target/arm: Diagnose incorrect usage of arm_is_secure subroutines

In several places we use arm_is_secure_below_el3 and
arm_is_el3_or_mon separately from arm_is_secure.
These functions make no sense for m-profile, and
would indicate prior incorrect feature testing.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230227225832.816605-4-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/cpu.h

@@ -2384,14 +2384,16 @@ static inline int arm_feature(CPUARMState *env, int feature)
 void arm_cpu_finalize_features(ARMCPU *cpu, Error **errp);
 
 #if !defined(CONFIG_USER_ONLY)
-/* Return true if exception levels below EL3 are in secure state,
+/*
+ * Return true if exception levels below EL3 are in secure state,
  * or would be following an exception return to that level.
  * Unlike arm_is_secure() (which is always a question about the
  * _current_ state of the CPU) this doesn't care about the current
  * EL or mode.
  */
 static inline bool arm_is_secure_below_el3(CPUARMState *env)
 {
+    assert(!arm_feature(env, ARM_FEATURE_M));
     if (arm_feature(env, ARM_FEATURE_EL3)) {
         return !(env->cp15.scr_el3 & SCR_NS);
     } else {
@@ -2405,6 +2407,7 @@ static inline bool arm_is_secure_below_el3(CPUARMState *env)
 /* Return true if the CPU is AArch64 EL3 or AArch32 Mon */
 static inline bool arm_is_el3_or_mon(CPUARMState *env)
 {
+    assert(!arm_feature(env, ARM_FEATURE_M));
     if (arm_feature(env, ARM_FEATURE_EL3)) {
         if (is_a64(env) && extract32(env->pstate, 2, 2) == 3) {
             /* CPU currently in AArch64 state and EL3 */