3 files changed, 565 insertions, 10 deletions

diff --git a/target-s390x/helper.c b/target-s390x/helper.c
index 629dfd9..c79af46 100644
--- a/target-s390x/helper.c
+++ b/target-s390x/helper.c
@@ -2,6 +2,7 @@
  *  S/390 helpers
  *
  *  Copyright (c) 2009 Ulrich Hecht
+ *  Copyright (c) 2011 Alexander Graf
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -25,27 +26,107 @@
 #include "exec-all.h"
 #include "gdbstub.h"
 #include "qemu-common.h"
+#include "qemu-timer.h"
 
+#if !defined(CONFIG_USER_ONLY)
 #include <linux/kvm.h>
 #include "kvm.h"
+#endif
+
+//#define DEBUG_S390
+//#define DEBUG_S390_PTE
+//#define DEBUG_S390_STDOUT
+
+#ifdef DEBUG_S390
+#ifdef DEBUG_S390_STDOUT
+#define DPRINTF(fmt, ...) \
+    do { fprintf(stderr, fmt, ## __VA_ARGS__); \
+         qemu_log(fmt, ##__VA_ARGS__); } while (0)
+#else
+#define DPRINTF(fmt, ...) \
+    do { qemu_log(fmt, ## __VA_ARGS__); } while (0)
+#endif
+#else
+#define DPRINTF(fmt, ...) \
+    do { } while (0)
+#endif
+
+#ifdef DEBUG_S390_PTE
+#define PTE_DPRINTF DPRINTF
+#else
+#define PTE_DPRINTF(fmt, ...) \
+    do { } while (0)
+#endif
+
+#ifndef CONFIG_USER_ONLY
+static void s390x_tod_timer(void *opaque)
+{
+    CPUState *env = opaque;
+
+    env->pending_int |= INTERRUPT_TOD;
+    cpu_interrupt(env, CPU_INTERRUPT_HARD);
+}
+
+static void s390x_cpu_timer(void *opaque)
+{
+    CPUState *env = opaque;
+
+    env->pending_int |= INTERRUPT_CPUTIMER;
+    cpu_interrupt(env, CPU_INTERRUPT_HARD);
+}
+#endif
 
 CPUS390XState *cpu_s390x_init(const char *cpu_model)
 {
     CPUS390XState *env;
+#if !defined (CONFIG_USER_ONLY)
+    struct tm tm;
+#endif
     static int inited = 0;
+    static int cpu_num = 0;
 
     env = qemu_mallocz(sizeof(CPUS390XState));
     cpu_exec_init(env);
     if (!inited) {
         inited = 1;
+        s390x_translate_init();
     }
 
+#if !defined(CONFIG_USER_ONLY)
+    qemu_get_timedate(&tm, 0);
+    env->tod_offset = TOD_UNIX_EPOCH +
+                      (time2tod(mktimegm(&tm)) * 1000000000ULL);
+    env->tod_basetime = 0;
+    env->tod_timer = qemu_new_timer_ns(vm_clock, s390x_tod_timer, env);
+    env->cpu_timer = qemu_new_timer_ns(vm_clock, s390x_cpu_timer, env);
+#endif
     env->cpu_model_str = cpu_model;
+    env->cpu_num = cpu_num++;
+    env->ext_index = -1;
     cpu_reset(env);
     qemu_init_vcpu(env);
     return env;
 }
 
+#if defined(CONFIG_USER_ONLY)
+
+void do_interrupt (CPUState *env)
+{
+    env->exception_index = -1;
+}
+
+int cpu_s390x_handle_mmu_fault (CPUState *env, target_ulong address, int rw,
+                              int mmu_idx, int is_softmmu)
+{
+    /* fprintf(stderr,"%s: address 0x%lx rw %d mmu_idx %d is_softmmu %d\n",
+            __FUNCTION__, address, rw, mmu_idx, is_softmmu); */
+    env->exception_index = EXCP_ADDR;
+    env->__excp_addr = address; /* FIXME: find out how this works on a real machine */
+    return 1;
+}
+
+#endif /* CONFIG_USER_ONLY */
+
 void cpu_reset(CPUS390XState *env)
 {
     if (qemu_loglevel_mask(CPU_LOG_RESET)) {
@@ -58,31 +139,495 @@ void cpu_reset(CPUS390XState *env)
     tlb_flush(env, 1);
 }
 
-target_phys_addr_t cpu_get_phys_page_debug(CPUState *env, target_ulong addr)
+#ifndef CONFIG_USER_ONLY
+
+/* Ensure to exit the TB after this call! */
+static void trigger_pgm_exception(CPUState *env, uint32_t code, uint32_t ilc)
+{
+    env->exception_index = EXCP_PGM;
+    env->int_pgm_code = code;
+    env->int_pgm_ilc = ilc;
+}
+
+static int trans_bits(CPUState *env, uint64_t mode)
+{
+    int bits = 0;
+
+    switch (mode) {
+    case PSW_ASC_PRIMARY:
+        bits = 1;
+        break;
+    case PSW_ASC_SECONDARY:
+        bits = 2;
+        break;
+    case PSW_ASC_HOME:
+        bits = 3;
+        break;
+    default:
+        cpu_abort(env, "unknown asc mode\n");
+        break;
+    }
+
+    return bits;
+}
+
+static void trigger_prot_fault(CPUState *env, target_ulong vaddr, uint64_t mode)
+{
+    int ilc = ILC_LATER_INC_2;
+    int bits = trans_bits(env, mode) | 4;
+
+    DPRINTF("%s: vaddr=%016" PRIx64 " bits=%d\n", __FUNCTION__, vaddr, bits);
+
+    stq_phys(env->psa + offsetof(LowCore, trans_exc_code), vaddr | bits);
+    trigger_pgm_exception(env, PGM_PROTECTION, ilc);
+}
+
+static void trigger_page_fault(CPUState *env, target_ulong vaddr, uint32_t type,
+                               uint64_t asc, int rw)
+{
+    int ilc = ILC_LATER;
+    int bits = trans_bits(env, asc);
+
+    if (rw == 2) {
+        /* code has is undefined ilc */
+        ilc = 2;
+    }
+
+    DPRINTF("%s: vaddr=%016" PRIx64 " bits=%d\n", __FUNCTION__, vaddr, bits);
+
+    stq_phys(env->psa + offsetof(LowCore, trans_exc_code), vaddr | bits);
+    trigger_pgm_exception(env, type, ilc);
+}
+
+static int mmu_translate_asce(CPUState *env, target_ulong vaddr, uint64_t asc,
+                              uint64_t asce, int level, target_ulong *raddr,
+                              int *flags, int rw)
 {
+    uint64_t offs = 0;
+    uint64_t origin;
+    uint64_t new_asce;
+
+    PTE_DPRINTF("%s: 0x%" PRIx64 "\n", __FUNCTION__, asce);
+
+    if (((level != _ASCE_TYPE_SEGMENT) && (asce & _REGION_ENTRY_INV)) ||
+        ((level == _ASCE_TYPE_SEGMENT) && (asce & _SEGMENT_ENTRY_INV))) {
+        /* XXX different regions have different faults */
+        DPRINTF("%s: invalid region\n", __FUNCTION__);
+        trigger_page_fault(env, vaddr, PGM_SEGMENT_TRANS, asc, rw);
+        return -1;
+    }
+
+    if ((level <= _ASCE_TYPE_MASK) && ((asce & _ASCE_TYPE_MASK) != level)) {
+        trigger_page_fault(env, vaddr, PGM_TRANS_SPEC, asc, rw);
+        return -1;
+    }
+
+    if (asce & _ASCE_REAL_SPACE) {
+        /* direct mapping */
+
+        *raddr = vaddr;
+        return 0;
+    }
+
+    origin = asce & _ASCE_ORIGIN;
+
+    switch (level) {
+    case _ASCE_TYPE_REGION1 + 4:
+        offs = (vaddr >> 50) & 0x3ff8;
+        break;
+    case _ASCE_TYPE_REGION1:
+        offs = (vaddr >> 39) & 0x3ff8;
+        break;
+    case _ASCE_TYPE_REGION2:
+        offs = (vaddr >> 28) & 0x3ff8;
+        break;
+    case _ASCE_TYPE_REGION3:
+        offs = (vaddr >> 17) & 0x3ff8;
+        break;
+    case _ASCE_TYPE_SEGMENT:
+        offs = (vaddr >> 9) & 0x07f8;
+        origin = asce & _SEGMENT_ENTRY_ORIGIN;
+        break;
+    }
+
+    /* XXX region protection flags */
+    /* *flags &= ~PAGE_WRITE */
+
+    new_asce = ldq_phys(origin + offs);
+    PTE_DPRINTF("%s: 0x%" PRIx64 " + 0x%" PRIx64 " => 0x%016" PRIx64 "\n",
+                __FUNCTION__, origin, offs, new_asce);
+
+    if (level != _ASCE_TYPE_SEGMENT) {
+        /* yet another region */
+        return mmu_translate_asce(env, vaddr, asc, new_asce, level - 4, raddr,
+                                  flags, rw);
+    }
+
+    /* PTE */
+    if (new_asce & _PAGE_INVALID) {
+        DPRINTF("%s: PTE=0x%" PRIx64 " invalid\n", __FUNCTION__, new_asce);
+        trigger_page_fault(env, vaddr, PGM_PAGE_TRANS, asc, rw);
+        return -1;
+    }
+
+    if (new_asce & _PAGE_RO) {
+        *flags &= ~PAGE_WRITE;
+    }
+
+    *raddr = new_asce & _ASCE_ORIGIN;
+
+    PTE_DPRINTF("%s: PTE=0x%" PRIx64 "\n", __FUNCTION__, new_asce);
+
     return 0;
 }
 
-#ifndef CONFIG_USER_ONLY
+static int mmu_translate_asc(CPUState *env, target_ulong vaddr, uint64_t asc,
+                             target_ulong *raddr, int *flags, int rw)
+{
+    uint64_t asce = 0;
+    int level, new_level;
+    int r;
 
-int cpu_s390x_handle_mmu_fault (CPUState *env, target_ulong address, int rw,
+    switch (asc) {
+    case PSW_ASC_PRIMARY:
+        PTE_DPRINTF("%s: asc=primary\n", __FUNCTION__);
+        asce = env->cregs[1];
+        break;
+    case PSW_ASC_SECONDARY:
+        PTE_DPRINTF("%s: asc=secondary\n", __FUNCTION__);
+        asce = env->cregs[7];
+        break;
+    case PSW_ASC_HOME:
+        PTE_DPRINTF("%s: asc=home\n", __FUNCTION__);
+        asce = env->cregs[13];
+        break;
+    }
+
+    switch (asce & _ASCE_TYPE_MASK) {
+    case _ASCE_TYPE_REGION1:
+        break;
+    case _ASCE_TYPE_REGION2:
+        if (vaddr & 0xffe0000000000000ULL) {
+            DPRINTF("%s: vaddr doesn't fit 0x%16" PRIx64
+                        " 0xffe0000000000000ULL\n", __FUNCTION__,
+                        vaddr);
+            trigger_page_fault(env, vaddr, PGM_TRANS_SPEC, asc, rw);
+            return -1;
+        }
+        break;
+    case _ASCE_TYPE_REGION3:
+        if (vaddr & 0xfffffc0000000000ULL) {
+            DPRINTF("%s: vaddr doesn't fit 0x%16" PRIx64
+                        " 0xfffffc0000000000ULL\n", __FUNCTION__,
+                        vaddr);
+            trigger_page_fault(env, vaddr, PGM_TRANS_SPEC, asc, rw);
+            return -1;
+        }
+        break;
+    case _ASCE_TYPE_SEGMENT:
+        if (vaddr & 0xffffffff80000000ULL) {
+            DPRINTF("%s: vaddr doesn't fit 0x%16" PRIx64
+                        " 0xffffffff80000000ULL\n", __FUNCTION__,
+                        vaddr);
+            trigger_page_fault(env, vaddr, PGM_TRANS_SPEC, asc, rw);
+            return -1;
+        }
+        break;
+    }
+
+    /* fake level above current */
+    level = asce & _ASCE_TYPE_MASK;
+    new_level = level + 4;
+    asce = (asce & ~_ASCE_TYPE_MASK) | (new_level & _ASCE_TYPE_MASK);
+
+    r = mmu_translate_asce(env, vaddr, asc, asce, new_level, raddr, flags, rw);
+
+    if ((rw == 1) && !(*flags & PAGE_WRITE)) {
+        trigger_prot_fault(env, vaddr, asc);
+        return -1;
+    }
+
+    return r;
+}
+
+int mmu_translate(CPUState *env, target_ulong vaddr, int rw, uint64_t asc,
+                  target_ulong *raddr, int *flags)
+{
+    int r = -1;
+
+    *flags = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
+    vaddr &= TARGET_PAGE_MASK;
+
+    if (!(env->psw.mask & PSW_MASK_DAT)) {
+        *raddr = vaddr;
+        r = 0;
+        goto out;
+    }
+
+    switch (asc) {
+    case PSW_ASC_PRIMARY:
+    case PSW_ASC_HOME:
+        r = mmu_translate_asc(env, vaddr, asc, raddr, flags, rw);
+        break;
+    case PSW_ASC_SECONDARY:
+        /*
+         * Instruction: Primary
+         * Data: Secondary
+         */
+        if (rw == 2) {
+            r = mmu_translate_asc(env, vaddr, PSW_ASC_PRIMARY, raddr, flags,
+                                  rw);
+            *flags &= ~(PAGE_READ | PAGE_WRITE);
+        } else {
+            r = mmu_translate_asc(env, vaddr, PSW_ASC_SECONDARY, raddr, flags,
+                                  rw);
+            *flags &= ~(PAGE_EXEC);
+        }
+        break;
+    case PSW_ASC_ACCREG:
+    default:
+        hw_error("guest switched to unknown asc mode\n");
+        break;
+    }
+
+out:
+    /* Convert real address -> absolute address */
+    if (*raddr < 0x2000) {
+        *raddr = *raddr + env->psa;
+    }
+
+    return r;
+}
+
+int cpu_s390x_handle_mmu_fault (CPUState *env, target_ulong _vaddr, int rw,
                                 int mmu_idx, int is_softmmu)
 {
-    target_ulong phys;
+    uint64_t asc = env->psw.mask & PSW_MASK_ASC;
+    target_ulong vaddr, raddr;
     int prot;
 
-    /* XXX: implement mmu */
+    DPRINTF("%s: address 0x%" PRIx64 " rw %d mmu_idx %d is_softmmu %d\n",
+            __FUNCTION__, _vaddr, rw, mmu_idx, is_softmmu);
+
+    _vaddr &= TARGET_PAGE_MASK;
+    vaddr = _vaddr;
+
+    /* 31-Bit mode */
+    if (!(env->psw.mask & PSW_MASK_64)) {
+        vaddr &= 0x7fffffff;
+    }
+
+    if (mmu_translate(env, vaddr, rw, asc, &raddr, &prot)) {
+        /* Translation ended in exception */
+        return 1;
+    }
 
-    phys = address;
-    prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
+    /* check out of RAM access */
+    if (raddr > (ram_size + virtio_size)) {
+        DPRINTF("%s: aaddr %" PRIx64 " > ram_size %" PRIx64 "\n", __FUNCTION__,
+                (uint64_t)aaddr, (uint64_t)ram_size);
+        trigger_pgm_exception(env, PGM_ADDRESSING, ILC_LATER);
+        return 1;
+    }
 
-    tlb_set_page(env, address & TARGET_PAGE_MASK,
-                 phys & TARGET_PAGE_MASK, prot,
+    DPRINTF("%s: set tlb %" PRIx64 " -> %" PRIx64 " (%x)\n", __FUNCTION__,
+            (uint64_t)vaddr, (uint64_t)raddr, prot);
+
+    tlb_set_page(env, _vaddr, raddr, prot,
                  mmu_idx, TARGET_PAGE_SIZE);
+
     return 0;
 }
-#endif /* CONFIG_USER_ONLY */
+
+target_phys_addr_t cpu_get_phys_page_debug(CPUState *env, target_ulong vaddr)
+{
+    target_ulong raddr;
+    int prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
+    int old_exc = env->exception_index;
+    uint64_t asc = env->psw.mask & PSW_MASK_ASC;
+
+    /* 31-Bit mode */
+    if (!(env->psw.mask & PSW_MASK_64)) {
+        vaddr &= 0x7fffffff;
+    }
+
+    mmu_translate(env, vaddr, 2, asc, &raddr, &prot);
+    env->exception_index = old_exc;
+
+    return raddr;
+}
+
+void load_psw(CPUState *env, uint64_t mask, uint64_t addr)
+{
+    if (mask & PSW_MASK_WAIT) {
+        env->halted = 1;
+        env->exception_index = EXCP_HLT;
+        if (!(mask & (PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK))) {
+            /* XXX disabled wait state - CPU is dead */
+        }
+    }
+
+    env->psw.addr = addr;
+    env->psw.mask = mask;
+    env->cc_op = (mask >> 13) & 3;
+}
+
+static uint64_t get_psw_mask(CPUState *env)
+{
+    uint64_t r = env->psw.mask;
+
+    env->cc_op = calc_cc(env, env->cc_op, env->cc_src, env->cc_dst, env->cc_vr);
+
+    r &= ~(3ULL << 13);
+    assert(!(env->cc_op & ~3));
+    r |= env->cc_op << 13;
+
+    return r;
+}
+
+static void do_svc_interrupt(CPUState *env)
+{
+    uint64_t mask, addr;
+    LowCore *lowcore;
+    target_phys_addr_t len = TARGET_PAGE_SIZE;
+
+    lowcore = cpu_physical_memory_map(env->psa, &len, 1);
+
+    lowcore->svc_code = cpu_to_be16(env->int_svc_code);
+    lowcore->svc_ilc = cpu_to_be16(env->int_svc_ilc);
+    lowcore->svc_old_psw.mask = cpu_to_be64(get_psw_mask(env));
+    lowcore->svc_old_psw.addr = cpu_to_be64(env->psw.addr + (env->int_svc_ilc));
+    mask = be64_to_cpu(lowcore->svc_new_psw.mask);
+    addr = be64_to_cpu(lowcore->svc_new_psw.addr);
+
+    cpu_physical_memory_unmap(lowcore, len, 1, len);
+
+    load_psw(env, mask, addr);
+}
+
+static void do_program_interrupt(CPUState *env)
+{
+    uint64_t mask, addr;
+    LowCore *lowcore;
+    target_phys_addr_t len = TARGET_PAGE_SIZE;
+    int ilc = env->int_pgm_ilc;
+
+    switch (ilc) {
+    case ILC_LATER:
+        ilc = get_ilc(ldub_code(env->psw.addr));
+        break;
+    case ILC_LATER_INC:
+        ilc = get_ilc(ldub_code(env->psw.addr));
+        env->psw.addr += ilc * 2;
+        break;
+    case ILC_LATER_INC_2:
+        ilc = get_ilc(ldub_code(env->psw.addr)) * 2;
+        env->psw.addr += ilc;
+        break;
+    }
+
+    qemu_log("%s: code=0x%x ilc=%d\n", __FUNCTION__, env->int_pgm_code, ilc);
+
+    lowcore = cpu_physical_memory_map(env->psa, &len, 1);
+
+    lowcore->pgm_ilc = cpu_to_be16(ilc);
+    lowcore->pgm_code = cpu_to_be16(env->int_pgm_code);
+    lowcore->program_old_psw.mask = cpu_to_be64(get_psw_mask(env));
+    lowcore->program_old_psw.addr = cpu_to_be64(env->psw.addr);
+    mask = be64_to_cpu(lowcore->program_new_psw.mask);
+    addr = be64_to_cpu(lowcore->program_new_psw.addr);
+
+    cpu_physical_memory_unmap(lowcore, len, 1, len);
+
+    DPRINTF("%s: %x %x %" PRIx64 " %" PRIx64 "\n", __FUNCTION__,
+            env->int_pgm_code, ilc, env->psw.mask,
+            env->psw.addr);
+
+    load_psw(env, mask, addr);
+}
+
+#define VIRTIO_SUBCODE_64 0x0D00
+
+static void do_ext_interrupt(CPUState *env)
+{
+    uint64_t mask, addr;
+    LowCore *lowcore;
+    target_phys_addr_t len = TARGET_PAGE_SIZE;
+    ExtQueue *q;
+
+    if (!(env->psw.mask & PSW_MASK_EXT)) {
+        cpu_abort(env, "Ext int w/o ext mask\n");
+    }
+
+    if (env->ext_index < 0 || env->ext_index > MAX_EXT_QUEUE) {
+        cpu_abort(env, "Ext queue overrun: %d\n", env->ext_index);
+    }
+
+    q = &env->ext_queue[env->ext_index];
+    lowcore = cpu_physical_memory_map(env->psa, &len, 1);
+
+    lowcore->ext_int_code = cpu_to_be16(q->code);
+    lowcore->ext_params = cpu_to_be32(q->param);
+    lowcore->ext_params2 = cpu_to_be64(q->param64);
+    lowcore->external_old_psw.mask = cpu_to_be64(get_psw_mask(env));
+    lowcore->external_old_psw.addr = cpu_to_be64(env->psw.addr);
+    lowcore->cpu_addr = cpu_to_be16(env->cpu_num | VIRTIO_SUBCODE_64);
+    mask = be64_to_cpu(lowcore->external_new_psw.mask);
+    addr = be64_to_cpu(lowcore->external_new_psw.addr);
+
+    cpu_physical_memory_unmap(lowcore, len, 1, len);
+
+    env->ext_index--;
+    if (env->ext_index == -1) {
+        env->pending_int &= ~INTERRUPT_EXT;
+    }
+
+    DPRINTF("%s: %" PRIx64 " %" PRIx64 "\n", __FUNCTION__,
+            env->psw.mask, env->psw.addr);
+
+    load_psw(env, mask, addr);
+}
 
 void do_interrupt (CPUState *env)
 {
+    qemu_log("%s: %d at pc=%" PRIx64 "\n", __FUNCTION__, env->exception_index,
+             env->psw.addr);
+
+    /* handle external interrupts */
+    if ((env->psw.mask & PSW_MASK_EXT) &&
+        env->exception_index == -1) {
+        if (env->pending_int & INTERRUPT_EXT) {
+            /* code is already in env */
+            env->exception_index = EXCP_EXT;
+        } else if (env->pending_int & INTERRUPT_TOD) {
+            cpu_inject_ext(env, 0x1004, 0, 0);
+            env->exception_index = EXCP_EXT;
+            env->pending_int &= ~INTERRUPT_EXT;
+            env->pending_int &= ~INTERRUPT_TOD;
+        } else if (env->pending_int & INTERRUPT_CPUTIMER) {
+            cpu_inject_ext(env, 0x1005, 0, 0);
+            env->exception_index = EXCP_EXT;
+            env->pending_int &= ~INTERRUPT_EXT;
+            env->pending_int &= ~INTERRUPT_TOD;
+        }
+    }
+
+    switch (env->exception_index) {
+    case EXCP_PGM:
+        do_program_interrupt(env);
+        break;
+    case EXCP_SVC:
+        do_svc_interrupt(env);
+        break;
+    case EXCP_EXT:
+        do_ext_interrupt(env);
+        break;
+    }
+    env->exception_index = -1;
+
+    if (!env->pending_int) {
+        env->interrupt_request &= ~CPU_INTERRUPT_HARD;
+    }
 }
+
+#endif /* CONFIG_USER_ONLY */
diff --git a/target-s390x/op_helper.c b/target-s390x/op_helper.c
index be455b9..7f0adcb 100644
--- a/target-s390x/op_helper.c
+++ b/target-s390x/op_helper.c
@@ -71,3 +71,9 @@ void tlb_fill (target_ulong addr, int is_write, int mmu_idx, void *retaddr)
 }
 
 #endif
+
+uint32_t calc_cc(CPUState *env, uint32_t cc_op, uint64_t src, uint64_t dst,
+                 uint64_t vr)
+{
+    return 0;
+}
diff --git a/target-s390x/translate.c b/target-s390x/translate.c
index 4d45e32..f995384 100644
--- a/target-s390x/translate.c
+++ b/target-s390x/translate.c
@@ -46,6 +46,10 @@ void cpu_dump_state(CPUState *env, FILE *f, fprintf_function cpu_fprintf,
     cpu_fprintf(f, "PSW=mask %016lx addr %016lx cc %02x\n", env->psw.mask, env->psw.addr, env->cc);
 }
 
+void s390x_translate_init(void)
+{
+}
+
 void gen_intermediate_code (CPUState *env, struct TranslationBlock *tb)
 {
 }