From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754497AbeEWHsW (ORCPT ); Wed, 23 May 2018 03:48:22 -0400 Received: from mx2.suse.de ([195.135.220.15]:56854 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754467AbeEWHr4 (ORCPT ); Wed, 23 May 2018 03:47:56 -0400 From: Petr Mladek To: Jiri Kosina , Josh Poimboeuf , Miroslav Benes Cc: Joe Lawrence , Jessica Yu , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, Petr Mladek Subject: [PATCH] livepatch: Remove not longer valid limitations from the documentation Date: Wed, 23 May 2018 09:47:42 +0200 Message-Id: <20180523074742.20171-1-pmladek@suse.com> X-Mailer: git-send-email 2.13.6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Semantic changes are possible since the commit d83a7cb375eec21f04 ("livepatch: change to a per-task consistency model"). Also data structures can be patched since the commit 439e7271dc2b63de37 ("livepatch: introduce shadow variable API"). It is a high time we removed these limitations from the documentation. Signed-off-by: Petr Mladek --- I have found this when working on v12 of the atomic replace. It looks like a no-brainer and does not conflict with the patchset, so ... ;-) Documentation/livepatch/livepatch.txt | 24 ------------------------ 1 file changed, 24 deletions(-) diff --git a/Documentation/livepatch/livepatch.txt b/Documentation/livepatch/livepatch.txt index 1ae2de758c08..2d7ed09dbd59 100644 --- a/Documentation/livepatch/livepatch.txt +++ b/Documentation/livepatch/livepatch.txt @@ -429,30 +429,6 @@ See Documentation/ABI/testing/sysfs-kernel-livepatch for more details. The current Livepatch implementation has several limitations: - - + The patch must not change the semantic of the patched functions. - - The current implementation guarantees only that either the old - or the new function is called. The functions are patched one - by one. It means that the patch must _not_ change the semantic - of the function. - - - + Data structures can not be patched. - - There is no support to version data structures or anyhow migrate - one structure into another. Also the simple consistency model does - not allow to switch more functions atomically. - - Once there is more complex consistency mode, it will be possible to - use some workarounds. For example, it will be possible to use a hole - for a new member because the data structure is aligned. Or it will - be possible to use an existing member for something else. - - There are no plans to add more generic support for modified structures - at the moment. - - + Only functions that can be traced could be patched. Livepatch is based on the dynamic ftrace. In particular, functions -- 2.13.6