[PATCH] tpm: remove redundant code from self-test functions

From: Jarkko Sakkinen
Date: Wed Mar 30 2016 - 01:38:15 EST


Self-test functions construct PCR read calls by ad hoc, which is only a
waste space. Use instead tpm_pcr_read_dev (renamed as tpm1_pcr_read() by
this commit) in tpm_do_selftest and tpm2_pcr_read() in
tpm2_do_selftest() functions in order to remove the duplicate code.

Patch can be tested easily tested by running the a kernel with this
patch compiled in since self-test is done when the a device driver
initializes.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
drivers/char/tpm/tpm-interface.c | 14 +++++---------
drivers/char/tpm/tpm2-cmd.c | 14 ++------------
2 files changed, 7 insertions(+), 21 deletions(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 5397b64..0c8140f 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -1,6 +1,6 @@
/*
* Copyright (C) 2004 IBM Corporation
- * Copyright (C) 2014 Intel Corporation
+ * Copyright (C) 2014, 2016 Intel Corporation
*
* Authors:
* Leendert van Doorn <leendert@xxxxxxxxxxxxxx>
@@ -666,7 +666,7 @@ static struct tpm_input_header pcrread_header = {
.ordinal = TPM_ORDINAL_PCRREAD
};

-int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
+int tpm1_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
{
int rc;
struct tpm_cmd_t cmd;
@@ -676,7 +676,7 @@ int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
rc = tpm_transmit_cmd(chip, &cmd, READ_PCR_RESULT_SIZE,
"attempting to read a pcr value");

- if (rc == 0)
+ if (rc == 0 && res_buf)
memcpy(res_buf, cmd.params.pcrread_out.pcr_result,
TPM_DIGEST_SIZE);
return rc;
@@ -728,7 +728,7 @@ int tpm_pcr_read(u32 chip_num, int pcr_idx, u8 *res_buf)
if (chip->flags & TPM_CHIP_FLAG_TPM2)
rc = tpm2_pcr_read(chip, pcr_idx, res_buf);
else
- rc = tpm_pcr_read_dev(chip, pcr_idx, res_buf);
+ rc = tpm1_pcr_read(chip, pcr_idx, res_buf);
tpm_put_ops(chip);
return rc;
}
@@ -793,7 +793,6 @@ int tpm_do_selftest(struct tpm_chip *chip)
unsigned int loops;
unsigned int delay_msec = 100;
unsigned long duration;
- struct tpm_cmd_t cmd;

duration = tpm_calc_ordinal_duration(chip, TPM_ORD_CONTINUE_SELFTEST);

@@ -808,9 +807,7 @@ int tpm_do_selftest(struct tpm_chip *chip)

do {
/* Attempt to read a PCR value */
- cmd.header.in = pcrread_header;
- cmd.params.pcrread_in.pcr_idx = cpu_to_be32(0);
- rc = tpm_transmit(chip, (u8 *) &cmd, READ_PCR_RESULT_SIZE);
+ rc = tpm1_pcr_read(chip, 0, NULL);
/* Some buggy TPMs will not respond to tpm_tis_ready() for
* around 300ms while the self test is ongoing, keep trying
* until the self test duration expires. */
@@ -825,7 +822,6 @@ int tpm_do_selftest(struct tpm_chip *chip)
if (rc < TPM_HEADER_SIZE)
return -EFAULT;

- rc = be32_to_cpu(cmd.header.out.return_code);
if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {
dev_info(&chip->dev,
"TPM is disabled/deactivated (0x%X)\n", rc);
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 5fc0e7c..afe8d47 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -284,7 +284,7 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)

rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd),
"attempting to read a pcr value");
- if (rc == 0) {
+ if (rc == 0 && res_buf) {
buf = cmd.params.pcrread_out.digest;
memcpy(res_buf, buf, TPM_DIGEST_SIZE);
}
@@ -861,7 +861,6 @@ int tpm2_do_selftest(struct tpm_chip *chip)
unsigned int loops;
unsigned int delay_msec = 100;
unsigned long duration;
- struct tpm2_cmd cmd;
int i;

duration = tpm2_calc_ordinal_duration(chip, TPM2_CC_SELF_TEST);
@@ -874,19 +873,10 @@ int tpm2_do_selftest(struct tpm_chip *chip)

for (i = 0; i < loops; i++) {
/* Attempt to read a PCR value */
- cmd.header.in = tpm2_pcrread_header;
- cmd.params.pcrread_in.pcr_selects_cnt = cpu_to_be32(1);
- cmd.params.pcrread_in.hash_alg = cpu_to_be16(TPM2_ALG_SHA1);
- cmd.params.pcrread_in.pcr_select_size = TPM2_PCR_SELECT_MIN;
- cmd.params.pcrread_in.pcr_select[0] = 0x01;
- cmd.params.pcrread_in.pcr_select[1] = 0x00;
- cmd.params.pcrread_in.pcr_select[2] = 0x00;
-
- rc = tpm_transmit_cmd(chip, (u8 *) &cmd, sizeof(cmd), NULL);
+ rc = tpm2_pcr_read(chip, 0, NULL);
if (rc < 0)
break;

- rc = be32_to_cpu(cmd.header.out.return_code);
if (rc != TPM2_RC_TESTING)
break;

--
2.7.3