hyp_kcov_test/hyp_kcov.c

#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/types.h>
#include <sys/sysinfo.h>

#define KCOV_INIT_TRACE			_IOR('c', 1, unsigned long)
#define KCOV_INIT_HYP_TRACE		_IOR('c', 2, unsigned long)
#define KCOV_ENABLE			_IO('c', 100)
#define KCOV_DISABLE			_IO('c', 101)
#define COVER_SIZE			(4096)

#define KCOV_TRACE_PC  0
#define KCOV_TRACE_CMP 1

struct kcov_meta_buffer {
	unsigned long num_entries;
	unsigned long entry[];
};

int main(int argc, char **argv)
{
    int fd;
    unsigned long n, i;
    unsigned int j, size;
    struct kcov_meta_buffer *cover;
    void *ptr;

    /* A single fd descriptor allows coverage collection on a single
     * thread.
     */
    fd = open("/sys/kernel/debug/kcov", O_RDWR);
    if (fd == -1)
	perror("open"), exit(1);

    /* Setup trace mode and trace size. */
    if (ioctl(fd, KCOV_INIT_HYP_TRACE, COVER_SIZE))
	perror("ioctl"), exit(1);

    /* Mmap buffer shared between kernel- and user-space. */
    ptr = mmap(NULL, COVER_SIZE * sizeof(unsigned long),
	       PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    if ((void*)ptr == MAP_FAILED)
	perror("mmap"), exit(1);

    n = get_nprocs();
    size = COVER_SIZE / n;
    printf("Number CPUS: %d\n", n);

    while (1) {
	    for (i = 0; i < n; i++) {
		cover = (struct kcov_meta_buffer *)(ptr + size);
		printf("CPU %d got 0x%lx entries\n", i, cover->num_entries);

		for (j = 0; j < cover->num_entries; j++) {
			printf("0x%lx\n", cover->entry[j]);
		}

		/* Reset coverage from the tail of the ioctl() call. */
		__atomic_store_n(&cover->num_entries, 0, __ATOMIC_RELAXED);
	    }
    }

    /* Disable coverage collection for the current thread. After this call
     * coverage can be enabled for a different thread.
     */
    if (ioctl(fd, KCOV_DISABLE, 0))
	perror("ioctl"), exit(1);

    /* Free resources. */
    if (munmap(cover, COVER_SIZE * sizeof(unsigned long)))
	perror("munmap"), exit(1);

    if (close(fd))
	perror("close"), exit(1);
    return 0;
}