Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)

On 07/20/2015 05:31 PM, Andy Lutomirski wrote:

On Jul 20, 2015 1:35 AM, "Florian Weimer" [off-list ref] wrote:

quoted

On 07/18/2015 01:33 AM, Andy Lutomirski wrote:

quoted

I think the API should be "set gsbase to x + y*(cpu number)".  On
x86_64, userspace just allocates a big swath of virtual space and
populates it as needed.

This will break WINE and similar applications which use %gs today.

Presumably WINE could just opt not to use this facility, just like
WINE will have to opt out of whatever the enterprise people who want
WRGSBASE were thinking of doing with it.

How is this possible if it's process-global attribute and glibc or some
library in the process starts using it?

-- 
Florian Weimer / Red Hat Product Security