[PATCH 0/3] Fix Thumb-2 undef handling for mixed-arch kernels

Dave Martin dave.martin at linaro.org
Tue Aug 16 12:06:52 EDT 2011


On Tue, Aug 16, 2011 at 3:58 PM, Tixy <tixy at yxit.co.uk> wrote:
> On Tue, 2011-08-16 at 15:14 +0100, Dave Martin wrote:
>> In kernels which support v6 and v7 platforms in a single binary
>> such as omap2plus_defconfig for example, undefined instruction
>> exceptions taken on Thumb instructions are not processed correctly,
>> because the kernel assumes at build-time that Thumb-2 won't be
>> supported in userspace.
>>
>> This series implements a workaround, by allowing the __und_usr
>> handler to check the CPU architecture at runtime, in affected
>> kernels.
>>
>> Changes since RFC:
>>   * Renamed the global variable to __cpu_architecture and provided
>>     cpu_architecture() as in inline function in <asm/system.h>.
>>     This brings back the old API, but more efficiently.
>>   * Dropped all the patches required to handle the reverted API
>>     change.
>>   * cpu_architecture is now declared __pure, which may lead to
>>     slightly more efficient code in some cases.
>>   * Added BUG_ON() to cpu_architecture() so that if
>>     __cpu_architecture is not set early enough, it gets noticed.
>>
>> Thanks to Tixy and Nicolas Pitre for their helpful feedback which
>> helped slim down this series.
>>
>> Dave Martin (3):
>>   ARM: Make cpu_alignment into a global variable
>>   ARM: entry: Remove unnecessary masking when decoding Thumb-2
>>     instructions
>>   ARM: entry: Fix Thumb-2 undef handling for multi-CPU kernels
>>
>>  arch/arm/include/asm/system.h |   11 +++++++++-
>>  arch/arm/kernel/entry-armv.S  |   44 ++++++++++++++++++++++++++++++++++++----
>>  arch/arm/kernel/setup.c       |    5 +++-
>>  3 files changed, 53 insertions(+), 7 deletions(-)
>>
>
> Looks good to me.

Thanks for looking over it.

Is that a Reviewed-by, or will you go for an Ack?

Cheers
---Dave



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