diff options
Diffstat (limited to 'drivers/firmware/psci_checker.c')
| -rw-r--r-- | drivers/firmware/psci_checker.c | 510 |
1 files changed, 510 insertions, 0 deletions
diff --git a/drivers/firmware/psci_checker.c b/drivers/firmware/psci_checker.c new file mode 100644 index 000000000..49b6a7be3 --- /dev/null +++ b/drivers/firmware/psci_checker.c @@ -0,0 +1,510 @@ +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * Copyright (C) 2016 ARM Limited + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/atomic.h> +#include <linux/completion.h> +#include <linux/cpu.h> +#include <linux/cpuidle.h> +#include <linux/cpu_pm.h> +#include <linux/kernel.h> +#include <linux/kthread.h> +#include <uapi/linux/sched/types.h> +#include <linux/module.h> +#include <linux/preempt.h> +#include <linux/psci.h> +#include <linux/slab.h> +#include <linux/tick.h> +#include <linux/topology.h> + +#include <asm/cpuidle.h> + +#include <uapi/linux/psci.h> + +#define NUM_SUSPEND_CYCLE (10) + +static unsigned int nb_available_cpus; +static int tos_resident_cpu = -1; + +static atomic_t nb_active_threads; +static struct completion suspend_threads_started = + COMPLETION_INITIALIZER(suspend_threads_started); +static struct completion suspend_threads_done = + COMPLETION_INITIALIZER(suspend_threads_done); + +/* + * We assume that PSCI operations are used if they are available. This is not + * necessarily true on arm64, since the decision is based on the + * "enable-method" property of each CPU in the DT, but given that there is no + * arch-specific way to check this, we assume that the DT is sensible. + */ +static int psci_ops_check(void) +{ + int migrate_type = -1; + int cpu; + + if (!(psci_ops.cpu_off && psci_ops.cpu_on && psci_ops.cpu_suspend)) { + pr_warn("Missing PSCI operations, aborting tests\n"); + return -EOPNOTSUPP; + } + + if (psci_ops.migrate_info_type) + migrate_type = psci_ops.migrate_info_type(); + + if (migrate_type == PSCI_0_2_TOS_UP_MIGRATE || + migrate_type == PSCI_0_2_TOS_UP_NO_MIGRATE) { + /* There is a UP Trusted OS, find on which core it resides. */ + for_each_online_cpu(cpu) + if (psci_tos_resident_on(cpu)) { + tos_resident_cpu = cpu; + break; + } + if (tos_resident_cpu == -1) + pr_warn("UP Trusted OS resides on no online CPU\n"); + } + + return 0; +} + +/* + * offlined_cpus is a temporary array but passing it as an argument avoids + * multiple allocations. + */ +static unsigned int down_and_up_cpus(const struct cpumask *cpus, + struct cpumask *offlined_cpus) +{ + int cpu; + int err = 0; + + cpumask_clear(offlined_cpus); + + /* Try to power down all CPUs in the mask. */ + for_each_cpu(cpu, cpus) { + int ret = cpu_down(cpu); + + /* + * cpu_down() checks the number of online CPUs before the TOS + * resident CPU. + */ + if (cpumask_weight(offlined_cpus) + 1 == nb_available_cpus) { + if (ret != -EBUSY) { + pr_err("Unexpected return code %d while trying " + "to power down last online CPU %d\n", + ret, cpu); + ++err; + } + } else if (cpu == tos_resident_cpu) { + if (ret != -EPERM) { + pr_err("Unexpected return code %d while trying " + "to power down TOS resident CPU %d\n", + ret, cpu); + ++err; + } + } else if (ret != 0) { + pr_err("Error occurred (%d) while trying " + "to power down CPU %d\n", ret, cpu); + ++err; + } + + if (ret == 0) + cpumask_set_cpu(cpu, offlined_cpus); + } + + /* Try to power up all the CPUs that have been offlined. */ + for_each_cpu(cpu, offlined_cpus) { + int ret = cpu_up(cpu); + + if (ret != 0) { + pr_err("Error occurred (%d) while trying " + "to power up CPU %d\n", ret, cpu); + ++err; + } else { + cpumask_clear_cpu(cpu, offlined_cpus); + } + } + + /* + * Something went bad at some point and some CPUs could not be turned + * back on. + */ + WARN_ON(!cpumask_empty(offlined_cpus) || + num_online_cpus() != nb_available_cpus); + + return err; +} + +static void free_cpu_groups(int num, cpumask_var_t **pcpu_groups) +{ + int i; + cpumask_var_t *cpu_groups = *pcpu_groups; + + for (i = 0; i < num; ++i) + free_cpumask_var(cpu_groups[i]); + kfree(cpu_groups); +} + +static int alloc_init_cpu_groups(cpumask_var_t **pcpu_groups) +{ + int num_groups = 0; + cpumask_var_t tmp, *cpu_groups; + + if (!alloc_cpumask_var(&tmp, GFP_KERNEL)) + return -ENOMEM; + + cpu_groups = kcalloc(nb_available_cpus, sizeof(*cpu_groups), + GFP_KERNEL); + if (!cpu_groups) { + free_cpumask_var(tmp); + return -ENOMEM; + } + + cpumask_copy(tmp, cpu_online_mask); + + while (!cpumask_empty(tmp)) { + const struct cpumask *cpu_group = + topology_core_cpumask(cpumask_any(tmp)); + + if (!alloc_cpumask_var(&cpu_groups[num_groups], GFP_KERNEL)) { + free_cpumask_var(tmp); + free_cpu_groups(num_groups, &cpu_groups); + return -ENOMEM; + } + cpumask_copy(cpu_groups[num_groups++], cpu_group); + cpumask_andnot(tmp, tmp, cpu_group); + } + + free_cpumask_var(tmp); + *pcpu_groups = cpu_groups; + + return num_groups; +} + +static int hotplug_tests(void) +{ + int i, nb_cpu_group, err = -ENOMEM; + cpumask_var_t offlined_cpus, *cpu_groups; + char *page_buf; + + if (!alloc_cpumask_var(&offlined_cpus, GFP_KERNEL)) + return err; + + nb_cpu_group = alloc_init_cpu_groups(&cpu_groups); + if (nb_cpu_group < 0) + goto out_free_cpus; + page_buf = (char *)__get_free_page(GFP_KERNEL); + if (!page_buf) + goto out_free_cpu_groups; + + err = 0; + /* + * Of course the last CPU cannot be powered down and cpu_down() should + * refuse doing that. + */ + pr_info("Trying to turn off and on again all CPUs\n"); + err += down_and_up_cpus(cpu_online_mask, offlined_cpus); + + /* + * Take down CPUs by cpu group this time. When the last CPU is turned + * off, the cpu group itself should shut down. + */ + for (i = 0; i < nb_cpu_group; ++i) { + ssize_t len = cpumap_print_to_pagebuf(true, page_buf, + cpu_groups[i]); + /* Remove trailing newline. */ + page_buf[len - 1] = '\0'; + pr_info("Trying to turn off and on again group %d (CPUs %s)\n", + i, page_buf); + err += down_and_up_cpus(cpu_groups[i], offlined_cpus); + } + + free_page((unsigned long)page_buf); +out_free_cpu_groups: + free_cpu_groups(nb_cpu_group, &cpu_groups); +out_free_cpus: + free_cpumask_var(offlined_cpus); + return err; +} + +static void dummy_callback(struct timer_list *unused) {} + +static int suspend_cpu(int index, bool broadcast) +{ + int ret; + + arch_cpu_idle_enter(); + + if (broadcast) { + /* + * The local timer will be shut down, we need to enter tick + * broadcast. + */ + ret = tick_broadcast_enter(); + if (ret) { + /* + * In the absence of hardware broadcast mechanism, + * this CPU might be used to broadcast wakeups, which + * may be why entering tick broadcast has failed. + * There is little the kernel can do to work around + * that, so enter WFI instead (idle state 0). + */ + cpu_do_idle(); + ret = 0; + goto out_arch_exit; + } + } + + /* + * Replicate the common ARM cpuidle enter function + * (arm_enter_idle_state). + */ + ret = CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, index); + + if (broadcast) + tick_broadcast_exit(); + +out_arch_exit: + arch_cpu_idle_exit(); + + return ret; +} + +static int suspend_test_thread(void *arg) +{ + int cpu = (long)arg; + int i, nb_suspend = 0, nb_shallow_sleep = 0, nb_err = 0; + struct sched_param sched_priority = { .sched_priority = MAX_RT_PRIO-1 }; + struct cpuidle_device *dev; + struct cpuidle_driver *drv; + /* No need for an actual callback, we just want to wake up the CPU. */ + struct timer_list wakeup_timer; + + /* Wait for the main thread to give the start signal. */ + wait_for_completion(&suspend_threads_started); + + /* Set maximum priority to preempt all other threads on this CPU. */ + if (sched_setscheduler_nocheck(current, SCHED_FIFO, &sched_priority)) + pr_warn("Failed to set suspend thread scheduler on CPU %d\n", + cpu); + + dev = this_cpu_read(cpuidle_devices); + drv = cpuidle_get_cpu_driver(dev); + + pr_info("CPU %d entering suspend cycles, states 1 through %d\n", + cpu, drv->state_count - 1); + + timer_setup_on_stack(&wakeup_timer, dummy_callback, 0); + for (i = 0; i < NUM_SUSPEND_CYCLE; ++i) { + int index; + /* + * Test all possible states, except 0 (which is usually WFI and + * doesn't use PSCI). + */ + for (index = 1; index < drv->state_count; ++index) { + struct cpuidle_state *state = &drv->states[index]; + bool broadcast = state->flags & CPUIDLE_FLAG_TIMER_STOP; + int ret; + + /* + * Set the timer to wake this CPU up in some time (which + * should be largely sufficient for entering suspend). + * If the local tick is disabled when entering suspend, + * suspend_cpu() takes care of switching to a broadcast + * tick, so the timer will still wake us up. + */ + mod_timer(&wakeup_timer, jiffies + + usecs_to_jiffies(state->target_residency)); + + /* IRQs must be disabled during suspend operations. */ + local_irq_disable(); + + ret = suspend_cpu(index, broadcast); + + /* + * We have woken up. Re-enable IRQs to handle any + * pending interrupt, do not wait until the end of the + * loop. + */ + local_irq_enable(); + + if (ret == index) { + ++nb_suspend; + } else if (ret >= 0) { + /* We did not enter the expected state. */ + ++nb_shallow_sleep; + } else { + pr_err("Failed to suspend CPU %d: error %d " + "(requested state %d, cycle %d)\n", + cpu, ret, index, i); + ++nb_err; + } + } + } + + /* + * Disable the timer to make sure that the timer will not trigger + * later. + */ + del_timer(&wakeup_timer); + destroy_timer_on_stack(&wakeup_timer); + + if (atomic_dec_return_relaxed(&nb_active_threads) == 0) + complete(&suspend_threads_done); + + /* Give up on RT scheduling and wait for termination. */ + sched_priority.sched_priority = 0; + if (sched_setscheduler_nocheck(current, SCHED_NORMAL, &sched_priority)) + pr_warn("Failed to set suspend thread scheduler on CPU %d\n", + cpu); + for (;;) { + /* Needs to be set first to avoid missing a wakeup. */ + set_current_state(TASK_INTERRUPTIBLE); + if (kthread_should_park()) + break; + schedule(); + } + + pr_info("CPU %d suspend test results: success %d, shallow states %d, errors %d\n", + cpu, nb_suspend, nb_shallow_sleep, nb_err); + + kthread_parkme(); + + return nb_err; +} + +static int suspend_tests(void) +{ + int i, cpu, err = 0; + struct task_struct **threads; + int nb_threads = 0; + + threads = kmalloc_array(nb_available_cpus, sizeof(*threads), + GFP_KERNEL); + if (!threads) + return -ENOMEM; + + /* + * Stop cpuidle to prevent the idle tasks from entering a deep sleep + * mode, as it might interfere with the suspend threads on other CPUs. + * This does not prevent the suspend threads from using cpuidle (only + * the idle tasks check this status). Take the idle lock so that + * the cpuidle driver and device look-up can be carried out safely. + */ + cpuidle_pause_and_lock(); + + for_each_online_cpu(cpu) { + struct task_struct *thread; + /* Check that cpuidle is available on that CPU. */ + struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu); + struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); + + if (!dev || !drv) { + pr_warn("cpuidle not available on CPU %d, ignoring\n", + cpu); + continue; + } + + thread = kthread_create_on_cpu(suspend_test_thread, + (void *)(long)cpu, cpu, + "psci_suspend_test"); + if (IS_ERR(thread)) + pr_err("Failed to create kthread on CPU %d\n", cpu); + else + threads[nb_threads++] = thread; + } + + if (nb_threads < 1) { + err = -ENODEV; + goto out; + } + + atomic_set(&nb_active_threads, nb_threads); + + /* + * Wake up the suspend threads. To avoid the main thread being preempted + * before all the threads have been unparked, the suspend threads will + * wait for the completion of suspend_threads_started. + */ + for (i = 0; i < nb_threads; ++i) + wake_up_process(threads[i]); + complete_all(&suspend_threads_started); + + wait_for_completion(&suspend_threads_done); + + + /* Stop and destroy all threads, get return status. */ + for (i = 0; i < nb_threads; ++i) { + err += kthread_park(threads[i]); + err += kthread_stop(threads[i]); + } + out: + cpuidle_resume_and_unlock(); + kfree(threads); + return err; +} + +static int __init psci_checker(void) +{ + int ret; + + /* + * Since we're in an initcall, we assume that all the CPUs that all + * CPUs that can be onlined have been onlined. + * + * The tests assume that hotplug is enabled but nobody else is using it, + * otherwise the results will be unpredictable. However, since there + * is no userspace yet in initcalls, that should be fine, as long as + * no torture test is running at the same time (see Kconfig). + */ + nb_available_cpus = num_online_cpus(); + + /* Check PSCI operations are set up and working. */ + ret = psci_ops_check(); + if (ret) + return ret; + + pr_info("PSCI checker started using %u CPUs\n", nb_available_cpus); + + pr_info("Starting hotplug tests\n"); + ret = hotplug_tests(); + if (ret == 0) + pr_info("Hotplug tests passed OK\n"); + else if (ret > 0) + pr_err("%d error(s) encountered in hotplug tests\n", ret); + else { + pr_err("Out of memory\n"); + return ret; + } + + pr_info("Starting suspend tests (%d cycles per state)\n", + NUM_SUSPEND_CYCLE); + ret = suspend_tests(); + if (ret == 0) + pr_info("Suspend tests passed OK\n"); + else if (ret > 0) + pr_err("%d error(s) encountered in suspend tests\n", ret); + else { + switch (ret) { + case -ENOMEM: + pr_err("Out of memory\n"); + break; + case -ENODEV: + pr_warn("Could not start suspend tests on any CPU\n"); + break; + } + } + + pr_info("PSCI checker completed\n"); + return ret < 0 ? ret : 0; +} +late_initcall(psci_checker); |