From patchwork Wed Apr 22 09:55:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 227005 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 B03D9C55185 for ; Wed, 22 Apr 2020 11:03:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C1782076E for ; Wed, 22 Apr 2020 11:03:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587553415; bh=8YW+VL7Rvwrp7w43VNwJQAPZ6cUavhUrP+7m41VNnqg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=C1Zkqn8QjA4gJjESGWdubUH2aKSs/HWVtMkRqxDE+INiRqsAZxvIydagtlGXG8H1B B+tyruBQwwyKnpEXWdwO2iLp+wNZvJccA6pZAZYuZM45kWJgxvW7lmsoThr4BKfhlN udpB7+36C12M+bLxO7K0TLm/b9dKhWGI9c79mY0c= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726540AbgDVJ7w (ORCPT ); Wed, 22 Apr 2020 05:59:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:46590 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726503AbgDVJ7r (ORCPT ); Wed, 22 Apr 2020 05:59:47 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 003842077D; Wed, 22 Apr 2020 09:59:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587549587; bh=8YW+VL7Rvwrp7w43VNwJQAPZ6cUavhUrP+7m41VNnqg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xKACA+05Ds2j9K2sHXoJwMdaHDiVd8iScKSjPlqSXsT7ph5WqlzfQu9y2MIUEK6sz hekd06sthPqBVBAxmM2XmVkTdJtSxyDmeff0chXMuhisSycNh9hLiJYwcHozPsxGjD ropTI0DNvZU+pwp10NNOsflXWATRJE+Jz/zGSvlU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jan Engelhardt , "Rafael J. Wysocki" Subject: [PATCH 4.4 025/100] acpi/x86: ignore unspecified bit positions in the ACPI global lock field Date: Wed, 22 Apr 2020 11:55:55 +0200 Message-Id: <20200422095027.301714732@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200422095022.476101261@linuxfoundation.org> References: <20200422095022.476101261@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jan Engelhardt commit ecb9c790999fd6c5af0f44783bd0217f0b89ec2b upstream. The value in "new" is constructed from "old" such that all bits defined as reserved by the ACPI spec[1] are left untouched. But if those bits do not happen to be all zero, "new < 3" will not evaluate to true. The firmware of the laptop(s) Medion MD63490 / Akoya P15648 comes with garbage inside the "FACS" ACPI table. The starting value is old=0x4944454d, therefore new=0x4944454e, which is >= 3. Mask off the reserved bits. [1] https://uefi.org/sites/default/files/resources/ACPI_6_2.pdf Link: https://bugzilla.kernel.org/show_bug.cgi?id=206553 Cc: All applicable Signed-off-by: Jan Engelhardt Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/acpi/boot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/kernel/acpi/boot.c +++ b/arch/x86/kernel/acpi/boot.c @@ -1708,7 +1708,7 @@ int __acpi_acquire_global_lock(unsigned new = (((old & ~0x3) + 2) + ((old >> 1) & 0x1)); val = cmpxchg(lock, old, new); } while (unlikely (val != old)); - return (new < 3) ? -1 : 0; + return ((new & 0x3) < 3) ? -1 : 0; } int __acpi_release_global_lock(unsigned int *lock)