linux-kernel - Re: [PATCH v2 0/3] Correct for ACPI 5.1->6.0 spec changes in MADT GICC entries

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Message-ID: <5583F4F7.1000002@linaro.org>
Date:	Fri, 19 Jun 2015 18:54:47 +0800
From:	Hanjun Guo <hanjun.guo@...aro.org>
To:	Al Stone <al.stone@...aro.org>, linux-acpi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
CC:	rjw@...ysocki.net, lenb@...nel.org, catalin.marinas@....com,
	will.deacon@....com, tglx@...utronix.de, jason@...edaemon.net,
	linux-kernel@...r.kernel.org, linaro-acpi@...ts.linaro.org,
	linaro-kernel@...ts.linaro.org, patches@...aro.org
Subject: Re: [PATCH v2 0/3] Correct for ACPI 5.1->6.0 spec changes in MADT
 GICC entries

On 06/19/2015 06:36 AM, Al Stone wrote:
> In the ACPI 5.1 version of the spec, the struct for the GICC subtable
> (struct acpi_madt_generic_interrupt) of the MADT 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.
>
> Note that this was found in linux-next and these patches apply against
> that tree and the arm64 kernel tree; 4.1-rc8 does not appear to have this
> problem since it still has the 5.1 struct definition.
>
> Even though there is precendent in ia64 code for ignoring the changes in
> size, this patch set instead tries to verify correctness.  The first patch
> in the set adds macros for easily using the ACPI spec version.  The second
> patch adds the BAD_MADT_GICC_ENTRY() macro that uses the version macros to
> check the GICC subtable only, accounting for the difference in specification
> versions that are possible.  The final patch replaces BAD_MADT_ENTRY usage
> with the BAD_MADT_GICC_ENTRY macro in arm64 code, which is currently the
> only architecture affected.  The BAD_MADT_ENTRY() will continue to work as
> is for all other MADT subtables.
>
> I have tested these patches on an APM Mustang with version 1.15 firmware,
> where the problem was found, and they fix the problem.

I also tested on QEMU, it fixed the problem when I was using ACPICA 6.0
updates for MADT table,

Tested-by: Hanjun Guo <hanjun.guo@...aro.org>

Thanks
Hanjun

>
> Changes for v2:
>    -- Replace magic constants with proper defines (Lorenzo)
>    -- Minor syntax clean-up noted by checkpatch
>    -- Send out CCs properly this time
>    -- Minor clean-up of the paragraphs in this cover letter
>
>
> Al Stone (3):
>    ACPI : introduce macros for using the ACPI specification version
>    ACPI: add BAD_MADT_GICC_ENTRY() macro
>    ACPI / ARM64 : use the new BAD_MADT_GICC_ENTRY macro
>
>   arch/arm64/kernel/smp.c   |  2 +-
>   drivers/irqchip/irq-gic.c |  2 +-
>   include/linux/acpi.h      | 15 +++++++++++++++
>   3 files changed, 17 insertions(+), 2 deletions(-)
>
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