Attachment 201852 Details for Bug 235611 – Test program

Test program

kcovtrace.c (text/plain), 2.31 KB, created by Michael Tuexen on 2019-02-08 20:49:11 UTC

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Creator: Michael Tuexen

Created: 2019-02-08 20:49:11 UTC

Size: 2.31 KB

patch

obsolete

>// Copyright 2017 syzkaller project authors. All rights reserved.
>// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
>
>// kcovtrace is like strace but show kernel coverage collected with KCOV.
>// It is very simplistic at this point and does not support multithreaded processes, etc.
>// It can be used to understand, for example, exact location where kernel bails out
>// with an error for a particular syscall.
>
>#include <fcntl.h>
>#include <stddef.h>
>#include <stdint.h>
>#include <stdio.h>
>#include <stdlib.h>
>#include <sys/ioctl.h>
>#include <sys/mman.h>
>#include <sys/stat.h>
>#include <sys/types.h>
>#include <sys/wait.h>
>#include <unistd.h>
>
>#if defined(__FreeBSD__)
>#include <sys/kcov.h>
>#define KCOV_PATH "/dev/kcov"
>#else
>#define KCOV_INIT_TRACE _IOR('c', 1, unsigned long)
>#define KCOV_ENABLE _IO('c', 100)
>#define KCOV_DISABLE _IO('c', 101)
>#define KCOV_ENTRY_SIZE sizeof(unsigned long)
>#define KCOV_PATH "/sys/kernel/debug/kcov"
>#define KCOV_TRACE_PC 0
>#endif
>#define COVER_SIZE (16 << 20)
>
>int main(int argc, char** argv, char** envp)
>{
>	int fd, pid, status;
>	unsigned long *cover, n, i;
>
>	if (argc == 1)
>		fprintf(stderr, "usage: kcovtrace program [args...]\n"), exit(1);
>	fd = open(KCOV_PATH, O_RDWR);
>	if (fd == -1)
>		perror("open"), exit(1);
>#if defined(__FreeBSD__)
>	if (ioctl(fd, KIOSETBUFSIZE, COVER_SIZE))
>#else
>	if (ioctl(fd, KCOV_INIT_TRACE, COVER_SIZE))
>#endif
>		perror("ioctl"), exit(1);
>	cover = (unsigned long*)mmap(NULL, COVER_SIZE * KCOV_ENTRY_SIZE,
>				     PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
>	if ((void*)cover == MAP_FAILED)
>		perror("mmap"), exit(1);
>	pid = fork();
>	if (pid < 0)
>		perror("fork"), exit(1);
>	if (pid == 0) {
>#if defined(__FreeBSD__)
>		if (ioctl(fd, KIOENABLE, KCOV_MODE_TRACE_PC))
>#else
>		if (ioctl(fd, KCOV_ENABLE, KCOV_TRACE_PC))
>#endif
>			perror("ioctl"), exit(1);
>		__atomic_store_n(&cover[0], 0, __ATOMIC_RELAXED);
>		execve(argv[1], argv + 1, envp);
>		perror("execve");
>		exit(1);
>	}
>#if defined(__FreeBSD__)
>	while (waitpid(-1, &status, 0) != pid) {
>#else
>	while (waitpid(-1, &status, __WALL) != pid) {
>#endif
>	}
>	n = __atomic_load_n(&cover[0], __ATOMIC_RELAXED);
>	for (i = 0; i < n; i++)
>		printf("0x%lx\n", cover[i + 1]);
>	if (munmap(cover, COVER_SIZE * KCOV_ENTRY_SIZE))
>		perror("munmap"), exit(1);
>	if (close(fd))
>		perror("close"), exit(1);
>	return 0;
>}

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Attachments on bug 235611: 201852