On Thu, Feb 11, 2016 at 04:03:24PM +0000, Peter Maydell wrote:
> Correct some corner cases we were getting wrong for
> CNTFRQ access rights:
> * should UNDEF from 32-bit Secure EL1
> * only writable from the highest implemented exception level,
> which might not be EL1 now
>
> To clarify the code, provide a new utility function
> arm_highest_el() which returns the highest implemented
> exception level.
Reviewed-by: Edgar E. Iglesias <edgar.igles...@xilinx.com>
>
> Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
> ---
> Rewritten to use arm_highest_el() to improve clarity
> ---
> target-arm/cpu.h | 12 ++++++++++++
> target-arm/helper.c | 29 ++++++++++++++++++++++++++---
> 2 files changed, 38 insertions(+), 3 deletions(-)
>
> diff --git a/target-arm/cpu.h b/target-arm/cpu.h
> index 5137632..afbf366 100644
> --- a/target-arm/cpu.h
> +++ b/target-arm/cpu.h
> @@ -1255,6 +1255,18 @@ static inline bool cptype_valid(int cptype)
> #define PL1_RW (PL1_R | PL1_W)
> #define PL0_RW (PL0_R | PL0_W)
>
> +/* Return the highest implemented Exception Level */
> +static inline int arm_highest_el(CPUARMState *env)
> +{
> + if (arm_feature(env, ARM_FEATURE_EL3)) {
> + return 3;
> + }
> + if (arm_feature(env, ARM_FEATURE_EL2)) {
> + return 2;
> + }
> + return 1;
> +}
> +
> /* Return the current Exception Level (as per ARMv8; note that this differs
> * from the ARMv7 Privilege Level).
> */
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index 2f9db72..4d27c00 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -1218,10 +1218,33 @@ static const ARMCPRegInfo v6k_cp_reginfo[] = {
> static CPAccessResult gt_cntfrq_access(CPUARMState *env, const ARMCPRegInfo
> *ri,
> bool isread)
> {
> - /* CNTFRQ: not visible from PL0 if both PL0PCTEN and PL0VCTEN are zero */
> - if (arm_current_el(env) == 0 && !extract32(env->cp15.c14_cntkctl, 0, 2))
> {
> - return CP_ACCESS_TRAP;
> + /* CNTFRQ: not visible from PL0 if both PL0PCTEN and PL0VCTEN are zero.
> + * Writable only at the highest implemented exception level.
> + */
> + int el = arm_current_el(env);
> +
> + switch (el) {
> + case 0:
> + if (!extract32(env->cp15.c14_cntkctl, 0, 2)) {
> + return CP_ACCESS_TRAP;
> + }
> + break;
> + case 1:
> + if (!isread && ri->state == ARM_CP_STATE_AA32 &&
> + arm_is_secure_below_el3(env)) {
> + /* Accesses from 32-bit Secure EL1 UNDEF (*not* trap to EL3!) */
> + return CP_ACCESS_TRAP_UNCATEGORIZED;
> + }
> + break;
> + case 2:
> + case 3:
> + break;
> }
> +
> + if (!isread && el < arm_highest_el(env)) {
> + return CP_ACCESS_TRAP_UNCATEGORIZED;
> + }
> +
> return CP_ACCESS_OK;
> }
>
> --
> 1.9.1
>
