Date: Sat, 28 Jun 2014 00:20:57 +0100 From: Russell King - ARM Linux <linux@....linux.org.uk> To: Andy Lutomirski <luto@...capital.net> Cc: musl@...ts.openwall.com, linux-arm-kernel@...ts.infradead.org, Kees Cook <keescook@...omium.org> Subject: Re: Thread pointer changes 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.
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