Re: [Xen-devel] [PATCH v2 2/2] xen/arm: alternative: Make it possible to patch outside of the hypervisor

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Sep 07, 2016 at 01:50:44PM +0100, Julien Grall wrote:
> With livepatch the alternatives that should be patched are outside of
> the Xen hypervisor _start -> _end. The current code is assuming that
> only Xen could be patched and therefore will explode when a payload
> contains alternatives.
> 
> Given that alt_instr contains a relative offset, the function
> __apply_alternatives could directly take in parameter the virtual
> address of the alt_instr set of the re-mapped region. So we can mandate
> the callers of __apply_alternatives to provide use with a region that has
> read-write access.
> 
> The only caller that will patch directly the Xen binary is the function
> __apply_alternatives_multi_stop. The other caller apply_alternatives
> will work on the payload which will still have read-write access at that
> time.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> 
> ---
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

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