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

[Andrei Borzenkov <arvidjaar@gmail.com>]

В Tue, 25 Nov 2014 11:43:57 +0000
Leif Lindholm <leif.lindholm@linaro.org> пишет:

> 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?

Yes, you are the best expert here.

> 
> /
>     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  <zub.272@gmail.com>
> > +
> > +	* grub-core/kern/arm/misc.S: fix unaligned 64bit local variable
> > +	in __aeabi_uidivmod
> > +	Fixes Savannah bug #43632.
> > +
> >  2014-11-20  Andrei Borzenkov  <arvidjaar@gmail.com>
> >  
> >  	* 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
> > 
> > 
> > _______________________________________________
> > Grub-devel mailing list
> > Grub-devel@gnu.org
> > https://lists.gnu.org/mailman/listinfo/grub-devel
> 
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