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 //#define CONFIG_DEBUG_EXEC
  27
  28 bool qemu_cpu_has_work(CPUState *cpu)
  29 {
  30     return cpu_has_work(cpu);
  31 }
  32
  33 void cpu_loop_exit(CPUArchState *env)
  34 {
  35     CPUState *cpu = ENV_GET_CPU(env);
  36
  37     cpu->current_tb = NULL;
  38     siglongjmp(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     siglongjmp(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     CPUState *cpu = ENV_GET_CPU(env);
  60     tcg_target_ulong next_tb;
  61     TranslationBlock *tb;
  62
  63     /* Should never happen.
  64        We only end up here when an existing TB is too long.  */
  65     if (max_cycles > CF_COUNT_MASK)
  66         max_cycles = CF_COUNT_MASK;
  67
  68     tb = tb_gen_code(env, orig_tb->pc, orig_tb->cs_base, orig_tb->flags,
  69                      max_cycles);
  70     cpu->current_tb = tb;
  71     /* execute the generated code */
  72     next_tb = tcg_qemu_tb_exec(env, tb->tc_ptr);
  73     cpu->current_tb = NULL;
  74
  75     if ((next_tb & 3) == 2) {
  76         /* Restore PC.  This may happen if async event occurs before
  77            the TB starts executing.  */
  78         cpu_pc_from_tb(env, tb);
  79     }
  80     tb_phys_invalidate(tb, -1);
  81     tb_free(tb);
  82 }
  83
  84 static TranslationBlock *tb_find_slow(CPUArchState *env,
  85                                       target_ulong pc,
  86                                       target_ulong cs_base,
  87                                       uint64_t flags)
  88 {
  89     TranslationBlock *tb, **ptb1;
  90     unsigned int h;
  91     tb_page_addr_t phys_pc, phys_page1;
  92     target_ulong virt_page2;
  93
  94     tcg_ctx.tb_ctx.tb_invalidated_flag = 0;
  95
  96     /* find translated block using physical mappings */
  97     phys_pc = get_page_addr_code(env, pc);
  98     phys_page1 = phys_pc & TARGET_PAGE_MASK;
  99     h = tb_phys_hash_func(phys_pc);
 100     ptb1 = &tcg_ctx.tb_ctx.tb_phys_hash[h];
 101     for(;;) {
 102         tb = *ptb1;
 103         if (!tb)
 104             goto not_found;
 105         if (tb->pc == pc &&
 106             tb->page_addr[0] == phys_page1 &&
 107             tb->cs_base == cs_base &&
 108             tb->flags == flags) {
 109             /* check next page if needed */
 110             if (tb->page_addr[1] != -1) {
 111                 tb_page_addr_t phys_page2;
 112
 113                 virt_page2 = (pc & TARGET_PAGE_MASK) +
 114                     TARGET_PAGE_SIZE;
 115                 phys_page2 = get_page_addr_code(env, virt_page2);
 116                 if (tb->page_addr[1] == phys_page2)
 117                     goto found;
 118             } else {
 119                 goto found;
 120             }
 121         }
 122         ptb1 = &tb->phys_hash_next;
 123     }
 124  not_found:
 125    /* if no translated code available, then translate it now */
 126     tb = tb_gen_code(env, pc, cs_base, flags, 0);
 127
 128  found:
 129     /* Move the last found TB to the head of the list */
 130     if (likely(*ptb1)) {
 131         *ptb1 = tb->phys_hash_next;
 132         tb->phys_hash_next = tcg_ctx.tb_ctx.tb_phys_hash[h];
 133         tcg_ctx.tb_ctx.tb_phys_hash[h] = tb;
 134     }
 135     /* we add the TB in the virtual pc hash table */
 136     env->tb_jmp_cache[tb_jmp_cache_hash_func(pc)] = tb;
 137     return tb;
 138 }
 139
 140 static inline TranslationBlock *tb_find_fast(CPUArchState *env)
 141 {
 142     TranslationBlock *tb;
 143     target_ulong cs_base, pc;
 144     int flags;
 145
 146     /* we record a subset of the CPU state. It will
 147        always be the same before a given translated block
 148        is executed. */
 149     cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
 150     tb = env->tb_jmp_cache[tb_jmp_cache_hash_func(pc)];
 151     if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base ||
 152                  tb->flags != flags)) {
 153         tb = tb_find_slow(env, pc, cs_base, flags);
 154     }
 155     return tb;
 156 }
 157
 158 static CPUDebugExcpHandler *debug_excp_handler;
 159
 160 void cpu_set_debug_excp_handler(CPUDebugExcpHandler *handler)
 161 {
 162     debug_excp_handler = handler;
 163 }
 164
 165 static void cpu_handle_debug_exception(CPUArchState *env)
 166 {
 167     CPUWatchpoint *wp;
 168
 169     if (!env->watchpoint_hit) {
 170         QTAILQ_FOREACH(wp, &env->watchpoints, entry) {
 171             wp->flags &= ~BP_WATCHPOINT_HIT;
 172         }
 173     }
 174     if (debug_excp_handler) {
 175         debug_excp_handler(env);
 176     }
 177 }
 178
 179 /* main execution loop */
 180
 181 volatile sig_atomic_t exit_request;
 182
 183 int cpu_exec(CPUArchState *env)
 184 {
 185     CPUState *cpu = ENV_GET_CPU(env);
 186     int ret, interrupt_request;
 187     TranslationBlock *tb;
 188     uint8_t *tc_ptr;
 189     tcg_target_ulong next_tb;
 190
 191     if (env->halted) {
 192         if (!cpu_has_work(cpu)) {
 193             return EXCP_HALTED;
 194         }
 195
 196         env->halted = 0;
 197     }
 198
 199     cpu_single_env = env;
 200
 201     if (unlikely(exit_request)) {
 202         cpu->exit_request = 1;
 203     }
 204
 205 #if defined(TARGET_I386)
 206     /* put eflags in CPU temporary format */
 207     CC_SRC = env->eflags & (CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
 208     DF = 1 - (2 * ((env->eflags >> 10) & 1));
 209     CC_OP = CC_OP_EFLAGS;
 210     env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
 211 #elif defined(TARGET_SPARC)
 212 #elif defined(TARGET_M68K)
 213     env->cc_op = CC_OP_FLAGS;
 214     env->cc_dest = env->sr & 0xf;
 215     env->cc_x = (env->sr >> 4) & 1;
 216 #elif defined(TARGET_ALPHA)
 217 #elif defined(TARGET_ARM)
 218 #elif defined(TARGET_UNICORE32)
 219 #elif defined(TARGET_PPC)
 220     env->reserve_addr = -1;
 221 #elif defined(TARGET_LM32)
 222 #elif defined(TARGET_MICROBLAZE)
 223 #elif defined(TARGET_MIPS)
 224 #elif defined(TARGET_OPENRISC)
 225 #elif defined(TARGET_SH4)
 226 #elif defined(TARGET_CRIS)
 227 #elif defined(TARGET_S390X)
 228 #elif defined(TARGET_XTENSA)
 229     /* XXXXX */
 230 #else
 231 #error unsupported target CPU
 232 #endif
 233     env->exception_index = -1;
 234
 235     /* prepare setjmp context for exception handling */
 236     for(;;) {
 237         if (sigsetjmp(env->jmp_env, 0) == 0) {
 238             /* if an exception is pending, we execute it here */
 239             if (env->exception_index >= 0) {
 240                 if (env->exception_index >= EXCP_INTERRUPT) {
 241                     /* exit request from the cpu execution loop */
 242                     ret = env->exception_index;
 243                     if (ret == EXCP_DEBUG) {
 244                         cpu_handle_debug_exception(env);
 245                     }
 246                     break;
 247                 } else {
 248 #if defined(CONFIG_USER_ONLY)
 249                     /* if user mode only, we simulate a fake exception
 250                        which will be handled outside the cpu execution
 251                        loop */
 252 #if defined(TARGET_I386)
 253                     do_interrupt(env);
 254 #endif
 255                     ret = env->exception_index;
 256                     break;
 257 #else
 258                     do_interrupt(env);
 259                     env->exception_index = -1;
 260 #endif
 261                 }
 262             }
 263
 264             next_tb = 0; /* force lookup of first TB */
 265             for(;;) {
 266                 interrupt_request = env->interrupt_request;
 267                 if (unlikely(interrupt_request)) {
 268                     if (unlikely(env->singlestep_enabled & SSTEP_NOIRQ)) {
 269                         /* Mask out external interrupts for this step. */
 270                         interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK;
 271                     }
 272                     if (interrupt_request & CPU_INTERRUPT_DEBUG) {
 273                         env->interrupt_request &= ~CPU_INTERRUPT_DEBUG;
 274                         env->exception_index = EXCP_DEBUG;
 275                         cpu_loop_exit(env);
 276                     }
 277 #if defined(TARGET_ARM) || defined(TARGET_SPARC) || defined(TARGET_MIPS) || \
 278     defined(TARGET_PPC) || defined(TARGET_ALPHA) || defined(TARGET_CRIS) || \
 279     defined(TARGET_MICROBLAZE) || defined(TARGET_LM32) || defined(TARGET_UNICORE32)
 280                     if (interrupt_request & CPU_INTERRUPT_HALT) {
 281                         env->interrupt_request &= ~CPU_INTERRUPT_HALT;
 282                         env->halted = 1;
 283                         env->exception_index = EXCP_HLT;
 284                         cpu_loop_exit(env);
 285                     }
 286 #endif
 287 #if defined(TARGET_I386)
 288 #if !defined(CONFIG_USER_ONLY)
 289                     if (interrupt_request & CPU_INTERRUPT_POLL) {
 290                         env->interrupt_request &= ~CPU_INTERRUPT_POLL;
 291                         apic_poll_irq(env->apic_state);
 292                     }
 293 #endif
 294                     if (interrupt_request & CPU_INTERRUPT_INIT) {
 295                             cpu_svm_check_intercept_param(env, SVM_EXIT_INIT,
 296                                                           0);
 297                             do_cpu_init(x86_env_get_cpu(env));
 298                             env->exception_index = EXCP_HALTED;
 299                             cpu_loop_exit(env);
 300                     } else if (interrupt_request & CPU_INTERRUPT_SIPI) {
 301                             do_cpu_sipi(x86_env_get_cpu(env));
 302                     } else if (env->hflags2 & HF2_GIF_MASK) {
 303                         if ((interrupt_request & CPU_INTERRUPT_SMI) &&
 304                             !(env->hflags & HF_SMM_MASK)) {
 305                             cpu_svm_check_intercept_param(env, SVM_EXIT_SMI,
 306                                                           0);
 307                             env->interrupt_request &= ~CPU_INTERRUPT_SMI;
 308                             do_smm_enter(env);
 309                             next_tb = 0;
 310                         } else if ((interrupt_request & CPU_INTERRUPT_NMI) &&
 311                                    !(env->hflags2 & HF2_NMI_MASK)) {
 312                             env->interrupt_request &= ~CPU_INTERRUPT_NMI;
 313                             env->hflags2 |= HF2_NMI_MASK;
 314                             do_interrupt_x86_hardirq(env, EXCP02_NMI, 1);
 315                             next_tb = 0;
 316                         } else if (interrupt_request & CPU_INTERRUPT_MCE) {
 317                             env->interrupt_request &= ~CPU_INTERRUPT_MCE;
 318                             do_interrupt_x86_hardirq(env, EXCP12_MCHK, 0);
 319                             next_tb = 0;
 320                         } else if ((interrupt_request & CPU_INTERRUPT_HARD) &&
 321                                    (((env->hflags2 & HF2_VINTR_MASK) &&
 322                                      (env->hflags2 & HF2_HIF_MASK)) ||
 323                                     (!(env->hflags2 & HF2_VINTR_MASK) &&
 324                                      (env->eflags & IF_MASK &&
 325                                       !(env->hflags & HF_INHIBIT_IRQ_MASK))))) {
 326                             int intno;
 327                             cpu_svm_check_intercept_param(env, SVM_EXIT_INTR,
 328                                                           0);
 329                             env->interrupt_request &= ~(CPU_INTERRUPT_HARD | CPU_INTERRUPT_VIRQ);
 330                             intno = cpu_get_pic_interrupt(env);
 331                             qemu_log_mask(CPU_LOG_TB_IN_ASM, "Servicing hardware INT=0x%02x\n", intno);
 332                             do_interrupt_x86_hardirq(env, intno, 1);
 333                             /* ensure that no TB jump will be modified as
 334                                the program flow was changed */
 335                             next_tb = 0;
 336 #if !defined(CONFIG_USER_ONLY)
 337                         } else if ((interrupt_request & CPU_INTERRUPT_VIRQ) &&
 338                                    (env->eflags & IF_MASK) &&
 339                                    !(env->hflags & HF_INHIBIT_IRQ_MASK)) {
 340                             int intno;
 341                             /* FIXME: this should respect TPR */
 342                             cpu_svm_check_intercept_param(env, SVM_EXIT_VINTR,
 343                                                           0);
 344                             intno = ldl_phys(env->vm_vmcb + offsetof(struct vmcb, control.int_vector));
 345                             qemu_log_mask(CPU_LOG_TB_IN_ASM, "Servicing virtual hardware INT=0x%02x\n", intno);
 346                             do_interrupt_x86_hardirq(env, intno, 1);
 347                             env->interrupt_request &= ~CPU_INTERRUPT_VIRQ;
 348                             next_tb = 0;
 349 #endif
 350                         }
 351                     }
 352 #elif defined(TARGET_PPC)
 353                     if ((interrupt_request & CPU_INTERRUPT_RESET)) {
 354                         cpu_reset(cpu);
 355                     }
 356                     if (interrupt_request & CPU_INTERRUPT_HARD) {
 357                         ppc_hw_interrupt(env);
 358                         if (env->pending_interrupts == 0)
 359                             env->interrupt_request &= ~CPU_INTERRUPT_HARD;
 360                         next_tb = 0;
 361                     }
 362 #elif defined(TARGET_LM32)
 363                     if ((interrupt_request & CPU_INTERRUPT_HARD)
 364                         && (env->ie & IE_IE)) {
 365                         env->exception_index = EXCP_IRQ;
 366                         do_interrupt(env);
 367                         next_tb = 0;
 368                     }
 369 #elif defined(TARGET_MICROBLAZE)
 370                     if ((interrupt_request & CPU_INTERRUPT_HARD)
 371                         && (env->sregs[SR_MSR] & MSR_IE)
 372                         && !(env->sregs[SR_MSR] & (MSR_EIP | MSR_BIP))
 373                         && !(env->iflags & (D_FLAG | IMM_FLAG))) {
 374                         env->exception_index = EXCP_IRQ;
 375                         do_interrupt(env);
 376                         next_tb = 0;
 377                     }
 378 #elif defined(TARGET_MIPS)
 379                     if ((interrupt_request & CPU_INTERRUPT_HARD) &&
 380                         cpu_mips_hw_interrupts_pending(env)) {
 381                         /* Raise it */
 382                         env->exception_index = EXCP_EXT_INTERRUPT;
 383                         env->error_code = 0;
 384                         do_interrupt(env);
 385                         next_tb = 0;
 386                     }
 387 #elif defined(TARGET_OPENRISC)
 388                     {
 389                         int idx = -1;
 390                         if ((interrupt_request & CPU_INTERRUPT_HARD)
 391                             && (env->sr & SR_IEE)) {
 392                             idx = EXCP_INT;
 393                         }
 394                         if ((interrupt_request & CPU_INTERRUPT_TIMER)
 395                             && (env->sr & SR_TEE)) {
 396                             idx = EXCP_TICK;
 397                         }
 398                         if (idx >= 0) {
 399                             env->exception_index = idx;
 400                             do_interrupt(env);
 401                             next_tb = 0;
 402                         }
 403                     }
 404 #elif defined(TARGET_SPARC)
 405                     if (interrupt_request & CPU_INTERRUPT_HARD) {
 406                         if (cpu_interrupts_enabled(env) &&
 407                             env->interrupt_index > 0) {
 408                             int pil = env->interrupt_index & 0xf;
 409                             int type = env->interrupt_index & 0xf0;
 410
 411                             if (((type == TT_EXTINT) &&
 412                                   cpu_pil_allowed(env, pil)) ||
 413                                   type != TT_EXTINT) {
 414                                 env->exception_index = env->interrupt_index;
 415                                 do_interrupt(env);
 416                                 next_tb = 0;
 417                             }
 418                         }
 419                     }
 420 #elif defined(TARGET_ARM)
 421                     if (interrupt_request & CPU_INTERRUPT_FIQ
 422                         && !(env->uncached_cpsr & CPSR_F)) {
 423                         env->exception_index = EXCP_FIQ;
 424                         do_interrupt(env);
 425                         next_tb = 0;
 426                     }
 427                     /* ARMv7-M interrupt return works by loading a magic value
 428                        into the PC.  On real hardware the load causes the
 429                        return to occur.  The qemu implementation performs the
 430                        jump normally, then does the exception return when the
 431                        CPU tries to execute code at the magic address.
 432                        This will cause the magic PC value to be pushed to
 433                        the stack if an interrupt occurred at the wrong time.
 434                        We avoid this by disabling interrupts when
 435                        pc contains a magic address.  */
 436                     if (interrupt_request & CPU_INTERRUPT_HARD
 437                         && ((IS_M(env) && env->regs[15] < 0xfffffff0)
 438                             || !(env->uncached_cpsr & CPSR_I))) {
 439                         env->exception_index = EXCP_IRQ;
 440                         do_interrupt(env);
 441                         next_tb = 0;
 442                     }
 443 #elif defined(TARGET_UNICORE32)
 444                     if (interrupt_request & CPU_INTERRUPT_HARD
 445                         && !(env->uncached_asr & ASR_I)) {
 446                         env->exception_index = UC32_EXCP_INTR;
 447                         do_interrupt(env);
 448                         next_tb = 0;
 449                     }
 450 #elif defined(TARGET_SH4)
 451                     if (interrupt_request & CPU_INTERRUPT_HARD) {
 452                         do_interrupt(env);
 453                         next_tb = 0;
 454                     }
 455 #elif defined(TARGET_ALPHA)
 456                     {
 457                         int idx = -1;
 458                         /* ??? This hard-codes the OSF/1 interrupt levels.  */
 459                         switch (env->pal_mode ? 7 : env->ps & PS_INT_MASK) {
 460                         case 0 ... 3:
 461                             if (interrupt_request & CPU_INTERRUPT_HARD) {
 462                                 idx = EXCP_DEV_INTERRUPT;
 463                             }
 464                             /* FALLTHRU */
 465                         case 4:
 466                             if (interrupt_request & CPU_INTERRUPT_TIMER) {
 467                                 idx = EXCP_CLK_INTERRUPT;
 468                             }
 469                             /* FALLTHRU */
 470                         case 5:
 471                             if (interrupt_request & CPU_INTERRUPT_SMP) {
 472                                 idx = EXCP_SMP_INTERRUPT;
 473                             }
 474                             /* FALLTHRU */
 475                         case 6:
 476                             if (interrupt_request & CPU_INTERRUPT_MCHK) {
 477                                 idx = EXCP_MCHK;
 478                             }
 479                         }
 480                         if (idx >= 0) {
 481                             env->exception_index = idx;
 482                             env->error_code = 0;
 483                             do_interrupt(env);
 484                             next_tb = 0;
 485                         }
 486                     }
 487 #elif defined(TARGET_CRIS)
 488                     if (interrupt_request & CPU_INTERRUPT_HARD
 489                         && (env->pregs[PR_CCS] & I_FLAG)
 490                         && !env->locked_irq) {
 491                         env->exception_index = EXCP_IRQ;
 492                         do_interrupt(env);
 493                         next_tb = 0;
 494                     }
 495                     if (interrupt_request & CPU_INTERRUPT_NMI) {
 496                         unsigned int m_flag_archval;
 497                         if (env->pregs[PR_VR] < 32) {
 498                             m_flag_archval = M_FLAG_V10;
 499                         } else {
 500                             m_flag_archval = M_FLAG_V32;
 501                         }
 502                         if ((env->pregs[PR_CCS] & m_flag_archval)) {
 503                             env->exception_index = EXCP_NMI;
 504                             do_interrupt(env);
 505                             next_tb = 0;
 506                         }
 507                     }
 508 #elif defined(TARGET_M68K)
 509                     if (interrupt_request & CPU_INTERRUPT_HARD
 510                         && ((env->sr & SR_I) >> SR_I_SHIFT)
 511                             < env->pending_level) {
 512                         /* Real hardware gets the interrupt vector via an
 513                            IACK cycle at this point.  Current emulated
 514                            hardware doesn't rely on this, so we
 515                            provide/save the vector when the interrupt is
 516                            first signalled.  */
 517                         env->exception_index = env->pending_vector;
 518                         do_interrupt_m68k_hardirq(env);
 519                         next_tb = 0;
 520                     }
 521 #elif defined(TARGET_S390X) && !defined(CONFIG_USER_ONLY)
 522                     if ((interrupt_request & CPU_INTERRUPT_HARD) &&
 523                         (env->psw.mask & PSW_MASK_EXT)) {
 524                         do_interrupt(env);
 525                         next_tb = 0;
 526                     }
 527 #elif defined(TARGET_XTENSA)
 528                     if (interrupt_request & CPU_INTERRUPT_HARD) {
 529                         env->exception_index = EXC_IRQ;
 530                         do_interrupt(env);
 531                         next_tb = 0;
 532                     }
 533 #endif
 534                    /* Don't use the cached interrupt_request value,
 535                       do_interrupt may have updated the EXITTB flag. */
 536                     if (env->interrupt_request & CPU_INTERRUPT_EXITTB) {
 537                         env->interrupt_request &= ~CPU_INTERRUPT_EXITTB;
 538                         /* ensure that no TB jump will be modified as
 539                            the program flow was changed */
 540                         next_tb = 0;
 541                     }
 542                 }
 543                 if (unlikely(cpu->exit_request)) {
 544                     cpu->exit_request = 0;
 545                     env->exception_index = EXCP_INTERRUPT;
 546                     cpu_loop_exit(env);
 547                 }
 548 #if defined(DEBUG_DISAS) || defined(CONFIG_DEBUG_EXEC)
 549                 if (qemu_loglevel_mask(CPU_LOG_TB_CPU)) {
 550                     /* restore flags in standard format */
 551 #if defined(TARGET_I386)
 552                     env->eflags = env->eflags | cpu_cc_compute_all(env, CC_OP)
 553                         | (DF & DF_MASK);
 554                     log_cpu_state(env, CPU_DUMP_CCOP);
 555                     env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
 556 #elif defined(TARGET_M68K)
 557                     cpu_m68k_flush_flags(env, env->cc_op);
 558                     env->cc_op = CC_OP_FLAGS;
 559                     env->sr = (env->sr & 0xffe0)
 560                               | env->cc_dest | (env->cc_x << 4);
 561                     log_cpu_state(env, 0);
 562 #else
 563                     log_cpu_state(env, 0);
 564 #endif
 565                 }
 566 #endif /* DEBUG_DISAS || CONFIG_DEBUG_EXEC */
 567                 spin_lock(&tcg_ctx.tb_ctx.tb_lock);
 568                 tb = tb_find_fast(env);
 569                 /* Note: we do it here to avoid a gcc bug on Mac OS X when
 570                    doing it in tb_find_slow */
 571                 if (tcg_ctx.tb_ctx.tb_invalidated_flag) {
 572                     /* as some TB could have been invalidated because
 573                        of memory exceptions while generating the code, we
 574                        must recompute the hash index here */
 575                     next_tb = 0;
 576                     tcg_ctx.tb_ctx.tb_invalidated_flag = 0;
 577                 }
 578 #ifdef CONFIG_DEBUG_EXEC
 579                 qemu_log_mask(CPU_LOG_EXEC, "Trace %p [" TARGET_FMT_lx "] %s\n",
 580                              tb->tc_ptr, tb->pc,
 581                              lookup_symbol(tb->pc));
 582 #endif
 583                 /* see if we can patch the calling TB. When the TB
 584                    spans two pages, we cannot safely do a direct
 585                    jump. */
 586                 if (next_tb != 0 && tb->page_addr[1] == -1) {
 587                     tb_add_jump((TranslationBlock *)(next_tb & ~3), next_tb & 3, tb);
 588                 }
 589                 spin_unlock(&tcg_ctx.tb_ctx.tb_lock);
 590
 591                 /* cpu_interrupt might be called while translating the
 592                    TB, but before it is linked into a potentially
 593                    infinite loop and becomes env->current_tb. Avoid
 594                    starting execution if there is a pending interrupt. */
 595                 cpu->current_tb = tb;
 596                 barrier();
 597                 if (likely(!cpu->exit_request)) {
 598                     tc_ptr = tb->tc_ptr;
 599                     /* execute the generated code */
 600                     next_tb = tcg_qemu_tb_exec(env, tc_ptr);
 601                     if ((next_tb & 3) == 2) {
 602                         /* Instruction counter expired.  */
 603                         int insns_left;
 604                         tb = (TranslationBlock *)(next_tb & ~3);
 605                         /* Restore PC.  */
 606                         cpu_pc_from_tb(env, tb);
 607                         insns_left = env->icount_decr.u32;
 608                         if (env->icount_extra && insns_left >= 0) {
 609                             /* Refill decrementer and continue execution.  */
 610                             env->icount_extra += insns_left;
 611                             if (env->icount_extra > 0xffff) {
 612                                 insns_left = 0xffff;
 613                             } else {
 614                                 insns_left = env->icount_extra;
 615                             }
 616                             env->icount_extra -= insns_left;
 617                             env->icount_decr.u16.low = insns_left;
 618                         } else {
 619                             if (insns_left > 0) {
 620                                 /* Execute remaining instructions.  */
 621                                 cpu_exec_nocache(env, insns_left, tb);
 622                             }
 623                             env->exception_index = EXCP_INTERRUPT;
 624                             next_tb = 0;
 625                             cpu_loop_exit(env);
 626                         }
 627                     }
 628                 }
 629                 cpu->current_tb = NULL;
 630                 /* reset soft MMU for next block (it can currently
 631                    only be set by a memory fault) */
 632             } /* for(;;) */
 633         } else {
 634             /* Reload env after longjmp - the compiler may have smashed all
 635              * local variables as longjmp is marked 'noreturn'. */
 636             env = cpu_single_env;
 637         }
 638     } /* for(;;) */
 639
 640
 641 #if defined(TARGET_I386)
 642     /* restore flags in standard format */
 643     env->eflags = env->eflags | cpu_cc_compute_all(env, CC_OP)
 644         | (DF & DF_MASK);
 645 #elif defined(TARGET_ARM)
 646     /* XXX: Save/restore host fpu exception state?.  */
 647 #elif defined(TARGET_UNICORE32)
 648 #elif defined(TARGET_SPARC)
 649 #elif defined(TARGET_PPC)
 650 #elif defined(TARGET_LM32)
 651 #elif defined(TARGET_M68K)
 652     cpu_m68k_flush_flags(env, env->cc_op);
 653     env->cc_op = CC_OP_FLAGS;
 654     env->sr = (env->sr & 0xffe0)
 655               | env->cc_dest | (env->cc_x << 4);
 656 #elif defined(TARGET_MICROBLAZE)
 657 #elif defined(TARGET_MIPS)
 658 #elif defined(TARGET_OPENRISC)
 659 #elif defined(TARGET_SH4)
 660 #elif defined(TARGET_ALPHA)
 661 #elif defined(TARGET_CRIS)
 662 #elif defined(TARGET_S390X)
 663 #elif defined(TARGET_XTENSA)
 664     /* XXXXX */
 665 #else
 666 #error unsupported target CPU
 667 #endif
 668
 669     /* fail safe : never use cpu_single_env outside cpu_exec() */
 670     cpu_single_env = NULL;
 671     return ret;
 672 }