On Fri, Aug 19, 2016 at 12:50:49PM +0100, Ben Hutchings wrote:
> >> > > > everything using mozilla-js).
> >> [...]
> >>
> >> Could we possibly work around that by reducing
> >> CONFIG_ARCH_MMAP_RND_BITS_MAX? (That's not directly configurable; it
> >> requires patching arch/arm64/Kconfig.)
> >
> >I think this would be opening up a real can of worms. Not all sizes
> >are supported by the architecture, and only certain VA_BITS/pagesize
> >combinations work in the kernel.
> >
> >We could switch to 42-bit VA, but that would require switching to 64K
> >pagesize, which would be an even huger can.
>
> I'm not suggesting using any unusual page table configuration. Just
> reducing the ASLR range that is currently implied by a 48-bit VA.
But would that help anything?
Even if you don't allocate to the top bits, if they're used for
tagging, you'll still segfault.
/
Leif
