Re: [Qemu-devel] [Qemu-arm] [PATCH 1/7] target/arm: Handle SPSEL and current stack being out of sync in MSP/PSP reads

[Philippe Mathieu-Daudé]

On 12/01/2017 03:44 PM, Peter Maydell wrote:
> For v8M it is possible for the CONTROL.SPSEL bit value and the
> current stack to be out of sync. This means we need to update
> the checks used in reads and writes of the PSP and MSP special
> registers to use v7m_using_psp() rather than directly checking
> the SPSEL bit in the control register.

good catch.

> 
> Signed-off-by: Peter Maydell <address@hidden>

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

> ---
>  target/arm/helper.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index 91a9300..88394d4 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -9953,11 +9953,9 @@ uint32_t HELPER(v7m_mrs)(CPUARMState *env, uint32_t 
> reg)
>  
>      switch (reg) {
>      case 8: /* MSP */
> -        return (env->v7m.control[env->v7m.secure] & 
> R_V7M_CONTROL_SPSEL_MASK) ?
> -            env->v7m.other_sp : env->regs[13];
> +        return v7m_using_psp(env) ? env->v7m.other_sp : env->regs[13];
>      case 9: /* PSP */
> -        return (env->v7m.control[env->v7m.secure] & 
> R_V7M_CONTROL_SPSEL_MASK) ?
> -            env->regs[13] : env->v7m.other_sp;
> +        return v7m_using_psp(env) ? env->regs[13] : env->v7m.other_sp;
>      case 16: /* PRIMASK */
>          return env->v7m.primask[env->v7m.secure];
>      case 17: /* BASEPRI */
> @@ -10059,14 +10057,14 @@ void HELPER(v7m_msr)(CPUARMState *env, uint32_t 
> maskreg, uint32_t val)
>          }
>          break;
>      case 8: /* MSP */
> -        if (env->v7m.control[env->v7m.secure] & R_V7M_CONTROL_SPSEL_MASK) {
> +        if (v7m_using_psp(env)) {
>              env->v7m.other_sp = val;
>          } else {
>              env->regs[13] = val;
>          }
>          break;
>      case 9: /* PSP */
> -        if (env->v7m.control[env->v7m.secure] & R_V7M_CONTROL_SPSEL_MASK) {
> +        if (v7m_using_psp(env)) {
>              env->regs[13] = val;
>          } else {
>              env->v7m.other_sp = val;
>