[PATCH v9 4/6] ARM: add vdso user-space code

Hi Nathan,

On Fri, Aug 22, 2014 at 10:52:29PM +0100, Nathan Lynch wrote:

Place vdso-related user-space code in arch/arm/kernel/vdso/.

It is almost completely written in C with some assembly helpers to
load the data page address, sample the counter, and fall back to
system calls when necessary.

I'm still a bit puzzled as to how we can implement a compat version of this
for a 32-bit userspace running under a 64-bit kernel. Maybe the answer is
that we don't care enough (programs will still work fine without it), but if
we did want to then we're going to need to build the kernel with two
toolchains and it gets really horrible.

Do you have any ideas?

Will