target/arm: Make BASEPRI register banked for v8M

Make the BASEPRI register banked if v8M security extensions are enabled.

Note that we do not yet implement the functionality of the new
AIRCR.PRIS bit (which allows the effect of the NS copy of BASEPRI to
be restricted).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1503414539-28762-7-git-send-email-peter.maydell@linaro.org

4 files changed, 23 insertions, 8 deletions

diff --git a/hw/intc/armv7m_nvic.c b/hw/intc/armv7m_nvic.c
index c0dbbad..2a41e5d 100644
--- a/hw/intc/armv7m_nvic.c
+++ b/hw/intc/armv7m_nvic.c
@@ -171,8 +171,8 @@ static inline int nvic_exec_prio(NVICState *s)
         running = -1;
     } else if (env->v7m.primask) {
         running = 0;
-    } else if (env->v7m.basepri > 0) {
-        running = env->v7m.basepri & nvic_gprio_mask(s);
+    } else if (env->v7m.basepri[env->v7m.secure] > 0) {
+        running = env->v7m.basepri[env->v7m.secure] & nvic_gprio_mask(s);
     } else {
         running = NVIC_NOEXC_PRIO; /* lower than any possible priority */
     }
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index d93fe96..273abc3 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -72,6 +72,18 @@
 #define ARMV7M_EXCP_PENDSV  14
 #define ARMV7M_EXCP_SYSTICK 15
 
+/* For M profile, some registers are banked secure vs non-secure;
+ * these are represented as a 2-element array where the first element
+ * is the non-secure copy and the second is the secure copy.
+ * When the CPU does not have implement the security extension then
+ * only the first element is used.
+ * This means that the copy for the current security state can be
+ * accessed via env->registerfield[env->v7m.secure] (whether the security
+ * extension is implemented or not).
+ */
+#define M_REG_NS 0
+#define M_REG_S 1
+
 /* ARM-specific interrupt pending bits.  */
 #define CPU_INTERRUPT_FIQ   CPU_INTERRUPT_TGT_EXT_1
 #define CPU_INTERRUPT_VIRQ  CPU_INTERRUPT_TGT_EXT_2
@@ -409,7 +421,7 @@ typedef struct CPUARMState {
     struct {
         uint32_t other_sp;
         uint32_t vecbase;
-        uint32_t basepri;
+        uint32_t basepri[2];
         uint32_t control;
         uint32_t ccr; /* Configuration and Control */
         uint32_t cfsr; /* Configurable Fault Status */
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 3062c47..7007266 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -8833,7 +8833,7 @@ uint32_t HELPER(v7m_mrs)(CPUARMState *env, uint32_t reg)
         return env->v7m.primask;
     case 17: /* BASEPRI */
     case 18: /* BASEPRI_MAX */
-        return env->v7m.basepri;
+        return env->v7m.basepri[env->v7m.secure];
     case 19: /* FAULTMASK */
         return env->v7m.faultmask;
     default:
@@ -8893,12 +8893,14 @@ void HELPER(v7m_msr)(CPUARMState *env, uint32_t maskreg, uint32_t val)
         env->v7m.primask = val & 1;
         break;
     case 17: /* BASEPRI */
-        env->v7m.basepri = val & 0xff;
+        env->v7m.basepri[env->v7m.secure] = val & 0xff;
         break;
     case 18: /* BASEPRI_MAX */
         val &= 0xff;
-        if (val != 0 && (val < env->v7m.basepri || env->v7m.basepri == 0))
-            env->v7m.basepri = val;
+        if (val != 0 && (val < env->v7m.basepri[env->v7m.secure]
+                         || env->v7m.basepri[env->v7m.secure] == 0)) {
+            env->v7m.basepri[env->v7m.secure] = val;
+        }
         break;
     case 19: /* FAULTMASK */
         env->v7m.faultmask = val & 1;
diff --git a/target/arm/machine.c b/target/arm/machine.c
index f70fcf3..dbb432d 100644
--- a/target/arm/machine.c
+++ b/target/arm/machine.c
@@ -115,7 +115,7 @@ static const VMStateDescription vmstate_m = {
     .needed = m_needed,
     .fields = (VMStateField[]) {
         VMSTATE_UINT32(env.v7m.vecbase, ARMCPU),
-        VMSTATE_UINT32(env.v7m.basepri, ARMCPU),
+        VMSTATE_UINT32(env.v7m.basepri[M_REG_NS], ARMCPU),
         VMSTATE_UINT32(env.v7m.control, ARMCPU),
         VMSTATE_UINT32(env.v7m.ccr, ARMCPU),
         VMSTATE_UINT32(env.v7m.cfsr, ARMCPU),
@@ -250,6 +250,7 @@ static const VMStateDescription vmstate_m_security = {
     .needed = m_security_needed,
     .fields = (VMStateField[]) {
         VMSTATE_UINT32(env.v7m.secure, ARMCPU),
+        VMSTATE_UINT32(env.v7m.basepri[M_REG_S], ARMCPU),
         VMSTATE_END_OF_LIST()
     }
 };