target-xtensa: implement relocatable vectors

See ISA, 4.4.3 for details.

Vector addresses recorded in core configuration are absolute values that
correspond to default VECBASE value.
Signed-off-by: NMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

target-xtensa/cpu.h

@@ -123,6 +123,7 @@ enum {
     INTCLEAR = 227,
     INTENABLE = 228,
     PS = 230,
+    VECBASE = 231,
     EXCCAUSE = 232,
     CCOUNT = 234,
     PRID = 235,
@@ -219,6 +220,7 @@ typedef struct XtensaConfig {
     unsigned nareg;
     int excm_level;
     int ndepc;
+    uint32_t vecbase;
     uint32_t exception_vector[EXC_MAX];
     unsigned ninterrupt;
     unsigned nlevel;

target-xtensa/helper.c

@@ -41,6 +41,7 @@ void cpu_reset(CPUXtensaState *env)
     env->sregs[LITBASE] &= ~1;
     env->sregs[PS] = xtensa_option_enabled(env->config,
             XTENSA_OPTION_INTERRUPT) ? 0x1f : 0x10;
+    env->sregs[VECBASE] = env->config->vecbase;
 
     env->pending_irq_level = 0;
 }
@@ -54,6 +55,7 @@ static const XtensaConfig core_config[] = {
         .nareg = 64,
         .ndepc = 1,
         .excm_level = 16,
+        .vecbase = 0x5fff8400,
         .exception_vector = {
             [EXC_RESET] = 0x5fff8000,
             [EXC_WINDOW_OVERFLOW4] = 0x5fff8400,
@@ -140,6 +142,16 @@ target_phys_addr_t cpu_get_phys_page_debug(CPUState *env, target_ulong addr)
     return addr;
 }
 
+static uint32_t relocated_vector(CPUState *env, uint32_t vector)
+{
+    if (xtensa_option_enabled(env->config,
+                XTENSA_OPTION_RELOCATABLE_VECTOR)) {
+        return vector - env->config->vecbase + env->sregs[VECBASE];
+    } else {
+        return vector;
+    }
+}
+
 /*!
  * Handle penging IRQ.
  * For the high priority interrupt jump to the corresponding interrupt vector.
@@ -160,7 +172,8 @@ static void handle_interrupt(CPUState *env)
             env->sregs[EPS2 + level - 2] = env->sregs[PS];
             env->sregs[PS] =
                 (env->sregs[PS] & ~PS_INTLEVEL) | level | PS_EXCM;
-            env->pc = env->config->interrupt_vector[level];
+            env->pc = relocated_vector(env,
+                    env->config->interrupt_vector[level]);
         } else {
             env->sregs[EXCCAUSE] = LEVEL1_INTERRUPT_CAUSE;
 
@@ -212,7 +225,8 @@ void do_interrupt(CPUState *env)
                 __func__, env->exception_index,
                 env->pc, env->regs[0], env->sregs[PS], env->sregs[CCOUNT]);
         if (env->config->exception_vector[env->exception_index]) {
-            env->pc = env->config->exception_vector[env->exception_index];
+            env->pc = relocated_vector(env,
+                    env->config->exception_vector[env->exception_index]);
             env->exception_taken = 1;
         } else {
             qemu_log("%s(pc = %08x) bad exception_index: %d\n",

target-xtensa/translate.c

@@ -106,6 +106,7 @@ static const char * const sregnames[256] = {
     [INTCLEAR] = "INTCLEAR",
     [INTENABLE] = "INTENABLE",
     [PS] = "PS",
+    [VECBASE] = "VECBASE",
     [EXCCAUSE] = "EXCCAUSE",
     [CCOUNT] = "CCOUNT",
     [PRID] = "PRID",