On Mon, 2026-06-15 at 14:51 -0500, Bill Roberts wrote:
> One should not be able to use ARCH_SHSTK_UNLOCK via arch_prctl to twiddle
> feature bits, test that this is the case.
>
> Signed-off-by: Bill Roberts <[email protected]>
> ---
> tools/testing/selftests/x86/test_shadow_stack.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/tools/testing/selftests/x86/test_shadow_stack.c
> b/tools/testing/selftests/x86/test_shadow_stack.c
> index 21af54d5f4ea..82a5fefa9df5 100644
> --- a/tools/testing/selftests/x86/test_shadow_stack.c
> +++ b/tools/testing/selftests/x86/test_shadow_stack.c
> @@ -979,6 +979,14 @@ int main(int argc, char *argv[])
> {
> int ret = 0;
>
> + /* test that we can't use unlock to set shadow stack */
> + if (!ARCH_PRCTL(ARCH_SHSTK_UNLOCK, ARCH_SHSTK_SHSTK)) {
> + printf("[SKIP]\tCould enable Shadow stack via UNLOCK\n");
> + return 1;
> + }
More generally, we should not be able to use ARCH_SHSTK_UNLOCK here. Can we make
the comment generic and not checking for a specific bug? Because it does more
than that.
> +
> + printf("[OK]\tCouldn't enable Shadow stack via UNLOCK\n");
> +
> if (ARCH_PRCTL(ARCH_SHSTK_ENABLE, ARCH_SHSTK_SHSTK)) {
> printf("[SKIP]\tCould not enable Shadow stack\n");
> return 1;
