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d95d56bd2b
The problem that this resolves is a bit involved; the following
must be met at the same time for some function <to_be_wrapped>:
* to_be_wrapped must be specified as part of the romlib
* to_be_wrapped must _not_ be referenced by any translation unit
in TF-A
* to_be_wrapped must be referenced by a translation unit in a
dependent library, mbedtls for example.
Under these circumstances, to_be_wrapped will not be wrapped, and
will instead reference its original definition while simultaneously
residing in romlib.
This is a side effect of two issues with romlib prior to this patch:
1 to_be_wrapped is expected to wrap by duplicating its definition.
This causes any condition that links against both the base and
wrapper functions to be a link error (duplicate symbol definition).
2 to_be_wrapped is in its own translation unit
This causes the wrappers to be used by TF-A in an as needed.
The duplicate function definitions can be worked around using the
linker's `--wrap` flag, which redirects all references to a symbol
to resolve to `__wrap_<symbol>` and the original symbol to be
available as `__real_<symbol>`. Most of the changes handle creating
this arguments and passing them to the linker.
Further, once you use the linker's wrap, you will encounter another
issue: if TF-A does not use a function, its wrapper is not present.
This causes link issues when a library and not TF-A uses the wrapper.
Note that this issue would have been resolved previously by ignoring
the wrapper and using the base definition.
This further issue is worked around by concatenating the assembly for
all of the wrappers into a single translation unit. It's possible to
work around this issue in a few other ways, including reordering the
libraries passed to the linker to place libwrapper.a last or grouping
the libraries so that symbols from later libraries may be resolved
with prior libraries.
I chose the translation unit concatenation approach as it revealed
that a jumptable has duplicate symbols within it.
Change-Id: Ie57b5ae69bde2fc8705bdc7a93fae3ddb5341ed9
Signed-off-by: Jimmy Brisson <jimmy.brisson@arm.com>
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Trusted Firmware-A ================== Trusted Firmware-A (TF-A) is a reference implementation of secure world software for `Arm A-Profile architectures`_ (Armv8-A and Armv7-A), including an Exception Level 3 (EL3) `Secure Monitor`_. It provides a suitable starting point for productization of secure world boot and runtime firmware, in either the AArch32 or AArch64 execution states. TF-A implements Arm interface standards, including: - `Power State Coordination Interface (PSCI)`_ - `Trusted Board Boot Requirements CLIENT (TBBR-CLIENT)`_ - `SMC Calling Convention`_ - `System Control and Management Interface (SCMI)`_ - `Software Delegated Exception Interface (SDEI)`_ The code is designed to be portable and reusable across hardware platforms and software models that are based on the Armv8-A and Armv7-A architectures. In collaboration with interested parties, we will continue to enhance TF-A with reference implementations of Arm standards to benefit developers working with Armv7-A and Armv8-A TrustZone technology. Users are encouraged to do their own security validation, including penetration testing, on any secure world code derived from TF-A. More Info and Documentation --------------------------- To find out more about Trusted Firmware-A, please `view the full documentation`_ that is available through `trustedfirmware.org`_. -------------- *Copyright (c) 2013-2019, Arm Limited and Contributors. All rights reserved.* .. _Armv7-A and Armv8-A: https://developer.arm.com/products/architecture/a-profile .. _Secure Monitor: http://www.arm.com/products/processors/technologies/trustzone/tee-smc.php .. _Power State Coordination Interface (PSCI): PSCI_ .. _PSCI: http://infocenter.arm.com/help/topic/com.arm.doc.den0022d/Power_State_Coordination_Interface_PDD_v1_1_DEN0022D.pdf .. _Trusted Board Boot Requirements CLIENT (TBBR-CLIENT): https://developer.arm.com/docs/den0006/latest .. _SMC Calling Convention: http://infocenter.arm.com/help/topic/com.arm.doc.den0028b/ARM_DEN0028B_SMC_Calling_Convention.pdf .. _System Control and Management Interface (SCMI): SCMI_ .. _SCMI: http://infocenter.arm.com/help/topic/com.arm.doc.den0056a/DEN0056A_System_Control_and_Management_Interface.pdf .. _Software Delegated Exception Interface (SDEI): SDEI_ .. _SDEI: http://infocenter.arm.com/help/topic/com.arm.doc.den0054a/ARM_DEN0054A_Software_Delegated_Exception_Interface.pdf .. _Arm A-Profile architectures: https://developer.arm.com/architectures/cpu-architecture/a-profile .. _view the full documentation: https://www.trustedfirmware.org/docs/tf-a .. _trustedfirmware.org: http://www.trustedfirmware.org