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Re: [Qemu-devel] [PATCH 2/7] target/arm: Allow explicit writes to CONTRO


From: Richard Henderson
Subject: Re: [Qemu-devel] [PATCH 2/7] target/arm: Allow explicit writes to CONTROL.SPSEL in Handler mode
Date: Sun, 3 Dec 2017 07:03:46 -0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0

On 12/01/2017 10:44 AM, Peter Maydell wrote:
> In ARMv7M the CPU ignores explicit writes to CONTROL.SPSEL
> in Handler mode. In v8M the behaviour is slightly different:
> writes to the bit are permitted but will have no effect.
> 
> We've already done the hard work to handle the value in
> CONTROL.SPSEL being out of sync with what stack pointer is
> actually in use, so all we need to do to fix this last loose
> end is to update the condition we use to guard whether we
> call write_v7m_control_spsel() on the register write.
> 
> Signed-off-by: Peter Maydell <address@hidden>
> ---
>  target/arm/helper.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

Reviewed-by: Richard Henderson <address@hidden>


r~



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