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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: Mathieu Desnoyers <mathieu dot desnoyers at efficios dot com>, Linus Torvalds <torvalds at linux-foundation dot org>
- Cc: Andy Lutomirski <luto at amacapital dot net>, Ben Maurer <bmaurer at fb dot com>, Ingo Molnar <mingo at redhat dot com>, libc-alpha <libc-alpha at sourceware dot org>, Andrew Morton <akpm at linux-foundation dot org>, linux-api <linux-api at vger dot kernel dot org>, OndÅej BÃlka <neleai at seznam dot cz>, 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>, Paul Turner <pjt at google dot com>, Andrew Hunter <ahh at google dot com>, Peter Zijlstra <peterz at infradead dot org>
- Date: Tue, 21 Jul 2015 10:01:26 +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> <55ACB2DC dot 5010503 at redhat dot com> <CALCETrV9Vp5UUOb3e_R5tphyE-urBgTwQR2pFWUOOFnHqWXHKQ at mail dot gmail dot com> <55AD14A4 dot 6030101 at redhat dot com> <CALCETrUx6wFxmz+9TyW5bNgaMN0q180G8y9YOyq_D41sdhFaRQ at mail dot gmail dot com> <CA+55aFzMJkzydXb7uVv1iSUnp=539d43ghQaonGdzMoF7QLZBA at mail dot gmail dot com> <CALCETrUZ8vB30rdmeoV4JKPUsRnVPvoxXRJ47CEFud2aSF2=Ew at mail dot gmail dot com> <CA+55aFwLZLeeN7UN82dyt=emQcNBc8qZPJAw5iqtAbBwFA7FPQ at mail dot gmail dot com> <2010227315 dot 699 dot 1437438300542 dot JavaMail dot zimbra at efficios dot com>
On 07/21/2015 02:25 AM, Mathieu Desnoyers wrote:
> But I'm inclined to think that some aspect of the question eludes me,
> especially given the amount of interest generated by the gs-segment
> selector approach. What am I missing ?
%gs is not explicitly mentioned in the x86_64 psABI. This probably led
to the assumption that it's unused. I think that's not the right
conclusion to draw.
--
Florian Weimer / Red Hat Product Security