From patchwork Thu Nov 8 14:36:14 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Konovalov X-Patchwork-Id: 10674369 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3E87614E2 for ; Thu, 8 Nov 2018 14:36:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2D70526C9B for ; Thu, 8 Nov 2018 14:36:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1DF6229C40; Thu, 8 Nov 2018 14:36:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, USER_IN_DEF_DKIM_WL autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AABCD26C9B for ; Thu, 8 Nov 2018 14:36:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727326AbeKIAMT (ORCPT ); Thu, 8 Nov 2018 19:12:19 -0500 Received: from mail-wr1-f67.google.com ([209.85.221.67]:46531 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727246AbeKIAMS (ORCPT ); Thu, 8 Nov 2018 19:12:18 -0500 Received: by mail-wr1-f67.google.com with SMTP id 74-v6so21475256wrb.13 for ; Thu, 08 Nov 2018 06:36:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=AfT6+8vP45oXrV17rGSZ9pzYS0my+RLSPjgVa2gqAd4=; b=UXht8r8Y+LVp07kCtfXSBeRBhpCaVOvYm1P+l9gMKK/QSvkAY4eFI/F/7dNdhFa+6s 03WsHwOPySnNl0C8RLlGZrgGNvf5upI9wpT2QD8fZu8QPcUo14dOOKGhsT3Vt3N2Xsfz jNCbI1daeAMYzEOF5k+/52Kcgvpjbbd1ZJorRlAFSppDB08ydUZoSHLoh0bXliV119yC tyWxnr6yN/1x8ngIwCnTTq6z3enqkxHT7u0Gob0KyEf1crq1MQb3JzblYwR/nihHzcHC ZK14++eId0uzOYOuwdG4frYt1cxu7q2wA7WvAPLwPwotre1YMk4rWNPG7CM0tgU1zuH6 v3bg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=AfT6+8vP45oXrV17rGSZ9pzYS0my+RLSPjgVa2gqAd4=; b=WfrOyBhVufrdLoAoJqXcJaAGtTy+vWdYG+81eXr7lH8tZOO9Bt/Gg2bI/ZAUEXZOqK uYSec5ZJuCitRMtZG+h6yZcBIiKZ/RFs3HRXyZqijylqD5lacT9t75Iyjjx7gSELCiGd wq/yGh/WDPE8SOdtnSu7NT+ahpggHJfyETJMkj9Bpt++QKw+tbb/VmOFlFYqc9GQiiXt 3SJSpKTaLQ1xqNZHM1ltEbr5v2ENondpj+WbZmz7U3xAMsyvHtidgbdqmPRh85iR2/bu BmD8Rr776GltfZ3xgqUIzGoSb1fOkpQHEvoW2ajyCGgNs3jpbYYqCg3c6V1vtQkGuyBf FYTQ== X-Gm-Message-State: AGRZ1gKlVG2goXAPVD5mitUc0Aia60aROr1bfReH+UCP+svOf/mqRnVD IVuvZAdK2zvywhK4oyWCHci7tw== X-Google-Smtp-Source: AJdET5cd+Vxy+CiHtQ9mm6FtFF35wdB6lNLfr2BV8z1ME65fDt3kZ6JEKazzaGEHLM0pA02L2pbaZA== X-Received: by 2002:a05:6000:1182:: with SMTP id g2mr4510493wrx.310.1541687790933; Thu, 08 Nov 2018 06:36:30 -0800 (PST) Received: from andreyknvl0.muc.corp.google.com ([2a00:79e0:15:10:84be:a42a:826d:c530]) by smtp.gmail.com with ESMTPSA id k5-v6sm5421068wre.82.2018.11.08.06.36.29 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 08 Nov 2018 06:36:30 -0800 (PST) From: Andrey Konovalov To: Catalin Marinas , Will Deacon , Mark Rutland , Robin Murphy , Kees Cook , Kate Stewart , Greg Kroah-Hartman , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Shuah Khan , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Chintan Pandya , Luc Van Oostenryck , Andrey Konovalov Subject: [PATCH v8 7/8] arm64: update Documentation/arm64/tagged-pointers.txt Date: Thu, 8 Nov 2018 15:36:14 +0100 Message-Id: <8526edb07fd5a762847306bba89fbadbb19210b7.1541687720.git.andreyknvl@google.com> X-Mailer: git-send-email 2.19.1.930.g4563a0d9d0-goog In-Reply-To: References: MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Document the changes in Documentation/arm64/tagged-pointers.txt. Signed-off-by: Andrey Konovalov --- Documentation/arm64/tagged-pointers.txt | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/Documentation/arm64/tagged-pointers.txt b/Documentation/arm64/tagged-pointers.txt index a25a99e82bb1..f4cf1f5cf362 100644 --- a/Documentation/arm64/tagged-pointers.txt +++ b/Documentation/arm64/tagged-pointers.txt @@ -17,13 +17,22 @@ this byte for application use. Passing tagged addresses to the kernel -------------------------------------- -All interpretation of userspace memory addresses by the kernel assumes -an address tag of 0x00. +The kernel supports tags in pointer arguments (including pointers in +structures) for a limited set of syscalls, the exceptions are: -This includes, but is not limited to, addresses found in: + - memory syscalls: brk, madvise, mbind, mincore, mlock, mlock2, move_pages, + mprotect, mremap, msync, munlock, munmap, pkey_mprotect, process_vm_readv, + process_vm_writev, remap_file_pages; - - pointer arguments to system calls, including pointers in structures - passed to system calls, + - ioctls that accept user pointers that describe virtual memory ranges; + + - TCP_ZEROCOPY_RECEIVE setsockopt. + +The kernel supports tags in user fault addresses. However the fault_address +field in the sigcontext struct will contain an untagged address. + +All other interpretations of userspace memory addresses by the kernel +assume an address tag of 0x00, in particular: - the stack pointer (sp), e.g. when interpreting it to deliver a signal, @@ -33,11 +42,7 @@ This includes, but is not limited to, addresses found in: Using non-zero address tags in any of these locations may result in an error code being returned, a (fatal) signal being raised, or other modes -of failure. - -For these reasons, passing non-zero address tags to the kernel via -system calls is forbidden, and using a non-zero address tag for sp is -strongly discouraged. +of failure. Using a non-zero address tag for sp is strongly discouraged. Programs maintaining a frame pointer and frame records that use non-zero address tags may suffer impaired or inaccurate debug and profiling