linux-hardened/drivers/base/cpu.c
Alex Shi 37efa4b41f CPU / PM: expose pm_qos_resume_latency for CPUs
The cpu-dma PM QoS constraint impacts all the cpus in the system. There
is no way to let the user to choose a PM QoS constraint per cpu.

The following patch exposes to the userspace a per cpu based sysfs file
in order to let the userspace to change the value of the PM QoS latency
constraint.

This change is inoperative in its form and the cpuidle governors have to
take into account the per cpu latency constraint in addition to the
global cpu-dma latency constraint in order to operate properly.

BTW
The pm_qos_resume_latency usage defined in
Documentation/ABI/testing/sysfs-devices-power
The /sys/devices/.../power/pm_qos_resume_latency_us attribute
contains the PM QoS resume latency limit for the given device,
which is the maximum allowed time it can take to resume the
device, after it has been suspended at run time, from a resume
request to the moment the device will be ready to process I/O,
in microseconds.  If it is equal to 0, however, this means that
the PM QoS resume latency may be arbitrary.

Signed-off-by: Alex Shi <alex.shi@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-01-30 11:05:29 +01:00

510 lines
12 KiB
C

/*
* CPU subsystem support
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/cpu.h>
#include <linux/topology.h>
#include <linux/device.h>
#include <linux/node.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/percpu.h>
#include <linux/acpi.h>
#include <linux/of.h>
#include <linux/cpufeature.h>
#include <linux/tick.h>
#include <linux/pm_qos.h>
#include "base.h"
static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
static int cpu_subsys_match(struct device *dev, struct device_driver *drv)
{
/* ACPI style match is the only one that may succeed. */
if (acpi_driver_match_device(dev, drv))
return 1;
return 0;
}
#ifdef CONFIG_HOTPLUG_CPU
static void change_cpu_under_node(struct cpu *cpu,
unsigned int from_nid, unsigned int to_nid)
{
int cpuid = cpu->dev.id;
unregister_cpu_under_node(cpuid, from_nid);
register_cpu_under_node(cpuid, to_nid);
cpu->node_id = to_nid;
}
static int cpu_subsys_online(struct device *dev)
{
struct cpu *cpu = container_of(dev, struct cpu, dev);
int cpuid = dev->id;
int from_nid, to_nid;
int ret;
from_nid = cpu_to_node(cpuid);
if (from_nid == NUMA_NO_NODE)
return -ENODEV;
ret = cpu_up(cpuid);
/*
* When hot adding memory to memoryless node and enabling a cpu
* on the node, node number of the cpu may internally change.
*/
to_nid = cpu_to_node(cpuid);
if (from_nid != to_nid)
change_cpu_under_node(cpu, from_nid, to_nid);
return ret;
}
static int cpu_subsys_offline(struct device *dev)
{
return cpu_down(dev->id);
}
void unregister_cpu(struct cpu *cpu)
{
int logical_cpu = cpu->dev.id;
unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
device_unregister(&cpu->dev);
per_cpu(cpu_sys_devices, logical_cpu) = NULL;
return;
}
#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
static ssize_t cpu_probe_store(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
ssize_t cnt;
int ret;
ret = lock_device_hotplug_sysfs();
if (ret)
return ret;
cnt = arch_cpu_probe(buf, count);
unlock_device_hotplug();
return cnt;
}
static ssize_t cpu_release_store(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
ssize_t cnt;
int ret;
ret = lock_device_hotplug_sysfs();
if (ret)
return ret;
cnt = arch_cpu_release(buf, count);
unlock_device_hotplug();
return cnt;
}
static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
#endif /* CONFIG_HOTPLUG_CPU */
struct bus_type cpu_subsys = {
.name = "cpu",
.dev_name = "cpu",
.match = cpu_subsys_match,
#ifdef CONFIG_HOTPLUG_CPU
.online = cpu_subsys_online,
.offline = cpu_subsys_offline,
#endif
};
EXPORT_SYMBOL_GPL(cpu_subsys);
#ifdef CONFIG_KEXEC
#include <linux/kexec.h>
static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct cpu *cpu = container_of(dev, struct cpu, dev);
ssize_t rc;
unsigned long long addr;
int cpunum;
cpunum = cpu->dev.id;
/*
* Might be reading other cpu's data based on which cpu read thread
* has been scheduled. But cpu data (memory) is allocated once during
* boot up and this data does not change there after. Hence this
* operation should be safe. No locking required.
*/
addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
rc = sprintf(buf, "%Lx\n", addr);
return rc;
}
static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL);
static ssize_t show_crash_notes_size(struct device *dev,
struct device_attribute *attr,
char *buf)
{
ssize_t rc;
rc = sprintf(buf, "%zu\n", sizeof(note_buf_t));
return rc;
}
static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL);
static struct attribute *crash_note_cpu_attrs[] = {
&dev_attr_crash_notes.attr,
&dev_attr_crash_notes_size.attr,
NULL
};
static struct attribute_group crash_note_cpu_attr_group = {
.attrs = crash_note_cpu_attrs,
};
#endif
static const struct attribute_group *common_cpu_attr_groups[] = {
#ifdef CONFIG_KEXEC
&crash_note_cpu_attr_group,
#endif
NULL
};
static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
#ifdef CONFIG_KEXEC
&crash_note_cpu_attr_group,
#endif
NULL
};
/*
* Print cpu online, possible, present, and system maps
*/
struct cpu_attr {
struct device_attribute attr;
const struct cpumask *const map;
};
static ssize_t show_cpus_attr(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
return cpumap_print_to_pagebuf(true, buf, ca->map);
}
#define _CPU_ATTR(name, map) \
{ __ATTR(name, 0444, show_cpus_attr, NULL), map }
/* Keep in sync with cpu_subsys_attrs */
static struct cpu_attr cpu_attrs[] = {
_CPU_ATTR(online, &__cpu_online_mask),
_CPU_ATTR(possible, &__cpu_possible_mask),
_CPU_ATTR(present, &__cpu_present_mask),
};
/*
* Print values for NR_CPUS and offlined cpus
*/
static ssize_t print_cpus_kernel_max(struct device *dev,
struct device_attribute *attr, char *buf)
{
int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
return n;
}
static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
/* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
unsigned int total_cpus;
static ssize_t print_cpus_offline(struct device *dev,
struct device_attribute *attr, char *buf)
{
int n = 0, len = PAGE_SIZE-2;
cpumask_var_t offline;
/* display offline cpus < nr_cpu_ids */
if (!alloc_cpumask_var(&offline, GFP_KERNEL))
return -ENOMEM;
cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
n = scnprintf(buf, len, "%*pbl", cpumask_pr_args(offline));
free_cpumask_var(offline);
/* display offline cpus >= nr_cpu_ids */
if (total_cpus && nr_cpu_ids < total_cpus) {
if (n && n < len)
buf[n++] = ',';
if (nr_cpu_ids == total_cpus-1)
n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
else
n += snprintf(&buf[n], len - n, "%d-%d",
nr_cpu_ids, total_cpus-1);
}
n += snprintf(&buf[n], len - n, "\n");
return n;
}
static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
static ssize_t print_cpus_isolated(struct device *dev,
struct device_attribute *attr, char *buf)
{
int n = 0, len = PAGE_SIZE-2;
n = scnprintf(buf, len, "%*pbl\n", cpumask_pr_args(cpu_isolated_map));
return n;
}
static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL);
#ifdef CONFIG_NO_HZ_FULL
static ssize_t print_cpus_nohz_full(struct device *dev,
struct device_attribute *attr, char *buf)
{
int n = 0, len = PAGE_SIZE-2;
n = scnprintf(buf, len, "%*pbl\n", cpumask_pr_args(tick_nohz_full_mask));
return n;
}
static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL);
#endif
static void cpu_device_release(struct device *dev)
{
/*
* This is an empty function to prevent the driver core from spitting a
* warning at us. Yes, I know this is directly opposite of what the
* documentation for the driver core and kobjects say, and the author
* of this code has already been publically ridiculed for doing
* something as foolish as this. However, at this point in time, it is
* the only way to handle the issue of statically allocated cpu
* devices. The different architectures will have their cpu device
* code reworked to properly handle this in the near future, so this
* function will then be changed to correctly free up the memory held
* by the cpu device.
*
* Never copy this way of doing things, or you too will be made fun of
* on the linux-kernel list, you have been warned.
*/
}
#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
static ssize_t print_cpu_modalias(struct device *dev,
struct device_attribute *attr,
char *buf)
{
ssize_t n;
u32 i;
n = sprintf(buf, "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",
CPU_FEATURE_TYPEVAL);
for (i = 0; i < MAX_CPU_FEATURES; i++)
if (cpu_have_feature(i)) {
if (PAGE_SIZE < n + sizeof(",XXXX\n")) {
WARN(1, "CPU features overflow page\n");
break;
}
n += sprintf(&buf[n], ",%04X", i);
}
buf[n++] = '\n';
return n;
}
static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
{
char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
if (buf) {
print_cpu_modalias(NULL, NULL, buf);
add_uevent_var(env, "MODALIAS=%s", buf);
kfree(buf);
}
return 0;
}
#endif
/*
* register_cpu - Setup a sysfs device for a CPU.
* @cpu - cpu->hotpluggable field set to 1 will generate a control file in
* sysfs for this CPU.
* @num - CPU number to use when creating the device.
*
* Initialize and register the CPU device.
*/
int register_cpu(struct cpu *cpu, int num)
{
int error;
cpu->node_id = cpu_to_node(num);
memset(&cpu->dev, 0x00, sizeof(struct device));
cpu->dev.id = num;
cpu->dev.bus = &cpu_subsys;
cpu->dev.release = cpu_device_release;
cpu->dev.offline_disabled = !cpu->hotpluggable;
cpu->dev.offline = !cpu_online(num);
cpu->dev.of_node = of_get_cpu_node(num, NULL);
#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
cpu->dev.bus->uevent = cpu_uevent;
#endif
cpu->dev.groups = common_cpu_attr_groups;
if (cpu->hotpluggable)
cpu->dev.groups = hotplugable_cpu_attr_groups;
error = device_register(&cpu->dev);
if (error)
return error;
per_cpu(cpu_sys_devices, num) = &cpu->dev;
register_cpu_under_node(num, cpu_to_node(num));
dev_pm_qos_expose_latency_limit(&cpu->dev, 0);
return 0;
}
struct device *get_cpu_device(unsigned cpu)
{
if (cpu < nr_cpu_ids && cpu_possible(cpu))
return per_cpu(cpu_sys_devices, cpu);
else
return NULL;
}
EXPORT_SYMBOL_GPL(get_cpu_device);
static void device_create_release(struct device *dev)
{
kfree(dev);
}
static struct device *
__cpu_device_create(struct device *parent, void *drvdata,
const struct attribute_group **groups,
const char *fmt, va_list args)
{
struct device *dev = NULL;
int retval = -ENODEV;
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev) {
retval = -ENOMEM;
goto error;
}
device_initialize(dev);
dev->parent = parent;
dev->groups = groups;
dev->release = device_create_release;
dev_set_drvdata(dev, drvdata);
retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
if (retval)
goto error;
retval = device_add(dev);
if (retval)
goto error;
return dev;
error:
put_device(dev);
return ERR_PTR(retval);
}
struct device *cpu_device_create(struct device *parent, void *drvdata,
const struct attribute_group **groups,
const char *fmt, ...)
{
va_list vargs;
struct device *dev;
va_start(vargs, fmt);
dev = __cpu_device_create(parent, drvdata, groups, fmt, vargs);
va_end(vargs);
return dev;
}
EXPORT_SYMBOL_GPL(cpu_device_create);
#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
#endif
static struct attribute *cpu_root_attrs[] = {
#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
&dev_attr_probe.attr,
&dev_attr_release.attr,
#endif
&cpu_attrs[0].attr.attr,
&cpu_attrs[1].attr.attr,
&cpu_attrs[2].attr.attr,
&dev_attr_kernel_max.attr,
&dev_attr_offline.attr,
&dev_attr_isolated.attr,
#ifdef CONFIG_NO_HZ_FULL
&dev_attr_nohz_full.attr,
#endif
#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
&dev_attr_modalias.attr,
#endif
NULL
};
static struct attribute_group cpu_root_attr_group = {
.attrs = cpu_root_attrs,
};
static const struct attribute_group *cpu_root_attr_groups[] = {
&cpu_root_attr_group,
NULL,
};
bool cpu_is_hotpluggable(unsigned cpu)
{
struct device *dev = get_cpu_device(cpu);
return dev && container_of(dev, struct cpu, dev)->hotpluggable;
}
EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
#ifdef CONFIG_GENERIC_CPU_DEVICES
static DEFINE_PER_CPU(struct cpu, cpu_devices);
#endif
static void __init cpu_dev_register_generic(void)
{
#ifdef CONFIG_GENERIC_CPU_DEVICES
int i;
for_each_possible_cpu(i) {
if (register_cpu(&per_cpu(cpu_devices, i), i))
panic("Failed to register CPU device");
}
#endif
}
void __init cpu_dev_init(void)
{
if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
panic("Failed to register CPU subsystem");
cpu_dev_register_generic();
}