Re: [PATCH] grub-core/kern/arm/misc.S: fix unaligned grub_uint64_t local variable

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 25.11.2014 13:43, Leif Lindholm wrote:
> On Thu, Nov 20, 2014 at 09:53:14PM +0100, David Kozub wrote:
>> The unaligned local in __aeabi_uidivmod leads to a store to a 64bit
>> value at an address that is not divisible by 8 (in grub_divmod64).
>> The compiler most likely generates a STRD instruction to store it and
>> this causes an exception.
>>
>> Fixes Savannah bug #43632.
> 
> I agree with this patch - am I OK to push?
> 
Go ahead.
> /
>     Leif
>  
>> This includes improvements done by Leif Lindholm.
>> ---
>>  ChangeLog                 |  6 ++++++
>>  grub-core/kern/arm/misc.S | 14 +++++++-------
>>  2 files changed, 13 insertions(+), 7 deletions(-)
>>
>> diff --git a/ChangeLog b/ChangeLog
>> index 6fbec06..8728c04 100644
>> --- a/ChangeLog
>> +++ b/ChangeLog
>> @@ -1,3 +1,9 @@
>> +2014-11-21  David Kozub  <address@hidden>
>> +
>> +    * grub-core/kern/arm/misc.S: fix unaligned 64bit local variable
>> +    in __aeabi_uidivmod
>> +    Fixes Savannah bug #43632.
>> +
>>  2014-11-20  Andrei Borzenkov  <address@hidden>
>>  
>>      * tests/util/grub-fs-tester.in: Consistently print output
>> diff --git a/grub-core/kern/arm/misc.S b/grub-core/kern/arm/misc.S
>> index 8943cc3..16b6f8e 100644
>> --- a/grub-core/kern/arm/misc.S
>> +++ b/grub-core/kern/arm/misc.S
>> @@ -60,17 +60,17 @@ FUNCTION(__aeabi_lmul)
>>  
>>      .macro division parent
>>  
>> -        stmfd   sp!, {lr}
>> -        sub     sp, sp, #12
>> +        sub     sp, sp, #8      @ Allocate naturally aligned 64-bit space
>> +        stmfd   sp!, {r3,lr}    @ Dummy r3 to maintain stack alignment
>> +        add     r3, sp, #8      @ Set r3 to address of 64-bit space
>> +        str     r3, [sp]        @ Stack parameter, pointer to 64-bit space
>>          mov     r2, r1
>> -        add     r1, sp, #4
>> -        str     r1, [sp, #0]
>>          mov     r1, #0
>>          mov     r3, #0
>>          bl      \parent
>> -    ldr     r1, [sp, #4]
>> -        add     sp, sp, #12
>> -        ldmfd   sp!, {lr}
>> +        ldr     r1, [sp, #8]    @ Extract remainder
>> +        ldmfd   sp!, {r3,lr}    @ Pop into an unused arg/scratch register
>> +        add     sp, sp, #8
>>          bx      lr
>>      .endm
>>  
>> -- 
>> 2.1.1
>>
>>
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>> https://lists.gnu.org/mailman/listinfo/grub-devel
> 
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