linux-kernel - [PATCH v2 3/3] tpm: Add support for ACPI logs from TPM2 ACPI table

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Date:   Mon, 30 Mar 2020 11:15:36 -0400
From:   Stefan Berger <stefanb@...ux.vnet.ibm.com>
To:     linux-integrity@...r.kernel.org, jarkko.sakkinen@...ux.intel.com,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-security-module@...r.kernel.org
Cc:     Stefan Berger <stefanb@...ux.ibm.com>
Subject: [PATCH v2 3/3] tpm: Add support for ACPI logs from TPM2 ACPI table

From: Stefan Berger <stefanb@...ux.ibm.com>

In case of a TPM2 search for a TPM2 ACPI table and if found use it to
find start and length of the log area.

Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
---
 drivers/char/tpm/eventlog/acpi.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/eventlog/acpi.c b/drivers/char/tpm/eventlog/acpi.c
index 1ef2267c9378..2447f21e4a23 100644
--- a/drivers/char/tpm/eventlog/acpi.c
+++ b/drivers/char/tpm/eventlog/acpi.c
@@ -49,6 +49,8 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
 	void __iomem *virt;
 	u64 len, start;
 	struct tpm_bios_log *log;
+	struct acpi_table_tpm2 *tbl;
+	int format;
 
 	log = &chip->log;
 
@@ -59,7 +61,15 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
 		return -ENODEV;
 
 	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
-		return -ENODEV;
+		status = acpi_get_table("TPM2", 1,
+					(struct acpi_table_header **)&tbl);
+		if (ACPI_FAILURE(status))
+			return -ENODEV;
+		if (tbl->header.length < sizeof(*tbl))
+			return -ENODEV;
+		len = tbl->log_area_minimum_length;
+		start = tbl->log_area_start_address;
+		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,
@@ -79,6 +89,7 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
 			start = buff->client.log_start_addr;
 			break;
 		}
+		format = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
 	}
 	if (!len) {
 		dev_warn(&chip->dev, "%s: TCPA log area empty\n", __func__);
@@ -99,7 +110,7 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
 	memcpy_fromio(log->bios_event_log, virt, len);
 
 	acpi_os_unmap_iomem(virt, len);
-	return EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
+	return format;
 
 err:
 	kfree(log->bios_event_log);
-- 
2.14.5