drivers/char/tpm/eventlog/acpi.c

Source file repositories/reference/linux-study-clean/drivers/char/tpm/eventlog/acpi.c

File Facts

System
Linux kernel
Corpus path
drivers/char/tpm/eventlog/acpi.c
Extension
.c
Size
4188 bytes
Lines
182
Domain
Driver Families
Bucket
drivers/char
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct acpi_tcpa {
	struct acpi_table_header hdr;
	u16 platform_class;
	union {
		struct client_hdr {
			u32 log_max_len __packed;
			u64 log_start_addr __packed;
		} client;
		struct server_hdr {
			u16 reserved;
			u64 log_max_len __packed;
			u64 log_start_addr __packed;
		} server;
	};
};

/* Check that the given log is indeed a TPM2 log. */
static bool tpm_is_tpm2_log(void *bios_event_log, u64 len)
{
	struct tcg_efi_specid_event_head *efispecid;
	struct tcg_pcr_event *event_header;
	int n;

	if (len < sizeof(*event_header))
		return false;
	len -= sizeof(*event_header);
	event_header = bios_event_log;

	if (len < sizeof(*efispecid))
		return false;
	efispecid = (struct tcg_efi_specid_event_head *)event_header->event;

	n = memcmp(efispecid->signature, TCG_SPECID_SIG,
		   sizeof(TCG_SPECID_SIG));
	return n == 0;
}

static void tpm_bios_log_free(void *data)
{
	kvfree(data);
}

/* read binary bios log */
int tpm_read_log_acpi(struct tpm_chip *chip)
{
	struct acpi_tcpa *buff;
	acpi_status status;
	void __iomem *virt;
	u64 len, start;
	struct tpm_bios_log *log;
	struct acpi_table_tpm2 *tbl;
	struct acpi_tpm2_phy *tpm2_phy;
	int format;
	int ret;

	log = &chip->log;

	/* Unfortuntely ACPI does not associate the event log with a specific
	 * TPM, like PPI. Thus all ACPI TPMs will read the same log.
	 */
	if (!chip->acpi_dev_handle)
		return -ENODEV;

	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
		status = acpi_get_table("TPM2", 1,
					(struct acpi_table_header **)&tbl);
		if (ACPI_FAILURE(status))
			return -ENODEV;

		if (tbl->header.length <
				sizeof(*tbl) + sizeof(struct acpi_tpm2_phy)) {
			acpi_put_table((struct acpi_table_header *)tbl);
			return -ENODEV;
		}

		tpm2_phy = (void *)tbl + sizeof(*tbl);
		len = tpm2_phy->log_area_minimum_length;

		start = tpm2_phy->log_area_start_address;
		if (!start || !len) {
			acpi_put_table((struct acpi_table_header *)tbl);
			return -ENODEV;
		}

		acpi_put_table((struct acpi_table_header *)tbl);
		format = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2;
	} else {
		/* Find TCPA entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
		status = acpi_get_table(ACPI_SIG_TCPA, 1,
					(struct acpi_table_header **)&buff);

Annotation

Implementation Notes