Re: [PATCH v2] x86/xen/64: Rearrange the SYSCALL entries

[Juergen Gross]

On 08/08/17 05:59, Andy Lutomirski wrote:
> Xen's raw SYSCALL entries are much less weird than native.  Rather
> than fudging them to look like native entries, use the Xen-provided
> stack frame directly.
> 
> This lets us eliminate entry_SYSCALL_64_after_swapgs and two uses of
> the SWAPGS_UNSAFE_STACK paravirt hook.  The SYSENTER code would
> benefit from similar treatment.
> 
> This makes one change to the native code path: the compat
> instruction that clears the high 32 bits of %rax is moved slightly
> later.  I'd be surprised if this affects performance at all.
> 
> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Tested-by: Juergen Gross <jgross@xxxxxxxx>


Thanks,

Juergen