linux-kernel - Re: [PATCH 0/2] x86-64: allow using RIP-relative addressing for per-CPU data

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <545929F9.7010301@amacapital.net>
Date:	Tue, 04 Nov 2014 11:33:13 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Jan Beulich <JBeulich@...e.com>, mingo@...e.hu, tglx@...utronix.de,
	hpa@...or.com
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] x86-64: allow using RIP-relative addressing for per-CPU
 data

On 11/04/2014 12:49 AM, Jan Beulich wrote:
> Observing that per-CPU data (in the SMP case) is reachable by
> exploiting 64-bit address wraparound, these two patches
> arrange for using the one byte shorter RIP-relative addressing
> forms for the majority of per-CPU accesses.
> 
> 1: handle PC-relative relocations on per-CPU data
> 2: use RIP-relative addressing for most per-CPU accesses
> 
> Signed-off-by: Jan Beulich <jbeulich@...e.com>
> 

I'm lost here.  Can you give an example of a physical and virtual
address of an instruction, the address within the gs segment, and why
the relocations are backwards?

--Andy
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/