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                 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
 186 static 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);
 224 out_free_cpu_groups:
 225         free_cpu_groups(nb_cpu_group, &cpu_groups);
 226 out_free_cpus:
 227         free_cpumask_var(offlined_cpus);
 228         return err;
 229 }
 230
 231 static void dummy_callback(struct timer_list *unused) {}
 232
 233 static 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
 267 out_arch_exit:
 268         arch_cpu_idle_exit();
 269
 270         return ret;
 271 }
 272
 273 static 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
 367 static 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
 438 static 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 }
 492 late_initcall(psci_checker);