gistfile1.txt

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <pthread.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <stddef.h>

#define SIZE (128*1024)

int fd;
void *cov;
int cover[5];
uint32_t pcs[5][SIZE];
uint32_t tmppcs[5][SIZE];

void *thr(void *p)
{
	int n = write(fd, "enable", strlen("enable"));
	if (n != strlen("enable"))
		exit(printf("enable write failed (%d)\n", errno));
	int tmp[5] = {};
	int fds[2];
	*(volatile uint32_t*)cov = 0;
	pipe(fds);
	tmp[0] = *(volatile uint32_t*)cov;
	memcpy(tmppcs[0], &((uint32_t*)cov)[1], tmp[0] * sizeof(uint32_t));
	*(volatile uint32_t*)cov = 0;
	write(fds[1], &n, 1);
	tmp[1] = *(volatile uint32_t*)cov;
	memcpy(tmppcs[1], &((uint32_t*)cov)[1], tmp[1] * sizeof(uint32_t));
	*(volatile uint32_t*)cov = 0;
	read(fds[0], &n, 1);
	tmp[2] = *(volatile uint32_t*)cov;
	memcpy(tmppcs[2], &((uint32_t*)cov)[1], tmp[2] * sizeof(uint32_t));
	*(volatile uint32_t*)cov = 0;
	close(fds[0]);
	tmp[3] = *(volatile uint32_t*)cov;
	memcpy(tmppcs[3], &((uint32_t*)cov)[1], tmp[3] * sizeof(uint32_t));
	*(volatile uint32_t*)cov = 0;
	close(fds[1]);
	tmp[4] = *(volatile uint32_t*)cov;
	memcpy(tmppcs[4], &((uint32_t*)cov)[1], tmp[4] * sizeof(uint32_t));
	*(volatile uint32_t*)cov = 0;
	printf("cover: %d/%d/%d/%d/%d\n", tmp[0], tmp[1], tmp[2], tmp[3], tmp[4]);
	int i;
	for (i = 0; i < 5; i++) {
		if (tmp[i] == 0)
			exit(printf("u no cover?\n"));
		if (cover[i] == 0) {
			cover[i] = tmp[i];
			memcpy(pcs[i], tmppcs[i], tmp[i] * sizeof(uint32_t));
		}
		if (cover[i] != tmp[i] || memcmp(pcs[i], tmppcs[i], tmp[i] * sizeof(uint32_t))) {
			int start, end, x;
			for (start = 0; start < tmp[i] && start < cover[i] && pcs[i][start] == tmppcs[i][start]; start++);
			for (end = 0; end < tmp[i] && end < cover[i] && pcs[i][cover[i] - end - 1] == tmppcs[i][tmp[i] - end - 1]; end++);
			printf("diff %d: %d/%d %d/%d\n", i, cover[i], tmp[i], start, end);
			printf("old:");
			for (x = start; x < cover[i] - end; x++)
				printf(" 0x%lx", pcs[i][x] + 0xffffffff00000000ul);
			printf("\n\n");
			printf("new:");
			for (x = start; x < tmp[i] - end; x++)
				printf(" 0x%lx", tmppcs[i][x] + 0xffffffff00000000ul);
			printf("\n\n");
		}
	}
	return 0;
}

int main()
{
	fd = open("/sys/kernel/debug/kcov", O_RDWR);
	if (fd == -1)
		exit(printf("open failed (%d)\n", errno));
	char cmd[128];
	sprintf(cmd, "trace=%d", SIZE);
	int n = write(fd, cmd, strlen(cmd));
	if (n != strlen(cmd))
		exit(printf("write failed (%d)\n", errno));
	cov = mmap(NULL, SIZE * sizeof(uint32_t), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	if (cov == MAP_FAILED)
		exit(printf("mmap failed (%d)\n", errno));
	int i;
	for (i = 0; i < 5; i++) {
		pthread_t th;
		pthread_create(&th, 0, thr, 0);
		pthread_join(th, 0);
		usleep(10000);
	}
	return 0;
}