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

[Cy Schubert]

In message <CANCZdfpRybhBOaibzrfD3M-owSaQQVF33beUx_qY3KzLAOLPYQ at mail.gma
il.com>
, Warner Losh writes:
> --000000000000656f96057f487d65
> Content-Type: text/plain; charset="UTF-8"
>
> On Sat, Jan 12, 2019 at 1:14 PM Cy Schubert <Cy.Schubert at cschubert.com>
> wrote:
>
> > 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.
> >
>
> I have the missing mips 64-bit stuff for mips32. i386 already has the
> 64-bit ops, I believe. Arm has them. Just powerpc 32-bit will be left w/o
> them.

The problem here is the KASSERTs in kern_thead.c assert due to the 
32-bit offsets whereby 64-bit builds ok. Check the latest jenkins error 
email for i386.


-- 
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.