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 = cpu_down(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 = cpu_up(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(int index, bool broadcast) 232 { 233 int ret; 234 235 arch_cpu_idle_enter(); 236 237 if (broadcast) { 238 /* 239 * The local timer will be shut down, we need to enter tick 240 * broadcast. 241 */ 242 ret = tick_broadcast_enter(); 243 if (ret) { 244 /* 245 * In the absence of hardware broadcast mechanism, 246 * this CPU might be used to broadcast wakeups, which 247 * may be why entering tick broadcast has failed. 248 * There is little the kernel can do to work around 249 * that, so enter WFI instead (idle state 0). 250 */ 251 cpu_do_idle(); 252 ret = 0; 253 goto out_arch_exit; 254 } 255 } 256 257 /* 258 * Replicate the common ARM cpuidle enter function 259 * (arm_enter_idle_state). 260 */ 261 ret = CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, index); 262 263 if (broadcast) 264 tick_broadcast_exit(); 265 266 out_arch_exit: 267 arch_cpu_idle_exit(); 268 269 return ret; 270 } 271 272 static int suspend_test_thread(void *arg) 273 { 274 int cpu = (long)arg; 275 int i, nb_suspend = 0, nb_shallow_sleep = 0, nb_err = 0; 276 struct sched_param sched_priority = { .sched_priority = MAX_RT_PRIO-1 }; 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 if (sched_setscheduler_nocheck(current, SCHED_FIFO, &sched_priority)) 287 pr_warn("Failed to set suspend thread scheduler on CPU %d\n", 288 cpu); 289 290 dev = this_cpu_read(cpuidle_devices); 291 drv = cpuidle_get_cpu_driver(dev); 292 293 pr_info("CPU %d entering suspend cycles, states 1 through %d\n", 294 cpu, drv->state_count - 1); 295 296 timer_setup_on_stack(&wakeup_timer, dummy_callback, 0); 297 for (i = 0; i < NUM_SUSPEND_CYCLE; ++i) { 298 int index; 299 /* 300 * Test all possible states, except 0 (which is usually WFI and 301 * doesn't use PSCI). 302 */ 303 for (index = 1; index < drv->state_count; ++index) { 304 struct cpuidle_state *state = &drv->states[index]; 305 bool broadcast = state->flags & CPUIDLE_FLAG_TIMER_STOP; 306 int ret; 307 308 /* 309 * Set the timer to wake this CPU up in some time (which 310 * should be largely sufficient for entering suspend). 311 * If the local tick is disabled when entering suspend, 312 * suspend_cpu() takes care of switching to a broadcast 313 * tick, so the timer will still wake us up. 314 */ 315 mod_timer(&wakeup_timer, jiffies + 316 usecs_to_jiffies(state->target_residency)); 317 318 /* IRQs must be disabled during suspend operations. */ 319 local_irq_disable(); 320 321 ret = suspend_cpu(index, broadcast); 322 323 /* 324 * We have woken up. Re-enable IRQs to handle any 325 * pending interrupt, do not wait until the end of the 326 * loop. 327 */ 328 local_irq_enable(); 329 330 if (ret == index) { 331 ++nb_suspend; 332 } else if (ret >= 0) { 333 /* We did not enter the expected state. */ 334 ++nb_shallow_sleep; 335 } else { 336 pr_err("Failed to suspend CPU %d: error %d " 337 "(requested state %d, cycle %d)\n", 338 cpu, ret, index, i); 339 ++nb_err; 340 } 341 } 342 } 343 344 /* 345 * Disable the timer to make sure that the timer will not trigger 346 * later. 347 */ 348 del_timer(&wakeup_timer); 349 destroy_timer_on_stack(&wakeup_timer); 350 351 if (atomic_dec_return_relaxed(&nb_active_threads) == 0) 352 complete(&suspend_threads_done); 353 354 /* Give up on RT scheduling and wait for termination. */ 355 sched_priority.sched_priority = 0; 356 if (sched_setscheduler_nocheck(current, SCHED_NORMAL, &sched_priority)) 357 pr_warn("Failed to set suspend thread scheduler on CPU %d\n", 358 cpu); 359 for (;;) { 360 /* Needs to be set first to avoid missing a wakeup. */ 361 set_current_state(TASK_INTERRUPTIBLE); 362 if (kthread_should_park()) 363 break; 364 schedule(); 365 } 366 367 pr_info("CPU %d suspend test results: success %d, shallow states %d, errors %d\n", 368 cpu, nb_suspend, nb_shallow_sleep, nb_err); 369 370 kthread_parkme(); 371 372 return nb_err; 373 } 374 375 static int suspend_tests(void) 376 { 377 int i, cpu, err = 0; 378 struct task_struct **threads; 379 int nb_threads = 0; 380 381 threads = kmalloc_array(nb_available_cpus, sizeof(*threads), 382 GFP_KERNEL); 383 if (!threads) 384 return -ENOMEM; 385 386 /* 387 * Stop cpuidle to prevent the idle tasks from entering a deep sleep 388 * mode, as it might interfere with the suspend threads on other CPUs. 389 * This does not prevent the suspend threads from using cpuidle (only 390 * the idle tasks check this status). Take the idle lock so that 391 * the cpuidle driver and device look-up can be carried out safely. 392 */ 393 cpuidle_pause_and_lock(); 394 395 for_each_online_cpu(cpu) { 396 struct task_struct *thread; 397 /* Check that cpuidle is available on that CPU. */ 398 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu); 399 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); 400 401 if (!dev || !drv) { 402 pr_warn("cpuidle not available on CPU %d, ignoring\n", 403 cpu); 404 continue; 405 } 406 407 thread = kthread_create_on_cpu(suspend_test_thread, 408 (void *)(long)cpu, cpu, 409 "psci_suspend_test"); 410 if (IS_ERR(thread)) 411 pr_err("Failed to create kthread on CPU %d\n", cpu); 412 else 413 threads[nb_threads++] = thread; 414 } 415 416 if (nb_threads < 1) { 417 err = -ENODEV; 418 goto out; 419 } 420 421 atomic_set(&nb_active_threads, nb_threads); 422 423 /* 424 * Wake up the suspend threads. To avoid the main thread being preempted 425 * before all the threads have been unparked, the suspend threads will 426 * wait for the completion of suspend_threads_started. 427 */ 428 for (i = 0; i < nb_threads; ++i) 429 wake_up_process(threads[i]); 430 complete_all(&suspend_threads_started); 431 432 wait_for_completion(&suspend_threads_done); 433 434 435 /* Stop and destroy all threads, get return status. */ 436 for (i = 0; i < nb_threads; ++i) { 437 err += kthread_park(threads[i]); 438 err += kthread_stop(threads[i]); 439 } 440 out: 441 cpuidle_resume_and_unlock(); 442 kfree(threads); 443 return err; 444 } 445 446 static int __init psci_checker(void) 447 { 448 int ret; 449 450 /* 451 * Since we're in an initcall, we assume that all the CPUs that all 452 * CPUs that can be onlined have been onlined. 453 * 454 * The tests assume that hotplug is enabled but nobody else is using it, 455 * otherwise the results will be unpredictable. However, since there 456 * is no userspace yet in initcalls, that should be fine, as long as 457 * no torture test is running at the same time (see Kconfig). 458 */ 459 nb_available_cpus = num_online_cpus(); 460 461 /* Check PSCI operations are set up and working. */ 462 ret = psci_ops_check(); 463 if (ret) 464 return ret; 465 466 pr_info("PSCI checker started using %u CPUs\n", nb_available_cpus); 467 468 pr_info("Starting hotplug tests\n"); 469 ret = hotplug_tests(); 470 if (ret == 0) 471 pr_info("Hotplug tests passed OK\n"); 472 else if (ret > 0) 473 pr_err("%d error(s) encountered in hotplug tests\n", ret); 474 else { 475 pr_err("Out of memory\n"); 476 return ret; 477 } 478 479 pr_info("Starting suspend tests (%d cycles per state)\n", 480 NUM_SUSPEND_CYCLE); 481 ret = suspend_tests(); 482 if (ret == 0) 483 pr_info("Suspend tests passed OK\n"); 484 else if (ret > 0) 485 pr_err("%d error(s) encountered in suspend tests\n", ret); 486 else { 487 switch (ret) { 488 case -ENOMEM: 489 pr_err("Out of memory\n"); 490 break; 491 case -ENODEV: 492 pr_warn("Could not start suspend tests on any CPU\n"); 493 break; 494 } 495 } 496 497 pr_info("PSCI checker completed\n"); 498 return ret < 0 ? ret : 0; 499 } 500 late_initcall(psci_checker); 501