Re: [Xen-devel] [PATCH v2 23/24] xen/arm: mm: Handle permission flags when adding a new mapping

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 12 Sep 2017, Julien Grall wrote:
> Currently, all the new mappings will be read-write non-executable. Allow the
> caller to use other permissions.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> 
> ---
>     Changes in v2:
>         - Switch the runtime check to a BUG_ON()

Since you are at it, could you please also turn the other runtime check
few lines below into another BUG_ON (under MODIFY)?


> ---
>  xen/arch/arm/mm.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 8a56f37821..a6b228ba9b 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -1022,6 +1022,9 @@ static int create_xen_entries(enum xenmap_operation op,
>                  if ( op == RESERVE )
>                      break;
>                  pte = mfn_to_xen_entry(mfn, PAGE_AI_MASK(flags));
> +                pte.pt.ro = PAGE_RO_MASK(flags);
> +                pte.pt.xn = PAGE_XN_MASK(flags);
> +                BUG_ON(!pte.pt.ro && !pte.pt.xn);
>                  pte.pt.table = 1;
>                  write_pte(entry, pte);
>                  break;
> -- 
> 2.11.0
> 

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