linux-kernel - [PATCH 3.2 033/164] powerpc: Fix missing L2 cache size in /sys/devices/system/cpu

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Message-ID: <lsq.1438473757.9067534@decadent.org.uk>
Date:	Sun, 02 Aug 2015 01:02:37 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Michael Ellerman" <mpe@...erman.id.au>,
	"Dave Olson" <olson@...ulusnetworks.com>
Subject: [PATCH 3.2 033/164] powerpc: Fix missing L2 cache size in
 /sys/devices/system/cpu

3.2.70-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dave Olson <olson@...ulusnetworks.com>

commit f7e9e358362557c3aa2c1ec47490f29fe880a09e upstream.

This problem appears to have been introduced in 2.6.29 by commit
93197a36a9c1 "Rewrite sysfs processor cache info code".

This caused lscpu to error out on at least e500v2 devices, eg:

  error: cannot open /sys/devices/system/cpu/cpu0/cache/index2/size: No such file or directory

Some embedded powerpc systems use cache-size in DTS for the unified L2
cache size, not d-cache-size, so we need to allow for both DTS names.
Added a new CACHE_TYPE_UNIFIED_D cache_type_info structure to handle
this.

Fixes: 93197a36a9c1 ("powerpc: Rewrite sysfs processor cache info code")
Signed-off-by: Dave Olson <olson@...ulusnetworks.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
[bwh: Backported to 3.2:
 - Adjust context
 - Preserve __cpuinit attribute on cache_do_one_devnode_unified()]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/arch/powerpc/kernel/cacheinfo.c
+++ b/arch/powerpc/kernel/cacheinfo.c
@@ -62,12 +62,22 @@ struct cache_type_info {
 };
 
 /* 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
+#define CACHE_TYPE_UNIFIED     0 /* cache-size, cache-block-size, etc. */
+#define CACHE_TYPE_UNIFIED_D   1 /* d-cache-size, d-cache-block-size, etc */
+#define CACHE_TYPE_INSTRUCTION 2
+#define CACHE_TYPE_DATA        3
 
 static const struct cache_type_info cache_type_info[] = {
 	{
+		/* Embedded systems that use cache-size, cache-block-size,
+		 * etc. for the Unified (typically L2) cache. */
+		.name            = "Unified",
+		.size_prop       = "cache-size",
+		.line_size_props = { "cache-line-size",
+				     "cache-block-size", },
+		.nr_sets_prop    = "cache-sets",
+	},
+	{
 		/* PowerPC Processor binding says the [di]-cache-*
 		 * must be equal on unified caches, so just use
 		 * d-cache properties. */
@@ -293,7 +303,8 @@ static struct cache *cache_find_first_si
 {
 	struct cache *iter;
 
-	if (cache->type == CACHE_TYPE_UNIFIED)
+	if (cache->type == CACHE_TYPE_UNIFIED ||
+	    cache->type == CACHE_TYPE_UNIFIED_D)
 		return cache;
 
 	list_for_each_entry(iter, &cache_list, list)
@@ -324,15 +335,29 @@ static bool cache_node_is_unified(const
 	return of_get_property(np, "cache-unified", NULL);
 }
 
-static struct cache *__cpuinit cache_do_one_devnode_unified(struct device_node *node, int level)
+/*
+ * Unified caches can have two different sets of tags.  Most embedded
+ * use cache-size, etc. for the unified cache size, but open firmware systems
+ * use d-cache-size, etc.   Check on initialization for which type we have, and
+ * return the appropriate structure type.  Assume it's embedded if it isn't
+ * open firmware.  If it's yet a 3rd type, then there will be missing entries
+ * in /sys/devices/system/cpu/cpu0/cache/index2/, and this code will need
+ * to be extended further.
+ */
+static int cache_is_unified_d(const struct device_node *np)
 {
-	struct cache *cache;
+	return of_get_property(np,
+		cache_type_info[CACHE_TYPE_UNIFIED_D].size_prop, NULL) ?
+		CACHE_TYPE_UNIFIED_D : CACHE_TYPE_UNIFIED;
+}
 
+/*
+ */
+static struct cache *__cpuinit cache_do_one_devnode_unified(struct device_node *node, int level)
+{
 	pr_debug("creating L%d ucache for %s\n", level, node->full_name);
 
-	cache = new_cache(CACHE_TYPE_UNIFIED, level, node);
-
-	return cache;
+	return new_cache(cache_is_unified_d(node), level, node);
 }
 
 static struct cache *__cpuinit cache_do_one_devnode_split(struct device_node *node, int level)

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