drivers/firmware/psci/psci_checker.c

   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);