Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753938AbXIRIb5 (ORCPT ); Tue, 18 Sep 2007 04:31:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751102AbXIRIbu (ORCPT ); Tue, 18 Sep 2007 04:31:50 -0400 Received: from aun.it.uu.se ([130.238.12.36]:37819 "EHLO aun.it.uu.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751463AbXIRIbt (ORCPT ); Tue, 18 Sep 2007 04:31:49 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <18159.36076.350387.910660@alkaid.it.uu.se> Date: Tue, 18 Sep 2007 10:31:40 +0200 From: Mikael Pettersson To: "Francis Moreau" Cc: "Ulrich Drepper" , linux-kernel@vger.kernel.org Subject: Re: x86_64: vsyscall vs vdso In-Reply-To: <38b2ab8a0709171322v75c5a597of9d90919f456767c@mail.gmail.com> References: <38b2ab8a0709161324p6841c1f9h6f9422b0e6c4b5cd@mail.gmail.com> <38b2ab8a0709170030k2b5dad5dja31edebf12ad9626@mail.gmail.com> <38b2ab8a0709171322v75c5a597of9d90919f456767c@mail.gmail.com> X-Mailer: VM 7.17 under Emacs 20.7.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1084 Lines: 23 Francis Moreau writes: > On 9/17/07, Ulrich Drepper wrote: > > On 9/17/07, Francis Moreau wrote: > > > I think signal trampolines will still need them too. So making > > > vsyscalls configurable doesn't seem to work, does it ? > > > > vsyscalls aren't used for that. We have a restorer in libc and could > > easily use one in the vdso. That's what is done on x86. > > > > Sorry for my ignorance but what' is 'a restorer' ? When the kernel sets up the context for a user-space signal handler, it needs to supply a return address (in a register or on the stack). That's the restorer. The restorer points to a stub that performs sys_{rt_,}sigreturn(). Depending on architecture and kernel version, the restorer stub can be defined by libc, or be provided automatically by the kernel. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/