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



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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