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267f685b PB |
1 | /* |
2 | * CPU thread main loop - common bits for user and system mode emulation | |
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 | |
d6ea4236 | 9 | * version 2.1 of the License, or (at your option) any later version. |
267f685b PB |
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" | |
53f5ed95 | 21 | #include "qemu/main-loop.h" |
267f685b | 22 | #include "exec/cpu-common.h" |
2e5b09fd | 23 | #include "hw/core/cpu.h" |
267f685b | 24 | #include "sysemu/cpus.h" |
6e8a355d | 25 | #include "qemu/lockable.h" |
8a8dc267 | 26 | #include "trace/trace-root.h" |
267f685b | 27 | |
370ed600 | 28 | QemuMutex qemu_cpu_list_lock; |
ab129972 PB |
29 | static QemuCond exclusive_cond; |
30 | static QemuCond exclusive_resume; | |
d148d90e | 31 | static QemuCond qemu_work_cond; |
267f685b | 32 | |
c265e976 PB |
33 | /* >= 1 if a thread is inside start_exclusive/end_exclusive. Written |
34 | * under qemu_cpu_list_lock, read with atomic operations. | |
35 | */ | |
ab129972 PB |
36 | static int pending_cpus; |
37 | ||
267f685b PB |
38 | void qemu_init_cpu_list(void) |
39 | { | |
ab129972 PB |
40 | /* This is needed because qemu_init_cpu_list is also called by the |
41 | * child process in a fork. */ | |
42 | pending_cpus = 0; | |
43 | ||
267f685b | 44 | qemu_mutex_init(&qemu_cpu_list_lock); |
ab129972 PB |
45 | qemu_cond_init(&exclusive_cond); |
46 | qemu_cond_init(&exclusive_resume); | |
d148d90e | 47 | qemu_cond_init(&qemu_work_cond); |
267f685b PB |
48 | } |
49 | ||
50 | void cpu_list_lock(void) | |
51 | { | |
52 | qemu_mutex_lock(&qemu_cpu_list_lock); | |
53 | } | |
54 | ||
55 | void cpu_list_unlock(void) | |
56 | { | |
57 | qemu_mutex_unlock(&qemu_cpu_list_lock); | |
58 | } | |
59 | ||
60 | static bool cpu_index_auto_assigned; | |
61 | ||
62 | static int cpu_get_free_index(void) | |
63 | { | |
64 | CPUState *some_cpu; | |
716386e3 | 65 | int max_cpu_index = 0; |
267f685b PB |
66 | |
67 | cpu_index_auto_assigned = true; | |
68 | CPU_FOREACH(some_cpu) { | |
716386e3 AB |
69 | if (some_cpu->cpu_index >= max_cpu_index) { |
70 | max_cpu_index = some_cpu->cpu_index + 1; | |
71 | } | |
267f685b | 72 | } |
716386e3 | 73 | return max_cpu_index; |
267f685b PB |
74 | } |
75 | ||
421a75e2 | 76 | CPUTailQ cpus = QTAILQ_HEAD_INITIALIZER(cpus); |
ab1a161f HH |
77 | static unsigned int cpu_list_generation_id; |
78 | ||
79 | unsigned int cpu_list_generation_id_get(void) | |
80 | { | |
81 | return cpu_list_generation_id; | |
82 | } | |
421a75e2 | 83 | |
267f685b PB |
84 | void cpu_list_add(CPUState *cpu) |
85 | { | |
6e8a355d | 86 | QEMU_LOCK_GUARD(&qemu_cpu_list_lock); |
267f685b PB |
87 | if (cpu->cpu_index == UNASSIGNED_CPU_INDEX) { |
88 | cpu->cpu_index = cpu_get_free_index(); | |
89 | assert(cpu->cpu_index != UNASSIGNED_CPU_INDEX); | |
90 | } else { | |
91 | assert(!cpu_index_auto_assigned); | |
92 | } | |
068a5ea0 | 93 | QTAILQ_INSERT_TAIL_RCU(&cpus, cpu, node); |
ab1a161f | 94 | cpu_list_generation_id++; |
267f685b PB |
95 | } |
96 | ||
97 | void cpu_list_remove(CPUState *cpu) | |
98 | { | |
6e8a355d | 99 | QEMU_LOCK_GUARD(&qemu_cpu_list_lock); |
267f685b PB |
100 | if (!QTAILQ_IN_USE(cpu, node)) { |
101 | /* there is nothing to undo since cpu_exec_init() hasn't been called */ | |
267f685b PB |
102 | return; |
103 | } | |
104 | ||
068a5ea0 | 105 | QTAILQ_REMOVE_RCU(&cpus, cpu, node); |
267f685b | 106 | cpu->cpu_index = UNASSIGNED_CPU_INDEX; |
ab1a161f | 107 | cpu_list_generation_id++; |
267f685b | 108 | } |
d148d90e | 109 | |
421a75e2 PMD |
110 | CPUState *qemu_get_cpu(int index) |
111 | { | |
112 | CPUState *cpu; | |
113 | ||
114 | CPU_FOREACH(cpu) { | |
115 | if (cpu->cpu_index == index) { | |
116 | return cpu; | |
117 | } | |
118 | } | |
119 | ||
120 | return NULL; | |
121 | } | |
122 | ||
123 | /* current CPU in the current thread. It is only valid inside cpu_exec() */ | |
124 | __thread CPUState *current_cpu; | |
125 | ||
d148d90e | 126 | struct qemu_work_item { |
0c0fcc20 | 127 | QSIMPLEQ_ENTRY(qemu_work_item) node; |
d148d90e | 128 | run_on_cpu_func func; |
14e6fe12 | 129 | run_on_cpu_data data; |
53f5ed95 | 130 | bool free, exclusive, done; |
d148d90e SF |
131 | }; |
132 | ||
133 | static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi) | |
134 | { | |
135 | qemu_mutex_lock(&cpu->work_mutex); | |
0c0fcc20 | 136 | QSIMPLEQ_INSERT_TAIL(&cpu->work_list, wi, node); |
d148d90e SF |
137 | wi->done = false; |
138 | qemu_mutex_unlock(&cpu->work_mutex); | |
139 | ||
140 | qemu_cpu_kick(cpu); | |
141 | } | |
142 | ||
14e6fe12 | 143 | void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data, |
d148d90e SF |
144 | QemuMutex *mutex) |
145 | { | |
146 | struct qemu_work_item wi; | |
147 | ||
148 | if (qemu_cpu_is_self(cpu)) { | |
149 | func(cpu, data); | |
150 | return; | |
151 | } | |
152 | ||
153 | wi.func = func; | |
154 | wi.data = data; | |
0e55539c | 155 | wi.done = false; |
d148d90e | 156 | wi.free = false; |
53f5ed95 | 157 | wi.exclusive = false; |
d148d90e SF |
158 | |
159 | queue_work_on_cpu(cpu, &wi); | |
42abcc58 | 160 | while (!qatomic_load_acquire(&wi.done)) { |
d148d90e SF |
161 | CPUState *self_cpu = current_cpu; |
162 | ||
163 | qemu_cond_wait(&qemu_work_cond, mutex); | |
164 | current_cpu = self_cpu; | |
165 | } | |
166 | } | |
167 | ||
14e6fe12 | 168 | void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data) |
d148d90e SF |
169 | { |
170 | struct qemu_work_item *wi; | |
171 | ||
b21e2380 | 172 | wi = g_new0(struct qemu_work_item, 1); |
d148d90e SF |
173 | wi->func = func; |
174 | wi->data = data; | |
175 | wi->free = true; | |
176 | ||
177 | queue_work_on_cpu(cpu, wi); | |
178 | } | |
179 | ||
ab129972 PB |
180 | /* Wait for pending exclusive operations to complete. The CPU list lock |
181 | must be held. */ | |
182 | static inline void exclusive_idle(void) | |
183 | { | |
184 | while (pending_cpus) { | |
185 | qemu_cond_wait(&exclusive_resume, &qemu_cpu_list_lock); | |
186 | } | |
187 | } | |
188 | ||
189 | /* Start an exclusive operation. | |
758e1b2b | 190 | Must only be called from outside cpu_exec. */ |
ab129972 PB |
191 | void start_exclusive(void) |
192 | { | |
193 | CPUState *other_cpu; | |
c265e976 | 194 | int running_cpus; |
ab129972 | 195 | |
df8a6880 IL |
196 | if (current_cpu->exclusive_context_count) { |
197 | current_cpu->exclusive_context_count++; | |
198 | return; | |
199 | } | |
200 | ||
ab129972 PB |
201 | qemu_mutex_lock(&qemu_cpu_list_lock); |
202 | exclusive_idle(); | |
203 | ||
204 | /* Make all other cpus stop executing. */ | |
d73415a3 | 205 | qatomic_set(&pending_cpus, 1); |
c265e976 PB |
206 | |
207 | /* Write pending_cpus before reading other_cpu->running. */ | |
208 | smp_mb(); | |
209 | running_cpus = 0; | |
ab129972 | 210 | CPU_FOREACH(other_cpu) { |
d73415a3 | 211 | if (qatomic_read(&other_cpu->running)) { |
c265e976 PB |
212 | other_cpu->has_waiter = true; |
213 | running_cpus++; | |
ab129972 PB |
214 | qemu_cpu_kick(other_cpu); |
215 | } | |
216 | } | |
c265e976 | 217 | |
d73415a3 | 218 | qatomic_set(&pending_cpus, running_cpus + 1); |
ab129972 PB |
219 | while (pending_cpus > 1) { |
220 | qemu_cond_wait(&exclusive_cond, &qemu_cpu_list_lock); | |
221 | } | |
758e1b2b PB |
222 | |
223 | /* Can release mutex, no one will enter another exclusive | |
224 | * section until end_exclusive resets pending_cpus to 0. | |
225 | */ | |
226 | qemu_mutex_unlock(&qemu_cpu_list_lock); | |
cfbc3c60 | 227 | |
df8a6880 | 228 | current_cpu->exclusive_context_count = 1; |
ab129972 PB |
229 | } |
230 | ||
758e1b2b | 231 | /* Finish an exclusive operation. */ |
ab129972 PB |
232 | void end_exclusive(void) |
233 | { | |
df8a6880 IL |
234 | current_cpu->exclusive_context_count--; |
235 | if (current_cpu->exclusive_context_count) { | |
236 | return; | |
237 | } | |
cfbc3c60 | 238 | |
758e1b2b | 239 | qemu_mutex_lock(&qemu_cpu_list_lock); |
d73415a3 | 240 | qatomic_set(&pending_cpus, 0); |
ab129972 PB |
241 | qemu_cond_broadcast(&exclusive_resume); |
242 | qemu_mutex_unlock(&qemu_cpu_list_lock); | |
243 | } | |
244 | ||
245 | /* Wait for exclusive ops to finish, and begin cpu execution. */ | |
246 | void cpu_exec_start(CPUState *cpu) | |
247 | { | |
d73415a3 | 248 | qatomic_set(&cpu->running, true); |
c265e976 PB |
249 | |
250 | /* Write cpu->running before reading pending_cpus. */ | |
251 | smp_mb(); | |
252 | ||
253 | /* 1. start_exclusive saw cpu->running == true and pending_cpus >= 1. | |
254 | * After taking the lock we'll see cpu->has_waiter == true and run---not | |
255 | * for long because start_exclusive kicked us. cpu_exec_end will | |
256 | * decrement pending_cpus and signal the waiter. | |
257 | * | |
258 | * 2. start_exclusive saw cpu->running == false but pending_cpus >= 1. | |
259 | * This includes the case when an exclusive item is running now. | |
260 | * Then we'll see cpu->has_waiter == false and wait for the item to | |
261 | * complete. | |
262 | * | |
263 | * 3. pending_cpus == 0. Then start_exclusive is definitely going to | |
264 | * see cpu->running == true, and it will kick the CPU. | |
265 | */ | |
d73415a3 | 266 | if (unlikely(qatomic_read(&pending_cpus))) { |
6e8a355d | 267 | QEMU_LOCK_GUARD(&qemu_cpu_list_lock); |
c265e976 PB |
268 | if (!cpu->has_waiter) { |
269 | /* Not counted in pending_cpus, let the exclusive item | |
270 | * run. Since we have the lock, just set cpu->running to true | |
271 | * while holding it; no need to check pending_cpus again. | |
272 | */ | |
d73415a3 | 273 | qatomic_set(&cpu->running, false); |
c265e976 PB |
274 | exclusive_idle(); |
275 | /* Now pending_cpus is zero. */ | |
d73415a3 | 276 | qatomic_set(&cpu->running, true); |
c265e976 PB |
277 | } else { |
278 | /* Counted in pending_cpus, go ahead and release the | |
279 | * waiter at cpu_exec_end. | |
280 | */ | |
281 | } | |
c265e976 | 282 | } |
ab129972 PB |
283 | } |
284 | ||
285 | /* Mark cpu as not executing, and release pending exclusive ops. */ | |
286 | void cpu_exec_end(CPUState *cpu) | |
287 | { | |
d73415a3 | 288 | qatomic_set(&cpu->running, false); |
c265e976 PB |
289 | |
290 | /* Write cpu->running before reading pending_cpus. */ | |
291 | smp_mb(); | |
292 | ||
293 | /* 1. start_exclusive saw cpu->running == true. Then it will increment | |
294 | * pending_cpus and wait for exclusive_cond. After taking the lock | |
295 | * we'll see cpu->has_waiter == true. | |
296 | * | |
297 | * 2. start_exclusive saw cpu->running == false but here pending_cpus >= 1. | |
298 | * This includes the case when an exclusive item started after setting | |
299 | * cpu->running to false and before we read pending_cpus. Then we'll see | |
300 | * cpu->has_waiter == false and not touch pending_cpus. The next call to | |
301 | * cpu_exec_start will run exclusive_idle if still necessary, thus waiting | |
302 | * for the item to complete. | |
303 | * | |
304 | * 3. pending_cpus == 0. Then start_exclusive is definitely going to | |
305 | * see cpu->running == false, and it can ignore this CPU until the | |
306 | * next cpu_exec_start. | |
307 | */ | |
d73415a3 | 308 | if (unlikely(qatomic_read(&pending_cpus))) { |
6e8a355d | 309 | QEMU_LOCK_GUARD(&qemu_cpu_list_lock); |
c265e976 PB |
310 | if (cpu->has_waiter) { |
311 | cpu->has_waiter = false; | |
d73415a3 | 312 | qatomic_set(&pending_cpus, pending_cpus - 1); |
c265e976 PB |
313 | if (pending_cpus == 1) { |
314 | qemu_cond_signal(&exclusive_cond); | |
315 | } | |
ab129972 PB |
316 | } |
317 | } | |
ab129972 PB |
318 | } |
319 | ||
14e6fe12 PB |
320 | void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, |
321 | run_on_cpu_data data) | |
53f5ed95 PB |
322 | { |
323 | struct qemu_work_item *wi; | |
324 | ||
b21e2380 | 325 | wi = g_new0(struct qemu_work_item, 1); |
53f5ed95 PB |
326 | wi->func = func; |
327 | wi->data = data; | |
328 | wi->free = true; | |
329 | wi->exclusive = true; | |
330 | ||
331 | queue_work_on_cpu(cpu, wi); | |
332 | } | |
333 | ||
d148d90e SF |
334 | void process_queued_cpu_work(CPUState *cpu) |
335 | { | |
336 | struct qemu_work_item *wi; | |
337 | ||
0c0fcc20 EC |
338 | qemu_mutex_lock(&cpu->work_mutex); |
339 | if (QSIMPLEQ_EMPTY(&cpu->work_list)) { | |
340 | qemu_mutex_unlock(&cpu->work_mutex); | |
d148d90e SF |
341 | return; |
342 | } | |
0c0fcc20 EC |
343 | while (!QSIMPLEQ_EMPTY(&cpu->work_list)) { |
344 | wi = QSIMPLEQ_FIRST(&cpu->work_list); | |
345 | QSIMPLEQ_REMOVE_HEAD(&cpu->work_list, node); | |
d148d90e | 346 | qemu_mutex_unlock(&cpu->work_mutex); |
53f5ed95 PB |
347 | if (wi->exclusive) { |
348 | /* Running work items outside the BQL avoids the following deadlock: | |
349 | * 1) start_exclusive() is called with the BQL taken while another | |
350 | * CPU is running; 2) cpu_exec in the other CPU tries to takes the | |
351 | * BQL, so it goes to sleep; start_exclusive() is sleeping too, so | |
352 | * neither CPU can proceed. | |
353 | */ | |
354 | qemu_mutex_unlock_iothread(); | |
355 | start_exclusive(); | |
356 | wi->func(cpu, wi->data); | |
357 | end_exclusive(); | |
358 | qemu_mutex_lock_iothread(); | |
359 | } else { | |
360 | wi->func(cpu, wi->data); | |
361 | } | |
d148d90e SF |
362 | qemu_mutex_lock(&cpu->work_mutex); |
363 | if (wi->free) { | |
364 | g_free(wi); | |
365 | } else { | |
42abcc58 | 366 | qatomic_store_release(&wi->done, true); |
d148d90e SF |
367 | } |
368 | } | |
369 | qemu_mutex_unlock(&cpu->work_mutex); | |
370 | qemu_cond_broadcast(&qemu_work_cond); | |
371 | } | |
8a8dc267 PMD |
372 | |
373 | /* Add a breakpoint. */ | |
374 | int cpu_breakpoint_insert(CPUState *cpu, vaddr pc, int flags, | |
375 | CPUBreakpoint **breakpoint) | |
376 | { | |
377 | CPUClass *cc = CPU_GET_CLASS(cpu); | |
378 | CPUBreakpoint *bp; | |
379 | ||
380 | if (cc->gdb_adjust_breakpoint) { | |
381 | pc = cc->gdb_adjust_breakpoint(cpu, pc); | |
382 | } | |
383 | ||
384 | bp = g_malloc(sizeof(*bp)); | |
385 | ||
386 | bp->pc = pc; | |
387 | bp->flags = flags; | |
388 | ||
389 | /* keep all GDB-injected breakpoints in front */ | |
390 | if (flags & BP_GDB) { | |
391 | QTAILQ_INSERT_HEAD(&cpu->breakpoints, bp, entry); | |
392 | } else { | |
393 | QTAILQ_INSERT_TAIL(&cpu->breakpoints, bp, entry); | |
394 | } | |
395 | ||
396 | if (breakpoint) { | |
397 | *breakpoint = bp; | |
398 | } | |
399 | ||
400 | trace_breakpoint_insert(cpu->cpu_index, pc, flags); | |
401 | return 0; | |
402 | } | |
403 | ||
404 | /* Remove a specific breakpoint. */ | |
405 | int cpu_breakpoint_remove(CPUState *cpu, vaddr pc, int flags) | |
406 | { | |
407 | CPUClass *cc = CPU_GET_CLASS(cpu); | |
408 | CPUBreakpoint *bp; | |
409 | ||
410 | if (cc->gdb_adjust_breakpoint) { | |
411 | pc = cc->gdb_adjust_breakpoint(cpu, pc); | |
412 | } | |
413 | ||
414 | QTAILQ_FOREACH(bp, &cpu->breakpoints, entry) { | |
415 | if (bp->pc == pc && bp->flags == flags) { | |
416 | cpu_breakpoint_remove_by_ref(cpu, bp); | |
417 | return 0; | |
418 | } | |
419 | } | |
420 | return -ENOENT; | |
421 | } | |
422 | ||
423 | /* Remove a specific breakpoint by reference. */ | |
424 | void cpu_breakpoint_remove_by_ref(CPUState *cpu, CPUBreakpoint *bp) | |
425 | { | |
426 | QTAILQ_REMOVE(&cpu->breakpoints, bp, entry); | |
427 | ||
428 | trace_breakpoint_remove(cpu->cpu_index, bp->pc, bp->flags); | |
429 | g_free(bp); | |
430 | } | |
431 | ||
432 | /* Remove all matching breakpoints. */ | |
433 | void cpu_breakpoint_remove_all(CPUState *cpu, int mask) | |
434 | { | |
435 | CPUBreakpoint *bp, *next; | |
436 | ||
437 | QTAILQ_FOREACH_SAFE(bp, &cpu->breakpoints, entry, next) { | |
438 | if (bp->flags & mask) { | |
439 | cpu_breakpoint_remove_by_ref(cpu, bp); | |
440 | } | |
441 | } | |
442 | } |