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 = kzalloc_objs(*cpu_groups, nb_available_cpus);
159 if (!cpu_groups) {
160 free_cpumask_var(tmp);
161 return -ENOMEM;
162 }
163
164 cpumask_copy(tmp, cpu_online_mask);
165
166 while (!cpumask_empty(tmp)) {
167 const struct cpumask *cpu_group =
168 topology_core_cpumask(cpumask_any(tmp));
169
170 if (!alloc_cpumask_var(&cpu_groups[num_groups], GFP_KERNEL)) {
171 free_cpumask_var(tmp);
172 free_cpu_groups(num_groups, &cpu_groups);
173 return -ENOMEM;
174 }
175 cpumask_copy(cpu_groups[num_groups++], cpu_group);
176 cpumask_andnot(tmp, tmp, cpu_group);
177 }
178
179 free_cpumask_var(tmp);
180 *pcpu_groups = cpu_groups;
181
182 return num_groups;
183 }
184
hotplug_tests(void)185 static int hotplug_tests(void)
186 {
187 int i, nb_cpu_group, err = -ENOMEM;
188 cpumask_var_t offlined_cpus, *cpu_groups;
189
190 if (!alloc_cpumask_var(&offlined_cpus, GFP_KERNEL))
191 return err;
192
193 nb_cpu_group = alloc_init_cpu_groups(&cpu_groups);
194 if (nb_cpu_group < 0)
195 goto out_free_cpus;
196 /*
197 * Of course the last CPU cannot be powered down and cpu_down() should
198 * refuse doing that.
199 */
200 pr_info("Trying to turn off and on again all CPUs\n");
201 err = down_and_up_cpus(cpu_online_mask, offlined_cpus);
202
203 /*
204 * Take down CPUs by cpu group this time. When the last CPU is turned
205 * off, the cpu group itself should shut down.
206 */
207 for (i = 0; i < nb_cpu_group; ++i) {
208 pr_info("Trying to turn off and on again group %d (CPUs %*pbl)\n",
209 i, cpumask_pr_args(cpu_groups[i]));
210 err += down_and_up_cpus(cpu_groups[i], offlined_cpus);
211 }
212
213 free_cpu_groups(nb_cpu_group, &cpu_groups);
214 out_free_cpus:
215 free_cpumask_var(offlined_cpus);
216 return err;
217 }
218
dummy_callback(struct timer_list * unused)219 static void dummy_callback(struct timer_list *unused) {}
220
suspend_cpu(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)221 static int suspend_cpu(struct cpuidle_device *dev,
222 struct cpuidle_driver *drv, int index)
223 {
224 struct cpuidle_state *state = &drv->states[index];
225 bool broadcast = state->flags & CPUIDLE_FLAG_TIMER_STOP;
226 int ret;
227
228 arch_cpu_idle_enter();
229
230 if (broadcast) {
231 /*
232 * The local timer will be shut down, we need to enter tick
233 * broadcast.
234 */
235 ret = tick_broadcast_enter();
236 if (ret) {
237 /*
238 * In the absence of hardware broadcast mechanism,
239 * this CPU might be used to broadcast wakeups, which
240 * may be why entering tick broadcast has failed.
241 * There is little the kernel can do to work around
242 * that, so enter WFI instead (idle state 0).
243 */
244 cpu_do_idle();
245 ret = 0;
246 goto out_arch_exit;
247 }
248 }
249
250 ret = state->enter(dev, drv, index);
251
252 if (broadcast)
253 tick_broadcast_exit();
254
255 out_arch_exit:
256 arch_cpu_idle_exit();
257
258 return ret;
259 }
260
suspend_test_thread(void * arg)261 static int suspend_test_thread(void *arg)
262 {
263 int cpu = (long)arg;
264 int i, nb_suspend = 0, nb_shallow_sleep = 0, nb_err = 0;
265 struct cpuidle_device *dev;
266 struct cpuidle_driver *drv;
267 /* No need for an actual callback, we just want to wake up the CPU. */
268 struct timer_list wakeup_timer;
269
270 /* Wait for the main thread to give the start signal. */
271 wait_for_completion(&suspend_threads_started);
272
273 /* Set maximum priority to preempt all other threads on this CPU. */
274 sched_set_fifo(current);
275
276 dev = this_cpu_read(cpuidle_devices);
277 drv = cpuidle_get_cpu_driver(dev);
278
279 pr_info("CPU %d entering suspend cycles, states 1 through %d\n",
280 cpu, drv->state_count - 1);
281
282 timer_setup_on_stack(&wakeup_timer, dummy_callback, 0);
283 for (i = 0; i < NUM_SUSPEND_CYCLE; ++i) {
284 int index;
285 /*
286 * Test all possible states, except 0 (which is usually WFI and
287 * doesn't use PSCI).
288 */
289 for (index = 1; index < drv->state_count; ++index) {
290 int ret;
291 struct cpuidle_state *state = &drv->states[index];
292
293 /*
294 * Set the timer to wake this CPU up in some time (which
295 * should be largely sufficient for entering suspend).
296 * If the local tick is disabled when entering suspend,
297 * suspend_cpu() takes care of switching to a broadcast
298 * tick, so the timer will still wake us up.
299 */
300 mod_timer(&wakeup_timer, jiffies +
301 usecs_to_jiffies(state->target_residency));
302
303 /* IRQs must be disabled during suspend operations. */
304 local_irq_disable();
305
306 ret = suspend_cpu(dev, drv, index);
307
308 /*
309 * We have woken up. Re-enable IRQs to handle any
310 * pending interrupt, do not wait until the end of the
311 * loop.
312 */
313 local_irq_enable();
314
315 if (ret == index) {
316 ++nb_suspend;
317 } else if (ret >= 0) {
318 /* We did not enter the expected state. */
319 ++nb_shallow_sleep;
320 } else {
321 pr_err("Failed to suspend CPU %d: error %d "
322 "(requested state %d, cycle %d)\n",
323 cpu, ret, index, i);
324 ++nb_err;
325 }
326 }
327 }
328
329 /*
330 * Disable the timer to make sure that the timer will not trigger
331 * later.
332 */
333 timer_delete(&wakeup_timer);
334 timer_destroy_on_stack(&wakeup_timer);
335
336 if (atomic_dec_return_relaxed(&nb_active_threads) == 0)
337 complete(&suspend_threads_done);
338
339 for (;;) {
340 /* Needs to be set first to avoid missing a wakeup. */
341 set_current_state(TASK_INTERRUPTIBLE);
342 if (kthread_should_park())
343 break;
344 schedule();
345 }
346
347 pr_info("CPU %d suspend test results: success %d, shallow states %d, errors %d\n",
348 cpu, nb_suspend, nb_shallow_sleep, nb_err);
349
350 kthread_parkme();
351
352 return nb_err;
353 }
354
suspend_tests(void)355 static int suspend_tests(void)
356 {
357 int i, cpu, err = 0;
358 struct task_struct **threads;
359 int nb_threads = 0;
360
361 threads = kmalloc_objs(*threads, nb_available_cpus);
362 if (!threads)
363 return -ENOMEM;
364
365 /*
366 * Stop cpuidle to prevent the idle tasks from entering a deep sleep
367 * mode, as it might interfere with the suspend threads on other CPUs.
368 * This does not prevent the suspend threads from using cpuidle (only
369 * the idle tasks check this status). Take the idle lock so that
370 * the cpuidle driver and device look-up can be carried out safely.
371 */
372 cpuidle_pause_and_lock();
373
374 for_each_online_cpu(cpu) {
375 struct task_struct *thread;
376 /* Check that cpuidle is available on that CPU. */
377 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
378 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
379
380 if (!dev || !drv) {
381 pr_warn("cpuidle not available on CPU %d, ignoring\n",
382 cpu);
383 continue;
384 }
385
386 thread = kthread_create_on_cpu(suspend_test_thread,
387 (void *)(long)cpu, cpu,
388 "psci_suspend_test");
389 if (IS_ERR(thread))
390 pr_err("Failed to create kthread on CPU %d\n", cpu);
391 else
392 threads[nb_threads++] = thread;
393 }
394
395 if (nb_threads < 1) {
396 err = -ENODEV;
397 goto out;
398 }
399
400 atomic_set(&nb_active_threads, nb_threads);
401
402 /*
403 * Wake up the suspend threads. To avoid the main thread being preempted
404 * before all the threads have been unparked, the suspend threads will
405 * wait for the completion of suspend_threads_started.
406 */
407 for (i = 0; i < nb_threads; ++i)
408 wake_up_process(threads[i]);
409 complete_all(&suspend_threads_started);
410
411 wait_for_completion(&suspend_threads_done);
412
413
414 /* Stop and destroy all threads, get return status. */
415 for (i = 0; i < nb_threads; ++i) {
416 err += kthread_park(threads[i]);
417 err += kthread_stop(threads[i]);
418 }
419 out:
420 cpuidle_resume_and_unlock();
421 kfree(threads);
422 return err;
423 }
424
psci_checker(void)425 static int __init psci_checker(void)
426 {
427 int ret;
428
429 /*
430 * Since we're in an initcall, we assume that all the CPUs that all
431 * CPUs that can be onlined have been onlined.
432 *
433 * The tests assume that hotplug is enabled but nobody else is using it,
434 * otherwise the results will be unpredictable. However, since there
435 * is no userspace yet in initcalls, that should be fine, as long as
436 * no torture test is running at the same time (see Kconfig).
437 */
438 nb_available_cpus = num_online_cpus();
439
440 /* Check PSCI operations are set up and working. */
441 ret = psci_ops_check();
442 if (ret)
443 return ret;
444
445 pr_info("PSCI checker started using %u CPUs\n", nb_available_cpus);
446
447 pr_info("Starting hotplug tests\n");
448 ret = hotplug_tests();
449 if (ret == 0)
450 pr_info("Hotplug tests passed OK\n");
451 else if (ret > 0)
452 pr_err("%d error(s) encountered in hotplug tests\n", ret);
453 else {
454 pr_err("Out of memory\n");
455 return ret;
456 }
457
458 pr_info("Starting suspend tests (%d cycles per state)\n",
459 NUM_SUSPEND_CYCLE);
460 ret = suspend_tests();
461 if (ret == 0)
462 pr_info("Suspend tests passed OK\n");
463 else if (ret > 0)
464 pr_err("%d error(s) encountered in suspend tests\n", ret);
465 else {
466 switch (ret) {
467 case -ENOMEM:
468 pr_err("Out of memory\n");
469 break;
470 case -ENODEV:
471 pr_warn("Could not start suspend tests on any CPU\n");
472 break;
473 }
474 }
475
476 pr_info("PSCI checker completed\n");
477 return ret < 0 ? ret : 0;
478 }
479 late_initcall(psci_checker);
480