cache.c

/*
 * Extract CPU cache information and expose them via sysfs.
 *
 *    Copyright IBM Corp. 2012
 *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
 */

#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 *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 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 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 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 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);