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Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)
- From: Florian Weimer <fweimer at redhat dot com>
- To: Andy Lutomirski <luto at amacapital dot net>, OndÅej BÃlka <neleai at seznam dot cz>
- Cc: Linus Torvalds <torvalds at linux-foundation dot org>, Mathieu Desnoyers <mathieu dot desnoyers at efficios dot com>, Ben Maurer <bmaurer at fb dot com>, Paul Turner <pjt at google dot com>, Andrew Hunter <ahh at google dot com>, Peter Zijlstra <peterz at infradead dot org>, Ingo Molnar <mingo at redhat dot com>, rostedt <rostedt at goodmis dot org>, "Paul E. McKenney" <paulmck at linux dot vnet dot ibm dot com>, Josh Triplett <josh at joshtriplett dot org>, Lai Jiangshan <laijs at cn dot fujitsu dot com>, Andrew Morton <akpm at linux-foundation dot org>, linux-api <linux-api at vger dot kernel dot org>, libc-alpha <libc-alpha at sourceware dot org>
- Date: Mon, 20 Jul 2015 10:35:40 +0200
- Subject: Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)
- Authentication-results: sourceware.org; auth=none
- References: <1436724386-30909-1-git-send-email-mathieu dot desnoyers at efficios dot com> <5CDDBDF2D36D9F43B9F5E99003F6A0D48D5F39C6 at PRN-MBX02-1 dot TheFacebook dot com> <587954201 dot 31 dot 1436808992876 dot JavaMail dot zimbra at efficios dot com> <5CDDBDF2D36D9F43B9F5E99003F6A0D48D5F5DA0 at PRN-MBX02-1 dot TheFacebook dot com> <549319255 dot 383 dot 1437070088597 dot JavaMail dot zimbra at efficios dot com> <CALCETrWEKE=mow3vVh7C4r8CuGy_d5VOEz7KkpijuR5cpBfFtg at mail dot gmail dot com> <CA+55aFz-VBnEKh0SPKgu8xV5=Zb+=6odybVUDoOYOknshbcFJA at mail dot gmail dot com> <20150717232836 dot GA13604 at domone> <CALCETrVY=kjeA_4pazy3BL+ekfcV6WHKw8e3z-LBxx_uP1bw2Q at mail dot gmail dot com>
On 07/18/2015 01:33 AM, Andy Lutomirski wrote:
> 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.
--
Florian Weimer / Red Hat Product Security