On 12/10/2017 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.
As already commented, there are many lines over 80 characters.
And so far I only really looked at cpu topology part.
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;
+
+ 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);
+
+ return fetch_pptt_subtable(table_hdr, ref);
+}
+
+/*
+ * given a pptt resource, verify that it is a cache node, then walk
/s/given/Given/
+ * 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;
please remove whitespace before 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;
+
+ 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) {
+ 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));
+
This is the first time looking at your implementation of the PPTT
driver. Has it been mentioned before that it is rather inefficient to
re-parse the table for every cpu in the system? Actually within the cpu
parsing loop we call acpi_pptt_leaf_node(), which does another table
parsing loop.
However this is simple.
I do know the version from wangxiongfeng had a kmalloc per node, which
would also be somewhat inefficient.
But I worry that this implementation does not scale with larger numbers
of CPUs.
+ /* find the processor structure associated with this cpuid */
+ while (((unsigned long)entry) + sizeof(struct acpi_subtable_header) < table_end) {
+ 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");
Do we really need to add 2 debug messages for case of checking for and
finding a valid match?
+ 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);
+ }
+
+ 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(
One would assume from the name that this function returns an integer
value, that being an index for the package for that cpu
+ struct acpi_table_header *table_hdr,
+ struct acpi_pptt_processor *cpu,
Do you think that "cpu_node" would be a better name?
+ int level)
+{
+ struct acpi_pptt_processor *prev_node;
+
+ while (cpu && level && !(cpu->flags & ACPI_PPTT_PHYSICAL_PACKAGE)) {
+ pr_debug("level %d\n", level);
that's not such a useful message and I can imagine it creates so many prints
+ 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));
+
+ return found;
+}
+
+int acpi_find_last_cache_level(unsigned int cpu)
+{
+ u32 acpi_cpu_id;
+ struct acpi_table_header *table;
+ int number_of_levels = 0;
+ acpi_status status;
+
+ pr_debug("Cache Setup find last level cpu=%d\n", cpu);
these prints (and others) probably should be verbose level or removed
+
+ acpi_cpu_id = acpi_cpu_get_madt_gicc(cpu)->uid;
+ status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
+ if (ACPI_FAILURE(status)) {
+ pr_err_once("No PPTT table found, cache topology may be inaccurate\n");
is this really an error?
+ } else {
+ number_of_levels = acpi_parse_pptt(table, acpi_cpu_id);
+ acpi_put_table(table);
+ }
+ pr_debug("Cache Setup find last level level=%d\n", number_of_levels);
I think that this could be better worded
+
+ return number_of_levels;
+}
+
+/*
+ * The ACPI spec implies that the fields in the cache structures are used to
+ * extend and correct the information probed from the hardware. In the case
+ * of arm64 the CCSIDR probing has been removed because it might be incorrect.
+ */
+static void update_cache_properties(struct cacheinfo *this_leaf,
+ struct acpi_pptt_cache *found_cache,
+ struct acpi_pptt_processor *cpu_node)
+{
+ if (found_cache->flags & ACPI_PPTT_SIZE_PROPERTY_VALID)
+ this_leaf->size = found_cache->size;
+ if (found_cache->flags & ACPI_PPTT_LINE_SIZE_VALID)
+ this_leaf->coherency_line_size = found_cache->line_size;
+ if (found_cache->flags & ACPI_PPTT_NUMBER_OF_SETS_VALID)
+ this_leaf->number_of_sets = found_cache->number_of_sets;
+ if (found_cache->flags & ACPI_PPTT_ASSOCIATIVITY_VALID)
+ this_leaf->ways_of_associativity = found_cache->associativity;
+ if (found_cache->flags & ACPI_PPTT_WRITE_POLICY_VALID)
+ switch (found_cache->attributes & ACPI_PPTT_MASK_WRITE_POLICY) {
+ case ACPI_6_2_CACHE_POLICY_WT:
+ this_leaf->attributes = CACHE_WRITE_THROUGH;
+ break;
+ case ACPI_6_2_CACHE_POLICY_WB:
+ this_leaf->attributes = CACHE_WRITE_BACK;
+ break;
+ default:
+ pr_err("Unknown ACPI cache policy %d\n",
+ found_cache->attributes & ACPI_PPTT_MASK_WRITE_POLICY);
+ }
+ if (found_cache->flags & ACPI_PPTT_ALLOCATION_TYPE_VALID)
+ switch (found_cache->attributes & ACPI_PPTT_MASK_ALLOCATION_TYPE) {
+ case ACPI_6_2_CACHE_READ_ALLOCATE:
+ this_leaf->attributes |= CACHE_READ_ALLOCATE;
+ break;
+ case ACPI_6_2_CACHE_WRITE_ALLOCATE:
+ this_leaf->attributes |= CACHE_WRITE_ALLOCATE;
+ break;
+ case ACPI_6_2_CACHE_RW_ALLOCATE:
+ this_leaf->attributes |=
+ CACHE_READ_ALLOCATE|CACHE_WRITE_ALLOCATE;
+ break;
+ default:
+ pr_err("Unknown ACPI cache allocation policy %d\n",
+ found_cache->attributes & ACPI_PPTT_MASK_ALLOCATION_TYPE);
+ }
+}
+
+static void cache_setup_acpi_cpu(struct acpi_table_header *table,
+ unsigned int cpu)
+{
+ struct acpi_pptt_cache *found_cache;
+ struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
+ u32 acpi_cpu_id = acpi_cpu_get_madt_gicc(cpu)->uid;
+ struct cacheinfo *this_leaf;
+ unsigned int index = 0;
+ struct acpi_pptt_processor *cpu_node = NULL;
+
+ while (index < get_cpu_cacheinfo(cpu)->num_leaves) {
cpu does not change, so, for efficiency, can you use
this_cpu_ci->num_leaves?
+ this_leaf = this_cpu_ci->info_list + index;
+ found_cache = acpi_find_cache_node(table, acpi_cpu_id,
+ this_leaf->type,
+ this_leaf->level,
+ &cpu_node);
+ pr_debug("found = %p %p\n", found_cache, cpu_node);
I am not sure how useful printing pointers is to the user, even if NULL.
Therse prints are too verbose.
+ if (found_cache)
+ update_cache_properties(this_leaf,
+ found_cache,
+ cpu_node);
+
+ index++;
+ }
+}
+
+static int topology_setup_acpi_cpu(struct acpi_table_header *table,
+ unsigned int cpu, int level)
+{
It's not clear what is suppossed to be returned from this function, if
anything, since it's job is seemingly to "setup"
+ struct acpi_pptt_processor *cpu_node;
+ u32 acpi_cpu_id = acpi_cpu_get_madt_gicc(cpu)->uid;
+
+ cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
+ if (cpu_node) {
+ cpu_node = acpi_find_processor_package_id(table, cpu_node, level);
+ /* Only the first level has a guaranteed id */
+ if (level == 0)
+ return cpu_node->acpi_processor_id;
+ return (int)((u8 *)cpu_node - (u8 *)table);
Sorry, but I just don't get this. As I understand, our intention is to
find the core/cluster/package index in the system for a given cpu, right?
If so, how is the distance between the table base and cpu level's node
the same as the system index? I would say that this value is unique, but
are we expecting sequential system indexing per level?
+ }
+ pr_err_once("PPTT table found, but unable to locate core for %d\n",
the code seems to intermix terms "core" and "cpu" - is this intentional?
+ cpu);
+ return -ENOENT;
+}
+
+/*
+ * simply assign a ACPI cache entry to each known CPU cache entry
+ * determining which entries are shared is done later.
+ */
+int cache_setup_acpi(unsigned int cpu)
+{
+ struct acpi_table_header *table;
+ acpi_status status;
+
+ pr_debug("Cache Setup ACPI cpu %d\n", cpu);
Please don't leave whitespace after "cpu"
+
+ status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
+ if (ACPI_FAILURE(status)) {
+ pr_err_once("No PPTT table found, cache topology may be inaccurate\n");
+ return -ENOENT;
+ }
+
+ cache_setup_acpi_cpu(table, cpu);
+ acpi_put_table(table);
+
+ return status;
+}
+
+/*
+ * Determine a topology unique ID for each thread/core/cluster/socket/etc.
+ * This ID can then be used to group peers.
+ */
+int setup_acpi_cpu_topology(unsigned int cpu, int level)
I think that you should add a function description to explain what cpu
and level are.
This function does no setup either. I think that doing a setup would be
doing something which has a persistent result. Instead, this function
gets the cpu topology index for a certain hierarchy level.
+{
+ struct acpi_table_header *table;
+ acpi_status status;
+ int retval;
+
+ status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
+ if (ACPI_FAILURE(status)) {
+ pr_err_once("No PPTT table found, cpu topology may be inaccurate\n");
As before, is this really an error?
+ return -ENOENT;
+ }
+ retval = topology_setup_acpi_cpu(table, cpu, level);
+ pr_debug("Topology Setup ACPI cpu %d, level %d ret = %d\n",
+ cpu, level, retval);
+ acpi_put_table(table);
+
+ return retval;
+}
Thanks,
John
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