Re: [Qemu-devel] [PATCH 5/8] target-arm: Fix wrong AArch64 entry offset for EL2/EL3 target

From: Sergey Fedorov <serge.fdrv@gmail.com>
To: Peter Maydell <peter.maydell@linaro.org>, qemu-devel@nongnu.org
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
	qemu-arm@nongnu.org, "Alex Bennée" <alex.bennee@linaro.org>,
	patches@linaro.org,
	"Edgar E. Iglesias" <edgar.iglesias@gmail.com>
Subject: Re: [Qemu-devel] [PATCH 5/8] target-arm: Fix wrong AArch64 entry offset for EL2/EL3 target
Date: Fri, 29 Jan 2016 19:47:14 +0300	[thread overview]
Message-ID: <56AB9792.8080302@gmail.com> (raw)
In-Reply-To: <1452796451-2946-6-git-send-email-peter.maydell@linaro.org>

On 14.01.2016 21:34, Peter Maydell wrote:
> The entry offset when taking an exception to AArch64 from a lower
> exception level may be 0x400 or 0x600. 0x400 is used if the
> implemented exception level immediately lower than the target level
> is using AArch64, and 0x600 if it is using AArch32. We were
> incorrectly implementing this as checking the exception level
> that the exception was taken from. (The two can be different if
> for example we take an exception from EL0 to AArch64 EL3; we should
> in this case be checking EL2 if EL2 is implemented, and EL1 if
> EL2 is not implemented.)

Reviewed-by: Sergey Fedorov <serge.fdrv@gmail.com>

> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  target-arm/helper.c | 21 ++++++++++++++++++++-
>  1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index d37c82c..196c111 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -5866,7 +5866,26 @@ static void arm_cpu_do_interrupt_aarch64(CPUState *cs)
>      unsigned int new_mode = aarch64_pstate_mode(new_el, true);
>  
>      if (arm_current_el(env) < new_el) {
> -        if (env->aarch64) {
> +        /* Entry vector offset depends on whether the implemented EL
> +         * immediately lower than the target level is using AArch32 or AArch64
> +         */
> +        bool is_aa64;
> +
> +        switch (new_el) {
> +        case 3:
> +            is_aa64 = (env->cp15.scr_el3 & SCR_RW) != 0;
> +            break;
> +        case 2:
> +            is_aa64 = (env->cp15.hcr_el2 & HCR_RW) != 0;
> +            break;
> +        case 1:
> +            is_aa64 = is_a64(env);
> +            break;
> +        default:
> +            g_assert_not_reached();
> +        }
> +
> +        if (is_aa64) {
>              addr += 0x400;
>          } else {
>              addr += 0x600;