GitLab

Core spm_mm code expects the translation tables are located in the
inner & outer WBWA & shareable memory.
REGISTER_XLAT_CONTEXT2 macro is used to specify the translation
table section in spm_mm.

In the commit 363830df

 (xlat_tables_v2: merge
REGISTER_XLAT_CONTEXT_{FULL_SPEC,RO_BASE_TABLE}), REGISTER_XLAT_CONTEXT2
macro explicitly specifies the base xlat table goes into .bss by default.
This change affects the existing SynQuacer spm_mm implementation.
plat/socionext/synquacer/include/plat.ld.S linker script intends to
locate ".bss.sp_base_xlat_table" into "sp_xlat_table" section,
but this implementation is no longer available.

This patch adds the base table section name parameter for
REGISTER_XLAT_CONTEXT2 so that platform can specify the
inner & outer WBWA & shareable memory for spm_mm base xlat table.
If PLAT_SP_IMAGE_BASE_XLAT_SECTION_NAME is not defined, base xlat table
goes into .bss by default, the result is same as before.

Change-Id: Ie0e1a235e5bd4288dc376f582d6c44c5df6d31b2
Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>

Present framework restricts platform to pass desired shareability attribute
for normal memory region mapped in MMU. it defaults to inner shareability.

There are platforms where memories (like SRAM) are not placed at snoopable
region in advaned interconnect like CCN/CMN hence snoopable transaction is
not possible to these memory. Though These memories could be mapped in MMU
as MT_NON_CACHEABLE, data caches benefits won't be available.

If these memories are mapped as cacheable with non-shareable attribute,
when only one core is running like at boot time, MMU data cached could be
used for faster execution. Hence adding support to pass the shareability
attribute for memory regions.
Signed-off-by: Pramod Kumar <pramod.kumar@broadcom.com>
Change-Id: I678cb50120a28dae4aa9d1896e8faf1dd5cf1754

If PLAT_RO_XLAT_TABLES is defined, the base xlat table goes to the
.rodata section instead of .bss section.

This causes a warning like:

/tmp/ccswitLr.s: Assembler messages:
/tmp/ccswitLr.s:297: Warning: setting incorrect section attributes for .rodata

It is practically no problem, but I want to keep the build log clean.

Put the base table into the "base_xlat_table" section to suppress the
assembler warnings.

The linker script determines its final destination; rodata section if
PLAT_RO_XLAT_TABLES=1, or bss section otherwise. So, the result is the
same.

Change-Id: Ic85d1d2dddd9b5339289fc2378cbcb21dd7db02e
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

xlat_tables_v2_helpers.h defines two quite similar macros,
REGISTER_XLAT_CONTEXT_FULL_SPEC and REGISTER_XLAT_CONTEXT_RO_BASE_TABLE.

Only the difference is the section of _ctx_name##_base_xlat_table.

Parameterize it and unify these two macros.

The base xlat table goes into the .bss section by default.
If PLAT_RO_XLAT_TABLES is defined, it goes into the .rodata section.

Change-Id: I8b02f4da98f0c272e348a200cebd89f479099c55
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

This patch introduces a build flag which allows the xlat tables
to be mapped in a read-only region within BL31 memory. It makes it
much harder for someone who has acquired the ability to write to
arbitrary secure memory addresses to gain control of the
translation tables.

The memory attributes of the descriptors describing the tables
themselves are changed to read-only secure data. This change
happens at the end of BL31 runtime setup. Until this point, the
tables have read-write permissions. This gives a window of
opportunity for changes to be made to the tables with the MMU on
(e.g. reclaiming init code). No changes can be made to the tables
with the MMU turned on from this point onwards. This change is also
enabled for sp_min and tspd.

To make all this possible, the base table was moved to .rodata. The
penalty we pay is that now .rodata must be aligned to the size of
the base table (512B alignment). Still, this is better than putting
the base table with the higher level tables in the xlat_table
section, as that would cost us a full 4KB page.

Changing the tables from read-write to read-only cannot be done with
the MMU on, as the break-before-make sequence would invalidate the
descriptor which resolves the level 3 page table where that very
descriptor is located. This would make the translation required for
writing the changes impossible, generating an MMU fault.

The caches are also flushed.
Signed-off-by: Petre-Ionut Tudor <petre-ionut.tudor@arm.com>
Change-Id: Ibe5de307e6dc94c67d6186139ac3973516430466

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>

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: e0ea0928 ("Fix gpio includes of mt8173 platform
to avoid collision."). More recently, this patch has had similar
problems: 46f9b2c3 ("drivers: add tzc380 support").

This problem was introduced in commit 4ecca339

 ("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>

Change-Id: Ib7c2529b85bb5930d44907edfc8ead13d3b1ef4d
Co-authored-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Provide new APIs to add new regions without specifying the base VA.

- `mmap_add_region_alloc_va` adds a static region to mmap choosing as
  base VA the first possible address after all the currently mapped
  regions. It is aligned to an appropriate boundary in relation to the
  size and base PA of the requested region. No attempt is made to fill
  any unused VA holes.

- `mmap_add_dynamic_region_alloc_va` it adds a region the same way as
  `mmap_add_region_alloc_va` does, but it's dynamic instead of static.

- `mmap_add_alloc_va` takes an array of non const `mmap_region_t`,
  maps them in the same way as `mmap_add_region_alloc_va` and fills
  their `base_va` field. A helper macro has been created to help create
  the array, called `MAP_REGION_ALLOC_VA`.

Change-Id: I5ef3f82ca0dfd0013d2e8034aa22f13ca528ba37
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Change-Id: I83de2ae3e0795e6fec3c1e5b37c441b64b0c9cb6
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

The translation library is useful elsewhere. Even though this repository
doesn't exercise the EL2 support of the library, it is better to have it
here as well to make it easier to maintain.

enable_mmu_secure() and enable_mmu_direct() have been deprecated. The
functions are still present, but they are behind ERROR_DEPRECATED and
they call the new functions enable_mmu_svc_mon() and
enable_mmu_direct_svc_mon().

Change-Id: I13ad10cd048d9cc2d55e0fff9a5133671b67dcba
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Changed the names for consistency with the rest of the library. Introduced
new helpers that manipulate the active translation tables context.

Change-Id: Icaca56b67fcf6a96e88aa3c7e47411162e8e6856
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Fix defects of MISRA C-2012 rules 8.13, 10.1, 10.3, 10.4, 10.8, 11.6,
14.4, 15.7, 17.8, 20.10, 20.12, 21.1 and Directive 4.9.

Change-Id: I7ff61e71733908596dbafe2e99d99b4fce9765bd
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

The Exception Level is now detected at runtime. This means that it is not
needed to hardcode the EL used by each image.

This doesn't result in a substantial increase of the image size because
the initialization functions that aren't used are garbage-collected by
the linker.

In AArch32 the current EL has been changed from EL3 to EL1 because the
the AArch32 PL1&0 translation regime behaves more like the AArch64 EL1&0
translation regime than the EL3 one.

Change-Id: I941404299ebe7666ca17619207c923b49a55cb73
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Instead of having one big file with all the code, it's better to have
a few smaller files that are more manageable:

- xlat_tables_core.c: Code related to the core functionality of the
  library (map and unmap regions, initialize xlat context).
- xlat_tables_context.c: Instantiation of the active image context
  as well as APIs to manipulate it.
- xlat_tables_utils.c: Helper code that isn't part of the core
  functionality (change attributes, debug print messages).

Change-Id: I3ea956fc1afd7473c0bb5e7c6aab3b2e5d88c711
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

At present, the function provided by the translation library to enable
MMU constructs appropriate values for translation library, and programs
them to the right registers. The construction of initial values,
however, is only required once as both the primary and secondaries
program the same values.

Additionally, the MMU-enabling function is written in C, which means
there's an active stack at the time of enabling MMU. On some systems,
like Arm DynamIQ, having active stack while enabling MMU during warm
boot might lead to coherency problems.

This patch addresses both the above problems by:

  - Splitting the MMU-enabling function into two: one that sets up
    values to be programmed into the registers, and another one that
    takes the pre-computed values and writes to the appropriate
    registers. With this, the primary effectively calls both functions
    to have the MMU enabled, but secondaries only need to call the
    latter.

  - Rewriting the function that enables MMU in assembly so that it
    doesn't use stack.

This patch fixes a bunch of MISRA issues on the way.

Change-Id: I0faca97263a970ffe765f0e731a1417e43fbfc45
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

The values defined in this type are used in logical operations, which
goes against MISRA Rule 10.1: "Operands shall not be of an inappropriate
essential type".

Now, `unsigned int` is used instead. This also allows us to move the
dynamic mapping bit from 30 to 31. It was an undefined behaviour in the
past because an enum is signed by default, and bit 31 corresponds to the
sign bit. It is undefined behaviour to modify the sign bit. Now, bit 31
is free to use as it was originally meant to be.

mmap_attr_t is now defined as an `unsigned int` for backwards
compatibility.

Change-Id: I6b31218c14b9c7fdabebe432de7fae6e90a97f34
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Change-Id: I989c1f4aef8e3cb20d5d19e6347575e6449bb60b
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

A new platform define, `PLAT_SP_IMAGE_XLAT_SECTION_NAME`, has been
introduced to select the section where the translation tables used by
the S-EL1/S-EL0 are placed.

This define has been used to move the translation tables to DRAM secured
by TrustZone.

Most of the extra needed space in BL31 when SPM is enabled is due to the
large size of the translation tables. By moving them to this memory
region we can save 44 KiB.

A new argument has been added to REGISTER_XLAT_CONTEXT2() to specify the
region where the translation tables have to be placed by the linker.

Change-Id: Ia81709b4227cb8c92601f0caf258f624c0467719
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

This patch introduces a new API in the translation tables library
(v2), that allows to change the memory attributes of a memory
region. It may be used to change its execution permissions and
data access permissions.

As a prerequisite, the memory must be already mapped. Moreover, it
must be mapped at the finest granularity (currently 4 KB).

Change-Id: I242a8c6f0f3ef2b0a81a61e28706540462faca3c
Co-authored-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Co-authored-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

This patch introduces a new API in the translation tables library
(v2), that allows to query the memory attributes of a memory block
or a memory page.

Change-Id: I45a8b39a53da39e7617cbac4bff5658dc1b20a11
Co-authored-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Co-authored-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

This patch introduces the ability of the xlat tables library to manage
EL0 and EL1 mappings from a higher exception level.

Attributes MT_USER and MT_PRIVILEGED have been added to allow the user
specify the target EL in the translation regime EL1&0.

REGISTER_XLAT_CONTEXT2 macro is introduced to allow creating a
xlat_ctx_t that targets a given translation regime (EL1&0 or EL3).

A new member is added to xlat_ctx_t to represent the translation regime
the xlat_ctx_t manages. The execute_never mask member is removed as it
is computed from existing information.

Change-Id: I95e14abc3371d7a6d6a358cc54c688aa9975c110
Co-authored-by: Douglas Raillard <douglas.raillard@arm.com>
Co-authored-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Co-authored-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Introduce a variant of the TLB invalidation helper function that
allows the targeted translation regime to be specified, rather than
defaulting to the current one.

This new function is useful in the context of EL3 software managing
translation tables for the S-EL1&0 translation regime, as then it
might need to invalidate S-EL1&0 TLB entries rather than EL3 ones.

Define a new enumeration to be able to represent translation regimes in
the xlat tables library.

Change-Id: Ibe4438dbea2d7a6e7470bfb68ff805d8bf6b07e5
Co-authored-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Co-authored-by: Douglas Raillard <douglas.raillard@arm.com>
Co-authored-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

The current implementation of the memory mapping API favours mapping
memory regions using the biggest possible block size in order to
reduce the number of translation tables needed.

In some cases, this behaviour might not be desirable. When translation
tables are edited at run-time, coarse-grain mappings like that might
need splitting into finer-grain tables. This operation has a
performance cost.

The MAP_REGION2() macro allows to specify the granularity of
translation tables used for the initial mapping of a memory region.
This might increase performance for memory regions that are likely to
be edited in the future, at the expense of a potentially increased
memory footprint.

The Translation Tables Library Design Guide has been updated to
explain the use case for this macro. Also added a few intermediate
titles to make the guide easier to digest.

Change-Id: I04de9302e0ee3d326b8877043a9f638766b81b7b
Co-authored-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Co-authored-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Since commit 769d65da ("xlat: Use MAP_REGION macro as compatibility
layer"), building with GCC 4.9 fails.

  CC      plat/arm/board/fvp/fvp_common.c
plat/arm/board/fvp/fvp_common.c:60:2: error: initializer element is not constant
  ARM_MAP_SHARED_RAM,
  ^
plat/arm/board/fvp/fvp_common.c:60:2: error: (near initialization for 'plat_arm_mmap[0]')
make: *** [Makefile:535: build/fvp/release/bl1/fvp_common.o] Error 1

Taking into account that MAP_REGION(_FLAT) is widely used in array
initializers, do not use cast.

Fixes: 769d65da

 ("xlat: Use MAP_REGION macro as compatibility layer")
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Use the MAP_REGION to build the mmap_region_t argument in wrappers like
mmap_add_region(). Evolution of the mmap_region_t might require adding
new members with a non-zero default value. Users of MAP_REGION are
protected against such evolution. This commit also protects users of
mmap_add_region() and mmap_add_dynamic_region() functions against these
evolutions.

Also make the MAP_REGION macro implementation more explicit and make it
a mmap_region_t compound literal to make it useable as a function
parameter on its own and to prevent using it in initialization of
variables of different type.

Change-Id: I7bfc4689f6dd4dd23c895b65f628d8ee991fc161
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>

In a previous patch, the xlat_ctx_t type has been made public.
This patch now makes the *_ctx() APIs public.

Each API now has a *_ctx() variant. Most of them were already implemented
and this patch just makes them public. However, some of them were missing
so this patch introduces them.

Now that all these APIs are public, there's no good reason for splitting
them accross 2 files (xlat_tables_internal.c and xlat_tables_common.c).
Therefore, this patch moves all code into xlat_tables_internal.c and
removes xlat_tables_common.c. It removes it from the library's makefile
as well.

This last change introduces a compatibility break for platform ports
that specifically include the xlat_tables_common.c file instead of
including the library's Makefile. The UniPhier platform makefile has
been updated to now omit this file from the list of source files.

The prototype of mmap_add_region_ctx() has been slightly changed. The
mmap_region_t passed in argument needs to be constant because it gets
called from map_add(), which receives a constant region. The former
implementation of mmap_add() used to cast the const qualifier away,
which is not a good practice.

Also remove init_xlation_table(), which was a sub-function of
init_xlat_tables(). Now there's just init_xlat_tables() (and
init_xlat_tables_ctx()). Both names were too similar, which was
confusing. Besides, now that all the code is in a single file,
it's no longer needed to have 2 functions for that.

Change-Id: I4ed88c68e44561c3902fbebb89cb197279c5293b
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>

At the moment, the translation context type (xlat_ctx_t) is a private
type reserved for the internal usage of the translation table library.
All exported APIs (implemented in xlat_tables_common.c) are wrappers
over the internal implementations that use such a translation context.

These wrappers unconditionally pass the current translation context
representing the memory mappings of the executing BL image. This means
that the caller has no control over which translation context the
library functions act on.

As a first step to make this code more flexible, this patch exports
the 'xlat_ctx_t' type. Note that, although the declaration of this type
is now public, its definition stays private. A macro is introduced to
statically allocate and initialize such a translation context.

The library now internally uses this macro to allocate the default
translation context for the running BL image.

Change-Id: Icece1cde4813fac19452c782b682c758142b1489
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@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>

- Fix some comments.
- Remove duplicated definition.
- Make xlat_arch_get_max_supported_pa() private in aarch64.

Change-Id: I629237209cfb2ce7b0c4bd539d63dd81d45b2edd
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.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>

This patch modifies both versions of the translation table library
to use the mmap_attr_t type consistently wherever it is manipulating
MT_* attributes variables. It used to use mmap_attr_t or plain integer
types interchangeably, which compiles fine because an enumeration type
can be silently converted to an integer, but which is semantically
incorrect.

This patch removes this assumption by using the abstract type
'mmap_attr_t' all the time.

Change-Id: Id1f099025d2cb962b275bb7e39ad2c4dbb4e366c
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>

Added APIs to add and remove regions to the translation tables
dynamically while the MMU is enabled. Only static regions are allowed
to overlap other static ones (for backwards compatibility).

A new private attribute (MT_DYNAMIC / MT_STATIC) has been added to
flag each region as such.

The dynamic mapping functionality can be enabled or disabled when
compiling by setting the build option PLAT_XLAT_TABLES_DYNAMIC to 1
or 0. This can be done per-image.

TLB maintenance code during dynamic table mapping and unmapping has
also been added.

Fixes ARM-software/tf-issues#310

Change-Id: I19e8992005c4292297a382824394490c5387aa3b
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

The folder lib/xlat_tables_v2 has been created to store a new version
of the translation tables library for further modifications in patches
to follow. At the moment it only contains a basic implementation that
supports static regions.

This library allows different translation tables to be modified by
using different 'contexts'. For now, the implementation defaults to
the translation tables used by the current image, but it is possible
to modify other tables than the ones in use.

Added a new API to print debug information for the current state of
the translation tables, rather than printing the information while
the tables are being created. This allows subsequent debug printing
of the xlat tables after they have been changed, which will be useful
when dynamic regions are implemented in a patch to follow.

The common definitions stored in `xlat_tables.h` header have been moved
to a new file common to both versions, `xlat_tables_defs.h`.

All headers related to the translation tables library have been moved to
a the subfolder `xlat_tables`.

Change-Id: Ia55962c33e0b781831d43a548e505206dffc5ea9
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Each translation table level entry can only map a given virtual
address onto physical addresses of the same granularity. For example,
with the current configuration, a level 2 entry maps blocks of 2 MB,
so the physical address must be aligned to 2 MB. If the address is not
aligned, the MMU will just ignore the lower bits.

This patch adds an assertion to make sure that physical addresses are
always aligned to the correct boundary.

Change-Id: I0ab43df71829d45cdbe323301b3053e08ca99c2c
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Commit e8719552 removed some definitions related to translation
tables from the xlat_tables.h header file, based on the assumption
that they weren't used by any platform. These are actually used by
some partners so this patch restores them.

Fixes ARM-software/tf-issues#425

Change-Id: Idafa5f00bb0bd9c2847b5ae6541cf8db93c7b89a

Instead of hardcoding a level 1 table as the base translation level
table, let the code decide which level is the most appropriate given
the virtual address space size.

As the table granularity is 4 KB, this allows the code to select
level 0, 1 or 2 as base level for AArch64. This way, instead of
limiting the virtual address space width to 39-31 bits, widths of
48-25 bit can be used.

For AArch32, this change allows the code to select level 1 or 2
as the base translation level table and use virtual address space
width of 32-25 bits.

Also removed some unused definitions related to translation tables.

Fixes ARM-software/tf-issues#362

Change-Id: Ie3bb5d6d1a4730a26700b09827c79f37ca3cdb65

This patch adds translation library supports for AArch32 platforms.
The library only supports long descriptor formats for AArch32.
The `enable_mmu_secure()` enables the MMU for secure world with
`TTBR0` pointing to the populated translation tables.

Change-Id: I061345b1779391d098e35e7fe0c76e3ebf850e08

This patch introduces the MT_EXECUTE/MT_EXECUTE_NEVER memory mapping
attributes in the translation table library to specify the
access permissions for instruction execution of a memory region.
These new attributes should be used only for normal, read-only
memory regions. For other types of memory, the translation table
library still enforces the following rules, regardless of the
MT_EXECUTE/MT_EXECUTE_NEVER attribute:

 - Device memory is always marked as execute-never.
 - Read-write normal memory is always marked as execute-never.

Change-Id: I8bd27800a8c1d8ac1559910caf4a4840cf25b8b0

As of commit e1ea9290, if the attributes of an inner memory region
are different than the outer region, new page tables are generated
regardless of how "restrictive" they are. This patch removes an
out-dated comment still referring to the old priority system based
on which attributes were more restrictive.

Change-Id: Ie7fc1629c90ea91fe50315145f6de2f3995e5e00