Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754738AbcJEIkX (ORCPT ); Wed, 5 Oct 2016 04:40:23 -0400 Received: from terminus.zytor.com ([198.137.202.10]:41464 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753129AbcJEIkV (ORCPT ); Wed, 5 Oct 2016 04:40:21 -0400 Date: Wed, 5 Oct 2016 01:39:59 -0700 From: tip-bot for Dave Hansen Message-ID: Cc: dave.hansen@intel.com, dave@sr71.net, mingo@kernel.org, hpa@zytor.com, tglx@linutronix.de, linux-kernel@vger.kernel.org Reply-To: tglx@linutronix.de, linux-kernel@vger.kernel.org, dave@sr71.net, mingo@kernel.org, dave.hansen@intel.com, hpa@zytor.com In-Reply-To: <20161004163857.71E0D6F6@viggo.jf.intel.com> References: <20161004163857.71E0D6F6@viggo.jf.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:mm/pkeys] x86/pkeys: Update documentation Git-Commit-ID: 6679dac513fd612f34d3a3d99d7b84ed6d5eb5cc X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2604 Lines: 63 Commit-ID: 6679dac513fd612f34d3a3d99d7b84ed6d5eb5cc Gitweb: http://git.kernel.org/tip/6679dac513fd612f34d3a3d99d7b84ed6d5eb5cc Author: Dave Hansen AuthorDate: Tue, 4 Oct 2016 09:38:57 -0700 Committer: Thomas Gleixner CommitDate: Wed, 5 Oct 2016 10:34:55 +0200 x86/pkeys: Update documentation There are a few items that have gotten stale in the protection keys documentation. The config option description only applied to the execute-only support and is not accurate for the current code. There was also a typo with the number of system calls. I also wanted to call out that pkey_set() is not a kernel-provided facility, and where to find an implementation. Signed-off-by: Dave Hansen Cc: Dave Hansen Cc: linux-doc@vger.kernel.org Cc: corbet@lwn.net Link: http://lkml.kernel.org/r/20161004163857.71E0D6F6@viggo.jf.intel.com Signed-off-by: Thomas Gleixner --- Documentation/x86/protection-keys.txt | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/Documentation/x86/protection-keys.txt b/Documentation/x86/protection-keys.txt index 6da7689..b643045 100644 --- a/Documentation/x86/protection-keys.txt +++ b/Documentation/x86/protection-keys.txt @@ -20,7 +20,7 @@ instruction fetches. =========================== Syscalls =========================== -There are 2 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); @@ -52,6 +52,10 @@ 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) + =========================== Behavior =========================== The kernel attempts to make protection keys consistent with the @@ -79,11 +83,3 @@ with a read(): The kernel will send a SIGSEGV in both cases, but si_code will be set to SEGV_PKERR when violating protection keys versus SEGV_ACCERR when the plain mprotect() permissions are violated. - -=========================== Config Option =========================== - -This config option adds approximately 1.5kb of text. and 50 bytes of -data to the executable. A workload which does large O_DIRECT reads -of holes in XFS files was run to exercise get_user_pages_fast(). No -performance delta was observed with the config option -enabled or disabled.