3 files changed, 114 insertions, 1 deletions

diff --git a/hw/intc/armv7m_nvic.c b/hw/intc/armv7m_nvic.c
index 5eb438f540..53b4631dac 100644
--- a/hw/intc/armv7m_nvic.c
+++ b/hw/intc/armv7m_nvic.c
@@ -746,6 +746,40 @@ int armv7m_nvic_complete_irq(void *opaque, int irq, bool secure)
     return ret;
 }
 
+bool armv7m_nvic_get_ready_status(void *opaque, int irq, bool secure)
+{
+    /*
+     * Return whether an exception is "ready", i.e. it is enabled and is
+     * configured at a priority which would allow it to interrupt the
+     * current execution priority.
+     *
+     * irq and secure have the same semantics as for armv7m_nvic_set_pending():
+     * for non-banked exceptions secure is always false; for banked exceptions
+     * it indicates which of the exceptions is required.
+     */
+    NVICState *s = (NVICState *)opaque;
+    bool banked = exc_is_banked(irq);
+    VecInfo *vec;
+    int running = nvic_exec_prio(s);
+
+    assert(irq > ARMV7M_EXCP_RESET && irq < s->num_irq);
+    assert(!secure || banked);
+
+    /*
+     * HardFault is an odd special case: we always check against -1,
+     * even if we're secure and HardFault has priority -3; we never
+     * need to check for enabled state.
+     */
+    if (irq == ARMV7M_EXCP_HARD) {
+        return running > -1;
+    }
+
+    vec = (banked && secure) ? &s->sec_vectors[irq] : &s->vectors[irq];
+
+    return vec->enabled &&
+        exc_group_prio(s, vec->prio, secure) < running;
+}
+
 /* callback when external interrupt line is changed */
 static void set_irq_level(void *opaque, int n, int level)
 {
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 67e4e95d44..eb989d773a 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -2045,6 +2045,20 @@ void armv7m_nvic_acknowledge_irq(void *opaque);
  */
 int armv7m_nvic_complete_irq(void *opaque, int irq, bool secure);
 /**
+ * armv7m_nvic_get_ready_status(void *opaque, int irq, bool secure)
+ * @opaque: the NVIC
+ * @irq: the exception number to mark pending
+ * @secure: false for non-banked exceptions or for the nonsecure
+ * version of a banked exception, true for the secure version of a banked
+ * exception.
+ *
+ * Return whether an exception is "ready", i.e. whether the exception is
+ * enabled and is configured at a priority which would allow it to
+ * interrupt the current execution priority. This controls whether the
+ * RDY bit for it in the FPCCR is set.
+ */
+bool armv7m_nvic_get_ready_status(void *opaque, int irq, bool secure);
+/**
  * armv7m_nvic_raw_execution_priority: return the raw execution priority
  * @opaque: the NVIC
  *
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 6e55da5c48..547898581a 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -8177,6 +8177,71 @@ static void v7m_exception_taken(ARMCPU *cpu, uint32_t lr, bool dotailchain,
     env->thumb = addr & 1;
 }
 
+static void v7m_update_fpccr(CPUARMState *env, uint32_t frameptr,
+                             bool apply_splim)
+{
+    /*
+     * Like the pseudocode UpdateFPCCR: save state in FPCAR and FPCCR
+     * that we will need later in order to do lazy FP reg stacking.
+     */
+    bool is_secure = env->v7m.secure;
+    void *nvic = env->nvic;
+    /*
+     * Some bits are unbanked and live always in fpccr[M_REG_S]; some bits
+     * are banked and we want to update the bit in the bank for the
+     * current security state; and in one case we want to specifically
+     * update the NS banked version of a bit even if we are secure.
+     */
+    uint32_t *fpccr_s = &env->v7m.fpccr[M_REG_S];
+    uint32_t *fpccr_ns = &env->v7m.fpccr[M_REG_NS];
+    uint32_t *fpccr = &env->v7m.fpccr[is_secure];
+    bool hfrdy, bfrdy, mmrdy, ns_ufrdy, s_ufrdy, sfrdy, monrdy;
+
+    env->v7m.fpcar[is_secure] = frameptr & ~0x7;
+
+    if (apply_splim && arm_feature(env, ARM_FEATURE_V8)) {
+        bool splimviol;
+        uint32_t splim = v7m_sp_limit(env);
+        bool ign = armv7m_nvic_neg_prio_requested(nvic, is_secure) &&
+            (env->v7m.ccr[is_secure] & R_V7M_CCR_STKOFHFNMIGN_MASK);
+
+        splimviol = !ign && frameptr < splim;
+        *fpccr = FIELD_DP32(*fpccr, V7M_FPCCR, SPLIMVIOL, splimviol);
+    }
+
+    *fpccr = FIELD_DP32(*fpccr, V7M_FPCCR, LSPACT, 1);
+
+    *fpccr_s = FIELD_DP32(*fpccr_s, V7M_FPCCR, S, is_secure);
+
+    *fpccr = FIELD_DP32(*fpccr, V7M_FPCCR, USER, arm_current_el(env) == 0);
+
+    *fpccr = FIELD_DP32(*fpccr, V7M_FPCCR, THREAD,
+                        !arm_v7m_is_handler_mode(env));
+
+    hfrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_HARD, false);
+    *fpccr_s = FIELD_DP32(*fpccr_s, V7M_FPCCR, HFRDY, hfrdy);
+
+    bfrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_BUS, false);
+    *fpccr_s = FIELD_DP32(*fpccr_s, V7M_FPCCR, BFRDY, bfrdy);
+
+    mmrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_MEM, is_secure);
+    *fpccr = FIELD_DP32(*fpccr, V7M_FPCCR, MMRDY, mmrdy);
+
+    ns_ufrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_USAGE, false);
+    *fpccr_ns = FIELD_DP32(*fpccr_ns, V7M_FPCCR, UFRDY, ns_ufrdy);
+
+    monrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_DEBUG, false);
+    *fpccr_s = FIELD_DP32(*fpccr_s, V7M_FPCCR, MONRDY, monrdy);
+
+    if (arm_feature(env, ARM_FEATURE_M_SECURITY)) {
+        s_ufrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_USAGE, true);
+        *fpccr_s = FIELD_DP32(*fpccr_s, V7M_FPCCR, UFRDY, s_ufrdy);
+
+        sfrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_SECURE, false);
+        *fpccr_s = FIELD_DP32(*fpccr_s, V7M_FPCCR, SFRDY, sfrdy);
+    }
+}
+
 static bool v7m_push_stack(ARMCPU *cpu)
 {
     /* Do the "set up stack frame" part of exception entry,
@@ -8324,7 +8389,7 @@ static bool v7m_push_stack(ARMCPU *cpu)
                 }
             } else {
                 /* Lazy stacking enabled, save necessary info to stack later */
-                /* TODO : equivalent of UpdateFPCCR() pseudocode */
+                v7m_update_fpccr(env, frameptr + 0x20, true);
             }
         }
     }