From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753228AbbIJQU1 (ORCPT ); Thu, 10 Sep 2015 12:20:27 -0400 Received: from foss.arm.com ([217.140.101.70]:34597 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752626AbbIJQUY (ORCPT ); Thu, 10 Sep 2015 12:20:24 -0400 Subject: Re: [PATCH v2 1/5] ACPI: add in a bad_madt_entry() function to eventually replace the macro To: Al Stone , Al Stone , "linux-acpi@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" References: <1440022048-6285-1-git-send-email-al.stone@linaro.org> <1440022048-6285-2-git-send-email-al.stone@linaro.org> <55EDADF5.5060008@arm.com> <55F08F47.1070906@redhat.com> Cc: Sudeep Holla , "linaro-kernel@lists.linaro.org" , "linux-ia64@vger.kernel.org" , "patches@linaro.org" , "linux-pm@vger.kernel.org" , "linaro-acpi@lists.linaro.org" , "Rafael J. Wysocki" , "linux-kernel@vger.kernel.org" , Len Brown From: Sudeep Holla Message-ID: <55F1ADC4.7090005@arm.com> Date: Thu, 10 Sep 2015 17:20:20 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <55F08F47.1070906@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/09/15 20:57, Al Stone wrote: > On 09/07/2015 09:32 AM, Sudeep Holla wrote: >> Hi Al, >> >> On 19/08/15 23:07, Al Stone wrote: >> >> I finally got a chance to try this series on Juno. Well it exposed a firmware >> bug in MADT table :) >> >> [..] >> >>> acpi_tbl_entry_handler handler, >>> @@ -245,6 +484,8 @@ acpi_parse_entries(char *id, unsigned long table_size, >>> table_end) { >>> if (entry->type == entry_id >>> && (!max_entries || count < max_entries)) { >>> + if (bad_madt_entry(table_header, entry)) >>> + return -EINVAL; >> >> Not sure if we can have the above check here unconditionally. >> Currently I can see there are 2 other users of acpi_parse_entries i.e. >> PCC and NUMA. So may be it can be made conditional or return success for >> non-MADT tables from bad_madt_entry ? > > So, I went back and double checked the other users and they're looking at > the return value for acpi_parse_entries properly; adding in the check above > unconditionally should not cause any behavior change. I disagree. I populated PCCT table on Juno to get this error for PCCT(PCCT header gets interpreted as MADT header): " ACPI: undefined version for either FADT 5.1 or MADT 1 Error parsing PCC subspaces from PCCT " And here the stacktrace: [] bad_madt_entry+0x90/0x16c [] acpi_table_parse_entries+0xfc/0x180 [] pcc_init+0x70/0x148 > Further, despite the name, acpi_parse_entries is only used to examine MADT > subtables. Granted, we should probably make the name clearer at some point > (too ambiguous as to which entries are parsed right now). Nonetheless, current > usage seems to be in order. > From the code inspection, I can see we have 3 users of acpi_parse_entries not just MADT but also PCC and NUMA/SRAT Something like this solves this issue: - if (bad_madt_entry(table_header, entry)) + if (!strncmp(id, ACPI_SIG_MADT, 4) && + bad_madt_entry(table_header, entry) Or am I still missing something ? Regards, Sudeep