Messages in this thread | | | Date | Mon, 7 Aug 2023 12:58:03 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH RESEND v1 1/1] x86/kernel: Increase kcov coverage under arch/x86/kernel folder |
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On Mon, 31 Jul 2023 11:04:18 +0800 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 > > ... > > --- 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
This patch exposes (but probably doesn't cause) an objtool warning:
arch/x86/kernel/traps.o: warning: objtool: ibt_selftest+0x18: sibling call from callable instruction with modified stack frame
gcc-12.2.0, x86_64 allmodconfig.
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