linux-kernel - Re: [tpmdd-devel] [PATCH v3 2/4] tpm: Add optional logging of TPM command durations

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Date:	Tue, 7 Jun 2016 17:01:03 +0300
From:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:	Ed Swierk <eswierk@...portsystems.com>
Cc:	tpmdd-devel@...ts.sourceforge.net,
	linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [tpmdd-devel] [PATCH v3 2/4] tpm: Add optional logging of TPM
 command durations

On Mon, Jun 06, 2016 at 08:37:27PM -0700, Ed Swierk wrote:
> Some TPMs violate their own advertised command durations. This is much
> easier to debug with data about how long each command actually takes
> to complete. Add debug messages that can be enabled by running
> 
>   echo -n 'module tpm +p' >/sys/kernel/debug/dynamic_debug/control
> 
> on a kernel configured with DYNAMIC_DEBUG=y.
> 
> Signed-off-by: Ed Swierk <eswierk@...portsystems.com>

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>

> ---
>  drivers/char/tpm/tpm-interface.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index c50637d..cc1e5bc 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -333,13 +333,14 @@ ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,
>  {
>  	ssize_t rc;
>  	u32 count, ordinal;
> -	unsigned long stop;
> +	unsigned long start, stop;
>  
>  	if (bufsiz > TPM_BUFSIZE)
>  		bufsiz = TPM_BUFSIZE;
>  
>  	count = be32_to_cpu(*((__be32 *) (buf + 2)));
>  	ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
> +	dev_dbg(chip->pdev, "starting command %d count %d\n", ordinal, count);
>  	if (count == 0)
>  		return -ENODATA;
>  	if (count > bufsiz) {
> @@ -360,18 +361,24 @@ ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,
>  	if (chip->vendor.irq)
>  		goto out_recv;
>  
> +	start = jiffies;
>  	if (chip->flags & TPM_CHIP_FLAG_TPM2)
> -		stop = jiffies + tpm2_calc_ordinal_duration(chip, ordinal);
> +		stop = start + tpm2_calc_ordinal_duration(chip, ordinal);
>  	else
> -		stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
> +		stop = start + tpm_calc_ordinal_duration(chip, ordinal);
>  	do {
>  		u8 status = chip->ops->status(chip);
>  		if ((status & chip->ops->req_complete_mask) ==
> -		    chip->ops->req_complete_val)
> +		    chip->ops->req_complete_val) {
> +			dev_dbg(chip->pdev, "completed command %d in %d ms\n",
> +				ordinal, jiffies_to_msecs(jiffies - start));
>  			goto out_recv;
> +		}
>  
>  		if (chip->ops->req_canceled(chip, status)) {
>  			dev_err(chip->pdev, "Operation Canceled\n");
> +			dev_dbg(chip->pdev, "canceled command %d after %d ms\n",
> +				ordinal, jiffies_to_msecs(jiffies - start));
>  			rc = -ECANCELED;
>  			goto out;
>  		}
> @@ -382,6 +389,8 @@ ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,
>  
>  	chip->ops->cancel(chip);
>  	dev_err(chip->pdev, "Operation Timed out\n");
> +	dev_dbg(chip->pdev, "command %d timed out after %d ms\n", ordinal,
> +		jiffies_to_msecs(jiffies - start));
>  	rc = -ETIME;
>  	goto out;
>  
> -- 
> 1.9.1
> 
> 
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/Jarkko