On Mon, Mar 11, 2019 at 01:43:19PM +0000, Tamas Ban via TF-M wrote:
>https://developer.trustedfirmware.org/w/tf_m/design/trusted_boot/rollback_p…
Oh, and a little terminology comment about the Trusted non-volatile
(NV) counters. This section should use "increase" and "decrease" not
"increment" and "decrement". There is no requirement that the counter
only be incremented (having 1 added to the value), only that it be set
to a larger value than the current value.
You should probably also add a discussion as to how testing will be
done with a HW security counter.
Again, my suggestion is to not add an additional counter, but just use
the existing version field (minus the build number) as the security
counter value.
David
Hi Alan,
I can answer this from the PSA Firmware Framework specification point of view, Ken (or others in the TF-M team) can clarify how closely the TF-M behaviour matches this.
In the manifest each service has a "signal" attribute which is a C identifier that is given the signal value for that service. The value is allocated by the TF-M tools and should be available to the SP source code via a generated header file - the specification places these definitions in the psa_manifest/<manifestfilename>.h header file, matching the name of the manifest file itself.
When the SP receives a set of signals from psa_wait(), it can identify which signals are asserted using these identifiers to test the signal bits.
The example RoT Service in Appendix D of the PSA Firmware Framework demonstrates this.
Regards,
Andrew
-----Original Message-----
From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> On Behalf Of DeMars, Alan via TF-M
Sent: 08 March 2019 13:52
To: tf-m(a)lists.trustedfirmware.org
Subject: [TF-M] multiple services within the same SP
In a multi-service SP, how does the SP know which SID has been used to connect to it?
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Hi Alan,
Services are listed in SP. SPM could enumerate the services in a SP by the list.
You can check the member variable ' service_list' of ' tfm_spm_ipc_partition_t' to know details.
-Ken
> -----Original Message-----
> From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> On Behalf Of DeMars,
> Alan via TF-M
> Sent: Friday, March 8, 2019 9:52 PM
> To: tf-m(a)lists.trustedfirmware.org
> Subject: [TF-M] multiple services within the same SP
>
> In a multi-service SP, how does the SP know which SID has been used to connect
> to it?
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