[PATCH] ARM: Allow kernel unaligned accesses on ARMv6+ processors

[John Linn]

> -----Original Message-----
> From: Catalin Marinas [mailto:catalin.marinas at gmail.com] On Behalf Of
> Catalin Marinas
> Sent: Saturday, November 05, 2011 3:41 AM
> To: linux-arm-kernel at lists.infradead.org
> Cc: John Linn
> Subject: [PATCH] ARM: Allow kernel unaligned accesses on ARMv6+
> processors
> 
> Recent gcc versions generate unaligned accesses by default on ARMv6
and
> later processors. This patch ensures that the SCTLR.A bit is always
> cleared on such processors to avoid kernel traping before
> alignment_init() is called.
> 
> Signed-off-by: Catalin Marinas <catalin.marinas at arm.com>
> Cc: John Linn <John.Linn at xilinx.com>

It worked great, thanks Catalin. I'd love to see a solution merged in
the mainline and this seems reasonable.
I'm being pushed to newer tools which require a solution.

Tested-by: John Linn <john.linn at xilinx.com>

> ---
>  arch/arm/kernel/head.S |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
> index a400a4d..1768db2 100644
> --- a/arch/arm/kernel/head.S
> +++ b/arch/arm/kernel/head.S
> @@ -394,7 +394,7 @@ __secondary_data:
>   *  r13 = *virtual* address to jump to upon completion
>   */
>  __enable_mmu:
> -#ifdef CONFIG_ALIGNMENT_TRAP
> +#if defined(CONFIG_ALIGNMENT_TRAP) && __LINUX_ARM_ARCH__ < 6
>  	orr	r0, r0, #CR_A
>  #else
>  	bic	r0, r0, #CR_A

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