a1781a211a
Invalidate the Branch Target Buffer (BTB) on entry to EL3 by temporarily dropping into AArch32 Secure-EL1 and executing the `BPIALL` instruction. This is achieved by using 3 vector tables. There is the runtime vector table which is used to handle exceptions and 2 additional tables which are required to implement this workaround. The additional tables are `vbar0` and `vbar1`. The sequence of events for handling a single exception is as follows: 1) Install vector table `vbar0` which saves the CPU context on entry to EL3 and sets up the Secure-EL1 context to execute in AArch32 mode with the MMU disabled and I$ enabled. This is the default vector table. 2) Before doing an ERET into Secure-EL1, switch vbar to point to another vector table `vbar1`. This is required to restore EL3 state when returning from the workaround, before proceeding with normal EL3 exception handling. 3) While in Secure-EL1, the `BPIALL` instruction is executed and an SMC call back to EL3 is performed. 4) On entry to EL3 from Secure-EL1, the saved context from step 1) is restored. The vbar is switched to point to `vbar0` in preparation to handle further exceptions. Finally a branch to the runtime vector table entry is taken to complete the handling of the original exception. This workaround is enabled by default on the affected CPUs. NOTE ==== There are 4 different stubs in Secure-EL1. Each stub corresponds to an exception type such as Sync/IRQ/FIQ/SError. Each stub will move a different value in `R0` before doing an SMC call back into EL3. Without this piece of information it would not be possible to know what the original exception type was as we cannot use `ESR_EL3` to distinguish between IRQs and FIQs. Change-Id: I90b32d14a3735290b48685d43c70c99daaa4b434 Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com> |
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readme.rst
ARM Trusted Firmware - version 1.4
ARM Trusted Firmware provides a reference implementation of secure world software for ARMv8-A, including a Secure Monitor executing at Exception Level 3 (EL3). It implements various ARM interface standards, such as:
- The Power State Coordination Interface (PSCI)
- Trusted Board Boot Requirements (TBBR, ARM DEN0006C-1)
- SMC Calling Convention
- System Control and Management Interface
As far as possible the code is designed for reuse or porting to other ARMv8-A model and hardware platforms.
ARM will continue development in collaboration with interested parties to provide a full reference implementation of Secure Monitor code and ARM standards to the benefit of all developers working with ARMv8-A TrustZone technology.
License
The software is provided under a BSD-3-Clause license. Contributions to this project are accepted under the same license with developer sign-off as described in the Contributing Guidelines.
This project contains code from other projects as listed below. The original license text is included in those source files.
- The stdlib source code is derived from FreeBSD code, which uses various BSD licenses, including BSD-3-Clause and BSD-2-Clause.
- The libfdt source code is dual licensed. It is used by this project under the terms of the BSD-2-Clause license.
- The LLVM compiler-rt source code is dual licensed. It is used by this project under the terms of the NCSA license (also known as the University of Illinois/NCSA Open Source License).
This Release
This release provides a suitable starting point for productization of secure world boot and runtime firmware, in either the AArch32 or AArch64 execution state.
Users are encouraged to do their own security validation, including penetration testing, on any secure world code derived from ARM Trusted Firmware.
Functionality
- Initialization of the secure world, for example exception vectors, control registers and interrupts for the platform.
- Library support for CPU specific reset and power down sequences. This includes support for errata workarounds and the latest ARM DynamIQ CPUs.
- Drivers to enable standard initialization of ARM System IP, for example Generic Interrupt Controller (GIC), Cache Coherent Interconnect (CCI), Cache Coherent Network (CCN), Network Interconnect (NIC) and TrustZone Controller (TZC).
- A generic SCMI driver to interface with conforming power controllers, for example the ARM System Control Processor (SCP).
- SMC (Secure Monitor Call) handling, conforming to the SMC Calling Convention using an EL3 runtime services framework.
- PSCI library support for CPU, cluster and system power management use-cases. This library is pre-integrated with the AArch64 EL3 Runtime Software, and is also suitable for integration with other AArch32 EL3 Runtime Software, for example an AArch32 Secure OS.
- A minimal AArch32 Secure Payload (SP_MIN) to demonstrate PSCI library integration with AArch32 EL3 Runtime Software.
- Secure Monitor library code such as world switching, EL1 context management and interrupt routing. When a Secure-EL1 Payload (SP) is present, for example a Secure OS, the AArch64 EL3 Runtime Software must be integrated with a dispatcher component (SPD) to customize the interaction with the SP.
- A Test SP/SPD to demonstrate AArch64 Secure Monitor functionality and SP interaction with PSCI.
- SPDs for the OP-TEE Secure OS, NVidia Trusted Little Kernel and Trusty Secure OS.
- A Trusted Board Boot implementation, conforming to all mandatory TBBR requirements. This includes image authentication, Firmware Update (or recovery mode), and packaging of the various firmware images into a Firmware Image Package (FIP).
- Pre-integration of TBB with the ARM TrustZone CryptoCell product, to take advantage of its hardware Root of Trust and crypto acceleration services.
- Support for alternative boot flows, for example to support platforms where the EL3 Runtime Software is loaded using other firmware or a separate secure system processor.
- Support for the GCC, LLVM and ARM Compiler 6 toolchains.
For a full description of functionality and implementation details, please see the Firmware Design and supporting documentation. The Change Log provides details of changes made since the last release.
Platforms
Various AArch32 and AArch64 builds of this release has been tested on variants r0, r1 and r2 of the Juno ARM Development Platform.
Various AArch64 builds of this release have been tested on the following ARM FVPs (64-bit host machine only):
NOTE: Unless otherwise stated, the FVP Version is 11.0, Build 11.0.34.
- Foundation_Platform
- FVP_Base_AEMv8A-AEMv8A (Version 8.5, Build 0.8.8502)
- FVP_Base_Cortex-A35x4
- FVP_Base_Cortex-A53x4
- FVP_Base_Cortex-A57x4-A53x4
- FVP_Base_Cortex-A57x4
- FVP_Base_Cortex-A72x4-A53x4
- FVP_Base_Cortex-A72x4
- FVP_Base_Cortex-A73x4-A53x4
- FVP_Base_Cortex-A73x4
- FVP_CSS_SGM-775 (Version 11.0, Build 11.0.36)
Various AArch32 builds of this release has been tested on the following ARM FVPs (64-bit host machine only):
- FVP_Base_AEMv8A-AEMv8A (Version 8.5, Build 0.8.8502)
- FVP_Base_Cortex-A32x4
The Foundation FVP can be downloaded free of charge. The Base FVPs can be licensed from ARM. See the ARM FVP website.
All the above platforms have been tested with Linaro Release 17.04.
This release also contains the following platform support:
- HiKey and HiKey960 boards
- MediaTek MT6795 and MT8173 SoCs
- NVidia T132, T186 and T210 SoCs
- QEMU emulator
- RockChip RK3328, RK3368 and RK3399 SoCs
- Socionext UniPhier SoC family
- Xilinx Zynq UltraScale + MPSoC
Still to Come
- More platform support.
- Ongoing support for new architectural features, CPUs and System IP.
- Ongoing support for new PSCI, SCMI and TBBR features.
- Ongoing security hardening, optimization and quality improvements.
For a full list of detailed issues in the current code, please see the Change Log and the GitHub issue tracker.
Getting Started
Get the Trusted Firmware source code from GitHub.
See the User Guide for instructions on how to install, build and use the Trusted Firmware with the ARM FVPs.
See the Firmware Design for information on how the Trusted Firmware works.
See the Porting Guide as well for information about how to use this software on another ARMv8-A platform.
See the Contributing Guidelines for information on how to contribute to this project and the Acknowledgments file for a list of contributors to the project.
Feedback and support
ARM welcomes any feedback on Trusted Firmware. If you think you have found a security vulnerability, please report this using the process defined in the Trusted Firmware Security Centre. For all other feedback, please use the GitHub issue tracker.
ARM licensees may contact ARM directly via their partner managers.
Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.