The Confidential Computing Event Log (CCEL) table provides the address
and length of the CCEL records area in UEFI reserved memory. To access
these records, userspace can use /dev/mem to retrieve them. But
'/dev/mem' is not enabled on many systems for security reasons.
So to allow user space access these event log records without the
/dev/mem interface, add support to access it via sysfs interface. The
ACPI driver has provided read only access to BERT records area via
'/sys/firmware/acpi/tables/data/BERT' in sysfs. So follow the same way,
and add support for /sys/firmware/acpi/tables/data/CCEL to enable
read-only access to the CCEL recorids area.
More details about the CCEL table can be found in ACPI specification
r6.5, sec titled "CC Event Log ACPI Table".
Original-patch-by: Haibo Xu <haibo1.xu@xxxxxxxxx>
[Original patch is for TDEL table, modified it for CCEL support]
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
---
Changes since v1:
* Removed unnecessary parenthesis as per Rafael's suggestion..
drivers/acpi/sysfs.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
index 7f4ff56c9d42..687524b50085 100644
--- a/drivers/acpi/sysfs.c
+++ b/drivers/acpi/sysfs.c
@@ -458,11 +458,28 @@ static int acpi_bert_data_init(void *th, struct acpi_data_attr *data_attr)
return sysfs_create_bin_file(tables_data_kobj, &data_attr->attr);
}
+static int acpi_ccel_data_init(void *th, struct acpi_data_attr *data_attr)
+{
+ struct acpi_table_ccel *ccel = th;
+
+ if (ccel->header.length < sizeof(struct acpi_table_ccel) ||
+ !ccel->log_area_start_address || !ccel->log_area_minimum_length) {
+ kfree(data_attr);
+ return -EINVAL;
+ }
+ data_attr->addr = ccel->log_area_start_address;
+ data_attr->attr.size = ccel->log_area_minimum_length;
+ data_attr->attr.attr.name = "CCEL";
+
+ return sysfs_create_bin_file(tables_data_kobj, &data_attr->attr);
+}
+
static struct acpi_data_obj {
char *name;
int (*fn)(void *, struct acpi_data_attr *);
} acpi_data_objs[] = {
{ ACPI_SIG_BERT, acpi_bert_data_init },
+ { ACPI_SIG_CCEL, acpi_ccel_data_init },
};
#define NUM_ACPI_DATA_OBJS ARRAY_SIZE(acpi_data_objs)
--
2.34.1
