Hi Jeremy,
Please see below some suggestions.
On 12/10/17 20:48, Jeremy Linton wrote:
ACPI 6.2 adds a new table, which describes how processing units
are related to each other in tree like fashion. Caches are
also sprinkled throughout the tree and describe the properties
of the caches in relation to other caches and processing units.
Add the code to parse the cache hierarchy and report the total
number of levels of cache for a given core using
acpi_find_last_cache_level() as well as fill out the individual
cores cache information with cache_setup_acpi() once the
cpu_cacheinfo structure has been populated by the arch specific
code.
Further, report peers in the topology using setup_acpi_cpu_topology()
to report a unique ID for each processing unit at a given level
in the tree. These unique id's can then be used to match related
processing units which exist as threads, COD (clusters
on die), within a given package, etc.
Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
---
drivers/acpi/pptt.c | 485 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 485 insertions(+)
create mode 100644 drivers/acpi/pptt.c
diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
new file mode 100644
index 000000000000..c86715fed4a7
--- /dev/null
+++ b/drivers/acpi/pptt.c
@@ -0,1 +1,485 @@
+/*
+ * Copyright (C) 2017, ARM
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * This file implements parsing of Processor Properties Topology Table (PPTT)
+ * which is optionally used to describe the processor and cache topology.
+ * Due to the relative pointers used throughout the table, this doesn't
+ * leverage the existing subtable parsing in the kernel.
+ */
+#define pr_fmt(fmt) "ACPI PPTT: " fmt
+
+#include <linux/acpi.h>
+#include <linux/cacheinfo.h>
+#include <acpi/processor.h>
+
+/*
+ * Given the PPTT table, find and verify that the subtable entry
+ * is located within the table
+ */
+static struct acpi_subtable_header *fetch_pptt_subtable(
+ struct acpi_table_header *table_hdr, u32 pptt_ref)
+{
+ struct acpi_subtable_header *entry;
+
+ /* there isn't a subtable at reference 0 */
+ if (!pptt_ref)
+ return NULL;
Seeing the usage of pptt_ref to retrieve the subtable, would the
following be a more accurate check?
if (pptt_ref < sizeof(struct acpi_table_header))
return NULL;
+
+ if (pptt_ref + sizeof(struct acpi_subtable_header) > table_hdr->length)
+ return NULL;
+
+ entry = (struct acpi_subtable_header *)((u8 *)table_hdr + pptt_ref);
+
+ if (pptt_ref + entry->length > table_hdr->length)
+ return NULL;
+
+ return entry;
+}
+
+static struct acpi_pptt_processor *fetch_pptt_node(
+ struct acpi_table_header *table_hdr, u32 pptt_ref)
+{
+ return (struct acpi_pptt_processor *)fetch_pptt_subtable(table_hdr, pptt_ref);
+}
+
+static struct acpi_pptt_cache *fetch_pptt_cache(
+ struct acpi_table_header *table_hdr, u32 pptt_ref)
+{
+ return (struct acpi_pptt_cache *)fetch_pptt_subtable(table_hdr, pptt_ref);
+}
+
+static struct acpi_subtable_header *acpi_get_pptt_resource(
+ struct acpi_table_header *table_hdr,
+ struct acpi_pptt_processor *node, int resource)
+{
+ u32 ref;
+
+ if (resource >= node->number_of_priv_resources)
+ return NULL;
+
+ ref = *(u32 *)((u8 *)node + sizeof(struct acpi_pptt_processor) +
+ sizeof(u32) * resource);
+
I think this can be simplified as:
ref = *((u32 *)(node + 1) + resource);
+ return fetch_pptt_subtable(table_hdr, ref);
+}
+
+/*
+ * given a pptt resource, verify that it is a cache node, then walk
+ * down each level of caches, counting how many levels are found
+ * as well as checking the cache type (icache, dcache, unified). If a
+ * level & type match, then we set found, and continue the search.
+ * Once the entire cache branch has been walked return its max
+ * depth.
+ */
+static int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
+ int local_level,
+ struct acpi_subtable_header *res,
+ struct acpi_pptt_cache **found,
+ int level, int type)
+{
+ struct acpi_pptt_cache *cache;
+
+ if (res->type != ACPI_PPTT_TYPE_CACHE)
+ return 0;
+
+ cache = (struct acpi_pptt_cache *) res;
+ while (cache) {
+ local_level++;
+
+ if ((local_level == level) &&
+ (cache->flags & ACPI_PPTT_CACHE_TYPE_VALID) &&
+ ((cache->attributes & ACPI_PPTT_MASK_CACHE_TYPE) == type)) {
+ if (*found != NULL)
+ pr_err("Found duplicate cache level/type unable to determine uniqueness\n");
+
+ pr_debug("Found cache @ level %d\n", level);
+ *found = cache;
+ /*
+ * continue looking at this node's resource list
+ * to verify that we don't find a duplicate
+ * cache node.
+ */
+ }
+ cache = fetch_pptt_cache(table_hdr, cache->next_level_of_cache);
+ }
+ return local_level;
+}
+
+/*
+ * Given a CPU node look for cache levels that exist at this level, and then
+ * for each cache node, count how many levels exist below (logically above) it.
+ * If a level and type are specified, and we find that level/type, abort
+ * processing and return the acpi_pptt_cache structure.
+ */
+static struct acpi_pptt_cache *acpi_find_cache_level(
+ struct acpi_table_header *table_hdr,
+ struct acpi_pptt_processor *cpu_node,
+ int *starting_level, int level, int type)
+{
+ struct acpi_subtable_header *res;
+ int number_of_levels = *starting_level;
+ int resource = 0;
+ struct acpi_pptt_cache *ret = NULL;
+ int local_level;
+
+ /* walk down from the processor node */
+ while ((res = acpi_get_pptt_resource(table_hdr, cpu_node, resource))) {
+ resource++;
+
+ local_level = acpi_pptt_walk_cache(table_hdr, *starting_level,
+ res, &ret, level, type);
+ /*
+ * we are looking for the max depth. Since its potentially
+ * possible for a given node to have resources with differing
+ * depths verify that the depth we have found is the largest.
+ */
+ if (number_of_levels < local_level)
+ number_of_levels = local_level;
+ }
+ if (number_of_levels > *starting_level)
+ *starting_level = number_of_levels;
+
+ return ret;
+}
+
+/*
+ * given a processor node containing a processing unit, walk into it and count
+ * how many levels exist solely for it, and then walk up each level until we hit
+ * the root node (ignore the package level because it may be possible to have
+ * caches that exist across packages). Count the number of cache levels that
+ * exist at each level on the way up.
+ */
+static int acpi_process_node(struct acpi_table_header *table_hdr,
+ struct acpi_pptt_processor *cpu_node)
+{
+ int total_levels = 0;
+
+ do {
+ acpi_find_cache_level(table_hdr, cpu_node, &total_levels, 0, 0);
+ cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
+ } while (cpu_node);
+
+ return total_levels;
+}
+
+/* determine if the given node is a leaf node */
+static int acpi_pptt_leaf_node(struct acpi_table_header *table_hdr,
+ struct acpi_pptt_processor *node)
+{
+ struct acpi_subtable_header *entry;
+ unsigned long table_end;
+ u32 node_entry;
+ struct acpi_pptt_processor *cpu_node;
Can cpu_node be defined inside the loop? It isn't used outside.
+
+ table_end = (unsigned long)table_hdr + table_hdr->length;
+ node_entry = (u32)((u8 *)node - (u8 *)table_hdr);
+ entry = (struct acpi_subtable_header *)((u8 *)table_hdr +
+ sizeof(struct acpi_table_pptt));
+
+ while (((unsigned long)entry) + sizeof(struct acpi_subtable_header) < table_end) {
while ((unsigned long) (entry + 1) < table_end) {
+ cpu_node = (struct acpi_pptt_processor *)entry;
+ if ((entry->type == ACPI_PPTT_TYPE_PROCESSOR) &&
+ (cpu_node->parent == node_entry))
+ return 0;
+ entry = (struct acpi_subtable_header *)((u8 *)entry + entry->length);
+ }
+ return 1;
+}
+
+/*
+ * Find the subtable entry describing the provided processor
+ */
+static struct acpi_pptt_processor *acpi_find_processor_node(
+ struct acpi_table_header *table_hdr,
+ u32 acpi_cpu_id)
+{
+ struct acpi_subtable_header *entry;
+ unsigned long table_end;
+ struct acpi_pptt_processor *cpu_node;
+
+ table_end = (unsigned long)table_hdr + table_hdr->length;
+ entry = (struct acpi_subtable_header *)((u8 *)table_hdr +
+ sizeof(struct acpi_table_pptt));
Can I suggest having two inline functions for this and the above function?
static inline unsigned long acpi_get_table_end(const struct
acpi_table_header *);
static inline struct acpi_subtable_header *acpi_get_first_entry(const
struct acpi_table_header *);
(Feel free to adapt the names of course)
+
+ /* find the processor structure associated with this cpuid */
+ while (((unsigned long)entry) + sizeof(struct acpi_subtable_header) < table_end) {
Same as above -> (unsigned long) (entry + 1).
+ cpu_node = (struct acpi_pptt_processor *)entry;
+
+ if ((entry->type == ACPI_PPTT_TYPE_PROCESSOR) &&
+ acpi_pptt_leaf_node(table_hdr, cpu_node)) {
+ pr_debug("checking phy_cpu_id %d against acpi id %d\n",
+ acpi_cpu_id, cpu_node->acpi_processor_id);
+ if (acpi_cpu_id == cpu_node->acpi_processor_id) {
+ /* found the correct entry */
+ pr_debug("match found!\n");
+ return (struct acpi_pptt_processor *)entry;
+ }
+ }
+
+ if (entry->length == 0) {
+ pr_err("Invalid zero length subtable\n");
+ break;
+ }
+ entry = (struct acpi_subtable_header *)
+ ((u8 *)entry + entry->length);
I also think it would be nicer to have an inline function for this:
static struct acpi_subtable_header *acpi_get_next_entry(const struct
acpi_subtable_header *);
+ }
+
+ return NULL;
+}
+
+/*
+ * Given a acpi_pptt_processor node, walk up until we identify the
+ * package that the node is associated with or we run out of levels
+ * to request.
+ */
+static struct acpi_pptt_processor *acpi_find_processor_package_id(
+ struct acpi_table_header *table_hdr,
+ struct acpi_pptt_processor *cpu,
+ int level)
+{
+ struct acpi_pptt_processor *prev_node;
+
+ while (cpu && level && !(cpu->flags & ACPI_PPTT_PHYSICAL_PACKAGE)) {
+ pr_debug("level %d\n", level);
+ prev_node = fetch_pptt_node(table_hdr, cpu->parent);
+ if (prev_node == NULL)
+ break;
+ cpu = prev_node;
+ level--;
+ }
+ return cpu;
+}
+
+static int acpi_parse_pptt(struct acpi_table_header *table_hdr, u32 acpi_cpu_id)
+{
+ int number_of_levels = 0;
+ struct acpi_pptt_processor *cpu;
+
+ cpu = acpi_find_processor_node(table_hdr, acpi_cpu_id);
+ if (cpu)
+ number_of_levels = acpi_process_node(table_hdr, cpu);
+
+ return number_of_levels;
+}
+
+#define ACPI_6_2_CACHE_TYPE_DATA (0x0)
+#define ACPI_6_2_CACHE_TYPE_INSTR (1<<2)
+#define ACPI_6_2_CACHE_TYPE_UNIFIED (1<<3)
+#define ACPI_6_2_CACHE_POLICY_WB (0x0)
+#define ACPI_6_2_CACHE_POLICY_WT (1<<4)
+#define ACPI_6_2_CACHE_READ_ALLOCATE (0x0)
+#define ACPI_6_2_CACHE_WRITE_ALLOCATE (0x01)
+#define ACPI_6_2_CACHE_RW_ALLOCATE (0x02)
+
+static u8 acpi_cache_type(enum cache_type type)
+{
+ switch (type) {
+ case CACHE_TYPE_DATA:
+ pr_debug("Looking for data cache\n");
+ return ACPI_6_2_CACHE_TYPE_DATA;
+ case CACHE_TYPE_INST:
+ pr_debug("Looking for instruction cache\n");
+ return ACPI_6_2_CACHE_TYPE_INSTR;
+ default:
+ pr_debug("Unknown cache type, assume unified\n");
+ case CACHE_TYPE_UNIFIED:
+ pr_debug("Looking for unified cache\n");
+ return ACPI_6_2_CACHE_TYPE_UNIFIED;
+ }
+}
+
+/* find the ACPI node describing the cache type/level for the given CPU */
+static struct acpi_pptt_cache *acpi_find_cache_node(
+ struct acpi_table_header *table_hdr, u32 acpi_cpu_id,
+ enum cache_type type, unsigned int level,
+ struct acpi_pptt_processor **node)
+{
+ int total_levels = 0;
+ struct acpi_pptt_cache *found = NULL;
+ struct acpi_pptt_processor *cpu_node;
+ u8 acpi_type = acpi_cache_type(type);
+
+ pr_debug("Looking for CPU %d's level %d cache type %d\n",
+ acpi_cpu_id, level, acpi_type);
+
+ cpu_node = acpi_find_processor_node(table_hdr, acpi_cpu_id);
+ if (!cpu_node)
+ return NULL;
+
+ do {
+ found = acpi_find_cache_level(table_hdr, cpu_node, &total_levels, level, acpi_type);
+ *node = cpu_node;
+ cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
+ } while ((cpu_node) && (!found));
Why not combine the do...while loop and the pevious check in a simple
while loop? The same condion should work as such for a while loop.
Cheers,
--
Julien Thierry
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