linux-kernel - [PATCH v3 2/2] tpm: Add reserved memory event log

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Message-Id: <20230126210810.881119-3-eajames@linux.ibm.com>
Date:   Thu, 26 Jan 2023 15:08:10 -0600
From:   Eddie James <eajames@...ux.ibm.com>
To:     linux-integrity@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        peterhuewe@....de, jarkko@...nel.org, jgg@...pe.ca,
        stefanb@...ux.ibm.com, eajames@...ux.ibm.com
Subject: [PATCH v3 2/2] tpm: Add reserved memory event log

Some platforms may desire to pass the event log up to Linux in the
form of a reserved memory region. In particular, this is desirable
for embedded systems or baseboard management controllers (BMCs)
booting with U-Boot. IBM OpenBMC BMCs will be the first user.
Add support for the reserved memory in the TPM core to find the
region and map it.

Signed-off-by: Eddie James <eajames@...ux.ibm.com>
---
 drivers/char/tpm/eventlog/of.c | 38 +++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c
index 741ab2204b11..c815cadf00a4 100644
--- a/drivers/char/tpm/eventlog/of.c
+++ b/drivers/char/tpm/eventlog/of.c
@@ -12,12 +12,48 @@
 
 #include <linux/device.h>
 #include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_reserved_mem.h>
 #include <linux/tpm_eventlog.h>
 
 #include "../tpm.h"
 #include "common.h"
 
+static int tpm_read_log_memory_region(struct tpm_chip *chip)
+{
+	struct device_node *node;
+	struct resource res;
+	int rc;
+
+	node = of_parse_phandle(chip->dev.parent->of_node, "memory-region", 0);
+	if (!node) {
+		dev_info(&chip->dev, "no phandle\n");
+		return -ENODEV;
+	}
+
+	rc = of_address_to_resource(node, 0, &res);
+	of_node_put(node);
+	if (rc) {
+		dev_info(&chip->dev, "no mem\n");
+		return rc;
+	}
+
+	chip->log.bios_event_log = devm_memremap(&chip->dev, res.start, resource_size(&res),
+						 MEMREMAP_WB);
+	if (!chip->log.bios_event_log) {
+		dev_info(&chip->dev, "err memremap\n");
+		return -ENOMEM;
+	}
+
+	chip->log.bios_event_log_end = chip->log.bios_event_log + resource_size(&res);
+
+	return chip->flags & TPM_CHIP_FLAG_TPM2 ? EFI_TCG2_EVENT_LOG_FORMAT_TCG_2 :
+		EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
+}
+
 int tpm_read_log_of(struct tpm_chip *chip)
 {
 	struct device_node *np;
@@ -39,7 +75,7 @@ int tpm_read_log_of(struct tpm_chip *chip)
 	sizep = of_get_property(np, "linux,sml-size", NULL);
 	basep = of_get_property(np, "linux,sml-base", NULL);
 	if (sizep == NULL && basep == NULL)
-		return -ENODEV;
+		return tpm_read_log_memory_region(chip);
 	if (sizep == NULL || basep == NULL)
 		return -EIO;
 
-- 
2.31.1