From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-13.4 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,T_DKIMWL_WL_MED,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 5D1D97DE78 for ; Thu, 30 Aug 2018 11:42:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728678AbeH3PnT (ORCPT ); Thu, 30 Aug 2018 11:43:19 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:40113 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728653AbeH3PnS (ORCPT ); Thu, 30 Aug 2018 11:43:18 -0400 Received: by mail-wm0-f66.google.com with SMTP id 207-v6so1659189wme.5 for ; Thu, 30 Aug 2018 04:41:35 -0700 (PDT) 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=W/jdbb2Vq3Kiym03/gav3BOUvcnL67E9+cfyfM7MhIU=; b=DMD4I/SS8lJ+d3U1+HP9Yl6kLLZHPhvAdJS/JxxXCHjmDxUF/UgLbg2LpoqOkcwLuR wQQPHq4FCtWNS5xr7a3yBgBLJiWBX59b39kyQUx1OqIRTZZTjyRpftdyJmGkxbABZFU6 5KDwphISdpfEXbTOa+4UH4EiTU/0Wi30p9H0GhSfdYr6ze+w3YzNJGGCjrGlYOzyxLmh iWSjewMZmvPQ1GwgRIhyGXsGTzAm8HlL91OxzULxqV+6QAR/5fdqnSyQQBmOZsTukWgi 9+fmCsSQzqxxTagM+2Wx2wT5yLGsY3A4DZXaZsUTAtgiarABDJqijOFj2slq5uuV7G9d s3yw== 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=W/jdbb2Vq3Kiym03/gav3BOUvcnL67E9+cfyfM7MhIU=; b=GUmm2zsuziAPr8MiELuEnxzjUtX5h7aGfsHGhD9vIaHCoEE9VGFekw/Q52BYXcJbT6 hTFti+K2W7X8s7r1piSu7JL304rmeG5RzpG+ZlYF4p9Sx7ppmH2kVi8rgrfhcUcLiZuo H/jFJP3B2gCbF7JpCnSvznK7sJKyX34zw4XAL4fRoZj0JjEfziwz3Mtz7vAWsah8CAcy EUZgDC578fPnvESM7G+m145B1oY4jXUify4BYjuC56wIfY9SkvrttoZKSHO5Qi2pLB7y PZxRM2lkjEyNHDEL3RV58RWM7VQlseNe0ZILWMu7c9B2jATdHn6xHJhqtUUlPCCV66Fg f5eQ== X-Gm-Message-State: APzg51CqxFWu2C6qAi8X4A6RIX95HreL9aGKdHL8nSesgQUgZNImrIX9 v+3qWzYZCNXpwDY3H7lO7QpqgA== X-Google-Smtp-Source: ANB0VdZJCY9SDGNv4X5vQQOPslJfwglBfynr1JnV8gKw4PAQtLtDlI07kC0OD66facMHWBf1VWf6KA== X-Received: by 2002:a1c:e54:: with SMTP id 81-v6mr1614151wmo.84.1535629293894; Thu, 30 Aug 2018 04:41:33 -0700 (PDT) Received: from andreyknvl0.muc.corp.google.com ([2a00:79e0:15:10:84be:a42a:826d:c530]) by smtp.gmail.com with ESMTPSA id z184-v6sm2175218wmz.0.2018.08.30.04.41.32 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 30 Aug 2018 04:41:33 -0700 (PDT) From: Andrey Konovalov To: Catalin Marinas , Will Deacon , Mark Rutland , Robin Murphy , Al Viro , Andrey Konovalov , 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 Subject: [PATCH v6 09/11] arm64: update Documentation/arm64/tagged-pointers.txt Date: Thu, 30 Aug 2018 13:41:14 +0200 Message-Id: <594756b2aa9fea948f4da3cd01ffa8a5acbc5805.1535629099.git.andreyknvl@google.com> X-Mailer: git-send-email 2.19.0.rc0.228.g281dcd1b4d0-goog In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Add a note that work on passing tagged user pointers to the kernel via syscalls has started, but might not be complete yet. Signed-off-by: Andrey Konovalov --- Documentation/arm64/tagged-pointers.txt | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/Documentation/arm64/tagged-pointers.txt b/Documentation/arm64/tagged-pointers.txt index a25a99e82bb1..361481283f00 100644 --- a/Documentation/arm64/tagged-pointers.txt +++ b/Documentation/arm64/tagged-pointers.txt @@ -35,8 +35,9 @@ 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 +Some initial work for supporting non-zero address tags passed to the +kernel via system calls has been done, but the kernel doesn't provide +any guarantees at this point. Using a non-zero address tag for sp is strongly discouraged. Programs maintaining a frame pointer and frame records that use non-zero -- 2.19.0.rc0.228.g281dcd1b4d0-goog