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

[Leif Lindholm]

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?

/
    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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