drivers/firmware/psci/psci_checker.c

   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  */
  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  */
  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
 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
 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                 return -ENOMEM;
 162
 163         cpumask_copy(tmp, cpu_online_mask);
 164
 165         while (!cpumask_empty(tmp)) {
 166                 const struct cpumask *cpu_group =
 167                         topology_core_cpumask(cpumask_any(tmp));
 168
 169                 if (!alloc_cpumask_var(&cpu_groups[num_groups], GFP_KERNEL)) {
 170                         free_cpu_groups(num_groups, &cpu_groups);
 171                         return -ENOMEM;
 172                 }
 173                 cpumask_copy(cpu_groups[num_groups++], cpu_group);
 174                 cpumask_andnot(tmp, tmp, cpu_group);
 175         }
 176
 177         free_cpumask_var(tmp);
 178         *pcpu_groups = cpu_groups;
 179
 180         return num_groups;
 181 }
 182
 183 static int hotplug_tests(void)
 184 {
 185         int i, nb_cpu_group, err = -ENOMEM;
 186         cpumask_var_t offlined_cpus, *cpu_groups;
 187         char *page_buf;
 188
 189         if (!alloc_cpumask_var(&offlined_cpus, GFP_KERNEL))
 190                 return err;
 191
 192         nb_cpu_group = alloc_init_cpu_groups(&cpu_groups);
 193         if (nb_cpu_group < 0)
 194                 goto out_free_cpus;
 195         page_buf = (char *)__get_free_page(GFP_KERNEL);
 196         if (!page_buf)
 197                 goto out_free_cpu_groups;
 198
 199         err = 0;
 200         /*
 201          * Of course the last CPU cannot be powered down and cpu_down() should
 202          * refuse doing that.
 203          */
 204         pr_info("Trying to turn off and on again all CPUs\n");
 205         err += down_and_up_cpus(cpu_online_mask, offlined_cpus);
 206
 207         /*
 208          * Take down CPUs by cpu group this time. When the last CPU is turned
 209          * off, the cpu group itself should shut down.
 210          */
 211         for (i = 0; i < nb_cpu_group; ++i) {
 212                 ssize_t len = cpumap_print_to_pagebuf(true, page_buf,
 213                                                       cpu_groups[i]);
 214                 /* Remove trailing newline. */
 215                 page_buf[len - 1] = '\0';
 216                 pr_info("Trying to turn off and on again group %d (CPUs %s)\n",
 217                         i, page_buf);
 218                 err += down_and_up_cpus(cpu_groups[i], offlined_cpus);
 219         }
 220
 221         free_page((unsigned long)page_buf);
 222 out_free_cpu_groups:
 223         free_cpu_groups(nb_cpu_group, &cpu_groups);
 224 out_free_cpus:
 225         free_cpumask_var(offlined_cpus);
 226         return err;
 227 }
 228
 229 static void dummy_callback(struct timer_list *unused) {}
 230
 231 static int suspend_cpu(struct cpuidle_device *dev,
 232                        struct cpuidle_driver *drv, int index)
 233 {
 234         struct cpuidle_state *state = &drv->states[index];
 235         bool broadcast = state->flags & CPUIDLE_FLAG_TIMER_STOP;
 236         int ret;
 237
 238         arch_cpu_idle_enter();
 239
 240         if (broadcast) {
 241                 /*
 242                  * The local timer will be shut down, we need to enter tick
 243                  * broadcast.
 244                  */
 245                 ret = tick_broadcast_enter();
 246                 if (ret) {
 247                         /*
 248                          * In the absence of hardware broadcast mechanism,
 249                          * this CPU might be used to broadcast wakeups, which
 250                          * may be why entering tick broadcast has failed.
 251                          * There is little the kernel can do to work around
 252                          * that, so enter WFI instead (idle state 0).
 253                          */
 254                         cpu_do_idle();
 255                         ret = 0;
 256                         goto out_arch_exit;
 257                 }
 258         }
 259
 260         ret = state->enter(dev, drv, index);
 261
 262         if (broadcast)
 263                 tick_broadcast_exit();
 264
 265 out_arch_exit:
 266         arch_cpu_idle_exit();
 267
 268         return ret;
 269 }
 270
 271 static int suspend_test_thread(void *arg)
 272 {
 273         int cpu = (long)arg;
 274         int i, nb_suspend = 0, nb_shallow_sleep = 0, nb_err = 0;
 275         struct sched_param sched_priority = { .sched_priority = MAX_RT_PRIO-1 };
 276         struct cpuidle_device *dev;
 277         struct cpuidle_driver *drv;
 278         /* No need for an actual callback, we just want to wake up the CPU. */
 279         struct timer_list wakeup_timer;
 280
 281         /* Wait for the main thread to give the start signal. */
 282         wait_for_completion(&suspend_threads_started);
 283
 284         /* Set maximum priority to preempt all other threads on this CPU. */
 285         if (sched_setscheduler_nocheck(current, SCHED_FIFO, &sched_priority))
 286                 pr_warn("Failed to set suspend thread scheduler on CPU %d\n",
 287                         cpu);
 288
 289         dev = this_cpu_read(cpuidle_devices);
 290         drv = cpuidle_get_cpu_driver(dev);
 291
 292         pr_info("CPU %d entering suspend cycles, states 1 through %d\n",
 293                 cpu, drv->state_count - 1);
 294
 295         timer_setup_on_stack(&wakeup_timer, dummy_callback, 0);
 296         for (i = 0; i < NUM_SUSPEND_CYCLE; ++i) {
 297                 int index;
 298                 /*
 299                  * Test all possible states, except 0 (which is usually WFI and
 300                  * doesn't use PSCI).
 301                  */
 302                 for (index = 1; index < drv->state_count; ++index) {
 303                         int ret;
 304                         struct cpuidle_state *state = &drv->states[index];
 305
 306                         /*
 307                          * Set the timer to wake this CPU up in some time (which
 308                          * should be largely sufficient for entering suspend).
 309                          * If the local tick is disabled when entering suspend,
 310                          * suspend_cpu() takes care of switching to a broadcast
 311                          * tick, so the timer will still wake us up.
 312                          */
 313                         mod_timer(&wakeup_timer, jiffies +
 314                                   usecs_to_jiffies(state->target_residency));
 315
 316                         /* IRQs must be disabled during suspend operations. */
 317                         local_irq_disable();
 318
 319                         ret = suspend_cpu(dev, drv, index);
 320
 321                         /*
 322                          * We have woken up. Re-enable IRQs to handle any
 323                          * pending interrupt, do not wait until the end of the
 324                          * loop.
 325                          */
 326                         local_irq_enable();
 327
 328                         if (ret == index) {
 329                                 ++nb_suspend;
 330                         } else if (ret >= 0) {
 331                                 /* We did not enter the expected state. */
 332                                 ++nb_shallow_sleep;
 333                         } else {
 334                                 pr_err("Failed to suspend CPU %d: error %d "
 335                                        "(requested state %d, cycle %d)\n",
 336                                        cpu, ret, index, i);
 337                                 ++nb_err;
 338                         }
 339                 }
 340         }
 341
 342         /*
 343          * Disable the timer to make sure that the timer will not trigger
 344          * later.
 345          */
 346         del_timer(&wakeup_timer);
 347         destroy_timer_on_stack(&wakeup_timer);
 348
 349         if (atomic_dec_return_relaxed(&nb_active_threads) == 0)
 350                 complete(&suspend_threads_done);
 351
 352         /* Give up on RT scheduling and wait for termination. */
 353         sched_priority.sched_priority = 0;
 354         if (sched_setscheduler_nocheck(current, SCHED_NORMAL, &sched_priority))
 355                 pr_warn("Failed to set suspend thread scheduler on CPU %d\n",
 356                         cpu);
 357         for (;;) {
 358                 /* Needs to be set first to avoid missing a wakeup. */
 359                 set_current_state(TASK_INTERRUPTIBLE);
 360                 if (kthread_should_park())
 361                         break;
 362                 schedule();
 363         }
 364
 365         pr_info("CPU %d suspend test results: success %d, shallow states %d, errors %d\n",
 366                 cpu, nb_suspend, nb_shallow_sleep, nb_err);
 367
 368         kthread_parkme();
 369
 370         return nb_err;
 371 }
 372
 373 static int suspend_tests(void)
 374 {
 375         int i, cpu, err = 0;
 376         struct task_struct **threads;
 377         int nb_threads = 0;
 378
 379         threads = kmalloc_array(nb_available_cpus, sizeof(*threads),
 380                                 GFP_KERNEL);
 381         if (!threads)
 382                 return -ENOMEM;
 383
 384         /*
 385          * Stop cpuidle to prevent the idle tasks from entering a deep sleep
 386          * mode, as it might interfere with the suspend threads on other CPUs.
 387          * This does not prevent the suspend threads from using cpuidle (only
 388          * the idle tasks check this status). Take the idle lock so that
 389          * the cpuidle driver and device look-up can be carried out safely.
 390          */
 391         cpuidle_pause_and_lock();
 392
 393         for_each_online_cpu(cpu) {
 394                 struct task_struct *thread;
 395                 /* Check that cpuidle is available on that CPU. */
 396                 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
 397                 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 398
 399                 if (!dev || !drv) {
 400                         pr_warn("cpuidle not available on CPU %d, ignoring\n",
 401                                 cpu);
 402                         continue;
 403                 }
 404
 405                 thread = kthread_create_on_cpu(suspend_test_thread,
 406                                                (void *)(long)cpu, cpu,
 407                                                "psci_suspend_test");
 408                 if (IS_ERR(thread))
 409                         pr_err("Failed to create kthread on CPU %d\n", cpu);
 410                 else
 411                         threads[nb_threads++] = thread;
 412         }
 413
 414         if (nb_threads < 1) {
 415                 err = -ENODEV;
 416                 goto out;
 417         }
 418
 419         atomic_set(&nb_active_threads, nb_threads);
 420
 421         /*
 422          * Wake up the suspend threads. To avoid the main thread being preempted
 423          * before all the threads have been unparked, the suspend threads will
 424          * wait for the completion of suspend_threads_started.
 425          */
 426         for (i = 0; i < nb_threads; ++i)
 427                 wake_up_process(threads[i]);
 428         complete_all(&suspend_threads_started);
 429
 430         wait_for_completion(&suspend_threads_done);
 431
 432
 433         /* Stop and destroy all threads, get return status. */
 434         for (i = 0; i < nb_threads; ++i) {
 435                 err += kthread_park(threads[i]);
 436                 err += kthread_stop(threads[i]);
 437         }
 438  out:
 439         cpuidle_resume_and_unlock();
 440         kfree(threads);
 441         return err;
 442 }
 443
 444 static int __init psci_checker(void)
 445 {
 446         int ret;
 447
 448         /*
 449          * Since we're in an initcall, we assume that all the CPUs that all
 450          * CPUs that can be onlined have been onlined.
 451          *
 452          * The tests assume that hotplug is enabled but nobody else is using it,
 453          * otherwise the results will be unpredictable. However, since there
 454          * is no userspace yet in initcalls, that should be fine, as long as
 455          * no torture test is running at the same time (see Kconfig).
 456          */
 457         nb_available_cpus = num_online_cpus();
 458
 459         /* Check PSCI operations are set up and working. */
 460         ret = psci_ops_check();
 461         if (ret)
 462                 return ret;
 463
 464         pr_info("PSCI checker started using %u CPUs\n", nb_available_cpus);
 465
 466         pr_info("Starting hotplug tests\n");
 467         ret = hotplug_tests();
 468         if (ret == 0)
 469                 pr_info("Hotplug tests passed OK\n");
 470         else if (ret > 0)
 471                 pr_err("%d error(s) encountered in hotplug tests\n", ret);
 472         else {
 473                 pr_err("Out of memory\n");
 474                 return ret;
 475         }
 476
 477         pr_info("Starting suspend tests (%d cycles per state)\n",
 478                 NUM_SUSPEND_CYCLE);
 479         ret = suspend_tests();
 480         if (ret == 0)
 481                 pr_info("Suspend tests passed OK\n");
 482         else if (ret > 0)
 483                 pr_err("%d error(s) encountered in suspend tests\n", ret);
 484         else {
 485                 switch (ret) {
 486                 case -ENOMEM:
 487                         pr_err("Out of memory\n");
 488                         break;
 489                 case -ENODEV:
 490                         pr_warn("Could not start suspend tests on any CPU\n");
 491                         break;
 492                 }
 493         }
 494
 495         pr_info("PSCI checker completed\n");
 496         return ret < 0 ? ret : 0;
 497 }
 498 late_initcall(psci_checker);