Re: [PATCH 1/2] x86/arch_prctl: add ARCH_SET_{COMPAT,NATIVE} to change compatible mode

[Dmitry Safonov]

On 04/07/2016 03:21 PM, Cyrill Gorcunov wrote:
> On Thu, Apr 07, 2016 at 03:11:24PM +0300, Dmitry Safonov wrote:
> > On 04/06/2016 09:04 PM, Andy Lutomirski wrote:
> > > [cc Dave Hansen for MPX]
> > Will add x32 support for v2.
> > > I think that you should separate vdso remapping from "personality".
> > > vdso remapping should be available even on native 32-bit builds, which
> > > means that either you can't use arch_prctl for it or you'll have to
> > > wire up arch_prctl as a 32-bit syscall.
> > I cant say, I got your point. Do you mean by vdso remapping
> > mremap for vdso/vvar pages? I think, it should work now.
> > I did remapping for vdso as blob for native x86_64 task differs
> > to compatible task. So it's just changing blobs, address value
> > is there for convenience - I may omit it and just remap
> > different vdso blob at the same place where was previous vdso.
> > I'm not sure, why do we need possibility to map 64-bit vdso blob
> > on native 32-bit builds?
> First of all, thanks a huge for all your comments, Andy!
> Dima, I'm not seeing in patch, don't you have to take
> mm::mmap_sem when walking over VMAs?
I was sure I did, but have missed it, well.
Thanks!
> 	Cyrill


--
Regards,
Dmitry Safonov