Re: [PATCH v2 5/5] test: Add sandbox TPM boot measurement

Eddie James
2023-01-11T14:14:55Z

On 1/10/23 16:37, Heinrich Schuchardt wrote:
> On 1/10/23 23:32, Heinrich Schuchardt wrote:
>> On 1/9/23 22:55, Eddie James wrote:
>>> Use the sandbox TPM driver to measure some boot images in a unit
>>> test case.
>>>
>>> $ ./u-boot -T -c "ut measurement"
>>> Running 1 measurement tests
>>> Test: measure: measurement.c
>>> Failures: 0
>>>
>>> Signed-off-by: Eddie James <eajames@linux.ibm.com>
>>> ---
>>>   arch/sandbox/dts/test.dts | 12 +++++++
>>>   configs/sandbox_defconfig |  1 +
>>>   include/test/suites.h     |  1 +
>>>   test/boot/Makefile        |  1 +
>>>   test/boot/measurement.c   | 66
>>> +++++++++++++++++++++++++++++++++++++++
>>>   test/cmd_ut.c             |  2 ++
>>>   6 files changed, 83 insertions(+)
>>>   create mode 100644 test/boot/measurement.c
>>>
>>> diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
>>> index dffe10adbf..ad90bf0541 100644
>>> --- a/arch/sandbox/dts/test.dts
>>> +++ b/arch/sandbox/dts/test.dts
>>> @@ -66,6 +66,17 @@
>>>           osd0 = "/osd";
>>>       };
>>>
>>> +    reserved-memory {
>>> +        #address-cells = <1>;
>>> +        #size-cells = <1>;
>>> +        ranges;
>>> +
>>> +        event_log: tcg_event_log@d0e000 {
>>> +            no-map;
>>
>> Isn't no-map misplaced? Shouldn't it be a reserved-memory property?
>
> The placement is correct. But I still wonder why we should have this
> area as no-map.
>
>>
>> If the memory region is not mapped, Linux can never access it as
>> described in
>> Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml.

I read the documentation as meaning that Linux won't map it as part of
it's standard mappings. It's still available for a device driver (TPM
driver in this case). I believe no-map is appropriate here since we
don't want anything except the TPM driver to access that memory.

Thanks,

Eddie

>>
>> Please, document all changes to the device-tree semantics via patches
>> for the Linux kernels documentation and provide a full example.
>>
>> Best regards
>>
>> Heinrich
>