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