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>

2 files changed, 127 insertions, 22 deletions

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index c9c87b5..125e53b 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -2414,25 +2414,53 @@ static inline int arm_feature(CPUARMState *env, int feature)
 
 void arm_cpu_finalize_features(ARMCPU *cpu, Error **errp);
 
-#if !defined(CONFIG_USER_ONLY)
 /*
+ * ARM v9 security states.
+ * The ordering of the enumeration corresponds to the low 2 bits
+ * of the GPI value, and (except for Root) the concat of NSE:NS.
+ */
+
+typedef enum ARMSecuritySpace {
+    ARMSS_Secure     = 0,
+    ARMSS_NonSecure  = 1,
+    ARMSS_Root       = 2,
+    ARMSS_Realm      = 3,
+} ARMSecuritySpace;
+
+/* Return true if @space is secure, in the pre-v9 sense. */
+static inline bool arm_space_is_secure(ARMSecuritySpace space)
+{
+    return space == ARMSS_Secure || space == ARMSS_Root;
+}
+
+/* Return the ARMSecuritySpace for @secure, assuming !RME or EL[0-2]. */
+static inline ARMSecuritySpace arm_secure_to_space(bool secure)
+{
+    return secure ? ARMSS_Secure : ARMSS_NonSecure;
+}
+
+#if !defined(CONFIG_USER_ONLY)
+/**
+ * arm_security_space_below_el3:
+ * @env: cpu context
+ *
+ * Return the security space of exception levels below EL3, following
+ * an exception return to those levels.  Unlike arm_security_space,
+ * this doesn't care about the current EL.
+ */
+ARMSecuritySpace arm_security_space_below_el3(CPUARMState *env);
+
+/**
+ * arm_is_secure_below_el3:
+ * @env: cpu context
+ *
  * 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.
+ * or would be following an exception return to those levels.
  */
 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 {
-        /* If EL3 is not supported then the secure state is implementation
-         * defined, in which case QEMU defaults to non-secure.
-         */
-        return false;
-    }
+    ARMSecuritySpace ss = arm_security_space_below_el3(env);
+    return ss == ARMSS_Secure;
 }
 
 /* Return true if the CPU is AArch64 EL3 or AArch32 Mon */
@@ -2452,16 +2480,23 @@ static inline bool arm_is_el3_or_mon(CPUARMState *env)
     return false;
 }
 
-/* Return true if the processor is in secure state */
+/**
+ * arm_security_space:
+ * @env: cpu context
+ *
+ * Return the current security space of the cpu.
+ */
+ARMSecuritySpace arm_security_space(CPUARMState *env);
+
+/**
+ * arm_is_secure:
+ * @env: cpu context
+ *
+ * Return true if the processor is in secure state.
+ */
 static inline bool arm_is_secure(CPUARMState *env)
 {
-    if (arm_feature(env, ARM_FEATURE_M)) {
-        return env->v7m.secure;
-    }
-    if (arm_is_el3_or_mon(env)) {
-        return true;
-    }
-    return arm_is_secure_below_el3(env);
+    return arm_space_is_secure(arm_security_space(env));
 }
 
 /*
@@ -2480,11 +2515,21 @@ static inline bool arm_is_el2_enabled(CPUARMState *env)
 }
 
 #else
+static inline ARMSecuritySpace arm_security_space_below_el3(CPUARMState *env)
+{
+    return ARMSS_NonSecure;
+}
+
 static inline bool arm_is_secure_below_el3(CPUARMState *env)
 {
     return false;
 }
 
+static inline ARMSecuritySpace arm_security_space(CPUARMState *env)
+{
+    return ARMSS_NonSecure;
+}
+
 static inline bool arm_is_secure(CPUARMState *env)
 {
     return false;
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 006447d..f68923d 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 */