On Wed, Dec 9, 2020 at 11:01 AM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > > Both KCOV and UBSAN use compiler instrumentation. If UBSAN detects a bug > in KCOV, it may cause infinite recursion via printk and other common > functions. We already don't instrument KCOV with KASAN/KCSAN for this > reason, don't instrument it with UBSAN as well. > > As a side effect this also resolves the following gcc warning: > > conflicting types for built-in function '__sanitizer_cov_trace_switch'; > expected 'void(long unsigned int, void *)' [-Wbuiltin-declaration-mismatch] > > It's only reported when kcov.c is compiled with any of the sanitizers > enabled. Size of the arguments is correct, it's just that gcc uses 'long' > on 64-bit arches and 'long long' on 32-bit arches, while kernel type is > always 'long long'. > > Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> > Suggested-by: Marco Elver <elver@xxxxxxxxxx> > Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > --- > kernel/Makefile | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/Makefile b/kernel/Makefile > index aac15aeb9d69..efa42857532b 100644 > --- a/kernel/Makefile > +++ b/kernel/Makefile > @@ -34,8 +34,11 @@ KCOV_INSTRUMENT_extable.o := n > KCOV_INSTRUMENT_stacktrace.o := n > # Don't self-instrument. > KCOV_INSTRUMENT_kcov.o := n > +# If sanitizers detect any issues in kcov, it may lead to recursion > +# via printk, etc. > KASAN_SANITIZE_kcov.o := n > KCSAN_SANITIZE_kcov.o := n > +UBSAN_SANITIZE_kcov.o := n > CFLAGS_kcov.o := $(call cc-option, -fno-conserve-stack) -fno-stack-protector > > obj-y += sched/ > -- > 2.29.2.576.ga3fc446d84-goog > Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
