Re: [PATCH v4 4/7] tpm: tpm_tis: Fix expected bit handling and send all bytes in one shot without last byte in exception

[Jarkko Sakkinen]

On Tue, Mar 31, 2020 at 02:32:04PM +0300, amirmizi6@xxxxxxxxx wrote:
> From: Amir Mizinski <amirmizi6@xxxxxxxxx>
> 
> Today, actual implementation for send massage is not correct. We check and
> loop only on TPM_STS.stsValid bit and next we single check TPM_STS.expect
> bit value.
> TPM_STS.expected bit shall be checked in the same time of
> TPM_STS.stsValid, and should be repeated until timeout_A.
> To aquire that, "wait_for_tpm_stat" function is modified to
> "wait_for_tpm_stat_result". this function read regulary status register
> and check bit defined by "mask" to reach value defined in "mask_result"
> (that way a bit in mask can be checked if reached 1 or 0).
> 
> Respectively, to send message as defined in
> TCG_DesignPrinciples_TPM2p0Driver_vp24_pubrev.pdf, all bytes should be
> sent in one shot instead of sending last byte in exception.
> 
> This improvment was suggested by Benoit Houyere.

Use suggested-by tag.

Also if something is not correct, please provide a fixes tag.

You are speaking now in theoretical level, which we don't really
care that much. Is this causing you real issues? If the answer is
yes, please report them. If the answer is no, we don't need this.

/Jarkko

> 
> Signed-off-by: Amir Mizinski <amirmizi6@xxxxxxxxx>
> ---
>  drivers/char/tpm/tpm_tis_core.c | 72 ++++++++++++++++-------------------------
>  1 file changed, 28 insertions(+), 44 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 18b9dc4..c8f4cf8 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -44,9 +44,10 @@ 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 wait_for_tpm_stat_result(struct tpm_chip *chip, u8 mask,
> +                                   u8 mask_result, unsigned long timeout,
> +                                   wait_queue_head_t *queue,
> +                                   bool check_cancel)
>  {
>         unsigned long stop;
>         long rc;
> @@ -55,7 +56,7 @@ 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) == mask_result)
>                 return 0;
> 
>         stop = jiffies + timeout;
> @@ -83,7 +84,7 @@ 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) == mask_result)
>                                 return 0;
>                 } while (time_before(jiffies, stop));
>         }
> @@ -290,10 +291,11 @@ 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 = wait_for_tpm_stat_result(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);
> @@ -348,8 +350,9 @@ 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 (wait_for_tpm_stat_result(chip, TPM_STS_VALID,
> +                                            TPM_STS_VALID, chip->timeout_c,
> +                                            &priv->int_queue, false) < 0) {
>                         size = -ETIME;
>                         goto out;
>                 }
> @@ -385,61 +388,40 @@ 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 (wait_for_tpm_stat_result(chip, TPM_STS_COMMAND_READY,
> +                                            TPM_STS_COMMAND_READY,
> +                                            chip->timeout_b,
> +                                            &priv->int_queue, false) < 0) {
>                         rc = -ETIME;
>                         goto out_err;
>                 }
>         }
> 
> -       while (count < len - 1) {
> +       while (count < len) {
>                 burstcnt = get_burstcount(chip);
>                 if (burstcnt < 0) {
>                         dev_err(&chip->dev, "Unable to read burstcount\n");
>                         rc = burstcnt;
>                         goto out_err;
>                 }
> -               burstcnt = min_t(int, burstcnt, len - count - 1);
> +               burstcnt = min_t(int, burstcnt, len - count);
>                 rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality),
>                                          burstcnt, buf + count);
>                 if (rc < 0)
>                         goto out_err;
> 
>                 count += burstcnt;
> -
> -               if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
> -                                       &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 (wait_for_tpm_stat_result(chip, TPM_STS_VALID | TPM_STS_DATA_EXPECT,
> +                                    TPM_STS_VALID, chip->timeout_c,
> +                                    &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;
> 
> @@ -496,9 +478,11 @@ 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 (wait_for_tpm_stat_result(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
> 
> 
> 
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