NULL, 10);
			break;
		default:
			printf("invalid option\n");
			exit(0);
			break;
		}
	}

	if (nrthreads > MAX_THREADS)
		nrthreads = MAX_THREADS;

	shmid = shmget(shm_key, page_size, IPC_CREAT|0666);
	if (shmid < 0) {
		err_msg("Failed shmget\n");
	}

	map1 = shmat(shmid, NULL, 0);
	if (map1 == (void *) -1) {
		err_msg("Failed shmat");
	}

	map2 = shmat(shmid, NULL, 0);
	if (map2 == (void *) -1) {
		err_msg("Failed shmat");
	}

	dir_error = mkdir(logdir, 0755);

	if (dir_error) {
		err_msg("Failed mkdir");
	}

	printf("start_cpu list:%lu\n", start_cpu);
	printf("number of worker threads:%lu + 1 snapshot thread\n", nrthreads);
	printf("Allocated address:0x%016lx + secondary map:0x%016lx\n", (unsigned long)map1, (unsigned long)map2);
	printf("logdir at : %s\n", logdir);
	printf("Timeout: %d seconds\n", run_time);

	time(&now);
	printf("=================================\n");
	printf("     Starting Test\n");
	printf("     %s", ctime(&now));
	printf("=================================\n");

	for (i = 0; i < nrthreads; i++) {
		if (1 && !fork()) {
			prctl(PR_SET_PDEATHSIG, SIGKILL);
			set_mycpu(start_cpu + i);
			for (;;)
				sched_yield();
			exit(0);
		}
	}


	sa_alrm.sa_handler = &alrm_sighandler;
	sigemptyset(&sa_alrm.sa_mask);
	sa_alrm.sa_flags = 0;

	if (sigaction(SIGALRM, &sa_alrm, 0) == -1) {
		err_msg("Failed signal handler registration\n");
	}

	alarm(run_time);

	pthread_attr_init(&attr);
	for (i = 0; i < nrthreads; i++) {
		rim_thread_ids[i] = i;
		pthread_create(&rim_threads[i], &attr, rim_fn, &rim_thread_ids[i]);
		set_pthread_cpu(rim_threads[i], start_cpu + i);
	}

	pthread_create(&mem_snapshot_thread, &attr, mem_snapshot_fn, map1);
	set_pthread_cpu(mem_snapshot_thread, start_cpu + i);


	pthread_join(mem_snapshot_thread, NULL);
	for (i = 0; i < nrthreads; i++) {
		pthread_join(rim_threads[i], NULL);
	}

	if (!timeout) {
		time(&now);
		printf("=================================\n");
		printf("      Data Corruption Detected\n");
		printf("      %s", ctime(&now));
		printf("      See logfiles in %s\n", logdir);
		printf("=================================\n");
		return 1;
	}
	return 0;
}