On Tue, Oct 17, 2017 at 11:03:15AM +0100, Will Deacon wrote: > On Mon, Oct 16, 2017 at 02:24:38PM +0100, Mark Rutland wrote: > > While we build the LL/SC atomics as a C object file, this does not > > follow the AAPCS. This does not interoperate with other C code, and can > > only be called from special wrapper assembly. > > > > Bulding a kernel with CONFIG_KCOV and CONFIG_ARM64_LSE_ATOMICS results > > in the cmopiler inserting calls to __sanitizer_cov_trace_pc within the > > cmopiler Bulding, too. ;) > > LL/SC atomics. As __sanitizer_cov_trace_pc is built per the AAPCS, these > > calls corrupt register values, resulting in failures at boot time. > > > > Avoid this (and other similar issues) by opting out of all compiler > > instrumentation. We can opt-in to specific instrumentation in future if > > we want to. > > > > Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> > > Cc: Catalin Marinas <catalin.marinas@xxxxxxx> > > Cc: Will Deacon <will.deacon@xxxxxxx> > > --- > > arch/arm64/lib/Makefile | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/arm64/lib/Makefile b/arch/arm64/lib/Makefile > > index a0abc142c92b..af77516f71b2 100644 > > --- a/arch/arm64/lib/Makefile > > +++ b/arch/arm64/lib/Makefile > > @@ -17,5 +17,6 @@ CFLAGS_atomic_ll_sc.o := -fcall-used-x0 -ffixed-x1 -ffixed-x2 \ > > -fcall-saved-x10 -fcall-saved-x11 -fcall-saved-x12 \ > > -fcall-saved-x13 -fcall-saved-x14 -fcall-saved-x15 \ > > -fcall-saved-x18 > > +CC_INSTRUMENT_atomic_ll_sc.o := n > > Does this mean we can lose the "notrace" definition of __LL_SC_INLINE > when generating the out-of-line atomics? Unfortunately not. I'd missed -pg, since that isn't handled in scripts/Makefile.lib, and doesn't seem to have a makefile-level disable. I'll see if that can be remedied. Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
