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=-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,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 DF8DEC5518C for ; Wed, 22 Apr 2020 10:04:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AEAF520774 for ; Wed, 22 Apr 2020 10:04:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587549844; bh=fJ96WCz+iWlr15uyMV2Md/i5n39XXHJodgUn1hJAodo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ot+4Z3Jl+n2mnwBSsnKeMZCoU1HArc2nI5c86CNBQ52thZms6B2/h8c5RvToz9XTR awCpmh7zWoBhucZGUTmumOuyiUzSMjE/eatBBD7MestK2K0MtKE2VxEUuhF+N5ts9y +tsLs+ylpLW0oKNmDbiwZWZzdywD/76TKUm7jQLQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727932AbgDVKED (ORCPT ); Wed, 22 Apr 2020 06:04:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:54114 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727918AbgDVKD7 (ORCPT ); Wed, 22 Apr 2020 06:03:59 -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 77D2A2076C; Wed, 22 Apr 2020 10:03:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587549838; bh=fJ96WCz+iWlr15uyMV2Md/i5n39XXHJodgUn1hJAodo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H/WAoO79fPOBCL+2DEdpEeJSxBAJRifQz105yab9DEC3KJBNIPL7wsGH2hFt8xrcQ IgXwX5KrZ3V0jXgFruKipu2aVPQoi0oSdAc2jYY6SaviJILIDXuP15HjrC3mQUgCwZ WSCGZ0z4oQWnsBI5qUzh7yfcBmET2iGXzwJsJnkE= 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 4.9 027/125] acpi/x86: ignore unspecified bit positions in the ACPI global lock field Date: Wed, 22 Apr 2020 11:55:44 +0200 Message-Id: <20200422095037.710919282@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200422095032.909124119@linuxfoundation.org> References: <20200422095032.909124119@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 @@ -1717,7 +1717,7 @@ 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)