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Re: [Xen-devel] [PATCH] x86/setup: Correct register clobbers for the asm statement when resyncing the stack

On Mon, Oct 20, 2014 at 06:30:07PM +0100, Andrew Cooper wrote:
> When resyncing the stack, the asm statement does not identify %rsi, %rdi and
> %rcx as clobbered by the 'rep movsq'.
> Luckily, there are no functional problems in the generated code.  GCC decides
> not to save any of them before calling boostrap_map(), which clobbers them.
> Correct the clobbers, by listing them as earlyclobber discarded outputs.
> Reported-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: Keir Fraser <keir@xxxxxxx>
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> ---
> I have done an audit of the other uses of `rep $STRINGOP` and this is the only
> asm statement with incorrect clobbers.
> ---
>  xen/arch/x86/setup.c |    9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)

Reviewed-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
Tested-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>


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