GitLab

Currently, the BUILD_STRING is just 7-digits git hash.  It is true
we can identify which version is running, but we can not get a quick
idea about how new or old it is.

The command "git describe" provides us a bit more useful information
in the format of:
  (tag-name)-(number of commits on top the tag)-g(7 digits hash)

I added some options:
  --always
    Make "git describe" work without any tag in case the upstream
    ATF is cloned, but all the tags are locally dropped.

  --tags
    Use any tag instead of only annotated tags.  In ATF, only some
    tags are annotated, actually the last annotated tag is "v0.2",
    whereas we are on "v1.3" tag now.  This option is needed to get
    something like v1.3-233-gbcc2bf09 instead of v0.2-1713-gbcc2bf09.

  --dirty
    The mark "-dirty" is appended if the source tree is locally
    modified.

With this commit, the welcome string

  NOTICE:  BL1: v1.3(debug):bcc2bf09

will become like follows:

  NOTICE:  BL1: v1.3(debug):v1.3-233-gbcc2bf09

-dirty

While we are here, let's add "2> /dev/null" as well to silently
ignore any error message from git.  We should not assume that users
always work in a git repository; the ATF might be released in a
tarball form instead of a git repository.  In such a case, the git
command will fail, then the ugly message "fatal: Not a git ..." will
be displayed during the build:

$ make CROSS_COMPILE=aarch64-linux-gnu-
fatal: Not a git repository (or any of the parent directories): .git
Building fvp
  CC      drivers/io/io_semihosting.c
  CC      lib/semihosting/semihosting.c
     ...
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

The errata reporting policy is as follows:

  - If an errata workaround is enabled:

    - If it applies (i.e. the CPU is affected by the errata), an INFO
      message is printed, confirming that the errata workaround has been
      applied.

    - If it does not apply, a VERBOSE message is printed, confirming
      that the errata workaround has been skipped.

  - If an errata workaround is not enabled, but would have applied had
    it been, a WARN message is printed, alerting that errata workaround
    is missing.

The CPU errata messages are printed by both BL1 (primary CPU only) and
runtime firmware on debug builds, once for each CPU/errata combination.

Relevant output from Juno r1 console when ARM Trusted Firmware is built
with PLAT=juno LOG_LEVEL=50 DEBUG=1:

  VERBOSE: BL1: cortex_a57: errata workaround for 806969 was not applied
  VERBOSE: BL1: cortex_a57: errata workaround for 813420 was not applied
  INFO:    BL1: cortex_a57: errata workaround for disable_ldnp_overread was applied
  WARNING: BL1: cortex_a57: errata workaround for 826974 was missing!
  WARNING: BL1: cortex_a57: errata workaround for 826977 was missing!
  WARNING: BL1: cortex_a57: errata workaround for 828024 was missing!
  WARNING: BL1: cortex_a57: errata workaround for 829520 was missing!
  WARNING: BL1: cortex_a57: errata workaround for 833471 was missing!
  ...
  VERBOSE: BL31: cortex_a57: errata workaround for 806969 was not applied
  VERBOSE: BL31: cortex_a57: errata workaround for 813420 was not applied
  INFO:    BL31: cortex_a57: errata workaround for disable_ldnp_overread was applied
  WARNING: BL31: cortex_a57: errata workaround for 826974 was missing!
  WARNING: BL31: cortex_a57: errata workaround for 826977 was missing!
  WARNING: BL31: cortex_a57: errata workaround for 828024 was missing!
  WARNING: BL31: cortex_a57: errata workaround for 829520 was missing!
  WARNING: BL31: cortex_a57: errata workaround for 833471 was missing!
  ...
  VERBOSE: BL31: cortex_a53: errata workaround for 826319 was not applied
  INFO:    BL31: cortex_a53: errata workaround for disable_non_temporal_hint was applied

Also update documentation.

Change-Id: Iccf059d3348adb876ca121cdf5207bdbbacf2aba
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

Disable the automatic substitution of functions with builtins. The
existing -ffreestanding option should already do this but explicitly
adding -fno-builtin reduces the risk of compiler variation. With this
option, GCC is not supposed to be able to make assumptions on what the
function does, which could otherwise lead to security-sensitive code
removal.

This can lead to potentially less efficient code but improves
predictability of what code is actually compiled into the binary.

Change-Id: I06ad151c61318bd1b00d84976f051d2d94314acc
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>

The current fiptool packs all the images without any padding between
them.  So, the offset to each image has no alignment.  This is not
efficient, for example, when the FIP is read from a block-oriented
device.

For example, (e)MMC is accessed by block-addressing.  The block size
is 512 byte.  So, the best case is each image is aligned by 512 byte
since the DMA engine can transfer the whole of the image to its load
address directly.  The worst case is the offset does not have even
DMA-capable alignment (this is where we stand now).  In this case,
we need to transfer every block to a bounce buffer, then do memcpy()
from the bounce buffer to our final destination.  At least, this
should work with the abstraction by the block I/O layer, but the
CPU-intervention for the whole data transfer makes it really slow.

This commit adds a new option --align to the fiptool.  This option,
if given, requests the tool to align each component in the FIP file
by the specified byte.  Also, add a new Make option FIP_ALIGN for
easier access to this feature; users can give something like
FIP_ALIGN=512 from the command line, or add "FIP_ALIGN := 512" to
their platform.mk file.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

When generating the list of files to check by checkpatch.pl, the list
generated by `git ls-files` is filtered by a regular expression with
grep. Due to a malformed regex, the dot of `.md` was considered a
wildcard instead of a dot. This patch fixes this so that it matches
only dots, thus allowing the two following files to be checked:

* tools/cert_create/include/cmd_opt.h
* tools/cert_create/src/cmd_opt.c

Also extended the list of library directories to check by checkpatch
to exclude any folder starting with libfdt.

Change-Id: Ie7bf18efe4df29e364e5d67ba1118515304ed9a4
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Using AS for pre-processing looks a bit weird, and some assembly
specific options are given for nothing.  Rather, use CPP.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

The -c flag should not be included in the global variable TF_CFLAGS;
it should be specified in the build rule only when its target is a
*.o file.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

This patch enables TRUSTED_BOARD_BOOT (Authentication and FWU)
support, for AArch64, when LOAD_IMAGE_V2 is enabled.

This patch also enables LOAD_IMAGE_V2 for ARM platforms.

Change-Id: I294a2eebce7a30b6784c80c9d4ac7752808ee3ad
Signed-off-by: Yatharth Kochar <yatharth.kochar@arm.com>

When build variables are assigned or processed en masse, they'd appear
neater in alphabetical order.

Static initializations are moved to a separate file,
make_helpers/defaults.mk, which in itself is sorted alphabetically.

No functional changes.

Change-Id: I966010042b33de6b67592fb9ffcef8fc44d7d128
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

Checkpatch is a script developed to verify the style of Linux kernel
patches. As Kernel developers use emails to send patches for review,
checkpatch is prepared for that specific format. This change adapts
the Makefile to use said format.

As a result, indentation in the commit message has been removed, thus
fixing the warnings about Signed-off-by lines being preceded by
whitespace.

Fixes ARM-software/tf-issues#432

Change-Id: I00cb86365fe15f7e2c3a99a306c8eb51cf02fe86
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Change-Id: I05991543d28e70b67be600b714990af6a8d7ba29

In order to quantify the overall time spent in the PSCI software
implementation, an initial collection of PMF instrumentation points
has been added.

Instrumentation has been added to the following code paths:

- Entry to PSCI SMC handler.  The timestamp is captured as early
  as possible during the runtime exception and stored in memory
  before entering the PSCI SMC handler.

- Exit from PSCI SMC handler.  The timestamp is captured after
  normal return from the PSCI SMC handler or if a low power state
  was requested it is captured in the bl31 warm boot path before
  return to normal world.

- Entry to low power state.  The timestamp is captured before entry
  to a low power state which implies either standby or power down.
  As these power states are mutually exclusive, only one timestamp
  is defined to describe both.  It is possible to differentiate between
  the two power states using the PSCI STAT interface.

- Exit from low power state.  The timestamp is captured after a standby
  or power up operation has completed.

To calculate the number of cycles spent running code in Trusted Firmware
one can perform the following calculation:

(exit_psci - enter_psci) - (exit_low_pwr - enter_low_pwr).

The resulting number of cycles can be converted to time given the
frequency of the counter.

Change-Id: Ie3b8f3d16409b6703747093b3a2d5c7429ad0166
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>

Insert a cosmetic space before "(FIP)".
Signed-off-by: Andreas Färber <afaerber@suse.de>

This patch adds ARM platform changes in BL2 for AArch32 state.
It instantiates a descriptor array for ARM platforms describing
image and entrypoint information for `SCP_BL2`, `BL32` and `BL33`.
It also enables building of BL2 for ARCH=aarch32.

Change-Id: I60dc7a284311eceba401fc789311c50ac746c51e

This patch adds ARM platform changes in BL1 for AArch32 state.
It also enables building of BL1 for ARCH=aarch32.

Change-Id: I079be81a93d027f37b0f7d8bb474b1252bb4cf48

This patch adds common changes to support AArch32 state in
BL1 and BL2. Following are the changes:

* Added functions for disabling MMU from Secure state.
* Added AArch32 specific SMC function.
* Added semihosting support.
* Added reporting of unhandled exceptions.
* Added uniprocessor stack support.
* Added `el3_entrypoint_common` macro that can be
  shared by BL1 and BL32 (SP_MIN) BL stages. The
  `el3_entrypoint_common` is similar to the AArch64
  counterpart with the main difference in the assembly
  instructions and the registers that are relevant to
  AArch32 execution state.
* Enabled `LOAD_IMAGE_V2` flag in Makefile for
  `ARCH=aarch32` and added check to make sure that
  platform has not overridden to disable it.

Change-Id: I33c6d8dfefb2e5d142fdfd06a0f4a7332962e1a3

This patch adds capability to load BL images based on image
descriptors instead of hard coded way of loading BL images.
This framework is designed such that it can be readily adapted
by any BL stage that needs to load images.

In order to provide the above capability the following new
platform functions are introduced:

  bl_load_info_t *plat_get_bl_image_load_info(void);
    This function returns pointer to the list of images that the
    platform has populated to load.

  bl_params_t *plat_get_next_bl_params(void);
    This function returns a pointer to the shared memory that the
    platform has kept aside to pass trusted firmware related
    information that next BL image needs.

  void plat_flush_next_bl_params(void);
    This function flushes to main memory all the params that
    are passed to next image.

  int bl2_plat_handle_post_image_load(unsigned int image_id)
    This function can be used by the platforms to update/use
    image information for given `image_id`.

`desc_image_load.c` contains utility functions which can be used
by the platforms to generate, load and executable, image list
based on the registered image descriptors.

This patch also adds new version of `load_image/load_auth_image`
functions in-order to achieve the above capability.

Following are the changes for the new version as compared to old:
  - Refactor the signature and only keep image_id and image_info_t
    arguments. Removed image_base argument as it is already passed
    through image_info_t. Given that the BL image base addresses and
    limit/size are already provided by the platforms, the meminfo_t
    and entry_point_info arguments are not needed to provide/reserve
    the extent of free memory for the given BL image.

  - Added check for the image size against the defined max size.
    This is needed because the image size could come from an
    unauthenticated source (e.g. the FIP header).
    To make this check, new member is added to the image_info_t
    struct for identifying the image maximum size.

New flag `LOAD_IMAGE_V2` is added in the Makefile.
Default value is 0.

NOTE: `TRUSTED_BOARD_BOOT` is currently not supported when
      `LOAD_IMAGE_V2` is enabled.

Change-Id: Ia7b643f4817a170d5a2fbf479b9bc12e63112e79

More headers will be needed soon so better to move these to their own
directory to avoid cluttering include/lib.

Change-Id: I6a72dc5b602d6f51954cf60aadd1beb52a268670

This patch enables the AArch32 build including SP_MIN in the
top level Makefile. The build flag `ARCH` now can specify either
`aarch64`(default) or `aarch32`. Currently only FVP AEM model is
supported for AArch32 build. Another new build flag `AARCH32_SP`
is introduced to specify the AArch32 secure payload to be built.

Change-Id: Ie1198cb9e52d7da1b79b93243338fc3868b08faa

This patch adds the essential AArch32 architecture helpers
arch.h and arch_helpers.h and modifies `_types.h` to add AArch32
support.

A new build option `ARCH` is defined in the top level makefile to
enable the component makefiles to choose the right files based on the
Architecture it is being build for. Depending on this flag, either
`AARCH32` or `AARCH64` flag is defined by the Makefile. The default
value of `ARCH` flag is `aarch64`. The AArch32 build support will be
added in a later patch.

Change-Id: I405e5fac02db828a55cd25989b572b64cb005241

fiptool provides a more consistent and intuitive interface compared to
the fip_create program.  It serves as a better base to build on more
features in the future.

fiptool supports various subcommands.  Below are the currently
supported subcommands:

1) info   - List the images contained in a FIP file.
2) create - Create a new FIP file with the given images.
3) update - Update an existing FIP with the given images.
4) unpack - Extract a selected set or all the images from a FIP file.
5) remove - Remove images from a FIP file.  This is a new command that
   was not present in fip_create.

To create a new FIP file, replace "fip_create" with "fiptool create".

To update a FIP file, replace "fip_create" with "fiptool update".

To dump the contents of a FIP file, replace "fip_create --dump" with
"fiptool info".

A compatibility script that emulates the basic functionality of
fip_create is provided.  Existing scripts might or might not work with
the compatibility script.  Users are strongly encouraged to migrate to
fiptool.

Fixes ARM-Software/tf-issues#87
Fixes ARM-Software/tf-issues#108
Fixes ARM-Software/tf-issues#361

Change-Id: I7ee4da7ac60179cc83cf46af890fd8bc61a53330

This patch moves the PSCI services and BL31 frameworks like context
management and per-cpu data into new library components `PSCI` and
`el3_runtime` respectively. This enables PSCI to be built independently from
BL31. A new `psci_lib.mk` makefile is introduced which adds the relevant
PSCI library sources and gets included by `bl31.mk`. Other changes which
are done as part of this patch are:

* The runtime services framework is now moved to the `common/` folder to
  enable reuse.
* The `asm_macros.S` and `assert_macros.S` helpers are moved to architecture
  specific folder.
* The `plat_psci_common.c` is moved from the `plat/common/aarch64/` folder
  to `plat/common` folder. The original file location now has a stub which
  just includes the file from new location to maintain platform compatibility.

Most of the changes wouldn't affect platform builds as they just involve
changes to the generic bl1.mk and bl31.mk makefiles.

NOTE: THE `plat_psci_common.c` FILE HAS MOVED LOCATION AND THE STUB FILE AT
THE ORIGINAL LOCATION IS NOW DEPRECATED. PLATFORMS SHOULD MODIFY THEIR
MAKEFILES TO INCLUDE THE FILE FROM THE NEW LOCATION.

Change-Id: I6bd87d5b59424995c6a65ef8076d4fda91ad5e86

At the moment, all BL images share a similar memory layout: they start
with their code section, followed by their read-only data section.
The two sections are contiguous in memory. Therefore, the end of the
code section and the beginning of the read-only data one might share
a memory page. This forces both to be mapped with the same memory
attributes. As the code needs to be executable, this means that the
read-only data stored on the same memory page as the code are
executable as well. This could potentially be exploited as part of
a security attack.

This patch introduces a new build flag called
SEPARATE_CODE_AND_RODATA, which isolates the code and read-only data
on separate memory pages. This in turn allows independent control of
the access permissions for the code and read-only data.

This has an impact on memory footprint, as padding bytes need to be
introduced between the code and read-only data to ensure the
segragation of the two. To limit the memory cost, the memory layout
of the read-only section has been changed in this case.

 - When SEPARATE_CODE_AND_RODATA=0, the layout is unchanged, i.e.
   the read-only section still looks like this (padding omitted):

   |        ...        |
   +-------------------+
   | Exception vectors |
   +-------------------+
   |  Read-only data   |
   +-------------------+
   |       Code        |
   +-------------------+ BLx_BASE

   In this case, the linker script provides the limits of the whole
   read-only section.

 - When SEPARATE_CODE_AND_RODATA=1, the exception vectors and
   read-only data are swapped, such that the code and exception
   vectors are contiguous, followed by the read-only data. This
   gives the following new layout (padding omitted):

   |        ...        |
   +-------------------+
   |  Read-only data   |
   +-------------------+
   | Exception vectors |
   +-------------------+
   |       Code        |
   +-------------------+ BLx_BASE

   In this case, the linker script now exports 2 sets of addresses
   instead: the limits of the code and the limits of the read-only
   data. Refer to the Firmware Design guide for more details. This
   provides platform code with a finer-grained view of the image
   layout and allows it to map these 2 regions with the appropriate
   access permissions.

Note that SEPARATE_CODE_AND_RODATA applies to all BL images.

Change-Id: I936cf80164f6b66b6ad52b8edacadc532c935a49

This patch adds following optional PSCI STAT functions:

- PSCI_STAT_RESIDENCY: This call returns the amount of time spent
  in power_state in microseconds, by the node represented by the
  `target_cpu` and the highest level of `power_state`.

- PSCI_STAT_COUNT: This call returns the number of times a
  `power_state` has been used by the node represented by the
  `target_cpu` and the highest power level of `power_state`.

These APIs provides residency statistics for power states that has
been used by the platform. They are implemented according to v1.0
of the PSCI specification.

By default this optional feature is disabled in the PSCI
implementation. To enable it, set the boolean flag
`ENABLE_PSCI_STAT` to 1. This also sets `ENABLE_PMF` to 1.

Change-Id: Ie62e9d37d6d416ccb1813acd7f616d1ddd3e8aff

This patch adds Performance Measurement Framework(PMF) in the
ARM Trusted Firmware. PMF is implemented as a library and the
SMC interface is provided through ARM SiP service.

The PMF provides capturing, storing, dumping and retrieving the
time-stamps, by enabling the development of services by different
providers, that can be easily integrated into ARM Trusted Firmware.
The PMF capture and retrieval APIs can also do appropriate cache
maintenance operations to the timestamp memory when the caller
indicates so.

`pmf_main.c` consists of core functions that implement service
registration, initialization, storing, dumping and retrieving
the time-stamp.
`pmf_smc.c` consists SMC handling for registered PMF services.
`pmf.h` consists of the macros that can be used by the PMF service
providers to register service and declare time-stamp functions.
`pmf_helpers.h` consists of internal macros that are used by `pmf.h`

By default this feature is disabled in the ARM trusted firmware.
To enable it set the boolean flag `ENABLE_PMF` to 1.

NOTE: The caller is responsible for specifying the appropriate cache
maintenance flags and for acquiring/releasing appropriate locks
before/after capturing/retrieving the time-stamps.

Change-Id: Ib45219ac07c2a81b9726ef6bd9c190cc55e81854

At the moment, the top Makefile specifies the options to pass to the
checkpatch script in order to check the coding style. The checkpatch
script also supports reading its options from a configuration file
rather than from the command line.

This patch makes use of this feature and moves the checkpatch options
out of the Makefile. This simplifies the Makefile and makes things
clearer.

This patch also adds some more checkpatch options:
  --showfile
  --ignore FILE_PATH_CHANGES
  --ignore AVOID_EXTERNS
  --ignore NEW_TYPEDEFS
  --ignore VOLATILE
The rationale behind each of these options has been documented
in the configuration file.

Change-Id: I423e1abe5670c0f57046cbf705f89a8463898676

Exclude documentation files from the `make checkcodebase` target
(these files were already excluded from checkpatch).

Also exclude libfdt files to prepare for import of this library.

Change-Id: Iee597ed66494de2b11cf84096f771f1f04472d5b

* Move stdlib header files from include/stdlib to include/lib/stdlib for
  consistency with other library headers.
* Fix checkpatch paths to continue excluding stdlib files.
* Create stdlib.mk to define the stdlib source files and include directories.
* Include stdlib.mk from the top level Makefile.
* Update stdlib header path in the fip_create Makefile.
* Update porting-guide.md with the new paths.

Change-Id: Ia92c2dc572e9efb54a783e306b5ceb2ce24d27fa

The system registers that are saved and restored in CPU context include
AArch32 systems registers like SPSR_ABT, SPSR_UND, SPSR_IRQ, SPSR_FIQ,
DACR32_EL2, IFSR32_EL2 and FPEXC32_EL2. Accessing these registers on an
AArch64-only (i.e. on hardware that does not implement AArch32, or at
least not at EL1 and higher ELs) platform leads to an exception. This patch
introduces the build option `CTX_INCLUDE_AARCH32_REGS` to specify whether to
include these AArch32 systems registers in the cpu context or not. By default
this build option is set to 1 to ensure compatibility. AArch64-only platforms
must set it to 0. A runtime check is added in BL1 and BL31 cold boot path to
verify this.

Fixes ARM-software/tf-issues#386

Change-Id: I720cdbd7ed7f7d8516635a2ec80d025f478b95ee

The user can provide additional CFLAGS to use when building TF.
However, these custom CFLAGS are currently prepended to the
standard CFLAGS that are hardcoded in the TF build system. This
is an issue because when providing conflicting compiler flags
(e.g. different optimisations levels like -O1 and -O0), the last
one on the command line usually takes precedence. This means that
the user flags get overriden.

To address this problem, this patch separates the TF CFLAGS from
the user CFLAGS. The former are now stored in the TF_CFLAGS make
variable, whereas the CFLAGS make variable is untouched and reserved
for the user. The order of the 2 sets of flags is enforced when
invoking the compiler.

Fixes ARM-Software/tf-issues#350

Change-Id: Ib189f44555b885f1dffbec6015092f381600e560

All markdown (.md) files in the root directory of the repository and
all the files inside the 'docs' directory have been removed from
ROOT_DIRS_TO_CHECK in the Makefile in order not to perform the coding
style check on them.

Change-Id: Iac397b44f95cbcdb9a52cc20bf69998c394ac00a

Removed an extra parentheses that produced an invalid list of files
and directories to check by checkpatch.pl.

Change-Id: Iefe2c1f8be6e7b7b58f6ffe3e16fe6336b9a8689

To avoid confusion the build option BL33_BASE has been renamed to
PRELOADED_BL33_BASE, which is more descriptive of what it does and
doesn't get mistaken by similar names like BL32_BASE that work in a
completely different way.

NOTE: PLATFORMS USING BUILD OPTION `BL33_BASE` MUST CHANGE TO THE NEW
BUILD OPTION `PRELOADED_BL33_BASE`.

Change-Id: I658925ebe95406edf0325f15aa1752e1782aa45b

Previously, when building TF without SPD support, BL2 tried to load a
BL32 image from the FIP and fails to find one, which resulted on
warning messages on the console. Even if there is a BL32 image in the
FIP it shouldn't be loaded because there is no way to transfer
control to the Secure Payload without SPD support.

The Makefile has been modified to pass a define of the form
SPD_${SPD} to the source code the same way it's done for PLAT. The
define SPD_none is then used to undefine BL32_BASE when BL32 is not
used to prevent BL2 from trying to load a BL32 image and failing,
thus removing the warning messages mentioned above.

Fixes ARM-software/tf-issues#287

Change-Id: Ifeb6f1c26935efb76afd353fea88e87ba09e9658

In some build environments executable programs have a specific file
extension.  The value of BIN_EXT is appended to the relevant tool file
names to allow for this.
The value of BIN_EXT is set, where appropriate, by the build environment
specific make helper (to .exe for Windows build environments).

.gitignore is updated to hide the new (.exe) files.

Change-Id: Icc32f64b750e425265075ad4e0dea18129640b86

Replace some "recursively expanded" make variables with "simply
expanded" variables (i.e. replace = with :=). This has no functional
impact but is more consistent and theoretically more efficient.

Change-Id: Iaf33d7c8ad48464ae0d39923515d1e7f230c95c1

Add make helper files to select the appropriate settings for the build
environment. Selection is made in make_helpers/build_env.mk, which
selects other files to include using generic build environment settings.
The Trusted Firmware Makefile and supporting tool Makefiles are updated
to include build_env.mk instead of unix.mk.

NOTE: This change does not fully enable builds in other build
      environments. It facilitates this without compromising the
      existing build environments.

Change-Id: Ic4064ffe6ce158bbd16d7cc9f27dd4655a3580f6

Macros are inserted to replace direct invocations of commands that are
problematic on some build environments. (e.g. Some environments expect
\ in paths instead of /.)
The changes take into account mismatched command mappings across
environments.
The new helper file unix.mk retains existing makefile behaviour on unix
like build environments by providing the following macro definitions:
  SHELL_COPY        cp -f
  SHELL_COPY_TREE   cp -rf
  SHELL_DELETE      rm -f
  SHELL_DELETE_ALL  rm -rf
  MAKE_PREREQ_DIR   mkdir -p  (As make target)
  SHELL_REMOVE_DIR  rm -rf

Change-Id: I1b5ca5e1208e78230b15284c4af00c1c006cffcb

As an initial stage of making Trusted Firmware build environment more
portable, we remove most uses of the $(shell ) function and replace them
with more portable make function based solutions.

Note that the setting of BUILD_STRING still uses $(shell ) since it's
not possible to reimplement this as a make function. Avoiding invocation
of this on incompatible host platforms will be implemented separately.

Change-Id: I768e2f9a265c78814a4adf2edee4cc46cda0f5b8

lib/aarch64/xlat_helpers.c defines helper functions to build
translation descriptors, but no common code or upstream platform
port uses them. As the rest of the xlat_tables code evolves, there
may be conflicts with these helpers, therefore this code should be
removed.

Change-Id: I9f5be99720f929264818af33db8dada785368711