Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755519AbbFLOwk (ORCPT ); Fri, 12 Jun 2015 10:52:40 -0400 Received: from foss.arm.com ([217.140.101.70]:58816 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755155AbbFLOwc (ORCPT ); Fri, 12 Jun 2015 10:52:32 -0400 Date: Fri, 12 Jun 2015 15:52:44 +0100 From: Lorenzo Pieralisi To: "al.stone@linaro.org" Cc: "linux-acpi@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linaro-acpi@lists.linaro.org" , "patches@linaro.org" , "linaro-kernel@lists.linaro.org" Subject: Re: [PATCH 2/3] ACPI: add BAD_MADT_GICC_ENTRY() macro Message-ID: <20150612145244.GB27385@red-moon> References: <1434051911-14665-1-git-send-email-al.stone@linaro.org> <1434051911-14665-3-git-send-email-al.stone@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1434051911-14665-3-git-send-email-al.stone@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3114 Lines: 75 On Thu, Jun 11, 2015 at 08:45:10PM +0100, al.stone@linaro.org wrote: > From: Al Stone > > The BAD_MADT_ENTRY() macro is designed to work for all of the subtables > of the MADT. In the ACPI 5.1 version of the spec, the struct for the > GICC subtable (struct acpi_madt_generic_interrupt) is 76 bytes long; in > ACPI 6.0, the struct is 80 bytes long. But, there is only one definition > in ACPICA for this struct -- and that is the 6.0 version. Hence, when > BAD_MADT_ENTRY() compares the struct size to the length in the GICC > subtable, it fails if 5.1 structs are in use, and there are systems in > the wild that have them. > > This patch adds the BAD_MADT_GICC_ENTRY() that checks the GICC subtable > only, accounting for the difference in specification versions that are > possible. The BAD_MADT_ENTRY() will continue to work as is for all other > MADT subtables. Unfortunately that's nothing new, it seems. ia64 put in place a quite nifty solution to that (I *guess* owing to ACPI 3.0 updates to Local sapic specs), have a look at: arch/ia64/kernel/acpi.c acpi_parse_lsacpi() /*Skip BAD_MADT_ENTRY check, as lsapic size could vary */ We remove the check, job done ;-) > Signed-off-by: Al Stone > Reviewed-by: Hanjun Guo > Reviewed-by: Graeme Gregory > > CC: Rafael J. Wysocki > CC: Len Brown > > --- > include/linux/acpi.h | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index 33ed313..8a83f91 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -127,6 +127,13 @@ static inline void acpi_initrd_override(void *data, size_t size) > (!entry) || (unsigned long)entry + sizeof(*entry) > end || \ > ((struct acpi_subtable_header *)entry)->length < sizeof(*entry)) > > +#define BAD_MADT_GICC_ENTRY(entry, end) ( \ > + (!entry) || (unsigned long)entry + sizeof(*entry) > end || \ > + ((ACPI_FADT_SPEC_VERSION == ACPI_SPEC_VERSION(5,1)) && \ > + (entry->header.length != 76)) || \ > + ((ACPI_FADT_SPEC_VERSION == ACPI_SPEC_VERSION(6,0)) && \ > + (entry->header.length != 80))) I would make those length magic numbers ACPICA defines at least. It is not a GICC only issue, that's true for all MADT subtables that change size with versions so, maybe we can replace the sizeof(*entry) in BAD_MADT_ENTRY with a macro compound statement returning the subtable length (where you can add a switch case on entry->type and return sizeof(*entry) in the default case) ? Overkill ? Certainly ugly, but at least you do not need to patch anything else. I am inclined to relegate these checks to ACPICA tools (statically) altogether. It is better to check Len and Rafael opinion on this first before coding it. Lorenzo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/