target/arm: Factor out "get mmuidx for specified security state"

For the SG instruction and secure function return we are going
to want to do memory accesses using the MMU index of the CPU
in secure state, even though the CPU is currently in non-secure
state. Write arm_v7m_mmu_idx_for_secstate() to do this job,
and use it in cpu_mmu_index().

Signed-off-by: Peter Maydell <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Message-id: [email protected]

target/arm/cpu.h

@@ -2329,23 +2329,33 @@ static inline int arm_mmu_idx_to_el(ARMMMUIdx mmu_idx)
     }
 }
 
+/* Return the MMU index for a v7M CPU in the specified security state */
+static inline ARMMMUIdx arm_v7m_mmu_idx_for_secstate(CPUARMState *env,
+                                                     bool secstate)
+{
+    int el = arm_current_el(env);
+    ARMMMUIdx mmu_idx;
+
+    if (el == 0) {
+        mmu_idx = secstate ? ARMMMUIdx_MSUser : ARMMMUIdx_MUser;
+    } else {
+        mmu_idx = secstate ? ARMMMUIdx_MSPriv : ARMMMUIdx_MPriv;
+    }
+
+    if (armv7m_nvic_neg_prio_requested(env->nvic, secstate)) {
+        mmu_idx = secstate ? ARMMMUIdx_MSNegPri : ARMMMUIdx_MNegPri;
+    }
+
+    return mmu_idx;
+}
+
 /* Determine the current mmu_idx to use for normal loads/stores */
 static inline int cpu_mmu_index(CPUARMState *env, bool ifetch)
 {
     int el = arm_current_el(env);
 
     if (arm_feature(env, ARM_FEATURE_M)) {
-        ARMMMUIdx mmu_idx;
-
-        if (el == 0) {
-            mmu_idx = env->v7m.secure ? ARMMMUIdx_MSUser : ARMMMUIdx_MUser;
-        } else {
-            mmu_idx = env->v7m.secure ? ARMMMUIdx_MSPriv : ARMMMUIdx_MPriv;
-        }
-
-        if (armv7m_nvic_neg_prio_requested(env->nvic, env->v7m.secure)) {
-            mmu_idx = env->v7m.secure ? ARMMMUIdx_MSNegPri : ARMMMUIdx_MNegPri;
-        }
+        ARMMMUIdx mmu_idx = arm_v7m_mmu_idx_for_secstate(env, env->v7m.secure);
 
         return arm_to_core_mmu_idx(mmu_idx);
     }