Align entire TF-A to use Arm in copyright header.
Change-Id: Ief9992169efdab61d0da6bd8c5180de7a4bc2244
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
TF-A code supports SMCCC spec version 1.4 while version is still kept
1.2. Bump up the version.
Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: Ie5476c4601bd504d3f3e8433e1d672ebd0a758b1
As per SMCCC spec Table 2.1 bit 23:17 must be zero (MBZ),
for all Fast Calls, when bit[31] == 1.
Adding this check to ensure SMC FIDs when get to the SMC handler
have these bits (23:17) cleared, if not capture and report them
as an unknown SMCs at the core.
Also the C runtime stack is copied to the stackpointer well in
advance, to leverage the existing el3_exit routine for unknown SMC.
Change-Id: I9972216db5ac164815011177945fb34dadc871b0
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
SMCCCv1.3 introduces the SVE hint bit added to the SMC FID (bit 16)
denoting that the world issuing an SMC doesn't expect the callee to
preserve the SVE state (FFR, predicates, Zn vector bits greater than
127). Update the generic SMC handler to copy the SVE hint bit state
to SMC flags and mask out the bit by default for the services called
by the standard dispatcher. It is permitted by the SMCCC standard to
ignore the bit as long as the SVE state is preserved. In any case a
callee must preserve the NEON state (FPCR/FPSR, Vn 128b vectors)
whichever the SVE hint bit state.
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I2b163ed83dc311b8f81f96b23c942829ae9fa1b5
Added a dummy DRTM setup function and also, introduced DRTM SMCs
handling as per DRTM spec [1]. Few basic SMCs are handled in this
change such as ARM_DRTM_SVC_VERSION and ARM_DRTM_SVC_FEATURES
that returns DRTM version and functions ids supported respectively,
and others are dummy for now.
[1]: https://developer.arm.com/documentation/den0113/latest
Signed-off-by: Manish V Badarkhe <manish.badarkhe@arm.com>
Signed-off-by: Lucian Paul-Trifu <lucian.paultrifu@gmail.com>
Change-Id: I8c7afe920c78e064cbab2298f59e6837c70ba8ff
FEAT_RME introduces two additional security states,
Root and Realm security states. This patch adds Realm
security state awareness to SMCCC helpers and entry point info
structure.
Signed-off-by: Zelalem Aweke <zelalem.aweke@arm.com>
Change-Id: I9cdefcc1aa71259b2de46e5fb62b28d658fa59bd
The definitions of SMCCC_ARCH_SOC_ID SoC version return bits are defined
in SMC Calling Convention [1]. Add the masks and shifts for JEP-106 bank
index, JEP-106 identification code, and Implementation defined SoC ID.
Add a macro to easily set JEP-106 fields.
[1] https://developer.arm.com/documentation/den0028/latest/
Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Change-Id: Iecbd09f6de6728de89dc746d2d1981a5a97a8ab7
Usually, C has no problem up-converting types to larger bit sizes. MISRA
rule 10.7 requires that you not do this, or be very explicit about this.
This resolves the following required rule:
bl1/aarch64/bl1_context_mgmt.c:81:[MISRA C-2012 Rule 10.7 (required)]<None>
The width of the composite expression "0U | ((mode & 3U) << 2U) | 1U |
0x3c0U" (32 bits) is less that the right hand operand
"18446744073709547519ULL" (64 bits).
This also resolves MISRA defects such as:
bl2/aarch64/bl2arch_setup.c:18:[MISRA C-2012 Rule 12.2 (required)]
In the expression "3U << 20", shifting more than 7 bits, the number
of bits in the essential type of the left expression, "3U", is
not allowed.
Further, MISRA requires that all shifts don't overflow. The definition of
PAGE_SIZE was (1U << 12), and 1U is 8 bits. This caused about 50 issues.
This fixes the violation by changing the definition to 1UL << 12. Since
this uses 32bits, it should not create any issues for aarch32.
This patch also contains a fix for a build failure in the sun50i_a64
platform. Specifically, these misra fixes removed a single and
instruction,
92407e73 and x19, x19, #0xffffffff
from the cm_setup_context function caused a relocation in
psci_cpus_on_start to require a linker-generated stub. This increased the
size of the .text section and caused an alignment later on to go over a
page boundary and round up to the end of RAM before placing the .data
section. This sectionn is of non-zero size and therefore causes a link
error.
The fix included in this reorders the functions during link time
without changing their ording with respect to alignment.
Change-Id: I76b4b662c3d262296728a8b9aab7a33b02087f16
Signed-off-by: Jimmy Brisson <jimmy.brisson@arm.com>
There was a collision between the name of the typedef in the CASSERT and
something else, so we make the name of the typedef unique to the
invocation of DEFFINE_SVC_UUID2 by appending the name that's passed into
the macro. This eliminates the following MISRA violation:
bl1/bl1_main.c:233:[MISRA C-2012 Rule 5.6 (required)] Identifier
"invalid_svc_uuid" is already used to represent a typedef.
This also resolves MISRA rule 5.9.
These renamings are as follows:
* tzram -> secram. This matches the function call name as it has
sec_mem in it's name
* fw_config_base -> config_base. This file does not mess with
hw_conig, so there's little chance of confusion
Change-Id: I8734ba0956140c8e29b89d0596d10d61a6ef351e
Signed-off-by: Jimmy Brisson <jimmy.brisson@arm.com>
Attempts to address MISRA compliance issues in BL1, BL2, and BL31 code.
Mainly issues like not using boolean expressions in conditionals,
conflicting variable names, ignoring return values without (void), adding
explicit casts, etc.
Change-Id: If1fa18ab621b9c374db73fa6eaa6f6e5e55c146a
Signed-off-by: John Powell <john.powell@arm.com>
From AArch64 state, arguments are passed in registers W0-W7(X0-X7)
and results are returned in W0-W7(X0-X7) for SMC32(SMC64) calls.
From AArch32 state, arguments are passed in registers R0-R7 and
results are returned in registers R0-R7 for SMC32 calls.
Most of the functions and macros already existed to support using
upto 8 registers for passing/returning parameters/results. Added
few helper macros for SMC calls from AArch32 state.
Link to the specification:
https://developer.arm.com/docs/den0028/c
Change-Id: I87976b42454dc3fc45c8343e9640aa78210e9741
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
NOTE: __ASSEMBLY__ macro is now deprecated in favor of __ASSEMBLER__.
All common C compilers predefine a macro called __ASSEMBLER__ when
preprocessing a .S file. There is no reason for TF-A to define it's own
__ASSEMBLY__ macro for this purpose instead. To unify code with the
export headers (which use __ASSEMBLER__ to avoid one extra dependency),
let's deprecate __ASSEMBLY__ and switch the code base over to the
predefined standard.
Change-Id: Id7d0ec8cf330195da80499c68562b65cb5ab7417
Signed-off-by: Julius Werner <jwerner@chromium.org>
This reverts commit 2f37046524 ("Add support for the SMC Calling
Convention 2.0").
SMCCC v2.0 is no longer required for SPM, and won't be needed in the
future. Removing it makes the SMC handling code less complicated.
The SPM implementation based on SPCI and SPRT was using it, but it has
been adapted to SMCCC v1.0.
Change-Id: I36795b91857b2b9c00437cfbfed04b3c1627f578
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Enforce full include path for includes. Deprecate old paths.
The following folders inside include/lib have been left unchanged:
- include/lib/cpus/${ARCH}
- include/lib/el3_runtime/${ARCH}
The reason for this change is that having a global namespace for
includes isn't a good idea. It defeats one of the advantages of having
folders and it introduces problems that are sometimes subtle (because
you may not know the header you are actually including if there are two
of them).
For example, this patch had to be created because two headers were
called the same way: e0ea0928d5 ("Fix gpio includes of mt8173 platform
to avoid collision."). More recently, this patch has had similar
problems: 46f9b2c3a2 ("drivers: add tzc380 support").
This problem was introduced in commit 4ecca33988 ("Move include and
source files to logical locations"). At that time, there weren't too
many headers so it wasn't a real issue. However, time has shown that
this creates problems.
Platforms that want to preserve the way they include headers may add the
removed paths to PLAT_INCLUDES, but this is discouraged.
Change-Id: I39dc53ed98f9e297a5966e723d1936d6ccf2fc8f
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
All identifiers, regardless of use, that start with two underscores are
reserved. This means they can't be used in header guards.
The style that this project is now to use the full name of the file in
capital letters followed by 'H'. For example, for a file called
"uart_example.h", the header guard is UART_EXAMPLE_H.
The exceptions are files that are imported from other projects:
- CryptoCell driver
- dt-bindings folders
- zlib headers
Change-Id: I50561bf6c88b491ec440d0c8385c74650f3c106e
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Casting a pointer to a struct uuid into a pointer to uint32_t may
result in a pointer that is not correctly aligned, which constitutes
an undefined behaviour. In the case of TF, this also generates a data
abort because alignment fault checking is enabled (through the SCTLR.A
bit).
This patch modifies the SMC_UUID_RET() macro to read the uuid
structure without any pointer aliasing. A helper function then
combines every set of 4 bytes into a 32-bit value suitable to be
returned through the x0-x3 registers.
This fixes a violation of MISRA rule 11.3.
Change-Id: I53ee73bb4cb332f4d8286055ceceb6f347caa080
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
RFC4122 defines that fields are stored in network order (big endian),
but TF-A stores them in machine order (little endian by default in TF-A).
We cannot change the future UUIDs that are already generated, but we can store
all the bytes using arrays and modify fiptool to generate the UUIDs with
the correct byte order.
Change-Id: I97be2d3168d91f4dee7ccfafc533ea55ff33e46f
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>
Due to differences in the bitfields of the SMC IDs, it is not possible
to support SMCCC 1.X and 2.0 at the same time.
The behaviour of `SMCCC_MAJOR_VERSION` has changed. Now, it is a build
option that specifies the major version of the SMCCC that the Trusted
Firmware supports. The only two allowed values are 1 and 2, and it
defaults to 1. The value of `SMCCC_MINOR_VERSION` is derived from it.
Note: Support for SMCCC v2.0 is an experimental feature to enable
prototyping of secure partition specifications. Support for this
convention is disabled by default and could be removed without notice.
Change-Id: I88abf9ccf08e9c66a13ce55c890edea54d9f16a7
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
When the source code says 'SMCC' it is talking about the SMC Calling
Convention. The correct acronym is SMCCC. This affects a few definitions
and file names.
Some files have been renamed (smcc.h, smcc_helpers.h and smcc_macros.S)
but the old files have been kept for compatibility, they include the
new ones with an ERROR_DEPRECATED guard.
Change-Id: I78f94052a502436fdd97ca32c0fe86bd58173f2f
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
According to the SMC Calling Convention (ARM DEN0028B):
The Unknown SMC Function Identifier is a sign-extended value of
(-1) that is returned in R0, W0 or X0 register.
The value wasn't sign-extended because it was defined as a 32-bit
unsigned value (0xFFFFFFFF).
SMC_PREEMPT has been redefined as -2 for the same reason.
NOTE: This might be a compatibility break for some AArch64 platforms
that don't follow the previous version of the SMCCC (ARM DEN0028A)
correctly. That document specifies that only the bottom 32 bits of the
returned value must be checked. If a platform relies on the top 32 bits
of the result being 0 (so that SMC_UNK is 0x00000000FFFFFFFF), it will
have to fix its code to comply with the SMCCC.
Change-Id: I7f7b109f6b30c114fe570aa0ead3c335383cb54d
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
SMCCC v1.1 comes with a relaxed calling convention for AArch64
callers. The caller only needs to save x0-x3 before doing an SMC
call.
This patch adds support for SMCCC_VERSION and SMCCC_ARCH_FEATURES.
Refer to "Firmware Interfaces for mitigating CVE_2017_5715 System
Software on Arm Systems"[0] for more information.
[0] https://developer.arm.com/-/media/developer/pdf/ARM%20DEN%200070A%20Firmware%20interfaces%20for%20mitigating%20CVE-2017-5715_V1.0.pdf
Change-Id: If5b1c55c17d6c5c7cb9c2c3ed355d3a91cdad0a9
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>
This patch uses the U() and ULL() macros for constants, to fix some
of the signed-ness defects flagged by the MISRA scanner.
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
To make software license auditing simpler, use SPDX[0] license
identifiers instead of duplicating the license text in every file.
NOTE: Files that have been imported by FreeBSD have not been modified.
[0]: https://spdx.org/
Change-Id: I80a00e1f641b8cc075ca5a95b10607ed9ed8761a
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
utils.h is included in various header files for the defines in it.
Some of the other header files only contain defines. This allows the
header files to be shared between host and target builds for shared defines.
Recently types.h has been included in utils.h as well as some function
prototypes.
Because of the inclusion of types.h conflicts exist building host tools
abd these header files now. To solve this problem,
move the defines to utils_def.h and have this included by utils.h and
change header files to only include utils_def.h and not pick up the new
types.h being introduced.
FixesARM-software/tf-issues#461
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Remove utils_def.h from utils.h
This patch removes utils_def.h from utils.h as it is not required.
And also makes a minor change to ensure Juno platform compiles.
Change-Id: I10cf1fb51e44a8fa6dcec02980354eb9ecc9fa29
Since Issue B (November 2016) of the SMC Calling Convention document
standard SMC calls are renamed to yielding SMC calls to help avoid
confusion with the standard service SMC range, which remains unchanged.
http://infocenter.arm.com/help/topic/com.arm.doc.den0028b/ARM_DEN0028B_SMC_Calling_Convention.pdf
This patch adds a new define for yielding SMC call type and deprecates
the current standard SMC call type. The tsp is migrated to use this new
terminology and, additionally, the documentation and code comments are
updated to use this new terminology.
Change-Id: I0d7cc0224667ee6c050af976745f18c55906a793
Signed-off-by: David Cunado <david.cunado@arm.com>
SMC_RET0 should only be used when the SMC code works as a function that
returns void. If the code of the SMC uses SMC_RET1 to return a value to
signify success and doesn't return anything in case of an error (or the
other way around) SMC_RET1 should always be used to return clearly
identifiable values.
This patch fixes two cases in which the code used SMC_RET0 instead of
SMC_RET1.
It also introduces the define SMC_OK to use when an SMC must return a
value to tell that it succeeded, the same way as SMC_UNK is used in case
of failure.
Change-Id: Ie4278b51559e4262aced13bbde4e844023270582
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
With GCC 6.2 compiler, more C undefined behaviour is being flagged as
warnings, which result in build errors in ARM TF build.
The specific issue that this patch resolves is the use of (1 << 31),
which is predominantly used in case statements, where 1 is represented
as a signed int. When shifted to msb the behaviour is undefined.
The resolution is to specify 1 as an unsigned int using a convenience
macro ULL(). A duplicate macro MAKE_ULL() is replaced.
FixesARM-software/tf-issues#438
Change-Id: I08e3053bbcf4c022ee2be33a75bd0056da4073e1
Signed-off-by: David Cunado <david.cunado@arm.com>
This patch introduces the PSCI Library interface. The major changes
introduced are as follows:
* Earlier BL31 was responsible for Architectural initialization during cold
boot via bl31_arch_setup() whereas PSCI was responsible for the same during
warm boot. This functionality is now consolidated by the PSCI library
and it does Architectural initialization via psci_arch_setup() during both
cold and warm boots.
* Earlier the warm boot entry point was always `psci_entrypoint()`. This was
not flexible enough as a library interface. Now PSCI expects the runtime
firmware to provide the entry point via `psci_setup()`. A new function
`bl31_warm_entrypoint` is introduced in BL31 and the previous
`psci_entrypoint()` is deprecated.
* The `smc_helpers.h` is reorganized to separate the SMC Calling Convention
defines from the Trusted Firmware SMC helpers. The former is now in a new
header file `smcc.h` and the SMC helpers are moved to Architecture specific
header.
* The CPU context is used by PSCI for context initialization and
restoration after power down (PSCI Context). It is also used by BL31 for SMC
handling and context management during Normal-Secure world switch (SMC
Context). The `psci_smc_handler()` interface is redefined to not use SMC
helper macros thus enabling to decouple the PSCI context from EL3 runtime
firmware SMC context. This enables PSCI to be integrated with other runtime
firmware using a different SMC context.
NOTE: With this patch the architectural setup done in `bl31_arch_setup()`
is done as part of `psci_setup()` and hence `bl31_platform_setup()` will be
invoked prior to architectural setup. It is highly unlikely that the platform
setup will depend on architectural setup and cause any failure. Please be
be aware of this change in sequence.
Change-Id: I7f497a08d33be234bbb822c28146250cb20dab73
This patch fixes some coding guideline warnings reported by the checkpatch
script. Only files related to upcoming feature development have been fixed.
Change-Id: I26fbce75c02ed62f00493ed6c106fe7c863ddbc5
The upcoming Firmware Update feature needs transitioning across
Secure/Normal worlds to complete the FWU process and hence requires
context management code to perform this task.
Currently context management code is part of BL31 stage only.
This patch moves the code from (include)/bl31 to (include)/common.
Some function declarations/definitions and macros have also moved
to different files to help code sharing.
Change-Id: I3858b08aecdb76d390765ab2b099f457873f7b0c
This patch implements the PSCI_FEATURES function which is a mandatory
API in the PSCI 1.0 specification. A capability variable is
constructed during initialization by examining the plat_pm_ops and
spd_pm_ops exported by the platform and the Secure Payload Dispatcher.
This is used by the PSCI FEATURES function to determine which
PSCI APIs are supported by the platform.
Change-Id: I147ffc1bd5d90b469bd3cc4bbe0a20e95c247df7
The crash reporting support and early initialisation of the
cpu_data allow the runtime_exception vectors to be used from
the start in BL3-1, removing the need for the additional
early_exception vectors and 2KB of code from BL3-1.
Change-Id: I5f8997dabbaafd8935a7455910b7db174a25d871
This patch prepares the per-cpu pointer cache for wider use by:
* renaming the structure to cpu_data and placing in new header
* providing accessors for this CPU, or other CPUs
* splitting the initialization of the TPIDR pointer from the
initialization of the cpu_data content
* moving the crash stack initialization to a crash stack function
* setting the TPIDR pointer very early during boot
Change-Id: Icef9004ff88f8eb241d48c14be3158087d7e49a3
Implements support for Non Secure Interrupts preempting the
Standard SMC call in EL1. Whenever an IRQ is trapped in the
Secure world we securely handover to the Normal world
to process the interrupt. The normal world then issues
"resume" smc call to resume the previous interrupted SMC call.
FixesARM-software/tf-issues#105
Change-Id: I72b760617dee27438754cdfc9fe9bcf4cc024858
This patch adds support in the TSPD for registering a handler for
S-EL1 interrupts. This handler ferries the interrupts generated in the
non-secure state to the TSP at 'tsp_fiq_entry'. Support has been added
to the smc handler to resume execution in the non-secure state once
interrupt handling has been completed by the TSP.
There is also support for resuming execution in the normal world if
the TSP receives a EL3 interrupt. This code is currently unused.
Change-Id: I816732595a2635e299572965179f11aa0bf93b69
This patch implements the register reporting when unhandled exceptions are
taken in BL3-1. Unhandled exceptions will result in a dump of registers
to the console, before halting execution by that CPU. The Crash Stack,
previously called the Exception Stack, is used for this activity.
This stack is used to preserve the CPU context and runtime stack
contents for debugging and analysis.
This also introduces the per_cpu_ptr_cache, referenced by tpidr_el3,
to provide easy access to some of BL3-1 per-cpu data structures.
Initially, this is used to provide a pointer to the Crash stack.
panic() now prints the the error file and line number in Debug mode
and prints the PC value in release mode.
The Exception Stack is renamed to Crash Stack with this patch.
The original intention of exception stack is no longer valid
since we intend to support several valid exceptions like IRQ
and FIQ in the trusted firmware context. This stack is now
utilized for dumping and reporting the system state when a
crash happens and hence the rename.
FixesARM-software/tf-issues#79 Improve reporting of unhandled exception
Change-Id: I260791dc05536b78547412d147193cdccae7811a
Reduce the number of header files included from other header
files as much as possible without splitting the files. Use forward
declarations where possible. This allows removal of some unnecessary
"#ifndef __ASSEMBLY__" statements.
Also, review the .c and .S files for which header files really need
including and reorder the #include statements alphabetically.
FixesARM-software/tf-issues#31
Change-Id: Iec92fb976334c77453e010b60bcf56f3be72bd3e
Add tag names to all unnamed structs in header files. This
allows forward declaration of structs, which is necessary to
reduce header file nesting (to be implemented in a subsequent
commit).
Also change the typedef names across the codebase to use the _t
suffix to be more conformant with the Linux coding style. The
coding style actually prefers us not to use typedefs at all but
this is considered a step too far for Trusted Firmware.
Also change the IO framework structs defintions to use typedef'd
structs to be consistent with the rest of the codebase.
Change-Id: I722b2c86fc0d92e4da3b15e5cab20373dd26786f
Move the BL function prototypes out of arch.h and into the
appropriate header files to allow more efficient header file
inclusion. Create new BL private header files where there is no
sensible existing header file.
Change-Id: I45f3e10b72b5d835254a6f25a5e47cf4cfb274c3
Separate out the CASSERT macro out of bl_common.h into its own
header to allow more efficient header inclusion.
Change-Id: I291be0b6b8f9879645e839a8f0dd1ec9b3db9639
Move almost all system include files to a logical sub-directory
under ./include. The only remaining system include directories
not under ./include are specific to the platform. Move the
corresponding source files to match the include directory
structure.
Also remove pm.h as it is no longer used.
Change-Id: Ie5ea6368ec5fad459f3e8a802ad129135527f0b3
This patch implements ARM Standard Service as a runtime service and adds
support for call count, UID and revision information SMCs. The existing
PSCI implementation is subsumed by the Standard Service calls and all
PSCI calls are therefore dispatched by the Standard Service to the PSCI
handler.
At present, PSCI is the only specification under Standard Service. Thus
call count returns the number of PSCI calls implemented. As this is the
initial implementation, a revision number of 0.1 is returned for call
revision.
FixesARM-software/tf-issues#62
Change-Id: I6d4273f72ad6502636efa0f872e288b191a64bc1
This patch uses the reworked exception handling support to handle
runtime service requests through SMCs following the SMC calling
convention. This is a giant commit since all the changes are
inter-related. It does the following:
1. Replace the old exception handling mechanism with the new one
2. Enforce that SP_EL0 is used C runtime stacks.
3. Ensures that the cold and warm boot paths use the 'cpu_context'
structure to program an ERET into the next lower EL.
4. Ensures that SP_EL3 always points to the next 'cpu_context'
structure prior to an ERET into the next lower EL
5. Introduces a PSCI SMC handler which completes the use of PSCI as a
runtime service
Change-Id: I661797f834c0803d2c674d20f504df1b04c2b852
Co-authored-by: Achin Gupta <achin.gupta@arm.com>
This patch introduces the reworked exception handling logic which lays
the foundation for accessing runtime services in later patches. The
type of an exception has a greater say in the way it is
handled. SP_EL3 is used as the stack pointer for:
1. Determining the type of exception and handling the unexpected ones
on the exception stack
2. Saving and restoring the essential general purpose and system
register state after exception entry and prior to exception exit.
SP_EL0 is used as the stack pointer for handling runtime service
requests e.g. SMCs. A new structure for preserving general purpose
register state has been added to the 'cpu_context' structure. All
assembler ensures that it does not use callee saved registers
(x19-x29). The C runtime preserves them across functions calls. Hence
EL3 code does not have to save and restore them explicitly.
Since the exception handling framework has undergone substantial change,
the changes have been kept in separate files to aid readability. These
files will replace the existing ones in subsequent patches.
Change-Id: Ice418686592990ff7a4260771e8d6676e6c8c5ef