diff options
Diffstat (limited to 'drivers/base/cpu.c')
| -rw-r--r-- | drivers/base/cpu.c | 628 |
1 files changed, 628 insertions, 0 deletions
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c new file mode 100644 index 000000000..cd204be1f --- /dev/null +++ b/drivers/base/cpu.c @@ -0,0 +1,628 @@ +// 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); +} + +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 +} + +#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"); +} + +ssize_t __weak cpu_show_tsx_async_abort(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + return sprintf(buf, "Not affected\n"); +} + +ssize_t __weak cpu_show_itlb_multihit(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sprintf(buf, "Not affected\n"); +} + +ssize_t __weak cpu_show_srbds(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sprintf(buf, "Not affected\n"); +} + +ssize_t __weak cpu_show_mmio_stale_data(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sysfs_emit(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 DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL); +static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL); +static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL); +static DEVICE_ATTR(mmio_stale_data, 0444, cpu_show_mmio_stale_data, 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, + &dev_attr_tsx_async_abort.attr, + &dev_attr_itlb_multihit.attr, + &dev_attr_srbds.attr, + &dev_attr_mmio_stale_data.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(); +} |