aboutsummaryrefslogtreecommitdiff
path: root/cpu-exec.c
blob: 94fedc5805bd61086e6b7b772283bf5f02bd4c91 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
/*
 *  emulator main execution loop
 *
 *  Copyright (c) 2003-2005 Fabrice Bellard
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */
#include "config.h"
#include "cpu.h"
#include "disas/disas.h"
#include "tcg.h"
#include "qemu/atomic.h"
#include "sysemu/qtest.h"

//#define CONFIG_DEBUG_EXEC

bool qemu_cpu_has_work(CPUState *cpu)
{
    return cpu_has_work(cpu);
}

void cpu_loop_exit(CPUArchState *env)
{
    CPUState *cpu = ENV_GET_CPU(env);

    cpu->current_tb = NULL;
    siglongjmp(env->jmp_env, 1);
}

/* exit the current TB from a signal handler. The host registers are
   restored in a state compatible with the CPU emulator
 */
#if defined(CONFIG_SOFTMMU)
void cpu_resume_from_signal(CPUArchState *env, void *puc)
{
    /* XXX: restore cpu registers saved in host registers */

    env->exception_index = -1;
    siglongjmp(env->jmp_env, 1);
}
#endif

/* Execute a TB, and fix up the CPU state afterwards if necessary */
static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, uint8_t *tb_ptr)
{
    CPUArchState *env = cpu->env_ptr;
    tcg_target_ulong next_tb = tcg_qemu_tb_exec(env, tb_ptr);
    if ((next_tb & TB_EXIT_MASK) > TB_EXIT_IDX1) {
        /* We didn't start executing this TB (eg because the instruction
         * counter hit zero); we must restore the guest PC to the address
         * of the start of the TB.
         */
        TranslationBlock *tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
        cpu_pc_from_tb(env, tb);
    }
    if ((next_tb & TB_EXIT_MASK) == TB_EXIT_REQUESTED) {
        /* We were asked to stop executing TBs (probably a pending
         * interrupt. We've now stopped, so clear the flag.
         */
        cpu->tcg_exit_req = 0;
    }
    return next_tb;
}

/* Execute the code without caching the generated code. An interpreter
   could be used if available. */
static void cpu_exec_nocache(CPUArchState *env, int max_cycles,
                             TranslationBlock *orig_tb)
{
    CPUState *cpu = ENV_GET_CPU(env);
    TranslationBlock *tb;

    /* Should never happen.
       We only end up here when an existing TB is too long.  */
    if (max_cycles > CF_COUNT_MASK)
        max_cycles = CF_COUNT_MASK;

    tb = tb_gen_code(env, orig_tb->pc, orig_tb->cs_base, orig_tb->flags,
                     max_cycles);
    cpu->current_tb = tb;
    /* execute the generated code */
    cpu_tb_exec(cpu, tb->tc_ptr);
    cpu->current_tb = NULL;
    tb_phys_invalidate(tb, -1);
    tb_free(tb);
}

static TranslationBlock *tb_find_slow(CPUArchState *env,
                                      target_ulong pc,
                                      target_ulong cs_base,
                                      uint64_t flags)
{
    TranslationBlock *tb, **ptb1;
    unsigned int h;
    tb_page_addr_t phys_pc, phys_page1;
    target_ulong virt_page2;

    tcg_ctx.tb_ctx.tb_invalidated_flag = 0;

    /* find translated block using physical mappings */
    phys_pc = get_page_addr_code(env, pc);
    phys_page1 = phys_pc & TARGET_PAGE_MASK;
    h = tb_phys_hash_func(phys_pc);
    ptb1 = &tcg_ctx.tb_ctx.tb_phys_hash[h];
    for(;;) {
        tb = *ptb1;
        if (!tb)
            goto not_found;
        if (tb->pc == pc &&
            tb->page_addr[0] == phys_page1 &&
            tb->cs_base == cs_base &&
            tb->flags == flags) {
            /* check next page if needed */
            if (tb->page_addr[1] != -1) {
                tb_page_addr_t phys_page2;

                virt_page2 = (pc & TARGET_PAGE_MASK) +
                    TARGET_PAGE_SIZE;
                phys_page2 = get_page_addr_code(env, virt_page2);
                if (tb->page_addr[1] == phys_page2)
                    goto found;
            } else {
                goto found;
            }
        }
        ptb1 = &tb->phys_hash_next;
    }
 not_found:
   /* if no translated code available, then translate it now */
    tb = tb_gen_code(env, pc, cs_base, flags, 0);

 found:
    /* Move the last found TB to the head of the list */
    if (likely(*ptb1)) {
        *ptb1 = tb->phys_hash_next;
        tb->phys_hash_next = tcg_ctx.tb_ctx.tb_phys_hash[h];
        tcg_ctx.tb_ctx.tb_phys_hash[h] = tb;
    }
    /* we add the TB in the virtual pc hash table */
    env->tb_jmp_cache[tb_jmp_cache_hash_func(pc)] = tb;
    return tb;
}

static inline TranslationBlock *tb_find_fast(CPUArchState *env)
{
    TranslationBlock *tb;
    target_ulong cs_base, pc;
    int flags;

    /* we record a subset of the CPU state. It will
       always be the same before a given translated block
       is executed. */
    cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
    tb = env->tb_jmp_cache[tb_jmp_cache_hash_func(pc)];
    if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base ||
                 tb->flags != flags)) {
        tb = tb_find_slow(env, pc, cs_base, flags);
    }
    return tb;
}

static CPUDebugExcpHandler *debug_excp_handler;

void cpu_set_debug_excp_handler(CPUDebugExcpHandler *handler)
{
    debug_excp_handler = handler;
}

static void cpu_handle_debug_exception(CPUArchState *env)
{
    CPUWatchpoint *wp;

    if (!env->watchpoint_hit) {
        QTAILQ_FOREACH(wp, &env->watchpoints, entry) {
            wp->flags &= ~BP_WATCHPOINT_HIT;
        }
    }
    if (debug_excp_handler) {
        debug_excp_handler(env);
    }
}

/* main execution loop */

volatile sig_atomic_t exit_request;

int cpu_exec(CPUArchState *env)
{
    CPUState *cpu = ENV_GET_CPU(env);
#if !(defined(CONFIG_USER_ONLY) && \
      (defined(TARGET_M68K) || defined(TARGET_PPC) || defined(TARGET_S390X)))
    CPUClass *cc = CPU_GET_CLASS(cpu);
#endif
    int ret, interrupt_request;
    TranslationBlock *tb;
    uint8_t *tc_ptr;
    tcg_target_ulong next_tb;

    if (cpu->halted) {
        if (!cpu_has_work(cpu)) {
            return EXCP_HALTED;
        }

        cpu->halted = 0;
    }

    cpu_single_env = env;

    if (unlikely(exit_request)) {
        cpu->exit_request = 1;
    }

#if defined(TARGET_I386)
    /* put eflags in CPU temporary format */
    CC_SRC = env->eflags & (CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
    DF = 1 - (2 * ((env->eflags >> 10) & 1));
    CC_OP = CC_OP_EFLAGS;
    env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
#elif defined(TARGET_SPARC)
#elif defined(TARGET_M68K)
    env->cc_op = CC_OP_FLAGS;
    env->cc_dest = env->sr & 0xf;
    env->cc_x = (env->sr >> 4) & 1;
#elif defined(TARGET_ALPHA)
#elif defined(TARGET_ARM)
#elif defined(TARGET_UNICORE32)
#elif defined(TARGET_PPC)
    env->reserve_addr = -1;
#elif defined(TARGET_LM32)
#elif defined(TARGET_MICROBLAZE)
#elif defined(TARGET_MIPS)
#elif defined(TARGET_OPENRISC)
#elif defined(TARGET_SH4)
#elif defined(TARGET_CRIS)
#elif defined(TARGET_S390X)
#elif defined(TARGET_XTENSA)
    /* XXXXX */
#else
#error unsupported target CPU
#endif
    env->exception_index = -1;

    /* prepare setjmp context for exception handling */
    for(;;) {
        if (sigsetjmp(env->jmp_env, 0) == 0) {
            /* if an exception is pending, we execute it here */
            if (env->exception_index >= 0) {
                if (env->exception_index >= EXCP_INTERRUPT) {
                    /* exit request from the cpu execution loop */
                    ret = env->exception_index;
                    if (ret == EXCP_DEBUG) {
                        cpu_handle_debug_exception(env);
                    }
                    break;
                } else {
#if defined(CONFIG_USER_ONLY)
                    /* if user mode only, we simulate a fake exception
                       which will be handled outside the cpu execution
                       loop */
#if defined(TARGET_I386)
                    cc->do_interrupt(cpu);
#endif
                    ret = env->exception_index;
                    break;
#else
                    cc->do_interrupt(cpu);
                    env->exception_index = -1;
#endif
                }
            }

            next_tb = 0; /* force lookup of first TB */
            for(;;) {
                interrupt_request = cpu->interrupt_request;
                if (unlikely(interrupt_request)) {
                    if (unlikely(env->singlestep_enabled & SSTEP_NOIRQ)) {
                        /* Mask out external interrupts for this step. */
                        interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK;
                    }
                    if (interrupt_request & CPU_INTERRUPT_DEBUG) {
                        cpu->interrupt_request &= ~CPU_INTERRUPT_DEBUG;
                        env->exception_index = EXCP_DEBUG;
                        cpu_loop_exit(env);
                    }
#if defined(TARGET_ARM) || defined(TARGET_SPARC) || defined(TARGET_MIPS) || \
    defined(TARGET_PPC) || defined(TARGET_ALPHA) || defined(TARGET_CRIS) || \
    defined(TARGET_MICROBLAZE) || defined(TARGET_LM32) || defined(TARGET_UNICORE32)
                    if (interrupt_request & CPU_INTERRUPT_HALT) {
                        cpu->interrupt_request &= ~CPU_INTERRUPT_HALT;
                        cpu->halted = 1;
                        env->exception_index = EXCP_HLT;
                        cpu_loop_exit(env);
                    }
#endif
#if defined(TARGET_I386)
#if !defined(CONFIG_USER_ONLY)
                    if (interrupt_request & CPU_INTERRUPT_POLL) {
                        cpu->interrupt_request &= ~CPU_INTERRUPT_POLL;
                        apic_poll_irq(env->apic_state);
                    }
#endif
                    if (interrupt_request & CPU_INTERRUPT_INIT) {
                            cpu_svm_check_intercept_param(env, SVM_EXIT_INIT,
                                                          0);
                            do_cpu_init(x86_env_get_cpu(env));
                            env->exception_index = EXCP_HALTED;
                            cpu_loop_exit(env);
                    } else if (interrupt_request & CPU_INTERRUPT_SIPI) {
                            do_cpu_sipi(x86_env_get_cpu(env));
                    } else if (env->hflags2 & HF2_GIF_MASK) {
                        if ((interrupt_request & CPU_INTERRUPT_SMI) &&
                            !(env->hflags & HF_SMM_MASK)) {
                            cpu_svm_check_intercept_param(env, SVM_EXIT_SMI,
                                                          0);
                            cpu->interrupt_request &= ~CPU_INTERRUPT_SMI;
                            do_smm_enter(env);
                            next_tb = 0;
                        } else if ((interrupt_request & CPU_INTERRUPT_NMI) &&
                                   !(env->hflags2 & HF2_NMI_MASK)) {
                            cpu->interrupt_request &= ~CPU_INTERRUPT_NMI;
                            env->hflags2 |= HF2_NMI_MASK;
                            do_interrupt_x86_hardirq(env, EXCP02_NMI, 1);
                            next_tb = 0;
                        } else if (interrupt_request & CPU_INTERRUPT_MCE) {
                            cpu->interrupt_request &= ~CPU_INTERRUPT_MCE;
                            do_interrupt_x86_hardirq(env, EXCP12_MCHK, 0);
                            next_tb = 0;
                        } else if ((interrupt_request & CPU_INTERRUPT_HARD) &&
                                   (((env->hflags2 & HF2_VINTR_MASK) && 
                                     (env->hflags2 & HF2_HIF_MASK)) ||
                                    (!(env->hflags2 & HF2_VINTR_MASK) && 
                                     (env->eflags & IF_MASK && 
                                      !(env->hflags & HF_INHIBIT_IRQ_MASK))))) {
                            int intno;
                            cpu_svm_check_intercept_param(env, SVM_EXIT_INTR,
                                                          0);
                            cpu->interrupt_request &= ~(CPU_INTERRUPT_HARD |
                                                        CPU_INTERRUPT_VIRQ);
                            intno = cpu_get_pic_interrupt(env);
                            qemu_log_mask(CPU_LOG_TB_IN_ASM, "Servicing hardware INT=0x%02x\n", intno);
                            do_interrupt_x86_hardirq(env, intno, 1);
                            /* ensure that no TB jump will be modified as
                               the program flow was changed */
                            next_tb = 0;
#if !defined(CONFIG_USER_ONLY)
                        } else if ((interrupt_request & CPU_INTERRUPT_VIRQ) &&
                                   (env->eflags & IF_MASK) && 
                                   !(env->hflags & HF_INHIBIT_IRQ_MASK)) {
                            int intno;
                            /* FIXME: this should respect TPR */
                            cpu_svm_check_intercept_param(env, SVM_EXIT_VINTR,
                                                          0);
                            intno = ldl_phys(env->vm_vmcb + offsetof(struct vmcb, control.int_vector));
                            qemu_log_mask(CPU_LOG_TB_IN_ASM, "Servicing virtual hardware INT=0x%02x\n", intno);
                            do_interrupt_x86_hardirq(env, intno, 1);
                            cpu->interrupt_request &= ~CPU_INTERRUPT_VIRQ;
                            next_tb = 0;
#endif
                        }
                    }
#elif defined(TARGET_PPC)
                    if ((interrupt_request & CPU_INTERRUPT_RESET)) {
                        cpu_reset(cpu);
                    }
                    if (interrupt_request & CPU_INTERRUPT_HARD) {
                        ppc_hw_interrupt(env);
                        if (env->pending_interrupts == 0) {
                            cpu->interrupt_request &= ~CPU_INTERRUPT_HARD;
                        }
                        next_tb = 0;
                    }
#elif defined(TARGET_LM32)
                    if ((interrupt_request & CPU_INTERRUPT_HARD)
                        && (env->ie & IE_IE)) {
                        env->exception_index = EXCP_IRQ;
                        cc->do_interrupt(cpu);
                        next_tb = 0;
                    }
#elif defined(TARGET_MICROBLAZE)
                    if ((interrupt_request & CPU_INTERRUPT_HARD)
                        && (env->sregs[SR_MSR] & MSR_IE)
                        && !(env->sregs[SR_MSR] & (MSR_EIP | MSR_BIP))
                        && !(env->iflags & (D_FLAG | IMM_FLAG))) {
                        env->exception_index = EXCP_IRQ;
                        cc->do_interrupt(cpu);
                        next_tb = 0;
                    }
#elif defined(TARGET_MIPS)
                    if ((interrupt_request & CPU_INTERRUPT_HARD) &&
                        cpu_mips_hw_interrupts_pending(env)) {
                        /* Raise it */
                        env->exception_index = EXCP_EXT_INTERRUPT;
                        env->error_code = 0;
                        cc->do_interrupt(cpu);
                        next_tb = 0;
                    }
#elif defined(TARGET_OPENRISC)
                    {
                        int idx = -1;
                        if ((interrupt_request & CPU_INTERRUPT_HARD)
                            && (env->sr & SR_IEE)) {
                            idx = EXCP_INT;
                        }
                        if ((interrupt_request & CPU_INTERRUPT_TIMER)
                            && (env->sr & SR_TEE)) {
                            idx = EXCP_TICK;
                        }
                        if (idx >= 0) {
                            env->exception_index = idx;
                            cc->do_interrupt(cpu);
                            next_tb = 0;
                        }
                    }
#elif defined(TARGET_SPARC)
                    if (interrupt_request & CPU_INTERRUPT_HARD) {
                        if (cpu_interrupts_enabled(env) &&
                            env->interrupt_index > 0) {
                            int pil = env->interrupt_index & 0xf;
                            int type = env->interrupt_index & 0xf0;

                            if (((type == TT_EXTINT) &&
                                  cpu_pil_allowed(env, pil)) ||
                                  type != TT_EXTINT) {
                                env->exception_index = env->interrupt_index;
                                cc->do_interrupt(cpu);
                                next_tb = 0;
                            }
                        }
                    }
#elif defined(TARGET_ARM)
                    if (interrupt_request & CPU_INTERRUPT_FIQ
                        && !(env->uncached_cpsr & CPSR_F)) {
                        env->exception_index = EXCP_FIQ;
                        cc->do_interrupt(cpu);
                        next_tb = 0;
                    }
                    /* ARMv7-M interrupt return works by loading a magic value
                       into the PC.  On real hardware the load causes the
                       return to occur.  The qemu implementation performs the
                       jump normally, then does the exception return when the
                       CPU tries to execute code at the magic address.
                       This will cause the magic PC value to be pushed to
                       the stack if an interrupt occurred at the wrong time.
                       We avoid this by disabling interrupts when
                       pc contains a magic address.  */
                    if (interrupt_request & CPU_INTERRUPT_HARD
                        && ((IS_M(env) && env->regs[15] < 0xfffffff0)
                            || !(env->uncached_cpsr & CPSR_I))) {
                        env->exception_index = EXCP_IRQ;
                        cc->do_interrupt(cpu);
                        next_tb = 0;
                    }
#elif defined(TARGET_UNICORE32)
                    if (interrupt_request & CPU_INTERRUPT_HARD
                        && !(env->uncached_asr & ASR_I)) {
                        env->exception_index = UC32_EXCP_INTR;
                        cc->do_interrupt(cpu);
                        next_tb = 0;
                    }
#elif defined(TARGET_SH4)
                    if (interrupt_request & CPU_INTERRUPT_HARD) {
                        cc->do_interrupt(cpu);
                        next_tb = 0;
                    }
#elif defined(TARGET_ALPHA)
                    {
                        int idx = -1;
                        /* ??? This hard-codes the OSF/1 interrupt levels.  */
                        switch (env->pal_mode ? 7 : env->ps & PS_INT_MASK) {
                        case 0 ... 3:
                            if (interrupt_request & CPU_INTERRUPT_HARD) {
                                idx = EXCP_DEV_INTERRUPT;
                            }
                            /* FALLTHRU */
                        case 4:
                            if (interrupt_request & CPU_INTERRUPT_TIMER) {
                                idx = EXCP_CLK_INTERRUPT;
                            }
                            /* FALLTHRU */
                        case 5:
                            if (interrupt_request & CPU_INTERRUPT_SMP) {
                                idx = EXCP_SMP_INTERRUPT;
                            }
                            /* FALLTHRU */
                        case 6:
                            if (interrupt_request & CPU_INTERRUPT_MCHK) {
                                idx = EXCP_MCHK;
                            }
                        }
                        if (idx >= 0) {
                            env->exception_index = idx;
                            env->error_code = 0;
                            cc->do_interrupt(cpu);
                            next_tb = 0;
                        }
                    }
#elif defined(TARGET_CRIS)
                    if (interrupt_request & CPU_INTERRUPT_HARD
                        && (env->pregs[PR_CCS] & I_FLAG)
                        && !env->locked_irq) {
                        env->exception_index = EXCP_IRQ;
                        cc->do_interrupt(cpu);
                        next_tb = 0;
                    }
                    if (interrupt_request & CPU_INTERRUPT_NMI) {
                        unsigned int m_flag_archval;
                        if (env->pregs[PR_VR] < 32) {
                            m_flag_archval = M_FLAG_V10;
                        } else {
                            m_flag_archval = M_FLAG_V32;
                        }
                        if ((env->pregs[PR_CCS] & m_flag_archval)) {
                            env->exception_index = EXCP_NMI;
                            cc->do_interrupt(cpu);
                            next_tb = 0;
                        }
                    }
#elif defined(TARGET_M68K)
                    if (interrupt_request & CPU_INTERRUPT_HARD
                        && ((env->sr & SR_I) >> SR_I_SHIFT)
                            < env->pending_level) {
                        /* Real hardware gets the interrupt vector via an
                           IACK cycle at this point.  Current emulated
                           hardware doesn't rely on this, so we
                           provide/save the vector when the interrupt is
                           first signalled.  */
                        env->exception_index = env->pending_vector;
                        do_interrupt_m68k_hardirq(env);
                        next_tb = 0;
                    }
#elif defined(TARGET_S390X) && !defined(CONFIG_USER_ONLY)
                    if ((interrupt_request & CPU_INTERRUPT_HARD) &&
                        (env->psw.mask & PSW_MASK_EXT)) {
                        cc->do_interrupt(cpu);
                        next_tb = 0;
                    }
#elif defined(TARGET_XTENSA)
                    if (interrupt_request & CPU_INTERRUPT_HARD) {
                        env->exception_index = EXC_IRQ;
                        cc->do_interrupt(cpu);
                        next_tb = 0;
                    }
#endif
                   /* Don't use the cached interrupt_request value,
                      do_interrupt may have updated the EXITTB flag. */
                    if (cpu->interrupt_request & CPU_INTERRUPT_EXITTB) {
                        cpu->interrupt_request &= ~CPU_INTERRUPT_EXITTB;
                        /* ensure that no TB jump will be modified as
                           the program flow was changed */
                        next_tb = 0;
                    }
                }
                if (unlikely(cpu->exit_request)) {
                    cpu->exit_request = 0;
                    env->exception_index = EXCP_INTERRUPT;
                    cpu_loop_exit(env);
                }
#if defined(DEBUG_DISAS) || defined(CONFIG_DEBUG_EXEC)
                if (qemu_loglevel_mask(CPU_LOG_TB_CPU)) {
                    /* restore flags in standard format */
#if defined(TARGET_I386)
                    env->eflags = env->eflags | cpu_cc_compute_all(env, CC_OP)
                        | (DF & DF_MASK);
                    log_cpu_state(env, CPU_DUMP_CCOP);
                    env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
#elif defined(TARGET_M68K)
                    cpu_m68k_flush_flags(env, env->cc_op);
                    env->cc_op = CC_OP_FLAGS;
                    env->sr = (env->sr & 0xffe0)
                              | env->cc_dest | (env->cc_x << 4);
                    log_cpu_state(env, 0);
#else
                    log_cpu_state(env, 0);
#endif
                }
#endif /* DEBUG_DISAS || CONFIG_DEBUG_EXEC */
                spin_lock(&tcg_ctx.tb_ctx.tb_lock);
                tb = tb_find_fast(env);
                /* Note: we do it here to avoid a gcc bug on Mac OS X when
                   doing it in tb_find_slow */
                if (tcg_ctx.tb_ctx.tb_invalidated_flag) {
                    /* as some TB could have been invalidated because
                       of memory exceptions while generating the code, we
                       must recompute the hash index here */
                    next_tb = 0;
                    tcg_ctx.tb_ctx.tb_invalidated_flag = 0;
                }
#ifdef CONFIG_DEBUG_EXEC
                qemu_log_mask(CPU_LOG_EXEC, "Trace %p [" TARGET_FMT_lx "] %s\n",
                             tb->tc_ptr, tb->pc,
                             lookup_symbol(tb->pc));
#endif
                /* see if we can patch the calling TB. When the TB
                   spans two pages, we cannot safely do a direct
                   jump. */
                if (next_tb != 0 && tb->page_addr[1] == -1) {
                    tb_add_jump((TranslationBlock *)(next_tb & ~TB_EXIT_MASK),
                                next_tb & TB_EXIT_MASK, tb);
                }
                spin_unlock(&tcg_ctx.tb_ctx.tb_lock);

                /* cpu_interrupt might be called while translating the
                   TB, but before it is linked into a potentially
                   infinite loop and becomes env->current_tb. Avoid
                   starting execution if there is a pending interrupt. */
                cpu->current_tb = tb;
                barrier();
                if (likely(!cpu->exit_request)) {
                    tc_ptr = tb->tc_ptr;
                    /* execute the generated code */
                    next_tb = cpu_tb_exec(cpu, tc_ptr);
                    switch (next_tb & TB_EXIT_MASK) {
                    case TB_EXIT_REQUESTED:
                        /* Something asked us to stop executing
                         * chained TBs; just continue round the main
                         * loop. Whatever requested the exit will also
                         * have set something else (eg exit_request or
                         * interrupt_request) which we will handle
                         * next time around the loop.
                         */
                        tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
                        next_tb = 0;
                        break;
                    case TB_EXIT_ICOUNT_EXPIRED:
                    {
                        /* Instruction counter expired.  */
                        int insns_left;
                        tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
                        insns_left = env->icount_decr.u32;
                        if (env->icount_extra && insns_left >= 0) {
                            /* Refill decrementer and continue execution.  */
                            env->icount_extra += insns_left;
                            if (env->icount_extra > 0xffff) {
                                insns_left = 0xffff;
                            } else {
                                insns_left = env->icount_extra;
                            }
                            env->icount_extra -= insns_left;
                            env->icount_decr.u16.low = insns_left;
                        } else {
                            if (insns_left > 0) {
                                /* Execute remaining instructions.  */
                                cpu_exec_nocache(env, insns_left, tb);
                            }
                            env->exception_index = EXCP_INTERRUPT;
                            next_tb = 0;
                            cpu_loop_exit(env);
                        }
                        break;
                    }
                    default:
                        break;
                    }
                }
                cpu->current_tb = NULL;
                /* reset soft MMU for next block (it can currently
                   only be set by a memory fault) */
            } /* for(;;) */
        } else {
            /* Reload env after longjmp - the compiler may have smashed all
             * local variables as longjmp is marked 'noreturn'. */
            env = cpu_single_env;
        }
    } /* for(;;) */


#if defined(TARGET_I386)
    /* restore flags in standard format */
    env->eflags = env->eflags | cpu_cc_compute_all(env, CC_OP)
        | (DF & DF_MASK);
#elif defined(TARGET_ARM)
    /* XXX: Save/restore host fpu exception state?.  */
#elif defined(TARGET_UNICORE32)
#elif defined(TARGET_SPARC)
#elif defined(TARGET_PPC)
#elif defined(TARGET_LM32)
#elif defined(TARGET_M68K)
    cpu_m68k_flush_flags(env, env->cc_op);
    env->cc_op = CC_OP_FLAGS;
    env->sr = (env->sr & 0xffe0)
              | env->cc_dest | (env->cc_x << 4);
#elif defined(TARGET_MICROBLAZE)
#elif defined(TARGET_MIPS)
#elif defined(TARGET_OPENRISC)
#elif defined(TARGET_SH4)
#elif defined(TARGET_ALPHA)
#elif defined(TARGET_CRIS)
#elif defined(TARGET_S390X)
#elif defined(TARGET_XTENSA)
    /* XXXXX */
#else
#error unsupported target CPU
#endif

    /* fail safe : never use cpu_single_env outside cpu_exec() */
    cpu_single_env = NULL;
    return ret;
}