// 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/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_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, "%u", nr_cpu_ids); else n += snprintf(&buf[n], len - n, "%u-%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; cpumask_var_t isolated; if (!alloc_cpumask_var(&isolated, GFP_KERNEL)) return -ENOMEM; cpumask_andnot(isolated, cpu_possible_mask, housekeeping_cpumask(HK_FLAG_DOMAIN)); n = scnprintf(buf, len, "%*pbl\n", cpumask_pr_args(isolated)); free_cpumask_var(isolated); 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) { 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 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 = -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; 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_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 } #ifdef CONFIG_GENERIC_CPU_VULNERABILITIES ssize_t __weak cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "Not affected\n"); } ssize_t __weak cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "Not affected\n"); } ssize_t __weak cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "Not affected\n"); } ssize_t __weak cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "Not affected\n"); } ssize_t __weak cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "Not affected\n"); } ssize_t __weak cpu_show_mds(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "Not affected\n"); } static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL); static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL); static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL); static DEVICE_ATTR(spec_store_bypass, 0444, cpu_show_spec_store_bypass, NULL); static DEVICE_ATTR(l1tf, 0444, cpu_show_l1tf, NULL); static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL); static struct attribute *cpu_root_vulnerabilities_attrs[] = { &dev_attr_meltdown.attr, &dev_attr_spectre_v1.attr, &dev_attr_spectre_v2.attr, &dev_attr_spec_store_bypass.attr, &dev_attr_l1tf.attr, &dev_attr_mds.attr, NULL }; static const struct attribute_group cpu_root_vulnerabilities_group = { .name = "vulnerabilities", .attrs = cpu_root_vulnerabilities_attrs, }; static void __init cpu_register_vulnerabilities(void) { if (sysfs_create_group(&cpu_subsys.dev_root->kobj, &cpu_root_vulnerabilities_group)) pr_err("Unable to register CPU vulnerabilities\n"); } #else static inline void cpu_register_vulnerabilities(void) { } #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(); cpu_register_vulnerabilities(); }