nvic: Implement AIRCR changes for v8M

The Application Interrupt and Reset Control Register has some changes
for v8M:
 * new bits SYSRESETREQS, BFHFNMINS and PRIS: these all have
   real state if the security extension is implemented and otherwise
   are constant
 * the PRIGROUP field is banked between security states
 * non-secure code can be blocked from using the SYSRESET bit
   to reset the system if SYSRESETREQS is set

Implement the new state and the changes to register read and write.
For the moment we ignore the effects of the secure PRIGROUP.
We will implement the effects of PRIS and BFHFNMIS later.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1505240046-11454-6-git-send-email-peter.maydell@linaro.org

diff --git a/hw/intc/armv7m_nvic.c b/hw/intc/armv7m_nvic.c
index fa5dd23f09dcc2e8c0469f5a6ab3a2f41dfda8cb..d745f383615d1653b11feb3a31d97817d081631b 100644 (file)
--- a/hw/intc/armv7m_nvic.c
+++ b/hw/intc/armv7m_nvic.c
@@ -129,7 +129,7 @@ static bool nvic_isrpending(NVICState *s)
  */
 static inline uint32_t nvic_gprio_mask(NVICState *s)
 {
-    return ~0U << (s->prigroup + 1);
+    return ~0U << (s->prigroup[M_REG_NS] + 1);
 }
 
 /* Recompute vectpending and exception_prio */
@@ -451,8 +451,21 @@ static uint32_t nvic_readl(NVICState *s, uint32_t offset, MemTxAttrs attrs)
         return val;
     case 0xd08: /* Vector Table Offset.  */
         return cpu->env.v7m.vecbase[attrs.secure];
-    case 0xd0c: /* Application Interrupt/Reset Control.  */
-        return 0xfa050000 | (s->prigroup << 8);
+    case 0xd0c: /* Application Interrupt/Reset Control (AIRCR) */
+        val = 0xfa050000 | (s->prigroup[attrs.secure] << 8);
+        if (attrs.secure) {
+            /* s->aircr stores PRIS, BFHFNMINS, SYSRESETREQS */
+            val |= cpu->env.v7m.aircr;
+        } else {
+            if (arm_feature(&cpu->env, ARM_FEATURE_V8)) {
+                /* BFHFNMINS is R/O from NS; other bits are RAZ/WI. If
+                 * security isn't supported then BFHFNMINS is RAO (and
+                 * the bit in env.v7m.aircr is always set).
+                 */
+                val |= cpu->env.v7m.aircr & R_V7M_AIRCR_BFHFNMINS_MASK;
+            }
+        }
+        return val;
     case 0xd10: /* System Control.  */
         /* TODO: Implement SLEEPONEXIT.  */
         return 0;
@@ -660,22 +673,35 @@ static void nvic_writel(NVICState *s, uint32_t offset, uint32_t value,
     case 0xd08: /* Vector Table Offset.  */
         cpu->env.v7m.vecbase[attrs.secure] = value & 0xffffff80;
         break;
-    case 0xd0c: /* Application Interrupt/Reset Control.  */
-        if ((value >> 16) == 0x05fa) {
-            if (value & 4) {
-                qemu_irq_pulse(s->sysresetreq);
+    case 0xd0c: /* Application Interrupt/Reset Control (AIRCR) */
+        if ((value >> R_V7M_AIRCR_VECTKEY_SHIFT) == 0x05fa) {
+            if (value & R_V7M_AIRCR_SYSRESETREQ_MASK) {
+                if (attrs.secure ||
+                    !(cpu->env.v7m.aircr & R_V7M_AIRCR_SYSRESETREQS_MASK)) {
+                    qemu_irq_pulse(s->sysresetreq);
+                }
             }
-            if (value & 2) {
+            if (value & R_V7M_AIRCR_VECTCLRACTIVE_MASK) {
                 qemu_log_mask(LOG_GUEST_ERROR,
                               "Setting VECTCLRACTIVE when not in DEBUG mode "
                               "is UNPREDICTABLE\n");
             }
-            if (value & 1) {
+            if (value & R_V7M_AIRCR_VECTRESET_MASK) {
+                /* NB: this bit is RES0 in v8M */
                 qemu_log_mask(LOG_GUEST_ERROR,
                               "Setting VECTRESET when not in DEBUG mode "
                               "is UNPREDICTABLE\n");
             }
-            s->prigroup = extract32(value, 8, 3);
+            s->prigroup[attrs.secure] = extract32(value,
+                                                  R_V7M_AIRCR_PRIGROUP_SHIFT,
+                                                  R_V7M_AIRCR_PRIGROUP_LENGTH);
+            if (attrs.secure) {
+                /* These bits are only writable by secure */
+                cpu->env.v7m.aircr = value &
+                    (R_V7M_AIRCR_SYSRESETREQS_MASK |
+                     R_V7M_AIRCR_BFHFNMINS_MASK |
+                     R_V7M_AIRCR_PRIS_MASK);
+            }
             nvic_irq_update(s);
         }
         break;
@@ -1193,6 +1219,7 @@ static const VMStateDescription vmstate_nvic_security = {
     .fields = (VMStateField[]) {
         VMSTATE_STRUCT_ARRAY(sec_vectors, NVICState, NVIC_INTERNAL_VECTORS, 1,
                              vmstate_VecInfo, VecInfo),
+        VMSTATE_UINT32(prigroup[M_REG_S], NVICState),
         VMSTATE_END_OF_LIST()
     }
 };
@@ -1205,7 +1232,7 @@ static const VMStateDescription vmstate_nvic = {
     .fields = (VMStateField[]) {
         VMSTATE_STRUCT_ARRAY(vectors, NVICState, NVIC_MAX_VECTORS, 1,
                              vmstate_VecInfo, VecInfo),
-        VMSTATE_UINT32(prigroup, NVICState),
+        VMSTATE_UINT32(prigroup[M_REG_NS], NVICState),
         VMSTATE_END_OF_LIST()
     },
     .subsections = (const VMStateDescription*[]) {

diff --git a/include/hw/intc/armv7m_nvic.h b/include/hw/intc/armv7m_nvic.h
index 329774e82b0a152a105af432e756bb86c2cbf3eb..e96e488c775cde7c9c4c9e78f2a229fec7ce37e1 100644 (file)
--- a/include/hw/intc/armv7m_nvic.h
+++ b/include/hw/intc/armv7m_nvic.h
@@ -55,7 +55,8 @@ typedef struct NVICState {
      * Entries in sec_vectors[] for non-banked exception numbers are unused.
      */
     VecInfo sec_vectors[NVIC_INTERNAL_VECTORS];
-    uint32_t prigroup;
+    /* The PRIGROUP field in AIRCR is banked */
+    uint32_t prigroup[M_REG_NUM_BANKS];
 
     /* The following fields are all cached state that can be recalculated
      * from the vectors[] and sec_vectors[] arrays and the prigroup field:

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 20a3445bdab05bf1a4e1aecac0ed8922eb0e2be5..33449790e5496aba7244996cd578326b5f7f3ef3 100644 (file)
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -187,6 +187,13 @@ static void arm_cpu_reset(CPUState *s)
 
         if (arm_feature(env, ARM_FEATURE_M_SECURITY)) {
             env->v7m.secure = true;
+        } else {
+            /* This bit resets to 0 if security is supported, but 1 if
+             * it is not. The bit is not present in v7M, but we set it
+             * here so we can avoid having to make checks on it conditional
+             * on ARM_FEATURE_V8 (we don't let the guest see the bit).
+             */
+            env->v7m.aircr = R_V7M_AIRCR_BFHFNMINS_MASK;
         }
 
         /* In v7M the reset value of this bit is IMPDEF, but ARM recommends

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 6e50ae2b55595cb6aefcc040889952e7c1331a89..a52ec6b72b2886f6d6faebf2140caa2008ee0003 100644 (file)
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -449,6 +449,7 @@ typedef struct CPUARMState {
         int exception;
         uint32_t primask[M_REG_NUM_BANKS];
         uint32_t faultmask[M_REG_NUM_BANKS];
+        uint32_t aircr; /* only holds r/w state if security extn implemented */
         uint32_t secure; /* Is CPU in Secure state? (not guest visible) */
     } v7m;
 
@@ -1200,6 +1201,17 @@ FIELD(V7M_CCR, STKALIGN, 9, 1)
 FIELD(V7M_CCR, DC, 16, 1)
 FIELD(V7M_CCR, IC, 17, 1)
 
+/* V7M AIRCR bits */
+FIELD(V7M_AIRCR, VECTRESET, 0, 1)
+FIELD(V7M_AIRCR, VECTCLRACTIVE, 1, 1)
+FIELD(V7M_AIRCR, SYSRESETREQ, 2, 1)
+FIELD(V7M_AIRCR, SYSRESETREQS, 3, 1)
+FIELD(V7M_AIRCR, PRIGROUP, 8, 3)
+FIELD(V7M_AIRCR, BFHFNMINS, 13, 1)
+FIELD(V7M_AIRCR, PRIS, 14, 1)
+FIELD(V7M_AIRCR, ENDIANNESS, 15, 1)
+FIELD(V7M_AIRCR, VECTKEY, 16, 16)
+
 /* V7M CFSR bits for MMFSR */
 FIELD(V7M_CFSR, IACCVIOL, 0, 1)
 FIELD(V7M_CFSR, DACCVIOL, 1, 1)