2 * emulator main execution loop
4 * Copyright (c) 2003-2005 Fabrice Bellard
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.
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.
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/>.
22 #include "disas/disas.h"
24 #include "qemu/atomic.h"
25 #include "sysemu/qtest.h"
26 #include "qemu/timer.h"
28 /* -icount align implementation. */
30 typedef struct SyncClocks
{
32 int64_t last_cpu_icount
;
33 int64_t realtime_clock
;
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
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
46 static void align_clocks(SyncClocks
*sc
, const CPUState
*cpu
)
50 if (!icount_align_option
) {
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
;
58 if (sc
->diff_clk
> VM_CLOCK_ADVANCE
) {
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
= rem_delay
.tv_sec
* 1000000000LL + rem_delay
.tv_nsec
;
69 Sleep(sc
->diff_clk
/ SCALE_MS
);
75 static void print_delay(const SyncClocks
*sc
)
77 static float threshold_delay
;
78 static int64_t last_realtime_clock
;
81 if (icount_align_option
&&
82 sc
->realtime_clock
- last_realtime_clock
>= MAX_DELAY_PRINT_RATE
&&
83 nb_prints
< MAX_NB_PRINTS
) {
84 if ((-sc
->diff_clk
/ (float)1000000000LL > threshold_delay
) ||
85 (-sc
->diff_clk
/ (float)1000000000LL <
86 (threshold_delay
- THRESHOLD_REDUCE
))) {
87 threshold_delay
= (-sc
->diff_clk
/ 1000000000LL) + 1;
88 printf("Warning: The guest is now late by %.1f to %.1f seconds\n",
92 last_realtime_clock
= sc
->realtime_clock
;
97 static void init_delay_params(SyncClocks
*sc
,
100 if (!icount_align_option
) {
103 sc
->realtime_clock
= qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT
);
104 sc
->diff_clk
= qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL
) - sc
->realtime_clock
;
105 sc
->last_cpu_icount
= cpu
->icount_extra
+ cpu
->icount_decr
.u16
.low
;
106 if (sc
->diff_clk
< max_delay
) {
107 max_delay
= sc
->diff_clk
;
109 if (sc
->diff_clk
> max_advance
) {
110 max_advance
= sc
->diff_clk
;
113 /* Print every 2s max if the guest is late. We limit the number
114 of printed messages to NB_PRINT_MAX(currently 100) */
118 static void align_clocks(SyncClocks
*sc
, const CPUState
*cpu
)
122 static void init_delay_params(SyncClocks
*sc
, const CPUState
*cpu
)
125 #endif /* CONFIG USER ONLY */
127 void cpu_loop_exit(CPUState
*cpu
)
129 cpu
->current_tb
= NULL
;
130 siglongjmp(cpu
->jmp_env
, 1);
133 /* exit the current TB from a signal handler. The host registers are
134 restored in a state compatible with the CPU emulator
136 #if defined(CONFIG_SOFTMMU)
137 void cpu_resume_from_signal(CPUState
*cpu
, void *puc
)
139 /* XXX: restore cpu registers saved in host registers */
141 cpu
->exception_index
= -1;
142 siglongjmp(cpu
->jmp_env
, 1);
145 void cpu_reload_memory_map(CPUState
*cpu
)
147 /* The TLB is protected by the iothread lock. */
152 /* Execute a TB, and fix up the CPU state afterwards if necessary */
153 static inline tcg_target_ulong
cpu_tb_exec(CPUState
*cpu
, uint8_t *tb_ptr
)
155 CPUArchState
*env
= cpu
->env_ptr
;
158 #if defined(DEBUG_DISAS)
159 if (qemu_loglevel_mask(CPU_LOG_TB_CPU
)) {
160 #if defined(TARGET_I386)
161 log_cpu_state(cpu
, CPU_DUMP_CCOP
);
162 #elif defined(TARGET_M68K)
163 /* ??? Should not modify env state for dumping. */
164 cpu_m68k_flush_flags(env
, env
->cc_op
);
165 env
->cc_op
= CC_OP_FLAGS
;
166 env
->sr
= (env
->sr
& 0xffe0) | env
->cc_dest
| (env
->cc_x
<< 4);
167 log_cpu_state(cpu
, 0);
169 log_cpu_state(cpu
, 0);
172 #endif /* DEBUG_DISAS */
175 next_tb
= tcg_qemu_tb_exec(env
, tb_ptr
);
177 trace_exec_tb_exit((void *) (next_tb
& ~TB_EXIT_MASK
),
178 next_tb
& TB_EXIT_MASK
);
180 if ((next_tb
& TB_EXIT_MASK
) > TB_EXIT_IDX1
) {
181 /* We didn't start executing this TB (eg because the instruction
182 * counter hit zero); we must restore the guest PC to the address
183 * of the start of the TB.
185 CPUClass
*cc
= CPU_GET_CLASS(cpu
);
186 TranslationBlock
*tb
= (TranslationBlock
*)(next_tb
& ~TB_EXIT_MASK
);
187 if (cc
->synchronize_from_tb
) {
188 cc
->synchronize_from_tb(cpu
, tb
);
191 cc
->set_pc(cpu
, tb
->pc
);
194 if ((next_tb
& TB_EXIT_MASK
) == TB_EXIT_REQUESTED
) {
195 /* We were asked to stop executing TBs (probably a pending
196 * interrupt. We've now stopped, so clear the flag.
198 cpu
->tcg_exit_req
= 0;
203 /* Execute the code without caching the generated code. An interpreter
204 could be used if available. */
205 static void cpu_exec_nocache(CPUArchState
*env
, int max_cycles
,
206 TranslationBlock
*orig_tb
)
208 CPUState
*cpu
= ENV_GET_CPU(env
);
209 TranslationBlock
*tb
;
210 target_ulong pc
= orig_tb
->pc
;
211 target_ulong cs_base
= orig_tb
->cs_base
;
212 uint64_t flags
= orig_tb
->flags
;
214 /* Should never happen.
215 We only end up here when an existing TB is too long. */
216 if (max_cycles
> CF_COUNT_MASK
)
217 max_cycles
= CF_COUNT_MASK
;
219 /* tb_gen_code can flush our orig_tb, invalidate it now */
220 tb_phys_invalidate(orig_tb
, -1);
221 tb
= tb_gen_code(cpu
, pc
, cs_base
, flags
,
222 max_cycles
| CF_NOCACHE
);
223 cpu
->current_tb
= tb
;
224 /* execute the generated code */
225 trace_exec_tb_nocache(tb
, tb
->pc
);
226 cpu_tb_exec(cpu
, tb
->tc_ptr
);
227 cpu
->current_tb
= NULL
;
228 tb_phys_invalidate(tb
, -1);
232 static TranslationBlock
*tb_find_slow(CPUArchState
*env
,
234 target_ulong cs_base
,
237 CPUState
*cpu
= ENV_GET_CPU(env
);
238 TranslationBlock
*tb
, **ptb1
;
240 tb_page_addr_t phys_pc
, phys_page1
;
241 target_ulong virt_page2
;
243 tcg_ctx
.tb_ctx
.tb_invalidated_flag
= 0;
245 /* find translated block using physical mappings */
246 phys_pc
= get_page_addr_code(env
, pc
);
247 phys_page1
= phys_pc
& TARGET_PAGE_MASK
;
248 h
= tb_phys_hash_func(phys_pc
);
249 ptb1
= &tcg_ctx
.tb_ctx
.tb_phys_hash
[h
];
255 tb
->page_addr
[0] == phys_page1
&&
256 tb
->cs_base
== cs_base
&&
257 tb
->flags
== flags
) {
258 /* check next page if needed */
259 if (tb
->page_addr
[1] != -1) {
260 tb_page_addr_t phys_page2
;
262 virt_page2
= (pc
& TARGET_PAGE_MASK
) +
264 phys_page2
= get_page_addr_code(env
, virt_page2
);
265 if (tb
->page_addr
[1] == phys_page2
)
271 ptb1
= &tb
->phys_hash_next
;
274 /* if no translated code available, then translate it now */
275 tb
= tb_gen_code(cpu
, pc
, cs_base
, flags
, 0);
278 /* Move the last found TB to the head of the list */
280 *ptb1
= tb
->phys_hash_next
;
281 tb
->phys_hash_next
= tcg_ctx
.tb_ctx
.tb_phys_hash
[h
];
282 tcg_ctx
.tb_ctx
.tb_phys_hash
[h
] = tb
;
284 /* we add the TB in the virtual pc hash table */
285 cpu
->tb_jmp_cache
[tb_jmp_cache_hash_func(pc
)] = tb
;
289 static inline TranslationBlock
*tb_find_fast(CPUArchState
*env
)
291 CPUState
*cpu
= ENV_GET_CPU(env
);
292 TranslationBlock
*tb
;
293 target_ulong cs_base
, pc
;
296 /* we record a subset of the CPU state. It will
297 always be the same before a given translated block
299 cpu_get_tb_cpu_state(env
, &pc
, &cs_base
, &flags
);
300 tb
= cpu
->tb_jmp_cache
[tb_jmp_cache_hash_func(pc
)];
301 if (unlikely(!tb
|| tb
->pc
!= pc
|| tb
->cs_base
!= cs_base
||
302 tb
->flags
!= flags
)) {
303 tb
= tb_find_slow(env
, pc
, cs_base
, flags
);
308 static void cpu_handle_debug_exception(CPUArchState
*env
)
310 CPUState
*cpu
= ENV_GET_CPU(env
);
311 CPUClass
*cc
= CPU_GET_CLASS(cpu
);
314 if (!cpu
->watchpoint_hit
) {
315 QTAILQ_FOREACH(wp
, &cpu
->watchpoints
, entry
) {
316 wp
->flags
&= ~BP_WATCHPOINT_HIT
;
320 cc
->debug_excp_handler(cpu
);
323 /* main execution loop */
325 volatile sig_atomic_t exit_request
;
327 int cpu_exec(CPUArchState
*env
)
329 CPUState
*cpu
= ENV_GET_CPU(env
);
330 CPUClass
*cc
= CPU_GET_CLASS(cpu
);
332 X86CPU
*x86_cpu
= X86_CPU(cpu
);
334 int ret
, interrupt_request
;
335 TranslationBlock
*tb
;
340 /* This must be volatile so it is not trashed by longjmp() */
341 volatile bool have_tb_lock
= false;
344 if (!cpu_has_work(cpu
)) {
353 /* As long as current_cpu is null, up to the assignment just above,
354 * requests by other threads to exit the execution loop are expected to
355 * be issued using the exit_request global. We must make sure that our
356 * evaluation of the global value is performed past the current_cpu
357 * value transition point, which requires a memory barrier as well as
358 * an instruction scheduling constraint on modern architectures. */
361 if (unlikely(exit_request
)) {
362 cpu
->exit_request
= 1;
365 cc
->cpu_exec_enter(cpu
);
367 /* Calculate difference between guest clock and host clock.
368 * This delay includes the delay of the last cycle, so
369 * what we have to do is sleep until it is 0. As for the
370 * advance/delay we gain here, we try to fix it next time.
372 init_delay_params(&sc
, cpu
);
374 /* prepare setjmp context for exception handling */
376 if (sigsetjmp(cpu
->jmp_env
, 0) == 0) {
377 /* if an exception is pending, we execute it here */
378 if (cpu
->exception_index
>= 0) {
379 if (cpu
->exception_index
>= EXCP_INTERRUPT
) {
380 /* exit request from the cpu execution loop */
381 ret
= cpu
->exception_index
;
382 if (ret
== EXCP_DEBUG
) {
383 cpu_handle_debug_exception(env
);
385 cpu
->exception_index
= -1;
388 #if defined(CONFIG_USER_ONLY)
389 /* if user mode only, we simulate a fake exception
390 which will be handled outside the cpu execution
392 #if defined(TARGET_I386)
393 cc
->do_interrupt(cpu
);
395 ret
= cpu
->exception_index
;
396 cpu
->exception_index
= -1;
399 cc
->do_interrupt(cpu
);
400 cpu
->exception_index
= -1;
405 next_tb
= 0; /* force lookup of first TB */
407 interrupt_request
= cpu
->interrupt_request
;
408 if (unlikely(interrupt_request
)) {
409 if (unlikely(cpu
->singlestep_enabled
& SSTEP_NOIRQ
)) {
410 /* Mask out external interrupts for this step. */
411 interrupt_request
&= ~CPU_INTERRUPT_SSTEP_MASK
;
413 if (interrupt_request
& CPU_INTERRUPT_DEBUG
) {
414 cpu
->interrupt_request
&= ~CPU_INTERRUPT_DEBUG
;
415 cpu
->exception_index
= EXCP_DEBUG
;
418 if (interrupt_request
& CPU_INTERRUPT_HALT
) {
419 cpu
->interrupt_request
&= ~CPU_INTERRUPT_HALT
;
421 cpu
->exception_index
= EXCP_HLT
;
424 #if defined(TARGET_I386)
425 if (interrupt_request
& CPU_INTERRUPT_INIT
) {
426 cpu_svm_check_intercept_param(env
, SVM_EXIT_INIT
, 0);
427 do_cpu_init(x86_cpu
);
428 cpu
->exception_index
= EXCP_HALTED
;
432 if (interrupt_request
& CPU_INTERRUPT_RESET
) {
436 /* The target hook has 3 exit conditions:
437 False when the interrupt isn't processed,
438 True when it is, and we should restart on a new TB,
439 and via longjmp via cpu_loop_exit. */
440 if (cc
->cpu_exec_interrupt(cpu
, interrupt_request
)) {
443 /* Don't use the cached interrupt_request value,
444 do_interrupt may have updated the EXITTB flag. */
445 if (cpu
->interrupt_request
& CPU_INTERRUPT_EXITTB
) {
446 cpu
->interrupt_request
&= ~CPU_INTERRUPT_EXITTB
;
447 /* ensure that no TB jump will be modified as
448 the program flow was changed */
452 if (unlikely(cpu
->exit_request
)) {
453 cpu
->exit_request
= 0;
454 cpu
->exception_index
= EXCP_INTERRUPT
;
457 spin_lock(&tcg_ctx
.tb_ctx
.tb_lock
);
459 tb
= tb_find_fast(env
);
460 /* Note: we do it here to avoid a gcc bug on Mac OS X when
461 doing it in tb_find_slow */
462 if (tcg_ctx
.tb_ctx
.tb_invalidated_flag
) {
463 /* as some TB could have been invalidated because
464 of memory exceptions while generating the code, we
465 must recompute the hash index here */
467 tcg_ctx
.tb_ctx
.tb_invalidated_flag
= 0;
469 if (qemu_loglevel_mask(CPU_LOG_EXEC
)) {
470 qemu_log("Trace %p [" TARGET_FMT_lx
"] %s\n",
471 tb
->tc_ptr
, tb
->pc
, lookup_symbol(tb
->pc
));
473 /* see if we can patch the calling TB. When the TB
474 spans two pages, we cannot safely do a direct
476 if (next_tb
!= 0 && tb
->page_addr
[1] == -1) {
477 tb_add_jump((TranslationBlock
*)(next_tb
& ~TB_EXIT_MASK
),
478 next_tb
& TB_EXIT_MASK
, tb
);
480 have_tb_lock
= false;
481 spin_unlock(&tcg_ctx
.tb_ctx
.tb_lock
);
483 /* cpu_interrupt might be called while translating the
484 TB, but before it is linked into a potentially
485 infinite loop and becomes env->current_tb. Avoid
486 starting execution if there is a pending interrupt. */
487 cpu
->current_tb
= tb
;
489 if (likely(!cpu
->exit_request
)) {
490 trace_exec_tb(tb
, tb
->pc
);
492 /* execute the generated code */
493 next_tb
= cpu_tb_exec(cpu
, tc_ptr
);
494 switch (next_tb
& TB_EXIT_MASK
) {
495 case TB_EXIT_REQUESTED
:
496 /* Something asked us to stop executing
497 * chained TBs; just continue round the main
498 * loop. Whatever requested the exit will also
499 * have set something else (eg exit_request or
500 * interrupt_request) which we will handle
501 * next time around the loop.
503 tb
= (TranslationBlock
*)(next_tb
& ~TB_EXIT_MASK
);
506 case TB_EXIT_ICOUNT_EXPIRED
:
508 /* Instruction counter expired. */
510 tb
= (TranslationBlock
*)(next_tb
& ~TB_EXIT_MASK
);
511 insns_left
= cpu
->icount_decr
.u32
;
512 if (cpu
->icount_extra
&& insns_left
>= 0) {
513 /* Refill decrementer and continue execution. */
514 cpu
->icount_extra
+= insns_left
;
515 if (cpu
->icount_extra
> 0xffff) {
518 insns_left
= cpu
->icount_extra
;
520 cpu
->icount_extra
-= insns_left
;
521 cpu
->icount_decr
.u16
.low
= insns_left
;
523 if (insns_left
> 0) {
524 /* Execute remaining instructions. */
525 cpu_exec_nocache(env
, insns_left
, tb
);
526 align_clocks(&sc
, cpu
);
528 cpu
->exception_index
= EXCP_INTERRUPT
;
538 cpu
->current_tb
= NULL
;
539 /* Try to align the host and virtual clocks
540 if the guest is in advance */
541 align_clocks(&sc
, cpu
);
542 /* reset soft MMU for next block (it can currently
543 only be set by a memory fault) */
546 /* Reload env after longjmp - the compiler may have smashed all
547 * local variables as longjmp is marked 'noreturn'. */
550 cc
= CPU_GET_CLASS(cpu
);
553 x86_cpu
= X86_CPU(cpu
);
556 spin_unlock(&tcg_ctx
.tb_ctx
.tb_lock
);
557 have_tb_lock
= false;
562 cc
->cpu_exec_exit(cpu
);
564 /* fail safe : never use current_cpu outside cpu_exec() */