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=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,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 3874AC4321A for ; Tue, 11 Jun 2019 14:13:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1A3B520896 for ; Tue, 11 Jun 2019 14:13:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387551AbfFKON2 (ORCPT ); Tue, 11 Jun 2019 10:13:28 -0400 Received: from mx2.suse.de ([195.135.220.15]:44164 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2387447AbfFKON1 (ORCPT ); Tue, 11 Jun 2019 10:13:27 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C3F52AF1F; Tue, 11 Jun 2019 14:13:25 +0000 (UTC) From: Miroslav Benes To: jpoimboe@redhat.com, jikos@kernel.org, pmladek@suse.com Cc: joe.lawrence@redhat.com, kamalesh@linux.vnet.ibm.com, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, Miroslav Benes Subject: [PATCH v4 2/3] Revert "livepatch: Remove reliable stacktrace check in klp_try_switch_task()" Date: Tue, 11 Jun 2019 16:13:19 +0200 Message-Id: <20190611141320.25359-3-mbenes@suse.cz> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190611141320.25359-1-mbenes@suse.cz> References: <20190611141320.25359-1-mbenes@suse.cz> 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 reverts commit 1d98a69e5cef3aeb68bcefab0e67e342d6bb4dad. Commit 31adf2308f33 ("livepatch: Convert error about unsupported reliable stacktrace into a warning") weakened the enforcement for architectures to have reliable stack traces support. The system only warns now about it. It only makes sense to reintroduce the compile time checking in klp_try_switch_task() again and bail out early. Signed-off-by: Miroslav Benes --- kernel/livepatch/transition.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c index 8e8c79d4b204..7e7ef04689d1 100644 --- a/kernel/livepatch/transition.c +++ b/kernel/livepatch/transition.c @@ -293,6 +293,13 @@ static bool klp_try_switch_task(struct task_struct *task) if (task->patch_state == klp_target_state) return true; + /* + * For arches which don't have reliable stack traces, we have to rely + * on other methods (e.g., switching tasks at kernel exit). + */ + if (!klp_have_reliable_stack()) + return false; + /* * Now try to check the stack for any to-be-patched or to-be-unpatched * functions. If all goes well, switch the task to the target patch -- 2.21.0