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

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Message-Id: <20230103162010.381214-1-eajames@linux.ibm.com>
Date:   Tue,  3 Jan 2023 10:20:10 -0600
From:   Eddie James <eajames@...ux.ibm.com>
To:     linux-integrity@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, jgg@...pe.ca, jarkko@...nel.org,
        peterhuewe@....de, joel@....id.au,
        Eddie James <eajames@...ux.ibm.com>
Subject: [PATCH] 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. Add support for this in the TPM
core to find the reserved memory region and map it.

Signed-off-by: Eddie James <eajames@...ux.ibm.com>
---
 drivers/char/tpm/eventlog/of.c | 38 +++++++++++++++++++++++++++++++++-
 drivers/char/tpm/tpm-chip.c    |  3 ++-
 include/linux/tpm.h            |  1 +
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c
index a9ce66d09a75..0455d7f61c10 100644
--- a/drivers/char/tpm/eventlog/of.c
+++ b/drivers/char/tpm/eventlog/of.c
@@ -11,12 +11,48 @@
  */
 
 #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 = memremap(res.start, resource_size(&res), MEMREMAP_WB);
+	if (!chip->log.bios_event_log) {
+		dev_info(&chip->dev, "err memremap\n");
+		return -ENOMEM;
+	}
+
+	chip->log.release = memunmap;
+	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;
@@ -38,7 +74,7 @@ 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;
 
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 741d8f3e8fb3..09ea8145d7c6 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -267,7 +267,7 @@ static void tpm_dev_release(struct device *dev)
 	idr_remove(&dev_nums_idr, chip->dev_num);
 	mutex_unlock(&idr_lock);
 
-	kfree(chip->log.bios_event_log);
+	chip->log.release(chip->log.bios_event_log);
 	kfree(chip->work_space.context_buf);
 	kfree(chip->work_space.session_buf);
 	kfree(chip->allocated_banks);
@@ -324,6 +324,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
 	init_rwsem(&chip->ops_sem);
 
 	chip->ops = ops;
+	chip->log.release = (void(*)(void *))kfree;
 
 	mutex_lock(&idr_lock);
 	rc = idr_alloc(&dev_nums_idr, NULL, 0, TPM_NUM_DEVICES, GFP_KERNEL);
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index dfeb25a0362d..f1c0b0eb20a5 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -109,6 +109,7 @@ struct tpm_space {
 struct tpm_bios_log {
 	void *bios_event_log;
 	void *bios_event_log_end;
+	void (*release)(void *ptr);
 };
 
 struct tpm_chip_seqops {
-- 
2.31.1