1 // SPDX-License-Identifier: GPL-2.0
2 
3 /*
4  * Copyright 2019, Nick Piggin, Gautham R. Shenoy, Aneesh Kumar K.V, IBM Corp.
5  */
6 
7 /*
8  *
9  * Test tlbie/mtpidr race. We have 4 threads doing flush/load/compare/store
10  * sequence in a loop. The same threads also rung a context switch task
11  * that does sched_yield() in loop.
12  *
13  * The snapshot thread mark the mmap area PROT_READ in between, make a copy
14  * and copy it back to the original area. This helps us to detect if any
15  * store continued to happen after we marked the memory PROT_READ.
16  */
17 
18 #define _GNU_SOURCE
19 #include <stdio.h>
20 #include <sys/mman.h>
21 #include <sys/types.h>
22 #include <sys/wait.h>
23 #include <sys/ipc.h>
24 #include <sys/shm.h>
25 #include <sys/stat.h>
26 #include <sys/time.h>
27 #include <linux/futex.h>
28 #include <unistd.h>
29 #include <asm/unistd.h>
30 #include <string.h>
31 #include <stdlib.h>
32 #include <fcntl.h>
33 #include <sched.h>
34 #include <time.h>
35 #include <stdarg.h>
36 #include <pthread.h>
37 #include <signal.h>
38 #include <sys/prctl.h>
39 
dcbf(volatile unsigned int * addr)40 static inline void dcbf(volatile unsigned int *addr)
41 {
42 	__asm__ __volatile__ ("dcbf %y0; sync" : : "Z"(*(unsigned char *)addr) : "memory");
43 }
44 
err_msg(char * msg)45 static void err_msg(char *msg)
46 {
47 
48 	time_t now;
49 	time(&now);
50 	printf("=================================\n");
51 	printf("    Error: %s\n", msg);
52 	printf("    %s", ctime(&now));
53 	printf("=================================\n");
54 	exit(1);
55 }
56 
57 static char *map1;
58 static char *map2;
59 static pid_t rim_process_pid;
60 
61 /*
62  * A "rim-sequence" is defined to be the sequence of the following
63  * operations performed on a memory word:
64  *	1) FLUSH the contents of that word.
65  *	2) LOAD the contents of that word.
66  *	3) COMPARE the contents of that word with the content that was
67  *	           previously stored at that word
68  *	4) STORE new content into that word.
69  *
70  * The threads in this test that perform the rim-sequence are termed
71  * as rim_threads.
72  */
73 
74 /*
75  * A "corruption" is defined to be the failed COMPARE operation in a
76  * rim-sequence.
77  *
78  * A rim_thread that detects a corruption informs about it to all the
79  * other rim_threads, and the mem_snapshot thread.
80  */
81 static volatile unsigned int corruption_found;
82 
83 /*
84  * This defines the maximum number of rim_threads in this test.
85  *
86  * The THREAD_ID_BITS denote the number of bits required
87  * to represent the thread_ids [0..MAX_THREADS - 1].
88  * We are being a bit paranoid here and set it to 8 bits,
89  * though 6 bits suffice.
90  *
91  */
92 #define MAX_THREADS 		64
93 #define THREAD_ID_BITS		8
94 #define THREAD_ID_MASK		((1 << THREAD_ID_BITS) - 1)
95 static unsigned int rim_thread_ids[MAX_THREADS];
96 static pthread_t rim_threads[MAX_THREADS];
97 
98 
99 /*
100  * Each rim_thread works on an exclusive "chunk" of size
101  * RIM_CHUNK_SIZE.
102  *
103  * The ith rim_thread works on the ith chunk.
104  *
105  * The ith chunk begins at
106  * map1 + (i * RIM_CHUNK_SIZE)
107  */
108 #define RIM_CHUNK_SIZE  	1024
109 #define BITS_PER_BYTE 		8
110 #define WORD_SIZE     		(sizeof(unsigned int))
111 #define WORD_BITS		(WORD_SIZE * BITS_PER_BYTE)
112 #define WORDS_PER_CHUNK		(RIM_CHUNK_SIZE/WORD_SIZE)
113 
compute_chunk_start_addr(unsigned int thread_id)114 static inline char *compute_chunk_start_addr(unsigned int thread_id)
115 {
116 	char *chunk_start;
117 
118 	chunk_start = (char *)((unsigned long)map1 +
119 			       (thread_id * RIM_CHUNK_SIZE));
120 
121 	return chunk_start;
122 }
123 
124 /*
125  * The "word-offset" of a word-aligned address inside a chunk, is
126  * defined to be the number of words that precede the address in that
127  * chunk.
128  *
129  * WORD_OFFSET_BITS denote the number of bits required to represent
130  * the word-offsets of all the word-aligned addresses of a chunk.
131  */
132 #define WORD_OFFSET_BITS	(__builtin_ctz(WORDS_PER_CHUNK))
133 #define WORD_OFFSET_MASK	((1 << WORD_OFFSET_BITS) - 1)
134 
compute_word_offset(char * start,unsigned int * addr)135 static inline unsigned int compute_word_offset(char *start, unsigned int *addr)
136 {
137 	unsigned int delta_bytes, ret;
138 	delta_bytes = (unsigned long)addr - (unsigned long)start;
139 
140 	ret = delta_bytes/WORD_SIZE;
141 
142 	return ret;
143 }
144 
145 /*
146  * A "sweep" is defined to be the sequential execution of the
147  * rim-sequence by a rim_thread on its chunk one word at a time,
148  * starting from the first word of its chunk and ending with the last
149  * word of its chunk.
150  *
151  * Each sweep of a rim_thread is uniquely identified by a sweep_id.
152  * SWEEP_ID_BITS denote the number of bits required to represent
153  * the sweep_ids of rim_threads.
154  *
155  * As to why SWEEP_ID_BITS are computed as a function of THREAD_ID_BITS,
156  * WORD_OFFSET_BITS, and WORD_BITS, see the "store-pattern" below.
157  */
158 #define SWEEP_ID_BITS		(WORD_BITS - (THREAD_ID_BITS + WORD_OFFSET_BITS))
159 #define SWEEP_ID_MASK		((1 << SWEEP_ID_BITS) - 1)
160 
161 /*
162  * A "store-pattern" is the word-pattern that is stored into a word
163  * location in the 4)STORE step of the rim-sequence.
164  *
165  * In the store-pattern, we shall encode:
166  *
167  *      - The thread-id of the rim_thread performing the store
168  *        (The most significant THREAD_ID_BITS)
169  *
170  *      - The word-offset of the address into which the store is being
171  *        performed (The next WORD_OFFSET_BITS)
172  *
173  *      - The sweep_id of the current sweep in which the store is
174  *        being performed. (The lower SWEEP_ID_BITS)
175  *
176  * Store Pattern: 32 bits
177  * |------------------|--------------------|---------------------------------|
178  * |    Thread id     |  Word offset       |         sweep_id                |
179  * |------------------|--------------------|---------------------------------|
180  *    THREAD_ID_BITS     WORD_OFFSET_BITS          SWEEP_ID_BITS
181  *
182  * In the store pattern, the (Thread-id + Word-offset) uniquely identify the
183  * address to which the store is being performed i.e,
184  *    address == map1 +
185  *              (Thread-id * RIM_CHUNK_SIZE) + (Word-offset * WORD_SIZE)
186  *
187  * And the sweep_id in the store pattern identifies the time when the
188  * store was performed by the rim_thread.
189  *
190  * We shall use this property in the 3)COMPARE step of the
191  * rim-sequence.
192  */
193 #define SWEEP_ID_SHIFT	0
194 #define WORD_OFFSET_SHIFT	(SWEEP_ID_BITS)
195 #define THREAD_ID_SHIFT		(WORD_OFFSET_BITS + SWEEP_ID_BITS)
196 
197 /*
198  * Compute the store pattern for a given thread with id @tid, at
199  * location @addr in the sweep identified by @sweep_id
200  */
compute_store_pattern(unsigned int tid,unsigned int * addr,unsigned int sweep_id)201 static inline unsigned int compute_store_pattern(unsigned int tid,
202 						 unsigned int *addr,
203 						 unsigned int sweep_id)
204 {
205 	unsigned int ret = 0;
206 	char *start = compute_chunk_start_addr(tid);
207 	unsigned int word_offset = compute_word_offset(start, addr);
208 
209 	ret += (tid & THREAD_ID_MASK) << THREAD_ID_SHIFT;
210 	ret += (word_offset & WORD_OFFSET_MASK) << WORD_OFFSET_SHIFT;
211 	ret += (sweep_id & SWEEP_ID_MASK) << SWEEP_ID_SHIFT;
212 	return ret;
213 }
214 
215 /* Extract the thread-id from the given store-pattern */
extract_tid(unsigned int pattern)216 static inline unsigned int extract_tid(unsigned int pattern)
217 {
218 	unsigned int ret;
219 
220 	ret = (pattern >> THREAD_ID_SHIFT) & THREAD_ID_MASK;
221 	return ret;
222 }
223 
224 /* Extract the word-offset from the given store-pattern */
extract_word_offset(unsigned int pattern)225 static inline unsigned int extract_word_offset(unsigned int pattern)
226 {
227 	unsigned int ret;
228 
229 	ret = (pattern >> WORD_OFFSET_SHIFT) & WORD_OFFSET_MASK;
230 
231 	return ret;
232 }
233 
234 /* Extract the sweep-id from the given store-pattern */
extract_sweep_id(unsigned int pattern)235 static inline unsigned int extract_sweep_id(unsigned int pattern)
236 
237 {
238 	unsigned int ret;
239 
240 	ret = (pattern >> SWEEP_ID_SHIFT) & SWEEP_ID_MASK;
241 
242 	return ret;
243 }
244 
245 /************************************************************
246  *                                                          *
247  *          Logging the output of the verification          *
248  *                                                          *
249  ************************************************************/
250 #define LOGDIR_NAME_SIZE 100
251 static char logdir[LOGDIR_NAME_SIZE];
252 
253 static FILE *fp[MAX_THREADS];
254 static const char logfilename[] ="Thread-%02d-Chunk";
255 
start_verification_log(unsigned int tid,unsigned int * addr,unsigned int cur_sweep_id,unsigned int prev_sweep_id)256 static inline void start_verification_log(unsigned int tid,
257 					  unsigned int *addr,
258 					  unsigned int cur_sweep_id,
259 					  unsigned int prev_sweep_id)
260 {
261 	FILE *f;
262 	char logfile[30];
263 	char path[LOGDIR_NAME_SIZE + 30];
264 	char separator[2] = "/";
265 	char *chunk_start = compute_chunk_start_addr(tid);
266 	unsigned int size = RIM_CHUNK_SIZE;
267 
268 	sprintf(logfile, logfilename, tid);
269 	strcpy(path, logdir);
270 	strcat(path, separator);
271 	strcat(path, logfile);
272 	f = fopen(path, "w");
273 
274 	if (!f) {
275 		err_msg("Unable to create logfile\n");
276 	}
277 
278 	fp[tid] = f;
279 
280 	fprintf(f, "----------------------------------------------------------\n");
281 	fprintf(f, "PID                = %d\n", rim_process_pid);
282 	fprintf(f, "Thread id          = %02d\n", tid);
283 	fprintf(f, "Chunk Start Addr   = 0x%016lx\n", (unsigned long)chunk_start);
284 	fprintf(f, "Chunk Size         = %d\n", size);
285 	fprintf(f, "Next Store Addr    = 0x%016lx\n", (unsigned long)addr);
286 	fprintf(f, "Current sweep-id   = 0x%08x\n", cur_sweep_id);
287 	fprintf(f, "Previous sweep-id  = 0x%08x\n", prev_sweep_id);
288 	fprintf(f, "----------------------------------------------------------\n");
289 }
290 
log_anamoly(unsigned int tid,unsigned int * addr,unsigned int expected,unsigned int observed)291 static inline void log_anamoly(unsigned int tid, unsigned int *addr,
292 			       unsigned int expected, unsigned int observed)
293 {
294 	FILE *f = fp[tid];
295 
296 	fprintf(f, "Thread %02d: Addr 0x%lx: Expected 0x%x, Observed 0x%x\n",
297 	        tid, (unsigned long)addr, expected, observed);
298 	fprintf(f, "Thread %02d: Expected Thread id   = %02d\n", tid, extract_tid(expected));
299 	fprintf(f, "Thread %02d: Observed Thread id   = %02d\n", tid, extract_tid(observed));
300 	fprintf(f, "Thread %02d: Expected Word offset = %03d\n", tid, extract_word_offset(expected));
301 	fprintf(f, "Thread %02d: Observed Word offset = %03d\n", tid, extract_word_offset(observed));
302 	fprintf(f, "Thread %02d: Expected sweep-id    = 0x%x\n", tid, extract_sweep_id(expected));
303 	fprintf(f, "Thread %02d: Observed sweep-id    = 0x%x\n", tid, extract_sweep_id(observed));
304 	fprintf(f, "----------------------------------------------------------\n");
305 }
306 
end_verification_log(unsigned int tid,unsigned nr_anamolies)307 static inline void end_verification_log(unsigned int tid, unsigned nr_anamolies)
308 {
309 	FILE *f = fp[tid];
310 	char logfile[30];
311 	char path[LOGDIR_NAME_SIZE + 30];
312 	char separator[] = "/";
313 
314 	fclose(f);
315 
316 	if (nr_anamolies == 0) {
317 		remove(path);
318 		return;
319 	}
320 
321 	sprintf(logfile, logfilename, tid);
322 	strcpy(path, logdir);
323 	strcat(path, separator);
324 	strcat(path, logfile);
325 
326 	printf("Thread %02d chunk has %d corrupted words. For details check %s\n",
327 		tid, nr_anamolies, path);
328 }
329 
330 /*
331  * When a COMPARE step of a rim-sequence fails, the rim_thread informs
332  * everyone else via the shared_memory pointed to by
333  * corruption_found variable. On seeing this, every thread verifies the
334  * content of its chunk as follows.
335  *
336  * Suppose a thread identified with @tid was about to store (but not
337  * yet stored) to @next_store_addr in its current sweep identified
338  * @cur_sweep_id. Let @prev_sweep_id indicate the previous sweep_id.
339  *
340  * This implies that for all the addresses @addr < @next_store_addr,
341  * Thread @tid has already performed a store as part of its current
342  * sweep. Hence we expect the content of such @addr to be:
343  *    |-------------------------------------------------|
344  *    | tid   | word_offset(addr) |    cur_sweep_id     |
345  *    |-------------------------------------------------|
346  *
347  * Since Thread @tid is yet to perform stores on address
348  * @next_store_addr and above, we expect the content of such an
349  * address @addr to be:
350  *    |-------------------------------------------------|
351  *    | tid   | word_offset(addr) |    prev_sweep_id    |
352  *    |-------------------------------------------------|
353  *
354  * The verifier function @verify_chunk does this verification and logs
355  * any anamolies that it finds.
356  */
verify_chunk(unsigned int tid,unsigned int * next_store_addr,unsigned int cur_sweep_id,unsigned int prev_sweep_id)357 static void verify_chunk(unsigned int tid, unsigned int *next_store_addr,
358 		  unsigned int cur_sweep_id,
359 		  unsigned int prev_sweep_id)
360 {
361 	unsigned int *iter_ptr;
362 	unsigned int size = RIM_CHUNK_SIZE;
363 	unsigned int expected;
364 	unsigned int observed;
365 	char *chunk_start = compute_chunk_start_addr(tid);
366 
367 	int nr_anamolies = 0;
368 
369 	start_verification_log(tid, next_store_addr,
370 			       cur_sweep_id, prev_sweep_id);
371 
372 	for (iter_ptr = (unsigned int *)chunk_start;
373 	     (unsigned long)iter_ptr < (unsigned long)chunk_start + size;
374 	     iter_ptr++) {
375 		unsigned int expected_sweep_id;
376 
377 		if (iter_ptr < next_store_addr) {
378 			expected_sweep_id = cur_sweep_id;
379 		} else {
380 			expected_sweep_id = prev_sweep_id;
381 		}
382 
383 		expected = compute_store_pattern(tid, iter_ptr, expected_sweep_id);
384 
385 		dcbf((volatile unsigned int*)iter_ptr); //Flush before reading
386 		observed = *iter_ptr;
387 
388 	        if (observed != expected) {
389 			nr_anamolies++;
390 			log_anamoly(tid, iter_ptr, expected, observed);
391 		}
392 	}
393 
394 	end_verification_log(tid, nr_anamolies);
395 }
396 
set_pthread_cpu(pthread_t th,int cpu)397 static void set_pthread_cpu(pthread_t th, int cpu)
398 {
399 	cpu_set_t run_cpu_mask;
400 	struct sched_param param;
401 
402 	CPU_ZERO(&run_cpu_mask);
403 	CPU_SET(cpu, &run_cpu_mask);
404 	pthread_setaffinity_np(th, sizeof(cpu_set_t), &run_cpu_mask);
405 
406 	param.sched_priority = 1;
407 	if (0 && sched_setscheduler(0, SCHED_FIFO, &param) == -1) {
408 		/* haven't reproduced with this setting, it kills random preemption which may be a factor */
409 		fprintf(stderr, "could not set SCHED_FIFO, run as root?\n");
410 	}
411 }
412 
set_mycpu(int cpu)413 static void set_mycpu(int cpu)
414 {
415 	cpu_set_t run_cpu_mask;
416 	struct sched_param param;
417 
418 	CPU_ZERO(&run_cpu_mask);
419 	CPU_SET(cpu, &run_cpu_mask);
420 	sched_setaffinity(0, sizeof(cpu_set_t), &run_cpu_mask);
421 
422 	param.sched_priority = 1;
423 	if (0 && sched_setscheduler(0, SCHED_FIFO, &param) == -1) {
424 		fprintf(stderr, "could not set SCHED_FIFO, run as root?\n");
425 	}
426 }
427 
428 static volatile int segv_wait;
429 
segv_handler(int signo,siginfo_t * info,void * extra)430 static void segv_handler(int signo, siginfo_t *info, void *extra)
431 {
432 	while (segv_wait) {
433 		sched_yield();
434 	}
435 
436 }
437 
set_segv_handler(void)438 static void set_segv_handler(void)
439 {
440 	struct sigaction sa;
441 
442 	sa.sa_flags = SA_SIGINFO;
443 	sa.sa_sigaction = segv_handler;
444 
445 	if (sigaction(SIGSEGV, &sa, NULL) == -1) {
446 		perror("sigaction");
447 		exit(EXIT_FAILURE);
448 	}
449 }
450 
451 int timeout = 0;
452 /*
453  * This function is executed by every rim_thread.
454  *
455  * This function performs sweeps over the exclusive chunks of the
456  * rim_threads executing the rim-sequence one word at a time.
457  */
rim_fn(void * arg)458 static void *rim_fn(void *arg)
459 {
460 	unsigned int tid = *((unsigned int *)arg);
461 
462 	int size = RIM_CHUNK_SIZE;
463 	char *chunk_start = compute_chunk_start_addr(tid);
464 
465 	unsigned int prev_sweep_id;
466 	unsigned int cur_sweep_id = 0;
467 
468 	/* word access */
469 	unsigned int pattern = cur_sweep_id;
470 	unsigned int *pattern_ptr = &pattern;
471 	unsigned int *w_ptr, read_data;
472 
473 	set_segv_handler();
474 
475 	/*
476 	 * Let us initialize the chunk:
477 	 *
478 	 * Each word-aligned address addr in the chunk,
479 	 * is initialized to :
480 	 *    |-------------------------------------------------|
481 	 *    | tid   | word_offset(addr) |         0           |
482 	 *    |-------------------------------------------------|
483 	 */
484 	for (w_ptr = (unsigned int *)chunk_start;
485 	     (unsigned long)w_ptr < (unsigned long)(chunk_start) + size;
486 	     w_ptr++) {
487 
488 		*pattern_ptr = compute_store_pattern(tid, w_ptr, cur_sweep_id);
489 		*w_ptr = *pattern_ptr;
490 	}
491 
492 	while (!corruption_found && !timeout) {
493 		prev_sweep_id = cur_sweep_id;
494 		cur_sweep_id = cur_sweep_id + 1;
495 
496 		for (w_ptr = (unsigned int *)chunk_start;
497 		     (unsigned long)w_ptr < (unsigned long)(chunk_start) + size;
498 		     w_ptr++)  {
499 			unsigned int old_pattern;
500 
501 			/*
502 			 * Compute the pattern that we would have
503 			 * stored at this location in the previous
504 			 * sweep.
505 			 */
506 			old_pattern = compute_store_pattern(tid, w_ptr, prev_sweep_id);
507 
508 			/*
509 			 * FLUSH:Ensure that we flush the contents of
510 			 *       the cache before loading
511 			 */
512 			dcbf((volatile unsigned int*)w_ptr); //Flush
513 
514 			/* LOAD: Read the value */
515 			read_data = *w_ptr; //Load
516 
517 			/*
518 			 * COMPARE: Is it the same as what we had stored
519 			 *          in the previous sweep ? It better be!
520 			 */
521 			if (read_data != old_pattern) {
522 				/* No it isn't! Tell everyone */
523 				corruption_found = 1;
524 			}
525 
526 			/*
527 			 * Before performing a store, let us check if
528 			 * any rim_thread has found a corruption.
529 			 */
530 			if (corruption_found || timeout) {
531 				/*
532 				 * Yes. Someone (including us!) has found
533 				 * a corruption :(
534 				 *
535 				 * Let us verify that our chunk is
536 				 * correct.
537 				 */
538 				/* But first, let us allow the dust to settle down! */
539 				verify_chunk(tid, w_ptr, cur_sweep_id, prev_sweep_id);
540 
541 				return 0;
542 			}
543 
544 			/*
545 			 * Compute the new pattern that we are going
546 			 * to write to this location
547 			 */
548 			*pattern_ptr = compute_store_pattern(tid, w_ptr, cur_sweep_id);
549 
550 			/*
551 			 * STORE: Now let us write this pattern into
552 			 *        the location
553 			 */
554 			*w_ptr = *pattern_ptr;
555 		}
556 	}
557 
558 	return NULL;
559 }
560 
561 
562 static unsigned long start_cpu = 0;
563 static unsigned long nrthreads = 4;
564 
565 static pthread_t mem_snapshot_thread;
566 
mem_snapshot_fn(void * arg)567 static void *mem_snapshot_fn(void *arg)
568 {
569 	int page_size = getpagesize();
570 	size_t size = page_size;
571 	void *tmp = malloc(size);
572 
573 	while (!corruption_found && !timeout) {
574 		/* Stop memory migration once corruption is found */
575 		segv_wait = 1;
576 
577 		mprotect(map1, size, PROT_READ);
578 
579 		/*
580 		 * Load from the working alias (map1). Loading from map2
581 		 * also fails.
582 		 */
583 		memcpy(tmp, map1, size);
584 
585 		/*
586 		 * Stores must go via map2 which has write permissions, but
587 		 * the corrupted data tends to be seen in the snapshot buffer,
588 		 * so corruption does not appear to be introduced at the
589 		 * copy-back via map2 alias here.
590 		 */
591 		memcpy(map2, tmp, size);
592 		/*
593 		 * Before releasing other threads, must ensure the copy
594 		 * back to
595 		 */
596 		asm volatile("sync" ::: "memory");
597 		mprotect(map1, size, PROT_READ|PROT_WRITE);
598 		asm volatile("sync" ::: "memory");
599 		segv_wait = 0;
600 
601 		usleep(1); /* This value makes a big difference */
602 	}
603 
604 	return 0;
605 }
606 
alrm_sighandler(int sig)607 void alrm_sighandler(int sig)
608 {
609 	timeout = 1;
610 }
611 
main(int argc,char * argv[])612 int main(int argc, char *argv[])
613 {
614 	int c;
615 	int page_size = getpagesize();
616 	time_t now;
617 	int i, dir_error;
618 	pthread_attr_t attr;
619 	key_t shm_key = (key_t) getpid();
620 	int shmid, run_time = 20 * 60;
621 	struct sigaction sa_alrm;
622 
623 	snprintf(logdir, LOGDIR_NAME_SIZE,
624 		 "/tmp/logdir-%u", (unsigned int)getpid());
625 	while ((c = getopt(argc, argv, "r:hn:l:t:")) != -1) {
626 		switch(c) {
627 		case 'r':
628 			start_cpu = strtoul(optarg, NULL, 10);
629 			break;
630 		case 'h':
631 			printf("%s [-r <start_cpu>] [-n <nrthreads>] [-l <logdir>] [-t <timeout>]\n", argv[0]);
632 			exit(0);
633 			break;
634 		case 'n':
635 			nrthreads = strtoul(optarg, NULL, 10);
636 			break;
637 		case 'l':
638 			strncpy(logdir, optarg, LOGDIR_NAME_SIZE - 1);
639 			break;
640 		case 't':
641 			run_time = strtoul(optarg, NULL, 10);
642 			break;
643 		default:
644 			printf("invalid option\n");
645 			exit(0);
646 			break;
647 		}
648 	}
649 
650 	if (nrthreads > MAX_THREADS)
651 		nrthreads = MAX_THREADS;
652 
653 	shmid = shmget(shm_key, page_size, IPC_CREAT|0666);
654 	if (shmid < 0) {
655 		err_msg("Failed shmget\n");
656 	}
657 
658 	map1 = shmat(shmid, NULL, 0);
659 	if (map1 == (void *) -1) {
660 		err_msg("Failed shmat");
661 	}
662 
663 	map2 = shmat(shmid, NULL, 0);
664 	if (map2 == (void *) -1) {
665 		err_msg("Failed shmat");
666 	}
667 
668 	dir_error = mkdir(logdir, 0755);
669 
670 	if (dir_error) {
671 		err_msg("Failed mkdir");
672 	}
673 
674 	printf("start_cpu list:%lu\n", start_cpu);
675 	printf("number of worker threads:%lu + 1 snapshot thread\n", nrthreads);
676 	printf("Allocated address:0x%016lx + secondary map:0x%016lx\n", (unsigned long)map1, (unsigned long)map2);
677 	printf("logdir at : %s\n", logdir);
678 	printf("Timeout: %d seconds\n", run_time);
679 
680 	time(&now);
681 	printf("=================================\n");
682 	printf("     Starting Test\n");
683 	printf("     %s", ctime(&now));
684 	printf("=================================\n");
685 
686 	for (i = 0; i < nrthreads; i++) {
687 		if (1 && !fork()) {
688 			prctl(PR_SET_PDEATHSIG, SIGKILL);
689 			set_mycpu(start_cpu + i);
690 			for (;;)
691 				sched_yield();
692 			exit(0);
693 		}
694 	}
695 
696 
697 	sa_alrm.sa_handler = &alrm_sighandler;
698 	sigemptyset(&sa_alrm.sa_mask);
699 	sa_alrm.sa_flags = 0;
700 
701 	if (sigaction(SIGALRM, &sa_alrm, 0) == -1) {
702 		err_msg("Failed signal handler registration\n");
703 	}
704 
705 	alarm(run_time);
706 
707 	pthread_attr_init(&attr);
708 	for (i = 0; i < nrthreads; i++) {
709 		rim_thread_ids[i] = i;
710 		pthread_create(&rim_threads[i], &attr, rim_fn, &rim_thread_ids[i]);
711 		set_pthread_cpu(rim_threads[i], start_cpu + i);
712 	}
713 
714 	pthread_create(&mem_snapshot_thread, &attr, mem_snapshot_fn, map1);
715 	set_pthread_cpu(mem_snapshot_thread, start_cpu + i);
716 
717 
718 	pthread_join(mem_snapshot_thread, NULL);
719 	for (i = 0; i < nrthreads; i++) {
720 		pthread_join(rim_threads[i], NULL);
721 	}
722 
723 	if (!timeout) {
724 		time(&now);
725 		printf("=================================\n");
726 		printf("      Data Corruption Detected\n");
727 		printf("      %s", ctime(&now));
728 		printf("      See logfiles in %s\n", logdir);
729 		printf("=================================\n");
730 		return 1;
731 	}
732 	return 0;
733 }
734