On 10/01/2020 09:05, shaolin.xie via TF-A wrote:
> Hey all:
>
> We are trying to port ARM Trust-Firmware-A to our design, however, we are facing serious SRAM size problem.
>
> Our target SRAM is 64KB, but the compiled BL2 already taken 60K:
>
> After some evaluation, we found that the MMU table take most of the space. Our questions are:
Hi Shaolin,
There are some options to reduce the memory used for page-tables like
using non-identity virtual to physical mappings. But given your SRAM
size, I suspect you may not save enough to fit BL31.
>
> 1. Can we disable the MMU so we can fit the BL2 into 64KB space?
> (However, in ARM's porting guide, enable MMU and icache/dcache is mandatory. Refer to chapter 7.3 in https://trustedfirmware-a.readthedocs.io/en/latest/getting_started/porting-… <https://trustedfirmware-a.readthedocs.io/en/latest/getting_started/porting-…>.)
This is a possibility although not recommended for performance reasons
and you lose the protection of MMU during BL2 execution. This is not a
configuration we support an I suspect some changes to BL2 code may be
required for this.
>
> 2. In current design, BL31 is run in SRAM. If we enable DDR in BL2 and load BL31 image to DDR, is there any potential issue?
>
> Thanks in advances,
>
>
It is possible to create a secure carve-out in DDR and execute BL31 from
there. It is less `secure` than running from SRAM but it is acceptable
for some market segments depending on the threat model.
You target SRAM of 64 KB is on the lower side and fitting both BL2 and
BL31 in that space could be a challenge.
Could you let us know your BL2 and BL31 size and could you break down
the size in terms of PROGBITS and NOPROG BITS? The BL31 NOPROG BITS are
usually overlayed on top of BL2 memory and this will let us know whether
fitting both in SRAM is even possible. If both cannot fit together in
SRAM, there are other options you can explore like loading BL31 directly
from BootROM or using BL2 as an XIP BootROM image.
Best Regards
Soby Mathew
Another option to BL31 in system memory (DDR) is, which we are exploring,
is loading an image (in our case BL33/Uboot) to system caches (inner L1/L2
& outer LLC/L3 which ever) and initialize the DDR from within it. This is
not trivial though but working successfully with us for Cortex-A15, A53 and
A57 with CCN (Cache Coherent Network 504 and 512) featuring the Last Level
Cache on three of our SoCs.
Marek
On Fri, 10 Jan 2020 at 11:12, Soby Mathew via TF-A <
tf-a(a)lists.trustedfirmware.org> wrote:
> On 10/01/2020 09:05, shaolin.xie via TF-A wrote:
> > Hey all:
> >
> > We are trying to port ARM Trust-Firmware-A to our design, however, we
> are facing serious SRAM size problem.
> >
> > Our target SRAM is 64KB, but the compiled BL2 already taken 60K:
> >
> > After some evaluation, we found that the MMU table take most of the
> space. Our questions are:
> Hi Shaolin,
> There are some options to reduce the memory used for page-tables like
> using non-identity virtual to physical mappings. But given your SRAM
> size, I suspect you may not save enough to fit BL31.
>
> >
> > 1. Can we disable the MMU so we can fit the BL2 into 64KB space?
> > (However, in ARM's porting guide, enable MMU and icache/dcache is
> mandatory. Refer to chapter 7.3 in
> https://trustedfirmware-a.readthedocs.io/en/latest/getting_started/porting-…
> <
> https://trustedfirmware-a.readthedocs.io/en/latest/getting_started/porting-…
> >.)
>
> This is a possibility although not recommended for performance reasons
> and you lose the protection of MMU during BL2 execution. This is not a
> configuration we support an I suspect some changes to BL2 code may be
> required for this.
>
> >
> > 2. In current design, BL31 is run in SRAM. If we enable DDR in BL2 and
> load BL31 image to DDR, is there any potential issue?
> >
> > Thanks in advances,
> >
> >
>
> It is possible to create a secure carve-out in DDR and execute BL31 from
> there. It is less `secure` than running from SRAM but it is acceptable
> for some market segments depending on the threat model.
>
> You target SRAM of 64 KB is on the lower side and fitting both BL2 and
> BL31 in that space could be a challenge.
>
> Could you let us know your BL2 and BL31 size and could you break down
> the size in terms of PROGBITS and NOPROG BITS? The BL31 NOPROG BITS are
> usually overlayed on top of BL2 memory and this will let us know whether
> fitting both in SRAM is even possible. If both cannot fit together in
> SRAM, there are other options you can explore like loading BL31 directly
> from BootROM or using BL2 as an XIP BootROM image.
>
> Best Regards
> Soby Mathew
>
>
>
> --
> TF-A mailing list
> TF-A(a)lists.trustedfirmware.org
> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>
--
Slán,
Marek
Hey all:
We are trying to port ARM Trust-Firmware-A to our design, however, we are facing serious SRAM size problem.
Our target SRAM is 64KB, but the compiled BL2 already taken 60K:
After some evaluation, we found that the MMU table take most of the space. Our questions are:
1. Can we disable the MMU so we can fit the BL2 into 64KB space?
(However, in ARM's porting guide, enable MMU and icache/dcache is mandatory. Refer to chapter 7.3 in https://trustedfirmware-a.readthedocs.io/en/latest/getting_started/porting-… <https://trustedfirmware-a.readthedocs.io/en/latest/getting_started/porting-…>.)
2. In current design, BL31 is run in SRAM. If we enable DDR in BL2 and load BL31 image to DDR, is there any potential issue?
Thanks in advances,
Back on-list.
> One more question, the operation of TrustZone is the same in the armv7-A and Armv8-A architectures, right?
Not exactly…for a description about TZ differences between the Armv7-A and Armv8-A architecture please have a look at this presentation:
https://www.youtube.com/watch?v=q32BEMMxmfwhttps://www.slideshare.net/linaroorg/arm-trusted-firmareforarmv8alcu13
As a reference, all public talks and presentations on TF-A over the years are listed here:
https://developer.trustedfirmware.org/w/tf_a/
Thanks
Matteo
> From: Iñigo Vicente Waliño <inigovicentewalino(a)gmail.com>
> Sent: 09 January 2020 11:21
> To: Matteo Carlini <Matteo.Carlini(a)arm.com>
> Subject: Re: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
> One more question, the operation of TrustZone is the same in the armv7-A and Armv8-A architectures, right?
> Thanks for your answers,
> Iñigo.
Another option is to look at the 96boards platforms:
https://www.96boards.org/product/developerbox/ (that's supported upstream by TF-A https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/tree/plat/socio… )
and the Secure96 mezzanine board
https://www.96boards.org/product/secure96/https://www.96boards.org/blog/getting-started-with-the-secure96-tpm/
but the boot flow with TF-A and this mezzanine board hasn't been officially proved.
Ard and Stuart (cc-ed) have done some investigations and experiment in this direction and might add something.
Thanks
Matteo
> -----Original Message-----
> From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Dan
> Handley via TF-A
> Sent: 09 January 2020 09:56
> To: tf-a(a)lists.trustedfirmware.org
> Subject: Re: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
>
> (Back on the list)
>
> Sorry Iñigo, I don't know enough about the hw capabilities of Raspberry Pi
> and its boot flow to be able to help you further. Olivier gave some more
> pointers.
>
> Dan.
>
>
> From: Iñigo Vicente Waliño <inigovicentewalino(a)gmail.com>
> Sent: 09 January 2020 07:42
> To: Dan Handley <Dan.Handley(a)arm.com>
> Subject: Re: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
>
> Yes, thank you very much.
>
> Then, what I'm trying to say is that if I want a secure boot, I need a trust root.
> If Raspberry Pi cannot provide that trusted root, can I use a TPM?
>
> Iñigo
>
> El mié., 8 ene. 2020 a las 16:32, Dan Handley via TF-A (<tf-
> a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org>>)
> escribió:
> (Back on the list)
>
> By rpi I guess you mean Raspberry Pi?
>
> > How do we ensure that the ROM is safe?
> I'm not sure what you mean by "safe". By definition the ROM is non-
> modifiable but maybe you also want it to be non-readable by normal world
> software?
>
> Although Raspberry Pi contains CPUs that implement TrustZone, I believe
> there is no TrustZone Controller IP policing access to memory so there is
> nothing preventing normal world software from accessing memory that is
> mapped in as secure. Perhaps that is what you mean by "rpi does not provide
> security"? I also don't know what you mean by "a TPM does not work".
>
> Dan.
>
> From: Iñigo Vicente Waliño
> <inigovicentewalino(a)gmail.com<mailto:inigovicentewalino@gmail.com>>
> Sent: 08 January 2020 14:54
> To: Dan Handley <Dan.Handley(a)arm.com<mailto:Dan.Handley@arm.com>>
> Subject: Re: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
>
> Assuming that BL1 is used and implemented in ROM, for example, with an rpi.
> How do we ensure that the ROM is safe? He sought that rpi does not provide
> security and that a TPM does not work. Why?
>
> Thanks.
>
> El mié., 8 ene. 2020 a las 13:21, Dan Handley via TF-A (<tf-
> a(a)lists.trustedfirmware.org<mailto:tf-
> a(a)lists.trustedfirmware.org><mailto:tf-
> a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org>>>)
> escribió:
> Hi Inigo
>
> TrustZone is a trademark referring to the security extensions of the Arm
> architecture. That is separate to BL1, which is the first boot stage of Trusted
> Firmware-A (or some other equivalent boot firmware). The expectation is
> that BL1, if used, is implemented in ROM to provide the Root of Trust for the
> Application Processor (AP).
>
> An alternative flow is for a separate "security processor" to authenticate the
> AP firmware before the AP is released from reset. In such a flow, there is no
> need for BL1 and BL2 since that functionality is provided by the security
> processor. In such a flow, the TF-A RESET_TO_BL31 config can be used (see
> in-source documentation).
>
> A TPM can provide additional security by storing secrets not even visible to
> TrustZone software (e.g. root keys or boot measurements). However, TPMs
> typically don't do firmware authentication on their own; some other
> software will need to use the secrets it stores, e.g. boot firmware may ask
> the TPM verify a signature corresponding to the next boot stage.
>
> > If the TPM is changed to another, is the boot performed?
> That depends on your system design.
>
> Dan.
>
> > -----Original Message-----
> > From: TF-A
> > <tf-a-bounces(a)lists.trustedfirmware.org<mailto:tf-a-bounces@lists.trus
> > tedfirmware.org><mailto:tf-a-bounces@lists.trustedfirmware.org<mailto:
> > tf-a-bounces(a)lists.trustedfirmware.org>>> On Behalf Of Iñigo Vicente
> > Waliño via TF-A
> > Sent: 08 January 2020 10:33
> > To:
> > tf-a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org><
> > mailto:tf-a@lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmwar
> > e.org>>
> > Subject: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
> >
> > Hi,
> >
> > Does ARMv8 TrustZone provide BL1 in a secure ROM? Can a TPM be used
> as
> > a trusted root or is it useless?
> > If the TPM is changed to another, is the boot performed?
> >
> > Thanks,
> > Inigo.
> > --
> > TF-A mailing list
> > TF-A(a)lists.trustedfirmware.org<mailto:TF-A@lists.trustedfirmware.org><
> > mailto:TF-A@lists.trustedfirmware.org<mailto:TF-A@lists.trustedfirmwar
> > e.org>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
> IMPORTANT NOTICE: The contents of this email and any attachments are
> confidential and may also be privileged. If you are not the intended recipient,
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> intended recipient, please notify the sender immediately and do not disclose
> the contents to any other person, use it for any purpose, or store or copy the
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> confidential and may also be privileged. If you are not the intended recipient,
> please notify the sender immediately and do not disclose the contents to any
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> intended recipient, please notify the sender immediately and do not disclose
> the contents to any other person, use it for any purpose, or store or copy the
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(Back on the list)
Sorry Iñigo, I don't know enough about the hw capabilities of Raspberry Pi and its boot flow to be able to help you further. Olivier gave some more pointers.
Dan.
From: Iñigo Vicente Waliño <inigovicentewalino(a)gmail.com>
Sent: 09 January 2020 07:42
To: Dan Handley <Dan.Handley(a)arm.com>
Subject: Re: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
Yes, thank you very much.
Then, what I'm trying to say is that if I want a secure boot, I need a trust root. If Raspberry Pi cannot provide that trusted root, can I use a TPM?
Iñigo
El mié., 8 ene. 2020 a las 16:32, Dan Handley via TF-A (<tf-a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org>>) escribió:
(Back on the list)
By rpi I guess you mean Raspberry Pi?
> How do we ensure that the ROM is safe?
I'm not sure what you mean by "safe". By definition the ROM is non-modifiable but maybe you also want it to be non-readable by normal world software?
Although Raspberry Pi contains CPUs that implement TrustZone, I believe there is no TrustZone Controller IP policing access to memory so there is nothing preventing normal world software from accessing memory that is mapped in as secure. Perhaps that is what you mean by "rpi does not provide security"? I also don't know what you mean by "a TPM does not work".
Dan.
From: Iñigo Vicente Waliño <inigovicentewalino(a)gmail.com<mailto:inigovicentewalino@gmail.com>>
Sent: 08 January 2020 14:54
To: Dan Handley <Dan.Handley(a)arm.com<mailto:Dan.Handley@arm.com>>
Subject: Re: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
Assuming that BL1 is used and implemented in ROM, for example, with an rpi.
How do we ensure that the ROM is safe? He sought that rpi does not provide security and that a TPM does not work. Why?
Thanks.
El mié., 8 ene. 2020 a las 13:21, Dan Handley via TF-A (<tf-a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org><mailto:tf-a@lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org>>>) escribió:
Hi Inigo
TrustZone is a trademark referring to the security extensions of the Arm architecture. That is separate to BL1, which is the first boot stage of Trusted Firmware-A (or some other equivalent boot firmware). The expectation is that BL1, if used, is implemented in ROM to provide the Root of Trust for the Application Processor (AP).
An alternative flow is for a separate "security processor" to authenticate the AP firmware before the AP is released from reset. In such a flow, there is no need for BL1 and BL2 since that functionality is provided by the security processor. In such a flow, the TF-A RESET_TO_BL31 config can be used (see in-source documentation).
A TPM can provide additional security by storing secrets not even visible to TrustZone software (e.g. root keys or boot measurements). However, TPMs typically don't do firmware authentication on their own; some other software will need to use the secrets it stores, e.g. boot firmware may ask the TPM verify a signature corresponding to the next boot stage.
> If the TPM is changed to another, is the boot performed?
That depends on your system design.
Dan.
> -----Original Message-----
> From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org<mailto:tf-a-bounces@lists.trustedfirmware.org><mailto:tf-a-bounces@lists.trustedfirmware.org<mailto:tf-a-bounces@lists.trustedfirmware.org>>> On Behalf Of Iñigo
> Vicente Waliño via TF-A
> Sent: 08 January 2020 10:33
> To: tf-a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org><mailto:tf-a@lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org>>
> Subject: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
>
> Hi,
>
> Does ARMv8 TrustZone provide BL1 in a secure ROM? Can a TPM be used as a
> trusted root or is it useless?
> If the TPM is changed to another, is the boot performed?
>
> Thanks,
> Inigo.
> --
> TF-A mailing list
> TF-A(a)lists.trustedfirmware.org<mailto:TF-A@lists.trustedfirmware.org><mailto:TF-A@lists.trustedfirmware.org<mailto:TF-A@lists.trustedfirmware.org>>
> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
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Hi,
To add to Dan's observation about rpi lacking TZ memory controller:
Notice the first subsystem to boot on BCM SoC is the VideoCore (which itself releases ARM cores resets). Thus, there are early boot stages running even before TF-A gets handed over. So it needs trusting the VC ROM and VC bootloader (residing on SD card, or EEPROM from rpi4). As to whether those early components get verified by the BCM chip, this is not documented publicly AFAIK.
I extrapolate "TPM does not work" means the "public rpi" is good for prototyping TZ and/or a TPM solution. Although it is eventually not directly usable as a production platform for such use cases.
Regards,
Olivier.
________________________________________
From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> on behalf of Dan Handley via TF-A <tf-a(a)lists.trustedfirmware.org>
Sent: 08 January 2020 16:32
To: tf-a(a)lists.trustedfirmware.org
Subject: Re: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
(Back on the list)
By rpi I guess you mean Raspberry Pi?
> How do we ensure that the ROM is safe?
I'm not sure what you mean by "safe". By definition the ROM is non-modifiable but maybe you also want it to be non-readable by normal world software?
Although Raspberry Pi contains CPUs that implement TrustZone, I believe there is no TrustZone Controller IP policing access to memory so there is nothing preventing normal world software from accessing memory that is mapped in as secure. Perhaps that is what you mean by "rpi does not provide security"? I also don't know what you mean by "a TPM does not work".
Dan.
From: Iñigo Vicente Waliño <inigovicentewalino(a)gmail.com>
Sent: 08 January 2020 14:54
To: Dan Handley <Dan.Handley(a)arm.com>
Subject: Re: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
Assuming that BL1 is used and implemented in ROM, for example, with an rpi.
How do we ensure that the ROM is safe? He sought that rpi does not provide security and that a TPM does not work. Why?
Thanks.
El mié., 8 ene. 2020 a las 13:21, Dan Handley via TF-A (<tf-a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org>>) escribió:
Hi Inigo
TrustZone is a trademark referring to the security extensions of the Arm architecture. That is separate to BL1, which is the first boot stage of Trusted Firmware-A (or some other equivalent boot firmware). The expectation is that BL1, if used, is implemented in ROM to provide the Root of Trust for the Application Processor (AP).
An alternative flow is for a separate "security processor" to authenticate the AP firmware before the AP is released from reset. In such a flow, there is no need for BL1 and BL2 since that functionality is provided by the security processor. In such a flow, the TF-A RESET_TO_BL31 config can be used (see in-source documentation).
A TPM can provide additional security by storing secrets not even visible to TrustZone software (e.g. root keys or boot measurements). However, TPMs typically don't do firmware authentication on their own; some other software will need to use the secrets it stores, e.g. boot firmware may ask the TPM verify a signature corresponding to the next boot stage.
> If the TPM is changed to another, is the boot performed?
That depends on your system design.
Dan.
> -----Original Message-----
> From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org<mailto:tf-a-bounces@lists.trustedfirmware.org>> On Behalf Of Iñigo
> Vicente Waliño via TF-A
> Sent: 08 January 2020 10:33
> To: tf-a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org>
> Subject: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
>
> Hi,
>
> Does ARMv8 TrustZone provide BL1 in a secure ROM? Can a TPM be used as a
> trusted root or is it useless?
> If the TPM is changed to another, is the boot performed?
>
> Thanks,
> Inigo.
> --
> TF-A mailing list
> TF-A(a)lists.trustedfirmware.org<mailto:TF-A@lists.trustedfirmware.org>
> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.
IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.
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Hi,
We are intending to move the updates to the change log from completely release based to more rolling updates. I have created a new change log file in the docs directory (change-log-upcoming.rst) for changes that need to be included for the upcoming release: https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/3081. The intention is for individual developers to update the document with the relevant patch as the code change is being made. The usual change log document (docs/change-log.rst) will be updated at release time to include all changes for each release.
Thanks,
Lauren
(Back on the list)
By rpi I guess you mean Raspberry Pi?
> How do we ensure that the ROM is safe?
I'm not sure what you mean by "safe". By definition the ROM is non-modifiable but maybe you also want it to be non-readable by normal world software?
Although Raspberry Pi contains CPUs that implement TrustZone, I believe there is no TrustZone Controller IP policing access to memory so there is nothing preventing normal world software from accessing memory that is mapped in as secure. Perhaps that is what you mean by "rpi does not provide security"? I also don't know what you mean by "a TPM does not work".
Dan.
From: Iñigo Vicente Waliño <inigovicentewalino(a)gmail.com>
Sent: 08 January 2020 14:54
To: Dan Handley <Dan.Handley(a)arm.com>
Subject: Re: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
Assuming that BL1 is used and implemented in ROM, for example, with an rpi.
How do we ensure that the ROM is safe? He sought that rpi does not provide security and that a TPM does not work. Why?
Thanks.
El mié., 8 ene. 2020 a las 13:21, Dan Handley via TF-A (<tf-a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org>>) escribió:
Hi Inigo
TrustZone is a trademark referring to the security extensions of the Arm architecture. That is separate to BL1, which is the first boot stage of Trusted Firmware-A (or some other equivalent boot firmware). The expectation is that BL1, if used, is implemented in ROM to provide the Root of Trust for the Application Processor (AP).
An alternative flow is for a separate "security processor" to authenticate the AP firmware before the AP is released from reset. In such a flow, there is no need for BL1 and BL2 since that functionality is provided by the security processor. In such a flow, the TF-A RESET_TO_BL31 config can be used (see in-source documentation).
A TPM can provide additional security by storing secrets not even visible to TrustZone software (e.g. root keys or boot measurements). However, TPMs typically don't do firmware authentication on their own; some other software will need to use the secrets it stores, e.g. boot firmware may ask the TPM verify a signature corresponding to the next boot stage.
> If the TPM is changed to another, is the boot performed?
That depends on your system design.
Dan.
> -----Original Message-----
> From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org<mailto:tf-a-bounces@lists.trustedfirmware.org>> On Behalf Of Iñigo
> Vicente Waliño via TF-A
> Sent: 08 January 2020 10:33
> To: tf-a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org>
> Subject: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
>
> Hi,
>
> Does ARMv8 TrustZone provide BL1 in a secure ROM? Can a TPM be used as a
> trusted root or is it useless?
> If the TPM is changed to another, is the boot performed?
>
> Thanks,
> Inigo.
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Hi Inigo
TrustZone is a trademark referring to the security extensions of the Arm architecture. That is separate to BL1, which is the first boot stage of Trusted Firmware-A (or some other equivalent boot firmware). The expectation is that BL1, if used, is implemented in ROM to provide the Root of Trust for the Application Processor (AP).
An alternative flow is for a separate "security processor" to authenticate the AP firmware before the AP is released from reset. In such a flow, there is no need for BL1 and BL2 since that functionality is provided by the security processor. In such a flow, the TF-A RESET_TO_BL31 config can be used (see in-source documentation).
A TPM can provide additional security by storing secrets not even visible to TrustZone software (e.g. root keys or boot measurements). However, TPMs typically don't do firmware authentication on their own; some other software will need to use the secrets it stores, e.g. boot firmware may ask the TPM verify a signature corresponding to the next boot stage.
> If the TPM is changed to another, is the boot performed?
That depends on your system design.
Dan.
> -----Original Message-----
> From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Iñigo
> Vicente Waliño via TF-A
> Sent: 08 January 2020 10:33
> To: tf-a(a)lists.trustedfirmware.org
> Subject: [TF-A] Does ARMv8 TrustZone provide a secure ROM?
>
> Hi,
>
> Does ARMv8 TrustZone provide BL1 in a secure ROM? Can a TPM be used as a
> trusted root or is it useless?
> If the TPM is changed to another, is the boot performed?
>
> Thanks,
> Inigo.
> --
> TF-A mailing list
> TF-A(a)lists.trustedfirmware.org
> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.
IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.
Hi,
Does ARMv8 TrustZone provide BL1 in a secure ROM? Can a TPM be used as a
trusted root or is it useless?
If the TPM is changed to another, is the boot performed?
Thanks,
Inigo.
Hi,
Does ARMv8 TrustZone provide BL1 in a secure ROM? Can a TPM be used as a
trusted root or is it useless?
If the TPM is changed to another, is the boot performed?
Thanks,
Inigo.
Hi Sumit,
On 1/8/20 7:09 AM, Sumit Garg via TF-A wrote:
> Hi Sandrine,
>
> On Fri, 20 Dec 2019 at 12:29, Sumit Garg <sumit.garg(a)linaro.org> wrote:
>>
>> Hi Sandrine,
>>
>> On Wed, 18 Dec 2019 at 21:07, Sandrine Bailleux
>> <Sandrine.Bailleux(a)arm.com> wrote:
>>>
>>> Hi Sumit,
>>>
>>> I've started providing some early review comments on your patches in
>>> Gerrit but these are mainly about implementation details. I would like
>>> to continue the higher-level design discussions here in parallel on the
>>> mailing list, if that's fine with you.
>>>
>>
>> Yes that's perfectly fine with me.
>>
>
> Do you have any further comments? As I have already incorporated most
> of the your comments related to design and implementation details in
> latest v4 patch-set [1].
>
> [1] https://review.trustedfirmware.org/q/topic:%22tbbr%252Ffw_enc%22+(status:op…
Apologies, with the Christmas break, I haven't had a chance to look at
your patches again. I will allocate some time for it this week and get
back to you.
Regards,
Sandrine
Hi Sumit,
I've started providing some early review comments on your patches in
Gerrit but these are mainly about implementation details. I would like
to continue the higher-level design discussions here in parallel on the
mailing list, if that's fine with you.
On 12/6/19 1:29 PM, Sumit Garg via TF-A wrote:
> Hi Sandrine,
>
> On Thu, 5 Dec 2019 at 20:31, Sandrine Bailleux
> <Sandrine.Bailleux(a)arm.com> wrote:
>>>> Also, I am still trying to get my head around how this would integrate
>>>> with a cryptographic engine where the key does not leave the chip. I can
>>>> imagine that we could get the address of the encrypted firmware image
>>>> from the FIP, pass that to a cryptographic engine, request it to decrypt
>>>> it and store the result somewhere in Trusted RAM. In this case, we
>>>> wouldn't call plat_get_fip_encryption_key(). Do you have any idea how we
>>>> would pull this off? Like how the different modules (IO layer, crypto
>>>> module, image parser module, ...) would integrate together?
>>>
>>> In this case, I would expect platform to provide key identifier rather
>>> than actual key as part of plat_get_fip_encryption_key() which is then
>>> passed onto auth_decrypt() that is implementation specific to
>>> cryptographic engine in similar terms as currently done for mbedTLS
>>> backend.
>>
>> Ah I see, so plat_get_fip_encryption_key() could return either the key
>> itself or a key identifier. Just like plat_get_rotpk_info() can return
>> either the key or a hash of it today. However, in the case of
>> plat_get_rotpk_info(), it also returns some flags indicating which one
>> it is. Don't we need something similar for
>> plat_get_fip_encryption_key()? How will the crypto module be able to
>> tell the difference between a key and a key ID otherwise? Or would you
>> expect a given crypto module backend to always use either keys or key
>> IDs, but not both?
>>
>
> It perfectly makes sense for crypto module backend to support both key
> ID and actual key. But I was thinking from use-case perspective that
> why would one like to expose key to the firmware if the crypto module
> could better protect it. And I could come up with one use-case where
> the SSK (burnt in SoC fuses) is provided as an actual key and BSSK
> (accessible only to crypto module) is provided via a key ID.
Yes, that makes sense to me.
> So yes I agree with you to provide additional flags field along with
> key buffer. Also, I think it makes sense to rename
> "plat_get_fip_encryption_key()" to "plat_get_fip_enc_key_info()".
Agree.
>>>> I have some concerns around the generation of the initialization vectors
>>>> in the encrypt_fw tool. Right now, IVs are simply a random sequence of
>>>> bytes (obtained through a call to OpenSSL's RAND_bytes() API). Now, I
>>>> would imagine that RAND_bytes() is typically based on a good random
>>>> number generator and thus will generate different sequences every time
>>>> it is called. At least, as long as it is called from the same machine
>>>> every time. But what if we encrypt a new FIP bundle from a different
>>>> machine, say in the context of a firmware update? Is it not possible
>>>> that it might choose the same IV out of bad luck?
>>>>
>>>> Perhaps that's an issue left to provisioning/manufacturing time and is
>>>> out of the scope here. But it worries me because AFAIU, the security of
>>>> AES-GCM is critically undermined if the same nonce is used multiple
>>>> times with the same key (see section 5.1.1. "Nonce reuse" in RFC 5116).
>>>> If the encryption key is the SSK (rather than the BSSK) then I guess the
>>>> probability is even higher, as it is shared amongst a class of devices.
>>>>
>>>
>>> Agree that "nonce" should be unique and using a random number
>>> generator available on build machine was an effort towards that. But
>>> thinking about the case that you have mentioned, I think we could have
>>> an optional user provided "nonce" as an input to "encrypt_fw" tool, so
>>> that the user is aware to randomly generate and provide a unique
>>> nonce.
>>
>> Yes, I like your suggestion of specifying the nonce to the tool. But I
>> think it should be the default behaviour then. You mention an *optional*
>> user-provided nonce, I would like to suggest we make this mandatory
>> instead. We could provide an option to request the tool to generate the
>> nonce, intended for development purposes.
>>
>
> Making nonce as default and mandatory command line option seems to be
> overkill for a user. It may also lead to unsafe practices of
> hardcoding a nonce in Makefile, shell scripts etc. So I think we
> should keep this as optional only for a narrow use-case where people
> might not trust uniqueness property of RNG from multiple build
> machines.
I don't know... Hard-coding a nonce in the makefile is unsafe for sure
but I would think that a nonce generated by the tool is also unsafe
without proper management of these nonces across keys and devices, but
in a much more subtle manner. I still think the nonce generation would
be better left outside of the scope of this tool.
> BTW, I have already added nonce command line option as part of v3
> patch-set [1]. Please have a look.
>
> [1] https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/2496/2..3
>
>>>> Impact on memory footprint and performance
>>>> ------------------------------------------
>>>>
>>>> Do you know what the performance impact is when this feature is enabled
>>>> in TF-A, to decrypt images at boot time? Obviously it depends on the
>>>> platform and whether there is a dedicated cryptographic engine, and I
>>>> suppose you cannot really get any relevant measurements out of QEMU but
>>>> I would be interested if you've got any rough numbers.
>>>
>>> Following are measurements based on qemu for mbedTLS software library
>>> based authenticated decryption:
>>>
>>> BL31 plain:
>>> NOTICE: Load image time: 137us, size: 28KB
>>> BL31 encrypted:
>>> NOTICE: Load image time: 3979us, size: 28KB
>>>
>>> BL32 plain:
>>> NOTICE: Load image time: 1791us, size: 360KB
>>> BL32 encrypted:
>>> NOTICE: Load image time: 36339us, size: 360KB
>>
>> Thanks. So it's a 29% increase for BL31 and 20% for BL32. I would have
>> naively expected similar percentages, any idea why we get such a
>> difference between BL31 and BL32? I am just curious. Maybe it's down to
>> how the crypto algorithm/mode of operation works under the hood?
>
> Yes this additional increase for BL31 seems to be due to one time
> initialization operations carried on first invocation of mbedTLS gcm
> APIs, especially time taken to generate AES tables (see call to
> aes_gen_tables() in mbedtls/library/aes.c +576).
Ah I see, thanks for the explanation.
Regarding the memory impact, given that it's adding quite a bit of code
and data (around 9KB for BL1 and 12KB for BL2 from what you were saying
in a previous email), I think we need to make this feature optional and
wrap it under a build flag. Not everyone will need to encrypt firmware
images, having only authentication is a valid use case as well. If I am
not mistaken, your patches right now unconditionally pull the mbedTLS
primitives into BL1 and BL2 (as long as TBBR is enabled of course).
As a matter of fact, I am not able to build BL1 on FVP platform with
your patches, presumably due to the unconditional size increase. The
following build command:
> make TRUSTED_BOARD_BOOT=1 ARM_ROTPK_LOCATION=devel_rsa
MBEDTLS_DIR=mbedtls bl1
... fails at link time:
aarch64-linux-gnu-ld.bfd: build/fvp/release/bl1/bl1.elf section
`xlat_table' will not fit in region `RAM'
aarch64-linux-gnu-ld.bfd: BL1's RW section has exceeded its limit.
aarch64-linux-gnu-ld.bfd: region `RAM' overflowed by 4096 bytes
Makefile:889: recipe for target 'build/fvp/release/bl1/bl1.elf' failed
Regards,
Sandrine
Hi
> -----Original Message-----
> From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Soby Mathew
> via TF-A
> Sent: 06 January 2020 12:34
> To: Olivier Deprez <Olivier.Deprez(a)arm.com>; tf-a(a)lists.trustedfirmware.org;
> Sheetal Tigadoli <sheetal.tigadoli(a)broadcom.com>
> Cc: nd <nd(a)arm.com>
> Subject: Re: [TF-A] [Question] Why are the log related macros defined in
> multiple of 10's
>
> > Hi All,
> >
> > I wanted to understand the reason behind defining LOG_LEVEL_* macros
> > as multiple of 10's, also same goes with LOG_MARKER_* macros.
> > If we set the LOG macros to 1,2,3 and so on, we can avoid the mod and
> > division operation when printing the msgs to console.
> >
> > Please let me your thoughts on this.
> >
> > Link to this question on Phabricator -
> > https://developer.trustedfirmware.org/T624
> >
> > Thanks
> > Sheetal
>
As Sandrine said in Phabricator, the reason was simply to leave space between the levels to allow adding intermediate levels without breaking compatibility. Compatibility was a possible concern if external tools used the log level and you only rebuilt some of the TF-A components (components could end up using different values). However, I suspect the actual level value is never emitted in practice (just the text prefix) so this may not be a real concern.
> Hi Sheetal
> I didn't quite get reason for the optimization from multiples of 10 to
> consecutive numbers. The mod operation you refer to are assertions which will
> be compiled out when DEBUG=0 or when ENABLE_ASSSERTIONS=0. Other than that
> there is a single divide by 10 operation within the default implementation of
> plat_log_get_prefix().
>
>
> If the logging utility is considered performance critical, removing the
> single divide by 10 will not result in any gain. Usually the bottleneck for
> logs are UART baudrates and the CPU spends most of time spinning in a wait
> loop for UART to be free. Hence I don't see any need for change for log
> levels macro if the intent is performance optimization.
>
+1. Unless there's an actual performance gain, this sounds like an unnecessary change.
Dan.
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On 06/01/2020 12:34, Soby Mathew via TF-A wrote:
>> Hi All,
>>
>> I wanted to understand the reason behind defining LOG_LEVEL_* macros as
>> multiple of 10's, also same goes with LOG_MARKER_* macros.
>> If we set the LOG macros to 1,2,3 and so on, we can avoid the mod and
>> division operation when printing the msgs to console.
>>
>> Please let me your thoughts on this.
>>
>> Link to this question on Phabricator -
>> https://developer.trustedfirmware.org/T624
>>
>> Thanks
>> Sheetal
>
> Hi Sheetal
> I didn't quite get reason for the optimization from multiples of 10 to
> consecutive numbers. The mod operation you refer to are assertions which
> will be compiled out when DEBUG=0 or when ENABLE_ASSSERTIONS=0. Other
> than that there is a single divide by 10 operation within the default
> implementation of plat_log_get_prefix().
>
>
> If the logging utility is considered performance critical, removing the
> single divide by 10 will not result in any gain. Usually the bottleneck
> for logs are UART baudrates and the CPU spends most of time spinning in
> a wait loop for UART to be free. Hence I don't see any need for change
> for log levels macro if the intent is performance optimization.
>
> Best Regards
> Soby Mathew
>
Hi Sheetal
There is some discussion related to this here :
https://github.com/ARM-software/tf-issues/issues/462 and see associated
issues and PRs for more details.
Best Regards
Soby Mathew
>> --
>> TF-A mailing list
>> TF-A(a)lists.trustedfirmware.org
>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>>
>
> Hi All,
>
> I wanted to understand the reason behind defining LOG_LEVEL_* macros as
> multiple of 10's, also same goes with LOG_MARKER_* macros.
> If we set the LOG macros to 1,2,3 and so on, we can avoid the mod and
> division operation when printing the msgs to console.
>
> Please let me your thoughts on this.
>
> Link to this question on Phabricator -
> https://developer.trustedfirmware.org/T624
>
> Thanks
> Sheetal
Hi Sheetal
I didn't quite get reason for the optimization from multiples of 10 to
consecutive numbers. The mod operation you refer to are assertions which
will be compiled out when DEBUG=0 or when ENABLE_ASSSERTIONS=0. Other
than that there is a single divide by 10 operation within the default
implementation of plat_log_get_prefix().
If the logging utility is considered performance critical, removing the
single divide by 10 will not result in any gain. Usually the bottleneck
for logs are UART baudrates and the CPU spends most of time spinning in
a wait loop for UART to be free. Hence I don't see any need for change
for log levels macro if the intent is performance optimization.
Best Regards
Soby Mathew
> --
> TF-A mailing list
> TF-A(a)lists.trustedfirmware.org
> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>
Hi Varun
Could you take a look at the Nvidia driver defect reported by the Coverity scan?
Regards.
Alexei.
________________________________
From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> on behalf of scan-admin--- via TF-A <tf-a(a)lists.trustedfirmware.org>
Sent: 03 January 2020 08:19
To: tf-a(a)lists.trustedfirmware.org <tf-a(a)lists.trustedfirmware.org>
Subject: [TF-A] New Defects reported by Coverity Scan for ARM-software/arm-trusted-firmware
Hi,
Please find the latest report on new defect(s) introduced to ARM-software/arm-trusted-firmware found with Coverity Scan.
1 new defect(s) introduced to ARM-software/arm-trusted-firmware found with Coverity Scan.
New defect(s) Reported-by: Coverity Scan
Showing 1 of 1 defect(s)
** CID 352832: Uninitialized variables (UNINIT)
/plat/nvidia/tegra/soc/t194/drivers/mce/nvg.c: 197 in nvg_update_ccplex_gsc()
________________________________________________________________________________________________________
*** CID 352832: Uninitialized variables (UNINIT)
/plat/nvidia/tegra/soc/t194/drivers/mce/nvg.c: 197 in nvg_update_ccplex_gsc()
191 ret = EINVAL;
192 } else {
193 nvg_set_request_data((uint64_t)TEGRA_NVG_CHANNEL_UPDATE_CCPLEX_GSC,
194 (uint64_t)gsc_idx);
195 }
196
>>> CID 352832: Uninitialized variables (UNINIT)
>>> Using uninitialized value "ret".
197 return ret;
198 }
199
200 /*
201 * Cache clean operation for all CCPLEX caches.
202 */
________________________________________________________________________________________________________
To view the defects in Coverity Scan visit, https://u2389337.ct.sendgrid.net/wf/click?upn=08onrYu34A-2BWcWUl-2F-2BfV0V0…
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Hi Sheetal,
Your remark/question makes sense.
The original requirement is described here: https://github.com/ARM-software/tf-issues/issues/232
We may get further update from Dan, but I sense this was to provision for intermediate log levels (as stated by Sandrine on phabricator).
Will you be able to submit a patch for this?
Regards,
Olivier.
________________________________________
From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> on behalf of Sheetal Tigadoli via TF-A <tf-a(a)lists.trustedfirmware.org>
Sent: 20 December 2019 15:48
To: tf-a(a)lists.trustedfirmware.org
Subject: [TF-A] [Question] Why are the log related macros defined in multiple of 10's
Hi All,
I wanted to understand the reason behind defining LOG_LEVEL_* macros as
multiple of 10's, also same goes with LOG_MARKER_* macros.
If we set the LOG macros to 1,2,3 and so on, we can avoid the mod and
division operation when printing the msgs to console.
Please let me your thoughts on this.
Link to this question on Phabricator -
https://developer.trustedfirmware.org/T624
Thanks
Sheetal
--
TF-A mailing list
TF-A(a)lists.trustedfirmware.org
https://lists.trustedfirmware.org/mailman/listinfo/tf-a
Hi All,
I wanted to understand the reason behind defining LOG_LEVEL_* macros as
multiple of 10's, also same goes with LOG_MARKER_* macros.
If we set the LOG macros to 1,2,3 and so on, we can avoid the mod and
division operation when printing the msgs to console.
Please let me your thoughts on this.
Link to this question on Phabricator -
https://developer.trustedfirmware.org/T624
Thanks
Sheetal
Hi All,
I wanted to understand the reason behind defining LOG_LEVEL_* macros as
multiple of 10's, also same goes with LOG_MARKER_* macros.
If we set the LOG macros to 1,2,3 and so on, we can avoid the mod and
division operation when printing the msgs to console.
Please let me your thoughts on this.
Link to this question on Phabricator -
https://developer.trustedfirmware.org/T624
Thanks
Sheetal
>
> Subject: [PATCH] rpi3/4: Add support for offlining CPUs
> From: Jan Kiszka <jan.kiszka(a)siemens.com>
>
> The hooks were populated but the power down left the CPU in limbo-land.
> What we need to do - until there is a way to actually power off - is to
> turn off the MMU and enter the spinning loop as if we were cold-booted.
> This allows the on-call to pick up the CPU again.
>
> Signed-off-by: Jan Kiszka <jan.kiszka(a)siemens.com>
> ---
> plat/rpi/common/rpi3_pm.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/plat/rpi/common/rpi3_pm.c b/plat/rpi/common/rpi3_pm.c
> index 8c2d070c4..2a6bf076b 100644
> --- a/plat/rpi/common/rpi3_pm.c
> +++ b/plat/rpi/common/rpi3_pm.c
> @@ -123,6 +123,15 @@ static void rpi3_pwr_domain_off(const psci_power_state_t *target_state)
> #endif
> }
>
> +void __dead2 plat_secondary_cold_boot_setup(void);
> +
> +static void __dead2
> +rpi3_pwr_domain_pwr_down_wfi(const psci_power_state_t *target_state)
> +{
> + disable_mmu_el3();
> + plat_secondary_cold_boot_setup();
> +}
> +
> /*******************************************************************************
> * Platform handler called when a power domain is about to be turned on. The
> * mpidr determines the CPU to be turned on.
> @@ -224,6 +233,7 @@ static void __dead2 rpi3_system_off(void)
> static const plat_psci_ops_t plat_rpi3_psci_pm_ops = {
> .cpu_standby = rpi3_cpu_standby,
> .pwr_domain_off = rpi3_pwr_domain_off,
> + .pwr_domain_pwr_down_wfi = rpi3_pwr_domain_pwr_down_wfi,
> .pwr_domain_on = rpi3_pwr_domain_on,
> .pwr_domain_on_finish = rpi3_pwr_domain_on_finish,
> .system_off = rpi3_system_off,
> --
> 2.16.4
>
Hi Jan,
I have put in a suggestion for the change. Basically, if you are able to
do a `reset` before spinning in `plat_secondary_cold_boot_setup()`, that
would be ideal. Also, if `plat_secondary_cold_boot_setup()` can trap the
primary CPU as well if it were to be offlined, then I think your changes
should be good.
Best Regards
Soby Mathew
Hi Jisheng,
This is due to the power management requirement of GICv3. In section 7.1 of GICv3 specification : https://static.docs.arm.com/ihi0069/c/IHI0069C_gic_architecture_specificati…
It says the that " Before powering down the CPU interface and the PE when the Redistributor is powered up, software must put the interface between the CPU interface and the Redistributor into the quiescent state or the system will become UNPREDICTABLE".
In order to put the Redistributor in a quiescent state, all the group enables in CPU interface must be disabled , otherwise "setting GICR_WAKER.ProcessorSleep to 1 when the physical group enables in the CPU interface are set to 1 results in UNPREDICTABLE behavior."
Hope that clarifies.
Best Regards
Soby Mathew
> -----Original Message-----
> From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Jisheng
> Zhang via TF-A
> Sent: 05 December 2019 10:31
> To: tf-a(a)lists.trustedfirmware.org
> Subject: [TF-A] About disable gic cpuif in psci suspend or off
>
> Hi,
>
> In ATF-A, I usually see below code in psci suspend or off code path:
>
> /* Prevent interrupts from spuriously waking up this cpu */
> plat_arm_gic_cpuif_disable();
>
> But per my understanding, before calling psci_suspend(), the NW, e.g linux
> kernel has disabled all interrupts from cpu level, so here preventing interrupt is
> to prevent the interrupts from secure world?
>
> Another question is: for Cortex A55, this is not necessary. Because
> CA55 TRM says when the core_pwrdn_en bit is set, executing WFI
> automatically masks all interrupts and wake-up events in the core. Am I right?
>
> Thanks in advance
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