Re: [Qemu-devel] [PATCH v9 01/26] target-arm: extend async excp masking

[Peter Maydell <peter.maydell@linaro.org>]

On 5 November 2014 23:22, Greg Bellows <greg.bellows@linaro.org> wrote:
> This patch extends arm_excp_unmasked() to use lookup tables for determining
> whether IRQ and FIQ exceptions are masked.  The lookup tables are based on the
> ARMv8 and ARMv7 specification physical interrupt masking tables.
>
> If EL3 is using AArch64 IRQ/FIQ masking is ignored in all exception levels
> other than EL3 if SCR.{FIQ|IRQ} is set to 1 (routed to EL3).
>
> Signed-off-by: Greg Bellows <greg.bellows@linaro.org>
>
> ---
>
> v8 -> v9
> - Undo the use of tables for exception masking and instead go with simplified
>   logic based on the target EL lookup.
> - Remove the masking tables
>
> v7 -> v8
> - Add IRQ and FIQ exeception masking lookup tables.
> - Rewrite patch to use lookup tables for determining whether an excpetion is
>   masked or not.
>
> v5 -> v6
> - Globally change Aarch# to AArch#
> - Fixed comment termination
>
> v4 -> v5
> - Merge with v4 patch 10
> ---
>  target-arm/cpu.h | 79 +++++++++++++++++++++++++++++++++++++-------------------
>  1 file changed, 53 insertions(+), 26 deletions(-)
>
> diff --git a/target-arm/cpu.h b/target-arm/cpu.h
> index cb6ec5c..0ea8602 100644
> --- a/target-arm/cpu.h
> +++ b/target-arm/cpu.h
> @@ -1247,39 +1247,51 @@ static inline bool arm_excp_unmasked(CPUState *cs, unsigned int excp_idx)
>      CPUARMState *env = cs->env_ptr;
>      unsigned int cur_el = arm_current_el(env);
>      unsigned int target_el = arm_excp_target_el(cs, excp_idx);
> -    /* FIXME: Use actual secure state.  */
> -    bool secure = false;
> -    /* If in EL1/0, Physical IRQ routing to EL2 only happens from NS state.  */
> -    bool irq_can_hyp = !secure && cur_el < 2 && target_el == 2;
> -    /* ARMv7-M interrupt return works by loading a magic value
> -     * into the PC.  On real hardware the load causes the
> -     * return to occur.  The qemu implementation performs the
> -     * jump normally, then does the exception return when the
> -     * CPU tries to execute code at the magic address.
> -     * This will cause the magic PC value to be pushed to
> -     * the stack if an interrupt occurred at the wrong time.
> -     * We avoid this by disabling interrupts when
> -     * pc contains a magic address.

I did suggest you based this on the M profile patches;
you'll find this doesn't apply to current master I think.

thanks
-- PMM