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
30static unsigned int nb_available_cpus;
31static int tos_resident_cpu = -1;
32
33static atomic_t nb_active_threads;
34static struct completion suspend_threads_started =
35	COMPLETION_INITIALIZER(suspend_threads_started);
36static 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 */
45static 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 */
77static 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
140static 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
150static 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
186static 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);
224out_free_cpu_groups:
225	free_cpu_groups(nb_cpu_group, &cpu_groups);
226out_free_cpus:
227	free_cpumask_var(offlined_cpus);
228	return err;
229}
230
231static void dummy_callback(struct timer_list *unused) {}
232
233static 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
267out_arch_exit:
268	arch_cpu_idle_exit();
269
270	return ret;
271}
272
273static 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
367static 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
438static 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}
492late_initcall(psci_checker);
493