| // 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 = sysfs_emit(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 = sysfs_emit(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) |
| { |
| return sprintf(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 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; |
| 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 = sysfs_emit(buf, "%*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) |
| { |
| 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 |
| |
| 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 = sysfs_emit(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 |
| && tick_nohz_cpu_hotpluggable(cpu); |
| } |
| 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 sysfs_emit(buf, "Not affected\n"); |
| } |
| |
| ssize_t __weak cpu_show_spectre_v1(struct device *dev, |
| struct device_attribute *attr, char *buf) |
| { |
| return sysfs_emit(buf, "Not affected\n"); |
| } |
| |
| ssize_t __weak cpu_show_spectre_v2(struct device *dev, |
| struct device_attribute *attr, char *buf) |
| { |
| return sysfs_emit(buf, "Not affected\n"); |
| } |
| |
| ssize_t __weak cpu_show_spec_store_bypass(struct device *dev, |
| struct device_attribute *attr, char *buf) |
| { |
| return sysfs_emit(buf, "Not affected\n"); |
| } |
| |
| ssize_t __weak cpu_show_l1tf(struct device *dev, |
| struct device_attribute *attr, char *buf) |
| { |
| return sysfs_emit(buf, "Not affected\n"); |
| } |
| |
| ssize_t __weak cpu_show_mds(struct device *dev, |
| struct device_attribute *attr, char *buf) |
| { |
| return sysfs_emit(buf, "Not affected\n"); |
| } |
| |
| ssize_t __weak cpu_show_tsx_async_abort(struct device *dev, |
| struct device_attribute *attr, |
| char *buf) |
| { |
| return sysfs_emit(buf, "Not affected\n"); |
| } |
| |
| ssize_t __weak cpu_show_itlb_multihit(struct device *dev, |
| struct device_attribute *attr, char *buf) |
| { |
| return sysfs_emit(buf, "Not affected\n"); |
| } |
| |
| ssize_t __weak cpu_show_srbds(struct device *dev, |
| struct device_attribute *attr, char *buf) |
| { |
| return sysfs_emit(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"); |
| } |
| |
| ssize_t __weak cpu_show_retbleed(struct device *dev, |
| struct device_attribute *attr, char *buf) |
| { |
| return sysfs_emit(buf, "Not affected\n"); |
| } |
| |
| ssize_t __weak cpu_show_gds(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); |
| /* |
| * CHROMIUM: We are only addressing RETBleed on Intel for now, so AMD |
| * CPUs are still vulnerable until they are upreved to a newer kernel |
| * that also has the AMD mitigation. |
| * The tast.security.CPUVulnerabilities tast test fails if any of these |
| * files says "vulnerable", so remove it. |
| * See go/cros-retbleed-mitigations for the full story. |
| */ |
| #if 0 |
| static DEVICE_ATTR(retbleed, 0444, cpu_show_retbleed, NULL); |
| #endif |
| static DEVICE_ATTR(gather_data_sampling, 0444, cpu_show_gds, 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, |
| #if 0 |
| &dev_attr_retbleed.attr, |
| #endif |
| &dev_attr_gather_data_sampling.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(); |
| } |