linux-kernel - Re: [PATCH v7 1/2] tpm: enhance read_log_of() to support Physical TPM event log

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Message-Id: <5854161D.6010006@linux.vnet.ibm.com>
Date:   Fri, 16 Dec 2016 21:58:13 +0530
From:   Nayna <nayna@...ux.vnet.ibm.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.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 v7 1/2] tpm: enhance read_log_of() to support Physical TPM
 event log



On 12/12/2016 08:10 PM, Jarkko Sakkinen wrote:
> On Sun, Dec 11, 2016 at 12:35:32AM -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.
>
> Will other device tree using firmwares than OF use the same bindings?

Yes, that is what expected that all other device tree using firmware 
will also use same bindings.

Thanks & Regards,
     - Nayna

>
>> 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..de57d4a 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 size;
>> +	u64 base;
>>
>>   	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) {
>> +		size = be32_to_cpup(sizep);
>> +		base = be64_to_cpup(basep);
>> +	} else {
>> +		size = *sizep;
>> +		base = *basep;
>> +	}
>> +
>> +	if (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(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 + size;
>>
>> -	memcpy(log->bios_event_log, __va(*basep), *sizep);
>> +	memcpy(log->bios_event_log, __va(base), size);
>>
>>   	return 0;
>>   }
>> --
>> 2.5.0
>>
>
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
>
> /Jarkko
>