Re: [PATCH 2/4] Read TCG log from TPM2 table

[Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Wed, Mar 29, 2017 at 12:43:26AM -0700, Petr Vandrovec wrote:
> From: Petr Vandrovec <petr-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
> 
> Latest draft of TPM 2 ACPI specification added TCG log start/length
> to the TPM2 ACPI table.  So Linux kernel can now read it without
> having to get involved with boot loader, same way TPM1/TCPA tables
> work.
> 
> Signed-off-by: Petr Vandrovec <petr-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
> ---
>  drivers/char/tpm/tpm_acpi.c | 70 ++++++++++++++++++++++++++++-----------------
>  1 file changed, 43 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_acpi.c b/drivers/char/tpm/tpm_acpi.c
> index 169edf3ce86d..e48b1503220c 100644
> --- a/drivers/char/tpm/tpm_acpi.c
> +++ b/drivers/char/tpm/tpm_acpi.c
> @@ -48,46 +48,62 @@ struct acpi_tcpa {
>  /* read binary bios log */
>  int tpm_read_log_acpi(struct tpm_chip *chip)
>  {
> -	struct acpi_tcpa *buff;
>  	acpi_status status;
>  	void __iomem *virt;
>  	u64 len, start;
>  	struct tpm_bios_log *log;
>  
> -	if (chip->flags & TPM_CHIP_FLAG_TPM2)
> -		return -ENODEV;
> -
> -	log = &chip->log;
> -
>  	/* Unfortuntely ACPI does not associate the event log with a specific
>  	 * TPM, like PPI. Thus all ACPI TPMs will read the same log.
>  	 */
>  	if (!chip->acpi_dev_handle)
>  		return -ENODEV;
>  
> -	/* Find TCPA entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
> -	status = acpi_get_table(ACPI_SIG_TCPA, 1,
> -				(struct acpi_table_header **)&buff);
> -
> -	if (ACPI_FAILURE(status))
> -		return -ENODEV;
> -
> -	switch(buff->platform_class) {
> -	case BIOS_SERVER:
> -		len = buff->server.log_max_len;
> -		start = buff->server.log_start_addr;
> -		break;
> -	case BIOS_CLIENT:
> -	default:
> -		len = buff->client.log_max_len;
> -		start = buff->client.log_start_addr;
> -		break;
> -	}
> -	if (!len) {
> -		dev_warn(&chip->dev, "%s: TCPA log area empty\n", __func__);
> -		return -EIO;
> +	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
> +		struct acpi_table_tpm2 *buff;
> +
> +		/* Find TPM2 entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
> +		status = acpi_get_table(ACPI_SIG_TPM2, 1,
> +					(struct acpi_table_header **)&buff);
> +
> +		if (ACPI_FAILURE(status) || buff->header.length < ACPI_TPM2_SIZE_WITH_LOG)
> +			return -ENODEV;
> +
> +		len = buff->minimum_log_length;
> +		start = buff->log_address;
> +		if (!len) {
> +			dev_warn(&chip->dev, "%s: TPM2 log area empty\n", __func__);
> +			return -EIO;
> +		}
> +	} else {
> +		struct acpi_tcpa *buff;
> +
> +		/* Find TCPA entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
> +		status = acpi_get_table(ACPI_SIG_TCPA, 1,
> +					(struct acpi_table_header **)&buff);
> +
> +		if (ACPI_FAILURE(status))
> +			return -ENODEV;
> +
> +		switch(buff->platform_class) {
> +		case BIOS_SERVER:
> +			len = buff->server.log_max_len;
> +			start = buff->server.log_start_addr;
> +			break;
> +		case BIOS_CLIENT:
> +		default:
> +			len = buff->client.log_max_len;
> +			start = buff->client.log_start_addr;
> +			break;
> +		}
> +		if (!len) {
> +			dev_warn(&chip->dev, "%s: TCPA log area empty\n", __func__);
> +			return -EIO;
> +		}
>  	}
>  
> +	log = &chip->log;
> +
>  	/* malloc EventLog space */
>  	log->bios_event_log = kmalloc(len, GFP_KERNEL);
>  	if (!log->bios_event_log)
> -- 
> 2.11.0
> 

It would be a better idea to rename the existing function as
tpm1_read_log_acpi() and add a new function called
tpm2_read_log_acpi().

/Jarkko

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