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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.

Fixes ARM-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.

Fixes ARM-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).

Fixes ARM-software/tf-issues#145

Change-Id: Ie12e46fbbed6baf024c30beb50751591bb8c8655

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.

Fixes ARM-software/tf-issues#31

Change-Id: Iec92fb976334c77453e010b60bcf56f3be72bd3e

Make codebase consistent in its use of #include "" syntax for
user includes and #include <> syntax for system includes.

Fixes ARM-software/tf-issues#65

Change-Id: If2f7c4885173b1fd05ac2cde5f1c8a07000c7a33

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.

Fixes ARM-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 fixes ARM-software/tf-issues#24

Change-Id: If95639b279f75d66ac0576c48a6614b5ccb0e84b

This reverts commit 1c297bf0
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.

Fixes ARM-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.

Fixes ARM-software/tf-issues#80

Change-Id: I301937b630add292d2dec6d2561a7fcfa6fec690

Fixes ARM-software/tf-issues#70

Change-Id: I7f024f173fbdecd315076f528b05d6295aff7276

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, 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.

Fixes ARM-software/tf-issues#24

Change-Id: I32c52cf882253e01f49056f47c58c23e6f422652

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

This patch introduces functions for saving and restoring shared system
registers between secure and non-secure EL1 exception levels, VFP
registers and essential EL3 system register and other state. It also
defines the 'cpu_context' data structure which will used for saving and
restoring execution context for a given security state. These functions
will allow runtime services like PSCI and Secure payload dispatcher to
implement logic for switching between the secure and non-secure states.

The save and restore functions follow AArch64 PCS and only use
caller-saved temporary registers.

Change-Id: I8ee3aaa061d3caaedb28ae2c5becb9a206b6fd74

This patch ensures that VBAR_EL3 points to the simple stack-less
'early_exceptions' when the C runtime stack is not correctly setup to
use the more complex 'runtime_exceptions'. It is initialised to
'runtime_exceptions' once this is done.

This patch also moves all exception vectors into a '.vectors' section
and modifies linker scripts to place all such sections together. This
will minimize space wastage from alignment restrictions.

Change-Id: I8c3e596ea3412c8bd582af9e8d622bb1cb2e049d

Ctags seem to have a problem with generating tags for assembler symbols
when a comment immediately follows an assembly label.

This patch inserts a single space character between the label
definition and the following comments to help ctags.

The patch is generated by the command:

  git ls-files -- \*.S | xargs sed -i 's/^\([^:]\+\):;/\1: ;/1'

Change-Id: If7a3c9d0f51207ea033cc8b8e1b34acaa0926475

Traps when accessing architectural features are disabled by clearing bits
in CPTR_EL3 during early boot, including accesses to floating point
registers. The value of this register was previously undetermined, causing
unwanted traps to EL3. Future EL3 code (for example, context save/restore
code) may use floating point registers, although they are not used by current
code.

Also, the '-mgeneral-regs-only' flag is enabled in the GCC settings to
prevent generation of code that uses floating point registers.

Change-Id: I9a03675f6387bbbee81a6f2c9ccf81150db03747

Change-Id: Ic7fb61aabae1d515b9e6baf3dd003807ff42da60

ns_entry_info used to be a per-cpu array.  This is a waste of space
because it is only accessed by the primary CPU on the cold boot path.
This patch reduces ns_entry_info to a single-cpu area.

Change-Id: I647c70c4e76069560f1aaad37a1d5910f56fba4c

RUN_IMAGE constant is used by all bootloader stages.

Change-Id: I1b4e28d8fcf3ad1363f202c859f5efab0f320efe

The runtime exception handling assembler code used magic numbers for
saving and restoring the general purpose register context on stack
memory. The memory is interpreted as a 'gp_regs' structure and the
magic numbers are offsets to members of this structure. This patch
replaces the magic number offsets with constants. It also adds compile
time assertions to prevent an incorrect assembler view of this
structure.

Change-Id: Ibf125bfdd62ba3a33e58c5f1d71f8c229720781c

- Add instructions for contributing to ARM Trusted Firmware.

- Update copyright text in all files to acknowledge contributors.

Change-Id: I9311aac81b00c6c167d2f8c889aea403b84450e5

This patch makes sure the C runtime environment is properly
initialised before executing any C code.

  - Zero-initialise NOBITS sections (e.g. the bss section).
  - Relocate BL1 data from ROM to RAM.

Change-Id: I0da81b417b2f0d1f7ef667cc5131b1e47e22571f

  - Check at link-time that bootloader images will fit in memory
    at run time and that they won't overlap each other.
  - Remove text and rodata orphan sections.
  - Define new linker symbols to remove the need for platform setup
    code to know the order of sections.
  - Reduce the size of the raw binary images by cutting some sections
    out of the disk image and allocating them at load time, whenever
    possible.
  - Rework alignment constraints on sections.
  - Remove unused linker symbols.
  - Homogenize linker symbols names across all BLs.
  - Add some comments in the linker scripts.

Change-Id: I47a328af0ccc7c8ab47fcc0dc6e7dd26160610b9

Any asynchronous exception caused by the firmware should be handled
in the firmware itself.  For this reason, unmask SError exceptions
(and Debug ones as well) on all boot paths.  Also route external
abort and SError interrupts to EL3, otherwise they will target EL1.

Change-Id: I9c191d2d0dcfef85f265641c8460dfbb4d112092

blx_plat_arch_setup() should only perform platform-specific
architectural setup, e.g. enabling the MMU.  This patch moves
generic architectural setup code out of blx_plat_arch_setup().

Change-Id: I4ccf56b8c4a2fa84909817779a2d97a14aaafab6