Re: [Xen-devel] [PATCH v2 1/2] xen/PVH: Set up GS segment for stack canary

[Jan Beulich]

>>> On 09.05.18 at 22:33, <boris.ostrovsky@xxxxxxxxxx> wrote:
> @@ -64,6 +67,17 @@ ENTRY(pvh_start_xen)
>  	mov %eax,%es
>  	mov %eax,%ss
>  
> +	/* Set base address in stack canary descriptor. */
> +	movl _pa(gdt_start),%eax
> +	movl $_pa(canary),%ecx
> +	movw %cx, (PVH_GDT_ENTRY_CANARY * 8) + 0(%eax)
> +	shrl $16, %ecx
> +	movb %cl, (PVH_GDT_ENTRY_CANARY * 8) + 2(%eax)
> +	movb %ch, (PVH_GDT_ENTRY_CANARY * 8) + 5(%eax)

Is this meaningful / correct for the 64-bit case? I'd rather expect you to
write the GS base address MSR there.

Jan