[RFC PATCH 2/3] ARM: iwmmxt: Port problematic iwmmxt support code to v7/Thumb-2

[Eric Miao]

On Wed, Sep 7, 2011 at 8:59 AM, Dave Martin <dave.martin at linaro.org> wrote:
> The iwmmxt code contains some code to implement a pseudo-ISB, but
> this is not buildable for Thumb-2.
>
> This patch replaces the pseudo-ISB with a real one for Thumb-2
> kernels.
>
> Signed-off-by: Dave Martin <dave.martin at linaro.org>
> ---
>  arch/arm/kernel/iwmmxt.S |    9 +++++++++
>  1 files changed, 9 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/kernel/iwmmxt.S b/arch/arm/kernel/iwmmxt.S
> index a087838..bee8a74 100644
> --- a/arch/arm/kernel/iwmmxt.S
> +++ b/arch/arm/kernel/iwmmxt.S
> @@ -319,8 +319,17 @@ ENTRY(iwmmxt_task_switch)
>        PJ4(eor r1, r1, #0xf)
>        PJ4(mcr p15, 0, r1, c1, c0, 2)
>
> +/*
> + * When enough people have binutils which support -march=...+iwmmxt, this
> + * should change to #if __LINUX_ARM_ARCH__ < 7.
> + */
> +#ifndef CONFIG_THUMB2_KERNEL
>        mrc     p15, 0, r1, c2, c0, 0
>        sub     pc, lr, r1, lsr #32             @ cpwait and return
> +#else
> +       isb                                     @ ISB needed instead on ARMv7
> +       mov     pc, lr
> +#endif

Or maybe using ARM() and THUMB() will be a better fit here?