// SPDX-License-Identifier: GPL-2.0/* * 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 <linux/delay.h>#include <linux/sched/isolation.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_CPUstatic 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;	int retries = 0; 	from_nid = cpu_to_node(cpuid);	if (from_nid == NUMA_NO_NODE)		return -ENODEV; retry:	ret = cpu_device_up(dev); 	/*	 * If -EBUSY is returned, it is likely that hotplug is temporarily	 * disabled when cpu_hotplug_disable() was called. This condition is	 * transient. So we retry after waiting for an exponentially	 * increasing delay up to a total of at least 620ms as some PCI	 * device initialization can take quite a while.	 */	if (ret == -EBUSY) {		retries++;		if (retries > 5)			return ret;		msleep(10 * (1 << retries));		goto retry;	} 	/*	 * 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_device_down(dev);} 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_RELEASEstatic 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 */ #ifdef CONFIG_CRASH_DUMP#include <linux/kexec.h> static ssize_t crash_notes_show(struct device *dev,				struct device_attribute *attr,				char *buf){	struct cpu *cpu = container_of(dev, struct cpu, dev);	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)); 	return sysfs_emit(buf, "%llx\n", addr);}static DEVICE_ATTR_ADMIN_RO(crash_notes); static ssize_t crash_notes_size_show(struct device *dev,				     struct device_attribute *attr,				     char *buf){	return sysfs_emit(buf, "%zu\n", sizeof(note_buf_t));}static DEVICE_ATTR_ADMIN_RO(crash_notes_size); static struct attribute *crash_note_cpu_attrs[] = {	&dev_attr_crash_notes.attr,	&dev_attr_crash_notes_size.attr,	NULL}; static const 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_CRASH_DUMP	&crash_note_cpu_attr_group,#endif	NULL}; static const struct attribute_group *hotplugable_cpu_attr_groups[] = {#ifdef CONFIG_CRASH_DUMP	&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){	return sysfs_emit(buf, "%d\n", NR_CPUS - 1);}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 len = 0;	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);	len += sysfs_emit_at(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) {		len += sysfs_emit_at(buf, len, ","); 		if (nr_cpu_ids == total_cpus-1)			len += sysfs_emit_at(buf, len, "%u", nr_cpu_ids);		else			len += sysfs_emit_at(buf, len, "%u-%d",					     nr_cpu_ids, total_cpus - 1);	} 	len += sysfs_emit_at(buf, len, "\n"); 	return len;}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 len;	cpumask_var_t isolated; 	if (!alloc_cpumask_var(&isolated, GFP_KERNEL))		return -ENOMEM; 	cpumask_andnot(isolated, cpu_possible_mask,		       housekeeping_cpumask(HK_TYPE_DOMAIN));	len = sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(isolated)); 	free_cpumask_var(isolated); 	return len;}static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL); #ifdef CONFIG_NO_HZ_FULLstatic ssize_t print_cpus_nohz_full(struct device *dev,				    struct device_attribute *attr, char *buf){	return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(tick_nohz_full_mask));}static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL);#endif #ifdef CONFIG_CRASH_HOTPLUGstatic ssize_t crash_hotplug_show(struct device *dev,				     struct device_attribute *attr,				     char *buf){	return sysfs_emit(buf, "%d\n", crash_check_hotplug_support());}static DEVICE_ATTR_ADMIN_RO(crash_hotplug);#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_AUTOPROBEstatic ssize_t print_cpu_modalias(struct device *dev,				  struct device_attribute *attr,				  char *buf){	int len = 0;	u32 i; 	len += sysfs_emit_at(buf, len,			     "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",			     CPU_FEATURE_TYPEVAL); 	for (i = 0; i < MAX_CPU_FEATURES; i++)		if (cpu_have_feature(i)) {			if (len + sizeof(",XXXX\n") >= PAGE_SIZE) {				WARN(1, "CPU features overflow page\n");				break;			}			len += sysfs_emit_at(buf, len, ",%04X", i);		}	len += sysfs_emit_at(buf, len, "\n");	return len;} static int cpu_uevent(const 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 const 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#ifdef CONFIG_GENERIC_CPU_AUTOPROBE	.uevent = cpu_uevent,#endif};EXPORT_SYMBOL_GPL(cpu_subsys); /* * 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);	cpu->dev.groups = common_cpu_attr_groups;	if (cpu->hotpluggable)		cpu->dev.groups = hotplugable_cpu_attr_groups;	error = device_register(&cpu->dev);	if (error) {		put_device(&cpu->dev);		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,					PM_QOS_RESUME_LATENCY_NO_CONSTRAINT); 	return 0;} struct device *get_cpu_device(unsigned int 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);} __printf(4, 0)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 = -ENOMEM; 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);	if (!dev)		goto error; 	device_initialize(dev);	dev->parent = parent;	dev->groups = groups;	dev->release = device_create_release;	device_set_pm_not_required(dev);	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_AUTOPROBEstatic 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

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