From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/5349 Path: news.gmane.org!not-for-mail From: Russell King - ARM Linux Newsgroups: gmane.linux.lib.musl.general,gmane.linux.ports.arm.kernel Subject: Re: Thread pointer changes Date: Sat, 28 Jun 2014 00:20:57 +0100 Message-ID: <20140627232056.GZ32514@n2100.arm.linux.org.uk> References: <20140610072835.GA8466@brightrain.aerifal.cx> <20140611145533.GT179@brightrain.aerifal.cx> <53ADC5B1.6080905@amacapital.net> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1403911279 30545 80.91.229.3 (27 Jun 2014 23:21:19 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 27 Jun 2014 23:21:19 +0000 (UTC) Cc: musl@lists.openwall.com, linux-arm-kernel@lists.infradead.org, Kees Cook To: Andy Lutomirski Original-X-From: musl-return-5354-gllmg-musl=m.gmane.org@lists.openwall.com Sat Jun 28 01:21:13 2014 Return-path: Envelope-to: gllmg-musl@plane.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1X0fSC-0000cy-0X for gllmg-musl@plane.gmane.org; Sat, 28 Jun 2014 01:21:12 +0200 Original-Received: (qmail 14323 invoked by uid 550); 27 Jun 2014 23:21:11 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 14315 invoked from network); 27 Jun 2014 23:21:11 -0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=arm.linux.org.uk; s=pandora; h=Sender:In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date; bh=Y9by6/+sePXot27yTSKZZkKqx8a+zOukuMA5+ZpZwnA=; b=ZvHCKtuGiOAKQLI6GFriVdc8tBThWzGdTmx/mKiZ1F0gTTG8/nAKLVw2yxwVTAfZJ0JJw9ZRB33ctloWizCB266BthRwX9suIsGUcagb47uXA9J/BjvqzfVDjCe1SDmaiMcKAem6EEWFqRL3sGVkT2keQ5oCnFPCu4hRlUaPYpQ=; Content-Disposition: inline In-Reply-To: <53ADC5B1.6080905@amacapital.net> User-Agent: Mutt/1.5.19 (2009-01-05) Original-Sender: Russell King - ARM Linux Xref: news.gmane.org gmane.linux.lib.musl.general:5349 gmane.linux.ports.arm.kernel:336499 Archived-At: Right, I'm done on this thread for the weekend - I will not be answering another message on this subject until next week. In summary: I've shown that this isn't as big a problem as first thought, because there's ways that a libc can trivially detect the CPU that it is running on, and from that know what instructions are available to it. I've indicated that the kuser helpers are always provided when there is no hardware TLS support, which corresponds with a minimum ARM architecture of version 6K, and v6k has the atomic instructions. I've said that we're not going to move kuser helpers to a randomised address, and given strong reasons why not. I've indicated where the CPU architecture can be retrieved from, and used to determine the availability of other instructions. I've indicated that the ELF HWCAPs can be used to further refine the available instruction information. That should be sufficient to answer all the questions raised. Please wait until next week before asking further questions, thanks. -- FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly improving, and getting towards what was expected from it.