[U-Boot] [PATCH v4 2/2] arm: work around assembler bug

[Tom Rini <trini@ti.com>]

On 07/18/2012 11:06 PM, Albert ARIBAUD wrote:
> Hi Allen,
> 
> On Wed, 18 Jul 2012 16:45:53 -0700, Allen Martin <amartin@nvidia.com> wrote:
>> Disable sibling call optimization based on binutils version.  This is
>> to work around a bug in the assember in binutils versions < 2.22.
>> Branches to weak symbols can be incorrectly optimized in thumb mode to
>> a short branch (b.n instruction) that won't reach when the symbol gets
>> preempted.
>>
>> http://sourceware.org/bugzilla/show_bug.cgi?id=12532
>>
>> Signed-off-by: Allen Martin <amartin@nvidia.com>
>> ---
>> changes for v4:
>>  -removed warning print
>> changes for v3:
>>  -split shell line to improve readability
>> changes for v2:
>>  -changed GAS_BUG_12532 from yes/no to y/n to be consistent
>>  -added additional warning about code size increase
>> ---
>>  arch/arm/config.mk |   18 ++++++++++++++++++
>>  1 file changed, 18 insertions(+)
>>
>> diff --git a/arch/arm/config.mk b/arch/arm/config.mk
>> index 3f4453a..24b9d7c 100644
>> --- a/arch/arm/config.mk
>> +++ b/arch/arm/config.mk
>> @@ -87,3 +87,21 @@ endif
>>  ifndef CONFIG_NAND_SPL
>>  LDFLAGS_u-boot += -pie
>>  endif
>> +
>> +#
>> +# FIXME: binutils versions < 2.22 have a bug in the assembler where
>> +# branches to weak symbols can be incorrectly optimized in thumb mode
>> +# to a short branch (b.n instruction) that won't reach when the symbol
>> +# gets preempted
>> +#
>> +# http://sourceware.org/bugzilla/show_bug.cgi?id=12532
>> +#
>> +ifeq ($(CONFIG_SYS_THUMB_BUILD),y)
>> +ifeq ($(GAS_BUG_12532),)
>> +export GAS_BUG_12532:=$(shell if [ $(call binutils-version) -lt 0222 ] ; \
>> +	then echo y; else echo n; fi)
>> +endif
>> +ifeq ($(GAS_BUG_12532),y)
>> +PLATFORM_RELFLAGS += -fno-optimize-sibling-calls
>> +endif
>> +endif
> 
> Can previous reviewers ack or test this? I would like to have it in the ARM
> master branch in time for 12.07.

Acked-by: Tom Rini <trini@ti.com>

-- 
Tom