Please ignore that last comment – I see that patches have been merged recently that make it irrelevant.

Chris

From: Chris.Brand--- via TF-M <tf-m@lists.trustedfirmware.org>
Sent: September 8, 2022 8:18 AM
To: tf-m@lists.trustedfirmware.org
Subject: [TF-M] Re: Status of RSS platform?

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Thanks, everyone. This is all very helpful.

I see that docs/platform/arm/rss/readme.rst just refers to the generic build instructions. I wonder if it might make sense to add a note about the tf-m-extras repo there?

Chris

From: Jamie Fox via TF-M <tf-m@lists.trustedfirmware.org>
Sent: September 7, 2022 10:29 AM
To: Brand Chris (CSCA CSS ICW SW PSW 1) <Chris.Brand@infineon.com>; tf-m@lists.trustedfirmware.org
Cc: Maulik Patel <Maulik.Patel@arm.com>
Subject: [TF-M] Re: Status of RSS platform?

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Hi Chris,

> I was curious about the implementation of tfm_hal_get_mem_security_attr(), tfm_hal_get_secure_access_attr() and tfm_hal_get_ns_access_attr() on an ARMv8 multi-core platform, but there doesn't currently seem to be an implementation of those HAL functions.

Currently RSS only receives messages from other processors that are serialized and sent in-band over the MHUs, so no pointers to check in this case. The only mem checks are within the RSS core, which are the same as other Armv8-M platforms (see platform/ext/target/arm/rss/tfm_hal_isolation.c).

But… we will add support for MHU messages containing pointers to shared memory in the other processors, but I think even then the current multi-core mem checks in tfm_multi_core_mem_check.c are not a good fit for us, because:

It manually checks MPU regions, which isn’t necessary on Armv8-M where we have the TT instruction for that.
The pointers RSS receives over the MHU are 64-bit addresses, which will be dynamically mapped into regions in RSS’s 32-bit memory map. By the time SPM calls the mem check, it only has the 32-bit address, which isn’t useful for checking access rights to the original address.
RSS can receive messages from multiple other endpoints each with their own MHU, so which addresses are permitted depends on which MHU the message was received. Again, this information is not available at the point the SPM makes the mem check, it’s not enough to know the message came from “NS” because there’s more than one “NS”.

I think 1 is easily solved by abstracting the arch from the multi-core implementation, and relevant for any Armv8-M multi-core platform. For 2 and 3, they are quite RSS-specific problems and, though it should be possible to recover the original address and sender inside the RSS implementation of the HAL, it would all be a bit circuitous. I think for us it makes more sense to check memory permissions in the MHU receiver code, at the point the address is extracted from the MHU message and before the SPM is called. See here for relevant patch in progress: https://review.trustedfirmware.org/c/TF-M/trusted-firmware-m/+/15949

Kind regards,

Jamie

From: Maulik Patel via TF-M <tf-m@lists.trustedfirmware.org>
Sent: 07 September 2022 09:46
To: tf-m@lists.trustedfirmware.org; Chris.Brand@infineon.com
Subject: [TF-M] Re: Status of RSS platform?

Hi Chris,

RSS build requires new runtime Measured Boot Service. This service partition is not yet part of PSA specification and hence it resides in the tf-m-extras repository. (https://git.trustedfirmware.org/TF-M/tf-m-extras.git/)

For out of tree partition build, if you map the tf-m-extras repo and provideTFM_EXTRA_MANIFEST_LIST_FILES =<path_to_measured_boot_manifest_list.yaml> and TFM_EXTRA_PARTITION_PATHS=<path_to_measured_boot_partition> (example as below), then it should fix build issue.

-DTFM_EXTRA_MANIFEST_LIST_FILES=../../tf-m-extras/partitions/measured_boot/measured_boot_manifest_list.yaml
-DTFM_EXTRA_PARTITION_PATHS=../../tf-m-extras/partitions/measured_boot

If the error persists, could you please send me the build options you are using and I'll look into this further.

Best Regards,

Maulik

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Subject: TF-M Digest, Vol 47, Issue 7

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Today's Topics:

   1. Status of RSS platform? (Chris.Brand@infineon.com)

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Message: 1
Date: Tue, 6 Sep 2022 21:48:05 +0000
From: <Chris.Brand@infineon.com>
Subject: [TF-M] Status of RSS platform?
To: <tf-m@lists.trustedfirmware.org>
Message-ID: <2441d128df93483abc1da39c38e89885@infineon.com>
Content-Type: multipart/alternative;
        boundary="_000_2441d128df93483abc1da39c38e89885infineoncom_"

Hi,

I'm wondering what the status of the RSS platform is. I tried to build it from the current HEAD of master and also from a few earlier commits, and cannot get it to build (I get an error about TFM_MEASURED_BOOT_SID being undeclared in some of the generated code).

I was curious about the implementation of tfm_hal_get_mem_security_attr(), tfm_hal_get_secure_access_attr() and tfm_hal_get_ns_access_attr() on an ARMv8 multi-core platform, but there doesn't currently seem to be an implementation of those HAL functions.

Thanks,

Chris Brand

Cypress Semiconductor (Canada), Inc.
An Infineon Technologies Company
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CSCA CSS ICW SW PSW 1
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