On 26.11.2021 13:34, Andrew Cooper wrote:
> --- a/xen/include/asm-x86/current.h
> +++ b/xen/include/asm-x86/current.h
> @@ -173,7 +173,6 @@ unsigned long get_stack_dump_bottom (unsigned long sp);
> #define switch_stack_and_jump(fn, instr, constr) \
> ({ \
> unsigned int tmp; \
> - (void)((fn) == (void (*)(void))NULL); \
> BUILD_BUG_ON(!ssaj_has_attr_noreturn(fn)); \
> __asm__ __volatile__ ( \
> SHADOW_STACK_WORK \
> @@ -198,6 +197,7 @@ unsigned long get_stack_dump_bottom (unsigned long sp);
>
> /* The constraint may only specify non-call-clobbered registers. */
> #define reset_stack_and_jump_ind(fn) \
> + (void)((fn) == (void (*)(void))NULL); \
> switch_stack_and_jump(fn, "INDIRECT_JMP %", "b")
>
While the risk of use in a context really requiring it is low, I
still think we'd be better off wrapping the whole thing in ({ })
then.
Jan
