Hi,
Trusted OSes such as OP-TEE or QSEE are using SMC yielding function
numbers in the 0x32000000-0x3200006F range. The SMC calling
conventions are specified in DEN0028 which has currently three
versions (see below).
To the best of my understanding, the use of this range is:
- compliant with version a
- acceptable with version b
- somewhat contradicting with version c
version a analysis:
table 6.1 states that the trusted OS standard calls should be in the
range "0x02000000-0x7FFFFFFF", so the selected range is good. Section
2.1 that defines a bit structure for function numbers for both
yielding and fast calls and the range is compatible. The range covered
by table 6.1 for Trusted OS calls is however much bigger that the bit
structure definition. As a result a 0x02000000 call is a yielding
Trusted OS call as per table 6.1 but a Yielding SiP call as per
section 2.1.
version b analysis:
table 6.2 states that the trusted OS yielding calls should be in the
range "0x02000000-0x1FFFFFFF" and that the range
"0x20000000-0x7FFFFFFF" is "reserved for future expansion of Trusted
OS Yielding Calls". So the range is acceptable but poorly selected.
There is the same inconsistency as version a when it comes to
qualifying a 0x02000000 call: table 6.2 says it is a Trusted OS
yielding call, section 2.5 says it is a yielding SiP call.
version c analysis:
section 2.5.1 now clearly states that the bit structure is only for
Fast calls. and both section 2.52 and table 6.2 state that Trusted OS
calls should be in the range "0x02000000-0x1FFFFFFF". both section
2.5.2 and 6 qualify the 0x02000000 call as a Trusted OS yielding
call.
I think that version a and b have inconsistent between chapter 2 and
6. Version c brings internal consistency but seems to be not in
alignment with best practices.
I guess there is a need to both address internal document
inconsistency and better reflect existing products.
Any thoughts?
-FF
version a:
https://drive.google.com/file/d/1OclQZk0o28n5ZUIYeTuFICbLiGWzOvxH/view?usp=…
version b: https://static.docs.arm.com/den0028/b/ARM_DEN0028B_SMC_Calling_Convention.p…
version c:
https://static.docs.arm.com/den0028/c/Q1-ARM-DEN-0028_SMC_Calling_Conventio…
On Wed, Mar 11, 2020 at 01:42:36PM +0100, Francois Ozog wrote:
> On Wed, 11 Mar 2020 at 12:45, Daniel Thompson <daniel.thompson(a)linaro.org>
> wrote:
>
> > On Wed, Mar 11, 2020 at 11:20:17AM +0100, Francois Ozog wrote:
> > > On Wed, 11 Mar 2020 at 07:48, Heinrich Schuchardt <xypron.glpk(a)gmx.de>
> > wrote:
> > > > On 3/11/20 12:04 AM, Heinrich Schuchardt wrote:
> > > > In the expert mode of gdisk there is command 'j' for moving the GPT
> > > > Partition Entry Array to an arbitrary sector. This will protect the
> > area
> > > > between the GPT header and the GPT Partition Entry Array from being
> > used
> > > > for a partition. The same can be done with parameter -j of sgdisk.
> > > >
> > > > Furthermore gdisk supports creating a hybrid MBR. This allow to have
> > > > GUID partition table and a MBR partion table at the same time where the
> > > > MBR partition table mirrors up to three GPT partitions and the fourth
> > > > MBR partition is used to protect the GUID partition table.
> > > >
> > > > So requiring GPT and having boards only supporting booting from an MBR
> > > > partition (like the Raspberry) seems not to be exclusive.
> > > >
> > >
> > > That sounds like a great solution!
> >
> > The last time we discussed this there was *very* strong opposition
> > during meetings to hybrid partitioning and IIRC language was added to
> > the spec to prohibit it.
> >
> > Hybrid partitioning is a problem because it imposes to difficult to meet
> > constraints on partitioning tools provided by the operating system.
> >
> > In other words if we permit hybrid partitioning in order that boot code
> > can find the firmware then the operating system would inherit a duty to
> > not to screw up the firmware loading when it modifies the partition
> > tables. It is hard to express how the OS should go about that.
> >
> > Hence the current approach where we accept that MBR partitioning
> > offers an inferior feature set to GPT.
> >
> >
> We have the following cases:
>
> - FW compatible with GPT (I mean firmware can be searched based on
> GUID partition)
> Ok
>
> - FW that uses offsets and can be positioned at LBA >= 33
> Ok
> Need to define a protective partition
>
> - FW that uses offsets and can be positioned such that space between LBA-2
> and LBA-33 is used.
> Ok in theory as the header states where the partition entries location is
> specified in a GPT_HEADER "Starting LBA of array of partition entries".
> Linux kernel properly loads the partition entries if we push them after
> 16MB.
>
> read_lba <https://elixir.bootlin.com/linux/latest/ident/read_lba>(state,
> le64_to_cpu <https://elixir.bootlin.com/linux/latest/ident/le64_to_cpu>(gpt->partition_entry_lba)
>
> But I bet 2 is hardcoded in many tools...
Agree... but that's "just bugs" and I suspect we could get >90% test
coverage for Linux systems just by checking util-linux (and the kernel
itself). Maybe for extra style points also check on of the BSDs.
> - FW that supposes LBA-1 (macchiatobin the firmware blob that contain TF-A
> must be here)
> In theory OK as Linux will detect bad signature and use the alternate GPT
In the current spec this case isn't materially different to firmware
whose boot ROM parses the MBR to load extra code (which wasn't listed
above). In both cases the system would be expected to adopt MBR and
create protective partitions for the firmware (and accept that the
protective partition is vulnerable to damage by auto-partitioning
installers).
Having said is this really relevant for MacchiatoBin? Why put EBBR
firmware onto shared media? I thought MacchiatoBin could boot from the
4MB SPI NOR.
Daniel.
Hi,
I have observed a spike in DT presentations at events in 2018 and a
relative smaller set in 2019.
Many discussions raise a lot of good points, there are lists of things
to solve or proposals in various sites but there is no clear path to a
widely acceptable solution.
It feels like the traditional model of "contribute code first" reaches
its limits here: Device Tree is not just a device tree. It is a
pivotal piece of information manipulated by too many components from
Trusted Firmware A to Mac OSX and U-boot. And there are many
legitimate "owners" of pieces of the DT...
We need to find a way to build consensus across projects. Mail
discussions are good but I feel this does not fully help getting
closer to having up streamed code and specs into projects such as (and
not limited to):
- Trusted Firmware
- OP-TEE
- Hafnium
- U-Boot
- Linux
- Android
- FreeBSD
- DeviceTree
- EBBR
- Firmware Framework A
- Parsec
To that end, what about collectively building a Technical Report with
a number of editors in charge of different sections?
An example outline could be:
- the problems we try to solve (and what is outside of scope)
. board diversity handling (build/boot/runtime)
. cape/hat/FPGA handling (build/boot/runtime)
. product value chain handling (soc vendor/product vendor/sw vendor...)
. trust of DT
. device assignment to application or VM
- DT evolution
. actors (UML meaning)
. responsibility boundaries (signatures...)
. DTB format evolution
. DTBo
. DT at build time for many upstream projects
- cross project incremental roadmap highlights
. introduce DT signature
Of course the Technical Report shall be supported by different PoCs on
many topics such as DTB format so that the architecture is future
proof and we can start small.
What are your views?
Cheers
FF
Hi,
Following implementation (or work towards) of EBBR 1.0 + UEFI Secure
boot + UEFI update capsule we learnt a lot.
Here are some topics that may need some clarification on the EBBR
specs and It looks timely to start working on EBBR evolution.
0.1 - EBBR goal
May be a reassessment on the "for what" the specification is built.
Following all the discussions with prominent industry players, I start
to think that limiting the constraints to be EBBR compliant may become
counter productive. There will be both EBBR non compliant and EBBR
compliant systems. This is inevitable. But EBBR exist for a number of
use cases in a number of markets. The value of EBBR is consistent
behavior across those.
Maximising number of EBBR compliant systems without stating use case
parameters ( "why" and "for what") may not be the best goal.
Out of things to be more explicit are supported secure boot flows
(with/without shim+grub or direct). Some vendors require shim+grub
while industry players want the exact opposite: nothing but UEFI. This
drivers a number of requirements in terms of UEFI protocols needed
0.2 - normative text
The normative section shall be stated clearly: is " 1.2. Guiding
Principles" normative?
IETF and ETSI have different language conventions to express
absolutely mandated and various levels of optionality. This spec may
be red by Telecom people or Linux people. Their interpretation may be
erroneous on words such as "shall" (ETSI "SHALL" = "IETF "MUST"). The
language need to be explicit.
I - protective offsets
EBBR 1.0 states in "4.1. Partitioning of Shared Storage" that
"Automatic partitioning tools (e.g. an OS installer) must not create
partitions within the first 1MiB of storage, or delete, move, or
modify protective partition entries."
StandaloneMM is 2.5MB by itself with U-Boot being over 1MB without the
variable rework done and update capsules. 4MB seems the minimum. 8MB
to get margin and 16MB for A/B scheme.
EBBR same paragraph also states:
"Automatic partitioning tools (e.g. an OS installer) must not create
partitions within the first 1MiB of storage, or delete, move, or
modify protective partition entries. Manual partitioning tools should
provide warnings when modifying protective partitions or creating
partitions within the first 1MiB."
is it expected that Linaro upstreams changes in installation tools,
partition tools to conform to this (with updated to be agreed
minimum)?
II - identifying partitions
Having two EFI partitions defined with EFI_GUID need a precise
behaviour defined: boot with first or boot with second.
Shall we have a EFI_GUID_ALT defined for A/B partition schemes?
If not, the BootXXX variables should be used as selector?
We lean towards BootXXX variables and not defining a new GUID. But
this would mean explicit behavior to be stated in case of lack of
BootXXX.
I think GPT volume mirroring should be used in conjunction with A/B:
A/B to recover version failures with current hardware, surrounding
software; mirroring to protect against storage failures.
Is there any recommendation on mirrored EFI volumes handling ?
III - 32 bits
are there any 32 bits specific considerations to be added?
IV - UEFI_RNG_PROTOCOL
Following my view in 0) I think this shall be made mandatory
Linaro has upstreamed this in U-Boot and started to implement
additional hardware drivers.
KASLR is thus functional in 64 bits and will be in 32bits.
V - UEFI SecureBoot
Following my view in 0) I think this shall be made mandatory
UEFI SecureBoot is not mentioned in section 2.6 so we need to clarify
what needs to be implemented.
In particular, we need to implement EFI_LOAD_FILE2_PROTOCOL for initrd
signature checking.
VI - UEFI update capsules
Following my view in 0) I think this shall be made mandatory
Section 2.6 of UEFI spec 2.7 mentions
At some point in time we will need to propose UEFI specification update for:
- anti-bricking anti rollback expected behavior
- abstract capsules for "start transaction", "commit", "rollback" when
we will be dealing with system wide transactional updates.
There is probably a lot to state here but I am just starting the discussion.
VII - UEFI watchdog
Following my view in 0) I think this shall be made mandatory
In addition to its definition, it should also integrate consistent
parameters to define total duration covered as well as number of
failed consecutive updates to be triggered as well as how it is
delivered (powercycle, NMI, secureIRQ...)
Cheers
--
François-Frédéric
Hello Francois,
in a previous post I already mentioned some device tree fix-ups that
U-Boot is applying.
One new fix-up I found is the "cpu-release-addr" property in CPU nodes
if the "enable-method" is "spin-table". - Before seeing this I never
imagined CPU nodes to be dynamically filled.
I think for our DTE discussion on signed device trees it would be
valuable to know which parts of the device-tree are dynamically created.
Where would be a good location to collect this information?
Would the topic of dynamic parts of device trees deserve two slides on
our next meeting?
Best regards
Heinrich
On 5/20/20 7:49 PM, François Ozog wrote:
>
>
> On Wed, 20 May 2020 at 19:30, Daniel Thompson
> <daniel.thompson(a)linaro.org <mailto:daniel.thompson@linaro.org>> wrote:
>
> On Wed, May 20, 2020 at 07:00:53PM +0200, François Ozog wrote:
> > On Wed, 20 May 2020 at 18:39, Daniel Thompson
> <daniel.thompson(a)linaro.org <mailto:daniel.thompson@linaro.org>>
> > wrote:
> >
> > > On Tue, May 19, 2020 at 03:29:01PM +0100, Grant Likely wrote:
> > > > On 11/03/2020 16:42, Daniel Thompson wrote:
> > > > > On Wed, Mar 11, 2020 at 01:42:36PM +0100, Francois Ozog wrote:
> > > > > > We have the following cases:
> > > > > >
> > > > > > - FW compatible with GPT (I mean firmware can be searched
> based on
> > > > > > GUID partition)
> > > > > > Ok
> > > > > >
> > > > > > - FW that uses offsets and can be positioned at LBA >= 33
> > > > > > Ok
> > > > > > Need to define a protective partition >>
> > > > > > - FW that uses offsets and can be positioned such that
> space between
> > > LBA-2
> > > > > > and LBA-33 is used.
> > > > > > Ok in theory as the header states where the partition entries
> > > location is
> > > > > > specified in a GPT_HEADER "Starting LBA of array of partition
> > > entries".
> > > > > > Linux kernel properly loads the partition entries if we
> push them
> > > after
> > > > > > 16MB.
> > > > > >
> > > > > > read_lba
> <https://elixir.bootlin.com/linux/latest/ident/read_lba
> > > >(state,
> > > > > > le64_to_cpu <
> > > https://elixir.bootlin.com/linux/latest/ident/le64_to_cpu
> > > >(gpt->partition_entry_lba)
> > > > > >
> > > > > > But I bet 2 is hardcoded in many tools...
> > > > >
> > > > > Agree... but that's "just bugs" and I suspect we could get
> >90% test
> > > > > coverage for Linux systems just by checking util-linux (and
> the kernel
> > > > > itself). Maybe for extra style points also check on of the BSDs.
> > > >
> > > > It is worth stepping back from the details to take a look at
> the intent.
> > > The
> > > > purpose of this entire section of EBBR is to describe how
> firmware and
> > > the
> > > > OS can co-exist on the same media device. In broad strokes it
> means if
> > > > firmware is stored on the block device, then the OS must
> constrain how it
> > > > uses the device.
> > > >
> > > > On platforms with separate firmware storage (e.g., SPI flash
> or UFS boot
> > > > partitions) this isn't an issue. The OS can blow away
> everything on the
> > > disk
> > > > and recreate it.
> > > >
> > > > But when it is an issue, the rules need to lay down what regions
> > > (offsets,
> > > > partitions, or file paths) firmware is allowed to own and what
> the OS is
> > > and
> > > > is not allowed to do. e.g., the OS is allowed to erase and
> recreate the
> > > OS
> > > > partitions, but it is not allowed to write a blank GPT or
> erase the
> > > system
> > > > partition.
> > > >
> > > > I think the EBBR spec should focus on defining exactly what
> restrictions
> > > on
> > > > the OS are, and how the restrictions are communicated. Then OS
> vendors
> > > have
> > > > a fighting chance of supporting the restricted platforms well.
> > > >
> > > > Ultimately though this is a guide and the OS could choose to
> ignore the
> > > > restrictions... in which case it gets to keep the unbootable
> brick when
> > > it
> > > > does. :-)
> > >
> > > Agree with all above.
> > >
> > > Also I think we can turn at least part of the original issue into a
> > > concrete question.
> > >
> > > We have a SOC with some magic values hard coded into its boot
> ROM. The
> > > System Firmware author wants to ship it with the following GPT
> on the
> > > shared eMMC.
> > >
> > > LBA0 Protective MBR
> > > LBA1 Primary GPT header
> > > LBA2..18001 Reserved, mixture of dead space and a system firmware
> > > loaded by Boot rom
> > > LBA18002 Start of partition arrray (Entry 1, 2, 3, 4)
> > > ...
> > > LBA18033 End of partition arrray
> > > LBA18034 Start of allocatable partition space
> > > LBA-33..-1 End of disk is labelled as normal
> > >
> > > (or in a shorter GPT jargon form, a system where
> PartitionEntryLBA is
> > > 18002).
> > >
> > > Is such a system EBBR compliant? If yes, should it be?
> > >
> > > I would say it is not EBBR compliant because it does not follow
> EFI spec
> > and we mandate it in EBBR.
>
> Sure, if there is language in the EFI spec that prohibits this then the
> answer is a no brainer.
>
> Assuming you've found such language could you quote your references? ;-)
>
> Oups! I thought of GPT Header being at 18002.....
> as you push the firstUsableLBA... it seems to be valid in that EFI
> compliant and hence EBBR compliant ;-)
>
> That said to get the GPT Partition move, the spec patch to table 20 is
> not impressive:
> image.png
> - set to 0x000001 (ie...
> + the LBA to the GPT partition header
The position of the GPT *HEADER* in Daniel's example is LBA 1 and should
not be changed to stay UEFI compliant.
Daniel moved the first GPT *TABLE* whose position is defined in the GPT
header and this is UEFI compliant.
Best regards
Heinrich
>
>
> Daniel.
>
>
> > Is the use case "valid"? I think it is valid because when you deal
> with
> > immutable BootROM you don't want complex code, GPT may evolve so
> that you
> > would have to evolve the BootROM...
> > If we conclude this is a valid use case (and not creating ugly
> legacy to
> > deal with in the future), we need a clean reservation in EFI so
> that GPT
> > can start at an arbitrary LBA as 18002.
> > enhancing the protective MBR semantics does not seem too complex to
> > achieve.
> > Can we list SoCs that have similar characteristic?
> >
> > >
> > > Daniel.
> > >
> > >
> > > PS 18002 is arbitrary but I think the example is sufficient in this
> > > form and it was easier to diagram with a concrete number.
> > >
> >
> >
> > --
> > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group*
> > T: +33.67221.6485
> > francois.ozog(a)linaro.org <mailto:francois.ozog@linaro.org> |
> Skype: ffozog
>
>
>
> --
>
> François-Frédéric Ozog | /Director Linaro Edge & Fog Computing Group/
> T: +33.67221.6485
> francois.ozog(a)linaro.org <mailto:francois.ozog@linaro.org> | Skype: ffozog
>
>
Hi,
yet another email to spam you more....
I propose to have an Android DT overlay presentation next call and add
topics that may arise from the list. Should you think we should
discuss a particular topic, please respond to this mail thread.
Cordially,
Francois-Frederic
Hi,
Please find below the May 27th agenda:
- Project overall: FF (5 minutes)
- EBBR spec / DT stuff advances (mail thread): Grant (10 minutes)
- dynamic parts of device trees presentation: Heinrich (30 minutes)
- DTviewer presentation and demo: CVS (15 minutes)
Scratch pad notes and agenda can be found here:
https://docs.google.com/document/d/1GfYYph_XKt1LHuCs1w9kjvyyYYw1R7AH3dlZwIX…
--
FF
PS: I bcc'ed different lists until we have everyone on the
boot-architecture mailing list. Please make sure you are on this list.
The work addressed in DT Evolution project spans many operating
systems, boot firmwares, trust environments and processor
architectures.
UEFI 2.8 Errata A changed RuntimeServiceSupported value to be passed via
an EFI_RT_PROPERTIES_TABLE instead of via a runtime variable.
This is a breaking change and we should do a new EBBR release in short
order to keep EBBR up to date with what is in UEFI. However, real world
impact is minimal. U-Boot has already converted to the new method, and
Linux only ever implemented the EFI_RT_PROPERTIES_TABLE method.
Cc: Andrei Warkentin <awarkentin(a)vmware.com>
Cc: Francois Ozog <francois.ozog(a)linaro.org>
Cc: Ard Biesheuvel <ardb(a)kernel.org>
Signed-off-by: Grant Likely <grant.likely(a)arm.com>
---
source/chapter2-uefi.rst | 7 ++++---
source/references.rst | 6 +++---
2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/source/chapter2-uefi.rst b/source/chapter2-uefi.rst
index 82b1a42..c42691b 100644
--- a/source/chapter2-uefi.rst
+++ b/source/chapter2-uefi.rst
@@ -9,7 +9,7 @@ platforms.
UEFI Version
============
-This document uses version 2.8 of the UEFI specification [UEFI]_.
+This document uses version 2.8 Errata A of the UEFI specification [UEFI]_.
UEFI Compliance
===============
@@ -111,7 +111,7 @@ during both boot services and runtime services.
However, it isn't always practical for all EFI_RUNTIME_SERVICES functions
to be callable during runtime services due to hardware limitations.
If any EFI_RUNTIME_SERVICES functions are only available during boot services
-then firmware shall provide the global `RuntimeServicesSupported` variable to
+then firmware shall provide the `EFI_RT_PROPERTIES_TABLE` to
indicate which functions are available during runtime services.
Functions that are not available during runtime services shall return
EFI_UNSUPPORTED.
@@ -202,7 +202,8 @@ If a platform does not implement modifying non-volatile variables with
SetVariable() after ExitBootServices(),
then firmware shall return EFI_UNSUPPORTED for any call to SetVariable(),
and must advertise that SetVariable() isn't available during runtime services
-via the `RuntimeServicesSupported` variable as defined in [UEFI]_ § 8.1.
+via the `RuntimeServicesSupported` value in the `EFI_RT_PROPERTIES_TABLE`
+as defined in [UEFI]_ § 4.6.
EFI applications can read `RuntimeServicesSupported` to determine if calls
to SetVariable() need to be performed before calling ExitBootServices().
diff --git a/source/references.rst b/source/references.rst
index d901bb1..1eb0509 100644
--- a/source/references.rst
+++ b/source/references.rst
@@ -20,6 +20,6 @@
<https://static.docs.arm.com/den0044/b/DEN0044B_Server_Base_Boot_Requirement…>`_
8 March 2016, `Arm Limited <http://arm.com>`_
-.. [UEFI] `Unified Extensable Firmware Interface Specification v2.8
- <http://www.uefi.org/sites/default/files/resources/UEFI_Spec_2_8_final.pdf>`_,
- March 2019, `UEFI Forum <http://www.uefi.org>`_
+.. [UEFI] `Unified Extensable Firmware Interface Specification v2.8 Errata A
+ <https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_A_Feb14.pdf>`_,
+ February 2020, `UEFI Forum <http://www.uefi.org>`_
--
2.20.1
Hi all,
I'm considering doing a quick point-release for EBBR to address the
change to RuntimeServicesSupported in UEFI 2.8 Errata A. From 2.8final
to 2.8_A, RuntimeServicesSupported changed from being a variable to data
in a system table entry. U-Boot and Linux have been updated to the UEFI
method. EBBR needs to be changed to match.
There are patches on this list under discussion now. Once that is
complete and the patches merged, how does everyone feel about an EBBR
v1.0.1 release before the end of May?
At this moment, the v1.0.1 changes would include:
e47952b (HEAD -> master, glikely/master) Specify details of how a DTB is
passed to the OS
c155e96 Update spec to address UEFI 2.8 Errata A
7fad894 (origin/master, origin/HEAD) Fix all UEFI references to be the
same version
498cad2 trivial: Fix typo in chater 3 title
2c40029 Merge pull request #43 from orangecms/link-to-linux-doc
1e51a1e Update link to Linux docs which changed to rst
be7ddfa Update CONTRIBUTING.rst
763aed0 Update CONTRIBUTING.rst
All of the above can be found queued up at http://github.com/glikely/ebbr
g.
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