1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 *
4 * Copyright (C) 2016 ARM Limited
5 */
6
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9 #include <linux/atomic.h>
10 #include <linux/completion.h>
11 #include <linux/cpu.h>
12 #include <linux/cpuidle.h>
13 #include <linux/cpu_pm.h>
14 #include <linux/kernel.h>
15 #include <linux/kthread.h>
16 #include <uapi/linux/sched/types.h>
17 #include <linux/module.h>
18 #include <linux/preempt.h>
19 #include <linux/psci.h>
20 #include <linux/slab.h>
21 #include <linux/tick.h>
22 #include <linux/topology.h>
23
24 #include <asm/cpuidle.h>
25
26 #include <uapi/linux/psci.h>
27
28 #define NUM_SUSPEND_CYCLE (10)
29
30 static unsigned int nb_available_cpus;
31 static int tos_resident_cpu = -1;
32
33 static atomic_t nb_active_threads;
34 static struct completion suspend_threads_started =
35 COMPLETION_INITIALIZER(suspend_threads_started);
36 static struct completion suspend_threads_done =
37 COMPLETION_INITIALIZER(suspend_threads_done);
38
39 /*
40 * We assume that PSCI operations are used if they are available. This is not
41 * necessarily true on arm64, since the decision is based on the
42 * "enable-method" property of each CPU in the DT, but given that there is no
43 * arch-specific way to check this, we assume that the DT is sensible.
44 */
psci_ops_check(void)45 static int psci_ops_check(void)
46 {
47 int migrate_type = -1;
48 int cpu;
49
50 if (!(psci_ops.cpu_off && psci_ops.cpu_on && psci_ops.cpu_suspend)) {
51 pr_warn("Missing PSCI operations, aborting tests\n");
52 return -EOPNOTSUPP;
53 }
54
55 if (psci_ops.migrate_info_type)
56 migrate_type = psci_ops.migrate_info_type();
57
58 if (migrate_type == PSCI_0_2_TOS_UP_MIGRATE ||
59 migrate_type == PSCI_0_2_TOS_UP_NO_MIGRATE) {
60 /* There is a UP Trusted OS, find on which core it resides. */
61 for_each_online_cpu(cpu)
62 if (psci_tos_resident_on(cpu)) {
63 tos_resident_cpu = cpu;
64 break;
65 }
66 if (tos_resident_cpu == -1)
67 pr_warn("UP Trusted OS resides on no online CPU\n");
68 }
69
70 return 0;
71 }
72
73 /*
74 * offlined_cpus is a temporary array but passing it as an argument avoids
75 * multiple allocations.
76 */
down_and_up_cpus(const struct cpumask * cpus,struct cpumask * offlined_cpus)77 static unsigned int down_and_up_cpus(const struct cpumask *cpus,
78 struct cpumask *offlined_cpus)
79 {
80 int cpu;
81 int err = 0;
82
83 cpumask_clear(offlined_cpus);
84
85 /* Try to power down all CPUs in the mask. */
86 for_each_cpu(cpu, cpus) {
87 int ret = remove_cpu(cpu);
88
89 /*
90 * cpu_down() checks the number of online CPUs before the TOS
91 * resident CPU.
92 */
93 if (cpumask_weight(offlined_cpus) + 1 == nb_available_cpus) {
94 if (ret != -EBUSY) {
95 pr_err("Unexpected return code %d while trying "
96 "to power down last online CPU %d\n",
97 ret, cpu);
98 ++err;
99 }
100 } else if (cpu == tos_resident_cpu) {
101 if (ret != -EPERM) {
102 pr_err("Unexpected return code %d while trying "
103 "to power down TOS resident CPU %d\n",
104 ret, cpu);
105 ++err;
106 }
107 } else if (ret != 0) {
108 pr_err("Error occurred (%d) while trying "
109 "to power down CPU %d\n", ret, cpu);
110 ++err;
111 }
112
113 if (ret == 0)
114 cpumask_set_cpu(cpu, offlined_cpus);
115 }
116
117 /* Try to power up all the CPUs that have been offlined. */
118 for_each_cpu(cpu, offlined_cpus) {
119 int ret = add_cpu(cpu);
120
121 if (ret != 0) {
122 pr_err("Error occurred (%d) while trying "
123 "to power up CPU %d\n", ret, cpu);
124 ++err;
125 } else {
126 cpumask_clear_cpu(cpu, offlined_cpus);
127 }
128 }
129
130 /*
131 * Something went bad at some point and some CPUs could not be turned
132 * back on.
133 */
134 WARN_ON(!cpumask_empty(offlined_cpus) ||
135 num_online_cpus() != nb_available_cpus);
136
137 return err;
138 }
139
free_cpu_groups(int num,cpumask_var_t ** pcpu_groups)140 static void free_cpu_groups(int num, cpumask_var_t **pcpu_groups)
141 {
142 int i;
143 cpumask_var_t *cpu_groups = *pcpu_groups;
144
145 for (i = 0; i < num; ++i)
146 free_cpumask_var(cpu_groups[i]);
147 kfree(cpu_groups);
148 }
149
alloc_init_cpu_groups(cpumask_var_t ** pcpu_groups)150 static int alloc_init_cpu_groups(cpumask_var_t **pcpu_groups)
151 {
152 int num_groups = 0;
153 cpumask_var_t tmp, *cpu_groups;
154
155 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
156 return -ENOMEM;
157
158 cpu_groups = kcalloc(nb_available_cpus, sizeof(*cpu_groups),
159 GFP_KERNEL);
160 if (!cpu_groups) {
161 free_cpumask_var(tmp);
162 return -ENOMEM;
163 }
164
165 cpumask_copy(tmp, cpu_online_mask);
166
167 while (!cpumask_empty(tmp)) {
168 const struct cpumask *cpu_group =
169 topology_core_cpumask(cpumask_any(tmp));
170
171 if (!alloc_cpumask_var(&cpu_groups[num_groups], GFP_KERNEL)) {
172 free_cpumask_var(tmp);
173 free_cpu_groups(num_groups, &cpu_groups);
174 return -ENOMEM;
175 }
176 cpumask_copy(cpu_groups[num_groups++], cpu_group);
177 cpumask_andnot(tmp, tmp, cpu_group);
178 }
179
180 free_cpumask_var(tmp);
181 *pcpu_groups = cpu_groups;
182
183 return num_groups;
184 }
185
hotplug_tests(void)186 static int hotplug_tests(void)
187 {
188 int i, nb_cpu_group, err = -ENOMEM;
189 cpumask_var_t offlined_cpus, *cpu_groups;
190 char *page_buf;
191
192 if (!alloc_cpumask_var(&offlined_cpus, GFP_KERNEL))
193 return err;
194
195 nb_cpu_group = alloc_init_cpu_groups(&cpu_groups);
196 if (nb_cpu_group < 0)
197 goto out_free_cpus;
198 page_buf = (char *)__get_free_page(GFP_KERNEL);
199 if (!page_buf)
200 goto out_free_cpu_groups;
201
202 /*
203 * Of course the last CPU cannot be powered down and cpu_down() should
204 * refuse doing that.
205 */
206 pr_info("Trying to turn off and on again all CPUs\n");
207 err = down_and_up_cpus(cpu_online_mask, offlined_cpus);
208
209 /*
210 * Take down CPUs by cpu group this time. When the last CPU is turned
211 * off, the cpu group itself should shut down.
212 */
213 for (i = 0; i < nb_cpu_group; ++i) {
214 ssize_t len = cpumap_print_to_pagebuf(true, page_buf,
215 cpu_groups[i]);
216 /* Remove trailing newline. */
217 page_buf[len - 1] = '\0';
218 pr_info("Trying to turn off and on again group %d (CPUs %s)\n",
219 i, page_buf);
220 err += down_and_up_cpus(cpu_groups[i], offlined_cpus);
221 }
222
223 free_page((unsigned long)page_buf);
224 out_free_cpu_groups:
225 free_cpu_groups(nb_cpu_group, &cpu_groups);
226 out_free_cpus:
227 free_cpumask_var(offlined_cpus);
228 return err;
229 }
230
dummy_callback(struct timer_list * unused)231 static void dummy_callback(struct timer_list *unused) {}
232
suspend_cpu(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)233 static int suspend_cpu(struct cpuidle_device *dev,
234 struct cpuidle_driver *drv, int index)
235 {
236 struct cpuidle_state *state = &drv->states[index];
237 bool broadcast = state->flags & CPUIDLE_FLAG_TIMER_STOP;
238 int ret;
239
240 arch_cpu_idle_enter();
241
242 if (broadcast) {
243 /*
244 * The local timer will be shut down, we need to enter tick
245 * broadcast.
246 */
247 ret = tick_broadcast_enter();
248 if (ret) {
249 /*
250 * In the absence of hardware broadcast mechanism,
251 * this CPU might be used to broadcast wakeups, which
252 * may be why entering tick broadcast has failed.
253 * There is little the kernel can do to work around
254 * that, so enter WFI instead (idle state 0).
255 */
256 cpu_do_idle();
257 ret = 0;
258 goto out_arch_exit;
259 }
260 }
261
262 ret = state->enter(dev, drv, index);
263
264 if (broadcast)
265 tick_broadcast_exit();
266
267 out_arch_exit:
268 arch_cpu_idle_exit();
269
270 return ret;
271 }
272
suspend_test_thread(void * arg)273 static int suspend_test_thread(void *arg)
274 {
275 int cpu = (long)arg;
276 int i, nb_suspend = 0, nb_shallow_sleep = 0, nb_err = 0;
277 struct cpuidle_device *dev;
278 struct cpuidle_driver *drv;
279 /* No need for an actual callback, we just want to wake up the CPU. */
280 struct timer_list wakeup_timer;
281
282 /* Wait for the main thread to give the start signal. */
283 wait_for_completion(&suspend_threads_started);
284
285 /* Set maximum priority to preempt all other threads on this CPU. */
286 sched_set_fifo(current);
287
288 dev = this_cpu_read(cpuidle_devices);
289 drv = cpuidle_get_cpu_driver(dev);
290
291 pr_info("CPU %d entering suspend cycles, states 1 through %d\n",
292 cpu, drv->state_count - 1);
293
294 timer_setup_on_stack(&wakeup_timer, dummy_callback, 0);
295 for (i = 0; i < NUM_SUSPEND_CYCLE; ++i) {
296 int index;
297 /*
298 * Test all possible states, except 0 (which is usually WFI and
299 * doesn't use PSCI).
300 */
301 for (index = 1; index < drv->state_count; ++index) {
302 int ret;
303 struct cpuidle_state *state = &drv->states[index];
304
305 /*
306 * Set the timer to wake this CPU up in some time (which
307 * should be largely sufficient for entering suspend).
308 * If the local tick is disabled when entering suspend,
309 * suspend_cpu() takes care of switching to a broadcast
310 * tick, so the timer will still wake us up.
311 */
312 mod_timer(&wakeup_timer, jiffies +
313 usecs_to_jiffies(state->target_residency));
314
315 /* IRQs must be disabled during suspend operations. */
316 local_irq_disable();
317
318 ret = suspend_cpu(dev, drv, index);
319
320 /*
321 * We have woken up. Re-enable IRQs to handle any
322 * pending interrupt, do not wait until the end of the
323 * loop.
324 */
325 local_irq_enable();
326
327 if (ret == index) {
328 ++nb_suspend;
329 } else if (ret >= 0) {
330 /* We did not enter the expected state. */
331 ++nb_shallow_sleep;
332 } else {
333 pr_err("Failed to suspend CPU %d: error %d "
334 "(requested state %d, cycle %d)\n",
335 cpu, ret, index, i);
336 ++nb_err;
337 }
338 }
339 }
340
341 /*
342 * Disable the timer to make sure that the timer will not trigger
343 * later.
344 */
345 del_timer(&wakeup_timer);
346 destroy_timer_on_stack(&wakeup_timer);
347
348 if (atomic_dec_return_relaxed(&nb_active_threads) == 0)
349 complete(&suspend_threads_done);
350
351 for (;;) {
352 /* Needs to be set first to avoid missing a wakeup. */
353 set_current_state(TASK_INTERRUPTIBLE);
354 if (kthread_should_park())
355 break;
356 schedule();
357 }
358
359 pr_info("CPU %d suspend test results: success %d, shallow states %d, errors %d\n",
360 cpu, nb_suspend, nb_shallow_sleep, nb_err);
361
362 kthread_parkme();
363
364 return nb_err;
365 }
366
suspend_tests(void)367 static int suspend_tests(void)
368 {
369 int i, cpu, err = 0;
370 struct task_struct **threads;
371 int nb_threads = 0;
372
373 threads = kmalloc_array(nb_available_cpus, sizeof(*threads),
374 GFP_KERNEL);
375 if (!threads)
376 return -ENOMEM;
377
378 /*
379 * Stop cpuidle to prevent the idle tasks from entering a deep sleep
380 * mode, as it might interfere with the suspend threads on other CPUs.
381 * This does not prevent the suspend threads from using cpuidle (only
382 * the idle tasks check this status). Take the idle lock so that
383 * the cpuidle driver and device look-up can be carried out safely.
384 */
385 cpuidle_pause_and_lock();
386
387 for_each_online_cpu(cpu) {
388 struct task_struct *thread;
389 /* Check that cpuidle is available on that CPU. */
390 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
391 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
392
393 if (!dev || !drv) {
394 pr_warn("cpuidle not available on CPU %d, ignoring\n",
395 cpu);
396 continue;
397 }
398
399 thread = kthread_create_on_cpu(suspend_test_thread,
400 (void *)(long)cpu, cpu,
401 "psci_suspend_test");
402 if (IS_ERR(thread))
403 pr_err("Failed to create kthread on CPU %d\n", cpu);
404 else
405 threads[nb_threads++] = thread;
406 }
407
408 if (nb_threads < 1) {
409 err = -ENODEV;
410 goto out;
411 }
412
413 atomic_set(&nb_active_threads, nb_threads);
414
415 /*
416 * Wake up the suspend threads. To avoid the main thread being preempted
417 * before all the threads have been unparked, the suspend threads will
418 * wait for the completion of suspend_threads_started.
419 */
420 for (i = 0; i < nb_threads; ++i)
421 wake_up_process(threads[i]);
422 complete_all(&suspend_threads_started);
423
424 wait_for_completion(&suspend_threads_done);
425
426
427 /* Stop and destroy all threads, get return status. */
428 for (i = 0; i < nb_threads; ++i) {
429 err += kthread_park(threads[i]);
430 err += kthread_stop(threads[i]);
431 }
432 out:
433 cpuidle_resume_and_unlock();
434 kfree(threads);
435 return err;
436 }
437
psci_checker(void)438 static int __init psci_checker(void)
439 {
440 int ret;
441
442 /*
443 * Since we're in an initcall, we assume that all the CPUs that all
444 * CPUs that can be onlined have been onlined.
445 *
446 * The tests assume that hotplug is enabled but nobody else is using it,
447 * otherwise the results will be unpredictable. However, since there
448 * is no userspace yet in initcalls, that should be fine, as long as
449 * no torture test is running at the same time (see Kconfig).
450 */
451 nb_available_cpus = num_online_cpus();
452
453 /* Check PSCI operations are set up and working. */
454 ret = psci_ops_check();
455 if (ret)
456 return ret;
457
458 pr_info("PSCI checker started using %u CPUs\n", nb_available_cpus);
459
460 pr_info("Starting hotplug tests\n");
461 ret = hotplug_tests();
462 if (ret == 0)
463 pr_info("Hotplug tests passed OK\n");
464 else if (ret > 0)
465 pr_err("%d error(s) encountered in hotplug tests\n", ret);
466 else {
467 pr_err("Out of memory\n");
468 return ret;
469 }
470
471 pr_info("Starting suspend tests (%d cycles per state)\n",
472 NUM_SUSPEND_CYCLE);
473 ret = suspend_tests();
474 if (ret == 0)
475 pr_info("Suspend tests passed OK\n");
476 else if (ret > 0)
477 pr_err("%d error(s) encountered in suspend tests\n", ret);
478 else {
479 switch (ret) {
480 case -ENOMEM:
481 pr_err("Out of memory\n");
482 break;
483 case -ENODEV:
484 pr_warn("Could not start suspend tests on any CPU\n");
485 break;
486 }
487 }
488
489 pr_info("PSCI checker completed\n");
490 return ret < 0 ? ret : 0;
491 }
492 late_initcall(psci_checker);
493
