linux/arch/s390/kernel/cache.c
Srivatsa S. Bhat 6575080e67 s390, cacheinfo: Fix CPU hotplug callback registration
Subsystems that want to register CPU hotplug callbacks, as well as perform
initialization for the CPUs that are already online, often do it as shown
below:

	get_online_cpus();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	register_cpu_notifier(&foobar_cpu_notifier);

	put_online_cpus();

This is wrong, since it is prone to ABBA deadlocks involving the
cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
with CPU hotplug operations).

Instead, the correct and race-free way of performing the callback
registration is:

	cpu_notifier_register_begin();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	/* Note the use of the double underscored version of the API */
	__register_cpu_notifier(&foobar_cpu_notifier);

	cpu_notifier_register_done();

Fix the cacheinfo code in s390 by using this latter form of callback
registration.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-03-20 13:43:41 +01:00

390 lines
8.8 KiB
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_SHARED:
private = 0;
break;
case CACHE_SCOPE_PRIVATE:
private = 1;
break;
default:
return;
}
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();
cpu_notifier_register_begin();
for_each_online_cpu(cpu)
cache_add_cpu(cpu);
__hotcpu_notifier(cache_hotplug, 0);
cpu_notifier_register_done();
return 0;
}
device_initcall(cache_init);