June 2020 - TF-M - lists.trustedfirmware.org

Invitation: TF-M Tech Forum (US TZ) @ Thu 25 Jun 2020 16:00 - 17:00 (BST) (tf-m@lists.trustedfirmware.org)

by Bill Fletcher

You have been invited to the following event. Title: TF-M Tech Forum (US TZ) ** 25th June call rescheduled (due to holidays in China) **About TF-M Tech forum:This is an open forum for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.Feel free to forward it to colleagues.Details of previous meetings are here: https://www.trustedfirmware.org/meetings/tf-m-technical-forum/Tr… Firmware is inviting you to a scheduled Zoom meeting.Join Zoom Meetinghttps://zoom.us/j/9159704974Meeting ID: 915 970 4974One tap mobile+16465588656,,9159704974# US (New York)+16699009128,,9159704974# US (San Jose)Dial by your location        +1 646 558 8656 US (New York)        +1 669 900 9128 US (San Jose)        877 853 5247 US Toll-free        888 788 0099 US Toll-freeMeeting ID: 915 970 4974Find your local number: https://zoom.us/u/ad27hc6t7h   When: Thu 25 Jun 2020 16:00 – 17:00 United Kingdom Time Where: Via Zoom Calendar: tf-m(a)lists.trustedfirmware.org Who: * Bill Fletcher- creator * tf-m(a)lists.trustedfirmware.org Event details: https://www.google.com/calendar/event?action=VIEW&eid=MGFmdnVlcmltYjB1M2Y1O… Invitation from Google Calendar: https://www.google.com/calendar/ You are receiving this courtesy email at the account tf-m(a)lists.trustedfirmware.org because you are an attendee of this event. To stop receiving future updates for this event, decline this event. Alternatively, you can sign up for a Google Account at https://www.google.com/calendar/ and control your notification settings for your entire calendar. Forwarding this invitation could allow any recipient to send a response to the organiser and be added to the guest list, invite others regardless of their own invitation status or to modify your RSVP. Learn more at https://support.google.com/calendar/answer/37135#forwarding

4 years, 6 months

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Cancelled event with note: TF-M tech Forum (Asia TZ) @ Thu 25 Jun 2020 07:00 - 08:00 (BST) (tf-m@lists.trustedfirmware.org)

by Bill Fletcher

This event has been cancelled with this note: "Due to holidays in China, the event in this time slot is cancelled. " Title: TF-M tech Forum (Asia TZ) About TF-M Tech forum:This is an open forum for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.Feel free to forward it to colleagues.Details of previous meetings are here: https://www.trustedfirmware.org/meetings/tf-m-technical-forum/Tr… Firmware is inviting you to a scheduled Zoom meeting.Join Zoom Meetinghttps://zoom.us/j/9159704974Meeting ID: 915 970 4974One tap mobile+16465588656,,9159704974# US (New York)+16699009128,,9159704974# US (San Jose)Dial by your location        +1 646 558 8656 US (New York)        +1 669 900 9128 US (San Jose)        877 853 5247 US Toll-free        888 788 0099 US Toll-freeMeeting ID: 915 970 4974Find your local number: https://zoom.us/u/ad27hc6t7h   When: Thu 25 Jun 2020 07:00 – 08:00 United Kingdom Time Calendar: tf-m(a)lists.trustedfirmware.org Who: * Bill Fletcher- creator * tf-m(a)lists.trustedfirmware.org Invitation from Google Calendar: https://www.google.com/calendar/ You are receiving this courtesy email at the account tf-m(a)lists.trustedfirmware.org because you are an attendee of this event. To stop receiving future updates for this event, decline this event. Alternatively, you can sign up for a Google Account at https://www.google.com/calendar/ and control your notification settings for your entire calendar. Forwarding this invitation could allow any recipient to send a response to the organiser and be added to the guest list, invite others regardless of their own invitation status or to modify your RSVP. Learn more at https://support.google.com/calendar/answer/37135#forwarding

4 years, 6 months

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Re: [TF-M] TF-M PSA key management

by Soby Mathew

Hi Brian, The struct you have mentioned is part of the implementation defined `psa_key_attributes_t` data structure. The key algorithm and policy are accessed via appropriate get/set API's (like psa_set_key_algorithm/ psa_get_key_algorithm). Hence these fields are not meant to be directly accessed by the clients but are an implementation detail of crypto Service. The only reason the 2 algorithm fields exists now is because the mbedcrypto defined the structure that way. I have a patch in flight which cleans up the client view of the psa_key_attributes_t such that only fields required by client are defined. The patch is available for review here : https://review.trustedfirmware.org/c/trusted-firmware-m/+/4217 Regarding psa_open_key() and psa_close_key(), TF-M tries to implement PSA Crypto 1.0 Beta 3 version of the spec whereas the APIs are removed in 1.0 version. Currently mbedcrypto does not support 1.0 version fully yet. Once 1.0 is supported mbedcrypto, then TF-M will also make the migrate the APIs to 1.0. This is expected to happen during Q3 timeframe. Best Regards Soby Mathew From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> On Behalf Of Quach, Brian via TF-M Sent: 02 June 2020 23:44 To: tf-m(a)lists.trustedfirmware.org Subject: [TF-M] TF-M PSA key management Hi All, I see that the PSA crypto API v1.0 spec says "This specification only defines policies that restrict keys to a single algorithm, which is consistent with both common practice and security good practice. ", but the TF-M code defines two algs in the policy struct. Which will be the path going forward? struct psa_key_policy_s { psa_key_usage_t usage; psa_algorithm_t alg; psa_algorithm_t alg2; }; I also see psa_open_key() and psa_close_key() were removed from the spec. Any plans to remove from TF-M code in the future? Regards, Brian Quach SimpleLink MCU Texas Instruments Inc. 12500 TI Blvd, MS F-4000 Dallas, TX 75243 214-479-4076

4 years, 6 months

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Re: [TF-M] Changes required to enable Zephyr integration as External_Project

by Anton Komlev

Hi, There was a plan to include the new build system into TFM v1.1 but looking onto change size and interdependencies with other ongoing changes like code restructuring, the delivery of new CMake in TFM v1.1 is optional. The intention is to be safe and test more instead of delivery ahead and fix later. Anton -----Original Message----- From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> On Behalf Of Kumar Gala via TF-M Sent: 02 June 2020 13:50 To: Raef Coles <Raef.Coles(a)arm.com> Cc: tf-m(a)lists.trustedfirmware.org Subject: Re: [TF-M] Changes required to enable Zephyr integration as External_Project What’s the timeframe expectation with the new cmake work? Is this something that is planned for TFM 1.1? - k > On Jun 2, 2020, at 7:11 AM, Raef Coles via TF-M <tf-m(a)lists.trustedfirmware.org> wrote: > > Hi, > > Thank you very much for the changes to the image signing script - those look like great QOL improvements. > > WRT Ninja and externalproject support, there is currently an ongoing effort to improve the TF-M build system by rewriting it to use more modern and streamlined cmake. I haven't tested it as an externalproject yet, but am pretty confident that it should now work "out of the box". When it gets to the stage that it can be submitted to trustedfirmware.org as a patch I'll try to reply to this so you can test that. > > I personally hadn't used Ninja much, but am pleasantly surprised with how fast it is. I will do my best to make sure that the new cmake also works with ninja, since support should be relatively simple. > > Raef > > ________________________________________ > From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> on behalf of Kevin > Townsend via TF-M <tf-m(a)lists.trustedfirmware.org> > Sent: 02 June 2020 12:11 > To: Thomas Törnblom via TF-M > Subject: [TF-M] Changes required to enable Zephyr integration as > External_Project > > Hi, > > The following task lists some of the changes that we had to make to > enable TF-M to be built using ExternalProject_Add from Zephyr, as well > as enabling the use of ninja for TF-M builds (which is often > significantly faster than using classic > makefiles): https://developer.trustedfirmware.org/T760 > > The ninja changes have been tested with: > > $ cmake -GNinja -DPROJ_CONFIG=`readlink -f ../configs/ConfigDefault.cmake` -DTARGET_PLATFORM=LPC55S69 -DBL2=False -DCOMPILER=GNUARM .. > $ ninja > > The changes to imgtool.py resolve some platform issues when signing binaries, and add a convenience requirements.txt file that can be run in CI to ensure that all of the Python dependencies are met for this tool. > > Any concerns or feedback on these are welcome, but I would be > interested to hear any opinions on ninja which is often considerably > faster out of the box when compiling (at least on Linux and native OS X, which is what I use for my builds). > > Best regards, > Kevin > -- > TF-M mailing list > TF-M(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-m -- TF-M mailing list TF-M(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-m

4 years, 6 months

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TF-M PSA key management

by Quach, Brian

Hi All, I see that the PSA crypto API v1.0 spec says "This specification only defines policies that restrict keys to a single algorithm, which is consistent with both common practice and security good practice. ", but the TF-M code defines two algs in the policy struct. Which will be the path going forward? struct psa_key_policy_s { psa_key_usage_t usage; psa_algorithm_t alg; psa_algorithm_t alg2; }; I also see psa_open_key() and psa_close_key() were removed from the spec. Any plans to remove from TF-M code in the future? Regards, Brian Quach SimpleLink MCU Texas Instruments Inc. 12500 TI Blvd, MS F-4000 Dallas, TX 75243 214-479-4076

4 years, 6 months

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Re: [TF-M] DSP instructions and FPU use

by Joseph Yiu

Hi Ken, Soby, In additional to FPCCR_S.TS, You should also set FPCCR_S.CLRONRET and FPCCR_S.CLRONRETS. FPCCR_S.CLRONRET ensures that FPU register contents are cleared when return from a Secure exception to the Non-secure world, and FPCCR_S.CLRONRETS ensures that the Non-secure world cannot change the FPCCR_S.CLRONRET setting. Regards, Joseph From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> On Behalf Of Soby Mathew via TF-M Sent: 02 June 2020 04:36 To: Ken Liu <Ken.Liu(a)arm.com>; TF-M mailing list <tf-m(a)lists.trustedfirmware.org> Cc: nd <nd(a)arm.com> Subject: Re: [TF-M] DSP instructions and FPU use Hi Ken, I agree that FPCCR_S.TS (in addition to other setting for FP) should be set if FPU needs to be used in secure world. The FPCCR.LSPEN allows saving the context lazily which was what I was referring to previously. Eventhough the hardware is performing the stacking, the policy chosen (lazy stacking/stack always) affects interrupt latency which should be considered for the design for FPU usage in TF-M. Best Regards Soby Mathew From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org<mailto:tf-m-bounces@lists.trustedfirmware.org>> On Behalf Of Ken Liu via TF-M Sent: 01 June 2020 15:55 To: tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org> Cc: nd <nd(a)arm.com<mailto:nd@arm.com>> Subject: Re: [TF-M] DSP instructions and FPU use Hi Soby & Andrej, The FP context is managed by hardware automatically in M-profile architecture. While booting we clear FPCA since we are not using FP under handler mode, we don't want FP get involved during initialization and need extra clean up job. But if a thread uses FP the FPCA is set to 1 automatically, and if exceptions are happening the FP context stacked automatically by hardware - the secure scheduler just keep the EXC_RETURN which contains FP context and finally recover it back. Which means if you enabled hardware FP unintentional it can work, the only place a problem may occur should be the non-secure preempting secure execution case. I think the only thing we are missing now is we did not set FPCCR_S.TS = 1 since we did not realize that user would enable FP in secure world. This would cause the FP register may contain secure information while Non-secure preempting secure execution. Need to go through the settings and double-check. So at least before we finish the estimation I think FPCCR_S.TS should be set to ensure the security. Andrej, have you set this bit while you are using hardware FP? Or just let it go (use default TF-M setting)? Thanks. /Ken From: Soby Mathew <Soby.Mathew(a)arm.com<mailto:Soby.Mathew@arm.com>> Sent: Monday, June 1, 2020 5:25 PM To: Ken Liu <Ken.Liu(a)arm.com<mailto:Ken.Liu@arm.com>>; tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org> Cc: nd <nd(a)arm.com<mailto:nd@arm.com>> Subject: RE: DSP instructions and FPU use Hi, For enabling floating point the ARMv8-M architecture allows the flowing possibilities : * Stacking the basic Floating-point context. * Stacking the basic Floating-point context and the additional Floating-point context. * Activation of Lazy Floating-point state preservation. The easiest way would be to enable FP context stacking for every context switch but it would impact every context switch irrespective of whether FP unit is used in that context or not . I guess this is the approach taken by Andrej ? . The Lazy Floating point state preservation would be better for performance but it would have additional complexity in managing the contexts. Just blue sky thinking here: There could be a middle ground wherein some partitions are allowed to use FP while others are not because they don't really need to. The ones allowed to use FP will need to cater for the additional stack requirement to save FP context. The actual save of the context can be done either on context switch to the partition or lazily. This approach could give the benefit of both performance and memory savings but it requires some analysis and design to be done in TF-M. Best Regards Soby Mathew From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org<mailto:tf-m-bounces@lists.trustedfirmware.org>> On Behalf Of Ken Liu via TF-M Sent: 01 June 2020 09:05 To: tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org> Cc: nd <nd(a)arm.com<mailto:nd@arm.com>> Subject: Re: [TF-M] DSP instructions and FPU use Hi Andrej, You mean the hardware floatpoint can be used in the Secure Partition? That's a good information, can you share us the compiler flags about float-point you are using? Thanks. /Ken From: Andrej Butok <andrey.butok(a)nxp.com<mailto:andrey.butok@nxp.com>> Sent: Monday, June 1, 2020 2:46 PM To: Ken Liu <Ken.Liu(a)arm.com<mailto:Ken.Liu@arm.com>> Cc: tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org> Subject: RE: DSP instructions and FPU use FYI: >> Can you do some experiments on enabling hardware float point and see if it is working In our SDK, the LPC55S HW Float point is enabled for all TFM projects (Kel, GCC/MCUx), and it works. From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org<mailto:tf-m-bounces@lists.trustedfirmware.org>> On Behalf Of Ken Liu via TF-M Sent: Monday, June 1, 2020 8:41 AM To: tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org> Cc: nd <nd(a)arm.com<mailto:nd@arm.com>> Subject: Re: [TF-M] DSP instructions and FPU use Hi Cindy, The reason is we need to estimate the potential security risks after enabling hardware floating-point, so it is set as software FPU as default. Can you do some experiments on enabling hardware float point and see if it is working, and then let's see the patch? That would be helpful for our estimation. During bootup, we cleared the CONTROL.FPCA, and if you access hardware float point in a partition thread should work because it would re-invoke the FPCA bit and make everything work as usual. But as I mentioned, we need to estimate it and give a proper solution and then enable your patch. For DSP, a similar reason is there, we need to take an estimation. But in theory, you can enable the things you have on the hardware, just be caution that the shared resources between S/NS can be the risk (and the resource sharing caused - co-work problem, the context save/load). Thanks. /Ken From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org<mailto:tf-m-bounces@lists.trustedfirmware.org>> On Behalf Of Cindy Chaumont via TF-M Sent: Friday, May 29, 2020 6:39 PM To: tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org> Subject: [TF-M] DSP instructions and FPU use Hello, I am using the GNUARM compiler and LPCXpresso55S69-EVK dev board and I would like to use DSP instructions and FPU (in secure image). About FPU, it seems there is no way to use the hardware floating-point support instead of the software support (see "-msoft-float" flag in CommonConfig.cmake file). Is there a reason for that? Maybe some performance reasons? About DSP, in CompilerGNUARMxy.cmake files, architecture definition is preferred to CPU type and, in my case, "-march=armv8-m.main" flags is chosen (without +dsp option). The solution I found is to only define ARM_CPU_TYPE (and not ARM_CPU_ARCHITECTURE) to use "-mcpu=cortex-m33" flag instead of "-march=armv8-m.main". So I can use DSP instructions. However, I am not sure if this is the best solution. Maybe an option could be added to allow or not the use of DSP instructions? Thank you in advance for the answer, Best regards, Cindy

4 years, 6 months

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Re: [TF-M] Changes required to enable Zephyr integration as External_Project

by Kumar Gala

What’s the timeframe expectation with the new cmake work? Is this something that is planned for TFM 1.1? - k > On Jun 2, 2020, at 7:11 AM, Raef Coles via TF-M <tf-m(a)lists.trustedfirmware.org> wrote: > > Hi, > > Thank you very much for the changes to the image signing script - those look like great QOL improvements. > > WRT Ninja and externalproject support, there is currently an ongoing effort to improve the TF-M build system by rewriting it to use more modern and streamlined cmake. I haven't tested it as an externalproject yet, but am pretty confident that it should now work "out of the box". When it gets to the stage that it can be submitted to trustedfirmware.org as a patch I'll try to reply to this so you can test that. > > I personally hadn't used Ninja much, but am pleasantly surprised with how fast it is. I will do my best to make sure that the new cmake also works with ninja, since support should be relatively simple. > > Raef > > ________________________________________ > From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> on behalf of Kevin Townsend via TF-M <tf-m(a)lists.trustedfirmware.org> > Sent: 02 June 2020 12:11 > To: Thomas Törnblom via TF-M > Subject: [TF-M] Changes required to enable Zephyr integration as External_Project > > Hi, > > The following task lists some of the changes that we had to make to enable > TF-M to be built using ExternalProject_Add from Zephyr, as well as enabling the > use of ninja for TF-M builds (which is often significantly faster than using classic > makefiles): https://developer.trustedfirmware.org/T760 > > The ninja changes have been tested with: > > $ cmake -GNinja -DPROJ_CONFIG=`readlink -f ../configs/ConfigDefault.cmake` -DTARGET_PLATFORM=LPC55S69 -DBL2=False -DCOMPILER=GNUARM .. > $ ninja > > The changes to imgtool.py resolve some platform issues when signing binaries, and add a convenience requirements.txt file that can be run in CI to ensure that all of the Python dependencies are met for this tool. > > Any concerns or feedback on these are welcome, but I would be interested to hear > any opinions on ninja which is often considerably faster out of the box when compiling > (at least on Linux and native OS X, which is what I use for my builds). > > Best regards, > Kevin > -- > TF-M mailing list > TF-M(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-m

4 years, 6 months

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Re: [TF-M] Changes required to enable Zephyr integration as External_Project

by Raef Coles

Hi, Thank you very much for the changes to the image signing script - those look like great QOL improvements. WRT Ninja and externalproject support, there is currently an ongoing effort to improve the TF-M build system by rewriting it to use more modern and streamlined cmake. I haven't tested it as an externalproject yet, but am pretty confident that it should now work "out of the box". When it gets to the stage that it can be submitted to trustedfirmware.org as a patch I'll try to reply to this so you can test that. I personally hadn't used Ninja much, but am pleasantly surprised with how fast it is. I will do my best to make sure that the new cmake also works with ninja, since support should be relatively simple. Raef ________________________________________ From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> on behalf of Kevin Townsend via TF-M <tf-m(a)lists.trustedfirmware.org> Sent: 02 June 2020 12:11 To: Thomas Törnblom via TF-M Subject: [TF-M] Changes required to enable Zephyr integration as External_Project Hi, The following task lists some of the changes that we had to make to enable TF-M to be built using ExternalProject_Add from Zephyr, as well as enabling the use of ninja for TF-M builds (which is often significantly faster than using classic makefiles): https://developer.trustedfirmware.org/T760 The ninja changes have been tested with: $ cmake -GNinja -DPROJ_CONFIG=`readlink -f ../configs/ConfigDefault.cmake` -DTARGET_PLATFORM=LPC55S69 -DBL2=False -DCOMPILER=GNUARM .. $ ninja The changes to imgtool.py resolve some platform issues when signing binaries, and add a convenience requirements.txt file that can be run in CI to ensure that all of the Python dependencies are met for this tool. Any concerns or feedback on these are welcome, but I would be interested to hear any opinions on ninja which is often considerably faster out of the box when compiling (at least on Linux and native OS X, which is what I use for my builds). Best regards, Kevin

4 years, 6 months

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Changes required to enable Zephyr integration as External_Project

by Kevin Townsend

Hi, The following task lists some of the changes that we had to make to enable TF-M to be built using ExternalProject_Add from Zephyr, as well as enabling the use of ninja for TF-M builds (which is often significantly faster than using classic makefiles): https://developer.trustedfirmware.org/T760 The ninja changes have been tested with: $ cmake -GNinja -DPROJ_CONFIG=`readlink -f ../configs/ConfigDefault.cmake` -DTARGET_PLATFORM=LPC55S69 -DBL2=False -DCOMPILER=GNUARM .. $ ninja The changes to imgtool.py resolve some platform issues when signing binaries, and add a convenience requirements.txt file that can be run in CI to ensure that all of the Python dependencies are met for this tool. Any concerns or feedback on these are welcome, but I would be interested to hear any opinions on ninja which is often considerably faster out of the box when compiling (at least on Linux and native OS X, which is what I use for my builds). Best regards, Kevin

4 years, 6 months

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Re: [TF-M] DSP instructions and FPU use

by Soby Mathew

Hi Ken, I agree that FPCCR_S.TS (in addition to other setting for FP) should be set if FPU needs to be used in secure world. The FPCCR.LSPEN allows saving the context lazily which was what I was referring to previously. Eventhough the hardware is performing the stacking, the policy chosen (lazy stacking/stack always) affects interrupt latency which should be considered for the design for FPU usage in TF-M. Best Regards Soby Mathew From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> On Behalf Of Ken Liu via TF-M Sent: 01 June 2020 15:55 To: tf-m(a)lists.trustedfirmware.org Cc: nd <nd(a)arm.com> Subject: Re: [TF-M] DSP instructions and FPU use Hi Soby & Andrej, The FP context is managed by hardware automatically in M-profile architecture. While booting we clear FPCA since we are not using FP under handler mode, we don't want FP get involved during initialization and need extra clean up job. But if a thread uses FP the FPCA is set to 1 automatically, and if exceptions are happening the FP context stacked automatically by hardware - the secure scheduler just keep the EXC_RETURN which contains FP context and finally recover it back. Which means if you enabled hardware FP unintentional it can work, the only place a problem may occur should be the non-secure preempting secure execution case. I think the only thing we are missing now is we did not set FPCCR_S.TS = 1 since we did not realize that user would enable FP in secure world. This would cause the FP register may contain secure information while Non-secure preempting secure execution. Need to go through the settings and double-check. So at least before we finish the estimation I think FPCCR_S.TS should be set to ensure the security. Andrej, have you set this bit while you are using hardware FP? Or just let it go (use default TF-M setting)? Thanks. /Ken From: Soby Mathew <Soby.Mathew(a)arm.com<mailto:Soby.Mathew@arm.com>> Sent: Monday, June 1, 2020 5:25 PM To: Ken Liu <Ken.Liu(a)arm.com<mailto:Ken.Liu@arm.com>>; tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org> Cc: nd <nd(a)arm.com<mailto:nd@arm.com>> Subject: RE: DSP instructions and FPU use Hi, For enabling floating point the ARMv8-M architecture allows the flowing possibilities : * Stacking the basic Floating-point context. * Stacking the basic Floating-point context and the additional Floating-point context. * Activation of Lazy Floating-point state preservation. The easiest way would be to enable FP context stacking for every context switch but it would impact every context switch irrespective of whether FP unit is used in that context or not . I guess this is the approach taken by Andrej ? . The Lazy Floating point state preservation would be better for performance but it would have additional complexity in managing the contexts. Just blue sky thinking here: There could be a middle ground wherein some partitions are allowed to use FP while others are not because they don't really need to. The ones allowed to use FP will need to cater for the additional stack requirement to save FP context. The actual save of the context can be done either on context switch to the partition or lazily. This approach could give the benefit of both performance and memory savings but it requires some analysis and design to be done in TF-M. Best Regards Soby Mathew From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org<mailto:tf-m-bounces@lists.trustedfirmware.org>> On Behalf Of Ken Liu via TF-M Sent: 01 June 2020 09:05 To: tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org> Cc: nd <nd(a)arm.com<mailto:nd@arm.com>> Subject: Re: [TF-M] DSP instructions and FPU use Hi Andrej, You mean the hardware floatpoint can be used in the Secure Partition? That's a good information, can you share us the compiler flags about float-point you are using? Thanks. /Ken From: Andrej Butok <andrey.butok(a)nxp.com<mailto:andrey.butok@nxp.com>> Sent: Monday, June 1, 2020 2:46 PM To: Ken Liu <Ken.Liu(a)arm.com<mailto:Ken.Liu@arm.com>> Cc: tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org> Subject: RE: DSP instructions and FPU use FYI: >> Can you do some experiments on enabling hardware float point and see if it is working In our SDK, the LPC55S HW Float point is enabled for all TFM projects (Kel, GCC/MCUx), and it works. From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org<mailto:tf-m-bounces@lists.trustedfirmware.org>> On Behalf Of Ken Liu via TF-M Sent: Monday, June 1, 2020 8:41 AM To: tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org> Cc: nd <nd(a)arm.com<mailto:nd@arm.com>> Subject: Re: [TF-M] DSP instructions and FPU use Hi Cindy, The reason is we need to estimate the potential security risks after enabling hardware floating-point, so it is set as software FPU as default. Can you do some experiments on enabling hardware float point and see if it is working, and then let's see the patch? That would be helpful for our estimation. During bootup, we cleared the CONTROL.FPCA, and if you access hardware float point in a partition thread should work because it would re-invoke the FPCA bit and make everything work as usual. But as I mentioned, we need to estimate it and give a proper solution and then enable your patch. For DSP, a similar reason is there, we need to take an estimation. But in theory, you can enable the things you have on the hardware, just be caution that the shared resources between S/NS can be the risk (and the resource sharing caused - co-work problem, the context save/load). Thanks. /Ken From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org<mailto:tf-m-bounces@lists.trustedfirmware.org>> On Behalf Of Cindy Chaumont via TF-M Sent: Friday, May 29, 2020 6:39 PM To: tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org> Subject: [TF-M] DSP instructions and FPU use Hello, I am using the GNUARM compiler and LPCXpresso55S69-EVK dev board and I would like to use DSP instructions and FPU (in secure image). About FPU, it seems there is no way to use the hardware floating-point support instead of the software support (see "-msoft-float" flag in CommonConfig.cmake file). Is there a reason for that? Maybe some performance reasons? About DSP, in CompilerGNUARMxy.cmake files, architecture definition is preferred to CPU type and, in my case, "-march=armv8-m.main" flags is chosen (without +dsp option). The solution I found is to only define ARM_CPU_TYPE (and not ARM_CPU_ARCHITECTURE) to use "-mcpu=cortex-m33" flag instead of "-march=armv8-m.main". So I can use DSP instructions. However, I am not sure if this is the best solution. Maybe an option could be added to allow or not the use of DSP instructions? Thank you in advance for the answer, Best regards, Cindy

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TF-M June 2020