Date: Sat, 12 Jan 2019 13:16:30 -0700 From: Warner Losh <imp@bsdimp.com> To: Cy Schubert <Cy.Schubert@cschubert.com> Cc: Andrew Turner <andrew@freebsd.org>, src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r342962 - in head: sys/amd64/conf sys/arm64/conf sys/conf sys/kern sys/sys tests/sys/kern Message-ID: <CANCZdfpRybhBOaibzrfD3M-owSaQQVF33beUx_qY3KzLAOLPYQ@mail.gmail.com> In-Reply-To: <201901122013.x0CKDhjA064204@slippy.cwsent.com> References: <andrew@FreeBSD.org> <201901121121.x0CBLSiv058912@repo.freebsd.org> <201901122013.x0CKDhjA064204@slippy.cwsent.com>
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On Sat, Jan 12, 2019 at 1:14 PM Cy Schubert <Cy.Schubert@cschubert.com> wrote: > In message <201901121121.x0CBLSiv058912@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@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. Warner
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