From: Amir Mizinski <amirmizi6@xxxxxxxxx>
Currently, the driver polls the TPM_STS.stsValid field until TRUE; then it
reads TPM_STS register again to verify only that TPM_STS.expect field is
FALSE (i.e., it ignores TPM_STS.stsValid).
Since TPM_STS.stsValid represents the TPM_STS.expect validity, a check of
only one of these fields is wrong. Fix this condition so that both fields
are checked in the same TPM_STS register read.
Modify the signature of wait_for_tpm_stat() to tpm_tis_wait_for_stat(),
adding an additional "expected" parameter to its call.
tpm_tis_wait_for_stat() is now polling the TPM_STS with a mask and waits
for the value in "expected". This modification adds the ability to check if
certain TPM_STS bits have been cleared.
For example, use the new parameter to check in status that TPM_STS_VALID
is set and also that TPM_STS_EXPECT is zeroed. This prevents a racy
check.
Suggested-by: Benoit Houyere <benoit.houyere@xxxxxx>
Signed-off-by: Amir Mizinski <amirmizi6@xxxxxxxxx>
---
drivers/char/tpm/tpm_tis_core.c | 61 ++++++++++++++++++-----------------------
1 file changed, 27 insertions(+), 34 deletions(-)
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 69579ef..f833f35 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -44,9 +44,9 @@ static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
return false;
}
-static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
- unsigned long timeout, wait_queue_head_t *queue,
- bool check_cancel)
+static int tpm_tis_wait_for_stat(struct tpm_chip *chip, u8 mask, u8 expected,
+ unsigned long timeout,
+ wait_queue_head_t *queue, bool check_cancel)
{
unsigned long stop;
long rc;
@@ -55,7 +55,7 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
/* check current status */
status = chip->ops->status(chip);
- if ((status & mask) == mask)
+ if ((status & mask) == expected)
return 0;
stop = jiffies + timeout;
@@ -83,7 +83,7 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
usleep_range(TPM_TIMEOUT_USECS_MIN,
TPM_TIMEOUT_USECS_MAX);
status = chip->ops->status(chip);
- if ((status & mask) == mask)
+ if ((status & mask) == expected)
return 0;
} while (time_before(jiffies, stop));
}
@@ -259,10 +259,11 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
int size = 0, burstcnt, rc;
while (size < count) {
- rc = wait_for_tpm_stat(chip,
- TPM_STS_DATA_AVAIL | TPM_STS_VALID,
- chip->timeout_c,
- &priv->read_queue, true);
+ rc = tpm_tis_wait_for_stat(chip,
+ TPM_STS_DATA_AVAIL | TPM_STS_VALID,
+ TPM_STS_DATA_AVAIL | TPM_STS_VALID,
+ chip->timeout_c, &priv->read_queue,
+ true);
if (rc < 0)
return rc;
burstcnt = get_burstcount(chip);
@@ -315,8 +316,9 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
goto out;
}
- if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
- &priv->int_queue, false) < 0) {
+ if (tpm_tis_wait_for_stat(chip, TPM_STS_VALID, TPM_STS_VALID,
+ chip->timeout_c, &priv->int_queue,
+ false) < 0) {
size = -ETIME;
goto out;
}
@@ -342,14 +344,14 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
int rc, status, burstcnt;
size_t count = 0;
- bool itpm = priv->flags & TPM_TIS_ITPM_WORKAROUND;
status = tpm_tis_status(chip);
if ((status & TPM_STS_COMMAND_READY) == 0) {
tpm_tis_ready(chip);
- if (wait_for_tpm_stat
- (chip, TPM_STS_COMMAND_READY, chip->timeout_b,
- &priv->int_queue, false) < 0) {
+ if (tpm_tis_wait_for_stat(chip, TPM_STS_COMMAND_READY,
+ TPM_STS_COMMAND_READY,
+ chip->timeout_b, &priv->int_queue,
+ false) < 0) {
rc = -ETIME;
goto out_err;
}
@@ -369,34 +371,24 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
goto out_err;
count += burstcnt;
-
- if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
- &priv->int_queue, false) < 0) {
+ if (tpm_tis_wait_for_stat(chip, TPM_STS_VALID | TPM_STS_DATA_EXPECT,
+ TPM_STS_VALID | TPM_STS_DATA_EXPECT, chip->timeout_a,
+ &priv->int_queue, false) < 0) {
rc = -ETIME;
goto out_err;
}
- status = tpm_tis_status(chip);
- if (!itpm && (status & TPM_STS_DATA_EXPECT) == 0) {
- rc = -EIO;
- goto out_err;
- }
}
/* write last byte */
rc = tpm_tis_write8(priv, TPM_DATA_FIFO(priv->locality), buf[count]);
if (rc < 0)
goto out_err;
-
- if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
- &priv->int_queue, false) < 0) {
+ if (tpm_tis_wait_for_stat(chip, TPM_STS_VALID | TPM_STS_DATA_EXPECT,
+ TPM_STS_VALID, chip->timeout_a,
+ &priv->int_queue, false) < 0) {
rc = -ETIME;
goto out_err;
}
- status = tpm_tis_status(chip);
- if (!itpm && (status & TPM_STS_DATA_EXPECT) != 0) {
- rc = -EIO;
- goto out_err;
- }
return 0;
@@ -451,9 +443,10 @@ static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
dur = tpm_calc_ordinal_duration(chip, ordinal);
- if (wait_for_tpm_stat
- (chip, TPM_STS_DATA_AVAIL | TPM_STS_VALID, dur,
- &priv->read_queue, false) < 0) {
+ if (tpm_tis_wait_for_stat(chip,
+ TPM_STS_DATA_AVAIL | TPM_STS_VALID,
+ TPM_STS_DATA_AVAIL | TPM_STS_VALID,
+ dur, &priv->read_queue, false) < 0) {
rc = -ETIME;
goto out_err;
}
--
2.7.4
