target-arm: A64: Refactor aarch64_cpu_do_interrupt

Introduce new_el and new_mode in preparation for future patches
that add support for taking exceptions to and from EL2 and 3.
No functional change.
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NEdgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 1411718914-6608-4-git-send-email-edgar.iglesias@gmail.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

target-arm/cpu.h

@@ -500,6 +500,12 @@ void pmccntr_sync(CPUARMState *env);
 #define PSTATE_MODE_EL1t 4
 #define PSTATE_MODE_EL0t 0
 
+/* Map EL and handler into a PSTATE_MODE.  */
+static inline unsigned int aarch64_pstate_mode(unsigned int el, bool handler)
+{
+    return (el << 2) | handler;
+}
+
 /* Return the current PSTATE value. For the moment we don't support 32<->64 bit
  * interprocessing, so we don't attempt to sync with the cpsr state used by
  * the 32 bit decoder.
@@ -755,6 +761,7 @@ static inline bool arm_el_is_aa64(CPUARMState *env, int el)
 }
 
 void arm_cpu_list(FILE *f, fprintf_function cpu_fprintf);
+unsigned int arm_excp_target_el(CPUState *cs, unsigned int excp_idx);
 
 /* Interface between CPU and Interrupt controller.  */
 void armv7m_nvic_set_pending(void *opaque, int irq);

target-arm/helper-a64.c

@@ -443,10 +443,12 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;
-    target_ulong addr = env->cp15.vbar_el[1];
+    unsigned int new_el = arm_excp_target_el(cs, cs->exception_index);
+    target_ulong addr = env->cp15.vbar_el[new_el];
+    unsigned int new_mode = aarch64_pstate_mode(new_el, true);
     int i;
 
-    if (arm_current_pl(env) == 0) {
+    if (arm_current_pl(env) < new_el) {
         if (env->aarch64) {
             addr += 0x400;
         } else {
@@ -464,14 +466,14 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
                       env->exception.syndrome);
     }
 
-    env->cp15.esr_el[1] = env->exception.syndrome;
-    env->cp15.far_el[1] = env->exception.vaddress;
+    env->cp15.esr_el[new_el] = env->exception.syndrome;
+    env->cp15.far_el[new_el] = env->exception.vaddress;
 
     switch (cs->exception_index) {
     case EXCP_PREFETCH_ABORT:
     case EXCP_DATA_ABORT:
         qemu_log_mask(CPU_LOG_INT, "...with FAR 0x%" PRIx64 "\n",
-                      env->cp15.far_el[1]);
+                      env->cp15.far_el[new_el]);
         break;
     case EXCP_BKPT:
     case EXCP_UDEF:
@@ -488,15 +490,15 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
     }
 
     if (is_a64(env)) {
-        env->banked_spsr[aarch64_banked_spsr_index(1)] = pstate_read(env);
+        env->banked_spsr[aarch64_banked_spsr_index(new_el)] = pstate_read(env);
         aarch64_save_sp(env, arm_current_pl(env));
-        env->elr_el[1] = env->pc;
+        env->elr_el[new_el] = env->pc;
     } else {
         env->banked_spsr[0] = cpsr_read(env);
         if (!env->thumb) {
-            env->cp15.esr_el[1] |= 1 << 25;
+            env->cp15.esr_el[new_el] |= 1 << 25;
         }
-        env->elr_el[1] = env->regs[15];
+        env->elr_el[new_el] = env->regs[15];
 
         for (i = 0; i < 15; i++) {
             env->xregs[i] = env->regs[i];
@@ -505,9 +507,9 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
         env->condexec_bits = 0;
     }
 
-    pstate_write(env, PSTATE_DAIF | PSTATE_MODE_EL1h);
+    pstate_write(env, PSTATE_DAIF | new_mode);
     env->aarch64 = 1;
-    aarch64_restore_sp(env, 1);
+    aarch64_restore_sp(env, new_el);
 
     env->pc = addr;
     cs->interrupt_request |= CPU_INTERRUPT_EXITTB;

target-arm/helper.c

@@ -3704,6 +3704,11 @@ uint32_t HELPER(get_r13_banked)(CPUARMState *env, uint32_t mode)
     return 0;
 }
 
+unsigned int arm_excp_target_el(CPUState *cs, unsigned int excp_idx)
+{
+    return 1;
+}
+
 #else
 
 /* Map CPU modes onto saved register banks.  */
@@ -3759,6 +3764,14 @@ void switch_mode(CPUARMState *env, int mode)
     env->spsr = env->banked_spsr[i];
 }
 
+/*
+ * Determine the target EL for a given exception type.
+ */
+unsigned int arm_excp_target_el(CPUState *cs, unsigned int excp_idx)
+{
+    return 1;
+}
+
 static void v7m_push(CPUARMState *env, uint32_t val)
 {
     CPUState *cs = CPU(arm_env_get_cpu(env));