On Mon, Jun 24, 2019 at 04:33:00PM +0200, Andrey Konovalov wrote: > --- /dev/null > +++ b/tools/testing/selftests/arm64/tags_test.c > @@ -0,0 +1,29 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include <stdio.h> > +#include <stdlib.h> > +#include <unistd.h> > +#include <stdint.h> > +#include <sys/prctl.h> > +#include <sys/utsname.h> > + > +#define SHIFT_TAG(tag) ((uint64_t)(tag) << 56) > +#define SET_TAG(ptr, tag) (((uint64_t)(ptr) & ~SHIFT_TAG(0xff)) | \ > + SHIFT_TAG(tag)) > + > +int main(void) > +{ > + static int tbi_enabled = 0; > + struct utsname *ptr, *tagged_ptr; > + int err; > + > + if (prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0) == 0) > + tbi_enabled = 1; Nitpick: with the latest prctl() patch, you can skip the last three arguments as they are ignored. Either way: Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>