cpu-exec.c

   1 /*
   2  *  i386 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 "exec.h"
  21 #include "disas.h"
  22 #include "tcg.h"
  23 #include "qemu-barrier.h"
  24
  25 #if defined(__sparc__) && !defined(CONFIG_SOLARIS)
  26 // Work around ugly bugs in glibc that mangle global register contents
  27 #undef env
  28 #define env cpu_single_env
  29 #endif
  30
  31 int tb_invalidated_flag;
  32
  33 //#define CONFIG_DEBUG_EXEC
  34
  35 int qemu_cpu_has_work(CPUState *env)
  36 {
  37     return cpu_has_work(env);
  38 }
  39
  40 void cpu_loop_exit(void)
  41 {
  42     env->current_tb = NULL;
  43     longjmp(env->jmp_env, 1);
  44 }
  45
  46 /* exit the current TB from a signal handler. The host registers are
  47    restored in a state compatible with the CPU emulator
  48  */
  49 #if defined(CONFIG_SOFTMMU)
  50 void cpu_resume_from_signal(CPUState *env1, void *puc)
  51 {
  52     env = env1;
  53
  54     /* XXX: restore cpu registers saved in host registers */
  55
  56     env->exception_index = -1;
  57     longjmp(env->jmp_env, 1);
  58 }
  59 #endif
  60
  61 /* Execute the code without caching the generated code. An interpreter
  62    could be used if available. */
  63 static void cpu_exec_nocache(int max_cycles, TranslationBlock *orig_tb)
  64 {
  65     unsigned long next_tb;
  66     TranslationBlock *tb;
  67
  68     /* Should never happen.
  69        We only end up here when an existing TB is too long.  */
  70     if (max_cycles > CF_COUNT_MASK)
  71         max_cycles = CF_COUNT_MASK;
  72
  73     tb = tb_gen_code(env, orig_tb->pc, orig_tb->cs_base, orig_tb->flags,
  74                      max_cycles);
  75     env->current_tb = tb;
  76     /* execute the generated code */
  77     next_tb = tcg_qemu_tb_exec(tb->tc_ptr);
  78     env->current_tb = NULL;
  79
  80     if ((next_tb & 3) == 2) {
  81         /* Restore PC.  This may happen if async event occurs before
  82            the TB starts executing.  */
  83         cpu_pc_from_tb(env, tb);
  84     }
  85     tb_phys_invalidate(tb, -1);
  86     tb_free(tb);
  87 }
  88
  89 static TranslationBlock *tb_find_slow(target_ulong pc,
  90                                       target_ulong cs_base,
  91                                       uint64_t flags)
  92 {
  93     TranslationBlock *tb, **ptb1;
  94     unsigned int h;
  95     tb_page_addr_t phys_pc, phys_page1, phys_page2;
  96     target_ulong virt_page2;
  97
  98     tb_invalidated_flag = 0;
  99
 100     /* find translated block using physical mappings */
 101     phys_pc = get_page_addr_code(env, pc);
 102     phys_page1 = phys_pc & TARGET_PAGE_MASK;
 103     phys_page2 = -1;
 104     h = tb_phys_hash_func(phys_pc);
 105     ptb1 = &tb_phys_hash[h];
 106     for(;;) {
 107         tb = *ptb1;
 108         if (!tb)
 109             goto not_found;
 110         if (tb->pc == pc &&
 111             tb->page_addr[0] == phys_page1 &&
 112             tb->cs_base == cs_base &&
 113             tb->flags == flags) {
 114             /* check next page if needed */
 115             if (tb->page_addr[1] != -1) {
 116                 virt_page2 = (pc & TARGET_PAGE_MASK) +
 117                     TARGET_PAGE_SIZE;
 118                 phys_page2 = get_page_addr_code(env, virt_page2);
 119                 if (tb->page_addr[1] == phys_page2)
 120                     goto found;
 121             } else {
 122                 goto found;
 123             }
 124         }
 125         ptb1 = &tb->phys_hash_next;
 126     }
 127  not_found:
 128    /* if no translated code available, then translate it now */
 129     tb = tb_gen_code(env, pc, cs_base, flags, 0);
 130
 131  found:
 132     /* Move the last found TB to the head of the list */
 133     if (likely(*ptb1)) {
 134         *ptb1 = tb->phys_hash_next;
 135         tb->phys_hash_next = tb_phys_hash[h];
 136         tb_phys_hash[h] = tb;
 137     }
 138     /* we add the TB in the virtual pc hash table */
 139     env->tb_jmp_cache[tb_jmp_cache_hash_func(pc)] = tb;
 140     return tb;
 141 }
 142
 143 static inline TranslationBlock *tb_find_fast(void)
 144 {
 145     TranslationBlock *tb;
 146     target_ulong cs_base, pc;
 147     int flags;
 148
 149     /* we record a subset of the CPU state. It will
 150        always be the same before a given translated block
 151        is executed. */
 152     cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
 153     tb = env->tb_jmp_cache[tb_jmp_cache_hash_func(pc)];
 154     if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base ||
 155                  tb->flags != flags)) {
 156         tb = tb_find_slow(pc, cs_base, flags);
 157     }
 158     return tb;
 159 }
 160
 161 static CPUDebugExcpHandler *debug_excp_handler;
 162
 163 CPUDebugExcpHandler *cpu_set_debug_excp_handler(CPUDebugExcpHandler *handler)
 164 {
 165     CPUDebugExcpHandler *old_handler = debug_excp_handler;
 166
 167     debug_excp_handler = handler;
 168     return old_handler;
 169 }
 170
 171 static void cpu_handle_debug_exception(CPUState *env)
 172 {
 173     CPUWatchpoint *wp;
 174
 175     if (!env->watchpoint_hit) {
 176         QTAILQ_FOREACH(wp, &env->watchpoints, entry) {
 177             wp->flags &= ~BP_WATCHPOINT_HIT;
 178         }
 179     }
 180     if (debug_excp_handler) {
 181         debug_excp_handler(env);
 182     }
 183 }
 184
 185 /* main execution loop */
 186
 187 volatile sig_atomic_t exit_request;
 188
 189 int cpu_exec(CPUState *env1)
 190 {
 191     volatile host_reg_t saved_env_reg;
 192     int ret, interrupt_request;
 193     TranslationBlock *tb;
 194     uint8_t *tc_ptr;
 195     unsigned long next_tb;
 196
 197     if (env1->halted) {
 198         if (!cpu_has_work(env1)) {
 199             return EXCP_HALTED;
 200         }
 201
 202         env1->halted = 0;
 203     }
 204
 205     cpu_single_env = env1;
 206
 207     /* the access to env below is actually saving the global register's
 208        value, so that files not including target-xyz/exec.h are free to
 209        use it.  */
 210     QEMU_BUILD_BUG_ON (sizeof (saved_env_reg) != sizeof (env));
 211     saved_env_reg = (host_reg_t) env;
 212     barrier();
 213     env = env1;
 214
 215     if (unlikely(exit_request)) {
 216         env->exit_request = 1;
 217     }
 218
 219 #if defined(TARGET_I386)
 220     /* put eflags in CPU temporary format */
 221     CC_SRC = env->eflags & (CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
 222     DF = 1 - (2 * ((env->eflags >> 10) & 1));
 223     CC_OP = CC_OP_EFLAGS;
 224     env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
 225 #elif defined(TARGET_SPARC)
 226 #elif defined(TARGET_M68K)
 227     env->cc_op = CC_OP_FLAGS;
 228     env->cc_dest = env->sr & 0xf;
 229     env->cc_x = (env->sr >> 4) & 1;
 230 #elif defined(TARGET_ALPHA)
 231 #elif defined(TARGET_ARM)
 232 #elif defined(TARGET_UNICORE32)
 233 #elif defined(TARGET_PPC)
 234 #elif defined(TARGET_LM32)
 235 #elif defined(TARGET_MICROBLAZE)
 236 #elif defined(TARGET_MIPS)
 237 #elif defined(TARGET_SH4)
 238 #elif defined(TARGET_CRIS)
 239 #elif defined(TARGET_S390X)
 240     /* XXXXX */
 241 #else
 242 #error unsupported target CPU
 243 #endif
 244     env->exception_index = -1;
 245
 246     /* prepare setjmp context for exception handling */
 247     for(;;) {
 248         if (setjmp(env->jmp_env) == 0) {
 249 #if defined(__sparc__) && !defined(CONFIG_SOLARIS)
 250 #undef env
 251             env = cpu_single_env;
 252 #define env cpu_single_env
 253 #endif
 254             /* if an exception is pending, we execute it here */
 255             if (env->exception_index >= 0) {
 256                 if (env->exception_index >= EXCP_INTERRUPT) {
 257                     /* exit request from the cpu execution loop */
 258                     ret = env->exception_index;
 259                     if (ret == EXCP_DEBUG) {
 260                         cpu_handle_debug_exception(env);
 261                     }
 262                     break;
 263                 } else {
 264 #if defined(CONFIG_USER_ONLY)
 265                     /* if user mode only, we simulate a fake exception
 266                        which will be handled outside the cpu execution
 267                        loop */
 268 #if defined(TARGET_I386)
 269                     do_interrupt_user(env->exception_index,
 270                                       env->exception_is_int,
 271                                       env->error_code,
 272                                       env->exception_next_eip);
 273                     /* successfully delivered */
 274                     env->old_exception = -1;
 275 #endif
 276                     ret = env->exception_index;
 277                     break;
 278 #else
 279 #if defined(TARGET_I386)
 280                     /* simulate a real cpu exception. On i386, it can
 281                        trigger new exceptions, but we do not handle
 282                        double or triple faults yet. */
 283                     do_interrupt(env->exception_index,
 284                                  env->exception_is_int,
 285                                  env->error_code,
 286                                  env->exception_next_eip, 0);
 287                     /* successfully delivered */
 288                     env->old_exception = -1;
 289 #elif defined(TARGET_PPC)
 290                     do_interrupt(env);
 291 #elif defined(TARGET_LM32)
 292                     do_interrupt(env);
 293 #elif defined(TARGET_MICROBLAZE)
 294                     do_interrupt(env);
 295 #elif defined(TARGET_MIPS)
 296                     do_interrupt(env);
 297 #elif defined(TARGET_SPARC)
 298                     do_interrupt(env);
 299 #elif defined(TARGET_ARM)
 300                     do_interrupt(env);
 301 #elif defined(TARGET_UNICORE32)
 302                     do_interrupt(env);
 303 #elif defined(TARGET_SH4)
 304                     do_interrupt(env);
 305 #elif defined(TARGET_ALPHA)
 306                     do_interrupt(env);
 307 #elif defined(TARGET_CRIS)
 308                     do_interrupt(env);
 309 #elif defined(TARGET_M68K)
 310                     do_interrupt(0);
 311 #elif defined(TARGET_S390X)
 312                     do_interrupt(env);
 313 #endif
 314                     env->exception_index = -1;
 315 #endif
 316                 }
 317             }
 318
 319             next_tb = 0; /* force lookup of first TB */
 320             for(;;) {
 321                 interrupt_request = env->interrupt_request;
 322                 if (unlikely(interrupt_request)) {
 323                     if (unlikely(env->singlestep_enabled & SSTEP_NOIRQ)) {
 324                         /* Mask out external interrupts for this step. */
 325                         interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK;
 326                     }
 327                     if (interrupt_request & CPU_INTERRUPT_DEBUG) {
 328                         env->interrupt_request &= ~CPU_INTERRUPT_DEBUG;
 329                         env->exception_index = EXCP_DEBUG;
 330                         cpu_loop_exit();
 331                     }
 332 #if defined(TARGET_ARM) || defined(TARGET_SPARC) || defined(TARGET_MIPS) || \
 333     defined(TARGET_PPC) || defined(TARGET_ALPHA) || defined(TARGET_CRIS) || \
 334     defined(TARGET_MICROBLAZE) || defined(TARGET_LM32) || defined(TARGET_UNICORE32)
 335                     if (interrupt_request & CPU_INTERRUPT_HALT) {
 336                         env->interrupt_request &= ~CPU_INTERRUPT_HALT;
 337                         env->halted = 1;
 338                         env->exception_index = EXCP_HLT;
 339                         cpu_loop_exit();
 340                     }
 341 #endif
 342 #if defined(TARGET_I386)
 343                     if (interrupt_request & CPU_INTERRUPT_INIT) {
 344                             svm_check_intercept(SVM_EXIT_INIT);
 345                             do_cpu_init(env);
 346                             env->exception_index = EXCP_HALTED;
 347                             cpu_loop_exit();
 348                     } else if (interrupt_request & CPU_INTERRUPT_SIPI) {
 349                             do_cpu_sipi(env);
 350                     } else if (env->hflags2 & HF2_GIF_MASK) {
 351                         if ((interrupt_request & CPU_INTERRUPT_SMI) &&
 352                             !(env->hflags & HF_SMM_MASK)) {
 353                             svm_check_intercept(SVM_EXIT_SMI);
 354                             env->interrupt_request &= ~CPU_INTERRUPT_SMI;
 355                             do_smm_enter();
 356                             next_tb = 0;
 357                         } else if ((interrupt_request & CPU_INTERRUPT_NMI) &&
 358                                    !(env->hflags2 & HF2_NMI_MASK)) {
 359                             env->interrupt_request &= ~CPU_INTERRUPT_NMI;
 360                             env->hflags2 |= HF2_NMI_MASK;
 361                             do_interrupt(EXCP02_NMI, 0, 0, 0, 1);
 362                             next_tb = 0;
 363                         } else if (interrupt_request & CPU_INTERRUPT_MCE) {
 364                             env->interrupt_request &= ~CPU_INTERRUPT_MCE;
 365                             do_interrupt(EXCP12_MCHK, 0, 0, 0, 0);
 366                             next_tb = 0;
 367                         } else if ((interrupt_request & CPU_INTERRUPT_HARD) &&
 368                                    (((env->hflags2 & HF2_VINTR_MASK) &&
 369                                      (env->hflags2 & HF2_HIF_MASK)) ||
 370                                     (!(env->hflags2 & HF2_VINTR_MASK) &&
 371                                      (env->eflags & IF_MASK &&
 372                                       !(env->hflags & HF_INHIBIT_IRQ_MASK))))) {
 373                             int intno;
 374                             svm_check_intercept(SVM_EXIT_INTR);
 375                             env->interrupt_request &= ~(CPU_INTERRUPT_HARD | CPU_INTERRUPT_VIRQ);
 376                             intno = cpu_get_pic_interrupt(env);
 377                             qemu_log_mask(CPU_LOG_TB_IN_ASM, "Servicing hardware INT=0x%02x\n", intno);
 378 #if defined(__sparc__) && !defined(CONFIG_SOLARIS)
 379 #undef env
 380                     env = cpu_single_env;
 381 #define env cpu_single_env
 382 #endif
 383                             do_interrupt(intno, 0, 0, 0, 1);
 384                             /* ensure that no TB jump will be modified as
 385                                the program flow was changed */
 386                             next_tb = 0;
 387 #if !defined(CONFIG_USER_ONLY)
 388                         } else if ((interrupt_request & CPU_INTERRUPT_VIRQ) &&
 389                                    (env->eflags & IF_MASK) &&
 390                                    !(env->hflags & HF_INHIBIT_IRQ_MASK)) {
 391                             int intno;
 392                             /* FIXME: this should respect TPR */
 393                             svm_check_intercept(SVM_EXIT_VINTR);
 394                             intno = ldl_phys(env->vm_vmcb + offsetof(struct vmcb, control.int_vector));
 395                             qemu_log_mask(CPU_LOG_TB_IN_ASM, "Servicing virtual hardware INT=0x%02x\n", intno);
 396                             do_interrupt(intno, 0, 0, 0, 1);
 397                             env->interrupt_request &= ~CPU_INTERRUPT_VIRQ;
 398                             next_tb = 0;
 399 #endif
 400                         }
 401                     }
 402 #elif defined(TARGET_PPC)
 403 #if 0
 404                     if ((interrupt_request & CPU_INTERRUPT_RESET)) {
 405                         cpu_reset(env);
 406                     }
 407 #endif
 408                     if (interrupt_request & CPU_INTERRUPT_HARD) {
 409                         ppc_hw_interrupt(env);
 410                         if (env->pending_interrupts == 0)
 411                             env->interrupt_request &= ~CPU_INTERRUPT_HARD;
 412                         next_tb = 0;
 413                     }
 414 #elif defined(TARGET_LM32)
 415                     if ((interrupt_request & CPU_INTERRUPT_HARD)
 416                         && (env->ie & IE_IE)) {
 417                         env->exception_index = EXCP_IRQ;
 418                         do_interrupt(env);
 419                         next_tb = 0;
 420                     }
 421 #elif defined(TARGET_MICROBLAZE)
 422                     if ((interrupt_request & CPU_INTERRUPT_HARD)
 423                         && (env->sregs[SR_MSR] & MSR_IE)
 424                         && !(env->sregs[SR_MSR] & (MSR_EIP | MSR_BIP))
 425                         && !(env->iflags & (D_FLAG | IMM_FLAG))) {
 426                         env->exception_index = EXCP_IRQ;
 427                         do_interrupt(env);
 428                         next_tb = 0;
 429                     }
 430 #elif defined(TARGET_MIPS)
 431                     if ((interrupt_request & CPU_INTERRUPT_HARD) &&
 432                         cpu_mips_hw_interrupts_pending(env)) {
 433                         /* Raise it */
 434                         env->exception_index = EXCP_EXT_INTERRUPT;
 435                         env->error_code = 0;
 436                         do_interrupt(env);
 437                         next_tb = 0;
 438                     }
 439 #elif defined(TARGET_SPARC)
 440                     if (interrupt_request & CPU_INTERRUPT_HARD) {
 441                         if (cpu_interrupts_enabled(env) &&
 442                             env->interrupt_index > 0) {
 443                             int pil = env->interrupt_index & 0xf;
 444                             int type = env->interrupt_index & 0xf0;
 445
 446                             if (((type == TT_EXTINT) &&
 447                                   cpu_pil_allowed(env, pil)) ||
 448                                   type != TT_EXTINT) {
 449                                 env->exception_index = env->interrupt_index;
 450                                 do_interrupt(env);
 451                                 next_tb = 0;
 452                             }
 453                         }
 454                     }
 455 #elif defined(TARGET_ARM)
 456                     if (interrupt_request & CPU_INTERRUPT_FIQ
 457                         && !(env->uncached_cpsr & CPSR_F)) {
 458                         env->exception_index = EXCP_FIQ;
 459                         do_interrupt(env);
 460                         next_tb = 0;
 461                     }
 462                     /* ARMv7-M interrupt return works by loading a magic value
 463                        into the PC.  On real hardware the load causes the
 464                        return to occur.  The qemu implementation performs the
 465                        jump normally, then does the exception return when the
 466                        CPU tries to execute code at the magic address.
 467                        This will cause the magic PC value to be pushed to
 468                        the stack if an interrupt occurred at the wrong time.
 469                        We avoid this by disabling interrupts when
 470                        pc contains a magic address.  */
 471                     if (interrupt_request & CPU_INTERRUPT_HARD
 472                         && ((IS_M(env) && env->regs[15] < 0xfffffff0)
 473                             || !(env->uncached_cpsr & CPSR_I))) {
 474                         env->exception_index = EXCP_IRQ;
 475                         do_interrupt(env);
 476                         next_tb = 0;
 477                     }
 478 #elif defined(TARGET_UNICORE32)
 479                     if (interrupt_request & CPU_INTERRUPT_HARD
 480                         && !(env->uncached_asr & ASR_I)) {
 481                         do_interrupt(env);
 482                         next_tb = 0;
 483                     }
 484 #elif defined(TARGET_SH4)
 485                     if (interrupt_request & CPU_INTERRUPT_HARD) {
 486                         do_interrupt(env);
 487                         next_tb = 0;
 488                     }
 489 #elif defined(TARGET_ALPHA)
 490                     {
 491                         int idx = -1;
 492                         /* ??? This hard-codes the OSF/1 interrupt levels.  */
 493                         switch (env->pal_mode ? 7 : env->ps & PS_INT_MASK) {
 494                         case 0 ... 3:
 495                             if (interrupt_request & CPU_INTERRUPT_HARD) {
 496                                 idx = EXCP_DEV_INTERRUPT;
 497                             }
 498                             /* FALLTHRU */
 499                         case 4:
 500                             if (interrupt_request & CPU_INTERRUPT_TIMER) {
 501                                 idx = EXCP_CLK_INTERRUPT;
 502                             }
 503                             /* FALLTHRU */
 504                         case 5:
 505                             if (interrupt_request & CPU_INTERRUPT_SMP) {
 506                                 idx = EXCP_SMP_INTERRUPT;
 507                             }
 508                             /* FALLTHRU */
 509                         case 6:
 510                             if (interrupt_request & CPU_INTERRUPT_MCHK) {
 511                                 idx = EXCP_MCHK;
 512                             }
 513                         }
 514                         if (idx >= 0) {
 515                             env->exception_index = idx;
 516                             env->error_code = 0;
 517                             do_interrupt(env);
 518                             next_tb = 0;
 519                         }
 520                     }
 521 #elif defined(TARGET_CRIS)
 522                     if (interrupt_request & CPU_INTERRUPT_HARD
 523                         && (env->pregs[PR_CCS] & I_FLAG)
 524                         && !env->locked_irq) {
 525                         env->exception_index = EXCP_IRQ;
 526                         do_interrupt(env);
 527                         next_tb = 0;
 528                     }
 529                     if (interrupt_request & CPU_INTERRUPT_NMI
 530                         && (env->pregs[PR_CCS] & M_FLAG)) {
 531                         env->exception_index = EXCP_NMI;
 532                         do_interrupt(env);
 533                         next_tb = 0;
 534                     }
 535 #elif defined(TARGET_M68K)
 536                     if (interrupt_request & CPU_INTERRUPT_HARD
 537                         && ((env->sr & SR_I) >> SR_I_SHIFT)
 538                             < env->pending_level) {
 539                         /* Real hardware gets the interrupt vector via an
 540                            IACK cycle at this point.  Current emulated
 541                            hardware doesn't rely on this, so we
 542                            provide/save the vector when the interrupt is
 543                            first signalled.  */
 544                         env->exception_index = env->pending_vector;
 545                         do_interrupt(1);
 546                         next_tb = 0;
 547                     }
 548 #elif defined(TARGET_S390X) && !defined(CONFIG_USER_ONLY)
 549                     if ((interrupt_request & CPU_INTERRUPT_HARD) &&
 550                         (env->psw.mask & PSW_MASK_EXT)) {
 551                         do_interrupt(env);
 552                         next_tb = 0;
 553                     }
 554 #endif
 555                    /* Don't use the cached interrupt_request value,
 556                       do_interrupt may have updated the EXITTB flag. */
 557                     if (env->interrupt_request & CPU_INTERRUPT_EXITTB) {
 558                         env->interrupt_request &= ~CPU_INTERRUPT_EXITTB;
 559                         /* ensure that no TB jump will be modified as
 560                            the program flow was changed */
 561                         next_tb = 0;
 562                     }
 563                 }
 564                 if (unlikely(env->exit_request)) {
 565                     env->exit_request = 0;
 566                     env->exception_index = EXCP_INTERRUPT;
 567                     cpu_loop_exit();
 568                 }
 569 #if defined(DEBUG_DISAS) || defined(CONFIG_DEBUG_EXEC)
 570                 if (qemu_loglevel_mask(CPU_LOG_TB_CPU)) {
 571                     /* restore flags in standard format */
 572 #if defined(TARGET_I386)
 573                     env->eflags = env->eflags | helper_cc_compute_all(CC_OP) | (DF & DF_MASK);
 574                     log_cpu_state(env, X86_DUMP_CCOP);
 575                     env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
 576 #elif defined(TARGET_M68K)
 577                     cpu_m68k_flush_flags(env, env->cc_op);
 578                     env->cc_op = CC_OP_FLAGS;
 579                     env->sr = (env->sr & 0xffe0)
 580                               | env->cc_dest | (env->cc_x << 4);
 581                     log_cpu_state(env, 0);
 582 #else
 583                     log_cpu_state(env, 0);
 584 #endif
 585                 }
 586 #endif /* DEBUG_DISAS || CONFIG_DEBUG_EXEC */
 587                 spin_lock(&tb_lock);
 588                 tb = tb_find_fast();
 589                 /* Note: we do it here to avoid a gcc bug on Mac OS X when
 590                    doing it in tb_find_slow */
 591                 if (tb_invalidated_flag) {
 592                     /* as some TB could have been invalidated because
 593                        of memory exceptions while generating the code, we
 594                        must recompute the hash index here */
 595                     next_tb = 0;
 596                     tb_invalidated_flag = 0;
 597                 }
 598 #ifdef CONFIG_DEBUG_EXEC
 599                 qemu_log_mask(CPU_LOG_EXEC, "Trace 0x%08lx [" TARGET_FMT_lx "] %s\n",
 600                              (long)tb->tc_ptr, tb->pc,
 601                              lookup_symbol(tb->pc));
 602 #endif
 603                 /* see if we can patch the calling TB. When the TB
 604                    spans two pages, we cannot safely do a direct
 605                    jump. */
 606                 if (next_tb != 0 && tb->page_addr[1] == -1) {
 607                     tb_add_jump((TranslationBlock *)(next_tb & ~3), next_tb & 3, tb);
 608                 }
 609                 spin_unlock(&tb_lock);
 610
 611                 /* cpu_interrupt might be called while translating the
 612                    TB, but before it is linked into a potentially
 613                    infinite loop and becomes env->current_tb. Avoid
 614                    starting execution if there is a pending interrupt. */
 615                 env->current_tb = tb;
 616                 barrier();
 617                 if (likely(!env->exit_request)) {
 618                     tc_ptr = tb->tc_ptr;
 619                 /* execute the generated code */
 620 #if defined(__sparc__) && !defined(CONFIG_SOLARIS)
 621 #undef env
 622                     env = cpu_single_env;
 623 #define env cpu_single_env
 624 #endif
 625                     next_tb = tcg_qemu_tb_exec(tc_ptr);
 626                     if ((next_tb & 3) == 2) {
 627                         /* Instruction counter expired.  */
 628                         int insns_left;
 629                         tb = (TranslationBlock *)(long)(next_tb & ~3);
 630                         /* Restore PC.  */
 631                         cpu_pc_from_tb(env, tb);
 632                         insns_left = env->icount_decr.u32;
 633                         if (env->icount_extra && insns_left >= 0) {
 634                             /* Refill decrementer and continue execution.  */
 635                             env->icount_extra += insns_left;
 636                             if (env->icount_extra > 0xffff) {
 637                                 insns_left = 0xffff;
 638                             } else {
 639                                 insns_left = env->icount_extra;
 640                             }
 641                             env->icount_extra -= insns_left;
 642                             env->icount_decr.u16.low = insns_left;
 643                         } else {
 644                             if (insns_left > 0) {
 645                                 /* Execute remaining instructions.  */
 646                                 cpu_exec_nocache(insns_left, tb);
 647                             }
 648                             env->exception_index = EXCP_INTERRUPT;
 649                             next_tb = 0;
 650                             cpu_loop_exit();
 651                         }
 652                     }
 653                 }
 654                 env->current_tb = NULL;
 655                 /* reset soft MMU for next block (it can currently
 656                    only be set by a memory fault) */
 657             } /* for(;;) */
 658         }
 659     } /* for(;;) */
 660
 661
 662 #if defined(TARGET_I386)
 663     /* restore flags in standard format */
 664     env->eflags = env->eflags | helper_cc_compute_all(CC_OP) | (DF & DF_MASK);
 665 #elif defined(TARGET_ARM)
 666     /* XXX: Save/restore host fpu exception state?.  */
 667 #elif defined(TARGET_UNICORE32)
 668 #elif defined(TARGET_SPARC)
 669 #elif defined(TARGET_PPC)
 670 #elif defined(TARGET_LM32)
 671 #elif defined(TARGET_M68K)
 672     cpu_m68k_flush_flags(env, env->cc_op);
 673     env->cc_op = CC_OP_FLAGS;
 674     env->sr = (env->sr & 0xffe0)
 675               | env->cc_dest | (env->cc_x << 4);
 676 #elif defined(TARGET_MICROBLAZE)
 677 #elif defined(TARGET_MIPS)
 678 #elif defined(TARGET_SH4)
 679 #elif defined(TARGET_ALPHA)
 680 #elif defined(TARGET_CRIS)
 681 #elif defined(TARGET_S390X)
 682     /* XXXXX */
 683 #else
 684 #error unsupported target CPU
 685 #endif
 686
 687     /* restore global registers */
 688     barrier();
 689     env = (void *) saved_env_reg;
 690
 691     /* fail safe : never use cpu_single_env outside cpu_exec() */
 692     cpu_single_env = NULL;
 693     return ret;
 694 }