From patchwork Thu Jan 4 13:58:40 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Richard Earnshaw \(lists\)" X-Patchwork-Id: 123422 Delivered-To: patch@linaro.org Received: by 10.140.22.227 with SMTP id 90csp11460553qgn; Thu, 4 Jan 2018 05:59:10 -0800 (PST) X-Google-Smtp-Source: ACJfBotsThhCPn/6vsrh52H8AJjzlhUtkOvncNqAY19hvzQq5BBT+3y8ILkhLrY0ddTtuGtfsUo2 X-Received: by 10.101.88.65 with SMTP id s1mr4075604pgr.366.1515074350771; Thu, 04 Jan 2018 05:59:10 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1515074350; cv=none; d=google.com; s=arc-20160816; b=xDkD3MOOHXaMAfGDLdLuouqdH7v1X6GXWfj4Ejy9PNVVEdTH8rpYyB7eKJ78HIbVcu sg1Rfvviyfv9tsKgAHCOqHOW4HT9pt9A5F7Rcnrs01kPFy2BQIBcVJuRzrDgEmwFWuRx UFslaq80Fq/HuaPHp1X/Wjojjuf4Ggndk4ybyaifA+skPL6j3uXYzoOLBRryfA33+cb1 MT9vVP6TDfE6Sj04rfdfRDrlEM5ob1u5+yZ14q/wLdwg+XtFtQ5DoWs30IPWnANT0Qpm shvncyzZPFXY9NuCK3euW3bVAcLFeyJvNAXgfzlmb0+/gzv/6WpgI/CkJioK6f0f9l52 dx8A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:message-id:date:subject:cc:to:from:delivered-to:sender :list-help:list-post:list-archive:list-unsubscribe:list-id :precedence:mailing-list:dkim-signature:domainkey-signature :arc-authentication-results; bh=NWg77fNrtI7rqOTt32hJp/8UYqkxH6e2wGuPBJ1UZEo=; b=UXfpK7xm3zJWXIIoGpetx6oWvAI5bdxqpQ5fGU7eKOow4awJucT3dySNNLSyh1C8/L zAkPXcR78Yc1THb3t0MSLnL7iU3z13DSq97ti4EUwcRQ1waUK/yqxwbYgj2llCZV5kWf xyTIC35uS0gBeB8qEWGP8U/O7vu1BS5e1FHFt/GHGXbf1iaypAtiKfIYyAWre2qpc5zm QMPdtHkDQo0oh8+Pbb9kFI4lHh3IrnDqiyaaGx7KA9EoJav5IkHnd4c3mgAReJ/Ysh++ vvw8Dpcm1qFG1tL0gpDoI5pt8QMKP+cZSfGiTMgmgO9jkXbus6fGVMGl45+/jduec2ds MHtw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gcc.gnu.org header.s=default header.b=ca2KyJT0; spf=pass (google.com: domain of gcc-patches-return-470134-patch=linaro.org@gcc.gnu.org designates 209.132.180.131 as permitted sender) smtp.mailfrom=gcc-patches-return-470134-patch=linaro.org@gcc.gnu.org Return-Path: Received: from sourceware.org (server1.sourceware.org. [209.132.180.131]) by mx.google.com with ESMTPS id m5si2071357pgc.767.2018.01.04.05.59.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Jan 2018 05:59:10 -0800 (PST) Received-SPF: pass (google.com: domain of gcc-patches-return-470134-patch=linaro.org@gcc.gnu.org designates 209.132.180.131 as permitted sender) client-ip=209.132.180.131; Authentication-Results: mx.google.com; dkim=pass header.i=@gcc.gnu.org header.s=default header.b=ca2KyJT0; spf=pass (google.com: domain of gcc-patches-return-470134-patch=linaro.org@gcc.gnu.org designates 209.132.180.131 as permitted sender) smtp.mailfrom=gcc-patches-return-470134-patch=linaro.org@gcc.gnu.org DomainKey-Signature: a=rsa-sha1; c=nofws; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender:from :to:cc:subject:date:message-id:mime-version:content-type; q=dns; s=default; b=NaJv9goGEg11IffcKbZl1NvrImCjy80cOKRC3vcxBWuDHu83Gb GRkZDbVlLMxVqYMby1shVByQmsnngnK2jhOM1iNbF4kQb9FLGSO+TBV9AEkPiHyf kC83aCL+xO/IhNtGSaNcR2Wf/Dh0j7EU6t/28fQ9ZIdPSxEMcM0zdCXBM= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender:from :to:cc:subject:date:message-id:mime-version:content-type; s= default; bh=b8aDUBNo5pHHYOr0y4D5AUyv0zI=; b=ca2KyJT0xN04YnKxwZDT 8sWhF3cQOLwxIAJo7EscHoaM6hT8459VzdiVmOHxr4xv5ysp1wFiJSHoqPuLAjDq TjmyIK+gLhDxIJUHcnBvuF9IF4rS41ZfVl9btIEPh66zh92l2ywVbDYnq3oOvTUi UFANzJScts+34+fmJiVw12w= Received: (qmail 87756 invoked by alias); 4 Jan 2018 13:58:57 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Delivered-To: mailing list gcc-patches@gcc.gnu.org Received: (qmail 87710 invoked by uid 89); 4 Jan 2018 13:58:57 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-5.4 required=5.0 tests=BAYES_00, GIT_PATCH_3, KAM_SHORT, SPF_PASS, T_RP_MATCHES_RCVD, URIBL_BLACK autolearn=ham version=3.3.2 spammy=UD:builtins.def, builtinsdef, builtins.def, c-cppbuiltin.c X-HELO: foss.arm.com Received: from usa-sjc-mx-foss1.foss.arm.com (HELO foss.arm.com) (217.140.101.70) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 04 Jan 2018 13:58:54 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 53AAA80D; Thu, 4 Jan 2018 05:58:52 -0800 (PST) Received: from e105689-lin.cambridge.arm.com (e105689-lin.cambridge.arm.com [10.2.207.32]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8A3333F581; Thu, 4 Jan 2018 05:58:51 -0800 (PST) From: Richard Earnshaw To: gcc-patches@gcc.gnu.org Cc: Richard Earnshaw Subject: [PATCH 0/3] Add __builtin_load_no_speculate Date: Thu, 4 Jan 2018 13:58:40 +0000 Message-Id: MIME-Version: 1.0 Recently, Google Project Zero disclosed several classes of attack against speculative execution. One of these, known as variant-1 (CVE-2017-5753), allows explicit bounds checks to be bypassed under speculation, providing an arbitrary read gadget. Further details can be found on the GPZ blog [1] and the documentation that is included with the first patch. This patch set adds a new builtin function for GCC to provide a mechanism for limiting speculation by a CPU after a bounds-checked memory access. I've tried to design this in such a way that it can be used for any target where this might be necessary. The patch set provides a generic implementation of the builtin and then target-specific support for Arm and AArch64. Other architectures can utilize the internal infrastructure as needed. Most of the details of the builtin and the hooks that need to be implemented to support it are described in the updates to the manual, but a short summary is given below. TYP __builtin_load_no_speculate (const volatile TYP *ptr, const volatile void *lower, const volatile void *upper, TYP failval, const volatile void *cmpptr) Where TYP can be any integral type (signed or unsigned char, int, short, long, etc) or any pointer type. The builtin implements the following logical behaviour: inline TYP __builtin_load_no_speculate (const volatile TYP *ptr, const volatile void *lower, const volatile void *upper, TYP failval, const volatile void *cmpptr) { TYP result; if (cmpptr >= lower && cmpptr < upper) result = *ptr; else result = failval; return result; } in addition the specification of the builtin ensures that future speculation using *ptr may only continue iff cmpptr lies within the bounds specified. Some optimizations are permitted to make the builtin easier to use. The final two arguments can both be omitted (c++ style): failval will default to 0 in this case and if cmpptr is omitted ptr will be used for expansions of the range check. In addition either lower or upper (but not both) may be a literal NULL and the expansion will then ignore that boundary condition when expanding. The patch set is constructed as follows: 1 - generic modifications to GCC providing the builtin function for all architectures and expanding to an implementation that gives the logical behaviour of the builtin only. A warning is generated if this expansion path is used that code will execute correctly but without providing protection against speculative use. 2 - AArch64 support 3 - AArch32 support (arm) for A32 and thumb2 states. These patches can be used with the header file that Arm recently published here: https://github.com/ARM-software/speculation-barrier. Kernel patches are also being developed, eg: https://lkml.org/lkml/2018/1/3/754. The intent is that eventually code like this will be able to use support directly from the compiler in a portable manner. Similar patches are also being developed for LLVM and will be posted to their development lists shortly. [1] More information on the topic can be found here: https://googleprojectzero.blogspot.co.uk/2018/01/reading-privileged-memory-with-side.html Arm specific information can be found here: https://www.arm.com/security-update Richard Earnshaw (3): [builtins] Generic support for __builtin_load_no_speculate() [aarch64] Implement support for __builtin_load_no_speculate. [arm] Implement support for the de-speculation intrinsic gcc/builtin-types.def | 16 +++++ gcc/builtins.c | 99 +++++++++++++++++++++++++ gcc/builtins.def | 22 ++++++ gcc/c-family/c-common.c | 164 ++++++++++++++++++++++++++++++++++++++++++ gcc/c-family/c-cppbuiltin.c | 5 +- gcc/config/aarch64/aarch64.c | 92 ++++++++++++++++++++++++ gcc/config/aarch64/aarch64.md | 28 ++++++++ gcc/config/arm/arm.c | 107 +++++++++++++++++++++++++++ gcc/config/arm/arm.md | 40 ++++++++++- gcc/config/arm/unspecs.md | 1 + gcc/doc/cpp.texi | 4 ++ gcc/doc/extend.texi | 53 ++++++++++++++ gcc/doc/tm.texi | 6 ++ gcc/doc/tm.texi.in | 2 + gcc/target.def | 20 ++++++ gcc/targhooks.c | 69 ++++++++++++++++++ gcc/targhooks.h | 3 + 17 files changed, 729 insertions(+), 2 deletions(-)