Re: [Xen-devel] [PATCH 2/3] xen: arm: correctly handle continuations for 64-bit guests

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 25/03/15 15:34, Ian Campbell wrote:
> The 64-bit ABI is different to 32-bit:
>
>   - uses x16 as the op register rather than r12.
>   - arguments in x0..x5 and not r0..r5. Using rN here potentially
>     truncates.
>   - return value goes in x0, not r0.
>
> Hypercalls can only be made directly from kernel space, so checking
> the domain's size is sufficient.
>
> The update of regs->pc is duplicated in both halves because the 32-bit
> case is going to need fixing to handle Thumb mode (next patch).
>
> Spotted due to spurious -EFAULT when destroying a domain, due to the
> hypercall's pointer argument being truncated. I'm unclear why I am
> only seeing this now.
>
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Almost certainly 15e0aac6fe76be6a710a8e6d3da610d437903266 which changed 
XEN_DOMCTL_destroydomain to use continuations rather than repeated 
hypercalls.
~Andrew

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