[PATCH V3 1/5] mm: mmap: Allow for "high" userspace addresses

[Steve.Capper@arm.com (Steve Capper)]

On Fri, Nov 23, 2018 at 06:17:44PM +0000, Catalin Marinas wrote:
> On Wed, Nov 14, 2018 at 01:39:16PM +0000, Steve Capper wrote:
> > This patch adds support for "high" userspace addresses that are
> > optionally supported on the system and have to be requested via a hint
> > mechanism ("high" addr parameter to mmap).
> > 
> > Architectures such as powerpc and x86 achieve this by making changes to
> > their architectural versions of arch_get_unmapped_* functions. However,
> > on arm64 we use the generic versions of these functions.
> > 
> > Rather than duplicate the generic arch_get_unmapped_* implementations
> > for arm64, this patch instead introduces two architectural helper macros
> > and applies them to arch_get_unmapped_*:
> >  arch_get_mmap_end(addr) - get mmap upper limit depending on addr hint
> >  arch_get_mmap_base(addr, base) - get mmap_base depending on addr hint
> > 
> > If these macros are not defined in architectural code then they default
> > to (TASK_SIZE) and (base) so should not introduce any behavioural
> > changes to architectures that do not define them.
> > 
> > Signed-off-by: Steve Capper <steve.capper@arm.com>
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Thanks!