Re: [Qemu-arm] [Qemu-devel] [PATCH 03/20] target/arm: Prepare for CONTROL.SPSEL being nonzero in Handler mode

[Richard Henderson]

On 09/22/2017 10:59 AM, Peter Maydell wrote:
> In the v7M architecture, there is an invariant that if the CPU is
> in Handler mode then the CONTROL.SPSEL bit cannot be nonzero.
> This in turn means that the current stack pointer is always
> indicated by CONTROL.SPSEL, even though Handler mode always uses
> the Main stack pointer.
> 
> In v8M, this invariant is removed, and CONTROL.SPSEL may now
> be nonzero in Handler mode (though Handler mode still always
> uses the Main stack pointer). In preparation for this change,
> change how we handle this bit: rename switch_v7m_sp() to
> the now more accurate write_v7m_control_spsel(), and make it
> check both the handler mode state and the SPSEL bit.
> 
> Note that this implicitly changes the point at which we switch
> active SP on exception exit from before we pop the exception
> frame to after it.
> 
> Signed-off-by: Peter Maydell <address@hidden>
> ---
>  target/arm/cpu.h      |  8 ++++++-
>  hw/intc/armv7m_nvic.c |  2 +-
>  target/arm/helper.c   | 65 
> ++++++++++++++++++++++++++++++++++-----------------
>  3 files changed, 51 insertions(+), 24 deletions(-)

Reviewed-by: Richard Henderson <address@hidden>


r~