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Re: [TF-A] Query SPD/SPMD behavior with EHF

by Achin Gupta

Hi Sandeep, A few comments inline from a SW architecture/FF-A perspective. > On 5 Oct 2020, at 12:28, Sandeep Tripathy via TF-A <tf-a(a)lists.trustedfirmware.org> wrote: > > Hi Olivier, > Appreciate the details. I have a different perception of G0 > interrupts and their relevance to RAS/ critical events. > Comments in line. > Thanks > Sandeep > > On Fri, Oct 2, 2020 at 6:47 PM Olivier Deprez <Olivier.Deprez(a)arm.com> wrote: >> >> Hi Sandeep, >> >> Here are a few more details. >> The reasoning differs when considering pre-Armv8.4 platforms (1) vs Armv8.4 platforms onwards with secure virtualization enabled (2). >> >> Case (1): >> >> EHF framework unifies EL3 exceptions delivered via different vectors and allows them to be handled in a common way. It is also allowing exception delegation handling to lower secure ELs. This framework although primarily used for RAS, is also used for SDEI and platform EL3 interrupts. EL3's role in this case is about trapping and routing the event to appropriate the component (when the interrupt/exception is not handled solely at EL3). >> >> The interoperability between EHF and a Trusted OS is not accurately defined apart from this guidance in EHF documentation: >> "In order for S-EL1 software to handle Non-secure interrupts while having EHF enabled, the dispatcher must adopt a model where Non-secure interrupts are received at EL3, but are then synchronously handled over to S-EL1." >> >> Until then for the specific RAS handling scenario, this was delegated to a StandaloneMM partition running at S-EL0 (through the SPM-MM implementation) and not necessarily delegated to a TOS. > > Reliability is provided by the feature of G0 interrupt that it can not > be masked by lower ELs. Such interrupt being handled at EL3 or being > delegated to other components does not impact the > reliable feature of G0 interrupt. Sure its handling must be offloaded > to other components to keep EL3 firmware light. But If it were just > about handling an interrupt then it could have been entirely handled > in each state without even requiring an EL3 interrupt type. Reliability in RAS is a different concept. RAS error interrupts do not provide reliability. They report unreliable operation. Routing RAS interrupts to EL3 is an implementation choice called Firmware First Handling (FFH). Indeed, the interrupts could be routed to a lower EL which is called Kernel first handling (KFH). For e.g. an implementation could decide to handle corrected errors Kernel first. Uncorrected errors could be routed to a platform controller instead of firmware or be routed to both. There is no single solution. With FFH, the main requirement is that an uncorrected error must be handled even if the Normal world is not in a position to do so. There are non-technical requirements too but lets not go there. So I don’t think there is a requirement that "no lower EL" should be able to mask the interrupt. EL3/S-EL1 and EL3/S-EL2 are at the same privilege level as far as access to the physical address space is concerned. G0 interrupts could be routed to EL3 but they can be disabled by S-EL1 or S-EL2 by programming the GIC distributor. The main point being that software in all privileged exception levels in the Secure world must be trusted to handle RAS errors in the Normal world. Routing G0 interrupts to EL3 is not a silver bullet. When support for FFH was added to TF-A, there was no use case to put software in S-EL1. This EL is owned by TF-A which deploys a simple shim layer. The EHF was developed with this assumption in mind. If your requirement is to put a Trusted OS in S-EL1 and continue doing RAS error handling, then the requirements of the Trusted OS w.r.t the interrupt routing model must be factored in. Hence, the question about what exactly are your requirements. I can understand the desire to reuse EHF but it cannot come at the cost of not meeting the TOS requirements. It needs a SW architecture discussion first. It might be possible to preempt S-EL1 and route RAS errors to EL3 in some cases. A cooperative model (2) between S-EL1 and EL3 (as Olivier described) is what most Trusted OSs implement today. It would be good to understand why that would not work for RAS. > >> >> In order to better help you, we would need more information on the scenario you intend to achieve, and the environment (Arm architecture version and extensions, GIC version). >> Or maybe your question was out of curiosity for the longer term approach (2) as described below? > > As per sbsa level III spec: sbsa non secure watchdog WS1 (reset) must > be targeted at EL3. The patch in review ref: > https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/5495 > And we would want a watchdog interrupt to preempt all execution > context. I would expect the same with any RAS or SDEI critical prio > events. Thanks for pointing this out! SBSA applies to the Server segment. It was reasonable to assume that Secure firmware almost entirely resides in EL3. Hence the guidance. We will look at rewording this in a future release. The intent is that since it is a Non-secure Watchdog, the WS1 signal must not be masked by the Normal world. The BSA applies to all segments. It leaves routing of WS1 implementation defined as long as the Normal world cannot mask it. It could be routed to S-EL1 or S-EL2 if that fulfils the requirement. > Another misc application of our platform is to be able to forcefully > turn off/ halt/ just ping any core at any execution context (S/NS). > These motivated me to leverage EHF. But the idea of dropping EHF in > future designs makes me think now ! > > Our current system is pre Armv8.4. We will stick to case (1). Case > (2) ie SPMD was just my quoricity. However, I felt PSA-FFA may > replace TOS specific SPDs someday. > Making SPMD relevant in this discussion even with pre 8.4 systems. > Because at least the TOS will have to follow one policy. The SPMD is indeed meant to replace TOS specific SPDs. It is meant to cater for the RAS use case as well. From an FF-A perspective, a cooperative approach is simpler. I would like to understand why this would not work for RAS error interrupts as well. Reuse of EHF is an implementation level discussion and I don’t think that is off the table even with (2). > >> >> Case (2): >> >> As a general rule, it is preferred that EL3 reduces its footprint and minimises platform specific handling code. > > Agreed. Applies to case(1) aswell and heavy lifting to be delegated > to lower ELs in either security states. My concern is on 'Taking' the > interrupt handling (mjust)can be delegated. It would certainly be desirable to reuse the EHF. However, it is not possible to delegate the heavy lifting to preempted software in S-EL1 or S-EL2 without significantly increasing their complexity. This is not the current direction of travel of FF-A. > >> EHF framework would most probably not be enabled at all. >> The priority logic provided by the GIC PMR register to mask NS interrupts cannot really work as before because all of trusted EL3/S-EL2 and untrusted S-EL1 SPs can manipulate this register. > > This is a limitation. This can be taken care of by cooperative > software design. ie. S_EL2/S_EL1 will not set PMR out of its range. > And the platform defines what's EL3 priority range. > GIC_LOWEST_EL3_PRI. This falls under the solution space. It would be good to understand what is it you want to run on S-EL1/S-EL2 first. > >> Any secure/non-secure interrupt triggered while running SEL1/SEL0 is trapped first by the S-EL2 firmware (or the so-called SPMC). This translates into SCR_EL3.FIQ/IRQ=0 in the secure world. >> Group1NS interrupts are redirected to SPMD for routing to NWd. >> >> A Group0 interrupt is possibly redirected to a platform driver into an S-EL1 secure partition (e.g. a RAS handling service). >> Hence it does no longer hold true that Group0 interrupts are necessarily qualified as "EL3 interrupts". >> It is still possible to redirect Group0 interrupts from S-EL2 to EL3 and be handled there, but as said, this is a less preferred approach. >> >> Either way when NWd runs (with SCR_EL3.FIQ=1/IRQ=0), a Group1S/Group0 secure interrupt is trapped at EL3 and routed to SPMD then SPMC. >> The SPMC can take the decision to resume the secure partition which registered the corresponding secure INTID. >> >> This design does mean that SDEI interrupt handling would need SPMC and BL31 collaboration and this is something we are working on. > > I understood this scheme. But it means RAS interrupts and other > critical events will always have blackout periods even with proper > software design. RAS interrupts will have blackout periods even if a SMC is handled entirely in EL3. How is routing them to S-EL1 or S-EL2 any different? Afaiu, the RAS architecture spec does not lay down any time limits on by when an error must be reported. All RAS errors are not critical errors. Even critical errors e.g. uncontainable errors report something that has already happened. With unrecoverable errors, ESBs ensure that the problem is contained to a particular EL or Security state. Could you elaborate on what timing requirements you have and why a cooperative model would cause problems? > Whereas with the other routing model scheme the reliability of EHF > handlers can be retained with the constraint of PMR ranges. There may > be something > I am missing. I don’t think “reliability” is an argument here. It is about reusing the EHF in EL3. It is not off the table but we cannot overlook other evolutions in the software and hardware architecture since the EHF was written. Let me know what you think. Cheers, Achin > >> >> Hope this helps. >> >> Regards, >> Olivier. >> >> >> ________________________________________ >> From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> on behalf of Olivier Deprez via TF-A <tf-a(a)lists.trustedfirmware.org> >> Sent: 28 September 2020 14:01 >> To: Sandeep Tripathy; Soby Mathew >> Cc: tf-a(a)lists.trustedfirmware.org; nd >> Subject: Re: [TF-A] Query SPD/SPMD behavior with EHF >> >> Hi Sandeep, >> >> Your question is very valid and we're discussing options internally. >> >> We will come back to you with a consolidated answer shortly. >> >> Regards, >> Olivier. >> >> ________________________________________ >> From: Sandeep Tripathy >> Sent: Monday, September 28, 2020 05:28 >> To: Soby Mathew >> Cc: Dan Handley; tf-a(a)lists.trustedfirmware.org; nd; Olivier Deprez >> Subject: Re: [TF-A] Query SPD/SPMD behavior with EHF >> >> >> Thanks Soby and Dan for confirmation on TSPD. I can see a few more gaps >> in the related area. >> >> "The EL3 interrupts (G0 interrupts) should be able to pre-empt Fast >> SMC i.e. any execution context for that matter ". >> This should apply to all SPDs including SPMD. However I learned from >> @Oliver that SPMD/SPMC design traps FIQs to S_EL2. >> >> In that case a RAS interrupt can be masked by S_EL2 software (eg: >> Hafnium). Probably by design it will be ensured that S_EL2 will never >> mask the physical FIQ ? >> >> S_EL2 FIQ handler will exit to EL3/SPMD by SMC call. And depending on >> the pending interrupt type either it can exit to NWd OR invoke el3 fiq >> vector handler synchronously ? >> >> Are there limitations if we trap fiq to EL3 instead ? >> >> Thanks >> Sandeep >> On Fri, Sep 18, 2020 at 6:26 PM Soby Mathew <Soby.Mathew(a)arm.com> wrote: >>> >>> Hi Sandeep >>> >>>> Except during yielding SMC ‘disable_intr_rm_local(INTR_TYPE_NS, SECUE);’ is in effect. Intention is to avoid NS interrupt preempt secure execution (Fast SMC). >>>> But I think that will also disable G0 interrupt as both NS interrupt and G0 interrupt are on FIQ. >>>> EHF already ensures this by GIC PMR adjustment. So disabling routing model seems unnecessary in this case. >>>> This is my understanding from the code please confirm if this is correct. >>> >>> The EL3 interrupts (G0 interrupts) should be able to pre-empt Fast SMC. Hence the usage of GIC PMR to mask the NS interrupts. As Dan says, the TSP_NS_INTR_ASYNC_PREEMPT predates the EHF design and it seems there is a problem as you describe. >>> >>>> EHF already ensures this by GIC PMR adjustment. So disabling routing model seems unnecessary in this case. >>>> This is my understanding from the code please confirm if this is correct. >>> >>> You are right. Routing model manipulation is not required when EL3 interrupts are present as GIC PMR manipulation should take care of the required behaviour for yielding vs atomic SMC. You also need to ensure it works as expected when EL3 interrupts are not enabled and when EHF is disabled. >>> >>> Best Regards >>> Soby Mathew >>> >>>> -----Original Message----- >>>> From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Sandeep >>>> Tripathy via TF-A >>>> Sent: 17 September 2020 16:53 >>>> To: Dan Handley <Dan.Handley(a)arm.com> >>>> Cc: tf-a(a)lists.trustedfirmware.org >>>> Subject: Re: [TF-A] Query TSPD behavior with EHF >>>> >>>> Hi Dan, >>>> I am not sure if this is mentioned anywhere in any documents but I think >>>> EHF handlers should be able to preempt all execution contexts at lower ELs >>>> and lower ELs should never be able to mask such interrupts. >>>> If the behavioral expectation is set the implementation can be fixed. >>>> >>>> Thanks >>>> Sandeep >>>> >>>> On Thu, Sep 17, 2020 at 7:57 PM Dan Handley via TF-A <tf- >>>> a(a)lists.trustedfirmware.org> wrote: >>>>> >>>>> A correction... >>>>> >>>>>> -----Original Message----- >>>>>> From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Dan >>>>>> Handley via TF-A >>>>>> Sent: 17 September 2020 15:14 >>>>>>>> >>>>>>>> I want to handle something similar in OP-TEED along with EHF >>>>>>>> depending on >>>>>>> what is the expected behavior. >>>>>>>> >>>>>> Hmm, I thought OP-TEED was more like the >>>> TSP_NS_INTR_ASYNC_PREEMPT=0 >>>>>> case, where NS interrupts are routed to S-EL1 while processing a >>>>>> yielding SMC in S- EL1? Perhaps that's a better TSPD config for you to >>>> follow? >>>>>> >>>>> Sorry, if EL3_EXCEPTION_HANDLING=1 then obviously NS interrupts are >>>> routed to EL3 first, but the TSPD re-enables NS interrupts before handing >>>> over to the TSP to handle yielding calls, via a call to >>>> ehf_allow_ns_preemption. >>>>> >>>> >>>> Right, that is the case for yielding SMC handling where both NS interrupts >>>> and EL3/G0 interrupts can preempt the S_EL1/S_EL2 context. >>>> But I would expect the same routing model even for 'Fast SMC' unlike what is >>>> happening in TSPD. >>>> >>>>> Dan. >>>>> >>>>> -- >>>>> TF-A mailing list >>>>> TF-A(a)lists.trustedfirmware.org >>>>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >>>> -- >>>> TF-A mailing list >>>> TF-A(a)lists.trustedfirmware.org >>>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> >> -- >> TF-A mailing list >> TF-A(a)lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a > -- > TF-A mailing list > TF-A(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a

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Re: [TF-A] Nailgun

by Joanna Farley

Hi Varun, The Arm security support pages provides official responses to questions related to security vulnerabilities. [https://developer.arm.com/support/arm-security-updates] Trustedfirmware.org provides Security Centre pages covering the security incident handling and vulnerability disclosure process for hosted projects. [https://developer.trustedfirmware.org/w/collaboration/security_center/] You can find information regarding Nailgun on the following Arm security support FAQ page [https://developer.arm.com/support/arm-security-updates/speculative-processo…]. If you have further questions then please email arm-security(a)arm.com<mailto:arm-security@arm.com> as mentioned in the Arm security support pages. Joanna From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> on behalf of Varun Wadekar via TF-A <tf-a(a)lists.trustedfirmware.org> Reply to: Varun Wadekar <vwadekar(a)nvidia.com> Date: Monday, 28 September 2020 at 21:53 To: "tf-a(a)lists.trustedfirmware.org" <tf-a(a)lists.trustedfirmware.org> Subject: [TF-A] Nailgun Hi, Recently, I learned about Nailgun [1] – leak information by snooping across privilege boundaries with the help of CoreSight. The proof of concept uses Raspberry Pi3 (uses Cortex A-53 CPUs) platform to demonstrate the exploit. Has anyone reviewed this attack and does it affect other Arm v8 CPUs too? Do we have support in TF-A to disable CoreSight to mitigate against such attacks? Are there any other mitigations against this attack? -Varun [1] https://github.com/ningzhenyu/nailgun

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TF-A LTS wiki page

by Varun Wadekar

Hello team, After the recent discussion in the tech forums for the need of a LTS release, I have create a wiki page [1] on tf.org to discuss how we should move forward. The page is expected to be a "live" document and the intention is to allow the community to capture current problems and expectations from the LTS version. Request you to review the page and provide feedback. Thanks, -Varun [1] https://developer.trustedfirmware.org/w/tf_a/lts_proposal/

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Re: [TF-A] BL31 as bootloader

by Alexei Fedorov

Hi Ravi, Have you tried to use RESET_TO_BL31 build option for your platform? Regards. Alexei ________________________________ From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> on behalf of rkohli2000 gmail via TF-A <tf-a(a)lists.trustedfirmware.org> Sent: 07 October 2020 17:01 To: tf-a(a)lists.trustedfirmware.org <tf-a(a)lists.trustedfirmware.org> Subject: [TF-A] BL31 as bootloader Hi, I'm a new user and sorry for some basic TF-A questions. Any guidance is appreciated. I'm am able boot the TF-A bl31.bin image itself on my i.MX8QM MEK platform without using u-boot. I can use the imx-mkimage tool to create a flash or eMMC bootable image (flash.bin). Here, I can specify this container image with both bl31.bin and a separate custom app at a give flash address. This is without any security requirements or dependencies. Can I use the T-FA bl31.bin image to act as a first stage bootloader (without u-boot) and then launch a "custom" bare metal app for Cortex-A53 (for example) on the i.MX8QM at the given (BL33) entry point 0x80020000 address ? Thanks in advance. Ravi -- TF-A mailing list TF-A(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a

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BL31 as bootloader

by rkohli2000 gmail

Hi, I'm a new user and sorry for some basic TF-A questions. Any guidance is appreciated. I'm am able boot the TF-A bl31.bin image itself on my i.MX8QM MEK platform without using u-boot. I can use the imx-mkimage tool to create a flash or eMMC bootable image (flash.bin). Here, I can specify this container image with both bl31.bin and a separate custom app at a give flash address. This is without any security requirements or dependencies. Can I use the T-FA bl31.bin image to act as a first stage bootloader (without u-boot) and then launch a "custom" bare metal app for Cortex-A53 (for example) on the i.MX8QM at the given (BL33) entry point 0x80020000 address ? Thanks in advance. Ravi

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TF-A Tech Forum Agenda @ Thr 8th October 2020 16:00-1700 BST

by Joanna Farley

Hi All, The next TF-A Tech Forum is scheduled for Thu 8th October 2020 16:00 – 17:00 (BST). A reoccurring meeting invite has been sent out to the subscribers of this TF-A mailing list. If you don’t have this please let me know. Agenda: * Measured Boot Support in TF-A * Presented by Alexei Fedorov and Javier Almansa Sobrino * Update on the support for Measured Boot in TF-A along with an overview of test cases for integration with a TPM service * Optional TF-A Mailing List Topic Discussions If TF-A contributors have anything they wish to present at any future TF-A tech forum please contact me to have that scheduled. Previous sessions, both recording and presentation material can be found on the trustedfirmware.org TF-A Technical meeting webpage: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/ A scheduling tracking page is also available to help track sessions suggested and being prepared: https://developer.trustedfirmware.org/w/tf_a/tf-a-tech-forum-scheduling/ Final decisions on what will be presented will be shared a few days before the next meeting and shared on the TF-A mailing list. Thanks Joanna

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TF-A image construction

by rkohli2000 gmail

Hi, Sorry for the wide distribution and if this isn't the appropriate board. I'm interested in TF-A image construction for the i.MX8QM SoC platform and basic image construction instructions. I'd like to understand how to deploy a user application for the Cortex-A53 core and flash image construction. For example, how to deploy BL31.bin and launch a user app for the platform and what does the following TF-A console log imply for user apps: INFO: Entry point address = 0x80020000 INFO: SPSR = 0x3c9 Any intro info is appreciated. Thanks again. Regards Ravi

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Re: [TF-A] Query SPD/SPMD behavior with EHF

by Olivier Deprez

Hi Sandeep, Here are a few more details. The reasoning differs when considering pre-Armv8.4 platforms (1) vs Armv8.4 platforms onwards with secure virtualization enabled (2). Case (1): EHF framework unifies EL3 exceptions delivered via different vectors and allows them to be handled in a common way. It is also allowing exception delegation handling to lower secure ELs. This framework although primarily used for RAS, is also used for SDEI and platform EL3 interrupts. EL3's role in this case is about trapping and routing the event to appropriate the component (when the interrupt/exception is not handled solely at EL3). The interoperability between EHF and a Trusted OS is not accurately defined apart from this guidance in EHF documentation: "In order for S-EL1 software to handle Non-secure interrupts while having EHF enabled, the dispatcher must adopt a model where Non-secure interrupts are received at EL3, but are then synchronously handled over to S-EL1." Until then for the specific RAS handling scenario, this was delegated to a StandaloneMM partition running at S-EL0 (through the SPM-MM implementation) and not necessarily delegated to a TOS. In order to better help you, we would need more information on the scenario you intend to achieve, and the environment (Arm architecture version and extensions, GIC version). Or maybe your question was out of curiosity for the longer term approach (2) as described below? Case (2): As a general rule, it is preferred that EL3 reduces its footprint and minimises platform specific handling code. EHF framework would most probably not be enabled at all. The priority logic provided by the GIC PMR register to mask NS interrupts cannot really work as before because all of trusted EL3/S-EL2 and untrusted S-EL1 SPs can manipulate this register. Any secure/non-secure interrupt triggered while running SEL1/SEL0 is trapped first by the S-EL2 firmware (or the so-called SPMC). This translates into SCR_EL3.FIQ/IRQ=0 in the secure world. Group1NS interrupts are redirected to SPMD for routing to NWd. A Group0 interrupt is possibly redirected to a platform driver into an S-EL1 secure partition (e.g. a RAS handling service). Hence it does no longer hold true that Group0 interrupts are necessarily qualified as "EL3 interrupts". It is still possible to redirect Group0 interrupts from S-EL2 to EL3 and be handled there, but as said, this is a less preferred approach. Either way when NWd runs (with SCR_EL3.FIQ=1/IRQ=0), a Group1S/Group0 secure interrupt is trapped at EL3 and routed to SPMD then SPMC. The SPMC can take the decision to resume the secure partition which registered the corresponding secure INTID. This design does mean that SDEI interrupt handling would need SPMC and BL31 collaboration and this is something we are working on. Hope this helps. Regards, Olivier. ________________________________________ From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> on behalf of Olivier Deprez via TF-A <tf-a(a)lists.trustedfirmware.org> Sent: 28 September 2020 14:01 To: Sandeep Tripathy; Soby Mathew Cc: tf-a(a)lists.trustedfirmware.org; nd Subject: Re: [TF-A] Query SPD/SPMD behavior with EHF Hi Sandeep, Your question is very valid and we're discussing options internally. We will come back to you with a consolidated answer shortly. Regards, Olivier. ________________________________________ From: Sandeep Tripathy Sent: Monday, September 28, 2020 05:28 To: Soby Mathew Cc: Dan Handley; tf-a(a)lists.trustedfirmware.org; nd; Olivier Deprez Subject: Re: [TF-A] Query SPD/SPMD behavior with EHF Thanks Soby and Dan for confirmation on TSPD. I can see a few more gaps in the related area. "The EL3 interrupts (G0 interrupts) should be able to pre-empt Fast SMC i.e. any execution context for that matter ". This should apply to all SPDs including SPMD. However I learned from @Oliver that SPMD/SPMC design traps FIQs to S_EL2. In that case a RAS interrupt can be masked by S_EL2 software (eg: Hafnium). Probably by design it will be ensured that S_EL2 will never mask the physical FIQ ? S_EL2 FIQ handler will exit to EL3/SPMD by SMC call. And depending on the pending interrupt type either it can exit to NWd OR invoke el3 fiq vector handler synchronously ? Are there limitations if we trap fiq to EL3 instead ? Thanks Sandeep On Fri, Sep 18, 2020 at 6:26 PM Soby Mathew <Soby.Mathew(a)arm.com> wrote: > > Hi Sandeep > > > Except during yielding SMC ‘disable_intr_rm_local(INTR_TYPE_NS, SECUE);’ is in effect. Intention is to avoid NS interrupt preempt secure execution (Fast SMC). > > But I think that will also disable G0 interrupt as both NS interrupt and G0 interrupt are on FIQ. > > EHF already ensures this by GIC PMR adjustment. So disabling routing model seems unnecessary in this case. > > This is my understanding from the code please confirm if this is correct. > > The EL3 interrupts (G0 interrupts) should be able to pre-empt Fast SMC. Hence the usage of GIC PMR to mask the NS interrupts. As Dan says, the TSP_NS_INTR_ASYNC_PREEMPT predates the EHF design and it seems there is a problem as you describe. > > > EHF already ensures this by GIC PMR adjustment. So disabling routing model seems unnecessary in this case. > > This is my understanding from the code please confirm if this is correct. > > You are right. Routing model manipulation is not required when EL3 interrupts are present as GIC PMR manipulation should take care of the required behaviour for yielding vs atomic SMC. You also need to ensure it works as expected when EL3 interrupts are not enabled and when EHF is disabled. > > Best Regards > Soby Mathew > > > -----Original Message----- > > From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Sandeep > > Tripathy via TF-A > > Sent: 17 September 2020 16:53 > > To: Dan Handley <Dan.Handley(a)arm.com> > > Cc: tf-a(a)lists.trustedfirmware.org > > Subject: Re: [TF-A] Query TSPD behavior with EHF > > > > Hi Dan, > > I am not sure if this is mentioned anywhere in any documents but I think > > EHF handlers should be able to preempt all execution contexts at lower ELs > > and lower ELs should never be able to mask such interrupts. > > If the behavioral expectation is set the implementation can be fixed. > > > > Thanks > > Sandeep > > > > On Thu, Sep 17, 2020 at 7:57 PM Dan Handley via TF-A <tf- > > a(a)lists.trustedfirmware.org> wrote: > > > > > > A correction... > > > > > > > -----Original Message----- > > > > From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Dan > > > > Handley via TF-A > > > > Sent: 17 September 2020 15:14 > > > > > > > > > > > > I want to handle something similar in OP-TEED along with EHF > > > > > > depending on > > > > > what is the expected behavior. > > > > > > > > > > Hmm, I thought OP-TEED was more like the > > TSP_NS_INTR_ASYNC_PREEMPT=0 > > > > case, where NS interrupts are routed to S-EL1 while processing a > > > > yielding SMC in S- EL1? Perhaps that's a better TSPD config for you to > > follow? > > > > > > > Sorry, if EL3_EXCEPTION_HANDLING=1 then obviously NS interrupts are > > routed to EL3 first, but the TSPD re-enables NS interrupts before handing > > over to the TSP to handle yielding calls, via a call to > > ehf_allow_ns_preemption. > > > > > > > Right, that is the case for yielding SMC handling where both NS interrupts > > and EL3/G0 interrupts can preempt the S_EL1/S_EL2 context. > > But I would expect the same routing model even for 'Fast SMC' unlike what is > > happening in TSPD. > > > > > Dan. > > > > > > -- > > > TF-A mailing list > > > TF-A(a)lists.trustedfirmware.org > > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a > > -- > > TF-A mailing list > > TF-A(a)lists.trustedfirmware.org > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a

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New Defects reported by Coverity Scan for ARM-software/arm-trusted-firmware

by scan-admin＠coverity.com

Hi, Please find the latest report on new defect(s) introduced to ARM-software/arm-trusted-firmware found with Coverity Scan. 3 new defect(s) introduced to ARM-software/arm-trusted-firmware found with Coverity Scan. 1 defect(s), reported by Coverity Scan earlier, were marked fixed in the recent build analyzed by Coverity Scan. New defect(s) Reported-by: Coverity Scan Showing 3 of 3 defect(s) ** CID 362943: Insecure data handling (TAINTED_SCALAR) ________________________________________________________________________________________________________ *** CID 362943: Insecure data handling (TAINTED_SCALAR) /common/fdt_fixup.c: 437 in fdt_adjust_gic_redist() 431 432 /* 433 * The redistributor is described in the second "reg" entry. 434 * So we have to skip one address and one size cell, then another 435 * address cell to get to the second size cell. 436 */ >>> CID 362943: Insecure data handling (TAINTED_SCALAR) >>> Passing tainted variable "sc * 4" to a tainted sink. 437 return fdt_setprop_inplace_namelen_partial(dtb, offset, "reg", 3, 438 (ac + sc + ac) * 4, 439 val, sc * 4); ** CID 362942: Integer handling issues (OVERFLOW_BEFORE_WIDEN) /common/fdt_fixup.c: 428 in fdt_adjust_gic_redist() ________________________________________________________________________________________________________ *** CID 362942: Integer handling issues (OVERFLOW_BEFORE_WIDEN) /common/fdt_fixup.c: 428 in fdt_adjust_gic_redist() 422 } 423 424 if (sc == 1) { 425 redist_size_32 = cpu_to_fdt32(nr_cores * gicr_frame_size); 426 val = &redist_size_32; 427 } else { >>> CID 362942: Integer handling issues (OVERFLOW_BEFORE_WIDEN) >>> Potentially overflowing expression "nr_cores * gicr_frame_size" with type "unsigned int" (32 bits, unsigned) is evaluated using 32-bit arithmetic, and then used in a context that expects an expression of type "uint64_t" (64 bits, unsigned). 428 redist_size_64 = cpu_to_fdt64(nr_cores * gicr_frame_size); 429 val = &redist_size_64; 430 } 431 432 /* 433 * The redistributor is described in the second "reg" entry. ** CID 362941: Integer handling issues (BAD_SHIFT) /mbedtls/library/bignum.c: 1713 in mbedtls_int_div_int() ________________________________________________________________________________________________________ *** CID 362941: Integer handling issues (BAD_SHIFT) /mbedtls/library/bignum.c: 1713 in mbedtls_int_div_int() 1707 * Normalize the divisor, d, and dividend, u0, u1 1708 */ 1709 s = mbedtls_clz( d ); 1710 d = d << s; 1711 1712 u1 = u1 << s; >>> CID 362941: Integer handling issues (BAD_SHIFT) >>> In expression "u0 >> 64UL - s", right shifting by more than 63 bits has undefined behavior. The shift amount, "64UL - s", is 64. 1713 u1 |= ( u0 >> ( biL - s ) ) & ( -(mbedtls_mpi_sint)s >> ( biL - 1 ) ); 1714 u0 = u0 << s; 1715 1716 d1 = d >> biH; 1717 d0 = d & uint_halfword_mask; 1718 ________________________________________________________________________________________________________ To view the defects in Coverity Scan visit, https://u15810271.ct.sendgrid.net/ls/click?upn=HRESupC-2F2Czv4BOaCWWCy7my0P…

5 years, 1 month

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STM32MP1: Adding TF-A causes kernel errors

by Jan Kiszka

Hi Yann, not sure if TF-A is the one to blame, but it's the variable that triggers the following on the STM32MP15x eval board for me. I think I'm following tfa/docs/plat/stm32mp1.rst and u-boot/doc/board/st/stm32mp1.rst correctly. Working: - U-Boot 2020.07, stm32mp15_basic_defconfig - Linux 5.9-rc7 (or 5.4.x), defconfig [ 0.000000] Memory: 815540K/917500K available (13312K kernel code, 1800K rwdata, 5452K rodata, 2048K init, 407K bss, 36424K reserved, 65536K cma-reserved, 196604K highmem) Failing: - TF-A 2.3, PLAT=stm32mp1 ARCH=aarch32 ARM_ARCH_MAJOR=7 \ AARCH32_SP=sp_min STM32MP_SDMMC=1 STM32MP_EMMC=1 STM32MP_RAW_NAND=1 \ STM32MP_SPI_NAND=1 STM32MP_SPI_NOR=1 DTB_FILE_NAME=stm32mp157c-ev1.dtb - U-Boot 2020.07, stm32mp15_trusted_defconfig - Linux as above [ 0.000000] Memory: 881076K/917500K available (13312K kernel code, 1800K rwdata, 5452K rodata, 2048K init, 407K bss, 4294938184K reserved, 65536K cma-reserved, 262140K highmem) which causes issues like [ 0.047215] BUG: Bad page state in process swapper/0 pfn:fa000 [ 0.047236] page:(ptrval) refcount:0 mapcount:-128 mapping:00000000 index:0x1 pfn:0xfa000 [ 0.047249] flags: 0x80000000() CMA [ 0.047273] raw: 80000000 e7f29004 e7f49004 00000000 00000001 0000000b ffffff7f 00000000 [ 0.047281] page dumped because: nonzero mapcount [ 0.047287] Modules linked in: [ 0.047305] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc7 #1 [ 0.047314] Hardware name: STM32 (Device Tree Support) [ 0.047358] [<c0311708>] (unwind_backtrace) from [<c030b88c>] (show_stack+0x10/0x14) [ 0.047384] [<c030b88c>] (show_stack) from [<c0718a40>] (dump_stack+0xc8/0xdc) [ 0.047408] [<c0718a40>] (dump_stack) from [<c047b3c8>] (bad_page+0xdc/0x10c) [ 0.047426] [<c047b3c8>] (bad_page) from [<c047c060>] (__free_pages_ok+0x2e8/0x36c) [ 0.047447] [<c047c060>] (__free_pages_ok) from [<c1623a80>] (init_cma_reserved_pageblock+0x58/0x68) [ 0.047469] [<c1623a80>] (init_cma_reserved_pageblock) from [<c16266c8>] (cma_init_reserved_areas+0x170/0x1c8) [ 0.047491] [<c16266c8>] (cma_init_reserved_areas) from [<c0301ef8>] (do_one_initcall+0x54/0x22c) [ 0.047513] [<c0301ef8>] (do_one_initcall) from [<c160102c>] (kernel_init_freeable+0x188/0x1ec) [ 0.047537] [<c160102c>] (kernel_init_freeable) from [<c0f4a340>] (kernel_init+0x8/0x118) [ 0.047559] [<c0f4a340>] (kernel_init) from [<c03001a8>] (ret_from_fork+0x14/0x2c) [ 0.047570] Exception stack(0xe68b7fb0 to 0xe68b7ff8) [ 0.047584] 7fa0: 00000000 00000000 00000000 00000000 [ 0.047600] 7fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 [ 0.047614] 7fe0: 00000000 00000000 00000000 00000000 00000013 00000000 [ 0.047624] Disabling lock debugging due to kernel taint Still, the system boots, and I can login. That reserved value the kernel finds is obviously off. Does it come from TF-A, is U-Boot causing this in the presence of TF-A, or is the kernel itself getting it wrong? Or am I missing some switch that is not in the kernel defconfig? Thanks, Jan

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TF-A