[PATCH 3/5] arm64: compat: Allow signal page to be remapped

[Vincenzo Frascino]

On 3/18/21 5:07 PM, Will Deacon wrote:
> For compatability with 32-bit Arm, allow the compat signal page to be
> remapped via mremap().
> 
> Signed-off-by: Will Deacon <will at kernel.org>

Reviewed-by: Vincenzo Frascino <vincenzo.frascino at arm.com>

> ---
>  arch/arm64/kernel/vdso.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
> index 421411981dc3..16bf0b46fb70 100644
> --- a/arch/arm64/kernel/vdso.c
> +++ b/arch/arm64/kernel/vdso.c
> @@ -271,6 +271,14 @@ enum aarch32_map {
>  static struct page *aarch32_vectors_page __ro_after_init;
>  static struct page *aarch32_sig_page __ro_after_init;
>  
> +static int aarch32_sigpage_mremap(const struct vm_special_mapping *sm,
> +				  struct vm_area_struct *new_vma)
> +{
> +	current->mm->context.sigpage = (void *)new_vma->vm_start;
> +
> +	return 0;
> +}
> +
>  static struct vm_special_mapping aarch32_vdso_maps[] = {
>  	[AA32_MAP_VECTORS] = {
>  		.name	= "[vectors]", /* ABI */
> @@ -279,6 +287,7 @@ static struct vm_special_mapping aarch32_vdso_maps[] = {
>  	[AA32_MAP_SIGPAGE] = {
>  		.name	= "[sigpage]", /* ABI */
>  		.pages	= &aarch32_sig_page,
> +		.mremap	= aarch32_sigpage_mremap,
>  	},
>  	[AA32_MAP_VVAR] = {
>  		.name = "[vvar]",
> 

-- 
Regards,
Vincenzo