From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 13 Nov 2007 14:47:07 +0000 (GMT) Received: from dns0.mips.com ([63.167.95.198]:62648 "EHLO dns0.mips.com") by ftp.linux-mips.org with ESMTP id S20026641AbXKMOq5 (ORCPT ); Tue, 13 Nov 2007 14:46:57 +0000 Received: from mercury.mips.com (mercury [192.168.64.101]) by dns0.mips.com (8.12.11/8.12.11) with ESMTP id lADEciPK026008; Tue, 13 Nov 2007 06:38:44 -0800 (PST) Received: from grendel (grendel [192.168.236.16]) by mercury.mips.com (8.13.5/8.13.5) with SMTP id lADEd9kP006753; Tue, 13 Nov 2007 06:39:10 -0800 (PST) Message-ID: <019e01c82602$f5463bf0$10eca8c0@grendel> From: "Kevin D. Kissell" To: "Franck Bui-Huu" , "Ralf Baechle" Cc: "Andrew Haley" , "David Daney" , , "Richard Sandiford" , References: <473957B6.3030202@avtrex.com> <18233.36645.232058.964652@zebedee.pink> <20071113121036.GA6582@linux-mips.org> Subject: Re: Cannot unwind through MIPS signal frames with ICACHE_REFILLS_WORKAROUND_WAR Date: Tue, 13 Nov 2007 15:37:39 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1807 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1896 Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 17484 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: kevink@mips.com Precedence: bulk X-list: linux-mips Franck a dit: > > Another reason is to get rid of the classic trampoline the kernel installs > > on the stack. On some multiprocessor systems it requires a cacheflush > > operation to be performed on all processors which is expensive. Having > > the trampoline in a vDSO would solve that. > > > > And the stack wouldn't need to have exec permission anymore. True, though it should perhaps be noted that currently it's only on 4KSc/Sd systems (which I know you work on) where it's even possible for the stack *not* to have exec permissions, since the classical MIPS MMU gives execute permission to any page that is readable. Regards, Kevin K. From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dns0.mips.com ([63.167.95.198]:62648 "EHLO dns0.mips.com") by ftp.linux-mips.org with ESMTP id S20026641AbXKMOq5 (ORCPT ); Tue, 13 Nov 2007 14:46:57 +0000 Message-ID: <019e01c82602$f5463bf0$10eca8c0@grendel> From: "Kevin D. Kissell" References: <473957B6.3030202@avtrex.com> <18233.36645.232058.964652@zebedee.pink> <20071113121036.GA6582@linux-mips.org> Subject: Re: Cannot unwind through MIPS signal frames with ICACHE_REFILLS_WORKAROUND_WAR Date: Tue, 13 Nov 2007 15:37:39 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-Path: Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org To: Franck Bui-Huu , Ralf Baechle Cc: Andrew Haley , David Daney , linux-mips@linux-mips.org, Richard Sandiford , gcc@gcc.gnu.org Message-ID: <20071113143739.DTtxlTrKBV8XKm9Gm7Asn8Luqg6o1B6Ejz3h5tbsYHU@z> Franck a dit: > > Another reason is to get rid of the classic trampoline the kernel installs > > on the stack. On some multiprocessor systems it requires a cacheflush > > operation to be performed on all processors which is expensive. Having > > the trampoline in a vDSO would solve that. > > > > And the stack wouldn't need to have exec permission anymore. True, though it should perhaps be noted that currently it's only on 4KSc/Sd systems (which I know you work on) where it's even possible for the stack *not* to have exec permissions, since the classical MIPS MMU gives execute permission to any page that is readable. Regards, Kevin K.