[PATCH 03/33] ACPI / PPTT: Add acpi_pptt_cache_v1_full to use pptt cache as one structure

Ben Horgan
2025-11-07T12:35:44Z

In actbl2.h, struct acpi_pptt_cache describes the fields in the original
cache type structure. In PPTT table version 3 a new field was added at the
end, cache_id. This is described in struct acpi_pptt_cache_v1. Introduce
the new, acpi_pptt_cache_v1_full to contain both these structures. Update
the existing code to use this new struct. This simplifies the code, removes
a non-standard use of ACPI_ADD_PTR and allows using the length in the
header to check if the cache_id is valid.

Signed-off-by: Ben Horgan <ben.horgan@arm.com>
---
Changes since v3:
New patch
---
drivers/acpi/pptt.c | 104 ++++++++++++++++++++++++--------------------
1 file changed, 58 insertions(+), 46 deletions(-)

diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
index 1027ca3566b1..1ed2099c0d1a 100644
--- a/drivers/acpi/pptt.c
+++ b/drivers/acpi/pptt.c
@@ -21,6 +21,11 @@
#include <linux/cacheinfo.h>
#include <acpi/processor.h>

+struct acpi_pptt_cache_v1_full {
+ struct acpi_pptt_cache f;
+ struct acpi_pptt_cache_v1 extra;
+} __packed;
+
static struct acpi_subtable_header *fetch_pptt_subtable(struct acpi_table_header *table_hdr,
u32 pptt_ref)
{
@@ -50,10 +55,24 @@ static struct acpi_pptt_processor *fetch_pptt_node(struct acpi_table_header *tab
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)
+static struct acpi_pptt_cache_v1_full *fetch_pptt_cache(struct acpi_table_header *table_hdr,
+ u32 pptt_ref)
{
- return (struct acpi_pptt_cache *)fetch_pptt_subtable(table_hdr, pptt_ref);
+ return (struct acpi_pptt_cache_v1_full *)fetch_pptt_subtable(table_hdr, pptt_ref);
+}
+
+#define ACPI_PPTT_CACHE_V1_LEN sizeof(struct acpi_pptt_cache_v1_full)
+
+/*
+ * From PPTT table version 3, a new field cache_id was added at the end of
+ * the cache type structure. We now use struct acpi_pptt_cache_v1_full,
+ * containing the cache_id, everywhere but must check validity before accessing
+ * the cache_id.
+ */
+static bool acpi_pptt_cache_id_is_valid(struct acpi_pptt_cache_v1_full *cache)
+{
+ return (cache->f.header.length >= ACPI_PPTT_CACHE_V1_LEN &&
+ cache->f.flags & ACPI_PPTT_CACHE_ID_VALID);
}

static struct acpi_subtable_header *acpi_get_pptt_resource(struct acpi_table_header *table_hdr,
@@ -103,30 +122,30 @@ static unsigned int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
unsigned int local_level,
unsigned int *split_levels,
struct acpi_subtable_header *res,
- struct acpi_pptt_cache **found,
+ struct acpi_pptt_cache_v1_full **found,
unsigned int level, int type)
{
- struct acpi_pptt_cache *cache;
+ struct acpi_pptt_cache_v1_full *cache;

if (res->type != ACPI_PPTT_TYPE_CACHE)
return 0;

- cache = (struct acpi_pptt_cache *) res;
+ cache = (struct acpi_pptt_cache_v1_full *)res;
while (cache) {
local_level++;

- if (!(cache->flags & ACPI_PPTT_CACHE_TYPE_VALID)) {
- cache = fetch_pptt_cache(table_hdr, cache->next_level_of_cache);
+ if (!(cache->f.flags & ACPI_PPTT_CACHE_TYPE_VALID)) {
+ cache = fetch_pptt_cache(table_hdr, cache->f.next_level_of_cache);
continue;
}

if (split_levels &&
- (acpi_pptt_match_type(cache->attributes, ACPI_PPTT_CACHE_TYPE_DATA) ||
- acpi_pptt_match_type(cache->attributes, ACPI_PPTT_CACHE_TYPE_INSTR)))
+ (acpi_pptt_match_type(cache->f.attributes, ACPI_PPTT_CACHE_TYPE_DATA) ||
+ acpi_pptt_match_type(cache->f.attributes, ACPI_PPTT_CACHE_TYPE_INSTR)))
*split_levels = local_level;

if (local_level == level &&
- acpi_pptt_match_type(cache->attributes, type)) {
+ acpi_pptt_match_type(cache->f.attributes, type)) {
if (*found != NULL && cache != *found)
pr_warn("Found duplicate cache level/type unable to determine uniqueness\n");

@@ -138,12 +157,12 @@ static unsigned int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
* cache node.
*/
}
- cache = fetch_pptt_cache(table_hdr, cache->next_level_of_cache);
+ cache = fetch_pptt_cache(table_hdr, cache->f.next_level_of_cache);
}
return local_level;
}

-static struct acpi_pptt_cache *
+static struct acpi_pptt_cache_v1_full *
acpi_find_cache_level(struct acpi_table_header *table_hdr,
struct acpi_pptt_processor *cpu_node,
unsigned int *starting_level, unsigned int *split_levels,
@@ -152,7 +171,7 @@ acpi_find_cache_level(struct acpi_table_header *table_hdr,
struct acpi_subtable_header *res;
unsigned int number_of_levels = *starting_level;
int resource = 0;
- struct acpi_pptt_cache *ret = NULL;
+ struct acpi_pptt_cache_v1_full *ret = NULL;
unsigned int local_level;

/* walk down from processor node */
@@ -324,14 +343,14 @@ static u8 acpi_cache_type(enum cache_type type)
}
}

-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)
+static struct acpi_pptt_cache_v1_full *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)
{
unsigned int total_levels = 0;
- struct acpi_pptt_cache *found = NULL;
+ struct acpi_pptt_cache_v1_full *found = NULL;
struct acpi_pptt_processor *cpu_node;
u8 acpi_type = acpi_cache_type(type);

@@ -355,7 +374,6 @@ static struct acpi_pptt_cache *acpi_find_cache_node(struct acpi_table_header *ta
* @this_leaf: Kernel cache info structure being updated
* @found_cache: The PPTT node describing this cache instance
* @cpu_node: A unique reference to describe this cache instance
- * @revision: The revision of the PPTT table
*
* The ACPI spec implies that the fields in the cache structures are used to
* extend and correct the information probed from the hardware. Lets only
@@ -364,23 +382,20 @@ static struct acpi_pptt_cache *acpi_find_cache_node(struct acpi_table_header *ta
* Return: nothing. Side effect of updating the global cacheinfo
*/
static void update_cache_properties(struct cacheinfo *this_leaf,
- struct acpi_pptt_cache *found_cache,
- struct acpi_pptt_processor *cpu_node,
- u8 revision)
+ struct acpi_pptt_cache_v1_full *found_cache,
+ struct acpi_pptt_processor *cpu_node)
{
- struct acpi_pptt_cache_v1* found_cache_v1;
-
this_leaf->fw_token = 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) {
+ if (found_cache->f.flags & ACPI_PPTT_SIZE_PROPERTY_VALID)
+ this_leaf->size = found_cache->f.size;
+ if (found_cache->f.flags & ACPI_PPTT_LINE_SIZE_VALID)
+ this_leaf->coherency_line_size = found_cache->f.line_size;
+ if (found_cache->f.flags & ACPI_PPTT_NUMBER_OF_SETS_VALID)
+ this_leaf->number_of_sets = found_cache->f.number_of_sets;
+ if (found_cache->f.flags & ACPI_PPTT_ASSOCIATIVITY_VALID)
+ this_leaf->ways_of_associativity = found_cache->f.associativity;
+ if (found_cache->f.flags & ACPI_PPTT_WRITE_POLICY_VALID) {
+ switch (found_cache->f.attributes & ACPI_PPTT_MASK_WRITE_POLICY) {
case ACPI_PPTT_CACHE_POLICY_WT:
this_leaf->attributes = CACHE_WRITE_THROUGH;
break;
@@ -389,8 +404,8 @@ static void update_cache_properties(struct cacheinfo *this_leaf,
break;
}
}
- if (found_cache->flags & ACPI_PPTT_ALLOCATION_TYPE_VALID) {
- switch (found_cache->attributes & ACPI_PPTT_MASK_ALLOCATION_TYPE) {
+ if (found_cache->f.flags & ACPI_PPTT_ALLOCATION_TYPE_VALID) {
+ switch (found_cache->f.attributes & ACPI_PPTT_MASK_ALLOCATION_TYPE) {
case ACPI_PPTT_CACHE_READ_ALLOCATE:
this_leaf->attributes |= CACHE_READ_ALLOCATE;
break;
@@ -415,13 +430,11 @@ static void update_cache_properties(struct cacheinfo *this_leaf,
* specified in PPTT.
*/
if (this_leaf->type == CACHE_TYPE_NOCACHE &&
- found_cache->flags & ACPI_PPTT_CACHE_TYPE_VALID)
+ found_cache->f.flags & ACPI_PPTT_CACHE_TYPE_VALID)
this_leaf->type = CACHE_TYPE_UNIFIED;

- if (revision >= 3 && (found_cache->flags & ACPI_PPTT_CACHE_ID_VALID)) {
- found_cache_v1 = ACPI_ADD_PTR(struct acpi_pptt_cache_v1,
- found_cache, sizeof(struct acpi_pptt_cache));
- this_leaf->id = found_cache_v1->cache_id;
+ if (acpi_pptt_cache_id_is_valid(found_cache)) {
+ this_leaf->id = found_cache->extra.cache_id;
this_leaf->attributes |= CACHE_ID;
}
}
@@ -429,7 +442,7 @@ static void update_cache_properties(struct cacheinfo *this_leaf,
static void cache_setup_acpi_cpu(struct acpi_table_header *table,
unsigned int cpu)
{
- struct acpi_pptt_cache *found_cache;
+ struct acpi_pptt_cache_v1_full *found_cache;
struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu);
struct cacheinfo *this_leaf;
@@ -445,8 +458,7 @@ static void cache_setup_acpi_cpu(struct acpi_table_header *table,
pr_debug("found = %p %p\n", found_cache, cpu_node);
if (found_cache)
update_cache_properties(this_leaf, found_cache,
- ACPI_TO_POINTER(ACPI_PTR_DIFF(cpu_node, table)),
- table->revision);
+ ACPI_TO_POINTER(ACPI_PTR_DIFF(cpu_node, table)));

index++;
}
--
2.43.0