Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757790AbZFPKhY (ORCPT ); Tue, 16 Jun 2009 06:37:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751866AbZFPKhN (ORCPT ); Tue, 16 Jun 2009 06:37:13 -0400 Received: from mx1.redhat.com ([66.187.233.31]:46413 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752052AbZFPKhL (ORCPT ); Tue, 16 Jun 2009 06:37:11 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Roland McGrath To: Petr Tesarik X-Fcc: ~/Mail/linus Cc: LKML , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andi Kleen Subject: Re: [PATCH v2 0/8] clean up vdso-layout.lds.S In-Reply-To: Petr Tesarik's message of Tuesday, 16 June 2009 11:55:01 +0200 <1245146101.17481.202.camel@nathan.suse.cz> References: <1244814040-5810-1-git-send-email-ptesarik@suse.cz> <20090616084015.5D2E44B6FD@magilla.sf.frob.com> <1245146101.17481.202.camel@nathan.suse.cz> X-Zippy-Says: .. Now I think I just reached the state of HYPERTENSION that comes JUST BEFORE you see the TOTAL at the SAFEWAY CHECKOUT COUNTER! Message-Id: <20090616103445.A3008D56E@magilla.sf.frob.com> Date: Tue, 16 Jun 2009 03:34:45 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1375 Lines: 41 > Upfront, thank you very much for reviewing the series, Roland! I'm glad to help. > And there currently isn't one. But the writability of the vDSO is a bit > more complicated. True, the VMA is initially mapped read-only, but it is > possible to make it writable using mprotect(). Except for CONFIG_COMPAT_VDSO on X86_32. > You may also set an > INT3-style breakpoint in the vDSO area. So, it's all about policy. If > there were any demand to make the vDSO writable, it could be done with a > trivial patch. There's a big difference between "writable" and "might be written". > If we do not _WANT_ to make it writable, then we can simply add .data > and .bss to .broken. That is the correct thing to do. > Yes, all .rel* sections should be in .broken, I guess. You can toss an "void *x = &x;" into the vdso sources to verify that this setup makes that explode gracefully. > This was an attempt to discard .note.GNU-stack, which is what the > default linker script does, but it appears that all .note.GNU-stack > sections are zero-size, so this change does not make any difference. Indeed it does not. Thanks, Roland -- 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/