On 8/14/18 2:42 PM, Peter Maydell wrote: > The MSR (banked) and MRS (banked) instructions allow accesses to ELR_Hyp > from either Monitor or Hyp mode. Our translate time check > was overly strict and only permitted access from Monitor mode. > > The runtime check wo do in msr_mrs_banked_exc_checks() had the "we" > correct code in it, but never got there because of the earlier > "currmode == tgtmode" check. Special case ELR_Hyp. > > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
Reviewed-By: Luc Michel <luc.mic...@greensocs.com>
> ---
> target/arm/op_helper.c | 22 +++++++++++-----------
> target/arm/translate.c | 10 +++++++---
> 2 files changed, 18 insertions(+), 14 deletions(-)
>
> diff --git a/target/arm/op_helper.c b/target/arm/op_helper.c
> index d550978b5b9..952b8d122b7 100644
> --- a/target/arm/op_helper.c
> +++ b/target/arm/op_helper.c
> @@ -611,6 +611,14 @@ static void msr_mrs_banked_exc_checks(CPUARMState *env,
> uint32_t tgtmode,
> */
> int curmode = env->uncached_cpsr & CPSR_M;
>
> + if (regno == 17) {
> + /* ELR_Hyp: a special case because access from tgtmode is OK */
> + if (curmode != ARM_CPU_MODE_HYP && curmode != ARM_CPU_MODE_MON) {
> + goto undef;
> + }
> + return;
> + }
> +
> if (curmode == tgtmode) {
> goto undef;
> }
> @@ -638,17 +646,9 @@ static void msr_mrs_banked_exc_checks(CPUARMState *env,
> uint32_t tgtmode,
> }
>
> if (tgtmode == ARM_CPU_MODE_HYP) {
> - switch (regno) {
> - case 17: /* ELR_Hyp */
> - if (curmode != ARM_CPU_MODE_HYP && curmode != ARM_CPU_MODE_MON) {
> - goto undef;
> - }
> - break;
> - default:
> - if (curmode != ARM_CPU_MODE_MON) {
> - goto undef;
> - }
> - break;
> + /* SPSR_Hyp, r13_hyp: accessible from Monitor mode only */
> + if (curmode != ARM_CPU_MODE_MON) {
> + goto undef;
> }
> }
>
> diff --git a/target/arm/translate.c b/target/arm/translate.c
> index f845da7c638..3f5751d4826 100644
> --- a/target/arm/translate.c
> +++ b/target/arm/translate.c
> @@ -4506,10 +4506,14 @@ static bool msr_banked_access_decode(DisasContext *s,
> int r, int sysm, int rn,
> }
> break;
> case ARM_CPU_MODE_HYP:
> - /* Note that we can forbid accesses from EL2 here because they
> - * must be from Hyp mode itself
> + /*
> + * SPSR_hyp and r13_hyp can only be accessed from Monitor mode
> + * (and so we can forbid accesses from EL2 or below). elr_hyp
> + * can be accessed also from Hyp mode, so forbid accesses from
> + * EL0 or EL1.
> */
> - if (!arm_dc_feature(s, ARM_FEATURE_EL2) || s->current_el < 3) {
> + if (!arm_dc_feature(s, ARM_FEATURE_EL2) || s->current_el < 2 ||
> + (s->current_el < 3 && *regno != 17)) {
> goto undef;
> }
> break;
>
signature.asc
Description: OpenPGP digital signature
