Merge remote-tracking branch 'remotes/armbru/tags/for-upstream' into staging
[qemu.git] / 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 "trace.h"
22 #include "disas/disas.h"
23 #include "tcg.h"
24 #include "qemu/atomic.h"
25 #include "sysemu/qtest.h"
26 #include "qemu/timer.h"
27
28 /* -icount align implementation. */
29
30 typedef struct SyncClocks {
31 int64_t diff_clk;
32 int64_t last_cpu_icount;
33 int64_t realtime_clock;
34 } SyncClocks;
35
36 #if !defined(CONFIG_USER_ONLY)
37 /* Allow the guest to have a max 3ms advance.
38 * The difference between the 2 clocks could therefore
39 * oscillate around 0.
40 */
41 #define VM_CLOCK_ADVANCE 3000000
42 #define THRESHOLD_REDUCE 1.5
43 #define MAX_DELAY_PRINT_RATE 2000000000LL
44 #define MAX_NB_PRINTS 100
45
46 static void align_clocks(SyncClocks *sc, const CPUState *cpu)
47 {
48 int64_t cpu_icount;
49
50 if (!icount_align_option) {
51 return;
52 }
53
54 cpu_icount = cpu->icount_extra + cpu->icount_decr.u16.low;
55 sc->diff_clk += cpu_icount_to_ns(sc->last_cpu_icount - cpu_icount);
56 sc->last_cpu_icount = cpu_icount;
57
58 if (sc->diff_clk > VM_CLOCK_ADVANCE) {
59 #ifndef _WIN32
60 struct timespec sleep_delay, rem_delay;
61 sleep_delay.tv_sec = sc->diff_clk / 1000000000LL;
62 sleep_delay.tv_nsec = sc->diff_clk % 1000000000LL;
63 if (nanosleep(&sleep_delay, &rem_delay) < 0) {
64 sc->diff_clk -= (sleep_delay.tv_sec - rem_delay.tv_sec) * 1000000000LL;
65 sc->diff_clk -= sleep_delay.tv_nsec - rem_delay.tv_nsec;
66 } else {
67 sc->diff_clk = 0;
68 }
69 #else
70 Sleep(sc->diff_clk / SCALE_MS);
71 sc->diff_clk = 0;
72 #endif
73 }
74 }
75
76 static void print_delay(const SyncClocks *sc)
77 {
78 static float threshold_delay;
79 static int64_t last_realtime_clock;
80 static int nb_prints;
81
82 if (icount_align_option &&
83 sc->realtime_clock - last_realtime_clock >= MAX_DELAY_PRINT_RATE &&
84 nb_prints < MAX_NB_PRINTS) {
85 if ((-sc->diff_clk / (float)1000000000LL > threshold_delay) ||
86 (-sc->diff_clk / (float)1000000000LL <
87 (threshold_delay - THRESHOLD_REDUCE))) {
88 threshold_delay = (-sc->diff_clk / 1000000000LL) + 1;
89 printf("Warning: The guest is now late by %.1f to %.1f seconds\n",
90 threshold_delay - 1,
91 threshold_delay);
92 nb_prints++;
93 last_realtime_clock = sc->realtime_clock;
94 }
95 }
96 }
97
98 static void init_delay_params(SyncClocks *sc,
99 const CPUState *cpu)
100 {
101 if (!icount_align_option) {
102 return;
103 }
104 sc->realtime_clock = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
105 sc->diff_clk = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) -
106 sc->realtime_clock +
107 cpu_get_clock_offset();
108 sc->last_cpu_icount = cpu->icount_extra + cpu->icount_decr.u16.low;
109 if (sc->diff_clk < max_delay) {
110 max_delay = sc->diff_clk;
111 }
112 if (sc->diff_clk > max_advance) {
113 max_advance = sc->diff_clk;
114 }
115
116 /* Print every 2s max if the guest is late. We limit the number
117 of printed messages to NB_PRINT_MAX(currently 100) */
118 print_delay(sc);
119 }
120 #else
121 static void align_clocks(SyncClocks *sc, const CPUState *cpu)
122 {
123 }
124
125 static void init_delay_params(SyncClocks *sc, const CPUState *cpu)
126 {
127 }
128 #endif /* CONFIG USER ONLY */
129
130 void cpu_loop_exit(CPUState *cpu)
131 {
132 cpu->current_tb = NULL;
133 siglongjmp(cpu->jmp_env, 1);
134 }
135
136 /* exit the current TB from a signal handler. The host registers are
137 restored in a state compatible with the CPU emulator
138 */
139 #if defined(CONFIG_SOFTMMU)
140 void cpu_resume_from_signal(CPUState *cpu, void *puc)
141 {
142 /* XXX: restore cpu registers saved in host registers */
143
144 cpu->exception_index = -1;
145 siglongjmp(cpu->jmp_env, 1);
146 }
147 #endif
148
149 /* Execute a TB, and fix up the CPU state afterwards if necessary */
150 static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, uint8_t *tb_ptr)
151 {
152 CPUArchState *env = cpu->env_ptr;
153 uintptr_t next_tb;
154
155 #if defined(DEBUG_DISAS)
156 if (qemu_loglevel_mask(CPU_LOG_TB_CPU)) {
157 #if defined(TARGET_I386)
158 log_cpu_state(cpu, CPU_DUMP_CCOP);
159 #elif defined(TARGET_M68K)
160 /* ??? Should not modify env state for dumping. */
161 cpu_m68k_flush_flags(env, env->cc_op);
162 env->cc_op = CC_OP_FLAGS;
163 env->sr = (env->sr & 0xffe0) | env->cc_dest | (env->cc_x << 4);
164 log_cpu_state(cpu, 0);
165 #else
166 log_cpu_state(cpu, 0);
167 #endif
168 }
169 #endif /* DEBUG_DISAS */
170
171 next_tb = tcg_qemu_tb_exec(env, tb_ptr);
172 trace_exec_tb_exit((void *) (next_tb & ~TB_EXIT_MASK),
173 next_tb & TB_EXIT_MASK);
174
175 if ((next_tb & TB_EXIT_MASK) > TB_EXIT_IDX1) {
176 /* We didn't start executing this TB (eg because the instruction
177 * counter hit zero); we must restore the guest PC to the address
178 * of the start of the TB.
179 */
180 CPUClass *cc = CPU_GET_CLASS(cpu);
181 TranslationBlock *tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
182 if (cc->synchronize_from_tb) {
183 cc->synchronize_from_tb(cpu, tb);
184 } else {
185 assert(cc->set_pc);
186 cc->set_pc(cpu, tb->pc);
187 }
188 }
189 if ((next_tb & TB_EXIT_MASK) == TB_EXIT_REQUESTED) {
190 /* We were asked to stop executing TBs (probably a pending
191 * interrupt. We've now stopped, so clear the flag.
192 */
193 cpu->tcg_exit_req = 0;
194 }
195 return next_tb;
196 }
197
198 /* Execute the code without caching the generated code. An interpreter
199 could be used if available. */
200 static void cpu_exec_nocache(CPUArchState *env, int max_cycles,
201 TranslationBlock *orig_tb)
202 {
203 CPUState *cpu = ENV_GET_CPU(env);
204 TranslationBlock *tb;
205
206 /* Should never happen.
207 We only end up here when an existing TB is too long. */
208 if (max_cycles > CF_COUNT_MASK)
209 max_cycles = CF_COUNT_MASK;
210
211 tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base, orig_tb->flags,
212 max_cycles);
213 cpu->current_tb = tb;
214 /* execute the generated code */
215 trace_exec_tb_nocache(tb, tb->pc);
216 cpu_tb_exec(cpu, tb->tc_ptr);
217 cpu->current_tb = NULL;
218 tb_phys_invalidate(tb, -1);
219 tb_free(tb);
220 }
221
222 static TranslationBlock *tb_find_slow(CPUArchState *env,
223 target_ulong pc,
224 target_ulong cs_base,
225 uint64_t flags)
226 {
227 CPUState *cpu = ENV_GET_CPU(env);
228 TranslationBlock *tb, **ptb1;
229 unsigned int h;
230 tb_page_addr_t phys_pc, phys_page1;
231 target_ulong virt_page2;
232
233 tcg_ctx.tb_ctx.tb_invalidated_flag = 0;
234
235 /* find translated block using physical mappings */
236 phys_pc = get_page_addr_code(env, pc);
237 phys_page1 = phys_pc & TARGET_PAGE_MASK;
238 h = tb_phys_hash_func(phys_pc);
239 ptb1 = &tcg_ctx.tb_ctx.tb_phys_hash[h];
240 for(;;) {
241 tb = *ptb1;
242 if (!tb)
243 goto not_found;
244 if (tb->pc == pc &&
245 tb->page_addr[0] == phys_page1 &&
246 tb->cs_base == cs_base &&
247 tb->flags == flags) {
248 /* check next page if needed */
249 if (tb->page_addr[1] != -1) {
250 tb_page_addr_t phys_page2;
251
252 virt_page2 = (pc & TARGET_PAGE_MASK) +
253 TARGET_PAGE_SIZE;
254 phys_page2 = get_page_addr_code(env, virt_page2);
255 if (tb->page_addr[1] == phys_page2)
256 goto found;
257 } else {
258 goto found;
259 }
260 }
261 ptb1 = &tb->phys_hash_next;
262 }
263 not_found:
264 /* if no translated code available, then translate it now */
265 tb = tb_gen_code(cpu, pc, cs_base, flags, 0);
266
267 found:
268 /* Move the last found TB to the head of the list */
269 if (likely(*ptb1)) {
270 *ptb1 = tb->phys_hash_next;
271 tb->phys_hash_next = tcg_ctx.tb_ctx.tb_phys_hash[h];
272 tcg_ctx.tb_ctx.tb_phys_hash[h] = tb;
273 }
274 /* we add the TB in the virtual pc hash table */
275 cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)] = tb;
276 return tb;
277 }
278
279 static inline TranslationBlock *tb_find_fast(CPUArchState *env)
280 {
281 CPUState *cpu = ENV_GET_CPU(env);
282 TranslationBlock *tb;
283 target_ulong cs_base, pc;
284 int flags;
285
286 /* we record a subset of the CPU state. It will
287 always be the same before a given translated block
288 is executed. */
289 cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
290 tb = cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)];
291 if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base ||
292 tb->flags != flags)) {
293 tb = tb_find_slow(env, pc, cs_base, flags);
294 }
295 return tb;
296 }
297
298 static void cpu_handle_debug_exception(CPUArchState *env)
299 {
300 CPUState *cpu = ENV_GET_CPU(env);
301 CPUClass *cc = CPU_GET_CLASS(cpu);
302 CPUWatchpoint *wp;
303
304 if (!cpu->watchpoint_hit) {
305 QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
306 wp->flags &= ~BP_WATCHPOINT_HIT;
307 }
308 }
309
310 cc->debug_excp_handler(cpu);
311 }
312
313 /* main execution loop */
314
315 volatile sig_atomic_t exit_request;
316
317 int cpu_exec(CPUArchState *env)
318 {
319 CPUState *cpu = ENV_GET_CPU(env);
320 CPUClass *cc = CPU_GET_CLASS(cpu);
321 #ifdef TARGET_I386
322 X86CPU *x86_cpu = X86_CPU(cpu);
323 #endif
324 int ret, interrupt_request;
325 TranslationBlock *tb;
326 uint8_t *tc_ptr;
327 uintptr_t next_tb;
328 SyncClocks sc;
329
330 /* This must be volatile so it is not trashed by longjmp() */
331 volatile bool have_tb_lock = false;
332
333 if (cpu->halted) {
334 if (!cpu_has_work(cpu)) {
335 return EXCP_HALTED;
336 }
337
338 cpu->halted = 0;
339 }
340
341 current_cpu = cpu;
342
343 /* As long as current_cpu is null, up to the assignment just above,
344 * requests by other threads to exit the execution loop are expected to
345 * be issued using the exit_request global. We must make sure that our
346 * evaluation of the global value is performed past the current_cpu
347 * value transition point, which requires a memory barrier as well as
348 * an instruction scheduling constraint on modern architectures. */
349 smp_mb();
350
351 if (unlikely(exit_request)) {
352 cpu->exit_request = 1;
353 }
354
355 cc->cpu_exec_enter(cpu);
356 cpu->exception_index = -1;
357
358 /* Calculate difference between guest clock and host clock.
359 * This delay includes the delay of the last cycle, so
360 * what we have to do is sleep until it is 0. As for the
361 * advance/delay we gain here, we try to fix it next time.
362 */
363 init_delay_params(&sc, cpu);
364
365 /* prepare setjmp context for exception handling */
366 for(;;) {
367 if (sigsetjmp(cpu->jmp_env, 0) == 0) {
368 /* if an exception is pending, we execute it here */
369 if (cpu->exception_index >= 0) {
370 if (cpu->exception_index >= EXCP_INTERRUPT) {
371 /* exit request from the cpu execution loop */
372 ret = cpu->exception_index;
373 if (ret == EXCP_DEBUG) {
374 cpu_handle_debug_exception(env);
375 }
376 break;
377 } else {
378 #if defined(CONFIG_USER_ONLY)
379 /* if user mode only, we simulate a fake exception
380 which will be handled outside the cpu execution
381 loop */
382 #if defined(TARGET_I386)
383 cc->do_interrupt(cpu);
384 #endif
385 ret = cpu->exception_index;
386 break;
387 #else
388 cc->do_interrupt(cpu);
389 cpu->exception_index = -1;
390 #endif
391 }
392 }
393
394 next_tb = 0; /* force lookup of first TB */
395 for(;;) {
396 interrupt_request = cpu->interrupt_request;
397 if (unlikely(interrupt_request)) {
398 if (unlikely(cpu->singlestep_enabled & SSTEP_NOIRQ)) {
399 /* Mask out external interrupts for this step. */
400 interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK;
401 }
402 if (interrupt_request & CPU_INTERRUPT_DEBUG) {
403 cpu->interrupt_request &= ~CPU_INTERRUPT_DEBUG;
404 cpu->exception_index = EXCP_DEBUG;
405 cpu_loop_exit(cpu);
406 }
407 if (interrupt_request & CPU_INTERRUPT_HALT) {
408 cpu->interrupt_request &= ~CPU_INTERRUPT_HALT;
409 cpu->halted = 1;
410 cpu->exception_index = EXCP_HLT;
411 cpu_loop_exit(cpu);
412 }
413 #if defined(TARGET_I386)
414 if (interrupt_request & CPU_INTERRUPT_INIT) {
415 cpu_svm_check_intercept_param(env, SVM_EXIT_INIT, 0);
416 do_cpu_init(x86_cpu);
417 cpu->exception_index = EXCP_HALTED;
418 cpu_loop_exit(cpu);
419 }
420 #else
421 if (interrupt_request & CPU_INTERRUPT_RESET) {
422 cpu_reset(cpu);
423 }
424 #endif
425 /* The target hook has 3 exit conditions:
426 False when the interrupt isn't processed,
427 True when it is, and we should restart on a new TB,
428 and via longjmp via cpu_loop_exit. */
429 if (cc->cpu_exec_interrupt(cpu, interrupt_request)) {
430 next_tb = 0;
431 }
432 /* Don't use the cached interrupt_request value,
433 do_interrupt may have updated the EXITTB flag. */
434 if (cpu->interrupt_request & CPU_INTERRUPT_EXITTB) {
435 cpu->interrupt_request &= ~CPU_INTERRUPT_EXITTB;
436 /* ensure that no TB jump will be modified as
437 the program flow was changed */
438 next_tb = 0;
439 }
440 }
441 if (unlikely(cpu->exit_request)) {
442 cpu->exit_request = 0;
443 cpu->exception_index = EXCP_INTERRUPT;
444 cpu_loop_exit(cpu);
445 }
446 spin_lock(&tcg_ctx.tb_ctx.tb_lock);
447 have_tb_lock = true;
448 tb = tb_find_fast(env);
449 /* Note: we do it here to avoid a gcc bug on Mac OS X when
450 doing it in tb_find_slow */
451 if (tcg_ctx.tb_ctx.tb_invalidated_flag) {
452 /* as some TB could have been invalidated because
453 of memory exceptions while generating the code, we
454 must recompute the hash index here */
455 next_tb = 0;
456 tcg_ctx.tb_ctx.tb_invalidated_flag = 0;
457 }
458 if (qemu_loglevel_mask(CPU_LOG_EXEC)) {
459 qemu_log("Trace %p [" TARGET_FMT_lx "] %s\n",
460 tb->tc_ptr, tb->pc, lookup_symbol(tb->pc));
461 }
462 /* see if we can patch the calling TB. When the TB
463 spans two pages, we cannot safely do a direct
464 jump. */
465 if (next_tb != 0 && tb->page_addr[1] == -1) {
466 tb_add_jump((TranslationBlock *)(next_tb & ~TB_EXIT_MASK),
467 next_tb & TB_EXIT_MASK, tb);
468 }
469 have_tb_lock = false;
470 spin_unlock(&tcg_ctx.tb_ctx.tb_lock);
471
472 /* cpu_interrupt might be called while translating the
473 TB, but before it is linked into a potentially
474 infinite loop and becomes env->current_tb. Avoid
475 starting execution if there is a pending interrupt. */
476 cpu->current_tb = tb;
477 barrier();
478 if (likely(!cpu->exit_request)) {
479 trace_exec_tb(tb, tb->pc);
480 tc_ptr = tb->tc_ptr;
481 /* execute the generated code */
482 next_tb = cpu_tb_exec(cpu, tc_ptr);
483 switch (next_tb & TB_EXIT_MASK) {
484 case TB_EXIT_REQUESTED:
485 /* Something asked us to stop executing
486 * chained TBs; just continue round the main
487 * loop. Whatever requested the exit will also
488 * have set something else (eg exit_request or
489 * interrupt_request) which we will handle
490 * next time around the loop.
491 */
492 tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
493 next_tb = 0;
494 break;
495 case TB_EXIT_ICOUNT_EXPIRED:
496 {
497 /* Instruction counter expired. */
498 int insns_left;
499 tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
500 insns_left = cpu->icount_decr.u32;
501 if (cpu->icount_extra && insns_left >= 0) {
502 /* Refill decrementer and continue execution. */
503 cpu->icount_extra += insns_left;
504 if (cpu->icount_extra > 0xffff) {
505 insns_left = 0xffff;
506 } else {
507 insns_left = cpu->icount_extra;
508 }
509 cpu->icount_extra -= insns_left;
510 cpu->icount_decr.u16.low = insns_left;
511 } else {
512 if (insns_left > 0) {
513 /* Execute remaining instructions. */
514 cpu_exec_nocache(env, insns_left, tb);
515 align_clocks(&sc, cpu);
516 }
517 cpu->exception_index = EXCP_INTERRUPT;
518 next_tb = 0;
519 cpu_loop_exit(cpu);
520 }
521 break;
522 }
523 default:
524 break;
525 }
526 }
527 cpu->current_tb = NULL;
528 /* Try to align the host and virtual clocks
529 if the guest is in advance */
530 align_clocks(&sc, cpu);
531 /* reset soft MMU for next block (it can currently
532 only be set by a memory fault) */
533 } /* for(;;) */
534 } else {
535 /* Reload env after longjmp - the compiler may have smashed all
536 * local variables as longjmp is marked 'noreturn'. */
537 cpu = current_cpu;
538 env = cpu->env_ptr;
539 cc = CPU_GET_CLASS(cpu);
540 #ifdef TARGET_I386
541 x86_cpu = X86_CPU(cpu);
542 #endif
543 if (have_tb_lock) {
544 spin_unlock(&tcg_ctx.tb_ctx.tb_lock);
545 have_tb_lock = false;
546 }
547 }
548 } /* for(;;) */
549
550 cc->cpu_exec_exit(cpu);
551
552 /* fail safe : never use current_cpu outside cpu_exec() */
553 current_cpu = NULL;
554 return ret;
555 }