On 04.10.2025 00:53, Andrew Cooper wrote:
> FRED and IDT differ by a Supervisor Token on the base of the shstk. This
> means that switch_stack_and_jump() needs to discard one extra word when FRED
> is active.
>
> Fix a typo in the parameter name, which should be shstk_base.
>
> Signed-off-by: Andrew Cooper <[email protected]>
> Reviewed-by: Jan Beulich <[email protected]>
> ---
> CC: Jan Beulich <[email protected]>
> CC: Roger Pau Monné <[email protected]>
>
> Leave as $%c. Otherwise it doesn't assemble correctly presented with $$24568
> to parse as an instruction immediate.
I don't follow. Where would the 2nd $ come from if you write ...
> --- a/xen/arch/x86/include/asm/current.h
> +++ b/xen/arch/x86/include/asm/current.h
> @@ -154,7 +154,9 @@ unsigned long get_stack_dump_bottom (unsigned long sp);
> "rdsspd %[ssp];" \
> "cmp $1, %[ssp];" \
> "je .L_shstk_done.%=;" /* CET not active? Skip. */ \
> - "mov $%c[skstk_base], %[val];" \
> + ALTERNATIVE("mov $%c[shstk_base], %[val];", \
> + "mov $%c[shstk_base] + 8, %[val];", \
> + X86_FEATURE_XEN_FRED) \
ALTERNATIVE("mov %[shstk_base], %[val];", \
"mov %[shstk_base] + 8, %[val];", \
X86_FEATURE_XEN_FRED) \
Jan
