From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 24010 invoked by alias); 4 Dec 2018 03:51:10 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 23999 invoked by uid 89); 4 Dec 2018 03:51:09 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 spammy= X-HELO: EUR03-DB5-obe.outbound.protection.outlook.com Received: from mail-eopbgr40066.outbound.protection.outlook.com (HELO EUR03-DB5-obe.outbound.protection.outlook.com) (40.107.4.66) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 04 Dec 2018 03:51:07 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=armh.onmicrosoft.com; s=selector1-arm-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=tX2dKtXmUnKIAaEsELIpa8Cp/3trNTp52Mr67rzcHJY=; b=FTYkVGCBsxWKmQskqKpUoccasGnBbUmcACoH2YvTBic/DsGzTgExEybF81KN85Delr8QwkYGDGwxij7ZI+1LN5is/v/EeCN/06/GqnK6fFeyIvTP+p5dBJibWXKZlmpQK3PElunSOzDMmHYOiKXcD2W2EmQnYJIoHG/fZp+Thmk= Received: from HE1PR08MB1035.eurprd08.prod.outlook.com (10.166.125.145) by HE1PR08MB1034.eurprd08.prod.outlook.com (10.166.125.144) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1382.22; Tue, 4 Dec 2018 03:51:03 +0000 Received: from HE1PR08MB1035.eurprd08.prod.outlook.com ([fe80::f972:2c5d:c57c:7537]) by HE1PR08MB1035.eurprd08.prod.outlook.com ([fe80::f972:2c5d:c57c:7537%2]) with mapi id 15.20.1382.020; Tue, 4 Dec 2018 03:51:02 +0000 From: Wilco Dijkstra To: Florian Weimer , GCC Patches CC: nd Subject: Re: [RFC][AArch64] Add support for system register based stack protector canary access Date: Tue, 04 Dec 2018 03:51:00 -0000 Message-ID: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Wilco.Dijkstra@arm.com; received-spf: None (protection.outlook.com: arm.com does not designate permitted sender hosts) Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-SW-Source: 2018-12/txt/msg00145.txt.bz2 Hi, Florian wrote: > For userland, I would like to eventually copy the OpenBSD approach for > architectures which have some form of PC-relative addressing: we can > have multiple random canaries in (RELRO) .rodata in sufficiently close > to the code that needs them (assuming that we have split .rodata). At > least for x86-64, I expect this to be a small win. It's also a slight > hardening improvement if the reference canary is not stored in writable > memory. On AArch64 hardware pointer signing already provides a free and more robust implementation of stack canaries, so we could change -fstack-protector to use that when pointer signing is enabled. Wilco