svn commit: r342962 - in head: sys/amd64/conf sys/arm64/conf sys/conf sys/kern sys/sys tests/sys/kern

[Cy Schubert]

In message <201901121121.x0CBLSiv058912 at repo.freebsd.org>, Andrew 
Turner writes
:
> Author: andrew
> Date: Sat Jan 12 11:21:28 2019
> New Revision: 342962
> URL: https://svnweb.freebsd.org/changeset/base/342962
>
> Log:
>   Add support for the Clang Coverage Sanitizer in the kernel (KCOV).
>   
>   When building with KCOV enabled the compiler will insert function calls
>   to probes allowing us to trace the execution of the kernel from userspace.
>   These probes are on function entry (trace-pc) and on comparison operations
>   (trace-cmp).
>   
>   Userspace can enable the use of these probes on a single kernel thread with
>   an ioctl interface. It can allocate space for the probe with KIOSETBUFSIZE,
>   then mmap the allocated buffer and enable tracing with KIOENABLE, with the
>   trace mode being passed in as the int argument. When complete KIODISABLE
>   is used to disable tracing.
>   
>   The first item in the buffer is the number of trace event that have
>   happened. Userspace can write 0 to this to reset the tracing, and is
>   expected to do so on first use.
>   
>   The format of the buffer depends on the trace mode. When in PC tracing just
>   the return address of the probe is stored. Under comparison tracing the
>   comparison type, the two arguments, and the return address are traced. The
>   former method uses on entry per trace event, while the later uses 4. As
>   such they are incompatible so only a single mode may be enabled.
>   
>   KCOV is expected to help fuzzing the kernel, and while in development has
>   already found a number of issues. It is required for the syzkaller system
>   call fuzzer [1]. Other kernel fuzzers could also make use of it, either
>   with the current interface, or by extending it with new modes.
>   
>   A man page is currently being worked on and is expected to be committed
>   soon, however having the code in the kernel now is useful for other
>   developers to use.
>   
>   [1] https://github.com/google/syzkaller
>   
>   Submitted by:	Mitchell Horne <mhorne063 at gmail.com> (Earlier version)
>   Reviewed by:	kib
>   Testing by:	tuexen
>   Sponsored by:	DARPA, AFRL
>   Sponsored by:	The FreeBSD Foundation (Mitchell Horne)
>   Differential Revision:	https://reviews.freebsd.org/D14599
>
> Added:
>   head/sys/kern/kern_kcov.c   (contents, props changed)
>   head/sys/sys/kcov.h   (contents, props changed)
>   head/tests/sys/kern/kcov.c   (contents, props changed)
> Modified:
>   head/sys/amd64/conf/GENERIC
>   head/sys/arm64/conf/GENERIC
>   head/sys/conf/files
>   head/sys/conf/kern.pre.mk
>   head/sys/conf/options
>   head/sys/kern/kern_thread.c
>   head/sys/sys/proc.h
>   head/tests/sys/kern/Makefile
>
[...]
> Modified: head/sys/sys/proc.h
> =============================================================================
> =
> --- head/sys/sys/proc.h	Sat Jan 12 11:14:59 2019	(r342961)
> +++ head/sys/sys/proc.h	Sat Jan 12 11:21:28 2019	(r342962)
> @@ -175,6 +175,7 @@ struct filecaps;
>  struct filemon;
>  struct kaioinfo;
>  struct kaudit_record;
> +struct kcov_info;
>  struct kdtrace_proc;
>  struct kdtrace_thread;
>  struct mqueue_notifier;
> @@ -300,6 +301,7 @@ struct thread {
>  	sbintime_t	td_sleeptimo;	/* (t) Sleep timeout. */
>  	int		td_rtcgen;	/* (s) rtc_generation of abs. sleep */
>  	size_t		td_vslock_sz;	/* (k) amount of vslock-ed space */
> +	struct kcov_info *td_kcov_info;	/* (*) Kernel code coverage data */
>  #define	td_endzero td_sigmask
>  
>  /* Copied during fork1() or create_thread(). */
>

This breaks 32-bit builds (see jenkins email to recent committers from 
this morning).

Inserting this here and calculating offsets for 64-bit platforms 
without taking into consideration 32-bit is the reason why. Maybe we 
should consider deorbit of 32-bit platforms sooner than later.


-- 
Cheers,
Cy Schubert <Cy.Schubert at cschubert.com>
FreeBSD UNIX:  <cy at FreeBSD.org>   Web:  http://www.FreeBSD.org

	The need of the many outweighs the greed of the few.