From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 23 Feb 2010 22:35:27 +0100 (CET) Received: from localhost.localdomain ([127.0.0.1]:34239 "EHLO h5.dl5rb.org.uk" rhost-flags-OK-OK-OK-FAIL) by eddie.linux-mips.org with ESMTP id S1492409Ab0BWVfY (ORCPT ); Tue, 23 Feb 2010 22:35:24 +0100 Received: from h5.dl5rb.org.uk (localhost.localdomain [127.0.0.1]) by h5.dl5rb.org.uk (8.14.3/8.14.3) with ESMTP id o1NLZKr2020289; Tue, 23 Feb 2010 22:35:20 +0100 Received: (from ralf@localhost) by h5.dl5rb.org.uk (8.14.3/8.14.3/Submit) id o1NLZI0n020288; Tue, 23 Feb 2010 22:35:18 +0100 Date: Tue, 23 Feb 2010 22:35:18 +0100 From: Ralf Baechle To: Manuel Lauss Cc: David Daney , linux-mips@linux-mips.org Subject: Re: [PATCH 2/3] MIPS: Preliminary vdso. Message-ID: <20100223213518.GA19715@linux-mips.org> References: <1266538385-29088-1-git-send-email-ddaney@caviumnetworks.com> <1266538385-29088-3-git-send-email-ddaney@caviumnetworks.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-08-17) 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: 26005 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: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Tue, Feb 23, 2010 at 09:40:38PM +0100, Manuel Lauss wrote: > > This is a preliminary patch to add a vdso to all user processes. > > Still missing are ELF headers and .eh_frame information.  But it is > > enough to allow us to move signal trampolines off of the stack.  Note > > that emulation of branch delay slots in the FPU emulator still > > requires the stack. > > > > We allocate a single page (the vdso) and write all possible signal > > trampolines into it.  The stack is moved down by one page and the vdso > > is mapped into this space. > > Is there anything special required (i.e. special glibc, ..) to make use of these > fine patches? No - the way the signal handlers return is almost entirely hidden from userland. Only a few applications that have the need to unwind beyond the signal stackframe may run into problems and have to be updated and GDB is one of those that we identified. Ralf