[RFC v2 2/5] acpi: HMAT support in acpi_parse_entries_array()

Ross Zwisler
2017-07-06T21:52:49Z

The current implementation of acpi_parse_entries_array() assumes that each
subtable has a standard ACPI subtable entry of type struct
acpi_sutbable_header. This standard subtable header has a one byte length
followed by a one byte type.

The HMAT subtables have to allow for a longer length so they have subtable
headers of type struct acpi_hmat_structure which has a 2 byte type and a 4
byte length.

Enhance the subtable parsing in acpi_parse_entries_array() so that it can
handle these new HMAT subtables.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
drivers/acpi/numa.c | 2 +-
drivers/acpi/tables.c | 52 ++++++++++++++++++++++++++++++++++++++++-----------
2 files changed, 42 insertions(+), 12 deletions(-)

diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
index edb0c79..917f1cc 100644
--- a/drivers/acpi/numa.c
+++ b/drivers/acpi/numa.c
@@ -443,7 +443,7 @@ int __init acpi_numa_init(void)
* So go over all cpu entries in SRAT to get apicid to node mapping.
*/

- /* SRAT: Static Resource Affinity Table */
+ /* SRAT: System Resource Affinity Table */
if (!acpi_table_parse(ACPI_SIG_SRAT, acpi_parse_srat)) {
struct acpi_subtable_proc srat_proc[3];

diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index ff42539..7979171 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -218,6 +218,33 @@ void acpi_table_print_madt_entry(struct acpi_subtable_header *header)
}
}

+static unsigned long __init
+acpi_get_entry_type(char *id, void *entry)
+{
+ if (!strncmp(id, ACPI_SIG_HMAT, 4))
+ return ((struct acpi_hmat_structure *)entry)->type;
+ else
+ return ((struct acpi_subtable_header *)entry)->type;
+}
+
+static unsigned long __init
+acpi_get_entry_length(char *id, void *entry)
+{
+ if (!strncmp(id, ACPI_SIG_HMAT, 4))
+ return ((struct acpi_hmat_structure *)entry)->length;
+ else
+ return ((struct acpi_subtable_header *)entry)->length;
+}
+
+static unsigned long __init
+acpi_get_subtable_header_length(char *id)
+{
+ if (!strncmp(id, ACPI_SIG_HMAT, 4))
+ return sizeof(struct acpi_hmat_structure);
+ else
+ return sizeof(struct acpi_subtable_header);
+}
+
/**
* acpi_parse_entries_array - for each proc_num find a suitable subtable
*
@@ -242,10 +269,10 @@ acpi_parse_entries_array(char *id, unsigned long table_size,
struct acpi_subtable_proc *proc, int proc_num,
unsigned int max_entries)
{
- struct acpi_subtable_header *entry;
- unsigned long table_end;
+ unsigned long table_end, subtable_header_length;
int count = 0;
int errs = 0;
+ void *entry;
int i;

if (acpi_disabled)
@@ -263,19 +290,23 @@ acpi_parse_entries_array(char *id, unsigned long table_size,
}

table_end = (unsigned long)table_header + table_header->length;
+ subtable_header_length = acpi_get_subtable_header_length(id);

/* Parse all entries looking for a match. */

- entry = (struct acpi_subtable_header *)
- ((unsigned long)table_header + table_size);
+ entry = (void *)table_header + table_size;
+
+ while (((unsigned long)entry) + subtable_header_length < table_end) {
+ unsigned long entry_type, entry_length;

- while (((unsigned long)entry) + sizeof(struct acpi_subtable_header) <
- table_end) {
if (max_entries && count >= max_entries)
break;

+ entry_type = acpi_get_entry_type(id, entry);
+ entry_length = acpi_get_entry_length(id, entry);
+
for (i = 0; i < proc_num; i++) {
- if (entry->type != proc[i].id)
+ if (entry_type != proc[i].id)
continue;
if (!proc[i].handler ||
(!errs && proc[i].handler(entry, table_end))) {
@@ -290,16 +321,15 @@ acpi_parse_entries_array(char *id, unsigned long table_size,
count++;

/*
- * If entry->length is 0, break from this loop to avoid
+ * If entry_length is 0, break from this loop to avoid
* infinite loop.
*/
- if (entry->length == 0) {
+ if (entry_length == 0) {
pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
return -EINVAL;
}

- entry = (struct acpi_subtable_header *)
- ((unsigned long)entry + entry->length);
+ entry += entry_length;
}

if (max_entries && count > max_entries) {
--
2.9.4