1 /*
2  * This program is free software; you can redistribute it and/or modify
3  * it under the terms of the GNU General Public License version 2 as
4  * published by the Free Software Foundation.
5  *
6  * This program is distributed in the hope that it will be useful,
7  * but WITHOUT ANY WARRANTY; without even the implied warranty of
8  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
9  * GNU General Public License for more details.
10  *
11  * Copyright (C) 2016 ARM Limited
12  */
13 
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15 
16 #include <linux/atomic.h>
17 #include <linux/completion.h>
18 #include <linux/cpu.h>
19 #include <linux/cpuidle.h>
20 #include <linux/cpu_pm.h>
21 #include <linux/kernel.h>
22 #include <linux/kthread.h>
23 #include <uapi/linux/sched/types.h>
24 #include <linux/module.h>
25 #include <linux/preempt.h>
26 #include <linux/psci.h>
27 #include <linux/slab.h>
28 #include <linux/tick.h>
29 #include <linux/topology.h>
30 
31 #include <asm/cpuidle.h>
32 
33 #include <uapi/linux/psci.h>
34 
35 #define NUM_SUSPEND_CYCLE (10)
36 
37 static unsigned int nb_available_cpus;
38 static int tos_resident_cpu = -1;
39 
40 static atomic_t nb_active_threads;
41 static struct completion suspend_threads_started =
42 	COMPLETION_INITIALIZER(suspend_threads_started);
43 static struct completion suspend_threads_done =
44 	COMPLETION_INITIALIZER(suspend_threads_done);
45 
46 /*
47  * We assume that PSCI operations are used if they are available. This is not
48  * necessarily true on arm64, since the decision is based on the
49  * "enable-method" property of each CPU in the DT, but given that there is no
50  * arch-specific way to check this, we assume that the DT is sensible.
51  */
52 static int psci_ops_check(void)
53 {
54 	int migrate_type = -1;
55 	int cpu;
56 
57 	if (!(psci_ops.cpu_off && psci_ops.cpu_on && psci_ops.cpu_suspend)) {
58 		pr_warn("Missing PSCI operations, aborting tests\n");
59 		return -EOPNOTSUPP;
60 	}
61 
62 	if (psci_ops.migrate_info_type)
63 		migrate_type = psci_ops.migrate_info_type();
64 
65 	if (migrate_type == PSCI_0_2_TOS_UP_MIGRATE ||
66 	    migrate_type == PSCI_0_2_TOS_UP_NO_MIGRATE) {
67 		/* There is a UP Trusted OS, find on which core it resides. */
68 		for_each_online_cpu(cpu)
69 			if (psci_tos_resident_on(cpu)) {
70 				tos_resident_cpu = cpu;
71 				break;
72 			}
73 		if (tos_resident_cpu == -1)
74 			pr_warn("UP Trusted OS resides on no online CPU\n");
75 	}
76 
77 	return 0;
78 }
79 
80 /*
81  * offlined_cpus is a temporary array but passing it as an argument avoids
82  * multiple allocations.
83  */
84 static unsigned int down_and_up_cpus(const struct cpumask *cpus,
85 				     struct cpumask *offlined_cpus)
86 {
87 	int cpu;
88 	int err = 0;
89 
90 	cpumask_clear(offlined_cpus);
91 
92 	/* Try to power down all CPUs in the mask. */
93 	for_each_cpu(cpu, cpus) {
94 		int ret = cpu_down(cpu);
95 
96 		/*
97 		 * cpu_down() checks the number of online CPUs before the TOS
98 		 * resident CPU.
99 		 */
100 		if (cpumask_weight(offlined_cpus) + 1 == nb_available_cpus) {
101 			if (ret != -EBUSY) {
102 				pr_err("Unexpected return code %d while trying "
103 				       "to power down last online CPU %d\n",
104 				       ret, cpu);
105 				++err;
106 			}
107 		} else if (cpu == tos_resident_cpu) {
108 			if (ret != -EPERM) {
109 				pr_err("Unexpected return code %d while trying "
110 				       "to power down TOS resident CPU %d\n",
111 				       ret, cpu);
112 				++err;
113 			}
114 		} else if (ret != 0) {
115 			pr_err("Error occurred (%d) while trying "
116 			       "to power down CPU %d\n", ret, cpu);
117 			++err;
118 		}
119 
120 		if (ret == 0)
121 			cpumask_set_cpu(cpu, offlined_cpus);
122 	}
123 
124 	/* Try to power up all the CPUs that have been offlined. */
125 	for_each_cpu(cpu, offlined_cpus) {
126 		int ret = cpu_up(cpu);
127 
128 		if (ret != 0) {
129 			pr_err("Error occurred (%d) while trying "
130 			       "to power up CPU %d\n", ret, cpu);
131 			++err;
132 		} else {
133 			cpumask_clear_cpu(cpu, offlined_cpus);
134 		}
135 	}
136 
137 	/*
138 	 * Something went bad at some point and some CPUs could not be turned
139 	 * back on.
140 	 */
141 	WARN_ON(!cpumask_empty(offlined_cpus) ||
142 		num_online_cpus() != nb_available_cpus);
143 
144 	return err;
145 }
146 
147 static void free_cpu_groups(int num, cpumask_var_t **pcpu_groups)
148 {
149 	int i;
150 	cpumask_var_t *cpu_groups = *pcpu_groups;
151 
152 	for (i = 0; i < num; ++i)
153 		free_cpumask_var(cpu_groups[i]);
154 	kfree(cpu_groups);
155 }
156 
157 static int alloc_init_cpu_groups(cpumask_var_t **pcpu_groups)
158 {
159 	int num_groups = 0;
160 	cpumask_var_t tmp, *cpu_groups;
161 
162 	if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
163 		return -ENOMEM;
164 
165 	cpu_groups = kcalloc(nb_available_cpus, sizeof(cpu_groups),
166 			     GFP_KERNEL);
167 	if (!cpu_groups)
168 		return -ENOMEM;
169 
170 	cpumask_copy(tmp, cpu_online_mask);
171 
172 	while (!cpumask_empty(tmp)) {
173 		const struct cpumask *cpu_group =
174 			topology_core_cpumask(cpumask_any(tmp));
175 
176 		if (!alloc_cpumask_var(&cpu_groups[num_groups], GFP_KERNEL)) {
177 			free_cpu_groups(num_groups, &cpu_groups);
178 			return -ENOMEM;
179 		}
180 		cpumask_copy(cpu_groups[num_groups++], cpu_group);
181 		cpumask_andnot(tmp, tmp, cpu_group);
182 	}
183 
184 	free_cpumask_var(tmp);
185 	*pcpu_groups = cpu_groups;
186 
187 	return num_groups;
188 }
189 
190 static int hotplug_tests(void)
191 {
192 	int i, nb_cpu_group, err = -ENOMEM;
193 	cpumask_var_t offlined_cpus, *cpu_groups;
194 	char *page_buf;
195 
196 	if (!alloc_cpumask_var(&offlined_cpus, GFP_KERNEL))
197 		return err;
198 
199 	nb_cpu_group = alloc_init_cpu_groups(&cpu_groups);
200 	if (nb_cpu_group < 0)
201 		goto out_free_cpus;
202 	page_buf = (char *)__get_free_page(GFP_KERNEL);
203 	if (!page_buf)
204 		goto out_free_cpu_groups;
205 
206 	err = 0;
207 	/*
208 	 * Of course the last CPU cannot be powered down and cpu_down() should
209 	 * refuse doing that.
210 	 */
211 	pr_info("Trying to turn off and on again all CPUs\n");
212 	err += down_and_up_cpus(cpu_online_mask, offlined_cpus);
213 
214 	/*
215 	 * Take down CPUs by cpu group this time. When the last CPU is turned
216 	 * off, the cpu group itself should shut down.
217 	 */
218 	for (i = 0; i < nb_cpu_group; ++i) {
219 		ssize_t len = cpumap_print_to_pagebuf(true, page_buf,
220 						      cpu_groups[i]);
221 		/* Remove trailing newline. */
222 		page_buf[len - 1] = '\0';
223 		pr_info("Trying to turn off and on again group %d (CPUs %s)\n",
224 			i, page_buf);
225 		err += down_and_up_cpus(cpu_groups[i], offlined_cpus);
226 	}
227 
228 	free_page((unsigned long)page_buf);
229 out_free_cpu_groups:
230 	free_cpu_groups(nb_cpu_group, &cpu_groups);
231 out_free_cpus:
232 	free_cpumask_var(offlined_cpus);
233 	return err;
234 }
235 
236 static void dummy_callback(struct timer_list *unused) {}
237 
238 static int suspend_cpu(int index, bool broadcast)
239 {
240 	int ret;
241 
242 	arch_cpu_idle_enter();
243 
244 	if (broadcast) {
245 		/*
246 		 * The local timer will be shut down, we need to enter tick
247 		 * broadcast.
248 		 */
249 		ret = tick_broadcast_enter();
250 		if (ret) {
251 			/*
252 			 * In the absence of hardware broadcast mechanism,
253 			 * this CPU might be used to broadcast wakeups, which
254 			 * may be why entering tick broadcast has failed.
255 			 * There is little the kernel can do to work around
256 			 * that, so enter WFI instead (idle state 0).
257 			 */
258 			cpu_do_idle();
259 			ret = 0;
260 			goto out_arch_exit;
261 		}
262 	}
263 
264 	/*
265 	 * Replicate the common ARM cpuidle enter function
266 	 * (arm_enter_idle_state).
267 	 */
268 	ret = CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, index);
269 
270 	if (broadcast)
271 		tick_broadcast_exit();
272 
273 out_arch_exit:
274 	arch_cpu_idle_exit();
275 
276 	return ret;
277 }
278 
279 static int suspend_test_thread(void *arg)
280 {
281 	int cpu = (long)arg;
282 	int i, nb_suspend = 0, nb_shallow_sleep = 0, nb_err = 0;
283 	struct sched_param sched_priority = { .sched_priority = MAX_RT_PRIO-1 };
284 	struct cpuidle_device *dev;
285 	struct cpuidle_driver *drv;
286 	/* No need for an actual callback, we just want to wake up the CPU. */
287 	struct timer_list wakeup_timer;
288 
289 	/* Wait for the main thread to give the start signal. */
290 	wait_for_completion(&suspend_threads_started);
291 
292 	/* Set maximum priority to preempt all other threads on this CPU. */
293 	if (sched_setscheduler_nocheck(current, SCHED_FIFO, &sched_priority))
294 		pr_warn("Failed to set suspend thread scheduler on CPU %d\n",
295 			cpu);
296 
297 	dev = this_cpu_read(cpuidle_devices);
298 	drv = cpuidle_get_cpu_driver(dev);
299 
300 	pr_info("CPU %d entering suspend cycles, states 1 through %d\n",
301 		cpu, drv->state_count - 1);
302 
303 	timer_setup_on_stack(&wakeup_timer, dummy_callback, 0);
304 	for (i = 0; i < NUM_SUSPEND_CYCLE; ++i) {
305 		int index;
306 		/*
307 		 * Test all possible states, except 0 (which is usually WFI and
308 		 * doesn't use PSCI).
309 		 */
310 		for (index = 1; index < drv->state_count; ++index) {
311 			struct cpuidle_state *state = &drv->states[index];
312 			bool broadcast = state->flags & CPUIDLE_FLAG_TIMER_STOP;
313 			int ret;
314 
315 			/*
316 			 * Set the timer to wake this CPU up in some time (which
317 			 * should be largely sufficient for entering suspend).
318 			 * If the local tick is disabled when entering suspend,
319 			 * suspend_cpu() takes care of switching to a broadcast
320 			 * tick, so the timer will still wake us up.
321 			 */
322 			mod_timer(&wakeup_timer, jiffies +
323 				  usecs_to_jiffies(state->target_residency));
324 
325 			/* IRQs must be disabled during suspend operations. */
326 			local_irq_disable();
327 
328 			ret = suspend_cpu(index, broadcast);
329 
330 			/*
331 			 * We have woken up. Re-enable IRQs to handle any
332 			 * pending interrupt, do not wait until the end of the
333 			 * loop.
334 			 */
335 			local_irq_enable();
336 
337 			if (ret == index) {
338 				++nb_suspend;
339 			} else if (ret >= 0) {
340 				/* We did not enter the expected state. */
341 				++nb_shallow_sleep;
342 			} else {
343 				pr_err("Failed to suspend CPU %d: error %d "
344 				       "(requested state %d, cycle %d)\n",
345 				       cpu, ret, index, i);
346 				++nb_err;
347 			}
348 		}
349 	}
350 
351 	/*
352 	 * Disable the timer to make sure that the timer will not trigger
353 	 * later.
354 	 */
355 	del_timer(&wakeup_timer);
356 	destroy_timer_on_stack(&wakeup_timer);
357 
358 	if (atomic_dec_return_relaxed(&nb_active_threads) == 0)
359 		complete(&suspend_threads_done);
360 
361 	/* Give up on RT scheduling and wait for termination. */
362 	sched_priority.sched_priority = 0;
363 	if (sched_setscheduler_nocheck(current, SCHED_NORMAL, &sched_priority))
364 		pr_warn("Failed to set suspend thread scheduler on CPU %d\n",
365 			cpu);
366 	for (;;) {
367 		/* Needs to be set first to avoid missing a wakeup. */
368 		set_current_state(TASK_INTERRUPTIBLE);
369 		if (kthread_should_stop()) {
370 			__set_current_state(TASK_RUNNING);
371 			break;
372 		}
373 		schedule();
374 	}
375 
376 	pr_info("CPU %d suspend test results: success %d, shallow states %d, errors %d\n",
377 		cpu, nb_suspend, nb_shallow_sleep, nb_err);
378 
379 	return nb_err;
380 }
381 
382 static int suspend_tests(void)
383 {
384 	int i, cpu, err = 0;
385 	struct task_struct **threads;
386 	int nb_threads = 0;
387 
388 	threads = kmalloc_array(nb_available_cpus, sizeof(*threads),
389 				GFP_KERNEL);
390 	if (!threads)
391 		return -ENOMEM;
392 
393 	/*
394 	 * Stop cpuidle to prevent the idle tasks from entering a deep sleep
395 	 * mode, as it might interfere with the suspend threads on other CPUs.
396 	 * This does not prevent the suspend threads from using cpuidle (only
397 	 * the idle tasks check this status). Take the idle lock so that
398 	 * the cpuidle driver and device look-up can be carried out safely.
399 	 */
400 	cpuidle_pause_and_lock();
401 
402 	for_each_online_cpu(cpu) {
403 		struct task_struct *thread;
404 		/* Check that cpuidle is available on that CPU. */
405 		struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
406 		struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
407 
408 		if (!dev || !drv) {
409 			pr_warn("cpuidle not available on CPU %d, ignoring\n",
410 				cpu);
411 			continue;
412 		}
413 
414 		thread = kthread_create_on_cpu(suspend_test_thread,
415 					       (void *)(long)cpu, cpu,
416 					       "psci_suspend_test");
417 		if (IS_ERR(thread))
418 			pr_err("Failed to create kthread on CPU %d\n", cpu);
419 		else
420 			threads[nb_threads++] = thread;
421 	}
422 
423 	if (nb_threads < 1) {
424 		err = -ENODEV;
425 		goto out;
426 	}
427 
428 	atomic_set(&nb_active_threads, nb_threads);
429 
430 	/*
431 	 * Wake up the suspend threads. To avoid the main thread being preempted
432 	 * before all the threads have been unparked, the suspend threads will
433 	 * wait for the completion of suspend_threads_started.
434 	 */
435 	for (i = 0; i < nb_threads; ++i)
436 		wake_up_process(threads[i]);
437 	complete_all(&suspend_threads_started);
438 
439 	wait_for_completion(&suspend_threads_done);
440 
441 
442 	/* Stop and destroy all threads, get return status. */
443 	for (i = 0; i < nb_threads; ++i)
444 		err += kthread_stop(threads[i]);
445  out:
446 	cpuidle_resume_and_unlock();
447 	kfree(threads);
448 	return err;
449 }
450 
451 static int __init psci_checker(void)
452 {
453 	int ret;
454 
455 	/*
456 	 * Since we're in an initcall, we assume that all the CPUs that all
457 	 * CPUs that can be onlined have been onlined.
458 	 *
459 	 * The tests assume that hotplug is enabled but nobody else is using it,
460 	 * otherwise the results will be unpredictable. However, since there
461 	 * is no userspace yet in initcalls, that should be fine, as long as
462 	 * no torture test is running at the same time (see Kconfig).
463 	 */
464 	nb_available_cpus = num_online_cpus();
465 
466 	/* Check PSCI operations are set up and working. */
467 	ret = psci_ops_check();
468 	if (ret)
469 		return ret;
470 
471 	pr_info("PSCI checker started using %u CPUs\n", nb_available_cpus);
472 
473 	pr_info("Starting hotplug tests\n");
474 	ret = hotplug_tests();
475 	if (ret == 0)
476 		pr_info("Hotplug tests passed OK\n");
477 	else if (ret > 0)
478 		pr_err("%d error(s) encountered in hotplug tests\n", ret);
479 	else {
480 		pr_err("Out of memory\n");
481 		return ret;
482 	}
483 
484 	pr_info("Starting suspend tests (%d cycles per state)\n",
485 		NUM_SUSPEND_CYCLE);
486 	ret = suspend_tests();
487 	if (ret == 0)
488 		pr_info("Suspend tests passed OK\n");
489 	else if (ret > 0)
490 		pr_err("%d error(s) encountered in suspend tests\n", ret);
491 	else {
492 		switch (ret) {
493 		case -ENOMEM:
494 			pr_err("Out of memory\n");
495 			break;
496 		case -ENODEV:
497 			pr_warn("Could not start suspend tests on any CPU\n");
498 			break;
499 		}
500 	}
501 
502 	pr_info("PSCI checker completed\n");
503 	return ret < 0 ? ret : 0;
504 }
505 late_initcall(psci_checker);
506