cpu-exec.c

   1 /*
   2  *  emulator main execution loop
   3  *
   4  *  Copyright (c) 2003-2005 Fabrice Bellard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19 #include "config.h"
  20 #include "cpu.h"
  21 #include "disas/disas.h"
  22 #include "tcg.h"
  23 #include "qemu/atomic.h"
  24 #include "sysemu/qtest.h"
  25
  26 int tb_invalidated_flag;
  27
  28 //#define CONFIG_DEBUG_EXEC
  29
  30 bool qemu_cpu_has_work(CPUState *cpu)
  31 {
  32     return cpu_has_work(cpu);
  33 }
  34
  35 void cpu_loop_exit(CPUArchState *env)
  36 {
  37     env->current_tb = NULL;
  38     longjmp(env->jmp_env, 1);
  39 }
  40
  41 /* exit the current TB from a signal handler. The host registers are
  42    restored in a state compatible with the CPU emulator
  43  */
  44 #if defined(CONFIG_SOFTMMU)
  45 void cpu_resume_from_signal(CPUArchState *env, void *puc)
  46 {
  47     /* XXX: restore cpu registers saved in host registers */
  48
  49     env->exception_index = -1;
  50     longjmp(env->jmp_env, 1);
  51 }
  52 #endif
  53
  54 /* Execute the code without caching the generated code. An interpreter
  55    could be used if available. */
  56 static void cpu_exec_nocache(CPUArchState *env, int max_cycles,
  57                              TranslationBlock *orig_tb)
  58 {
  59     tcg_target_ulong next_tb;
  60     TranslationBlock *tb;
  61
  62     /* Should never happen.
  63        We only end up here when an existing TB is too long.  */
  64     if (max_cycles > CF_COUNT_MASK)
  65         max_cycles = CF_COUNT_MASK;
  66
  67     tb = tb_gen_code(env, orig_tb->pc, orig_tb->cs_base, orig_tb->flags,
  68                      max_cycles);
  69     env->current_tb = tb;
  70     /* execute the generated code */
  71     next_tb = tcg_qemu_tb_exec(env, tb->tc_ptr);
  72     env->current_tb = NULL;
  73
  74     if ((next_tb & 3) == 2) {
  75         /* Restore PC.  This may happen if async event occurs before
  76            the TB starts executing.  */
  77         cpu_pc_from_tb(env, tb);
  78     }
  79     tb_phys_invalidate(tb, -1);
  80     tb_free(tb);
  81 }
  82
  83 static TranslationBlock *tb_find_slow(CPUArchState *env,
  84                                       target_ulong pc,
  85                                       target_ulong cs_base,
  86                                       uint64_t flags)
  87 {
  88     TranslationBlock *tb, **ptb1;
  89     unsigned int h;
  90     tb_page_addr_t phys_pc, phys_page1;
  91     target_ulong virt_page2;
  92
  93     tb_invalidated_flag = 0;
  94
  95     /* find translated block using physical mappings */
  96     phys_pc = get_page_addr_code(env, pc);
  97     phys_page1 = phys_pc & TARGET_PAGE_MASK;
  98     h = tb_phys_hash_func(phys_pc);
  99     ptb1 = &tb_phys_hash[h];
 100     for(;;) {
 101         tb = *ptb1;
 102         if (!tb)
 103             goto not_found;
 104         if (tb->pc == pc &&
 105             tb->page_addr[0] == phys_page1 &&
 106             tb->cs_base == cs_base &&
 107             tb->flags == flags) {
 108             /* check next page if needed */
 109             if (tb->page_addr[1] != -1) {
 110                 tb_page_addr_t phys_page2;
 111
 112                 virt_page2 = (pc & TARGET_PAGE_MASK) +
 113                     TARGET_PAGE_SIZE;
 114                 phys_page2 = get_page_addr_code(env, virt_page2);
 115                 if (tb->page_addr[1] == phys_page2)
 116                     goto found;
 117             } else {
 118                 goto found;
 119             }
 120         }
 121         ptb1 = &tb->phys_hash_next;
 122     }
 123  not_found:
 124    /* if no translated code available, then translate it now */
 125     tb = tb_gen_code(env, pc, cs_base, flags, 0);
 126
 127  found:
 128     /* Move the last found TB to the head of the list */
 129     if (likely(*ptb1)) {
 130         *ptb1 = tb->phys_hash_next;
 131         tb->phys_hash_next = tb_phys_hash[h];
 132         tb_phys_hash[h] = tb;
 133     }
 134     /* we add the TB in the virtual pc hash table */
 135     env->tb_jmp_cache[tb_jmp_cache_hash_func(pc)] = tb;
 136     return tb;
 137 }
 138
 139 static inline TranslationBlock *tb_find_fast(CPUArchState *env)
 140 {
 141     TranslationBlock *tb;
 142     target_ulong cs_base, pc;
 143     int flags;
 144
 145     /* we record a subset of the CPU state. It will
 146        always be the same before a given translated block
 147        is executed. */
 148     cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
 149     tb = env->tb_jmp_cache[tb_jmp_cache_hash_func(pc)];
 150     if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base ||
 151                  tb->flags != flags)) {
 152         tb = tb_find_slow(env, pc, cs_base, flags);
 153     }
 154     return tb;
 155 }
 156
 157 static CPUDebugExcpHandler *debug_excp_handler;
 158
 159 void cpu_set_debug_excp_handler(CPUDebugExcpHandler *handler)
 160 {
 161     debug_excp_handler = handler;
 162 }
 163
 164 static void cpu_handle_debug_exception(CPUArchState *env)
 165 {
 166     CPUWatchpoint *wp;
 167
 168     if (!env->watchpoint_hit) {
 169         QTAILQ_FOREACH(wp, &env->watchpoints, entry) {
 170             wp->flags &= ~BP_WATCHPOINT_HIT;
 171         }
 172     }
 173     if (debug_excp_handler) {
 174         debug_excp_handler(env);
 175     }
 176 }
 177
 178 /* main execution loop */
 179
 180 volatile sig_atomic_t exit_request;
 181
 182 int cpu_exec(CPUArchState *env)
 183 {
 184     CPUState *cpu = ENV_GET_CPU(env);
 185     int ret, interrupt_request;
 186     TranslationBlock *tb;
 187     uint8_t *tc_ptr;
 188     tcg_target_ulong next_tb;
 189
 190     if (env->halted) {
 191         if (!cpu_has_work(cpu)) {
 192             return EXCP_HALTED;
 193         }
 194
 195         env->halted = 0;
 196     }
 197
 198     cpu_single_env = env;
 199
 200     if (unlikely(exit_request)) {
 201         env->exit_request = 1;
 202     }
 203
 204 #if defined(TARGET_I386)
 205     /* put eflags in CPU temporary format */
 206     CC_SRC = env->eflags & (CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
 207     DF = 1 - (2 * ((env->eflags >> 10) & 1));
 208     CC_OP = CC_OP_EFLAGS;
 209     env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
 210 #elif defined(TARGET_SPARC)
 211 #elif defined(TARGET_M68K)
 212     env->cc_op = CC_OP_FLAGS;
 213     env->cc_dest = env->sr & 0xf;
 214     env->cc_x = (env->sr >> 4) & 1;
 215 #elif defined(TARGET_ALPHA)
 216 #elif defined(TARGET_ARM)
 217 #elif defined(TARGET_UNICORE32)
 218 #elif defined(TARGET_PPC)
 219     env->reserve_addr = -1;
 220 #elif defined(TARGET_LM32)
 221 #elif defined(TARGET_MICROBLAZE)
 222 #elif defined(TARGET_MIPS)
 223 #elif defined(TARGET_OPENRISC)
 224 #elif defined(TARGET_SH4)
 225 #elif defined(TARGET_CRIS)
 226 #elif defined(TARGET_S390X)
 227 #elif defined(TARGET_XTENSA)
 228     /* XXXXX */
 229 #else
 230 #error unsupported target CPU
 231 #endif
 232     env->exception_index = -1;
 233
 234     /* prepare setjmp context for exception handling */
 235     for(;;) {
 236         if (setjmp(env->jmp_env) == 0) {
 237             /* if an exception is pending, we execute it here */
 238             if (env->exception_index >= 0) {
 239                 if (env->exception_index >= EXCP_INTERRUPT) {
 240                     /* exit request from the cpu execution loop */
 241                     ret = env->exception_index;
 242                     if (ret == EXCP_DEBUG) {
 243                         cpu_handle_debug_exception(env);
 244                     }
 245                     break;
 246                 } else {
 247 #if defined(CONFIG_USER_ONLY)
 248                     /* if user mode only, we simulate a fake exception
 249                        which will be handled outside the cpu execution
 250                        loop */
 251 #if defined(TARGET_I386)
 252                     do_interrupt(env);
 253 #endif
 254                     ret = env->exception_index;
 255                     break;
 256 #else
 257                     do_interrupt(env);
 258                     env->exception_index = -1;
 259 #endif
 260                 }
 261             }
 262
 263             next_tb = 0; /* force lookup of first TB */
 264             for(;;) {
 265                 interrupt_request = env->interrupt_request;
 266                 if (unlikely(interrupt_request)) {
 267                     if (unlikely(env->singlestep_enabled & SSTEP_NOIRQ)) {
 268                         /* Mask out external interrupts for this step. */
 269                         interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK;
 270                     }
 271                     if (interrupt_request & CPU_INTERRUPT_DEBUG) {
 272                         env->interrupt_request &= ~CPU_INTERRUPT_DEBUG;
 273                         env->exception_index = EXCP_DEBUG;
 274                         cpu_loop_exit(env);
 275                     }
 276 #if defined(TARGET_ARM) || defined(TARGET_SPARC) || defined(TARGET_MIPS) || \
 277     defined(TARGET_PPC) || defined(TARGET_ALPHA) || defined(TARGET_CRIS) || \
 278     defined(TARGET_MICROBLAZE) || defined(TARGET_LM32) || defined(TARGET_UNICORE32)
 279                     if (interrupt_request & CPU_INTERRUPT_HALT) {
 280                         env->interrupt_request &= ~CPU_INTERRUPT_HALT;
 281                         env->halted = 1;
 282                         env->exception_index = EXCP_HLT;
 283                         cpu_loop_exit(env);
 284                     }
 285 #endif
 286 #if defined(TARGET_I386)
 287 #if !defined(CONFIG_USER_ONLY)
 288                     if (interrupt_request & CPU_INTERRUPT_POLL) {
 289                         env->interrupt_request &= ~CPU_INTERRUPT_POLL;
 290                         apic_poll_irq(env->apic_state);
 291                     }
 292 #endif
 293                     if (interrupt_request & CPU_INTERRUPT_INIT) {
 294                             cpu_svm_check_intercept_param(env, SVM_EXIT_INIT,
 295                                                           0);
 296                             do_cpu_init(x86_env_get_cpu(env));
 297                             env->exception_index = EXCP_HALTED;
 298                             cpu_loop_exit(env);
 299                     } else if (interrupt_request & CPU_INTERRUPT_SIPI) {
 300                             do_cpu_sipi(x86_env_get_cpu(env));
 301                     } else if (env->hflags2 & HF2_GIF_MASK) {
 302                         if ((interrupt_request & CPU_INTERRUPT_SMI) &&
 303                             !(env->hflags & HF_SMM_MASK)) {
 304                             cpu_svm_check_intercept_param(env, SVM_EXIT_SMI,
 305                                                           0);
 306                             env->interrupt_request &= ~CPU_INTERRUPT_SMI;
 307                             do_smm_enter(env);
 308                             next_tb = 0;
 309                         } else if ((interrupt_request & CPU_INTERRUPT_NMI) &&
 310                                    !(env->hflags2 & HF2_NMI_MASK)) {
 311                             env->interrupt_request &= ~CPU_INTERRUPT_NMI;
 312                             env->hflags2 |= HF2_NMI_MASK;
 313                             do_interrupt_x86_hardirq(env, EXCP02_NMI, 1);
 314                             next_tb = 0;
 315                         } else if (interrupt_request & CPU_INTERRUPT_MCE) {
 316                             env->interrupt_request &= ~CPU_INTERRUPT_MCE;
 317                             do_interrupt_x86_hardirq(env, EXCP12_MCHK, 0);
 318                             next_tb = 0;
 319                         } else if ((interrupt_request & CPU_INTERRUPT_HARD) &&
 320                                    (((env->hflags2 & HF2_VINTR_MASK) &&
 321                                      (env->hflags2 & HF2_HIF_MASK)) ||
 322                                     (!(env->hflags2 & HF2_VINTR_MASK) &&
 323                                      (env->eflags & IF_MASK &&
 324                                       !(env->hflags & HF_INHIBIT_IRQ_MASK))))) {
 325                             int intno;
 326                             cpu_svm_check_intercept_param(env, SVM_EXIT_INTR,
 327                                                           0);
 328                             env->interrupt_request &= ~(CPU_INTERRUPT_HARD | CPU_INTERRUPT_VIRQ);
 329                             intno = cpu_get_pic_interrupt(env);
 330                             qemu_log_mask(CPU_LOG_TB_IN_ASM, "Servicing hardware INT=0x%02x\n", intno);
 331                             do_interrupt_x86_hardirq(env, intno, 1);
 332                             /* ensure that no TB jump will be modified as
 333                                the program flow was changed */
 334                             next_tb = 0;
 335 #if !defined(CONFIG_USER_ONLY)
 336                         } else if ((interrupt_request & CPU_INTERRUPT_VIRQ) &&
 337                                    (env->eflags & IF_MASK) &&
 338                                    !(env->hflags & HF_INHIBIT_IRQ_MASK)) {
 339                             int intno;
 340                             /* FIXME: this should respect TPR */
 341                             cpu_svm_check_intercept_param(env, SVM_EXIT_VINTR,
 342                                                           0);
 343                             intno = ldl_phys(env->vm_vmcb + offsetof(struct vmcb, control.int_vector));
 344                             qemu_log_mask(CPU_LOG_TB_IN_ASM, "Servicing virtual hardware INT=0x%02x\n", intno);
 345                             do_interrupt_x86_hardirq(env, intno, 1);
 346                             env->interrupt_request &= ~CPU_INTERRUPT_VIRQ;
 347                             next_tb = 0;
 348 #endif
 349                         }
 350                     }
 351 #elif defined(TARGET_PPC)
 352                     if ((interrupt_request & CPU_INTERRUPT_RESET)) {
 353                         cpu_reset(cpu);
 354                     }
 355                     if (interrupt_request & CPU_INTERRUPT_HARD) {
 356                         ppc_hw_interrupt(env);
 357                         if (env->pending_interrupts == 0)
 358                             env->interrupt_request &= ~CPU_INTERRUPT_HARD;
 359                         next_tb = 0;
 360                     }
 361 #elif defined(TARGET_LM32)
 362                     if ((interrupt_request & CPU_INTERRUPT_HARD)
 363                         && (env->ie & IE_IE)) {
 364                         env->exception_index = EXCP_IRQ;
 365                         do_interrupt(env);
 366                         next_tb = 0;
 367                     }
 368 #elif defined(TARGET_MICROBLAZE)
 369                     if ((interrupt_request & CPU_INTERRUPT_HARD)
 370                         && (env->sregs[SR_MSR] & MSR_IE)
 371                         && !(env->sregs[SR_MSR] & (MSR_EIP | MSR_BIP))
 372                         && !(env->iflags & (D_FLAG | IMM_FLAG))) {
 373                         env->exception_index = EXCP_IRQ;
 374                         do_interrupt(env);
 375                         next_tb = 0;
 376                     }
 377 #elif defined(TARGET_MIPS)
 378                     if ((interrupt_request & CPU_INTERRUPT_HARD) &&
 379                         cpu_mips_hw_interrupts_pending(env)) {
 380                         /* Raise it */
 381                         env->exception_index = EXCP_EXT_INTERRUPT;
 382                         env->error_code = 0;
 383                         do_interrupt(env);
 384                         next_tb = 0;
 385                     }
 386 #elif defined(TARGET_OPENRISC)
 387                     {
 388                         int idx = -1;
 389                         if ((interrupt_request & CPU_INTERRUPT_HARD)
 390                             && (env->sr & SR_IEE)) {
 391                             idx = EXCP_INT;
 392                         }
 393                         if ((interrupt_request & CPU_INTERRUPT_TIMER)
 394                             && (env->sr & SR_TEE)) {
 395                             idx = EXCP_TICK;
 396                         }
 397                         if (idx >= 0) {
 398                             env->exception_index = idx;
 399                             do_interrupt(env);
 400                             next_tb = 0;
 401                         }
 402                     }
 403 #elif defined(TARGET_SPARC)
 404                     if (interrupt_request & CPU_INTERRUPT_HARD) {
 405                         if (cpu_interrupts_enabled(env) &&
 406                             env->interrupt_index > 0) {
 407                             int pil = env->interrupt_index & 0xf;
 408                             int type = env->interrupt_index & 0xf0;
 409
 410                             if (((type == TT_EXTINT) &&
 411                                   cpu_pil_allowed(env, pil)) ||
 412                                   type != TT_EXTINT) {
 413                                 env->exception_index = env->interrupt_index;
 414                                 do_interrupt(env);
 415                                 next_tb = 0;
 416                             }
 417                         }
 418                     }
 419 #elif defined(TARGET_ARM)
 420                     if (interrupt_request & CPU_INTERRUPT_FIQ
 421                         && !(env->uncached_cpsr & CPSR_F)) {
 422                         env->exception_index = EXCP_FIQ;
 423                         do_interrupt(env);
 424                         next_tb = 0;
 425                     }
 426                     /* ARMv7-M interrupt return works by loading a magic value
 427                        into the PC.  On real hardware the load causes the
 428                        return to occur.  The qemu implementation performs the
 429                        jump normally, then does the exception return when the
 430                        CPU tries to execute code at the magic address.
 431                        This will cause the magic PC value to be pushed to
 432                        the stack if an interrupt occurred at the wrong time.
 433                        We avoid this by disabling interrupts when
 434                        pc contains a magic address.  */
 435                     if (interrupt_request & CPU_INTERRUPT_HARD
 436                         && ((IS_M(env) && env->regs[15] < 0xfffffff0)
 437                             || !(env->uncached_cpsr & CPSR_I))) {
 438                         env->exception_index = EXCP_IRQ;
 439                         do_interrupt(env);
 440                         next_tb = 0;
 441                     }
 442 #elif defined(TARGET_UNICORE32)
 443                     if (interrupt_request & CPU_INTERRUPT_HARD
 444                         && !(env->uncached_asr & ASR_I)) {
 445                         env->exception_index = UC32_EXCP_INTR;
 446                         do_interrupt(env);
 447                         next_tb = 0;
 448                     }
 449 #elif defined(TARGET_SH4)
 450                     if (interrupt_request & CPU_INTERRUPT_HARD) {
 451                         do_interrupt(env);
 452                         next_tb = 0;
 453                     }
 454 #elif defined(TARGET_ALPHA)
 455                     {
 456                         int idx = -1;
 457                         /* ??? This hard-codes the OSF/1 interrupt levels.  */
 458                         switch (env->pal_mode ? 7 : env->ps & PS_INT_MASK) {
 459                         case 0 ... 3:
 460                             if (interrupt_request & CPU_INTERRUPT_HARD) {
 461                                 idx = EXCP_DEV_INTERRUPT;
 462                             }
 463                             /* FALLTHRU */
 464                         case 4:
 465                             if (interrupt_request & CPU_INTERRUPT_TIMER) {
 466                                 idx = EXCP_CLK_INTERRUPT;
 467                             }
 468                             /* FALLTHRU */
 469                         case 5:
 470                             if (interrupt_request & CPU_INTERRUPT_SMP) {
 471                                 idx = EXCP_SMP_INTERRUPT;
 472                             }
 473                             /* FALLTHRU */
 474                         case 6:
 475                             if (interrupt_request & CPU_INTERRUPT_MCHK) {
 476                                 idx = EXCP_MCHK;
 477                             }
 478                         }
 479                         if (idx >= 0) {
 480                             env->exception_index = idx;
 481                             env->error_code = 0;
 482                             do_interrupt(env);
 483                             next_tb = 0;
 484                         }
 485                     }
 486 #elif defined(TARGET_CRIS)
 487                     if (interrupt_request & CPU_INTERRUPT_HARD
 488                         && (env->pregs[PR_CCS] & I_FLAG)
 489                         && !env->locked_irq) {
 490                         env->exception_index = EXCP_IRQ;
 491                         do_interrupt(env);
 492                         next_tb = 0;
 493                     }
 494                     if (interrupt_request & CPU_INTERRUPT_NMI) {
 495                         unsigned int m_flag_archval;
 496                         if (env->pregs[PR_VR] < 32) {
 497                             m_flag_archval = M_FLAG_V10;
 498                         } else {
 499                             m_flag_archval = M_FLAG_V32;
 500                         }
 501                         if ((env->pregs[PR_CCS] & m_flag_archval)) {
 502                             env->exception_index = EXCP_NMI;
 503                             do_interrupt(env);
 504                             next_tb = 0;
 505                         }
 506                     }
 507 #elif defined(TARGET_M68K)
 508                     if (interrupt_request & CPU_INTERRUPT_HARD
 509                         && ((env->sr & SR_I) >> SR_I_SHIFT)
 510                             < env->pending_level) {
 511                         /* Real hardware gets the interrupt vector via an
 512                            IACK cycle at this point.  Current emulated
 513                            hardware doesn't rely on this, so we
 514                            provide/save the vector when the interrupt is
 515                            first signalled.  */
 516                         env->exception_index = env->pending_vector;
 517                         do_interrupt_m68k_hardirq(env);
 518                         next_tb = 0;
 519                     }
 520 #elif defined(TARGET_S390X) && !defined(CONFIG_USER_ONLY)
 521                     if ((interrupt_request & CPU_INTERRUPT_HARD) &&
 522                         (env->psw.mask & PSW_MASK_EXT)) {
 523                         do_interrupt(env);
 524                         next_tb = 0;
 525                     }
 526 #elif defined(TARGET_XTENSA)
 527                     if (interrupt_request & CPU_INTERRUPT_HARD) {
 528                         env->exception_index = EXC_IRQ;
 529                         do_interrupt(env);
 530                         next_tb = 0;
 531                     }
 532 #endif
 533                    /* Don't use the cached interrupt_request value,
 534                       do_interrupt may have updated the EXITTB flag. */
 535                     if (env->interrupt_request & CPU_INTERRUPT_EXITTB) {
 536                         env->interrupt_request &= ~CPU_INTERRUPT_EXITTB;
 537                         /* ensure that no TB jump will be modified as
 538                            the program flow was changed */
 539                         next_tb = 0;
 540                     }
 541                 }
 542                 if (unlikely(env->exit_request)) {
 543                     env->exit_request = 0;
 544                     env->exception_index = EXCP_INTERRUPT;
 545                     cpu_loop_exit(env);
 546                 }
 547 #if defined(DEBUG_DISAS) || defined(CONFIG_DEBUG_EXEC)
 548                 if (qemu_loglevel_mask(CPU_LOG_TB_CPU)) {
 549                     /* restore flags in standard format */
 550 #if defined(TARGET_I386)
 551                     env->eflags = env->eflags | cpu_cc_compute_all(env, CC_OP)
 552                         | (DF & DF_MASK);
 553                     log_cpu_state(env, CPU_DUMP_CCOP);
 554                     env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
 555 #elif defined(TARGET_M68K)
 556                     cpu_m68k_flush_flags(env, env->cc_op);
 557                     env->cc_op = CC_OP_FLAGS;
 558                     env->sr = (env->sr & 0xffe0)
 559                               | env->cc_dest | (env->cc_x << 4);
 560                     log_cpu_state(env, 0);
 561 #else
 562                     log_cpu_state(env, 0);
 563 #endif
 564                 }
 565 #endif /* DEBUG_DISAS || CONFIG_DEBUG_EXEC */
 566                 spin_lock(&tb_lock);
 567                 tb = tb_find_fast(env);
 568                 /* Note: we do it here to avoid a gcc bug on Mac OS X when
 569                    doing it in tb_find_slow */
 570                 if (tb_invalidated_flag) {
 571                     /* as some TB could have been invalidated because
 572                        of memory exceptions while generating the code, we
 573                        must recompute the hash index here */
 574                     next_tb = 0;
 575                     tb_invalidated_flag = 0;
 576                 }
 577 #ifdef CONFIG_DEBUG_EXEC
 578                 qemu_log_mask(CPU_LOG_EXEC, "Trace %p [" TARGET_FMT_lx "] %s\n",
 579                              tb->tc_ptr, tb->pc,
 580                              lookup_symbol(tb->pc));
 581 #endif
 582                 /* see if we can patch the calling TB. When the TB
 583                    spans two pages, we cannot safely do a direct
 584                    jump. */
 585                 if (next_tb != 0 && tb->page_addr[1] == -1) {
 586                     tb_add_jump((TranslationBlock *)(next_tb & ~3), next_tb & 3, tb);
 587                 }
 588                 spin_unlock(&tb_lock);
 589
 590                 /* cpu_interrupt might be called while translating the
 591                    TB, but before it is linked into a potentially
 592                    infinite loop and becomes env->current_tb. Avoid
 593                    starting execution if there is a pending interrupt. */
 594                 env->current_tb = tb;
 595                 barrier();
 596                 if (likely(!env->exit_request)) {
 597                     tc_ptr = tb->tc_ptr;
 598                     /* execute the generated code */
 599                     next_tb = tcg_qemu_tb_exec(env, tc_ptr);
 600                     if ((next_tb & 3) == 2) {
 601                         /* Instruction counter expired.  */
 602                         int insns_left;
 603                         tb = (TranslationBlock *)(next_tb & ~3);
 604                         /* Restore PC.  */
 605                         cpu_pc_from_tb(env, tb);
 606                         insns_left = env->icount_decr.u32;
 607                         if (env->icount_extra && insns_left >= 0) {
 608                             /* Refill decrementer and continue execution.  */
 609                             env->icount_extra += insns_left;
 610                             if (env->icount_extra > 0xffff) {
 611                                 insns_left = 0xffff;
 612                             } else {
 613                                 insns_left = env->icount_extra;
 614                             }
 615                             env->icount_extra -= insns_left;
 616                             env->icount_decr.u16.low = insns_left;
 617                         } else {
 618                             if (insns_left > 0) {
 619                                 /* Execute remaining instructions.  */
 620                                 cpu_exec_nocache(env, insns_left, tb);
 621                             }
 622                             env->exception_index = EXCP_INTERRUPT;
 623                             next_tb = 0;
 624                             cpu_loop_exit(env);
 625                         }
 626                     }
 627                 }
 628                 env->current_tb = NULL;
 629                 /* reset soft MMU for next block (it can currently
 630                    only be set by a memory fault) */
 631             } /* for(;;) */
 632         } else {
 633             /* Reload env after longjmp - the compiler may have smashed all
 634              * local variables as longjmp is marked 'noreturn'. */
 635             env = cpu_single_env;
 636         }
 637     } /* for(;;) */
 638
 639
 640 #if defined(TARGET_I386)
 641     /* restore flags in standard format */
 642     env->eflags = env->eflags | cpu_cc_compute_all(env, CC_OP)
 643         | (DF & DF_MASK);
 644 #elif defined(TARGET_ARM)
 645     /* XXX: Save/restore host fpu exception state?.  */
 646 #elif defined(TARGET_UNICORE32)
 647 #elif defined(TARGET_SPARC)
 648 #elif defined(TARGET_PPC)
 649 #elif defined(TARGET_LM32)
 650 #elif defined(TARGET_M68K)
 651     cpu_m68k_flush_flags(env, env->cc_op);
 652     env->cc_op = CC_OP_FLAGS;
 653     env->sr = (env->sr & 0xffe0)
 654               | env->cc_dest | (env->cc_x << 4);
 655 #elif defined(TARGET_MICROBLAZE)
 656 #elif defined(TARGET_MIPS)
 657 #elif defined(TARGET_OPENRISC)
 658 #elif defined(TARGET_SH4)
 659 #elif defined(TARGET_ALPHA)
 660 #elif defined(TARGET_CRIS)
 661 #elif defined(TARGET_S390X)
 662 #elif defined(TARGET_XTENSA)
 663     /* XXXXX */
 664 #else
 665 #error unsupported target CPU
 666 #endif
 667
 668     /* fail safe : never use cpu_single_env outside cpu_exec() */
 669     cpu_single_env = NULL;
 670     return ret;
 671 }