// 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();
}