powerpc: Rewrite sysfs processor cache info code

The current code for providing processor cache information in sysfs
has the following deficiencies:
- several complex functions that are hard to understand
- implicit recursion (cache_desc_release -> kobject_put -> cache_desc_release)
- explicit recursion (create_cache_index_info)
- use of two per-cpu arrays when one would suffice
- duplication of work on systems where CPUs share cache

Also, when I looked at implementing support for a shared_cpu_map
attribute, it was pretty much impossible to handle hotplug without
checking every single online CPU's cache_desc list and fixing things
up... not that this is a hot path, but it would have introduced
O(n^2)-ish behavior during boot.  Addressing this involved rethinking
the core data structures used, which didn't lend itself to an
incremental approach.

This implementation maintains a "forest" (potentially more than one
tree) of cache objects which reflects the system's cache topology.
Cache objects are instantiated as needed as CPUs come online.  A
per-cpu array is used mainly for sysfs-related bookkeeping; the
objects in the array just point to the appropriate points in the
forest.

This maintains compatibility with the existing code and includes some
enhancements:
- Implement the shared_cpu_map attribute, which is essential for
  enabling userspace to discover the system's overall cache topology.
- Use cache-block-size properties if cache-line-size is not available.

I chose to place this implementation in a new file since it would have
roughly doubled the size of sysfs.c, which is already kind of messy.

Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 4 insertions, 296 deletions

diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index 0c64f10087b9..4a2ee08af6a7 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -18,6 +18,8 @@
 #include <asm/machdep.h>
 #include <asm/smp.h>
 
+#include "cacheinfo.h"
+
 #ifdef CONFIG_PPC64
 #include <asm/paca.h>
 #include <asm/lppaca.h>
@@ -25,8 +27,6 @@
 
 static DEFINE_PER_CPU(struct cpu, cpu_devices);
 
-static DEFINE_PER_CPU(struct kobject *, cache_toplevel);
-
 /*
  * SMT snooze delay stuff, 64-bit only for now
  */
@@ -343,283 +343,6 @@ static struct sysdev_attribute pa6t_attrs[] = {
 #endif /* HAS_PPC_PMC_PA6T */
 #endif /* HAS_PPC_PMC_CLASSIC */
 
-struct cache_desc {
-        struct kobject kobj;
-        struct cache_desc *next;
-        const char *type;       /* Instruction, Data, or Unified */
-        u32 size;               /* total cache size in KB */
-        u32 line_size;          /* in bytes */
-        u32 nr_sets;            /* number of sets */
-        u32 level;              /* e.g. 1, 2, 3... */
-        u32 associativity;      /* e.g. 8-way... 0 is fully associative */
-};
-
-DEFINE_PER_CPU(struct cache_desc *, cache_desc);
-
-static struct cache_desc *kobj_to_cache_desc(struct kobject *k)
-{
-        return container_of(k, struct cache_desc, kobj);
-}
-
-static void cache_desc_release(struct kobject *k)
-{
-        struct cache_desc *desc = kobj_to_cache_desc(k);
-
-        pr_debug("%s: releasing %s\n", __func__, kobject_name(k));
-
-        if (desc->next)
-                kobject_put(&desc->next->kobj);
-
-        kfree(kobj_to_cache_desc(k));
-}
-
-static ssize_t cache_desc_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 sysfs_ops cache_desc_sysfs_ops = {
-        .show = cache_desc_show,
-};
-
-static struct kobj_type cache_desc_type = {
-        .release = cache_desc_release,
-        .sysfs_ops = &cache_desc_sysfs_ops,
-};
-
-static ssize_t cache_size_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
-{
-        struct cache_desc *cache = kobj_to_cache_desc(k);
-
-        return sprintf(buf, "%uK\n", cache->size);
-}
-
-static struct kobj_attribute cache_size_attr =
-        __ATTR(size, 0444, cache_size_show, NULL);
-
-static ssize_t cache_line_size_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
-{
-        struct cache_desc *cache = kobj_to_cache_desc(k);
-
-        return sprintf(buf, "%u\n", cache->line_size);
-}
-
-static struct kobj_attribute cache_line_size_attr =
-        __ATTR(coherency_line_size, 0444, cache_line_size_show, NULL);
-
-static ssize_t cache_nr_sets_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
-{
-        struct cache_desc *cache = kobj_to_cache_desc(k);
-
-        return sprintf(buf, "%u\n", cache->nr_sets);
-}
-
-static struct kobj_attribute cache_nr_sets_attr =
-        __ATTR(number_of_sets, 0444, cache_nr_sets_show, NULL);
-
-static ssize_t cache_type_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
-{
-        struct cache_desc *cache = kobj_to_cache_desc(k);
-
-        return sprintf(buf, "%s\n", cache->type);
-}
-
-static struct kobj_attribute cache_type_attr =
-        __ATTR(type, 0444, cache_type_show, NULL);
-
-static ssize_t cache_level_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
-{
-        struct cache_desc *cache = kobj_to_cache_desc(k);
-
-        return sprintf(buf, "%u\n", cache->level);
-}
-
-static struct kobj_attribute cache_level_attr =
-        __ATTR(level, 0444, cache_level_show, NULL);
-
-static ssize_t cache_assoc_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
-{
-        struct cache_desc *cache = kobj_to_cache_desc(k);
-
-        return sprintf(buf, "%u\n", cache->associativity);
-}
-
-static struct kobj_attribute cache_assoc_attr =
-        __ATTR(ways_of_associativity, 0444, cache_assoc_show, NULL);
-
-struct cache_desc_info {
-        const char *type;
-        const char *size_prop;
-        const char *line_size_prop;
-        const char *nr_sets_prop;
-};
-
-/* PowerPC Processor binding says the [di]-cache-* must be equal on
- * unified caches, so just use d-cache properties. */
-static struct cache_desc_info ucache_info = {
-        .type = "Unified",
-        .size_prop = "d-cache-size",
-        .line_size_prop = "d-cache-line-size",
-        .nr_sets_prop = "d-cache-sets",
-};
-
-static struct cache_desc_info dcache_info = {
-        .type = "Data",
-        .size_prop = "d-cache-size",
-        .line_size_prop = "d-cache-line-size",
-        .nr_sets_prop = "d-cache-sets",
-};
-
-static struct cache_desc_info icache_info = {
-        .type = "Instruction",
-        .size_prop = "i-cache-size",
-        .line_size_prop = "i-cache-line-size",
-        .nr_sets_prop = "i-cache-sets",
-};
-
-static struct cache_desc * __cpuinit create_cache_desc(struct device_node *np, struct kobject *parent, int index, int level, struct cache_desc_info *info)
-{
-        const u32 *cache_line_size;
-        struct cache_desc *new;
-        const u32 *cache_size;
-        const u32 *nr_sets;
-        int rc;
-
-        new = kzalloc(sizeof(*new), GFP_KERNEL);
-        if (!new)
-                return NULL;
-
-        rc = kobject_init_and_add(&new->kobj, &cache_desc_type, parent,
-                                  "index%d", index);
-        if (rc)
-                goto err;
-
-        /* type */
-        new->type = info->type;
-        rc = sysfs_create_file(&new->kobj, &cache_type_attr.attr);
-        WARN_ON(rc);
-
-        /* level */
-        new->level = level;
-        rc = sysfs_create_file(&new->kobj, &cache_level_attr.attr);
-        WARN_ON(rc);
-
-        /* size */
-        cache_size = of_get_property(np, info->size_prop, NULL);
-        if (cache_size) {
-                new->size = *cache_size / 1024;
-                rc = sysfs_create_file(&new->kobj,
-                                       &cache_size_attr.attr);
-                WARN_ON(rc);
-        }
-
-        /* coherency_line_size */
-        cache_line_size = of_get_property(np, info->line_size_prop, NULL);
-        if (cache_line_size) {
-                new->line_size = *cache_line_size;
-                rc = sysfs_create_file(&new->kobj,
-                                       &cache_line_size_attr.attr);
-                WARN_ON(rc);
-        }
-
-        /* number_of_sets */
-        nr_sets = of_get_property(np, info->nr_sets_prop, NULL);
-        if (nr_sets) {
-                new->nr_sets = *nr_sets;
-                rc = sysfs_create_file(&new->kobj,
-                                       &cache_nr_sets_attr.attr);
-                WARN_ON(rc);
-        }
-
-        /* ways_of_associativity */
-        if (new->nr_sets == 1) {
-                /* fully associative */
-                new->associativity = 0;
-                goto create_assoc;
-        }
-
-        if (new->nr_sets && new->size && new->line_size) {
-                /* If we have values for all of these we can derive
-                 * the associativity. */
-                new->associativity =
-                        ((new->size * 1024) / new->nr_sets) / new->line_size;
-create_assoc:
-                rc = sysfs_create_file(&new->kobj,
-                                       &cache_assoc_attr.attr);
-                WARN_ON(rc);
-        }
-
-        return new;
-err:
-        kfree(new);
-        return NULL;
-}
-
-static bool cache_is_unified(struct device_node *np)
-{
-        return of_get_property(np, "cache-unified", NULL);
-}
-
-static struct cache_desc * __cpuinit create_cache_index_info(struct device_node *np, struct kobject *parent, int index, int level)
-{
-        struct device_node *next_cache;
-        struct cache_desc *new, **end;
-
-        pr_debug("%s(node = %s, index = %d)\n", __func__, np->full_name, index);
-
-        if (cache_is_unified(np)) {
-                new = create_cache_desc(np, parent, index, level,
-                                        &ucache_info);
-        } else {
-                new = create_cache_desc(np, parent, index, level,
-                                        &dcache_info);
-                if (new) {
-                        index++;
-                        new->next = create_cache_desc(np, parent, index, level,
-                                                      &icache_info);
-                }
-        }
-        if (!new)
-                return NULL;
-
-        end = &new->next;
-        while (*end)
-                end = &(*end)->next;
-
-        next_cache = of_find_next_cache_node(np);
-        if (!next_cache)
-                goto out;
-
-        *end = create_cache_index_info(next_cache, parent, ++index, ++level);
-
-        of_node_put(next_cache);
-out:
-        return new;
-}
-
-static void __cpuinit create_cache_info(struct sys_device *sysdev)
-{
-        struct kobject *cache_toplevel;
-        struct device_node *np = NULL;
-        int cpu = sysdev->id;
-
-        cache_toplevel = kobject_create_and_add("cache", &sysdev->kobj);
-        if (!cache_toplevel)
-                return;
-        per_cpu(cache_toplevel, cpu) = cache_toplevel;
-        np = of_get_cpu_node(cpu, NULL);
-        if (np != NULL) {
-                per_cpu(cache_desc, cpu) =
-                        create_cache_index_info(np, cache_toplevel, 0, 1);
-                of_node_put(np);
-        }
-        return;
-}
-
 static void __cpuinit register_cpu_online(unsigned int cpu)
 {
         struct cpu *c = &per_cpu(cpu_devices, cpu);
@@ -684,25 +407,10 @@ static void __cpuinit register_cpu_online(unsigned int cpu)
                 sysdev_create_file(s, &attr_dscr);
 #endif /* CONFIG_PPC64 */
 
-        create_cache_info(s);
+        cacheinfo_cpu_online(cpu);
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
-static void remove_cache_info(struct sys_device *sysdev)
-{
-        struct kobject *cache_toplevel;
-        struct cache_desc *cache_desc;
-        int cpu = sysdev->id;
-
-        cache_desc = per_cpu(cache_desc, cpu);
-        if (cache_desc != NULL)
-                kobject_put(&cache_desc->kobj);
-
-        cache_toplevel = per_cpu(cache_toplevel, cpu);
-        if (cache_toplevel != NULL)
-                kobject_put(cache_toplevel);
-}
-
 static void unregister_cpu_online(unsigned int cpu)
 {
         struct cpu *c = &per_cpu(cpu_devices, cpu);
@@ -769,7 +477,7 @@ static void unregister_cpu_online(unsigned int cpu)
                 sysdev_remove_file(s, &attr_dscr);
 #endif /* CONFIG_PPC64 */
 
-        remove_cache_info(s);
+        cacheinfo_cpu_offline(cpu);
 }
 #endif /* CONFIG_HOTPLUG_CPU */