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 2.1 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
20#include "qemu/osdep.h"
21#include "qemu-common.h"
22#include "cpu.h"
23#include "trace.h"
24#include "disas/disas.h"
25#include "exec/exec-all.h"
26#include "tcg.h"
27#include "qemu/atomic.h"
28#include "sysemu/qtest.h"
29#include "qemu/timer.h"
30#include "qemu/rcu.h"
31#include "exec/tb-hash.h"
32#include "exec/tb-lookup.h"
33#include "exec/log.h"
34#include "qemu/main-loop.h"
35#if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
36#include "hw/i386/apic.h"
37#endif
38#include "sysemu/cpus.h"
39#include "sysemu/replay.h"
40
41/* -icount align implementation. */
42
43typedef struct SyncClocks {
44 int64_t diff_clk;
45 int64_t last_cpu_icount;
46 int64_t realtime_clock;
47} SyncClocks;
48
49#if !defined(CONFIG_USER_ONLY)
50/* Allow the guest to have a max 3ms advance.
51 * The difference between the 2 clocks could therefore
52 * oscillate around 0.
53 */
54#define VM_CLOCK_ADVANCE 3000000
55#define THRESHOLD_REDUCE 1.5
56#define MAX_DELAY_PRINT_RATE 2000000000LL
57#define MAX_NB_PRINTS 100
58
59static void align_clocks(SyncClocks *sc, CPUState *cpu)
60{
61 int64_t cpu_icount;
62
63 if (!icount_align_option) {
64 return;
65 }
66
67 cpu_icount = cpu->icount_extra + cpu_neg(cpu)->icount_decr.u16.low;
68 sc->diff_clk += cpu_icount_to_ns(sc->last_cpu_icount - cpu_icount);
69 sc->last_cpu_icount = cpu_icount;
70
71 if (sc->diff_clk > VM_CLOCK_ADVANCE) {
72#ifndef _WIN32
73 struct timespec sleep_delay, rem_delay;
74 sleep_delay.tv_sec = sc->diff_clk / 1000000000LL;
75 sleep_delay.tv_nsec = sc->diff_clk % 1000000000LL;
76 if (nanosleep(&sleep_delay, &rem_delay) < 0) {
77 sc->diff_clk = rem_delay.tv_sec * 1000000000LL + rem_delay.tv_nsec;
78 } else {
79 sc->diff_clk = 0;
80 }
81#else
82 Sleep(sc->diff_clk / SCALE_MS);
83 sc->diff_clk = 0;
84#endif
85 }
86}
87
88static void print_delay(const SyncClocks *sc)
89{
90 static float threshold_delay;
91 static int64_t last_realtime_clock;
92 static int nb_prints;
93
94 if (icount_align_option &&
95 sc->realtime_clock - last_realtime_clock >= MAX_DELAY_PRINT_RATE &&
96 nb_prints < MAX_NB_PRINTS) {
97 if ((-sc->diff_clk / (float)1000000000LL > threshold_delay) ||
98 (-sc->diff_clk / (float)1000000000LL <
99 (threshold_delay - THRESHOLD_REDUCE))) {
100 threshold_delay = (-sc->diff_clk / 1000000000LL) + 1;
101 printf("Warning: The guest is now late by %.1f to %.1f seconds\n",
102 threshold_delay - 1,
103 threshold_delay);
104 nb_prints++;
105 last_realtime_clock = sc->realtime_clock;
106 }
107 }
108}
109
110static void init_delay_params(SyncClocks *sc, CPUState *cpu)
111{
112 if (!icount_align_option) {
113 return;
114 }
115 sc->realtime_clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT);
116 sc->diff_clk = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - sc->realtime_clock;
117 sc->last_cpu_icount
118 = cpu->icount_extra + cpu_neg(cpu)->icount_decr.u16.low;
119 if (sc->diff_clk < max_delay) {
120 max_delay = sc->diff_clk;
121 }
122 if (sc->diff_clk > max_advance) {
123 max_advance = sc->diff_clk;
124 }
125
126 /* Print every 2s max if the guest is late. We limit the number
127 of printed messages to NB_PRINT_MAX(currently 100) */
128 print_delay(sc);
129}
130#else
131static void align_clocks(SyncClocks *sc, const CPUState *cpu)
132{
133}
134
135static void init_delay_params(SyncClocks *sc, const CPUState *cpu)
136{
137}
138#endif /* CONFIG USER ONLY */
139
140/* Execute a TB, and fix up the CPU state afterwards if necessary */
141static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, TranslationBlock *itb)
142{
143 CPUArchState *env = cpu->env_ptr;
144 uintptr_t ret;
145 TranslationBlock *last_tb;
146 int tb_exit;
147 uint8_t *tb_ptr = itb->tc.ptr;
148
149 qemu_log_mask_and_addr(CPU_LOG_EXEC, itb->pc,
150 "Trace %d: %p ["
151 TARGET_FMT_lx "/" TARGET_FMT_lx "/%#x] %s\n",
152 cpu->cpu_index, itb->tc.ptr,
153 itb->cs_base, itb->pc, itb->flags,
154 lookup_symbol(itb->pc));
155
156#if defined(DEBUG_DISAS)
157 if (qemu_loglevel_mask(CPU_LOG_TB_CPU)
158 && qemu_log_in_addr_range(itb->pc)) {
159 qemu_log_lock();
160 int flags = 0;
161 if (qemu_loglevel_mask(CPU_LOG_TB_FPU)) {
162 flags |= CPU_DUMP_FPU;
163 }
164#if defined(TARGET_I386)
165 flags |= CPU_DUMP_CCOP;
166#endif
167 log_cpu_state(cpu, flags);
168 qemu_log_unlock();
169 }
170#endif /* DEBUG_DISAS */
171
172 ret = tcg_qemu_tb_exec(env, tb_ptr);
173 cpu->can_do_io = 1;
174 last_tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK);
175 tb_exit = ret & TB_EXIT_MASK;
176 trace_exec_tb_exit(last_tb, tb_exit);
177
178 if (tb_exit > TB_EXIT_IDX1) {
179 /* We didn't start executing this TB (eg because the instruction
180 * counter hit zero); we must restore the guest PC to the address
181 * of the start of the TB.
182 */
183 CPUClass *cc = CPU_GET_CLASS(cpu);
184 qemu_log_mask_and_addr(CPU_LOG_EXEC, last_tb->pc,
185 "Stopped execution of TB chain before %p ["
186 TARGET_FMT_lx "] %s\n",
187 last_tb->tc.ptr, last_tb->pc,
188 lookup_symbol(last_tb->pc));
189 if (cc->synchronize_from_tb) {
190 cc->synchronize_from_tb(cpu, last_tb);
191 } else {
192 assert(cc->set_pc);
193 cc->set_pc(cpu, last_tb->pc);
194 }
195 }
196 return ret;
197}
198
199#ifndef CONFIG_USER_ONLY
200/* Execute the code without caching the generated code. An interpreter
201 could be used if available. */
202static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
203 TranslationBlock *orig_tb, bool ignore_icount)
204{
205 TranslationBlock *tb;
206 uint32_t cflags = curr_cflags() | CF_NOCACHE;
207
208 if (ignore_icount) {
209 cflags &= ~CF_USE_ICOUNT;
210 }
211
212 /* Should never happen.
213 We only end up here when an existing TB is too long. */
214 cflags |= MIN(max_cycles, CF_COUNT_MASK);
215
216 mmap_lock();
217 tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base,
218 orig_tb->flags, cflags);
219 tb->orig_tb = orig_tb;
220 mmap_unlock();
221
222 /* execute the generated code */
223 trace_exec_tb_nocache(tb, tb->pc);
224 cpu_tb_exec(cpu, tb);
225
226 mmap_lock();
227 tb_phys_invalidate(tb, -1);
228 mmap_unlock();
229 tcg_tb_remove(tb);
230}
231#endif
232
233void cpu_exec_step_atomic(CPUState *cpu)
234{
235 CPUClass *cc = CPU_GET_CLASS(cpu);
236 TranslationBlock *tb;
237 target_ulong cs_base, pc;
238 uint32_t flags;
239 uint32_t cflags = 1;
240 uint32_t cf_mask = cflags & CF_HASH_MASK;
241 /* volatile because we modify it between setjmp and longjmp */
242 volatile bool in_exclusive_region = false;
243
244 if (sigsetjmp(cpu->jmp_env, 0) == 0) {
245 tb = tb_lookup__cpu_state(cpu, &pc, &cs_base, &flags, cf_mask);
246 if (tb == NULL) {
247 mmap_lock();
248 tb = tb_gen_code(cpu, pc, cs_base, flags, cflags);
249 mmap_unlock();
250 }
251
252 start_exclusive();
253
254 /* Since we got here, we know that parallel_cpus must be true. */
255 parallel_cpus = false;
256 in_exclusive_region = true;
257 cc->cpu_exec_enter(cpu);
258 /* execute the generated code */
259 trace_exec_tb(tb, pc);
260 cpu_tb_exec(cpu, tb);
261 cc->cpu_exec_exit(cpu);
262 } else {
263 /*
264 * The mmap_lock is dropped by tb_gen_code if it runs out of
265 * memory.
266 */
267#ifndef CONFIG_SOFTMMU
268 tcg_debug_assert(!have_mmap_lock());
269#endif
270 if (qemu_mutex_iothread_locked()) {
271 qemu_mutex_unlock_iothread();
272 }
273 assert_no_pages_locked();
274 }
275
276 if (in_exclusive_region) {
277 /* We might longjump out of either the codegen or the
278 * execution, so must make sure we only end the exclusive
279 * region if we started it.
280 */
281 parallel_cpus = true;
282 end_exclusive();
283 }
284}
285
286struct tb_desc {
287 target_ulong pc;
288 target_ulong cs_base;
289 CPUArchState *env;
290 tb_page_addr_t phys_page1;
291 uint32_t flags;
292 uint32_t cf_mask;
293 uint32_t trace_vcpu_dstate;
294};
295
296static bool tb_lookup_cmp(const void *p, const void *d)
297{
298 const TranslationBlock *tb = p;
299 const struct tb_desc *desc = d;
300
301 if (tb->pc == desc->pc &&
302 tb->page_addr[0] == desc->phys_page1 &&
303 tb->cs_base == desc->cs_base &&
304 tb->flags == desc->flags &&
305 tb->trace_vcpu_dstate == desc->trace_vcpu_dstate &&
306 (tb_cflags(tb) & (CF_HASH_MASK | CF_INVALID)) == desc->cf_mask) {
307 /* check next page if needed */
308 if (tb->page_addr[1] == -1) {
309 return true;
310 } else {
311 tb_page_addr_t phys_page2;
312 target_ulong virt_page2;
313
314 virt_page2 = (desc->pc & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
315 phys_page2 = get_page_addr_code(desc->env, virt_page2);
316 if (tb->page_addr[1] == phys_page2) {
317 return true;
318 }
319 }
320 }
321 return false;
322}
323
324TranslationBlock *tb_htable_lookup(CPUState *cpu, target_ulong pc,
325 target_ulong cs_base, uint32_t flags,
326 uint32_t cf_mask)
327{
328 tb_page_addr_t phys_pc;
329 struct tb_desc desc;
330 uint32_t h;
331
332 desc.env = (CPUArchState *)cpu->env_ptr;
333 desc.cs_base = cs_base;
334 desc.flags = flags;
335 desc.cf_mask = cf_mask;
336 desc.trace_vcpu_dstate = *cpu->trace_dstate;
337 desc.pc = pc;
338 phys_pc = get_page_addr_code(desc.env, pc);
339 if (phys_pc == -1) {
340 return NULL;
341 }
342 desc.phys_page1 = phys_pc & TARGET_PAGE_MASK;
343 h = tb_hash_func(phys_pc, pc, flags, cf_mask, *cpu->trace_dstate);
344 return qht_lookup_custom(&tb_ctx.htable, &desc, h, tb_lookup_cmp);
345}
346
347void tb_set_jmp_target(TranslationBlock *tb, int n, uintptr_t addr)
348{
349 if (TCG_TARGET_HAS_direct_jump) {
350 uintptr_t offset = tb->jmp_target_arg[n];
351 uintptr_t tc_ptr = (uintptr_t)tb->tc.ptr;
352 tb_target_set_jmp_target(tc_ptr, tc_ptr + offset, addr);
353 } else {
354 tb->jmp_target_arg[n] = addr;
355 }
356}
357
358static inline void tb_add_jump(TranslationBlock *tb, int n,
359 TranslationBlock *tb_next)
360{
361 uintptr_t old;
362
363 assert(n < ARRAY_SIZE(tb->jmp_list_next));
364 qemu_spin_lock(&tb_next->jmp_lock);
365
366 /* make sure the destination TB is valid */
367 if (tb_next->cflags & CF_INVALID) {
368 goto out_unlock_next;
369 }
370 /* Atomically claim the jump destination slot only if it was NULL */
371 old = atomic_cmpxchg(&tb->jmp_dest[n], (uintptr_t)NULL, (uintptr_t)tb_next);
372 if (old) {
373 goto out_unlock_next;
374 }
375
376 /* patch the native jump address */
377 tb_set_jmp_target(tb, n, (uintptr_t)tb_next->tc.ptr);
378
379 /* add in TB jmp list */
380 tb->jmp_list_next[n] = tb_next->jmp_list_head;
381 tb_next->jmp_list_head = (uintptr_t)tb | n;
382
383 qemu_spin_unlock(&tb_next->jmp_lock);
384
385 qemu_log_mask_and_addr(CPU_LOG_EXEC, tb->pc,
386 "Linking TBs %p [" TARGET_FMT_lx
387 "] index %d -> %p [" TARGET_FMT_lx "]\n",
388 tb->tc.ptr, tb->pc, n,
389 tb_next->tc.ptr, tb_next->pc);
390 return;
391
392 out_unlock_next:
393 qemu_spin_unlock(&tb_next->jmp_lock);
394 return;
395}
396
397static inline TranslationBlock *tb_find(CPUState *cpu,
398 TranslationBlock *last_tb,
399 int tb_exit, uint32_t cf_mask)
400{
401 TranslationBlock *tb;
402 target_ulong cs_base, pc;
403 uint32_t flags;
404
405 tb = tb_lookup__cpu_state(cpu, &pc, &cs_base, &flags, cf_mask);
406 if (tb == NULL) {
407 mmap_lock();
408 tb = tb_gen_code(cpu, pc, cs_base, flags, cf_mask);
409 mmap_unlock();
410 /* We add the TB in the virtual pc hash table for the fast lookup */
411 atomic_set(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)], tb);
412 }
413#ifndef CONFIG_USER_ONLY
414 /* We don't take care of direct jumps when address mapping changes in
415 * system emulation. So it's not safe to make a direct jump to a TB
416 * spanning two pages because the mapping for the second page can change.
417 */
418 if (tb->page_addr[1] != -1) {
419 last_tb = NULL;
420 }
421#endif
422 /* See if we can patch the calling TB. */
423 if (last_tb) {
424 tb_add_jump(last_tb, tb_exit, tb);
425 }
426 return tb;
427}
428
429static inline bool cpu_handle_halt(CPUState *cpu)
430{
431 if (cpu->halted) {
432#if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
433 if ((cpu->interrupt_request & CPU_INTERRUPT_POLL)
434 && replay_interrupt()) {
435 X86CPU *x86_cpu = X86_CPU(cpu);
436 qemu_mutex_lock_iothread();
437 apic_poll_irq(x86_cpu->apic_state);
438 cpu_reset_interrupt(cpu, CPU_INTERRUPT_POLL);
439 qemu_mutex_unlock_iothread();
440 }
441#endif
442 if (!cpu_has_work(cpu)) {
443 return true;
444 }
445
446 cpu->halted = 0;
447 }
448
449 return false;
450}
451
452static inline void cpu_handle_debug_exception(CPUState *cpu)
453{
454 CPUClass *cc = CPU_GET_CLASS(cpu);
455 CPUWatchpoint *wp;
456
457 if (!cpu->watchpoint_hit) {
458 QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
459 wp->flags &= ~BP_WATCHPOINT_HIT;
460 }
461 }
462
463 cc->debug_excp_handler(cpu);
464}
465
466static inline bool cpu_handle_exception(CPUState *cpu, int *ret)
467{
468 if (cpu->exception_index < 0) {
469#ifndef CONFIG_USER_ONLY
470 if (replay_has_exception()
471 && cpu_neg(cpu)->icount_decr.u16.low + cpu->icount_extra == 0) {
472 /* try to cause an exception pending in the log */
473 cpu_exec_nocache(cpu, 1, tb_find(cpu, NULL, 0, curr_cflags()), true);
474 }
475#endif
476 if (cpu->exception_index < 0) {
477 return false;
478 }
479 }
480
481 if (cpu->exception_index >= EXCP_INTERRUPT) {
482 /* exit request from the cpu execution loop */
483 *ret = cpu->exception_index;
484 if (*ret == EXCP_DEBUG) {
485 cpu_handle_debug_exception(cpu);
486 }
487 cpu->exception_index = -1;
488 return true;
489 } else {
490#if defined(CONFIG_USER_ONLY)
491 /* if user mode only, we simulate a fake exception
492 which will be handled outside the cpu execution
493 loop */
494#if defined(TARGET_I386)
495 CPUClass *cc = CPU_GET_CLASS(cpu);
496 cc->do_interrupt(cpu);
497#endif
498 *ret = cpu->exception_index;
499 cpu->exception_index = -1;
500 return true;
501#else
502 if (replay_exception()) {
503 CPUClass *cc = CPU_GET_CLASS(cpu);
504 qemu_mutex_lock_iothread();
505 cc->do_interrupt(cpu);
506 qemu_mutex_unlock_iothread();
507 cpu->exception_index = -1;
508 } else if (!replay_has_interrupt()) {
509 /* give a chance to iothread in replay mode */
510 *ret = EXCP_INTERRUPT;
511 return true;
512 }
513#endif
514 }
515
516 return false;
517}
518
519static inline bool cpu_handle_interrupt(CPUState *cpu,
520 TranslationBlock **last_tb)
521{
522 CPUClass *cc = CPU_GET_CLASS(cpu);
523
524 /* Clear the interrupt flag now since we're processing
525 * cpu->interrupt_request and cpu->exit_request.
526 * Ensure zeroing happens before reading cpu->exit_request or
527 * cpu->interrupt_request (see also smp_wmb in cpu_exit())
528 */
529 atomic_mb_set(&cpu_neg(cpu)->icount_decr.u16.high, 0);
530
531 if (unlikely(atomic_read(&cpu->interrupt_request))) {
532 int interrupt_request;
533 qemu_mutex_lock_iothread();
534 interrupt_request = cpu->interrupt_request;
535 if (unlikely(cpu->singlestep_enabled & SSTEP_NOIRQ)) {
536 /* Mask out external interrupts for this step. */
537 interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK;
538 }
539 if (interrupt_request & CPU_INTERRUPT_DEBUG) {
540 cpu->interrupt_request &= ~CPU_INTERRUPT_DEBUG;
541 cpu->exception_index = EXCP_DEBUG;
542 qemu_mutex_unlock_iothread();
543 return true;
544 }
545 if (replay_mode == REPLAY_MODE_PLAY && !replay_has_interrupt()) {
546 /* Do nothing */
547 } else if (interrupt_request & CPU_INTERRUPT_HALT) {
548 replay_interrupt();
549 cpu->interrupt_request &= ~CPU_INTERRUPT_HALT;
550 cpu->halted = 1;
551 cpu->exception_index = EXCP_HLT;
552 qemu_mutex_unlock_iothread();
553 return true;
554 }
555#if defined(TARGET_I386)
556 else if (interrupt_request & CPU_INTERRUPT_INIT) {
557 X86CPU *x86_cpu = X86_CPU(cpu);
558 CPUArchState *env = &x86_cpu->env;
559 replay_interrupt();
560 cpu_svm_check_intercept_param(env, SVM_EXIT_INIT, 0, 0);
561 do_cpu_init(x86_cpu);
562 cpu->exception_index = EXCP_HALTED;
563 qemu_mutex_unlock_iothread();
564 return true;
565 }
566#else
567 else if (interrupt_request & CPU_INTERRUPT_RESET) {
568 replay_interrupt();
569 cpu_reset(cpu);
570 qemu_mutex_unlock_iothread();
571 return true;
572 }
573#endif
574 /* The target hook has 3 exit conditions:
575 False when the interrupt isn't processed,
576 True when it is, and we should restart on a new TB,
577 and via longjmp via cpu_loop_exit. */
578 else {
579 if (cc->cpu_exec_interrupt(cpu, interrupt_request)) {
580 replay_interrupt();
581 cpu->exception_index = -1;
582 *last_tb = NULL;
583 }
584 /* The target hook may have updated the 'cpu->interrupt_request';
585 * reload the 'interrupt_request' value */
586 interrupt_request = cpu->interrupt_request;
587 }
588 if (interrupt_request & CPU_INTERRUPT_EXITTB) {
589 cpu->interrupt_request &= ~CPU_INTERRUPT_EXITTB;
590 /* ensure that no TB jump will be modified as
591 the program flow was changed */
592 *last_tb = NULL;
593 }
594
595 /* If we exit via cpu_loop_exit/longjmp it is reset in cpu_exec */
596 qemu_mutex_unlock_iothread();
597 }
598
599 /* Finally, check if we need to exit to the main loop. */
600 if (unlikely(atomic_read(&cpu->exit_request))
601 || (use_icount
602 && cpu_neg(cpu)->icount_decr.u16.low + cpu->icount_extra == 0)) {
603 atomic_set(&cpu->exit_request, 0);
604 if (cpu->exception_index == -1) {
605 cpu->exception_index = EXCP_INTERRUPT;
606 }
607 return true;
608 }
609
610 return false;
611}
612
613static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
614 TranslationBlock **last_tb, int *tb_exit)
615{
616 uintptr_t ret;
617 int32_t insns_left;
618
619 trace_exec_tb(tb, tb->pc);
620 ret = cpu_tb_exec(cpu, tb);
621 tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK);
622 *tb_exit = ret & TB_EXIT_MASK;
623 if (*tb_exit != TB_EXIT_REQUESTED) {
624 *last_tb = tb;
625 return;
626 }
627
628 *last_tb = NULL;
629 insns_left = atomic_read(&cpu_neg(cpu)->icount_decr.u32);
630 if (insns_left < 0) {
631 /* Something asked us to stop executing chained TBs; just
632 * continue round the main loop. Whatever requested the exit
633 * will also have set something else (eg exit_request or
634 * interrupt_request) which will be handled by
635 * cpu_handle_interrupt. cpu_handle_interrupt will also
636 * clear cpu->icount_decr.u16.high.
637 */
638 return;
639 }
640
641 /* Instruction counter expired. */
642 assert(use_icount);
643#ifndef CONFIG_USER_ONLY
644 /* Ensure global icount has gone forward */
645 cpu_update_icount(cpu);
646 /* Refill decrementer and continue execution. */
647 insns_left = MIN(0xffff, cpu->icount_budget);
648 cpu_neg(cpu)->icount_decr.u16.low = insns_left;
649 cpu->icount_extra = cpu->icount_budget - insns_left;
650 if (!cpu->icount_extra) {
651 /* Execute any remaining instructions, then let the main loop
652 * handle the next event.
653 */
654 if (insns_left > 0) {
655 cpu_exec_nocache(cpu, insns_left, tb, false);
656 }
657 }
658#endif
659}
660
661/* main execution loop */
662
663int cpu_exec(CPUState *cpu)
664{
665 CPUClass *cc = CPU_GET_CLASS(cpu);
666 int ret;
667 SyncClocks sc = { 0 };
668
669 /* replay_interrupt may need current_cpu */
670 current_cpu = cpu;
671
672 if (cpu_handle_halt(cpu)) {
673 return EXCP_HALTED;
674 }
675
676 rcu_read_lock();
677
678 cc->cpu_exec_enter(cpu);
679
680 /* Calculate difference between guest clock and host clock.
681 * This delay includes the delay of the last cycle, so
682 * what we have to do is sleep until it is 0. As for the
683 * advance/delay we gain here, we try to fix it next time.
684 */
685 init_delay_params(&sc, cpu);
686
687 /* prepare setjmp context for exception handling */
688 if (sigsetjmp(cpu->jmp_env, 0) != 0) {
689#if defined(__clang__) || !QEMU_GNUC_PREREQ(4, 6)
690 /* Some compilers wrongly smash all local variables after
691 * siglongjmp. There were bug reports for gcc 4.5.0 and clang.
692 * Reload essential local variables here for those compilers.
693 * Newer versions of gcc would complain about this code (-Wclobbered). */
694 cpu = current_cpu;
695 cc = CPU_GET_CLASS(cpu);
696#else /* buggy compiler */
697 /* Assert that the compiler does not smash local variables. */
698 g_assert(cpu == current_cpu);
699 g_assert(cc == CPU_GET_CLASS(cpu));
700#endif /* buggy compiler */
701#ifndef CONFIG_SOFTMMU
702 tcg_debug_assert(!have_mmap_lock());
703#endif
704 if (qemu_mutex_iothread_locked()) {
705 qemu_mutex_unlock_iothread();
706 }
707 assert_no_pages_locked();
708 }
709
710 /* if an exception is pending, we execute it here */
711 while (!cpu_handle_exception(cpu, &ret)) {
712 TranslationBlock *last_tb = NULL;
713 int tb_exit = 0;
714
715 while (!cpu_handle_interrupt(cpu, &last_tb)) {
716 uint32_t cflags = cpu->cflags_next_tb;
717 TranslationBlock *tb;
718
719 /* When requested, use an exact setting for cflags for the next
720 execution. This is used for icount, precise smc, and stop-
721 after-access watchpoints. Since this request should never
722 have CF_INVALID set, -1 is a convenient invalid value that
723 does not require tcg headers for cpu_common_reset. */
724 if (cflags == -1) {
725 cflags = curr_cflags();
726 } else {
727 cpu->cflags_next_tb = -1;
728 }
729
730 tb = tb_find(cpu, last_tb, tb_exit, cflags);
731 cpu_loop_exec_tb(cpu, tb, &last_tb, &tb_exit);
732 /* Try to align the host and virtual clocks
733 if the guest is in advance */
734 align_clocks(&sc, cpu);
735 }
736 }
737
738 cc->cpu_exec_exit(cpu);
739 rcu_read_unlock();
740
741 return ret;
742}
743