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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 <linux/module.h>
24#include <linux/preempt.h>
25#include <linux/psci.h>
26#include <linux/slab.h>
27#include <linux/tick.h>
28#include <linux/topology.h>
29
30#include <asm/cpuidle.h>
31
32#include <uapi/linux/psci.h>
33
34#define NUM_SUSPEND_CYCLE (10)
35
36static unsigned int nb_available_cpus;
37static int tos_resident_cpu = -1;
38
39static atomic_t nb_active_threads;
40static struct completion suspend_threads_started =
41 COMPLETION_INITIALIZER(suspend_threads_started);
42static struct completion suspend_threads_done =
43 COMPLETION_INITIALIZER(suspend_threads_done);
44
45/*
46 * We assume that PSCI operations are used if they are available. This is not
47 * necessarily true on arm64, since the decision is based on the
48 * "enable-method" property of each CPU in the DT, but given that there is no
49 * arch-specific way to check this, we assume that the DT is sensible.
50 */
51static int psci_ops_check(void)
52{
53 int migrate_type = -1;
54 int cpu;
55
56 if (!(psci_ops.cpu_off && psci_ops.cpu_on && psci_ops.cpu_suspend)) {
57 pr_warn("Missing PSCI operations, aborting tests\n");
58 return -EOPNOTSUPP;
59 }
60
61 if (psci_ops.migrate_info_type)
62 migrate_type = psci_ops.migrate_info_type();
63
64 if (migrate_type == PSCI_0_2_TOS_UP_MIGRATE ||
65 migrate_type == PSCI_0_2_TOS_UP_NO_MIGRATE) {
66 /* There is a UP Trusted OS, find on which core it resides. */
67 for_each_online_cpu(cpu)
68 if (psci_tos_resident_on(cpu)) {
69 tos_resident_cpu = cpu;
70 break;
71 }
72 if (tos_resident_cpu == -1)
73 pr_warn("UP Trusted OS resides on no online CPU\n");
74 }
75
76 return 0;
77}
78
79static int find_clusters(const struct cpumask *cpus,
80 const struct cpumask **clusters)
81{
82 unsigned int nb = 0;
83 cpumask_var_t tmp;
84
85 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
86 return -ENOMEM;
87 cpumask_copy(tmp, cpus);
88
89 while (!cpumask_empty(tmp)) {
90 const struct cpumask *cluster =
91 topology_core_cpumask(cpumask_any(tmp));
92
93 clusters[nb++] = cluster;
94 cpumask_andnot(tmp, tmp, cluster);
95 }
96
97 free_cpumask_var(tmp);
98 return nb;
99}
100
101/*
102 * offlined_cpus is a temporary array but passing it as an argument avoids
103 * multiple allocations.
104 */
105static unsigned int down_and_up_cpus(const struct cpumask *cpus,
106 struct cpumask *offlined_cpus)
107{
108 int cpu;
109 int err = 0;
110
111 cpumask_clear(offlined_cpus);
112
113 /* Try to power down all CPUs in the mask. */
114 for_each_cpu(cpu, cpus) {
115 int ret = cpu_down(cpu);
116
117 /*
118 * cpu_down() checks the number of online CPUs before the TOS
119 * resident CPU.
120 */
121 if (cpumask_weight(offlined_cpus) + 1 == nb_available_cpus) {
122 if (ret != -EBUSY) {
123 pr_err("Unexpected return code %d while trying "
124 "to power down last online CPU %d\n",
125 ret, cpu);
126 ++err;
127 }
128 } else if (cpu == tos_resident_cpu) {
129 if (ret != -EPERM) {
130 pr_err("Unexpected return code %d while trying "
131 "to power down TOS resident CPU %d\n",
132 ret, cpu);
133 ++err;
134 }
135 } else if (ret != 0) {
136 pr_err("Error occurred (%d) while trying "
137 "to power down CPU %d\n", ret, cpu);
138 ++err;
139 }
140
141 if (ret == 0)
142 cpumask_set_cpu(cpu, offlined_cpus);
143 }
144
145 /* Try to power up all the CPUs that have been offlined. */
146 for_each_cpu(cpu, offlined_cpus) {
147 int ret = cpu_up(cpu);
148
149 if (ret != 0) {
150 pr_err("Error occurred (%d) while trying "
151 "to power up CPU %d\n", ret, cpu);
152 ++err;
153 } else {
154 cpumask_clear_cpu(cpu, offlined_cpus);
155 }
156 }
157
158 /*
159 * Something went bad at some point and some CPUs could not be turned
160 * back on.
161 */
162 WARN_ON(!cpumask_empty(offlined_cpus) ||
163 num_online_cpus() != nb_available_cpus);
164
165 return err;
166}
167
168static int hotplug_tests(void)
169{
170 int err;
171 cpumask_var_t offlined_cpus;
172 int i, nb_cluster;
173 const struct cpumask **clusters;
174 char *page_buf;
175
176 err = -ENOMEM;
177 if (!alloc_cpumask_var(&offlined_cpus, GFP_KERNEL))
178 return err;
179 /* We may have up to nb_available_cpus clusters. */
180 clusters = kmalloc_array(nb_available_cpus, sizeof(*clusters),
181 GFP_KERNEL);
182 if (!clusters)
183 goto out_free_cpus;
184 page_buf = (char *)__get_free_page(GFP_KERNEL);
185 if (!page_buf)
186 goto out_free_clusters;
187
188 err = 0;
189 nb_cluster = find_clusters(cpu_online_mask, clusters);
190
191 /*
192 * Of course the last CPU cannot be powered down and cpu_down() should
193 * refuse doing that.
194 */
195 pr_info("Trying to turn off and on again all CPUs\n");
196 err += down_and_up_cpus(cpu_online_mask, offlined_cpus);
197
198 /*
199 * Take down CPUs by cluster this time. When the last CPU is turned
200 * off, the cluster itself should shut down.
201 */
202 for (i = 0; i < nb_cluster; ++i) {
203 int cluster_id =
204 topology_physical_package_id(cpumask_any(clusters[i]));
205 ssize_t len = cpumap_print_to_pagebuf(true, page_buf,
206 clusters[i]);
207 /* Remove trailing newline. */
208 page_buf[len - 1] = '\0';
209 pr_info("Trying to turn off and on again cluster %d "
210 "(CPUs %s)\n", cluster_id, page_buf);
211 err += down_and_up_cpus(clusters[i], offlined_cpus);
212 }
213
214 free_page((unsigned long)page_buf);
215out_free_clusters:
216 kfree(clusters);
217out_free_cpus:
218 free_cpumask_var(offlined_cpus);
219 return err;
220}
221
222static void dummy_callback(unsigned long ignored) {}
223
224static int suspend_cpu(int index, bool broadcast)
225{
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 /*
251 * Replicate the common ARM cpuidle enter function
252 * (arm_enter_idle_state).
253 */
254 ret = CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, index);
255
256 if (broadcast)
257 tick_broadcast_exit();
258
259out_arch_exit:
260 arch_cpu_idle_exit();
261
262 return ret;
263}
264
265static int suspend_test_thread(void *arg)
266{
267 int cpu = (long)arg;
268 int i, nb_suspend = 0, nb_shallow_sleep = 0, nb_err = 0;
269 struct sched_param sched_priority = { .sched_priority = MAX_RT_PRIO-1 };
270 struct cpuidle_device *dev;
271 struct cpuidle_driver *drv;
272 /* No need for an actual callback, we just want to wake up the CPU. */
273 struct timer_list wakeup_timer;
274
275 /* Wait for the main thread to give the start signal. */
276 wait_for_completion(&suspend_threads_started);
277
278 /* Set maximum priority to preempt all other threads on this CPU. */
279 if (sched_setscheduler_nocheck(current, SCHED_FIFO, &sched_priority))
280 pr_warn("Failed to set suspend thread scheduler on CPU %d\n",
281 cpu);
282
283 dev = this_cpu_read(cpuidle_devices);
284 drv = cpuidle_get_cpu_driver(dev);
285
286 pr_info("CPU %d entering suspend cycles, states 1 through %d\n",
287 cpu, drv->state_count - 1);
288
289 setup_timer_on_stack(&wakeup_timer, dummy_callback, 0);
290 for (i = 0; i < NUM_SUSPEND_CYCLE; ++i) {
291 int index;
292 /*
293 * Test all possible states, except 0 (which is usually WFI and
294 * doesn't use PSCI).
295 */
296 for (index = 1; index < drv->state_count; ++index) {
297 struct cpuidle_state *state = &drv->states[index];
298 bool broadcast = state->flags & CPUIDLE_FLAG_TIMER_STOP;
299 int ret;
300
301 /*
302 * Set the timer to wake this CPU up in some time (which
303 * should be largely sufficient for entering suspend).
304 * If the local tick is disabled when entering suspend,
305 * suspend_cpu() takes care of switching to a broadcast
306 * tick, so the timer will still wake us up.
307 */
308 mod_timer(&wakeup_timer, jiffies +
309 usecs_to_jiffies(state->target_residency));
310
311 /* IRQs must be disabled during suspend operations. */
312 local_irq_disable();
313
314 ret = suspend_cpu(index, broadcast);
315
316 /*
317 * We have woken up. Re-enable IRQs to handle any
318 * pending interrupt, do not wait until the end of the
319 * loop.
320 */
321 local_irq_enable();
322
323 if (ret == index) {
324 ++nb_suspend;
325 } else if (ret >= 0) {
326 /* We did not enter the expected state. */
327 ++nb_shallow_sleep;
328 } else {
329 pr_err("Failed to suspend CPU %d: error %d "
330 "(requested state %d, cycle %d)\n",
331 cpu, ret, index, i);
332 ++nb_err;
333 }
334 }
335 }
336
337 /*
338 * Disable the timer to make sure that the timer will not trigger
339 * later.
340 */
341 del_timer(&wakeup_timer);
342
343 if (atomic_dec_return_relaxed(&nb_active_threads) == 0)
344 complete(&suspend_threads_done);
345
346 /* Give up on RT scheduling and wait for termination. */
347 sched_priority.sched_priority = 0;
348 if (sched_setscheduler_nocheck(current, SCHED_NORMAL, &sched_priority))
349 pr_warn("Failed to set suspend thread scheduler on CPU %d\n",
350 cpu);
351 for (;;) {
352 /* Needs to be set first to avoid missing a wakeup. */
353 set_current_state(TASK_INTERRUPTIBLE);
354 if (kthread_should_stop()) {
355 __set_current_state(TASK_RUNNING);
356 break;
357 }
358 schedule();
359 }
360
361 pr_info("CPU %d suspend test results: success %d, shallow states %d, errors %d\n",
362 cpu, nb_suspend, nb_shallow_sleep, nb_err);
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_stop(threads[i]);
430 out:
431 cpuidle_resume_and_unlock();
432 kfree(threads);
433 return err;
434}
435
436static int __init psci_checker(void)
437{
438 int ret;
439
440 /*
441 * Since we're in an initcall, we assume that all the CPUs that all
442 * CPUs that can be onlined have been onlined.
443 *
444 * The tests assume that hotplug is enabled but nobody else is using it,
445 * otherwise the results will be unpredictable. However, since there
446 * is no userspace yet in initcalls, that should be fine, as long as
447 * no torture test is running at the same time (see Kconfig).
448 */
449 nb_available_cpus = num_online_cpus();
450
451 /* Check PSCI operations are set up and working. */
452 ret = psci_ops_check();
453 if (ret)
454 return ret;
455
456 pr_info("PSCI checker started using %u CPUs\n", nb_available_cpus);
457
458 pr_info("Starting hotplug tests\n");
459 ret = hotplug_tests();
460 if (ret == 0)
461 pr_info("Hotplug tests passed OK\n");
462 else if (ret > 0)
463 pr_err("%d error(s) encountered in hotplug tests\n", ret);
464 else {
465 pr_err("Out of memory\n");
466 return ret;
467 }
468
469 pr_info("Starting suspend tests (%d cycles per state)\n",
470 NUM_SUSPEND_CYCLE);
471 ret = suspend_tests();
472 if (ret == 0)
473 pr_info("Suspend tests passed OK\n");
474 else if (ret > 0)
475 pr_err("%d error(s) encountered in suspend tests\n", ret);
476 else {
477 switch (ret) {
478 case -ENOMEM:
479 pr_err("Out of memory\n");
480 break;
481 case -ENODEV:
482 pr_warn("Could not start suspend tests on any CPU\n");
483 break;
484 }
485 }
486
487 pr_info("PSCI checker completed\n");
488 return ret < 0 ? ret : 0;
489}
490late_initcall(psci_checker);