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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.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 [" TARGET_FMT_lx "] %s\n", | |
147 | itb->tc_ptr, itb->pc, lookup_symbol(itb->pc)); | |
148 | ||
149 | #if defined(DEBUG_DISAS) | |
150 | if (qemu_loglevel_mask(CPU_LOG_TB_CPU)) { | |
151 | #if defined(TARGET_I386) | |
152 | log_cpu_state(cpu, CPU_DUMP_CCOP); | |
153 | #elif defined(TARGET_M68K) | |
154 | /* ??? Should not modify env state for dumping. */ | |
155 | cpu_m68k_flush_flags(env, env->cc_op); | |
156 | env->cc_op = CC_OP_FLAGS; | |
157 | env->sr = (env->sr & 0xffe0) | env->cc_dest | (env->cc_x << 4); | |
158 | log_cpu_state(cpu, 0); | |
159 | #else | |
160 | log_cpu_state(cpu, 0); | |
161 | #endif | |
162 | } | |
163 | #endif /* DEBUG_DISAS */ | |
164 | ||
165 | cpu->can_do_io = !use_icount; | |
166 | ret = tcg_qemu_tb_exec(env, tb_ptr); | |
167 | cpu->can_do_io = 1; | |
168 | last_tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK); | |
169 | tb_exit = ret & TB_EXIT_MASK; | |
170 | trace_exec_tb_exit(last_tb, tb_exit); | |
171 | ||
172 | if (tb_exit > TB_EXIT_IDX1) { | |
173 | /* We didn't start executing this TB (eg because the instruction | |
174 | * counter hit zero); we must restore the guest PC to the address | |
175 | * of the start of the TB. | |
176 | */ | |
177 | CPUClass *cc = CPU_GET_CLASS(cpu); | |
178 | qemu_log_mask_and_addr(CPU_LOG_EXEC, last_tb->pc, | |
179 | "Stopped execution of TB chain before %p [" | |
180 | TARGET_FMT_lx "] %s\n", | |
181 | last_tb->tc_ptr, last_tb->pc, | |
182 | lookup_symbol(last_tb->pc)); | |
183 | if (cc->synchronize_from_tb) { | |
184 | cc->synchronize_from_tb(cpu, last_tb); | |
185 | } else { | |
186 | assert(cc->set_pc); | |
187 | cc->set_pc(cpu, last_tb->pc); | |
188 | } | |
189 | } | |
190 | if (tb_exit == TB_EXIT_REQUESTED) { | |
191 | /* We were asked to stop executing TBs (probably a pending | |
192 | * interrupt. We've now stopped, so clear the flag. | |
193 | */ | |
194 | cpu->tcg_exit_req = 0; | |
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. */ | |
202 | static void cpu_exec_nocache(CPUState *cpu, int max_cycles, | |
203 | TranslationBlock *orig_tb, bool ignore_icount) | |
204 | { | |
205 | TranslationBlock *tb; | |
206 | bool old_tb_flushed; | |
207 | ||
208 | /* Should never happen. | |
209 | We only end up here when an existing TB is too long. */ | |
210 | if (max_cycles > CF_COUNT_MASK) | |
211 | max_cycles = CF_COUNT_MASK; | |
212 | ||
213 | old_tb_flushed = cpu->tb_flushed; | |
214 | cpu->tb_flushed = false; | |
215 | tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base, orig_tb->flags, | |
216 | max_cycles | CF_NOCACHE | |
217 | | (ignore_icount ? CF_IGNORE_ICOUNT : 0)); | |
218 | tb->orig_tb = cpu->tb_flushed ? NULL : orig_tb; | |
219 | cpu->tb_flushed |= old_tb_flushed; | |
220 | /* execute the generated code */ | |
221 | trace_exec_tb_nocache(tb, tb->pc); | |
222 | cpu_tb_exec(cpu, tb); | |
223 | tb_phys_invalidate(tb, -1); | |
224 | tb_free(tb); | |
225 | } | |
226 | #endif | |
227 | ||
228 | struct tb_desc { | |
229 | target_ulong pc; | |
230 | target_ulong cs_base; | |
231 | CPUArchState *env; | |
232 | tb_page_addr_t phys_page1; | |
233 | uint32_t flags; | |
234 | }; | |
235 | ||
236 | static bool tb_cmp(const void *p, const void *d) | |
237 | { | |
238 | const TranslationBlock *tb = p; | |
239 | const struct tb_desc *desc = d; | |
240 | ||
241 | if (tb->pc == desc->pc && | |
242 | tb->page_addr[0] == desc->phys_page1 && | |
243 | tb->cs_base == desc->cs_base && | |
244 | tb->flags == desc->flags) { | |
245 | /* check next page if needed */ | |
246 | if (tb->page_addr[1] == -1) { | |
247 | return true; | |
248 | } else { | |
249 | tb_page_addr_t phys_page2; | |
250 | target_ulong virt_page2; | |
251 | ||
252 | virt_page2 = (desc->pc & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE; | |
253 | phys_page2 = get_page_addr_code(desc->env, virt_page2); | |
254 | if (tb->page_addr[1] == phys_page2) { | |
255 | return true; | |
256 | } | |
257 | } | |
258 | } | |
259 | return false; | |
260 | } | |
261 | ||
262 | static TranslationBlock *tb_find_physical(CPUState *cpu, | |
263 | target_ulong pc, | |
264 | target_ulong cs_base, | |
265 | uint32_t flags) | |
266 | { | |
267 | tb_page_addr_t phys_pc; | |
268 | struct tb_desc desc; | |
269 | uint32_t h; | |
270 | ||
271 | desc.env = (CPUArchState *)cpu->env_ptr; | |
272 | desc.cs_base = cs_base; | |
273 | desc.flags = flags; | |
274 | desc.pc = pc; | |
275 | phys_pc = get_page_addr_code(desc.env, pc); | |
276 | desc.phys_page1 = phys_pc & TARGET_PAGE_MASK; | |
277 | h = tb_hash_func(phys_pc, pc, flags); | |
278 | return qht_lookup(&tcg_ctx.tb_ctx.htable, tb_cmp, &desc, h); | |
279 | } | |
280 | ||
281 | static TranslationBlock *tb_find_slow(CPUState *cpu, | |
282 | target_ulong pc, | |
283 | target_ulong cs_base, | |
284 | uint32_t flags) | |
285 | { | |
286 | TranslationBlock *tb; | |
287 | ||
288 | tb = tb_find_physical(cpu, pc, cs_base, flags); | |
289 | if (tb) { | |
290 | goto found; | |
291 | } | |
292 | ||
293 | #ifdef CONFIG_USER_ONLY | |
294 | /* mmap_lock is needed by tb_gen_code, and mmap_lock must be | |
295 | * taken outside tb_lock. Since we're momentarily dropping | |
296 | * tb_lock, there's a chance that our desired tb has been | |
297 | * translated. | |
298 | */ | |
299 | tb_unlock(); | |
300 | mmap_lock(); | |
301 | tb_lock(); | |
302 | tb = tb_find_physical(cpu, pc, cs_base, flags); | |
303 | if (tb) { | |
304 | mmap_unlock(); | |
305 | goto found; | |
306 | } | |
307 | #endif | |
308 | ||
309 | /* if no translated code available, then translate it now */ | |
310 | tb = tb_gen_code(cpu, pc, cs_base, flags, 0); | |
311 | ||
312 | #ifdef CONFIG_USER_ONLY | |
313 | mmap_unlock(); | |
314 | #endif | |
315 | ||
316 | found: | |
317 | /* we add the TB in the virtual pc hash table */ | |
318 | cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)] = tb; | |
319 | return tb; | |
320 | } | |
321 | ||
322 | static inline TranslationBlock *tb_find_fast(CPUState *cpu, | |
323 | TranslationBlock **last_tb, | |
324 | int tb_exit) | |
325 | { | |
326 | CPUArchState *env = (CPUArchState *)cpu->env_ptr; | |
327 | TranslationBlock *tb; | |
328 | target_ulong cs_base, pc; | |
329 | uint32_t flags; | |
330 | ||
331 | /* we record a subset of the CPU state. It will | |
332 | always be the same before a given translated block | |
333 | is executed. */ | |
334 | cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); | |
335 | tb_lock(); | |
336 | tb = cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)]; | |
337 | if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base || | |
338 | tb->flags != flags)) { | |
339 | tb = tb_find_slow(cpu, pc, cs_base, flags); | |
340 | } | |
341 | if (cpu->tb_flushed) { | |
342 | /* Ensure that no TB jump will be modified as the | |
343 | * translation buffer has been flushed. | |
344 | */ | |
345 | *last_tb = NULL; | |
346 | cpu->tb_flushed = false; | |
347 | } | |
348 | #ifndef CONFIG_USER_ONLY | |
349 | /* We don't take care of direct jumps when address mapping changes in | |
350 | * system emulation. So it's not safe to make a direct jump to a TB | |
351 | * spanning two pages because the mapping for the second page can change. | |
352 | */ | |
353 | if (tb->page_addr[1] != -1) { | |
354 | *last_tb = NULL; | |
355 | } | |
356 | #endif | |
357 | /* See if we can patch the calling TB. */ | |
358 | if (*last_tb && !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) { | |
359 | tb_add_jump(*last_tb, tb_exit, tb); | |
360 | } | |
361 | tb_unlock(); | |
362 | return tb; | |
363 | } | |
364 | ||
365 | static inline bool cpu_handle_halt(CPUState *cpu) | |
366 | { | |
367 | if (cpu->halted) { | |
368 | #if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY) | |
369 | if ((cpu->interrupt_request & CPU_INTERRUPT_POLL) | |
370 | && replay_interrupt()) { | |
371 | X86CPU *x86_cpu = X86_CPU(cpu); | |
372 | apic_poll_irq(x86_cpu->apic_state); | |
373 | cpu_reset_interrupt(cpu, CPU_INTERRUPT_POLL); | |
374 | } | |
375 | #endif | |
376 | if (!cpu_has_work(cpu)) { | |
377 | current_cpu = NULL; | |
378 | return true; | |
379 | } | |
380 | ||
381 | cpu->halted = 0; | |
382 | } | |
383 | ||
384 | return false; | |
385 | } | |
386 | ||
387 | static inline void cpu_handle_debug_exception(CPUState *cpu) | |
388 | { | |
389 | CPUClass *cc = CPU_GET_CLASS(cpu); | |
390 | CPUWatchpoint *wp; | |
391 | ||
392 | if (!cpu->watchpoint_hit) { | |
393 | QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) { | |
394 | wp->flags &= ~BP_WATCHPOINT_HIT; | |
395 | } | |
396 | } | |
397 | ||
398 | cc->debug_excp_handler(cpu); | |
399 | } | |
400 | ||
401 | static inline bool cpu_handle_exception(CPUState *cpu, int *ret) | |
402 | { | |
403 | if (cpu->exception_index >= 0) { | |
404 | if (cpu->exception_index >= EXCP_INTERRUPT) { | |
405 | /* exit request from the cpu execution loop */ | |
406 | *ret = cpu->exception_index; | |
407 | if (*ret == EXCP_DEBUG) { | |
408 | cpu_handle_debug_exception(cpu); | |
409 | } | |
410 | cpu->exception_index = -1; | |
411 | return true; | |
412 | } else { | |
413 | #if defined(CONFIG_USER_ONLY) | |
414 | /* if user mode only, we simulate a fake exception | |
415 | which will be handled outside the cpu execution | |
416 | loop */ | |
417 | #if defined(TARGET_I386) | |
418 | CPUClass *cc = CPU_GET_CLASS(cpu); | |
419 | cc->do_interrupt(cpu); | |
420 | #endif | |
421 | *ret = cpu->exception_index; | |
422 | cpu->exception_index = -1; | |
423 | return true; | |
424 | #else | |
425 | if (replay_exception()) { | |
426 | CPUClass *cc = CPU_GET_CLASS(cpu); | |
427 | cc->do_interrupt(cpu); | |
428 | cpu->exception_index = -1; | |
429 | } else if (!replay_has_interrupt()) { | |
430 | /* give a chance to iothread in replay mode */ | |
431 | *ret = EXCP_INTERRUPT; | |
432 | return true; | |
433 | } | |
434 | #endif | |
435 | } | |
436 | #ifndef CONFIG_USER_ONLY | |
437 | } else if (replay_has_exception() | |
438 | && cpu->icount_decr.u16.low + cpu->icount_extra == 0) { | |
439 | /* try to cause an exception pending in the log */ | |
440 | TranslationBlock *last_tb = NULL; /* Avoid chaining TBs */ | |
441 | cpu_exec_nocache(cpu, 1, tb_find_fast(cpu, &last_tb, 0), true); | |
442 | *ret = -1; | |
443 | return true; | |
444 | #endif | |
445 | } | |
446 | ||
447 | return false; | |
448 | } | |
449 | ||
450 | static inline void cpu_handle_interrupt(CPUState *cpu, | |
451 | TranslationBlock **last_tb) | |
452 | { | |
453 | CPUClass *cc = CPU_GET_CLASS(cpu); | |
454 | int interrupt_request = cpu->interrupt_request; | |
455 | ||
456 | if (unlikely(interrupt_request)) { | |
457 | if (unlikely(cpu->singlestep_enabled & SSTEP_NOIRQ)) { | |
458 | /* Mask out external interrupts for this step. */ | |
459 | interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK; | |
460 | } | |
461 | if (interrupt_request & CPU_INTERRUPT_DEBUG) { | |
462 | cpu->interrupt_request &= ~CPU_INTERRUPT_DEBUG; | |
463 | cpu->exception_index = EXCP_DEBUG; | |
464 | cpu_loop_exit(cpu); | |
465 | } | |
466 | if (replay_mode == REPLAY_MODE_PLAY && !replay_has_interrupt()) { | |
467 | /* Do nothing */ | |
468 | } else if (interrupt_request & CPU_INTERRUPT_HALT) { | |
469 | replay_interrupt(); | |
470 | cpu->interrupt_request &= ~CPU_INTERRUPT_HALT; | |
471 | cpu->halted = 1; | |
472 | cpu->exception_index = EXCP_HLT; | |
473 | cpu_loop_exit(cpu); | |
474 | } | |
475 | #if defined(TARGET_I386) | |
476 | else if (interrupt_request & CPU_INTERRUPT_INIT) { | |
477 | X86CPU *x86_cpu = X86_CPU(cpu); | |
478 | CPUArchState *env = &x86_cpu->env; | |
479 | replay_interrupt(); | |
480 | cpu_svm_check_intercept_param(env, SVM_EXIT_INIT, 0); | |
481 | do_cpu_init(x86_cpu); | |
482 | cpu->exception_index = EXCP_HALTED; | |
483 | cpu_loop_exit(cpu); | |
484 | } | |
485 | #else | |
486 | else if (interrupt_request & CPU_INTERRUPT_RESET) { | |
487 | replay_interrupt(); | |
488 | cpu_reset(cpu); | |
489 | cpu_loop_exit(cpu); | |
490 | } | |
491 | #endif | |
492 | /* The target hook has 3 exit conditions: | |
493 | False when the interrupt isn't processed, | |
494 | True when it is, and we should restart on a new TB, | |
495 | and via longjmp via cpu_loop_exit. */ | |
496 | else { | |
497 | replay_interrupt(); | |
498 | if (cc->cpu_exec_interrupt(cpu, interrupt_request)) { | |
499 | *last_tb = NULL; | |
500 | } | |
501 | /* The target hook may have updated the 'cpu->interrupt_request'; | |
502 | * reload the 'interrupt_request' value */ | |
503 | interrupt_request = cpu->interrupt_request; | |
504 | } | |
505 | if (interrupt_request & CPU_INTERRUPT_EXITTB) { | |
506 | cpu->interrupt_request &= ~CPU_INTERRUPT_EXITTB; | |
507 | /* ensure that no TB jump will be modified as | |
508 | the program flow was changed */ | |
509 | *last_tb = NULL; | |
510 | } | |
511 | } | |
512 | if (unlikely(cpu->exit_request || replay_has_interrupt())) { | |
513 | cpu->exit_request = 0; | |
514 | cpu->exception_index = EXCP_INTERRUPT; | |
515 | cpu_loop_exit(cpu); | |
516 | } | |
517 | } | |
518 | ||
519 | static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb, | |
520 | TranslationBlock **last_tb, int *tb_exit, | |
521 | SyncClocks *sc) | |
522 | { | |
523 | uintptr_t ret; | |
524 | ||
525 | if (unlikely(cpu->exit_request)) { | |
526 | return; | |
527 | } | |
528 | ||
529 | trace_exec_tb(tb, tb->pc); | |
530 | ret = cpu_tb_exec(cpu, tb); | |
531 | *last_tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK); | |
532 | *tb_exit = ret & TB_EXIT_MASK; | |
533 | switch (*tb_exit) { | |
534 | case TB_EXIT_REQUESTED: | |
535 | /* Something asked us to stop executing | |
536 | * chained TBs; just continue round the main | |
537 | * loop. Whatever requested the exit will also | |
538 | * have set something else (eg exit_request or | |
539 | * interrupt_request) which we will handle | |
540 | * next time around the loop. But we need to | |
541 | * ensure the tcg_exit_req read in generated code | |
542 | * comes before the next read of cpu->exit_request | |
543 | * or cpu->interrupt_request. | |
544 | */ | |
545 | smp_rmb(); | |
546 | *last_tb = NULL; | |
547 | break; | |
548 | case TB_EXIT_ICOUNT_EXPIRED: | |
549 | { | |
550 | /* Instruction counter expired. */ | |
551 | #ifdef CONFIG_USER_ONLY | |
552 | abort(); | |
553 | #else | |
554 | int insns_left = cpu->icount_decr.u32; | |
555 | if (cpu->icount_extra && insns_left >= 0) { | |
556 | /* Refill decrementer and continue execution. */ | |
557 | cpu->icount_extra += insns_left; | |
558 | insns_left = MIN(0xffff, cpu->icount_extra); | |
559 | cpu->icount_extra -= insns_left; | |
560 | cpu->icount_decr.u16.low = insns_left; | |
561 | } else { | |
562 | if (insns_left > 0) { | |
563 | /* Execute remaining instructions. */ | |
564 | cpu_exec_nocache(cpu, insns_left, *last_tb, false); | |
565 | align_clocks(sc, cpu); | |
566 | } | |
567 | cpu->exception_index = EXCP_INTERRUPT; | |
568 | *last_tb = NULL; | |
569 | cpu_loop_exit(cpu); | |
570 | } | |
571 | break; | |
572 | #endif | |
573 | } | |
574 | default: | |
575 | break; | |
576 | } | |
577 | } | |
578 | ||
579 | /* main execution loop */ | |
580 | ||
581 | int cpu_exec(CPUState *cpu) | |
582 | { | |
583 | CPUClass *cc = CPU_GET_CLASS(cpu); | |
584 | int ret; | |
585 | SyncClocks sc; | |
586 | ||
587 | /* replay_interrupt may need current_cpu */ | |
588 | current_cpu = cpu; | |
589 | ||
590 | if (cpu_handle_halt(cpu)) { | |
591 | return EXCP_HALTED; | |
592 | } | |
593 | ||
594 | atomic_mb_set(&tcg_current_cpu, cpu); | |
595 | rcu_read_lock(); | |
596 | ||
597 | if (unlikely(atomic_mb_read(&exit_request))) { | |
598 | cpu->exit_request = 1; | |
599 | } | |
600 | ||
601 | cc->cpu_exec_enter(cpu); | |
602 | ||
603 | /* Calculate difference between guest clock and host clock. | |
604 | * This delay includes the delay of the last cycle, so | |
605 | * what we have to do is sleep until it is 0. As for the | |
606 | * advance/delay we gain here, we try to fix it next time. | |
607 | */ | |
608 | init_delay_params(&sc, cpu); | |
609 | ||
610 | for(;;) { | |
611 | /* prepare setjmp context for exception handling */ | |
612 | if (sigsetjmp(cpu->jmp_env, 0) == 0) { | |
613 | TranslationBlock *tb, *last_tb = NULL; | |
614 | int tb_exit = 0; | |
615 | ||
616 | /* if an exception is pending, we execute it here */ | |
617 | if (cpu_handle_exception(cpu, &ret)) { | |
618 | break; | |
619 | } | |
620 | ||
621 | cpu->tb_flushed = false; /* reset before first TB lookup */ | |
622 | for(;;) { | |
623 | cpu_handle_interrupt(cpu, &last_tb); | |
624 | tb = tb_find_fast(cpu, &last_tb, tb_exit); | |
625 | cpu_loop_exec_tb(cpu, tb, &last_tb, &tb_exit, &sc); | |
626 | /* Try to align the host and virtual clocks | |
627 | if the guest is in advance */ | |
628 | align_clocks(&sc, cpu); | |
629 | } /* for(;;) */ | |
630 | } else { | |
631 | #if defined(__clang__) || !QEMU_GNUC_PREREQ(4, 6) | |
632 | /* Some compilers wrongly smash all local variables after | |
633 | * siglongjmp. There were bug reports for gcc 4.5.0 and clang. | |
634 | * Reload essential local variables here for those compilers. | |
635 | * Newer versions of gcc would complain about this code (-Wclobbered). */ | |
636 | cpu = current_cpu; | |
637 | cc = CPU_GET_CLASS(cpu); | |
638 | #else /* buggy compiler */ | |
639 | /* Assert that the compiler does not smash local variables. */ | |
640 | g_assert(cpu == current_cpu); | |
641 | g_assert(cc == CPU_GET_CLASS(cpu)); | |
642 | #endif /* buggy compiler */ | |
643 | cpu->can_do_io = 1; | |
644 | tb_lock_reset(); | |
645 | } | |
646 | } /* for(;;) */ | |
647 | ||
648 | cc->cpu_exec_exit(cpu); | |
649 | rcu_read_unlock(); | |
650 | ||
651 | /* fail safe : never use current_cpu outside cpu_exec() */ | |
652 | current_cpu = NULL; | |
653 | ||
654 | /* Does not need atomic_mb_set because a spurious wakeup is okay. */ | |
655 | atomic_set(&tcg_current_cpu, NULL); | |
656 | return ret; | |
657 | } |