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Re: [PATCH] grub-core/kern/arm/misc.S: fix unaligned grub_uint64_t local
From: |
Leif Lindholm |
Subject: |
Re: [PATCH] grub-core/kern/arm/misc.S: fix unaligned grub_uint64_t local variable |
Date: |
Tue, 25 Nov 2014 11:43:57 +0000 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
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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