test_kcov.c

// gcc -o test_kcov test_kcov.c -static
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <unistd.h>

// KCOV IOCTL 定义
#define KCOV_INIT_TRACE  _IOR('c', 1, unsigned long)
#define KCOV_ENABLE      _IO('c', 100)
#define KCOV_DISABLE     _IO('c', 101)

int main() {
    const char *kcov_path = "/sys/kernel/debug/kcov";
    int kcov_fd;
    unsigned long *kcov_buffer;
    unsigned long kcov_size = 65536; // KCOV 缓冲区大小
    int fd;

    // 打开 kcov 文件
    kcov_fd = open(kcov_path, O_RDWR);
    if (kcov_fd < 0) {
        perror("open kcov");
        return 1;
    }

    // 初始化 KCOV 缓冲区
    if (ioctl(kcov_fd, KCOV_INIT_TRACE, kcov_size) < 0) {
        perror("ioctl KCOV_INIT_TRACE");
        close(kcov_fd);
        return 1;
    }

    // 将 KCOV 缓冲区映射到用户空间
    kcov_buffer = mmap(NULL, kcov_size * sizeof(unsigned long),
                       PROT_READ | PROT_WRITE, MAP_SHARED, kcov_fd, 0);
    if (kcov_buffer == MAP_FAILED) {
        perror("mmap");
        close(kcov_fd);
        return 1;
    }

    // 打开一个需要测试的文件或触发内核代码
    fd = open("/dev/null", O_RDWR);
    if (fd < 0) {
        perror("open /dev/null");
        munmap(kcov_buffer, kcov_size * sizeof(unsigned long));
        close(kcov_fd);
        return 1;
    }

    // 启用 KCOV
    if (ioctl(kcov_fd, KCOV_ENABLE, 0) < 0) {
        perror("ioctl KCOV_ENABLE");
        close(fd);
        munmap(kcov_buffer, kcov_size * sizeof(unsigned long));
        close(kcov_fd);
        return 1;
    }

    // 模拟执行一些操作
    write(fd, "test", 4);
    read(fd, NULL, 0);

    // 禁用 KCOV
    if (ioctl(kcov_fd, KCOV_DISABLE, 0) < 0) {
        perror("ioctl KCOV_DISABLE");
    }

    // 输出覆盖率数据
    unsigned long entries = kcov_buffer[0];
    printf("Coverage entries: %lu\n", entries);
    for (unsigned long i = 1; i <= entries; i++) {
        printf("  0x%lx\n", kcov_buffer[i]);
    }

    // 清理资源
    close(fd);
    munmap(kcov_buffer, kcov_size * sizeof(unsigned long));
    close(kcov_fd);

    return 0;
}