/*
* 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)
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_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_stop()) {
__set_current_state(TASK_RUNNING);
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);
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_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);
