Re: [RFC PATCH] x86/vdso/32: Add AT_SYSINFO cancellation helpers

From: Andy Lutomirski
Date: Wed Mar 09 2016 - 16:20:12 EST

On Wed, Mar 9, 2016 at 9:58 AM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
> On Tue, Mar 8, 2016 at 5:24 PM, Andy Lutomirski <luto@xxxxxxxxxx> wrote:
>> musl implements system call cancellation in an unusual but clever way.
>> When a thread issues a cancellable syscall, musl issues the syscall
>> through a special thunk that looks roughly like this:
> FWIW, this patch fails disastrously on 64-bit kernels. I fixed it,
> but it needs kbuild changes. I'll send those out to the maintainers.

This version should be okay:

You'll need the parent, too, if you want to test. I'm going to give
the 0day bot a good long chew, since the parent change is a little bit