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); 499