* [PATCH v1 1/1] x86/kernel: Increase kcov coverage under arch/x86/kernel folder [not found] <cover.1688460800.git.pengfei.xu@intel.com> @ 2023-07-04 9:00 ` Pengfei Xu 2023-07-05 4:28 ` Dmitry Vyukov 0 siblings, 1 reply; 3+ messages in thread From: Pengfei Xu @ 2023-07-04 9:00 UTC (permalink / raw) To: dvyukov, nogikh, linux-kernel Cc: Pengfei Xu, Heng Su, syzkaller, keescook, Mehta Sohil, kirill.shutemov, akpm Currently kcov instrument is disabled for object files under arch/x86/kernel folder. For object files under arch/x86/kernel, actually just disabling the kcov instrument of files:"head32.o or head64.o and sev.o" could achieve successful booting and provide kcov coverage for object files that do not disable kcov instrument. The additional kcov coverage collected from arch/x86/kernel folder helps kernel fuzzing efforts to find bugs. Link to related improvement discussion is below: https://groups.google.com/g/syzkaller/c/Dsl-RYGCqs8/m/x-tfpTyFBAAJ Related ticket is as follow: https://bugzilla.kernel.org/show_bug.cgi?id=198443 Signed-off-by: Pengfei Xu <pengfei.xu@intel.com> --- arch/x86/kernel/Makefile | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 4070a01c11b7..00df34c263cc 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -33,11 +33,10 @@ KCSAN_SANITIZE := n KMSAN_SANITIZE_head$(BITS).o := n KMSAN_SANITIZE_nmi.o := n -# If instrumentation of this dir is enabled, boot hangs during first second. -# Probably could be more selective here, but note that files related to irqs, -# boot, dumpstack/stacktrace, etc are either non-interesting or can lead to -# non-deterministic coverage. -KCOV_INSTRUMENT := n +# If instrumentation of the following files is enabled, boot hangs during +# first second. +KCOV_INSTRUMENT_head$(BITS).o := n +KCOV_INSTRUMENT_sev.o := n CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace -- 2.31.1 ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v1 1/1] x86/kernel: Increase kcov coverage under arch/x86/kernel folder 2023-07-04 9:00 ` [PATCH v1 1/1] x86/kernel: Increase kcov coverage under arch/x86/kernel folder Pengfei Xu @ 2023-07-05 4:28 ` Dmitry Vyukov 2023-07-05 11:38 ` Pengfei Xu 0 siblings, 1 reply; 3+ messages in thread From: Dmitry Vyukov @ 2023-07-05 4:28 UTC (permalink / raw) To: Pengfei Xu Cc: nogikh, linux-kernel, Heng Su, syzkaller, keescook, Mehta Sohil, kirill.shutemov, akpm On Tue, 4 Jul 2023 at 10:58, Pengfei Xu <pengfei.xu@intel.com> wrote: > > Currently kcov instrument is disabled for object files under arch/x86/kernel > folder. > For object files under arch/x86/kernel, actually just disabling the kcov > instrument of files:"head32.o or head64.o and sev.o" could achieve > successful booting and provide kcov coverage for object files that do not > disable kcov instrument. > The additional kcov coverage collected from arch/x86/kernel folder helps > kernel fuzzing efforts to find bugs. > > Link to related improvement discussion is below: > https://groups.google.com/g/syzkaller/c/Dsl-RYGCqs8/m/x-tfpTyFBAAJ > Related ticket is as follow: > https://bugzilla.kernel.org/show_bug.cgi?id=198443 > > Signed-off-by: Pengfei Xu <pengfei.xu@intel.com> Reviewed-and-tested-by: Dmitry Vyukov <dvyukov@google.com> I've run a local syzkaller instance with this and I don't see any additional kernel bugs caused by this and I see coverage in arch/x86/kernel/* now, in particular, dumpstack.c, perf_regs.c, signal.c. > --- > arch/x86/kernel/Makefile | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile > index 4070a01c11b7..00df34c263cc 100644 > --- a/arch/x86/kernel/Makefile > +++ b/arch/x86/kernel/Makefile > @@ -33,11 +33,10 @@ KCSAN_SANITIZE := n > KMSAN_SANITIZE_head$(BITS).o := n > KMSAN_SANITIZE_nmi.o := n > > -# If instrumentation of this dir is enabled, boot hangs during first second. > -# Probably could be more selective here, but note that files related to irqs, > -# boot, dumpstack/stacktrace, etc are either non-interesting or can lead to > -# non-deterministic coverage. > -KCOV_INSTRUMENT := n > +# If instrumentation of the following files is enabled, boot hangs during > +# first second. > +KCOV_INSTRUMENT_head$(BITS).o := n > +KCOV_INSTRUMENT_sev.o := n > > CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace > > -- > 2.31.1 > ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v1 1/1] x86/kernel: Increase kcov coverage under arch/x86/kernel folder 2023-07-05 4:28 ` Dmitry Vyukov @ 2023-07-05 11:38 ` Pengfei Xu 0 siblings, 0 replies; 3+ messages in thread From: Pengfei Xu @ 2023-07-05 11:38 UTC (permalink / raw) To: Dmitry Vyukov Cc: nogikh, linux-kernel, Heng Su, syzkaller, keescook, Mehta Sohil, kirill.shutemov, akpm Hi Dmitry, On 2023-07-05 at 06:28:10 +0200, Dmitry Vyukov wrote: > On Tue, 4 Jul 2023 at 10:58, Pengfei Xu <pengfei.xu@intel.com> wrote: > > > > Currently kcov instrument is disabled for object files under arch/x86/kernel > > folder. > > For object files under arch/x86/kernel, actually just disabling the kcov > > instrument of files:"head32.o or head64.o and sev.o" could achieve > > successful booting and provide kcov coverage for object files that do not > > disable kcov instrument. > > The additional kcov coverage collected from arch/x86/kernel folder helps > > kernel fuzzing efforts to find bugs. > > > > Link to related improvement discussion is below: > > https://groups.google.com/g/syzkaller/c/Dsl-RYGCqs8/m/x-tfpTyFBAAJ > > Related ticket is as follow: > > https://bugzilla.kernel.org/show_bug.cgi?id=198443 > > > > Signed-off-by: Pengfei Xu <pengfei.xu@intel.com> > > Reviewed-and-tested-by: Dmitry Vyukov <dvyukov@google.com> > > I've run a local syzkaller instance with this and I don't see any > additional kernel bugs caused by this and I see coverage in > arch/x86/kernel/* now, in particular, dumpstack.c, perf_regs.c, > signal.c. Thanks for your tag! Yes, it can cover more code in arch/x86/kernel/. Best Regards, Thanks! > > > > --- > > arch/x86/kernel/Makefile | 9 ++++----- > > 1 file changed, 4 insertions(+), 5 deletions(-) > > > > diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile > > index 4070a01c11b7..00df34c263cc 100644 > > --- a/arch/x86/kernel/Makefile > > +++ b/arch/x86/kernel/Makefile > > @@ -33,11 +33,10 @@ KCSAN_SANITIZE := n > > KMSAN_SANITIZE_head$(BITS).o := n > > KMSAN_SANITIZE_nmi.o := n > > > > -# If instrumentation of this dir is enabled, boot hangs during first second. > > -# Probably could be more selective here, but note that files related to irqs, > > -# boot, dumpstack/stacktrace, etc are either non-interesting or can lead to > > -# non-deterministic coverage. > > -KCOV_INSTRUMENT := n > > +# If instrumentation of the following files is enabled, boot hangs during > > +# first second. > > +KCOV_INSTRUMENT_head$(BITS).o := n > > +KCOV_INSTRUMENT_sev.o := n > > > > CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace > > > > -- > > 2.31.1 > > ^ permalink raw reply [flat|nested] 3+ messages in thread
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[not found] <cover.1688460800.git.pengfei.xu@intel.com>
2023-07-04 9:00 ` [PATCH v1 1/1] x86/kernel: Increase kcov coverage under arch/x86/kernel folder Pengfei Xu
2023-07-05 4:28 ` Dmitry Vyukov
2023-07-05 11:38 ` Pengfei Xu
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