linker_script: move .data section to bl_common.ld.h ...

Move the data section to the common header.

I slightly tweaked some scripts as follows:

[1] bl1.ld.S has ALIGN(16). I added DATA_ALIGN macro, which is 1
    by default, but overridden by bl1.ld.S. Currently, ALIGN(16)
    of the .data section is redundant because commit 412865907699
    ("Fix boot failures on some builds linked with ld.lld.") padded
    out the previous section to work around the issue of LLD version
    <= 10.0. This will be fixed in the future release of LLVM, so
    I am keeping the proper way to align LMA.

[2] bl1.ld.S and bl2_el3.ld.S define __DATA_RAM_{START,END}__ instead
    of __DATA_{START,END}__. I put them out of the .data section.

[3] SORT_BY_ALIGNMENT() is missing tsp.ld.S, sp_min.ld.S, and
    mediatek/mt6795/bl31.ld.S. This commit adds SORT_BY_ALIGNMENT()
    for all images, so the symbol order in those three will change,
    but I do not think it is a big deal.

Change-Id: I215bb23c319f045cd88e6f4e8ee2518c67f03692
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

linker_script: move stacks section to bl_common.ld.h ...

The stacks section is the same for all BL linker scripts.

Move it to the common header file.

Change-Id: Ibd253488667ab4f69702d56ff9e9929376704f6c
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

linker_script: move bss section to bl_common.ld.h ...

Move the bss section to the common header. This adds BAKERY_LOCK_NORMAL
and PMF_TIMESTAMP, which previously existed only in BL31. This is not
a big deal because unused data should not be compiled in the first
place. I believe this should be controlled by BL*_SOURCES in Makefiles,
not by linker scripts.

I investigated BL1, BL2, BL2U, BL31 for plat=fvp, and BL2-AT-EL3,
BL31, BL31 for plat=uniphier. I did not see any more  unexpected
code addition.

The bss section has bigger alignment. I added BSS_ALIGN for this.

Currently, SORT_BY_ALIGNMENT() is missing in sp_min.ld.S, and with this
change, the BSS symbols in SP_MIN will be sorted by the alignment.
This is not a big deal (or, even better in terms of the image size).

Change-Id: I680ee61f84067a559bac0757f9d03e73119beb33
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

linker_script: replace common read-only data with RODATA_COMMON ...

The common section data are repeated in many linker scripts (often
twice in each script to support SEPARATE_CODE_AND_RODATA). When you
add a new read-only data section, you end up with touching lots of
places.

After this commit, you will only need to touch bl_common.ld.h when
you add a new section to RODATA_COMMON.

Replace a series of RO section with RODATA_COMMON, which contains
6 sections, some of which did not exist before.

This is not a big deal because unneeded data should not be compiled
in the first place. I believe this should be controlled by BL*_SOURCES
in Makefiles, not by linker scripts.

When I was working on this commit, the BL1 image size increased
due to the fconf_populator. Commit c452ba159c14 ("fconf: exclude
fconf_dyn_cfg_getter.c from BL1_SOURCES") fixed this issue.

I investigated BL1, BL2, BL2U, BL31 for plat=fvp, and BL2-AT-EL3,
BL31, BL31 for plat=uniphier. I did not see any more  unexpected
code addition.

Change-Id: I5d14d60dbe3c821765bce3ae538968ef266f1460
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Factor xlat_table sections in linker scripts out into a header file ...

TF-A has so many linker scripts, at least one linker script for each BL
image, and some platforms have their own ones. They duplicate quite
similar code (and comments).

When we add some changes to linker scripts, we end up with touching
so many files. This is not nice in the maintainability perspective.

When you look at Linux kernel, the common code is macrofied in
include/asm-generic/vmlinux.lds.h, which is included from each arch
linker script, arch/*/kernel/vmlinux.lds.S

TF-A can follow this approach. Let's factor out the common code into
include/common/bl_common.ld.h

As a start point, this commit factors out the xlat_table section.

Change-Id: Ifa369e9b48e8e12702535d721cc2a16d12397895
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Reduce space lost to object alignment ...

Currently, sections within .text/.rodata/.data/.bss are emitted in the
order they are seen by the linker. This leads to wasted space, when a
section with a larger alignment follows one with a smaller alignment.
We can avoid this wasted space by sorting the sections.

To take full advantage of this, we must disable generation of common
symbols, so "common" data can be sorted along with the rest of .bss.

An example of the improvement, from `make DEBUG=1 PLAT=sun50i_a64 bl31`:
  .text   => no change
  .rodata => 16 bytes saved
  .data   => 11 bytes saved
  .bss    => 576 bytes saved

As a side effect, the addition of `-fno-common` in TF_CFLAGS makes it
easier to spot bugs in header files.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Change-Id: I073630a9b0b84e7302a7a500d4bb4b547be01d51

Sanitise includes across codebase ...

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: e0ea0928d5b7 ("Fix gpio includes of mt8173 platform
to avoid collision."). More recently, this patch has had similar
problems: 46f9b2c3a282 ("drivers: add tzc380 support").

This problem was introduced in commit 4ecca33988b9 ("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>

Add .extab and .exidx sections ...

These sections are required by clang when the code is compiled for
aarch32. These sections are related to the unwind of the stack in
exceptions, but in the way that clang defines and uses them, the
garbage collector cannot get rid of them.

Change-Id: I085efc0cf77eae961d522472f72c4b5bad2237ab
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>

Use ALIGN instead of NEXT in linker scripts ...

Clang linker doesn't support NEXT. As we are not using the MEMORY command
to define discontinuous memory for the output file in any of the linker
scripts, ALIGN and NEXT are equivalent.

Change-Id: I867ffb9c9a76d4e81c9ca7998280b2edf10efea0
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>

Add comments about mismatched TCR_ELx and xlat tables ...

When the MMU is enabled and the translation tables are mapped, data
read/writes to the translation tables are made using the attributes
specified in the translation tables themselves. However, the MMU
performs table walks with the attributes specified in TCR_ELx. They are
completely independent, so special care has to be taken to make sure
that they are the same.

This has to be done manually because it is not practical to have a test
in the code. Such a test would need to know the virtual memory region
that contains the translation tables and check that for all of the
tables the attributes match the ones in TCR_ELx. As the tables may not
even be mapped at all, this isn't a test that can be made generic.

The flags used by enable_mmu_xxx() have been moved to the same header
where the functions are.

Also, some comments in the linker scripts related to the translation
tables have been fixed.

Change-Id: I1754768bffdae75f53561b1c4a5baf043b45a304
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Replace magic numbers in linkerscripts by PAGE_SIZE ...

When defining different sections in linker scripts it is needed to align
them to multiples of the page size. In most linker scripts this is done
by aligning to the hardcoded value 4096 instead of PAGE_SIZE.

This may be confusing when taking a look at all the codebase, as 4096
is used in some parts that aren't meant to be a multiple of the page
size.

Change-Id: I36c6f461c7782437a58d13d37ec8b822a1663ec1
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Use SPDX license identifiers ...

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>

Add support for GCC stack protection ...

Introduce new build option ENABLE_STACK_PROTECTOR. It enables
compilation of all BL images with one of the GCC -fstack-protector-*
options.

A new platform function plat_get_stack_protector_canary() is introduced.
It returns a value that is used to initialize the canary for stack
corruption detection. Returning a random value will prevent an attacker
from predicting the value and greatly increase the effectiveness of the
protection.

A message is printed at the ERROR level when a stack corruption is
detected.

To be effective, the global data must be stored at an address
lower than the base of the stacks. Failure to do so would allow an
attacker to overwrite the canary as part of an attack which would void
the protection.

FVP implementation of plat_get_stack_protector_canary is weak as
there is no real source of entropy on the FVP. It therefore relies on a
timer's value, which could be predictable.

Change-Id: Icaaee96392733b721fa7c86a81d03660d3c1bc06
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>

Introduce unified API to zero memory ...

Introduce zeromem_dczva function on AArch64 that can handle unaligned
addresses and make use of DC ZVA instruction to zero a whole block at a
time. This zeroing takes place directly in the cache to speed it up
without doing external memory access.

Remove the zeromem16 function on AArch64 and replace it with an alias to
zeromem. This zeromem16 function is now deprecated.

Remove the 16-bytes alignment constraint on __BSS_START__ in
firmware-design.md as it is now not mandatory anymore (it used to comply
with zeromem16 requirements).

Change the 16-bytes alignment constraints in SP min's linker script to a
8-bytes alignment constraint as the AArch32 zeromem implementation is now
more efficient on 8-bytes aligned addresses.

Introduce zero_normalmem and zeromem helpers in platform agnostic header
that are implemented this way:
* AArch32:
	* zero_normalmem: zero using usual data access
	* zeromem: alias for zero_normalmem
* AArch64:
	* zero_normalmem: zero normal memory  using DC ZVA instruction
	                  (needs MMU enabled)
	* zeromem: zero using usual data access

Usage guidelines: in most cases, zero_normalmem should be preferred.

There are 2 scenarios where zeromem (or memset) must be used instead:
* Code that must run with MMU disabled (which means all memory is
  considered device memory for data accesses).
* Code that fills device memory with null bytes.

Optionally, the following rule can be applied if performance is
important:
* Code zeroing small areas (few bytes) that are not secrets should use
  memset to take advantage of compiler optimizations.

  Note: Code zeroing security-related critical information should use
  zero_normalmem/zeromem instead of memset to avoid removal by
  compilers' optimizations in some cases or misbehaving versions of GCC.

Fixes ARM-software/tf-issues#408

Change-Id: Iafd9663fc1070413c3e1904e54091cf60effaa82
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>

Introduce SEPARATE_CODE_AND_RODATA build flag ...

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

FWU: Add Generic BL2U FWU image support in BL2 ...

The Firmware Update (FWU) feature needs support for an optional
secure world image, BL2U, to allow additional secure world
initialization required by FWU, for example DDR initialization.

This patch adds generic framework support to create BL2U.

NOTE: A platform makefile must supply additional `BL2U_SOURCES`
      to build the bl2u target. A subsequent patch adds bl2u
      support for ARM platforms.

Change-Id: If2ce036199bb40b39b7f91a9332106bcd4e25413