cache.c

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/*
 * Extract CPU cache information and expose them via sysfs.
 *
 *    Copyright IBM Corp. 2012
 *    Author(s): Heiko Carstens <[email protected]>
 */

#include <linux/notifier.h>
#include <linux/seq_file.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/cpu.h>
#include <asm/facility.h>

struct cache {
    unsigned long size;
    unsigned int line_size;
    unsigned int associativity;
    unsigned int nr_sets;
    unsigned int level   : 3;
    unsigned int type    : 2;
    unsigned int private : 1;
    struct list_head list;
};

struct cache_dir {
    struct kobject *kobj;
    struct cache_index_dir *index;
};

struct cache_index_dir {
    struct kobject kobj;
    int cpu;
    struct cache *cache;
    struct cache_index_dir *next;
};

enum {
    CACHE_SCOPE_NOTEXISTS,
    CACHE_SCOPE_PRIVATE,
    CACHE_SCOPE_SHARED,
    CACHE_SCOPE_RESERVED,
};

enum {
    CACHE_TYPE_SEPARATE,
    CACHE_TYPE_DATA,
    CACHE_TYPE_INSTRUCTION,
    CACHE_TYPE_UNIFIED,
};

enum {
    EXTRACT_TOPOLOGY,
    EXTRACT_LINE_SIZE,
    EXTRACT_SIZE,
    EXTRACT_ASSOCIATIVITY,
};

enum {
    CACHE_TI_UNIFIED = 0,
    CACHE_TI_DATA = 0,
    CACHE_TI_INSTRUCTION,
};

struct cache_info {
    unsigned char       : 4;
    unsigned char scope : 2;
    unsigned char type  : 2;
};

#define CACHE_MAX_LEVEL 8

union cache_topology {
    struct cache_info ci[CACHE_MAX_LEVEL];
    unsigned long long raw;
};

static const char * const cache_type_string[] = {
    "Data",
    "Instruction",
    "Unified",
};

static struct cache_dir *cache_dir_cpu[NR_CPUS];
static LIST_HEAD(cache_list);

void show_cacheinfo(struct seq_file *m)
{
    struct cache *cache;
    int index = 0;

    list_for_each_entry(cache, &cache_list, list) {
        seq_printf(m, "cache%-11d: ", index);
        seq_printf(m, "level=%d ", cache->level);
        seq_printf(m, "type=%s ", cache_type_string[cache->type]);
        seq_printf(m, "scope=%s ", cache->private ? "Private" : "Shared");
        seq_printf(m, "size=%luK ", cache->size >> 10);
        seq_printf(m, "line_size=%u ", cache->line_size);
        seq_printf(m, "associativity=%d", cache->associativity);
        seq_puts(m, "\n");
        index++;
    }
}

static inline unsigned long ecag(int ai, int li, int ti)
{
    unsigned long cmd, val;

    cmd = ai << 4 | li << 1 | ti;
    asm volatile(".insn rsy,0xeb000000004c,%0,0,0(%1)" /* ecag */
             : "=d" (val) : "a" (cmd));
    return val;
}

static int __init cache_add(int level, int private, int type)
{
    struct cache *cache;
    int ti;

    cache = kzalloc(sizeof(*cache), GFP_KERNEL);
    if (!cache)
        return -ENOMEM;
    if (type == CACHE_TYPE_INSTRUCTION)
        ti = CACHE_TI_INSTRUCTION;
    else
        ti = CACHE_TI_UNIFIED;
    cache->size = ecag(EXTRACT_SIZE, level, ti);
    cache->line_size = ecag(EXTRACT_LINE_SIZE, level, ti);
    cache->associativity = ecag(EXTRACT_ASSOCIATIVITY, level, ti);
    cache->nr_sets = cache->size / cache->associativity;
    cache->nr_sets /= cache->line_size;
    cache->private = private;
    cache->level = level + 1;
    cache->type = type - 1;
    list_add_tail(&cache->list, &cache_list);
    return 0;
}

static void __init cache_build_info(void)
{
    struct cache *cache, *next;
    union cache_topology ct;
    int level, private, rc;

    ct.raw = ecag(EXTRACT_TOPOLOGY, 0, 0);
    for (level = 0; level < CACHE_MAX_LEVEL; level++) {
        switch (ct.ci[level].scope) {
        case CACHE_SCOPE_NOTEXISTS:
        case CACHE_SCOPE_RESERVED:
            return;
        case CACHE_SCOPE_SHARED:
            private = 0;
            break;
        case CACHE_SCOPE_PRIVATE:
            private = 1;
            break;
        }
        if (ct.ci[level].type == CACHE_TYPE_SEPARATE) {
            rc  = cache_add(level, private, CACHE_TYPE_DATA);
            rc |= cache_add(level, private, CACHE_TYPE_INSTRUCTION);
        } else {
            rc = cache_add(level, private, ct.ci[level].type);
        }
        if (rc)
            goto error;
    }
    return;
error:
    list_for_each_entry_safe(cache, next, &cache_list, list) {
        list_del(&cache->list);
        kfree(cache);
    }
}

static struct cache_dir *__cpuinit cache_create_cache_dir(int cpu)
{
    struct cache_dir *cache_dir;
    struct kobject *kobj = NULL;
    struct device *dev;

    dev = get_cpu_device(cpu);
    if (!dev)
        goto out;
    kobj = kobject_create_and_add("cache", &dev->kobj);
    if (!kobj)
        goto out;
    cache_dir = kzalloc(sizeof(*cache_dir), GFP_KERNEL);
    if (!cache_dir)
        goto out;
    cache_dir->kobj = kobj;
    cache_dir_cpu[cpu] = cache_dir;
    return cache_dir;
out:
    kobject_put(kobj);
    return NULL;
}

static struct cache_index_dir *kobj_to_cache_index_dir(struct kobject *kobj)
{
    return container_of(kobj, struct cache_index_dir, kobj);
}

static void cache_index_release(struct kobject *kobj)
{
    struct cache_index_dir *index;

    index = kobj_to_cache_index_dir(kobj);
    kfree(index);
}

static ssize_t cache_index_show(struct kobject *kobj,
                struct attribute *attr, char *buf)
{
    struct kobj_attribute *kobj_attr;

    kobj_attr = container_of(attr, struct kobj_attribute, attr);
    return kobj_attr->show(kobj, kobj_attr, buf);
}

#define DEFINE_CACHE_ATTR(_name, _format, _value)           \
static ssize_t cache_##_name##_show(struct kobject *kobj,       \
                    struct kobj_attribute *attr,    \
                    char *buf)              \
{                                   \
    struct cache_index_dir *index;                  \
                                    \
    index = kobj_to_cache_index_dir(kobj);              \
    return sprintf(buf, _format, _value);               \
}                                   \
static struct kobj_attribute cache_##_name##_attr =         \
    __ATTR(_name, 0444, cache_##_name##_show, NULL);

DEFINE_CACHE_ATTR(size, "%luK\n", index->cache->size >> 10);
DEFINE_CACHE_ATTR(coherency_line_size, "%u\n", index->cache->line_size);
DEFINE_CACHE_ATTR(number_of_sets, "%u\n", index->cache->nr_sets);
DEFINE_CACHE_ATTR(ways_of_associativity, "%u\n", index->cache->associativity);
DEFINE_CACHE_ATTR(type, "%s\n", cache_type_string[index->cache->type]);
DEFINE_CACHE_ATTR(level, "%d\n", index->cache->level);

static ssize_t shared_cpu_map_func(struct kobject *kobj, int type, char *buf)
{
    struct cache_index_dir *index;
    int len;

    index = kobj_to_cache_index_dir(kobj);
    len = type ?
        cpulist_scnprintf(buf, PAGE_SIZE - 2, cpumask_of(index->cpu)) :
        cpumask_scnprintf(buf, PAGE_SIZE - 2, cpumask_of(index->cpu));
    len += sprintf(&buf[len], "\n");
    return len;
}

static ssize_t shared_cpu_map_show(struct kobject *kobj,
                   struct kobj_attribute *attr, char *buf)
{
    return shared_cpu_map_func(kobj, 0, buf);
}
static struct kobj_attribute cache_shared_cpu_map_attr =
    __ATTR(shared_cpu_map, 0444, shared_cpu_map_show, NULL);

static ssize_t shared_cpu_list_show(struct kobject *kobj,
                    struct kobj_attribute *attr, char *buf)
{
    return shared_cpu_map_func(kobj, 1, buf);
}
static struct kobj_attribute cache_shared_cpu_list_attr =
    __ATTR(shared_cpu_list, 0444, shared_cpu_list_show, NULL);

static struct attribute *cache_index_default_attrs[] = {
    &cache_type_attr.attr,
    &cache_size_attr.attr,
    &cache_number_of_sets_attr.attr,
    &cache_ways_of_associativity_attr.attr,
    &cache_level_attr.attr,
    &cache_coherency_line_size_attr.attr,
    &cache_shared_cpu_map_attr.attr,
    &cache_shared_cpu_list_attr.attr,
    NULL,
};

static const struct sysfs_ops cache_index_ops = {
    .show = cache_index_show,
};

static struct kobj_type cache_index_type = {
    .sysfs_ops = &cache_index_ops,
    .release = cache_index_release,
    .default_attrs = cache_index_default_attrs,
};

static int __cpuinit cache_create_index_dir(struct cache_dir *cache_dir,
                        struct cache *cache, int index,
                        int cpu)
{
    struct cache_index_dir *index_dir;
    int rc;

    index_dir = kzalloc(sizeof(*index_dir), GFP_KERNEL);
    if (!index_dir)
        return -ENOMEM;
    index_dir->cache = cache;
    index_dir->cpu = cpu;
    rc = kobject_init_and_add(&index_dir->kobj, &cache_index_type,
                  cache_dir->kobj, "index%d", index);
    if (rc)
        goto out;
    index_dir->next = cache_dir->index;
    cache_dir->index = index_dir;
    return 0;
out:
    kfree(index_dir);
    return rc;
}

static int __cpuinit cache_add_cpu(int cpu)
{
    struct cache_dir *cache_dir;
    struct cache *cache;
    int rc, index = 0;

    if (list_empty(&cache_list))
        return 0;
    cache_dir = cache_create_cache_dir(cpu);
    if (!cache_dir)
        return -ENOMEM;
    list_for_each_entry(cache, &cache_list, list) {
        if (!cache->private)
            break;
        rc = cache_create_index_dir(cache_dir, cache, index, cpu);
        if (rc)
            return rc;
        index++;
    }
    return 0;
}

static void __cpuinit cache_remove_cpu(int cpu)
{
    struct cache_index_dir *index, *next;
    struct cache_dir *cache_dir;

    cache_dir = cache_dir_cpu[cpu];
    if (!cache_dir)
        return;
    index = cache_dir->index;
    while (index) {
        next = index->next;
        kobject_put(&index->kobj);
        index = next;
    }
    kobject_put(cache_dir->kobj);
    kfree(cache_dir);
    cache_dir_cpu[cpu] = NULL;
}

static int __cpuinit cache_hotplug(struct notifier_block *nfb,
                   unsigned long action, void *hcpu)
{
    int cpu = (long)hcpu;
    int rc = 0;

    switch (action & ~CPU_TASKS_FROZEN) {
    case CPU_ONLINE:
        rc = cache_add_cpu(cpu);
        if (rc)
            cache_remove_cpu(cpu);
        break;
    case CPU_DEAD:
        cache_remove_cpu(cpu);
        break;
    }
    return rc ? NOTIFY_BAD : NOTIFY_OK;
}

static int __init cache_init(void)
{
    int cpu;

    if (!test_facility(34))
        return 0;
    cache_build_info();
    for_each_online_cpu(cpu)
        cache_add_cpu(cpu);
    hotcpu_notifier(cache_hotplug, 0);
    return 0;
}
device_initcall(cache_init);