/* * 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 "base.h" struct bus_type cpu_subsys = {	.name = "cpu",	.dev_name = "cpu",};EXPORT_SYMBOL_GPL(cpu_subsys); static DEFINE_PER_CPU(struct device *, cpu_sys_devices); #ifdef CONFIG_HOTPLUG_CPUstatic ssize_t show_online(struct device *dev,			   struct device_attribute *attr,			   char *buf){	struct cpu *cpu = container_of(dev, struct cpu, dev); 	return sprintf(buf, "%u\n", !!cpu_online(cpu->dev.id));} static ssize_t __ref store_online(struct device *dev,				  struct device_attribute *attr,				  const char *buf, size_t count){	struct cpu *cpu = container_of(dev, struct cpu, dev);	ssize_t ret; 	cpu_hotplug_driver_lock();	switch (buf[0]) {	case '0':		ret = cpu_down(cpu->dev.id);		if (!ret)			kobject_uevent(&dev->kobj, KOBJ_OFFLINE);		break;	case '1':		ret = cpu_up(cpu->dev.id);		if (!ret)			kobject_uevent(&dev->kobj, KOBJ_ONLINE);		break;	default:		ret = -EINVAL;	}	cpu_hotplug_driver_unlock(); 	if (ret >= 0)		ret = count;	return ret;}static DEVICE_ATTR(online, 0644, show_online, store_online); static void __cpuinit register_cpu_control(struct cpu *cpu){	device_create_file(&cpu->dev, &dev_attr_online);}void unregister_cpu(struct cpu *cpu){	int logical_cpu = cpu->dev.id; 	unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); 	device_remove_file(&cpu->dev, &dev_attr_online); 	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){	return arch_cpu_probe(buf, count);} static ssize_t cpu_release_store(struct device *dev,				 struct device_attribute *attr,				 const char *buf,				 size_t count){	return arch_cpu_release(buf, count);} 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 */ #else /* ... !CONFIG_HOTPLUG_CPU */static inline void register_cpu_control(struct cpu *cpu){}#endif /* CONFIG_HOTPLUG_CPU */ #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);#endif /* * Print cpu online, possible, present, and system maps */ struct cpu_attr {	struct device_attribute attr;	const struct cpumask *const * 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);	int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map)); 	buf[n++] = '\n';	buf[n] = '\0';	return n;} #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 = cpulist_scnprintf(buf, len, 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 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.	 */} /* * 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 __cpuinit 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;#ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE	cpu->dev.bus->uevent = arch_cpu_uevent;#endif	error = device_register(&cpu->dev);	if (!error && cpu->hotpluggable)		register_cpu_control(cpu);	if (!error)		per_cpu(cpu_sys_devices, num) = &cpu->dev;	if (!error)		register_cpu_under_node(num, cpu_to_node(num)); #ifdef CONFIG_KEXEC	if (!error)		error = device_create_file(&cpu->dev, &dev_attr_crash_notes);#endif	return error;} 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); #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBEstatic DEVICE_ATTR(modalias, 0444, arch_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,#ifdef CONFIG_ARCH_HAS_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_DEVICESstatic 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();}