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ARM Trusted Firmware User Guide

Contents :

  1. Introduction

  2. Host machine requirements

  3. Tools

  4. Getting the Trusted Firmware source code

  5. Building the Trusted Firmware

  6. Building a FIP for Juno and FVP

  7. EL3 payloads alternative boot flow

  8. Preloaded BL33 alternative boot flow

  9. Running the software on FVP

  10. Running the software on Juno

  11. Introduction

This document describes how to build ARM Trusted Firmware (TF) and run it with a tested set of other software components using defined configurations on the Juno ARM development platform and ARM Fixed Virtual Platform (FVP) models. It is possible to use other software components, configurations and platforms but that is outside the scope of this document.

This document assumes that the reader has previous experience running a fully bootable Linux software stack on Juno or FVP using the prebuilt binaries and filesystems provided by Linaro. Further information may be found in the Instructions for using the Linaro software deliverables. It also assumes that the user understands the role of the different software components required to boot a Linux system:

  • Specific firmware images required by the platform (e.g. SCP firmware on Juno)
  • Normal world bootloader (e.g. UEFI or U-Boot)
  • Device tree
  • Linux kernel image
  • Root filesystem

This document also assumes that the user is familiar with the FVP models and the different command line options available to launch the model.

This document should be used in conjunction with the Firmware Design.

  1. Host machine requirements

The minimum recommended machine specification for building the software and running the FVP models is a dual-core processor running at 2GHz with 12GB of RAM. For best performance, use a machine with a quad-core processor running at 2.6GHz with 16GB of RAM.

The software has been tested on Ubuntu 14.04 LTS (64-bit). Packages used for building the software were installed from that distribution unless otherwise specified.

The software has also been built on Windows 7 Enterprise SP1, using CMD.EXE, Cygwin, and Msys (MinGW) shells, using version 4.9.1 of the GNU toolchain.

  1. Tools

Install the required packages to build Trusted Firmware with the following command:

sudo apt-get install build-essential gcc make git

Download and install the AArch64 little-endian GCC cross compiler as indicated in the Linaro instructions.

In addition, the following optional packages and tools may be needed:

  • device-tree-compiler package if you need to rebuild the Flattened Device Tree (FDT) source files (.dts files) provided with this software.

  • libssl-dev package if Trusted Board Boot is enabled in the build.

  • For debugging, ARM Development Studio 5 (DS-5).

  1. Getting the Trusted Firmware source code

Download the Trusted Firmware source code from Github:

git clone https://github.com/ARM-software/arm-trusted-firmware.git
  1. Building the Trusted Firmware

  • Before building Trusted Firmware, the environment variable CROSS_COMPILE must point to the Linaro cross compiler:

    export CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-linux-gnu-

  • Change to the root directory of the Trusted Firmware source tree and build:

    make PLAT=<platform> all

    Notes:

    • If PLAT is not specified, fvp is assumed by default. See the "Summary of build options" for more information on available build options.

    • The TSP (Test Secure Payload), corresponding to the BL32 image, is not compiled in by default. Refer to the "Building the Test Secure Payload" section below.

    • By default this produces a release version of the build. To produce a debug version instead, refer to the "Debugging options" section below.

    • The build process creates products in a build directory tree, building the objects and binaries for each boot loader stage in separate sub-directories. The following boot loader binary files are created from the corresponding ELF files:

      • build/<platform>/<build-type>/bl1.bin
      • build/<platform>/<build-type>/bl2.bin
      • build/<platform>/<build-type>/bl31.bin

      where <platform> is the name of the chosen platform and <build-type> is either debug or release. The actual number of images might differ depending on the platform.

  • Build products for a specific build variant can be removed using:

    make DEBUG=<D> PLAT=<platform> clean

    ... where <D> is 0 or 1, as specified when building.

    The build tree can be removed completely using:

    make realclean

Summary of build options

ARM Trusted Firmware build system supports the following build options. Unless mentioned otherwise, these options are expected to be specified at the build command line and are not to be modified in any component makefiles. Note that the build system doesn't track dependency for build options. Therefore, if any of the build options are changed from a previous build, a clean build must be performed.

Common build options

  • SCP_BL2: Path to SCP_BL2 image in the host file system. This image is optional. If a SCP_BL2 image is present then this option must be passed for the fip target.

  • BL33: Path to BL33 image in the host file system. This is mandatory for fip target in case the BL2 from ARM Trusted Firmware is used.

  • BL2: This is an optional build option which specifies the path to BL2 image for the fip target. In this case, the BL2 in the ARM Trusted Firmware will not be built.

  • BL31: This is an optional build option which specifies the path to BL31 image for the fip target. In this case, the BL31 in the ARM Trusted Firmware will not be built.

  • BL32: This is an optional build option which specifies the path to BL32 image for the fip target. In this case, the BL32 in the ARM Trusted Firmware will not be built.

  • FIP_NAME: This is an optional build option which specifies the FIP filename for the fip target. Default is fip.bin.

  • FWU_FIP_NAME: This is an optional build option which specifies the FWU FIP filename for the fwu_fip target. Default is fwu_fip.bin.

  • BL2U: This is an optional build option which specifies the path to BL2U image. In this case, the BL2U in the ARM Trusted Firmware will not be built.

  • SCP_BL2U: Path to SCP_BL2U image in the host file system. This image is optional. It is only needed if the platform makefile specifies that it is required in order to build the fwu_fip target.

  • NS_BL2U: Path to NS_BL2U image in the host file system. This image is optional. It is only needed if the platform makefile specifies that it is required in order to build the fwu_fip target.

  • DEBUG: Chooses between a debug and release build. It can take either 0 (release) or 1 (debug) as values. 0 is the default.

  • LOG_LEVEL: Chooses the log level, which controls the amount of console log output compiled into the build. This should be one of the following:

    0  (LOG_LEVEL_NONE)
10 (LOG_LEVEL_NOTICE)
20 (LOG_LEVEL_ERROR)
30 (LOG_LEVEL_WARNING)
40 (LOG_LEVEL_INFO)
50 (LOG_LEVEL_VERBOSE)

    All log output up to and including the log level is compiled into the build. The default value is 40 in debug builds and 20 in release builds.

  • NS_TIMER_SWITCH: Enable save and restore for non-secure timer register contents upon world switch. It can take either 0 (don't save and restore) or 1 (do save and restore). 0 is the default. An SPD may set this to 1 if it wants the timer registers to be saved and restored.

  • PLAT: Choose a platform to build ARM Trusted Firmware for. The chosen platform name must be subdirectory of any depth under plat/, and must contain a platform makefile named platform.mk.

  • SPD: Choose a Secure Payload Dispatcher component to be built into the Trusted Firmware. The value should be the path to the directory containing the SPD source, relative to services/spd/; the directory is expected to contain a makefile called <spd-value>.mk.

  • V: Verbose build. If assigned anything other than 0, the build commands are printed. Default is 0.

  • ARM_GIC_ARCH: Choice of ARM GIC architecture version used by the ARM Legacy GIC driver for implementing the platform GIC API. This API is used by the interrupt management framework. Default is 2 (that is, version 2.0). This build option is deprecated.

  • ARM_CCI_PRODUCT_ID: Choice of ARM CCI product used by the platform. This is used to determine the number of valid slave interfaces available in the ARM CCI driver. Default is 400 (that is, CCI-400).

  • RESET_TO_BL31: Enable BL31 entrypoint as the CPU reset vector instead of the BL1 entrypoint. It can take the value 0 (CPU reset to BL1 entrypoint) or 1 (CPU reset to BL31 entrypoint). The default value is 0.

  • CRASH_REPORTING: A non-zero value enables a console dump of processor register state when an unexpected exception occurs during execution of BL31. This option defaults to the value of DEBUG - i.e. by default this is only enabled for a debug build of the firmware.

  • ASM_ASSERTION: This flag determines whether the assertion checks within assembly source files are enabled or not. This option defaults to the value of DEBUG - that is, by default this is only enabled for a debug build of the firmware.

  • TSP_INIT_ASYNC: Choose BL32 initialization method as asynchronous or synchronous, (see "Initializing a BL32 Image" section in Firmware Design). It can take the value 0 (BL32 is initialized using synchronous method) or 1 (BL32 is initialized using asynchronous method). Default is 0.

  • USE_COHERENT_MEM: This flag determines whether to include the coherent memory region in the BL memory map or not (see "Use of Coherent memory in Trusted Firmware" section in Firmware Design). It can take the value 1 (Coherent memory region is included) or 0 (Coherent memory region is excluded). Default is 1.

  • TSP_NS_INTR_ASYNC_PREEMPT: A non zero value enables the interrupt routing model which routes non-secure interrupts asynchronously from TSP to EL3 causing immediate preemption of TSP. The EL3 is responsible for saving and restoring the TSP context in this routing model. The default routing model (when the value is 0) is to route non-secure interrupts to TSP allowing it to save its context and hand over synchronously to EL3 via an SMC.

  • TRUSTED_BOARD_BOOT: Boolean flag to include support for the Trusted Board Boot feature. When set to '1', BL1 and BL2 images include support to load and verify the certificates and images in a FIP, and BL1 includes support for the Firmware Update. The default value is '0'. Generation and inclusion of certificates in the FIP and FWU_FIP depends upon the value of the GENERATE_COT option.

  • GENERATE_COT: Boolean flag used to build and execute the cert_create tool to create certificates as per the Chain of Trust described in Trusted Board Boot. The build system then calls the fip_create tool to include the certificates in the FIP and FWU_FIP. Default value is '0'.

    Specify both TRUSTED_BOARD_BOOT=1 and GENERATE_COT=1 to include support for the Trusted Board Boot feature in the BL1 and BL2 images, to generate the corresponding certificates, and to include those certificates in the FIP and FWU_FIP.

    Note that if TRUSTED_BOARD_BOOT=0 and GENERATE_COT=1, the BL1 and BL2 images will not include support for Trusted Board Boot. The FIP will still include the corresponding certificates. This FIP can be used to verify the Chain of Trust on the host machine through other mechanisms.

    Note that if TRUSTED_BOARD_BOOT=1 and GENERATE_COT=0, the BL1 and BL2 images will include support for Trusted Board Boot, but the FIP and FWU_FIP will not include the corresponding certificates, causing a boot failure.

  • CREATE_KEYS: This option is used when GENERATE_COT=1. It tells the certificate generation tool to create new keys in case no valid keys are present or specified. Allowed options are '0' or '1'. Default is '1'.

  • SAVE_KEYS: This option is used when GENERATE_COT=1. It tells the certificate generation tool to save the keys used to establish the Chain of Trust. Allowed options are '0' or '1'. Default is '0' (do not save).

    Note: This option depends on 'CREATE_KEYS' to be enabled. If the keys already exist in disk, they will be overwritten without further notice.

  • ROT_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the ROT private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • TRUSTED_WORLD_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the Trusted World private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • NON_TRUSTED_WORLD_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the Non-Trusted World private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • SCP_BL2_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the SCP_BL2 private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • BL31_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the BL31 private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • BL32_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the BL32 private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • BL33_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the BL33 private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • PROGRAMMABLE_RESET_ADDRESS: This option indicates whether the reset vector address can be programmed or is fixed on the platform. It can take either 0 (fixed) or 1 (programmable). Default is 0. If the platform has a programmable reset address, it is expected that a CPU will start executing code directly at the right address, both on a cold and warm reset. In this case, there is no need to identify the entrypoint on boot and the boot path can be optimised. The plat_get_my_entrypoint() platform porting interface does not need to be implemented in this case.

  • COLD_BOOT_SINGLE_CPU: This option indicates whether the platform may release several CPUs out of reset. It can take either 0 (several CPUs may be brought up) or 1 (only one CPU will ever be brought up during cold reset). Default is 0. If the platform always brings up a single CPU, there is no need to distinguish between primary and secondary CPUs and the boot path can be optimised. The plat_is_my_cpu_primary() and plat_secondary_cold_boot_setup() platform porting interfaces do not need to be implemented in this case.

  • PSCI_EXTENDED_STATE_ID: As per PSCI1.0 Specification, there are 2 formats possible for the PSCI power-state parameter viz original and extended State-ID formats. This flag if set to 1, configures the generic PSCI layer to use the extended format. The default value of this flag is 0, which means by default the original power-state format is used by the PSCI implementation. This flag should be specified by the platform makefile and it governs the return value of PSCI_FEATURES API for CPU_SUSPEND smc function id.

  • ERROR_DEPRECATED: This option decides whether to treat the usage of deprecated platform APIs, helper functions or drivers within Trusted Firmware as error. It can take the value 1 (flag the use of deprecated APIs as error) or 0. The default is 0.

  • SPIN_ON_BL1_EXIT: This option introduces an infinite loop in BL1. It can take either 0 (no loop) or 1 (add a loop). 0 is the default. This loop stops execution in BL1 just before handing over to BL31. At this point, all firmware images have been loaded in memory, and the MMU and caches are turned off. Refer to the "Debugging options" section for more details.

  • EL3_PAYLOAD_BASE: This option enables booting an EL3 payload instead of the normal boot flow. It must specify the entry point address of the EL3 payload. Please refer to the "Booting an EL3 payload" section for more details.

  • PRELOADED_BL33_BASE: This option enables booting a preloaded BL33 image instead of the normal boot flow. When defined, it must specify the entry point address for the preloaded BL33 image. This option is incompatible with EL3_PAYLOAD_BASE. If both are defined, EL3_PAYLOAD_BASE has priority over PRELOADED_BL33_BASE.

  • PL011_GENERIC_UART: Boolean option to indicate the PL011 driver that the underlying hardware is not a full PL011 UART but a minimally compliant generic UART, which is a subset of the PL011. The driver will not access any register that is not part of the SBSA generic UART specification. Default value is 0 (a full PL011 compliant UART is present).

  • CTX_INCLUDE_AARCH32_REGS : Boolean option that, when set to 1, will cause the AArch32 system registers to be included when saving and restoring the CPU context. The option must be set to 0 for AArch64-only platforms (that is on hardware that does not implement AArch32, or at least not at EL1 and higher ELs). Default value is 1.

  • CTX_INCLUDE_FPREGS: Boolean option that, when set to 1, will cause the FP registers to be included when saving and restoring the CPU context. Default is 0.

  • DISABLE_PEDANTIC: When set to 1 it will disable the -pedantic option in the GCC command line. Default is 0.

  • BUILD_STRING: Input string for VERSION_STRING, which allows the TF build to be uniquely identified. Defaults to the current git commit id.

  • VERSION_STRING: String used in the log output for each TF image. Defaults to a string formed by concatenating the version number, build type and build string.

  • BUILD_MESSAGE_TIMESTAMP: String used to identify the time and date of the compilation of each build. It must be set to a C string (including quotes where applicable). Defaults to a string that contains the time and date of the compilation.

  • HANDLE_EA_EL3_FIRST: When defined External Aborts and SError Interrupts will be always trapped in EL3 i.e. in BL31 at runtime.

  • ENABLE_PMF: Boolean option to enable support for optional Performance Measurement Framework(PMF). Default is 0.

  • ENABLE_PSCI_STAT: Boolean option to enable support for optional PSCI functions PSCI_STAT_RESIDENCY and PSCI_STAT_COUNT. Default is 0. Enabling this option enables the ENABLE_PMF build option as well. The PMF is used for collecting the statistics.

ARM development platform specific build options

  • ARM_TSP_RAM_LOCATION: location of the TSP binary. Options:
    • tsram : Trusted SRAM (default option)
    • tdram : Trusted DRAM (if available)
    • dram : Secure region in DRAM (configured by the TrustZone controller)

For a better understanding of these options, the ARM development platform memory map is explained in the Firmware Design.

  • ARM_ROTPK_LOCATION: used when TRUSTED_BOARD_BOOT=1. It specifies the location of the ROTPK hash returned by the function plat_get_rotpk_info() for ARM platforms. Depending on the selected option, the proper private key must be specified using the ROT_KEY option when building the Trusted Firmware. This private key will be used by the certificate generation tool to sign the BL2 and Trusted Key certificates. Available options for ARM_ROTPK_LOCATION are:

    • regs : return the ROTPK hash stored in the Trusted root-key storage registers. The private key corresponding to this ROTPK hash is not currently available.
    • devel_rsa : return a development public key hash embedded in the BL1 and BL2 binaries. This hash has been obtained from the RSA public key arm_rotpk_rsa.der, located in plat/arm/board/common/rotpk. To use this option, arm_rotprivk_rsa.pem must be specified as ROT_KEY when creating the certificates.

  • ARM_RECOM_STATE_ID_ENC: The PSCI1.0 specification recommends an encoding for the construction of composite state-ID in the power-state parameter. The existing PSCI clients currently do not support this encoding of State-ID yet. Hence this flag is used to configure whether to use the recommended State-ID encoding or not. The default value of this flag is 0, in which case the platform is configured to expect NULL in the State-ID field of power-state parameter.

  • ARM_DISABLE_TRUSTED_WDOG: boolean option to disable the Trusted Watchdog. By default, ARM platforms use a watchdog to trigger a system reset in case an error is encountered during the boot process (for example, when an image could not be loaded or authenticated). The watchdog is enabled in the early platform setup hook at BL1 and disabled in the BL1 prepare exit hook. The Trusted Watchdog may be disabled at build time for testing or development purposes.

  • ARM_CONFIG_CNTACR: boolean option to unlock access to the CNTBase frame registers by setting the CNTCTLBase.CNTACR register bits. The frame number is defined by 'PLAT_ARM_NSTIMER_FRAME_ID', which should match the frame used by the Non-Secure image (normally the Linux kernel). Default is true (access to the frame is allowed).

  • ARM_BOARD_OPTIMISE_MMAP: Boolean option to enable or disable optimisation of page table and MMU related macros PLAT_ARM_MMAP_ENTRIES and MAX_XLAT_TABLES. By default this flag is 0, which means it uses the default unoptimised values for these macros. ARM development platforms that wish to optimise memory usage for page tables need to set this flag to 1 and must override the related macros.

  • 'ARM_BL31_IN_DRAM': Boolean option to select loading of BL31 in TZC secured DRAM. By default, BL31 is in the secure SRAM. Set this flag to 1 to load BL31 in TZC secured DRAM. If TSP is present, then setting this option also sets the TSP location to DRAM and ignores the ARM_TSP_RAM_LOCATION build flag.

ARM CSS platform specific build options

  • CSS_DETECT_PRE_1_7_0_SCP: Boolean flag to detect SCP version incompatibility. Version 1.7.0 of the SCP firmware made a non-backwards compatible change to the MTL protocol, used for AP/SCP communication. Trusted Firmware no longer supports earlier SCP versions. If this option is set to 1 then Trusted Firmware will detect if an earlier version is in use. Default is 1.

  • CSS_LOAD_SCP_IMAGES: Boolean flag, which when set, adds SCP_BL2 and SCP_BL2U to the FIP and FWU_FIP respectively, and enables them to be loaded during boot. Default is 1.

ARM FVP platform specific build options

  • FVP_USE_GIC_DRIVER : Selects the GIC driver to be built. Options:

    • FVP_GICV2 : The GICv2 only driver is selected
    • FVP_GICV3 : The GICv3 only driver is selected (default option)
    • FVP_GICV3_LEGACY: The Legacy GICv3 driver is selected (deprecated) Note: If Trusted Firmware is compiled with this option on FVPs with GICv3 hardware, then it configures the hardware to run in GICv2 emulation mode

  • FVP_CLUSTER_COUNT : Configures the cluster count to be used to build the topology tree within Trusted Firmware. By default the Trusted Firmware is configured for dual cluster topology and this option can be used to override the default value.

  • FVP_USE_SP804_TIMER : Use the SP804 timer instead of the Generic Timer for functions that wait for an arbitrary time length (udelay and mdelay). The default value is 0.

  • FVP_INTERCONNECT_DRIVER: Selects the interconnect driver to be built. The default interconnect driver depends on the value of FVP_CLUSTER_COUNT as explained in the options below:

    • FVP_CCI : The CCI driver is selected. This is the default if 0 < FVP_CLUSTER_COUNT <= 2.
    • FVP_CCN : The CCN driver is selected. This is the default if FVP_CLUSTER_COUNT > 2.

Debugging options

To compile a debug version and make the build more verbose use

make PLAT=<platform> DEBUG=1 V=1 all

AArch64 GCC uses DWARF version 4 debugging symbols by default. Some tools (for example DS-5) might not support this and may need an older version of DWARF symbols to be emitted by GCC. This can be achieved by using the -gdwarf-<version> flag, with the version being set to 2 or 3. Setting the version to 2 is recommended for DS-5 versions older than 5.16.

When debugging logic problems it might also be useful to disable all compiler optimizations by using -O0.

NOTE: Using -O0 could cause output images to be larger and base addresses might need to be recalculated (see the Memory layout on ARM development platforms section in the Firmware Design).

Extra debug options can be passed to the build system by setting CFLAGS:

CFLAGS='-O0 -gdwarf-2'                                     \
make PLAT=<platform> DEBUG=1 V=1 all

It is also possible to introduce an infinite loop to help in debugging the post-BL2 phase of the Trusted Firmware. This can be done by rebuilding BL1 with the SPIN_ON_BL1_EXIT=1 build flag. Refer to the "Summary of build options" section. In this case, the developer may take control of the target using a debugger when indicated by the console output. When using DS-5, the following commands can be used:

# Stop target execution
interrupt

#
# Prepare your debugging environment, e.g. set breakpoints
#

# Jump over the debug loop
set var $AARCH64::$Core::$PC = $AARCH64::$Core::$PC + 4

# Resume execution
continue

Building the Test Secure Payload

The TSP is coupled with a companion runtime service in the BL31 firmware, called the TSPD. Therefore, if you intend to use the TSP, the BL31 image must be recompiled as well. For more information on SPs and SPDs, see the "Secure-EL1 Payloads and Dispatchers" section in the Firmware Design.

First clean the Trusted Firmware build directory to get rid of any previous BL31 binary. Then to build the TSP image use:

make PLAT=<platform> SPD=tspd all

An additional boot loader binary file is created in the build directory:

`build/<platform>/<build-type>/bl32.bin`

Checking source code style

When making changes to the source for submission to the project, the source must be in compliance with the Linux style guide, and to assist with this check the project Makefile contains two targets, which both utilise the checkpatch.pl script that ships with the Linux source tree.

To check the entire source tree, you must first download a copy of checkpatch.pl (or the full Linux source), set the CHECKPATCH environment variable to point to the script and build the target checkcodebase:

make CHECKPATCH=<path-to-linux>/linux/scripts/checkpatch.pl checkcodebase

To just check the style on the files that differ between your local branch and the remote master, use:

make CHECKPATCH=<path-to-linux>/linux/scripts/checkpatch.pl checkpatch

If you wish to check your patch against something other than the remote master, set the BASE_COMMIT variable to your desired branch. By default, BASE_COMMIT is set to origin/master.

Building and using the FIP tool

Firmware Image Package (FIP) is a packaging format used by the Trusted Firmware project to package firmware images in a single binary. The number and type of images that should be packed in a FIP is platform specific and may include TF images and other firmware images required by the platform. For example, most platforms require a BL33 image which corresponds to the normal world bootloader (e.g. UEFI or U-Boot).

The TF build system provides the make target fip to create a FIP file for the specified platform using the FIP creation tool included in the TF project. For example, to build a FIP file for FVP, packaging TF images and a BL33 image:

make PLAT=fvp BL33=<path/to/bl33.bin> fip

The resulting FIP may be found in:

`build/fvp/<build-type>/fip.bin`

For advanced operations on FIP files, it is also possible to independently build the tool and create or modify FIPs using this tool. To do this, follow these steps:

It is recommended to remove old artifacts before building the tool:

make -C tools/fip_create clean

Build the tool:

make [DEBUG=1] [V=1] fiptool

The tool binary can be located in:

./tools/fip_create/fip_create

Invoking the tool with --help will print a help message with all available options.

Example 1: create a new Firmware package fip.bin that contains BL2 and BL31:

./tools/fip_create/fip_create \
    --tb-fw build/<platform>/<build-type>/bl2.bin \
    --soc-fw build/<platform>/<build-type>/bl31.bin \
    fip.bin

Example 2: view the contents of an existing Firmware package:

./tools/fip_create/fip_create --dump <path-to>/fip.bin

Example 3: update the entries of an existing Firmware package:

# Change the BL2 from Debug to Release version
./tools/fip_create/fip_create \
    --tb-fw build/<platform>/release/bl2.bin \
    build/<platform>/debug/fip.bin

Example 4: unpack all entries from an existing Firmware package:

# Images will be unpacked to the working directory
./tools/fip_create/fip_create --unpack <path-to>/fip.bin

More information about FIP can be found in the [Firmware Design document] Firmware Design.

Building FIP images with support for Trusted Board Boot

Trusted Board Boot primarily consists of the following two features:

The following steps should be followed to build FIP and (optionally) FWU_FIP images with support for these features:

  1. Fulfill the dependencies of the mbedtls cryptographic and image parser modules by checking out a recent version of the mbed TLS Repository. It is important to use a version that is compatible with TF and fixes any known security vulnerabilities. See mbed TLS Security Center for more information. This version of TF is tested with tag mbedtls-2.2.0.

    The drivers/auth/mbedtls/mbedtls_*.mk files contain the list of mbed TLS source files the modules depend upon. include/drivers/auth/mbedtls/mbedtls_config.h contains the configuration options required to build the mbed TLS sources.

    Note that the mbed TLS library is licensed under the Apache version 2.0 license. Using mbed TLS source code will affect the licensing of Trusted Firmware binaries that are built using this library.

  2. To build the FIP image, ensure the following command line variables are set while invoking make to build Trusted Firmware:

    • MBEDTLS_DIR=<path of the directory containing mbed TLS sources>
    • TRUSTED_BOARD_BOOT=1
    • GENERATE_COT=1

    In the case of ARM platforms, the location of the ROTPK hash must also be specified at build time. Two locations are currently supported (see ARM_ROTPK_LOCATION build option):

    • ARM_ROTPK_LOCATION=regs: the ROTPK hash is obtained from the Trusted root-key storage registers present in the platform. On Juno, this registers are read-only. On FVP Base and Cortex models, the registers are read-only, but the value can be specified using the command line option bp.trusted_key_storage.public_key when launching the model. On both Juno and FVP models, the default value corresponds to an ECDSA-SECP256R1 public key hash, whose private part is not currently available.

    • ARM_ROTPK_LOCATION=devel_rsa: use the ROTPK hash that is hardcoded in the ARM platform port. The private/public RSA key pair may be found in plat/arm/board/common/rotpk.

    Example of command line using RSA development keys:

    MBEDTLS_DIR=<path of the directory containing mbed TLS sources> \
make PLAT=<platform> TRUSTED_BOARD_BOOT=1 GENERATE_COT=1        \
ARM_ROTPK_LOCATION=devel_rsa                                    \
ROT_KEY=plat/arm/board/common/rotpk/arm_rotprivk_rsa.pem        \
BL33=<path-to>/<bl33_image>                                     \
all fip

    The result of this build will be the bl1.bin and the fip.bin binaries. This FIP will include the certificates corresponding to the Chain of Trust described in the TBBR-client document. These certificates can also be found in the output build directory.

  3. The optional FWU_FIP contains any additional images to be loaded from Non-Volatile storage during the Firmware Update process. To build the FWU_FIP, any FWU images required by the platform must be specified on the command line. On ARM development platforms like Juno, these are:

    • NS_BL2U. The AP non-secure Firmware Updater image.
    • SCP_BL2U. The SCP Firmware Update Configuration image.

    Example of Juno command line for generating both fwu and fwu_fip targets using RSA development:

    MBEDTLS_DIR=<path of the directory containing mbed TLS sources> \
make PLAT=juno TRUSTED_BOARD_BOOT=1 GENERATE_COT=1              \
ARM_ROTPK_LOCATION=devel_rsa                                    \
ROT_KEY=plat/arm/board/common/rotpk/arm_rotprivk_rsa.pem        \
BL33=<path-to>/<bl33_image>                                     \
SCP_BL2=<path-to>/<scp_bl2_image>                               \
SCP_BL2U=<path-to>/<scp_bl2u_image>                             \
NS_BL2U=<path-to>/<ns_bl2u_image>                               \
all fip fwu_fip

    Note: The BL2U image will be built by default and added to the FWU_FIP. The user may override this by adding BL2U=<path-to>/<bl2u_image> to the command line above.

    Note: Building and installing the non-secure and SCP FWU images (NS_BL1U, NS_BL2U and SCP_BL2U) is outside the scope of this document.

    The result of this build will be bl1.bin, fip.bin and fwu_fip.bin binaries. Both the FIP and FWU_FIP will include the certificates corresponding to the Chain of Trust described in the TBBR-client document. These certificates can also be found in the output build directory.

Building the Certificate Generation Tool

The cert_create tool is built as part of the TF build process when the fip make target is specified and TBB is enabled (as described in the previous section), but it can also be built separately with the following command:

make PLAT=<platform> [DEBUG=1] [V=1] certtool

Specifying the platform is mandatory since the tool is platform specific. DEBUG=1 builds the tool in debug mode. V=1 makes the build process more verbose. The following command should be used to obtain help about the tool:

./tools/cert_create/cert_create -h
  1. Building a FIP for Juno and FVP

This section provides Juno and FVP specific instructions to build Trusted Firmware, obtain the additional required firmware, and pack it all together in a single FIP binary. It assumes that a Linaro Release has been installed.

Note: follow the full instructions for one platform before switching to a different one. Mixing instructions for different platforms may result in corrupted binaries.

  1. Clean the working directory

    make realclean

  2. Obtain SCP_BL2 (Juno) and BL33 (all platforms)

    Use the fip_create tool to extract the SCP_BL2 and BL33 images from the FIP package included in the Linaro release:

    # Build the fip_create tool
make [DEBUG=1] [V=1] fiptool

# Unpack firmware images from Linaro FIP
./tools/fip_create/fip_create --unpack \
     <path/to/linaro/release>/fip.bin

    The unpack operation will result in a set of binary images extracted to the working directory. The SCP_BL2 image corresponds to scp-fw.bin and BL33 corresponds to nt-fw.bin.

    Note: the fip_create tool will complain if the images to be unpacked already exist in the current directory. If that is the case, either delete those files or use the --force option to overwrite.

  3. Build TF images and create a new FIP

    # Juno
make PLAT=juno SCP_BL2=scp-fw.bin BL33=nt-fw.bin all fip

# FVP
make PLAT=fvp BL33=nt-fw.bin all fip

The resulting BL1 and FIP images may be found in:

# Juno
./build/juno/release/bl1.bin
./build/juno/release/fip.bin

# FVP
./build/fvp/release/bl1.bin
./build/fvp/release/fip.bin
  1. EL3 payloads alternative boot flow

On a pre-production system, the ability to execute arbitrary, bare-metal code at the highest exception level is required. It allows full, direct access to the hardware, for example to run silicon soak tests.

Although it is possible to implement some baremetal secure firmware from scratch, this is a complex task on some platforms, depending on the level of configuration required to put the system in the expected state.

Rather than booting a baremetal application, a possible compromise is to boot EL3 payloads through the Trusted Firmware instead. This is implemented as an alternative boot flow, where a modified BL2 boots an EL3 payload, instead of loading the other BL images and passing control to BL31. It reduces the complexity of developing EL3 baremetal code by:

  • putting the system into a known architectural state;
  • taking care of platform secure world initialization;
  • loading the SCP_BL2 image if required by the platform.

When booting an EL3 payload on ARM standard platforms, the configuration of the TrustZone controller is simplified such that only region 0 is enabled and is configured to permit secure access only. This gives full access to the whole DRAM to the EL3 payload.

The system is left in the same state as when entering BL31 in the default boot flow. In particular:

  • Running in EL3;
  • Current state is AArch64;
  • Little-endian data access;
  • All exceptions disabled;
  • MMU disabled;
  • Caches disabled.

Booting an EL3 payload

The EL3 payload image is a standalone image and is not part of the FIP. It is not loaded by the Trusted Firmware. Therefore, there are 2 possible scenarios:

  • The EL3 payload may reside in non-volatile memory (NVM) and execute in place. In this case, booting it is just a matter of specifying the right address in NVM through EL3_PAYLOAD_BASE when building the TF.

  • The EL3 payload needs to be loaded in volatile memory (e.g. DRAM) at run-time.

To help in the latter scenario, the SPIN_ON_BL1_EXIT=1 build option can be used. The infinite loop that it introduces in BL1 stops execution at the right moment for a debugger to take control of the target and load the payload (for example, over JTAG).

It is expected that this loading method will work in most cases, as a debugger connection is usually available in a pre-production system. The user is free to use any other platform-specific mechanism to load the EL3 payload, though.

Booting an EL3 payload on FVP

The EL3 payloads boot flow requires the CPU's mailbox to be cleared at reset for the secondary CPUs holding pen to work properly. Unfortunately, its reset value is undefined on the FVP platform and the FVP platform code doesn't clear it. Therefore, one must modify the way the model is normally invoked in order to clear the mailbox at start-up.

One way to do that is to create an 8-byte file containing all zero bytes using the following command:

dd if=/dev/zero of=mailbox.dat bs=1 count=8

and pre-load it into the FVP memory at the mailbox address (i.e. 0x04000000) using the following model parameters:

--data cluster0.cpu0=mailbox.dat@0x04000000   [Base FVPs]
--data=mailbox.dat@0x04000000                 [Foundation FVP]

To provide the model with the EL3 payload image, the following methods may be used:

  1. If the EL3 payload is able to execute in place, it may be programmed into flash memory. On Base Cortex and AEM FVPs, the following model parameter loads it at the base address of the NOR FLASH1 (the NOR FLASH0 is already used for the FIP):

    -C bp.flashloader1.fname="/path/to/el3-payload"

    On Foundation FVP, there is no flash loader component and the EL3 payload may be programmed anywhere in flash using method 3 below.

  2. When using the SPIN_ON_BL1_EXIT=1 loading method, the following DS-5 command may be used to load the EL3 payload ELF image over JTAG:

    load /path/to/el3-payload.elf

  3. The EL3 payload may be pre-loaded in volatile memory using the following model parameters:

    --data cluster0.cpu0="/path/to/el3-payload"@address  [Base FVPs]
--data="/path/to/el3-payload"@address                [Foundation FVP]

    The address provided to the FVP must match the EL3_PAYLOAD_BASE address used when building the Trusted Firmware.

Booting an EL3 payload on Juno

If the EL3 payload is able to execute in place, it may be programmed in flash memory by adding an entry in the SITE1/HBI0262x/images.txt configuration file on the Juno SD card (where x depends on the revision of the Juno board). Refer to the Juno Getting Started Guide, section 2.3 "Flash memory programming" for more information.

Alternatively, the same DS-5 command mentioned in the FVP section above can be used to load the EL3 payload's ELF file over JTAG on Juno.

  1. Preloaded BL33 alternative boot flow

Some platforms have the ability to preload BL33 into memory instead of relying on Trusted Firmware to load it. This may simplify packaging of the normal world code and improve performance in a development environment. When secure world cold boot is complete, Trusted Firmware simply jumps to a BL33 base address provided at build time.

For this option to be used, the PRELOADED_BL33_BASE build option has to be used when compiling the Trusted Firmware. For example, the following command will create a FIP without a BL33 and prepare to jump to a BL33 image loaded at address 0x80000000:

make PRELOADED_BL33_BASE=0x80000000 PLAT=fvp all fip

Boot of a preloaded bootwrapped kernel image on Base FVP

The following example uses the AArch64 boot wrapper. This simplifies normal world booting while also making use of TF features. It can be obtained from its repository with:

git clone git://git.kernel.org/pub/scm/linux/kernel/git/mark/boot-wrapper-aarch64.git

After compiling it, an ELF file is generated. It can be loaded with the following command:

<path-to>/FVP_Base_AEMv8A-AEMv8A              \
    -C bp.secureflashloader.fname=bl1.bin     \
    -C bp.flashloader0.fname=fip.bin          \
    -a cluster0.cpu0=<bootwrapped-kernel.elf> \
    --start cluster0.cpu0=0x0

The -a cluster0.cpu0=<bootwrapped-kernel.elf> option loads the ELF file. It also sets the PC register to the ELF entry point address, which is not the desired behaviour, so the --start cluster0.cpu0=0x0 option forces the PC back to 0x0 (the BL1 entry point address) on CPU #0. The PRELOADED_BL33_BASE define used when compiling the FIP must match the ELF entry point.

Boot of a preloaded bootwrapped kernel image on Juno

The procedure to obtain and compile the boot wrapper is very similar to the case of the FVP. Once compiled, the SPIN_ON_BL1_EXIT=1 loading method explained above in the EL3 payload boot flow section may be used to load the ELF file over JTAG on Juno.

  1. Running the software on FVP

This version of the ARM Trusted Firmware has been tested on the following ARM FVPs (64-bit versions only).

  • Foundation_Platform (Version 9.5, Build 9.5.40)
  • FVP_Base_AEMv8A-AEMv8A (Version 7.2, Build 0.8.7202)
  • FVP_Base_Cortex-A57x4-A53x4 (Version 7.2, Build 0.8.7202)
  • FVP_Base_Cortex-A57x1-A53x1 (Version 7.2, Build 0.8.7202)
  • FVP_Base_Cortex-A57x2-A53x4 (Version 7.2, Build 0.8.7202)

NOTE: The build numbers quoted above are those reported by launching the FVP with the --version parameter. Foundation_Platform tarball for --version 9.5.40 is labeled as version 9.5.41.

NOTE: The software will not work on Version 1.0 of the Foundation FVP. The commands below would report an unhandled argument error in this case.

NOTE: The Foundation FVP does not provide a debugger interface.

The Foundation FVP is a cut down version of the AArch64 Base FVP. It can be downloaded for free from ARM's website.

Please refer to the FVP documentation for a detailed description of the model parameter options. A brief description of the important ones that affect the ARM Trusted Firmware and normal world software behavior is provided below.

Obtaining the Flattened Device Trees

Depending on the FVP configuration and Linux configuration used, different FDT files are required. FDTs for the Foundation and Base FVPs can be found in the Trusted Firmware source directory under fdts/. The Foundation FVP has a subset of the Base FVP components. For example, the Foundation FVP lacks CLCD and MMC support, and has only one CPU cluster.

Note: It is not recommended to use the FDTs built along the kernel because not all FDTs are available from there.

  • fvp-base-gicv2-psci.dtb

    For use with both AEMv8 and Cortex-A57-A53 Base FVPs with Base memory map configuration.

  • fvp-base-gicv3-psci.dtb

    (Default) For use with both AEMv8 and Cortex-A57-A53 Base FVPs with Base memory map configuration and Linux GICv3 support.

  • fvp-foundation-gicv2-psci.dtb

    For use with Foundation FVP with Base memory map configuration.

  • fvp-foundation-gicv3-psci.dtb

    (Default) For use with Foundation FVP with Base memory map configuration and Linux GICv3 support.

Running on the Foundation FVP with reset to BL1 entrypoint

The following Foundation_Platform parameters should be used to boot Linux with 4 CPUs using the ARM Trusted Firmware.

<path-to>/Foundation_Platform                   \
--cores=4                                       \
--secure-memory                                 \
--visualization                                 \
--gicv3                                         \
--data="<path-to>/<bl1-binary>"@0x0             \
--data="<path-to>/<FIP-binary>"@0x08000000      \
--data="<path-to>/<fdt>"@0x83000000             \
--data="<path-to>/<kernel-binary>"@0x80080000   \
--block-device="<path-to>/<file-system-image>"

Notes:

  • BL1 is loaded at the start of the Trusted ROM.
  • The Firmware Image Package is loaded at the start of NOR FLASH0.
  • The Linux kernel image and device tree are loaded in DRAM.
  • The default use-case for the Foundation FVP is to use the --gicv3 option and enable the GICv3 device in the model. Note that without this option, the Foundation FVP defaults to legacy (Versatile Express) memory map which is not supported by ARM Trusted Firmware.

Running on the AEMv8 Base FVP with reset to BL1 entrypoint

The following FVP_Base_AEMv8A-AEMv8A parameters should be used to boot Linux with 8 CPUs using the ARM Trusted Firmware.

<path-to>/FVP_Base_AEMv8A-AEMv8A                            \
-C pctl.startup=0.0.0.0                                     \
-C bp.secure_memory=1                                       \
-C bp.tzc_400.diagnostics=1                                 \
-C cluster0.NUM_CORES=4                                     \
-C cluster1.NUM_CORES=4                                     \
-C cache_state_modelled=1                                   \
-C bp.secureflashloader.fname="<path-to>/<bl1-binary>"      \
-C bp.flashloader0.fname="<path-to>/<FIP-binary>"           \
--data cluster0.cpu0="<path-to>/<fdt>"@0x83000000           \
--data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000 \
-C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"

Running on the Cortex-A57-A53 Base FVP with reset to BL1 entrypoint

The following FVP_Base_Cortex-A57x4-A53x4 model parameters should be used to boot Linux with 8 CPUs using the ARM Trusted Firmware.

<path-to>/FVP_Base_Cortex-A57x4-A53x4                       \
-C pctl.startup=0.0.0.0                                     \
-C bp.secure_memory=1                                       \
-C bp.tzc_400.diagnostics=1                                 \
-C cache_state_modelled=1                                   \
-C bp.secureflashloader.fname="<path-to>/<bl1-binary>"      \
-C bp.flashloader0.fname="<path-to>/<FIP-binary>"           \
--data cluster0.cpu0="<path-to>/<fdt>"@0x83000000           \
--data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000 \
-C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"

Running on the AEMv8 Base FVP with reset to BL31 entrypoint

The following FVP_Base_AEMv8A-AEMv8A parameters should be used to boot Linux with 8 CPUs using the ARM Trusted Firmware.

<path-to>/FVP_Base_AEMv8A-AEMv8A                             \
-C pctl.startup=0.0.0.0                                      \
-C bp.secure_memory=1                                        \
-C bp.tzc_400.diagnostics=1                                  \
-C cluster0.NUM_CORES=4                                      \
-C cluster1.NUM_CORES=4                                      \
-C cache_state_modelled=1                                    \
-C cluster0.cpu0.RVBAR=0x04023000                            \
-C cluster0.cpu1.RVBAR=0x04023000                            \
-C cluster0.cpu2.RVBAR=0x04023000                            \
-C cluster0.cpu3.RVBAR=0x04023000                            \
-C cluster1.cpu0.RVBAR=0x04023000                            \
-C cluster1.cpu1.RVBAR=0x04023000                            \
-C cluster1.cpu2.RVBAR=0x04023000                            \
-C cluster1.cpu3.RVBAR=0x04023000                            \
--data cluster0.cpu0="<path-to>/<bl31-binary>"@0x04023000    \
--data cluster0.cpu0="<path-to>/<bl32-binary>"@0x04001000    \
--data cluster0.cpu0="<path-to>/<bl33-binary>"@0x88000000    \
--data cluster0.cpu0="<path-to>/<fdt>"@0x83000000            \
--data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000  \
-C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"

Notes:

  • Since a FIP is not loaded when using BL31 as reset entrypoint, the --data="<path-to><bl31|bl32|bl33-binary>"@<base-address-of-binary> parameter is needed to load the individual bootloader images in memory. BL32 image is only needed if BL31 has been built to expect a Secure-EL1 Payload.

  • The -C cluster<X>.cpu<Y>.RVBAR=@<base-address-of-bl31> parameter, where X and Y are the cluster and CPU numbers respectively, is used to set the reset vector for each core.

  • Changing the default value of ARM_TSP_RAM_LOCATION will also require changing the value of --data="<path-to><bl32-binary>"@<base-address-of-bl32> to the new value of BL32_BASE.

Running on the Cortex-A57-A53 Base FVP with reset to BL31 entrypoint

The following FVP_Base_Cortex-A57x4-A53x4 model parameters should be used to boot Linux with 8 CPUs using the ARM Trusted Firmware.

<path-to>/FVP_Base_Cortex-A57x4-A53x4                        \
-C pctl.startup=0.0.0.0                                      \
-C bp.secure_memory=1                                        \
-C bp.tzc_400.diagnostics=1                                  \
-C cache_state_modelled=1                                    \
-C cluster0.cpu0.RVBARADDR=0x04023000                        \
-C cluster0.cpu1.RVBARADDR=0x04023000                        \
-C cluster0.cpu2.RVBARADDR=0x04023000                        \
-C cluster0.cpu3.RVBARADDR=0x04023000                        \
-C cluster1.cpu0.RVBARADDR=0x04023000                        \
-C cluster1.cpu1.RVBARADDR=0x04023000                        \
-C cluster1.cpu2.RVBARADDR=0x04023000                        \
-C cluster1.cpu3.RVBARADDR=0x04023000                        \
--data cluster0.cpu0="<path-to>/<bl31-binary>"@0x04023000    \
--data cluster0.cpu0="<path-to>/<bl32-binary>"@0x04001000    \
--data cluster0.cpu0="<path-to>/<bl33-binary>"@0x88000000    \
--data cluster0.cpu0="<path-to>/<fdt>"@0x83000000            \
--data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000  \
-C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"
  1. Running the software on Juno

This version of the ARM Trusted Firmware has been tested on Juno r0 and Juno r1.

To execute the software stack on Juno, the version of the Juno board recovery image indicated in the Linaro Release Notes must be installed. If you have an earlier version installed or are unsure which version is installed, please re-install the recovery image by following the Instructions for using Linaro's deliverables on Juno.

Preparing Trusted Firmware images

After building Trusted Firmware, the files bl1.bin and fip.bin need copying to the SOFTWARE/ directory of the Juno SD card.

Other Juno software information

Please visit the ARM Platforms Portal to get support and obtain any other Juno software information. Please also refer to the Juno Getting Started Guide to get more detailed information about the Juno ARM development platform and how to configure it.

Testing SYSTEM SUSPEND on Juno

The SYSTEM SUSPEND is a PSCI API which can be used to implement system suspend to RAM. For more details refer to section 5.16 of PSCI. To test system suspend on Juno, at the linux shell prompt, issue the following command:

echo +10 > /sys/class/rtc/rtc0/wakealarm
echo -n mem > /sys/power/state

The Juno board should suspend to RAM and then wakeup after 10 seconds due to wakeup interrupt from RTC.

Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved.