target/arm: Unify checking for M Main Extension in MRS/MSR

BASEPRI, FAULTMASK, and their _NS equivalents only exist on devices with
the Main Extension.  However, the MRS instruction did not check this,
and the MSR instruction handled it inconsistently (warning BASEPRI, but
silently ignoring writes to BASEPRI_NS).  Unify this behavior and always
warn when reading or writing any of these registers if the extension is
not present.

Signed-off-by: David Reiss <dreiss@meta.com>
Message-id: 167330628518.10497.13100425787268927786-0@git.sr.ht
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/target/arm/m_helper.c b/target/arm/m_helper.c
index 033a4d92614ae6a76b4079eef38d432db6171133..d87b9ecd12334f1e3263cf9e14bd27f509c39ec4 100644 (file)
--- a/target/arm/m_helper.c
+++ b/target/arm/m_helper.c
@@ -2465,11 +2465,17 @@ uint32_t HELPER(v7m_mrs)(CPUARMState *env, uint32_t reg)
             }
             return env->v7m.primask[M_REG_NS];
         case 0x91: /* BASEPRI_NS */
+            if (!arm_feature(env, ARM_FEATURE_M_MAIN)) {
+                goto bad_reg;
+            }
             if (!env->v7m.secure) {
                 return 0;
             }
             return env->v7m.basepri[M_REG_NS];
         case 0x93: /* FAULTMASK_NS */
+            if (!arm_feature(env, ARM_FEATURE_M_MAIN)) {
+                goto bad_reg;
+            }
             if (!env->v7m.secure) {
                 return 0;
             }
@@ -2515,8 +2521,14 @@ uint32_t HELPER(v7m_mrs)(CPUARMState *env, uint32_t reg)
         return env->v7m.primask[env->v7m.secure];
     case 17: /* BASEPRI */
     case 18: /* BASEPRI_MAX */
+        if (!arm_feature(env, ARM_FEATURE_M_MAIN)) {
+            goto bad_reg;
+        }
         return env->v7m.basepri[env->v7m.secure];
     case 19: /* FAULTMASK */
+        if (!arm_feature(env, ARM_FEATURE_M_MAIN)) {
+            goto bad_reg;
+        }
         return env->v7m.faultmask[env->v7m.secure];
     default:
     bad_reg:
@@ -2581,13 +2593,19 @@ void HELPER(v7m_msr)(CPUARMState *env, uint32_t maskreg, uint32_t val)
             env->v7m.primask[M_REG_NS] = val & 1;
             return;
         case 0x91: /* BASEPRI_NS */
-            if (!env->v7m.secure || !arm_feature(env, ARM_FEATURE_M_MAIN)) {
+            if (!arm_feature(env, ARM_FEATURE_M_MAIN)) {
+                goto bad_reg;
+            }
+            if (!env->v7m.secure) {
                 return;
             }
             env->v7m.basepri[M_REG_NS] = val & 0xff;
             return;
         case 0x93: /* FAULTMASK_NS */
-            if (!env->v7m.secure || !arm_feature(env, ARM_FEATURE_M_MAIN)) {
+            if (!arm_feature(env, ARM_FEATURE_M_MAIN)) {
+                goto bad_reg;
+            }
+            if (!env->v7m.secure) {
                 return;
             }
             env->v7m.faultmask[M_REG_NS] = val & 1;