From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 307ECC43219 for ; Fri, 26 Apr 2019 15:33:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E4D81208CA for ; Fri, 26 Apr 2019 15:33:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="RJhkWf7s" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726974AbfDZPdT (ORCPT ); Fri, 26 Apr 2019 11:33:19 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:35164 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726188AbfDZPdS (ORCPT ); Fri, 26 Apr 2019 11:33:18 -0400 Received: by mail-pl1-f195.google.com with SMTP id w24so1757984plp.2; Fri, 26 Apr 2019 08:33:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=jhUgUnVwH131/xczA7BMawqjAt3u+4QIhEzyPGkH5gg=; b=RJhkWf7sm6bpcSYZUFM7l2vN1+aMdX6QBeCRKTZI5lWZL6wXxsmecJ2XICAWttvrnG 6BYdIGhmnV0CgNfO7g2zrAZT2ez2+dga6AujhU4eIp9R7CQfdE4KfCB3lsDpt6gY/yBZ nNcnQnNK0yJ5fJIpp1R3OcRQHZ68AHp9VYPUS+6bKn707UhS/tAvZtVGajE+TB/tK3rE 33rKJGih8MsUmp+Ivu7eNaP8KhTwS/BsgSfRiTBHnizuxBpWp01Imi1nOlpu/8o6w0qr jq5j4tOmzDCrKsF31HIo3daYv61o3ln0sf7nd+B08b776uvYCrHk+k2H54slC1U50GqM peUQ== 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=jhUgUnVwH131/xczA7BMawqjAt3u+4QIhEzyPGkH5gg=; b=YeAaHh5beRkRbjBAQ1ICCKxklj9YhcSw+thwsXzH2s2fpoaqsZcsK9vIPSYqXMwRHk 6TktS80ZPvAyHJrW968gWpjM/FlHRP6eEbd0g6j9ZhNxINW5898RJPIgXFvxx5ZpWCG4 k8zhoT7GirAN9C7wN8FB3af0dsmk0epYvsD7gKOoe9OX5XjiMUCVJ7NaU0sHDX710GIV GACe0r30DI+zKBfg55waclmHaUEd+ykqaz/88h0uCGjRkD4QKyEfDuwmFRnRzTRYQ5VD PptlP3w4ayxUf6w9rE5GGOcFW24lSE+03AVXLpB0oiZwFVGCHV78uBYJqPjE4RO6qCsk XIJA== X-Gm-Message-State: APjAAAWFyFSs+2ZgKbntQDxYyCjZW+OfIRQLDhzHiMZvyzABfb4WFchW 4eFsX4OE0vrw/V4qAsN+c3c= X-Google-Smtp-Source: APXvYqw+5MNiJwzvUyNuA4V9hTXMnyJGu6i+Nb+FqIeQP4dX5UtZYoGaeMY4TVdYMRwujv+cQmCGLQ== X-Received: by 2002:a17:902:28a9:: with SMTP id f38mr46042133plb.295.1556292797359; Fri, 26 Apr 2019 08:33:17 -0700 (PDT) Received: from localhost.localdomain ([104.238.181.70]) by smtp.gmail.com with ESMTPSA id b1sm29024833pgq.15.2019.04.26.08.33.12 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Apr 2019 08:33:16 -0700 (PDT) From: Changbin Du To: Jonathan Corbet Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, mchehab+samsung@kernel.org, Changbin Du Subject: [PATCH 12/27] Documentation: x86: convert protection-keys.txt to reST Date: Fri, 26 Apr 2019 23:31:35 +0800 Message-Id: <20190426153150.21228-13-changbin.du@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190426153150.21228-1-changbin.du@gmail.com> References: <20190426153150.21228-1-changbin.du@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This converts the plain text documentation to reStructuredText format and add it to Sphinx TOC tree. No essential content change. Signed-off-by: Changbin Du --- Documentation/x86/index.rst | 1 + ...rotection-keys.txt => protection-keys.rst} | 33 ++++++++++++------- 2 files changed, 22 insertions(+), 12 deletions(-) rename Documentation/x86/{protection-keys.txt => protection-keys.rst} (83%) diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst index e06b5c0ea883..576628b121cc 100644 --- a/Documentation/x86/index.rst +++ b/Documentation/x86/index.rst @@ -18,3 +18,4 @@ Linux x86 Support tlb mtrr pat + protection-keys diff --git a/Documentation/x86/protection-keys.txt b/Documentation/x86/protection-keys.rst similarity index 83% rename from Documentation/x86/protection-keys.txt rename to Documentation/x86/protection-keys.rst index ecb0d2dadfb7..49d9833af871 100644 --- a/Documentation/x86/protection-keys.txt +++ b/Documentation/x86/protection-keys.rst @@ -1,3 +1,9 @@ +.. SPDX-License-Identifier: GPL-2.0 + +====================== +Memory Protection Keys +====================== + Memory Protection Keys for Userspace (PKU aka PKEYs) is a feature which is found on Intel's Skylake "Scalable Processor" Server CPUs. It will be avalable in future non-server parts. @@ -23,9 +29,10 @@ even though there is theoretically space in the PAE PTEs. These permissions are enforced on data access only and have no effect on instruction fetches. -=========================== Syscalls =========================== +Syscalls +======== -There are 3 system calls which directly interact with pkeys: +There are 3 system calls which directly interact with pkeys:: int pkey_alloc(unsigned long flags, unsigned long init_access_rights) int pkey_free(int pkey); @@ -37,6 +44,7 @@ pkey_alloc(). An application calls the WRPKRU instruction directly in order to change access permissions to memory covered with a key. In this example WRPKRU is wrapped by a C function called pkey_set(). +:: int real_prot = PROT_READ|PROT_WRITE; pkey = pkey_alloc(0, PKEY_DISABLE_WRITE); @@ -45,43 +53,44 @@ called pkey_set(). ... application runs here Now, if the application needs to update the data at 'ptr', it can -gain access, do the update, then remove its write access: +gain access, do the update, then remove its write access:: pkey_set(pkey, 0); // clear PKEY_DISABLE_WRITE *ptr = foo; // assign something pkey_set(pkey, PKEY_DISABLE_WRITE); // set PKEY_DISABLE_WRITE again Now when it frees the memory, it will also free the pkey since it -is no longer in use: +is no longer in use:: munmap(ptr, PAGE_SIZE); pkey_free(pkey); -(Note: pkey_set() is a wrapper for the RDPKRU and WRPKRU instructions. - An example implementation can be found in - tools/testing/selftests/x86/protection_keys.c) +.. note:: pkey_set() is a wrapper for the RDPKRU and WRPKRU instructions. + An example implementation can be found in + tools/testing/selftests/x86/protection_keys.c. -=========================== Behavior =========================== +Behavior +======== The kernel attempts to make protection keys consistent with the -behavior of a plain mprotect(). For instance if you do this: +behavior of a plain mprotect(). For instance if you do this:: mprotect(ptr, size, PROT_NONE); something(ptr); -you can expect the same effects with protection keys when doing this: +you can expect the same effects with protection keys when doing this:: pkey = pkey_alloc(0, PKEY_DISABLE_WRITE | PKEY_DISABLE_READ); pkey_mprotect(ptr, size, PROT_READ|PROT_WRITE, pkey); something(ptr); That should be true whether something() is a direct access to 'ptr' -like: +like:: *ptr = foo; or when the kernel does the access on the application's behalf like -with a read(): +with a read():: read(fd, ptr, 1); -- 2.20.1