where does vdso live for a three threaded process

vdso_threads.c (text/x-c), 998 bytes, created by Anthony Basile on 2014-11-12 01:17:19 UTC

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <linux/limits.h>


static void print_vdso_addr(pid_t p, pid_t t)  {
	char buf[PATH_MAX];
	char *line;
	size_t s;
	FILE *f;

	sprintf(buf, "/proc/%ld/task/%ld/maps", (long)p, (long)t);

	if((f = fopen(buf, "r")) == NULL) {
		fprintf(stderr, "Failed to fopen %s\n", buf);
		exit(EXIT_FAILURE);
	}

	while(getline(&line, &s, f) != -1) {
		if(strstr(line, "vdso"))
			printf("%s", line);
	}

	fclose(f);
}

static void *read_vdso(void *arg) {
	pid_t tid, *pid;
	pid = arg;
	tid = syscall(SYS_gettid);
	print_vdso_addr(*pid, tid);
}

int main() {
	pid_t pid;
	pthread_t t1, t2;

	pid = getpid();
	print_vdso_addr(pid, pid);

	pthread_create(&t1, NULL, read_vdso, (void *)&pid);
	pthread_create(&t2, NULL, read_vdso, (void *)&pid);
	pthread_join(t2, NULL);
	pthread_join(t1, NULL);

	exit(EXIT_SUCCESS);
}