The interrupt handling routine in BL3-1 expects a cookie as its last
parameter which was not being passed when invoking the interrupt
handler in BL3-1. This patch fixes that by passing a dummy cookie
parameter in the x3 register.
FixesARM-software/tf-issues#171
Change-Id: Ic98abbbd9f849e6f1c55343e865b5e0a4904a1c5
At present the arguments for BL3-3 in the entry_point_info
structure are not being transferred to X0-X7 before starting
execution of this image
This patch saves the args for BL3-3 into cpu context used
for its entry
FixesARM-software/tf-issues#172
Change-Id: I001b4b9bff6a264336f0d01d377619ae719f928b
Rename the ic_* platform porting functions to plat_ic_* to be
consistent with the other functions in platform.h. Also rename
bl31_get_next_image_info() to bl31_plat_get_next_image_ep_info()
and remove the duplicate declaration in bl31.h.
Change-Id: I4851842069d3cff14c0a468daacc0a891a7ede84
Some platform porting functions were in BL specific header files.
These have been moved to platform.h so that all porting functions
are in the same place. The functions are now grouped by BL.
Obsolete BL headers files have been removed.
Also, the weak declaration of the init_bl2_mem_layout() function
has been moved out the header file and into the source file
(bl_common.c) using the more succinct #pragma syntax. This
mitigates the risk of 2 weak definitions being created and the
wrong one being picked up by the compiler.
Change-Id: Ib19934939fd755f3e5a5a5bceec88da684308a83
Previously, platform.h contained many declarations and definitions
used for different purposes. This file has been split so that:
* Platform definitions used by common code that must be defined
by the platform are now in platform_def.h. The exact include
path is exported through $PLAT_INCLUDES in the platform makefile.
* Platform definitions specific to the FVP platform are now in
/plat/fvp/fvp_def.h.
* Platform API declarations specific to the FVP platform are now
in /plat/fvp/fvp_private.h.
* The remaining platform API declarations that must be ported by
each platform are still in platform.h but this file has been
moved to /include/plat/common since this can be shared by all
platforms.
Change-Id: Ieb3bb22fbab3ee8027413c6b39a783534aee474a
Currently the platform code gets to define the base address of each
boot loader image. However, the linker scripts couteract this
flexibility by enforcing a fixed overall layout of the different
images. For example, they require that the BL3-1 image sits below
the BL2 image. Choosing BL3-1 and BL2 base addresses in such a way
that it violates this constraint makes the build fail at link-time.
This patch requires the platform code to now define a limit address
for each image. The linker scripts check that the image fits within
these bounds so they don't rely anymore on the position of a given
image in regard to the others.
FixesARM-software/tf-issues#163
Change-Id: I8c108646825da19a6a8dfb091b613e1dd4ae133c
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 a common handler for FIQ and IRQ exceptions in the
BL3-1 runtime exception vector table. This function determines the
interrupt type and calls its handler. A crash is reported if an
inconsistency in the interrupt management framework is detected. In
the event of a spurious interrupt, execution resumes from the
instruction where the interrupt was generated.
This patch also removes 'cm_macros.S' as its contents have been moved
to 'runtime_exceptions.S'
Change-Id: I3c85ecf8eaf43a3fac429b119ed0bd706d2e2093
This patch introduces a framework for registering interrupts routed to
EL3. The interrupt routing model is governed by the SCR_EL3.IRQ and
FIQ bits and the security state an interrupt is generated in. The
framework recognizes three type of interrupts depending upon which
exception level and security state they should be handled in
i.e. Secure EL1 interrupts, Non-secure interrupts and EL3
interrupts. It provides an API and macros that allow a runtime service
to register an handler for a type of interrupt and specify the routing
model. The framework validates the routing model and uses the context
management framework to ensure that it is applied to the SCR_EL3 prior
to entry into the target security state. It saves the handler in
internal data structures. An API is provided to retrieve the handler
when an interrupt of a particular type is asserted. Registration is
expected to be done once by the primary CPU. The same handler and
routing model is used for all CPUs.
Support for EL3 interrupts will be added to the framework in the
future. A makefile flag has been added to allow the FVP port choose
between ARM GIC v2 and v3 support in EL3. The latter version is
currently unsupported.
A framework for handling interrupts in BL3-1 will be introduced in
subsequent patches. The default routing model in the absence of any
handlers expects no interrupts to be routed to EL3.
Change-Id: Idf7c023b34fcd4800a5980f2bef85e4b5c29e649
This patch adds an API to write to any bit in the SCR_EL3 member of
the 'cpu_context' structure of the current CPU for a specified
security state. This API will be used in subsequent patches which
introduce interrupt management in EL3 to specify the interrupt routing
model when execution is not in EL3.
It also renames the cm_set_el3_elr() function to cm_set_elr_el3()
which is more in line with the system register name being targeted by
the API.
Change-Id: I310fa7d8f827ad3f350325eca2fb28cb350a85ed
This change adds optional reset vector support to BL3-1
which means BL3-1 entry point can detect cold/warm boot,
initialise primary cpu, set up cci and mail box.
When using BL3-1 as a reset vector it is assumed that
the BL3-1 platform code can determine the location of
the BL3-2 images, or load them as there are no parameters
that can be passed to BL3-1 at reset.
It also fixes the incorrect initialisation of mailbox
registers on the FVP platform
This feature can be enabled by building the code with
make variable RESET_TO_BL31 set as 1
FixesARM-software/TF-issues#133FixesARM-software/TF-issues#20
Change-Id: I4e23939b1c518614b899f549f1e8d412538ee570
The issues addressed in this patch are:
1. Remove meminfo_t from the common interfaces in BL3-x,
expecting that platform code will find a suitable mechanism
to determine the memory extents in these images and provide
it to the BL3-x images.
2. Remove meminfo_t and bl31_plat_params_t from all FVP BL3-x
code as the images use link-time information to determine
memory extents.
meminfo_t is still used by common interface in BL1/BL2 for
loading images
Change-Id: I4e825ebf6f515b59d84dc2bdddf6edbf15e2d60f
This patch is based on spec published at
https://github.com/ARM-software/tf-issues/issues/133
It rearranges the bl31_args struct into
bl31_params and bl31_plat_params which provide the
information needed for Trusted firmware and platform
specific data via x0 and x1
On the FVP platform BL3-1 params and BL3-1 plat params
and its constituents are stored at the start of TZDRAM.
The information about memory availability and size for
BL3-1, BL3-2 and BL3-3 is moved into platform specific data.
Change-Id: I8b32057a3d0dd3968ea26c2541a0714177820da9
This patch reworks the handover interface from: BL1 to BL2 and
BL2 to BL3-1. It removes the raise_el(), change_el(), drop_el()
and run_image() functions as they catered for code paths that were
never exercised.
BL1 calls bl1_run_bl2() to jump into BL2 instead of doing the same
by calling run_image(). Similarly, BL2 issues the SMC to transfer
execution to BL3-1 through BL1 directly. Only x0 and x1 are used
to pass arguments to BL31. These arguments and parameters for
running BL3-1 are passed through a reference to a
'el_change_info_t' structure. They were being passed value in
general purpose registers earlier.
Change-Id: Id4fd019a19a9595de063766d4a66295a2c9307e1
At present, non-secure timer register contents are saved and restored as
part of world switch by BL3-1. This effectively means that the
non-secure timer stops, and non-secure timer interrupts are prevented
from asserting until BL3-1 switches back, introducing latency for
non-secure services. Often, secure world might depend on alternate
sources for secure interrupts (secure timer or platform timer) instead
of non-secure timers, in which case this save and restore is
unnecessary.
This patch introduces a boolean build-time configuration NS_TIMER_SWITCH
to choose whether or not to save and restore non-secure timer registers
upon world switch. The default choice is made not to save and restore
them.
FixesARM-software/tf-issues#148
Change-Id: I1b9d623606acb9797c3e0b02fb5ec7c0a414f37e
SCR_EL3.RW was not updated immediately before exiting bl31_main() and
running BL3-3. If a AArch32 Secure-EL1 Payload had just been
initialised, then the SCR_EL3.RW bit would be left indicating a
32-bit BL3-3, which may not be correct.
This patch explicitly sets SCR_EL3.RW appropriately based on the
provided SPSR_EL3 value for the BL3-3 image.
FixesARM-software/tf-issues#126
Change-Id: Ic7716fe8bc87e577c4bfaeb46702e88deedd9895
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
Previously exception handlers in BL3-1, X19-X29 were not saved
and restored on every SMC/trap into EL3. Instead these registers
were 'saved as needed' as a side effect of the A64 ABI used by the C
compiler.
That approach failed when world switching but was not visible
with the TSP/TSPD code because the TSP is 64-bit, did not
clobber these registers when running and did not support pre-emption
by normal world interrupts. These scenarios showed
that the values in these registers can be passed through a world
switch, which broke the normal and trusted world assumptions
about these registers being preserved.
The Ideal solution saves and restores these registers when a
world switch occurs - but that type of implementation is more complex.
So this patch always saves and restores these registers on entry and
exit of EL3.
FixesARM-software/tf-issues#141
Change-Id: I9a727167bbc594454e81cf78a97ca899dfb11c27
Instead of using the system register helper functions to read
or write system registers, assembler coded functions should
use MRS/MSR instructions. This results in faster and more
compact code.
This change replaces all usage of the helper functions with
direct register accesses.
Change-Id: I791d5f11f257010bb3e6a72c6c5ab8779f1982b3
The current code does not always use data and instruction
barriers as required by the architecture and frequently uses
barriers excessively due to their inclusion in all of the
write_*() helper functions.
Barriers should be used explicitly in assembler or C code
when modifying processor state that requires the barriers in
order to enable review of correctness of the code.
This patch removes the barriers from the helper functions and
introduces them as necessary elsewhere in the code.
PORTING NOTE: check any port of Trusted Firmware for use of
system register helper functions for reliance on the previous
barrier behaviour and add explicit barriers as necessary.
FixesARM-software/tf-issues#92
Change-Id: Ie63e187404ff10e0bdcb39292dd9066cb84c53bf
SCTLR_EL3.EE is being configured too late in bl1_arch_setup() and
bl31_arch_setup() after data accesses have already occured on
the cold and warm boot paths.
This control bit must be configured immediately on CPU reset to
match the endian state of the firmware (little endian).
FixesARM-software/tf-issues#145
Change-Id: Ie12e46fbbed6baf024c30beb50751591bb8c8655
Update code base to remove variables from the .data section,
mainly by using const static data where possible and adding
the const specifier as required. Most changes are to the IO
subsystem, including the framework APIs. The FVP power
management code is also affected.
Delay initialization of the global static variable,
next_image_type in bl31_main.c, until it is realy needed.
Doing this moves the variable from the .data to the .bss
section.
Also review the IO interface for inconsistencies, using
uintptr_t where possible instead of void *. Remove the
io_handle and io_dev_handle typedefs, which were
unnecessary, replacing instances with uintptr_t.
FixesARM-software/tf-issues#107.
Change-Id: I085a62197c82410b566e4698e5590063563ed304
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
Remove all usage of the vpath keyword in makefiles as it was prone
to mistakes. Specify the relative paths to source files instead.
Also reorder source files in makefiles alphabetically.
FixesARM-software/tf-issues#121
Change-Id: Id15f60655444bae60e0e2165259efac71a50928b
Make codebase consistent in its use of #include "" syntax for
user includes and #include <> syntax for system includes.
FixesARM-software/tf-issues#65
Change-Id: If2f7c4885173b1fd05ac2cde5f1c8a07000c7a33
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
The BL images share common stack management code which provides
one coherent and one cacheable stack for every CPU. BL1 and BL2
just execute on the primary CPU during boot and do not require
the additional CPU stacks. This patch provides separate stack
support code for UP and MP images, substantially reducing the
RAM usage for BL1 and BL2 for the FVP platform.
This patch also provides macros for declaring stacks and
calculating stack base addresses to improve consistency where
this has to be done in the firmware.
The stack allocation source files are now included via
platform.mk rather than the common BLx makefiles. This allows
each platform to select the appropriate MP/UP stack support
for each BL image.
Each platform makefile must be updated when including this
commit.
FixesARM-software/tf-issues#76
Change-Id: Ia251f61b8148ffa73eae3f3711f57b1ffebfa632
BL3-1 architecture setup code programs the system counter frequency
into the CNTFRQ_EL0 register. This frequency is defined by the
platform, though. This patch introduces a new platform hook that
the architecture setup code can call to retrieve this information.
In the ARM FVP port, this returns the first entry of the frequency
modes table from the memory mapped generic timer.
All system counter setup code has been removed from BL1 as some
platforms may not have initialized the system counters at this stage.
The platform specific settings done exclusively in BL1 have been moved
to BL3-1. In the ARM FVP port, this consists in enabling and
initializing the System level generic timer. Also, the frequency change
request in the counter control register has been set to 0 to make it
explicit it's using the base frequency. The CNTCR_FCREQ() macro has been
fixed in this context to give an entry number rather than a bitmask.
In future, when support for firmware update is implemented, there
is a case where BL1 platform specific code will need to program
the counter frequency. This should be implemented at that time.
This patch also updates the relevant documentation.
It properly fixesARM-software/tf-issues#24
Change-Id: If95639b279f75d66ac0576c48a6614b5ccb0e84b
This reverts commit 1c297bf015
because it introduced a bug: the CNTFRQ_EL0 register was no
longer programmed by all CPUs. bl31_platform_setup() function
is invoked only in the cold boot path and consequently only
on the primary cpu.
A subsequent commit will correctly implement the necessary changes
to the counter frequency setup code.
FixesARM-software/tf-issues#125
Conflicts:
docs/firmware-design.md
plat/fvp/bl31_plat_setup.c
Change-Id: Ib584ad7ed069707ac04cf86717f836136ad3ab54
This extends the --gc-sections behaviour to the many assembler
support functions in the firmware images by placing each function
into its own code section. This is achieved by creating a 'func'
macro used to declare each function label.
FixesARM-software/tf-issues#80
Change-Id: I301937b630add292d2dec6d2561a7fcfa6fec690
All common functions are being built into all binary images,
whether or not they are actually used. This change enables the
use of -ffunction-sections, -fdata-sections and --gc-sections
in the compiler and linker to remove unused code and data from
the images.
Change-Id: Ia9f78c01054ac4fa15d145af38b88a0d6fb7d409
bl1/aarch64/early_exceptions.S used to be re-used by BL2, BL3-1 and
BL3-2. There was some early SMC handling code in there that was not
required by the other bootloader stages. Therefore this patch
introduces an even simpler exception vector source file for BL2,
BL3-1 and BL3-2.
FixesARM-software/tf-issues#38
Change-Id: I0244b80e9930b0f8035156a0bf91cc3e9a8f995d
Each ARM Trusted Firmware image should know in which EL it is running
and it should use the corresponding register directly instead of reading
currentEL and knowing which asm register to read/write
Change-Id: Ief35630190b6f07c8fbb7ba6cb20db308f002945
At present, the entry point for each BL image is specified via the
Makefiles and provided on the command line to the linker. When using a
link script the entry point should rather be specified via the ENTRY()
directive in the link script.
This patch updates linker scripts of all BL images to specify the entry
point using the ENTRY() directive. It also removes the --entry flag
passed to the linker through Makefile.
Fixes issue ARM-software/tf-issues#66
Change-Id: I1369493ebbacea31885b51185441f6b628cf8da0
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
At present, bl1_arch_setup() and bl31_arch_setup() program the counter
frequency using a value from the memory mapped generic timer. The
generic timer however is not necessarily present on all ARM systems
(although it is architected to be present on all server systems).
This patch moves the timer setup to platform-specific code and updates
the relevant documentation. Also, CNTR.FCREQ is set as the specification
requires the bit corresponding to the counter's frequency to be set when
enabling. Since we intend to use the base frequency, set bit 8.
FixesARM-software/tf-issues#24
Change-Id: I32c52cf882253e01f49056f47c58c23e6f422652
So it updates each time a bootloader changes, not just when bl*_main.c
files are recompiled.
FixesARM-software/tf-issues#33
Change-Id: Ie8e1a7bd7e1913d2e96ac268606284f76af8c5ab
Signed-off-by: Jon Medhurst <tixy@linaro.org>
This change requires all platforms to now specify a list of source files
rather than object files.
New source files should preferably be specified by using the path as
well and we should add this in the future for all files so we can remove
use of vpath. This is desirable because vpath hides issues like the fact
that BL2 currently pulls in a BL1 file bl1/aarch64/early_exceptions.S
and if in the future we added bl2/aarch64/early_exceptions.S then it's
likely only one of the two version would be used for both bootloaders.
This change also removes the 'dump' build target and simply gets
bootloaders to always generate a dump file. At the same time the -x
option is added so the section headers and symbols table are listed.
FixesARM-software/tf-issues#11
Change-Id: Ie38f7be76fed95756c8576cf3f3ea3b7015a18dc
Signed-off-by: Jon Medhurst <tixy@linaro.org>
The BL31 and BL2 linker scripts ended up having duplicate descriptions
for xlat_tables section. This patch removes those duplicate
descriptions.
Change-Id: Ibbdda0902c57fca5ea4e91e0baefa6df8f0a9bb1
At present SPD power management hooks and BL3-2 entry are implemented
using weak references. This would have the handlers bound and registered
with the core framework at build time, but leaves them dangling if a
service fails to initialize at runtime.
This patch replaces implementation by requiring runtime handlers to
register power management and deferred initialization hooks with the
core framework at runtime. The runtime services are to register the
hooks only as the last step, after having all states successfully
initialized.
Change-Id: Ibe788a2a381ef39aec1d4af5ba02376e67269782
This patch implements a set of handlers in the SPD which are called by
the PSCI runtime service upon receiving a power management
operation. These handlers in turn pass control to the Secure Payload
image if required before returning control to PSCI. This ensures that
the Secure Payload has complete visibility of all power transitions in
the system and can prepare accordingly.
Change-Id: I2d1dba5629b7cf2d53999d39fe807dfcf3f62fe2
This patch creates a 'services' directory and moves the PSCI under
it. Other runtime services e.g. the Secure Payload Dispatcher service
will be placed under the same directory in the future.
Also fixes issue ARM-software/tf-issues#12
Change-Id: I187f83dcb660b728f82155d91882e961d2255068
This patch factors out the ARM FVP specific code to create MMU
translation tables so that it is possible for a boot loader stage to
create a different set of tables instead of using the default ones.
The default translation tables are created with the assumption that
the calling boot loader stage executes out of secure SRAM. This might
not be true for the BL3_2 stage in the future.
A boot loader stage can define the `fill_xlation_tables()` function as
per its requirements. It returns a reference to the level 1
translation table which is used by the common platform code to setup
the TTBR_EL3.
This patch is a temporary solution before a larger rework of
translation table creation logic is introduced.
Change-Id: I09a075d5da16822ee32a411a9dbe284718fb4ff6
This patch adds the following support to the BL3-1 stage:
1. BL3-1 allows runtime services to specify and determine the security
state of the next image after BL3-1. This has been done by adding
the `bl31_set_next_image_type()` & `bl31_get_next_image_type()`
apis. The default security state is non-secure. The platform api
`bl31_get_next_image_info()` has been modified to let the platform
decide which is the next image in the desired security state.
2. BL3-1 exports the `bl31_prepare_next_image_entry()` function to
program entry into the target security state. It uses the apis
introduced in 1. to do so.
3. BL3-1 reads the information populated by BL2 about the BL3-2 image
into its internal data structures.
4. BL3-1 introduces a weakly defined reference `bl32_init()` to allow
initialisation of a BL3-2 image. A runtime service like the Secure
payload dispatcher will define this function if present.
Change-Id: Icc46dcdb9e475ce6575dd3f9a5dc7a48a83d21d1
This patch reworks BL2 to BL3-1 hand over interface by introducing a
composite structure (bl31_args) that holds the superset of information
that needs to be passed from BL2 to BL3-1.
- The extents of secure memory available to BL3-1
- The extents of memory available to BL3-2 (not yet implemented) and
BL3-3
- Information to execute BL3-2 (not yet implemented) and BL3-3 images
This patch also introduces a new platform API (bl2_get_bl31_args_ptr)
that needs to be implemented by the platform code to export reference to
bl31_args structure which has been allocated in platform-defined memory.
The platform will initialize the extents of memory available to BL3-3
during early platform setup in bl31_args structure. This obviates the
need for bl2_get_ns_mem_layout platform API.
BL2 calls the bl2_get_bl31_args_ptr function to get a reference to
bl31_args structure. It uses the 'bl33_meminfo' field of this structure
to load the BL3-3 image. It sets the entry point information for the
BL3-3 image in the 'bl33_image_info' field of this structure. The
reference to this structure is passed to the BL3-1 image.
Also fixes issue ARM-software/tf-issues#25
Change-Id: Ic36426196dd5ebf89e60ff42643bed01b3500517
This patch adds guards so that an exception vector exceeding 32
instructions will generate a compile-time error. This keeps the
exception handlers in check from spilling over.
Change-Id: I7aa56dd0071a333664e2814c656d3896032046fe
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
Soby Mathew
Vikram Kanigiri
Dan Handley
Sandrine Bailleux
Achin Gupta
Jeenu Viswambharan
Andrew Thoelke
Jon Medhurst