cacheinfo.c

Go to the documentation of this file.

/*
 * Processor cache information made available to userspace via sysfs;
 * intended to be compatible with x86 intel_cacheinfo implementation.
 *
 * Copyright 2008 IBM Corporation
 * Author: Nathan Lynch
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 */

#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/list.h>
#include <linux/notifier.h>
#include <linux/of.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <asm/prom.h>

#include "cacheinfo.h"

/* per-cpu object for tracking:
 * - a "cache" kobject for the top-level directory
 * - a list of "index" objects representing the cpu's local cache hierarchy
 */
struct cache_dir {
    struct kobject *kobj; /* bare (not embedded) kobject for cache
                   * directory */
    struct cache_index_dir *index; /* list of index objects */
};

/* "index" object: each cpu's cache directory has an index
 * subdirectory corresponding to a cache object associated with the
 * cpu.  This object's lifetime is managed via the embedded kobject.
 */
struct cache_index_dir {
    struct kobject kobj;
    struct cache_index_dir *next; /* next index in parent directory */
    struct cache *cache;
};

/* Template for determining which OF properties to query for a given
 * cache type */
struct cache_type_info {
    const char *name;
    const char *size_prop;

    /* Allow for both [di]-cache-line-size and
     * [di]-cache-block-size properties.  According to the PowerPC
     * Processor binding, -line-size should be provided if it
     * differs from the cache block size (that which is operated
     * on by cache instructions), so we look for -line-size first.
     * See cache_get_line_size(). */

    const char *line_size_props[2];
    const char *nr_sets_prop;
};

/* These are used to index the cache_type_info array. */
#define CACHE_TYPE_UNIFIED     0
#define CACHE_TYPE_INSTRUCTION 1
#define CACHE_TYPE_DATA        2

static const struct cache_type_info cache_type_info[] = {
    {
        /* PowerPC Processor binding says the [di]-cache-*
         * must be equal on unified caches, so just use
         * d-cache properties. */
        .name            = "Unified",
        .size_prop       = "d-cache-size",
        .line_size_props = { "d-cache-line-size",
                     "d-cache-block-size", },
        .nr_sets_prop    = "d-cache-sets",
    },
    {
        .name            = "Instruction",
        .size_prop       = "i-cache-size",
        .line_size_props = { "i-cache-line-size",
                     "i-cache-block-size", },
        .nr_sets_prop    = "i-cache-sets",
    },
    {
        .name            = "Data",
        .size_prop       = "d-cache-size",
        .line_size_props = { "d-cache-line-size",
                     "d-cache-block-size", },
        .nr_sets_prop    = "d-cache-sets",
    },
};

/* Cache object: each instance of this corresponds to a distinct cache
 * in the system.  There are separate objects for Harvard caches: one
 * each for instruction and data, and each refers to the same OF node.
 * The refcount of the OF node is elevated for the lifetime of the
 * cache object.  A cache object is released when its shared_cpu_map
 * is cleared (see cache_cpu_clear).
 *
 * A cache object is on two lists: an unsorted global list
 * (cache_list) of cache objects; and a singly-linked list
 * representing the local cache hierarchy, which is ordered by level
 * (e.g. L1d -> L1i -> L2 -> L3).
 */
struct cache {
    struct device_node *ofnode;    /* OF node for this cache, may be cpu */
    struct cpumask shared_cpu_map; /* online CPUs using this cache */
    int type;                      /* split cache disambiguation */
    int level;                     /* level not explicit in device tree */
    struct list_head list;         /* global list of cache objects */
    struct cache *next_local;      /* next cache of >= level */
};

static DEFINE_PER_CPU(struct cache_dir *, cache_dir_pcpu);

/* traversal/modification of this list occurs only at cpu hotplug time;
 * access is serialized by cpu hotplug locking
 */
static LIST_HEAD(cache_list);

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

static const char *cache_type_string(const struct cache *cache)
{
    return cache_type_info[cache->type].name;
}

static void __cpuinit cache_init(struct cache *cache, int type, int level, struct device_node *ofnode)
{
    cache->type = type;
    cache->level = level;
    cache->ofnode = of_node_get(ofnode);
    INIT_LIST_HEAD(&cache->list);
    list_add(&cache->list, &cache_list);
}

static struct cache *__cpuinit new_cache(int type, int level, struct device_node *ofnode)
{
    struct cache *cache;

    cache = kzalloc(sizeof(*cache), GFP_KERNEL);
    if (cache)
        cache_init(cache, type, level, ofnode);

    return cache;
}

static void release_cache_debugcheck(struct cache *cache)
{
    struct cache *iter;

    list_for_each_entry(iter, &cache_list, list)
        WARN_ONCE(iter->next_local == cache,
              "cache for %s(%s) refers to cache for %s(%s)\n",
              iter->ofnode->full_name,
              cache_type_string(iter),
              cache->ofnode->full_name,
              cache_type_string(cache));
}

static void release_cache(struct cache *cache)
{
    if (!cache)
        return;

    pr_debug("freeing L%d %s cache for %s\n", cache->level,
         cache_type_string(cache), cache->ofnode->full_name);

    release_cache_debugcheck(cache);
    list_del(&cache->list);
    of_node_put(cache->ofnode);
    kfree(cache);
}

static void cache_cpu_set(struct cache *cache, int cpu)
{
    struct cache *next = cache;

    while (next) {
        WARN_ONCE(cpumask_test_cpu(cpu, &next->shared_cpu_map),
              "CPU %i already accounted in %s(%s)\n",
              cpu, next->ofnode->full_name,
              cache_type_string(next));
        cpumask_set_cpu(cpu, &next->shared_cpu_map);
        next = next->next_local;
    }
}

static int cache_size(const struct cache *cache, unsigned int *ret)
{
    const char *propname;
    const u32 *cache_size;

    propname = cache_type_info[cache->type].size_prop;

    cache_size = of_get_property(cache->ofnode, propname, NULL);
    if (!cache_size)
        return -ENODEV;

    *ret = *cache_size;
    return 0;
}

static int cache_size_kb(const struct cache *cache, unsigned int *ret)
{
    unsigned int size;

    if (cache_size(cache, &size))
        return -ENODEV;

    *ret = size / 1024;
    return 0;
}

/* not cache_line_size() because that's a macro in include/linux/cache.h */
static int cache_get_line_size(const struct cache *cache, unsigned int *ret)
{
    const u32 *line_size;
    int i, lim;

    lim = ARRAY_SIZE(cache_type_info[cache->type].line_size_props);

    for (i = 0; i < lim; i++) {
        const char *propname;

        propname = cache_type_info[cache->type].line_size_props[i];
        line_size = of_get_property(cache->ofnode, propname, NULL);
        if (line_size)
            break;
    }

    if (!line_size)
        return -ENODEV;

    *ret = *line_size;
    return 0;
}

static int cache_nr_sets(const struct cache *cache, unsigned int *ret)
{
    const char *propname;
    const u32 *nr_sets;

    propname = cache_type_info[cache->type].nr_sets_prop;

    nr_sets = of_get_property(cache->ofnode, propname, NULL);
    if (!nr_sets)
        return -ENODEV;

    *ret = *nr_sets;
    return 0;
}

static int cache_associativity(const struct cache *cache, unsigned int *ret)
{
    unsigned int line_size;
    unsigned int nr_sets;
    unsigned int size;

    if (cache_nr_sets(cache, &nr_sets))
        goto err;

    /* If the cache is fully associative, there is no need to
     * check the other properties.
     */
    if (nr_sets == 1) {
        *ret = 0;
        return 0;
    }

    if (cache_get_line_size(cache, &line_size))
        goto err;
    if (cache_size(cache, &size))
        goto err;

    if (!(nr_sets > 0 && size > 0 && line_size > 0))
        goto err;

    *ret = (size / nr_sets) / line_size;
    return 0;
err:
    return -ENODEV;
}

/* helper for dealing with split caches */
static struct cache *cache_find_first_sibling(struct cache *cache)
{
    struct cache *iter;

    if (cache->type == CACHE_TYPE_UNIFIED)
        return cache;

    list_for_each_entry(iter, &cache_list, list)
        if (iter->ofnode == cache->ofnode && iter->next_local == cache)
            return iter;

    return cache;
}

/* return the first cache on a local list matching node */
static struct cache *cache_lookup_by_node(const struct device_node *node)
{
    struct cache *cache = NULL;
    struct cache *iter;

    list_for_each_entry(iter, &cache_list, list) {
        if (iter->ofnode != node)
            continue;
        cache = cache_find_first_sibling(iter);
        break;
    }

    return cache;
}

static bool cache_node_is_unified(const struct device_node *np)
{
    return of_get_property(np, "cache-unified", NULL);
}

static struct cache *__cpuinit cache_do_one_devnode_unified(struct device_node *node, int level)
{
    struct cache *cache;

    pr_debug("creating L%d ucache for %s\n", level, node->full_name);

    cache = new_cache(CACHE_TYPE_UNIFIED, level, node);

    return cache;
}

static struct cache *__cpuinit cache_do_one_devnode_split(struct device_node *node, int level)
{
    struct cache *dcache, *icache;

    pr_debug("creating L%d dcache and icache for %s\n", level,
         node->full_name);

    dcache = new_cache(CACHE_TYPE_DATA, level, node);
    icache = new_cache(CACHE_TYPE_INSTRUCTION, level, node);

    if (!dcache || !icache)
        goto err;

    dcache->next_local = icache;

    return dcache;
err:
    release_cache(dcache);
    release_cache(icache);
    return NULL;
}

static struct cache *__cpuinit cache_do_one_devnode(struct device_node *node, int level)
{
    struct cache *cache;

    if (cache_node_is_unified(node))
        cache = cache_do_one_devnode_unified(node, level);
    else
        cache = cache_do_one_devnode_split(node, level);

    return cache;
}

static struct cache *__cpuinit cache_lookup_or_instantiate(struct device_node *node, int level)
{
    struct cache *cache;

    cache = cache_lookup_by_node(node);

    WARN_ONCE(cache && cache->level != level,
          "cache level mismatch on lookup (got %d, expected %d)\n",
          cache->level, level);

    if (!cache)
        cache = cache_do_one_devnode(node, level);

    return cache;
}

static void __cpuinit link_cache_lists(struct cache *smaller, struct cache *bigger)
{
    while (smaller->next_local) {
        if (smaller->next_local == bigger)
            return; /* already linked */
        smaller = smaller->next_local;
    }

    smaller->next_local = bigger;
}

static void __cpuinit do_subsidiary_caches_debugcheck(struct cache *cache)
{
    WARN_ON_ONCE(cache->level != 1);
    WARN_ON_ONCE(strcmp(cache->ofnode->type, "cpu"));
}

static void __cpuinit do_subsidiary_caches(struct cache *cache)
{
    struct device_node *subcache_node;
    int level = cache->level;

    do_subsidiary_caches_debugcheck(cache);

    while ((subcache_node = of_find_next_cache_node(cache->ofnode))) {
        struct cache *subcache;

        level++;
        subcache = cache_lookup_or_instantiate(subcache_node, level);
        of_node_put(subcache_node);
        if (!subcache)
            break;

        link_cache_lists(cache, subcache);
        cache = subcache;
    }
}

static struct cache *__cpuinit cache_chain_instantiate(unsigned int cpu_id)
{
    struct device_node *cpu_node;
    struct cache *cpu_cache = NULL;

    pr_debug("creating cache object(s) for CPU %i\n", cpu_id);

    cpu_node = of_get_cpu_node(cpu_id, NULL);
    WARN_ONCE(!cpu_node, "no OF node found for CPU %i\n", cpu_id);
    if (!cpu_node)
        goto out;

    cpu_cache = cache_lookup_or_instantiate(cpu_node, 1);
    if (!cpu_cache)
        goto out;

    do_subsidiary_caches(cpu_cache);

    cache_cpu_set(cpu_cache, cpu_id);
out:
    of_node_put(cpu_node);

    return cpu_cache;
}

static struct cache_dir *__cpuinit cacheinfo_create_cache_dir(unsigned int cpu_id)
{
    struct cache_dir *cache_dir;
    struct device *dev;
    struct kobject *kobj = NULL;

    dev = get_cpu_device(cpu_id);
    WARN_ONCE(!dev, "no dev for CPU %i\n", cpu_id);
    if (!dev)
        goto err;

    kobj = kobject_create_and_add("cache", &dev->kobj);
    if (!kobj)
        goto err;

    cache_dir = kzalloc(sizeof(*cache_dir), GFP_KERNEL);
    if (!cache_dir)
        goto err;

    cache_dir->kobj = kobj;

    WARN_ON_ONCE(per_cpu(cache_dir_pcpu, cpu_id) != NULL);

    per_cpu(cache_dir_pcpu, cpu_id) = cache_dir;

    return cache_dir;
err:
    kobject_put(kobj);
    return NULL;
}

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

    index = kobj_to_cache_index_dir(kobj);

    pr_debug("freeing index directory for L%d %s cache\n",
         index->cache->level, cache_type_string(index->cache));

    kfree(index);
}

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

    kobj_attr = container_of(attr, struct kobj_attribute, attr);

    return kobj_attr->show(k, kobj_attr, buf);
}

static struct cache *index_kobj_to_cache(struct kobject *k)
{
    struct cache_index_dir *index;

    index = kobj_to_cache_index_dir(k);

    return index->cache;
}

static ssize_t size_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
    unsigned int size_kb;
    struct cache *cache;

    cache = index_kobj_to_cache(k);

    if (cache_size_kb(cache, &size_kb))
        return -ENODEV;

    return sprintf(buf, "%uK\n", size_kb);
}

static struct kobj_attribute cache_size_attr =
    __ATTR(size, 0444, size_show, NULL);


static ssize_t line_size_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
    unsigned int line_size;
    struct cache *cache;

    cache = index_kobj_to_cache(k);

    if (cache_get_line_size(cache, &line_size))
        return -ENODEV;

    return sprintf(buf, "%u\n", line_size);
}

static struct kobj_attribute cache_line_size_attr =
    __ATTR(coherency_line_size, 0444, line_size_show, NULL);

static ssize_t nr_sets_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
    unsigned int nr_sets;
    struct cache *cache;

    cache = index_kobj_to_cache(k);

    if (cache_nr_sets(cache, &nr_sets))
        return -ENODEV;

    return sprintf(buf, "%u\n", nr_sets);
}

static struct kobj_attribute cache_nr_sets_attr =
    __ATTR(number_of_sets, 0444, nr_sets_show, NULL);

static ssize_t associativity_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
    unsigned int associativity;
    struct cache *cache;

    cache = index_kobj_to_cache(k);

    if (cache_associativity(cache, &associativity))
        return -ENODEV;

    return sprintf(buf, "%u\n", associativity);
}

static struct kobj_attribute cache_assoc_attr =
    __ATTR(ways_of_associativity, 0444, associativity_show, NULL);

static ssize_t type_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
    struct cache *cache;

    cache = index_kobj_to_cache(k);

    return sprintf(buf, "%s\n", cache_type_string(cache));
}

static struct kobj_attribute cache_type_attr =
    __ATTR(type, 0444, type_show, NULL);

static ssize_t level_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
    struct cache_index_dir *index;
    struct cache *cache;

    index = kobj_to_cache_index_dir(k);
    cache = index->cache;

    return sprintf(buf, "%d\n", cache->level);
}

static struct kobj_attribute cache_level_attr =
    __ATTR(level, 0444, level_show, NULL);

static ssize_t shared_cpu_map_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
    struct cache_index_dir *index;
    struct cache *cache;
    int len;
    int n = 0;

    index = kobj_to_cache_index_dir(k);
    cache = index->cache;
    len = PAGE_SIZE - 2;

    if (len > 1) {
        n = cpumask_scnprintf(buf, len, &cache->shared_cpu_map);
        buf[n++] = '\n';
        buf[n] = '\0';
    }
    return n;
}

static struct kobj_attribute cache_shared_cpu_map_attr =
    __ATTR(shared_cpu_map, 0444, shared_cpu_map_show, NULL);

/* Attributes which should always be created -- the kobject/sysfs core
 * does this automatically via kobj_type->default_attrs.  This is the
 * minimum data required to uniquely identify a cache.
 */
static struct attribute *cache_index_default_attrs[] = {
    &cache_type_attr.attr,
    &cache_level_attr.attr,
    &cache_shared_cpu_map_attr.attr,
    NULL,
};

/* Attributes which should be created if the cache device node has the
 * right properties -- see cacheinfo_create_index_opt_attrs
 */
static struct kobj_attribute *cache_index_opt_attrs[] = {
    &cache_size_attr,
    &cache_line_size_attr,
    &cache_nr_sets_attr,
    &cache_assoc_attr,
};

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

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

static void __cpuinit cacheinfo_create_index_opt_attrs(struct cache_index_dir *dir)
{
    const char *cache_name;
    const char *cache_type;
    struct cache *cache;
    char *buf;
    int i;

    buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
    if (!buf)
        return;

    cache = dir->cache;
    cache_name = cache->ofnode->full_name;
    cache_type = cache_type_string(cache);

    /* We don't want to create an attribute that can't provide a
     * meaningful value.  Check the return value of each optional
     * attribute's ->show method before registering the
     * attribute.
     */
    for (i = 0; i < ARRAY_SIZE(cache_index_opt_attrs); i++) {
        struct kobj_attribute *attr;
        ssize_t rc;

        attr = cache_index_opt_attrs[i];

        rc = attr->show(&dir->kobj, attr, buf);
        if (rc <= 0) {
            pr_debug("not creating %s attribute for "
                 "%s(%s) (rc = %zd)\n",
                 attr->attr.name, cache_name,
                 cache_type, rc);
            continue;
        }
        if (sysfs_create_file(&dir->kobj, &attr->attr))
            pr_debug("could not create %s attribute for %s(%s)\n",
                 attr->attr.name, cache_name, cache_type);
    }

    kfree(buf);
}

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

    index_dir = kzalloc(sizeof(*index_dir), GFP_KERNEL);
    if (!index_dir)
        goto err;

    index_dir->cache = cache;

    rc = kobject_init_and_add(&index_dir->kobj, &cache_index_type,
                  cache_dir->kobj, "index%d", index);
    if (rc)
        goto err;

    index_dir->next = cache_dir->index;
    cache_dir->index = index_dir;

    cacheinfo_create_index_opt_attrs(index_dir);

    return;
err:
    kfree(index_dir);
}

static void __cpuinit cacheinfo_sysfs_populate(unsigned int cpu_id, struct cache *cache_list)
{
    struct cache_dir *cache_dir;
    struct cache *cache;
    int index = 0;

    cache_dir = cacheinfo_create_cache_dir(cpu_id);
    if (!cache_dir)
        return;

    cache = cache_list;
    while (cache) {
        cacheinfo_create_index_dir(cache, index, cache_dir);
        index++;
        cache = cache->next_local;
    }
}

void __cpuinit cacheinfo_cpu_online(unsigned int cpu_id)
{
    struct cache *cache;

    cache = cache_chain_instantiate(cpu_id);
    if (!cache)
        return;

    cacheinfo_sysfs_populate(cpu_id, cache);
}

#ifdef CONFIG_HOTPLUG_CPU /* functions needed for cpu offline */

static struct cache *cache_lookup_by_cpu(unsigned int cpu_id)
{
    struct device_node *cpu_node;
    struct cache *cache;

    cpu_node = of_get_cpu_node(cpu_id, NULL);
    WARN_ONCE(!cpu_node, "no OF node found for CPU %i\n", cpu_id);
    if (!cpu_node)
        return NULL;

    cache = cache_lookup_by_node(cpu_node);
    of_node_put(cpu_node);

    return cache;
}

static void remove_index_dirs(struct cache_dir *cache_dir)
{
    struct cache_index_dir *index;

    index = cache_dir->index;

    while (index) {
        struct cache_index_dir *next;

        next = index->next;
        kobject_put(&index->kobj);
        index = next;
    }
}

static void remove_cache_dir(struct cache_dir *cache_dir)
{
    remove_index_dirs(cache_dir);

    kobject_put(cache_dir->kobj);

    kfree(cache_dir);
}

static void cache_cpu_clear(struct cache *cache, int cpu)
{
    while (cache) {
        struct cache *next = cache->next_local;

        WARN_ONCE(!cpumask_test_cpu(cpu, &cache->shared_cpu_map),
              "CPU %i not accounted in %s(%s)\n",
              cpu, cache->ofnode->full_name,
              cache_type_string(cache));

        cpumask_clear_cpu(cpu, &cache->shared_cpu_map);

        /* Release the cache object if all the cpus using it
         * are offline */
        if (cpumask_empty(&cache->shared_cpu_map))
            release_cache(cache);

        cache = next;
    }
}

void cacheinfo_cpu_offline(unsigned int cpu_id)
{
    struct cache_dir *cache_dir;
    struct cache *cache;

    /* Prevent userspace from seeing inconsistent state - remove
     * the sysfs hierarchy first */
    cache_dir = per_cpu(cache_dir_pcpu, cpu_id);

    /* careful, sysfs population may have failed */
    if (cache_dir)
        remove_cache_dir(cache_dir);

    per_cpu(cache_dir_pcpu, cpu_id) = NULL;

    /* clear the CPU's bit in its cache chain, possibly freeing
     * cache objects */
    cache = cache_lookup_by_cpu(cpu_id);
    if (cache)
        cache_cpu_clear(cache, cpu_id);
}
#endif /* CONFIG_HOTPLUG_CPU */