target/arm: Introduce ARMSecuritySpace

Introduce both the enumeration and functions to retrieve
the current state, and state outside of EL3.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230620124418.805717-6-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 60 insertions, 0 deletions

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 006447dde8..f68923d73b 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -12136,3 +12136,63 @@ void aarch64_sve_change_el(CPUARMState *env, int old_el,
     }
 }
 #endif
+
+#ifndef CONFIG_USER_ONLY
+ARMSecuritySpace arm_security_space(CPUARMState *env)
+{
+    if (arm_feature(env, ARM_FEATURE_M)) {
+        return arm_secure_to_space(env->v7m.secure);
+    }
+
+    /*
+     * If EL3 is not supported then the secure state is implementation
+     * defined, in which case QEMU defaults to non-secure.
+     */
+    if (!arm_feature(env, ARM_FEATURE_EL3)) {
+        return ARMSS_NonSecure;
+    }
+
+    /* Check for AArch64 EL3 or AArch32 Mon. */
+    if (is_a64(env)) {
+        if (extract32(env->pstate, 2, 2) == 3) {
+            if (cpu_isar_feature(aa64_rme, env_archcpu(env))) {
+                return ARMSS_Root;
+            } else {
+                return ARMSS_Secure;
+            }
+        }
+    } else {
+        if ((env->uncached_cpsr & CPSR_M) == ARM_CPU_MODE_MON) {
+            return ARMSS_Secure;
+        }
+    }
+
+    return arm_security_space_below_el3(env);
+}
+
+ARMSecuritySpace arm_security_space_below_el3(CPUARMState *env)
+{
+    assert(!arm_feature(env, ARM_FEATURE_M));
+
+    /*
+     * If EL3 is not supported then the secure state is implementation
+     * defined, in which case QEMU defaults to non-secure.
+     */
+    if (!arm_feature(env, ARM_FEATURE_EL3)) {
+        return ARMSS_NonSecure;
+    }
+
+    /*
+     * Note NSE cannot be set without RME, and NSE & !NS is Reserved.
+     * Ignoring NSE when !NS retains consistency without having to
+     * modify other predicates.
+     */
+    if (!(env->cp15.scr_el3 & SCR_NS)) {
+        return ARMSS_Secure;
+    } else if (env->cp15.scr_el3 & SCR_NSE) {
+        return ARMSS_Realm;
+    } else {
+        return ARMSS_NonSecure;
+    }
+}
+#endif /* !CONFIG_USER_ONLY */