linux-kernel - Re: [PATCH v6 1/2] tpm: enhance read_log_of() to support Physical TPM event log

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Message-ID: <20161126161522.umra77n3yqbpwn5u@intel.com>
Date:   Sat, 26 Nov 2016 18:15:22 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Nayna Jain <nayna@...ux.vnet.ibm.com>
Cc:     tpmdd-devel@...ts.sourceforge.net, peterhuewe@....de,
        tpmdd@...horst.net, jgunthorpe@...idianresearch.com,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 1/2] tpm: enhance read_log_of() to support Physical
 TPM event log

On Sat, Nov 26, 2016 at 07:45:38AM -0500, Nayna Jain wrote:
> Physical TPMs use Open Firmware Device Tree bindings that are similar
> to the IBM Power virtual TPM to support event log. However, these
> properties store the values in different endianness for Physical
> and Virtual TPM.
> 
> This patch fixes the endianness issue by doing appropriate conversion
> based on Physical or Virtual TPM.
> 
> Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
> ---
>  drivers/char/tpm/tpm_of.c | 27 +++++++++++++++++++++++----
>  1 file changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_of.c b/drivers/char/tpm/tpm_of.c
> index 7dee42d7..4b0d5e6 100644
> --- a/drivers/char/tpm/tpm_of.c
> +++ b/drivers/char/tpm/tpm_of.c
> @@ -27,6 +27,8 @@ int tpm_read_log_of(struct tpm_chip *chip)
>  	const u32 *sizep;
>  	const u64 *basep;
>  	struct tpm_bios_log *log;
> +	u32 log_size;
> +	u64 log_base;

Maybe just base and size?

>  
>  	log = &chip->log;
>  	if (chip->dev.parent && chip->dev.parent->of_node)
> @@ -41,18 +43,35 @@ int tpm_read_log_of(struct tpm_chip *chip)
>  	if (sizep == NULL || basep == NULL)
>  		return -EIO;
>  
> -	if (*sizep == 0) {
> +	/*
> +	 * For both vtpm/tpm, firmware has log addr and log size in big
> +	 * endian format. But in case of vtpm, there is a method called
> +	 * sml-handover which is run during kernel init even before
> +	 * device tree is setup. This sml-handover function takes care
> +	 * of endianness and writes to sml-base and sml-size in little
> +	 * endian format. For this reason, vtpm doesn't need conversion
> +	 * but physical tpm needs the conversion.
> +	 */
> +	if (of_property_match_string(np, "compatible", "IBM,vtpm") < 0) {
> +		log_size = be32_to_cpup(sizep);
> +		log_base = be64_to_cpup(basep);
> +	} else {
> +		log_size = *sizep;
> +		log_base = *basep;
> +	}
> +
> +	if (log_size == 0) {
>  		dev_warn(&chip->dev, "%s: Event log area empty\n", __func__);
>  		return -EIO;
>  	}
>  
> -	log->bios_event_log = kmalloc(*sizep, GFP_KERNEL);
> +	log->bios_event_log = kmalloc(log_size, GFP_KERNEL);
>  	if (!log->bios_event_log)
>  		return -ENOMEM;
>  
> -	log->bios_event_log_end = log->bios_event_log + *sizep;
> +	log->bios_event_log_end = log->bios_event_log + log_size;
>  
> -	memcpy(log->bios_event_log, __va(*basep), *sizep);
> +	memcpy(chip->log.bios_event_log, __va(log_base), log_size);

Why did you change the first parameter?

>  
>  	return 0;
>  }
> -- 
> 2.5.0
> 

/Jarkko