Commit Graph

244 Commits

Author SHA1 Message Date
David Wang d40ab484d2 Add support for Cortex-A75 and Cortex-A55 CPUs
Both Cortex-A75 and Cortex-A55 CPUs use the ARM DynamIQ Shared Unit
(DSU). The power-down and power-up sequences are therefore mostly
managed in hardware, and required software operations are considerably
simpler.

Change-Id: I68b30e6e1ebe7c041d5e67f39c59f08575fc7ecc
Co-authored-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
2017-06-01 11:44:52 +01:00
dp-arm 4df2246943 compiler-rt: Remove unused int_util.[ch] files
Change-Id: I32fc523e3178b7e50191682241904d52499ff708
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
2017-05-24 15:39:28 +01:00
dp-arm 22fa58cbfa Use a callee-saved register to be AAPCS-compliant
x8 is not a callee-saved register and can be corrupted.
Use x19 instead to be AAPCS-compliant.

Fixes ARM-software/tf-issues#478

Change-Id: Ib4f114c36f4c11351ae856f953c45dca92b27c3b
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
2017-05-24 14:23:08 +01:00
danh-arm 6cfba92c0a Merge pull request #945 from antonio-nino-diaz-arm/an/xlat-dependency
xlat: Fix missing header file dependency
2017-05-22 15:29:12 +01:00
danh-arm 81602a9791 Merge pull request #939 from dp-arm/dp/AArch32_tbbr
Add TBBR and FWU support for AArch32
2017-05-22 15:28:17 +01:00
Antonio Nino Diaz b506f304f7 xlat: Fix missing header file dependency
xlat_tables_arch.h uses the platform macro `PLAT_VIRT_ADDR_SPACE_SIZE`.
This macro is defined in xlat_tables_private.h only if the platform
still uses the deprecated `ADDR_SPACE_SIZE`.

Change-Id: I1c3b12ebd96bdfe9bf94b26d440c03bc0f8c0b24
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
2017-05-18 15:25:12 +01:00
Antonio Nino Diaz 0da2fe7e29 Simplify assert() to reduce memory usage
The behaviour of assert() now depends on the value of the new optional
platform define `PLAT_LOG_LEVEL_ASSERT`. This defaults to `LOG_LEVEL` if
not defined by the platform.

- If `PLAT_LOG_LEVEL_ASSERT` >= `LOG_LEVEL_VERBOSE`, it prints the file
  name, line and asserted expression.
- If `PLAT_LOG_LEVEL_ASSERT` >= `LOG_LEVEL_INFO`, it prints the file
  name and line.
- If not, it doesn't print anything.

Note the old behaviour was to print the function name whereas now it
prints the file name. This reduces memory usage because the file name is
shared between all assert calls in a given file. Also, the default
behaviour in debug builds is to no longer print the asserted expression,
greatly reducing the string usage.

For FVP debug builds this change saves approximately:

              No TBBR    TBBR
        BL1    1.6 KB   2.2 KB
        BL2    1.7 KB   2.1 KB
        BL31   2.6 KB   3.3 KB

Change-Id: I2947569d593df0b25611dc3c7a6096f42155c115
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
2017-05-16 09:58:08 +01:00
davidcunado-arm 823cc7a9d2 Merge pull request #930 from antonio-nino-diaz-arm/an/fixes-xlat-v2
Minor fixes to the xlat tables lib v2
2017-05-12 22:48:34 +01:00
dp-arm d801fbb0fc Hook up LLVM compiler-rt in the build system
This patch enables compiler-rt for the AArch32 target.  The code is
not used for AArch64 as the architecture supports the 64-bit division
and modulo operations natively.

Change-Id: I1703a92872b0bb56ac0b98c67193830683963b13
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
2017-05-12 11:54:12 +01:00
dp-arm 0e14a7fbeb Import builtins from LLVM compiler-rt project
These are needed to provide division and modulo operations
for the AArch32 target.

This code is entirely unmodified.  Imported from compiler-rt
master branch as of May 4 2017.

Change-Id: I001e1809f2afd4bf8d4cc3d2296798809f607144
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
2017-05-12 11:54:12 +01:00
davidcunado-arm d6104f5ab4 Merge pull request #927 from jeenu-arm/state-switch
Execution state switch
2017-05-11 16:04:52 +01:00
Antonio Nino Diaz e769db3eb8 Minor fixes to the xlat tables lib v2
- 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>
2017-05-09 11:05:05 +01:00
davidcunado-arm 5e62327786 Merge pull request #924 from antonio-nino-diaz-arm/an/fix-xn-bit
Fix execute-never permissions in xlat tables libs
2017-05-05 09:50:34 +01:00
davidcunado-arm f132b4a05b Merge pull request #925 from dp-arm/dp/spdx
Use SPDX license identifiers
2017-05-04 16:35:19 +01:00
Jeenu Viswambharan b10d44995e Introduce ARM SiP service to switch execution state
In AArch64, privileged exception levels control the execution state
(a.k.a. register width) of the immediate lower Exception Level; i.e.
whether the lower exception level executes in AArch64 or AArch32 state.
For an exception level to have its execution state changed at run time,
it must request the change by raising a synchronous exception to the
higher exception level.

This patch implements and adds such a provision to the ARM SiP service,
by which an immediate lower exception level can request to switch its
execution state. The execution state is switched if the request is:

  - raised from non-secure world;

  - raised on the primary CPU, before any secondaries are brought online
    with CPU_ON PSCI call;

  - raised from an exception level immediately below EL3: EL2, if
    implemented; otherwise NS EL1.

If successful, the SMC doesn't return to the caller, but to the entry
point supplied with the call. Otherwise, the caller will observe the SMC
returning with STATE_SW_E_DENIED code. If ARM Trusted Firmware is built
for AArch32, the feature is not supported, and the call will always
fail.

For the ARM SiP service:

  - Add SMC function IDs for both AArch32 and AArch64;
  - Increment the SiP service minor version to 2;
  - Adjust the number of supported SiP service calls.

Add documentation for ARM SiP service.

Fixes ARM-software/tf-issues#436

Change-Id: I4347f2d6232e69fbfbe333b340fcd0caed0a4cea
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
2017-05-04 11:00:34 +01:00
dp-arm 82cb2c1ad9 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>
2017-05-03 09:39:28 +01:00
Jeenu Viswambharan f4c8aa9054 Add macro to check whether the CPU implements an EL
Replace all instances of checks with the new macro.

Change-Id: I0eec39b9376475a1a9707a3115de9d36f88f8a2a
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
2017-05-02 16:11:12 +01:00
Antonio Nino Diaz a56402521f Fix execute-never permissions in xlat tables libs
Translation regimes that only support one virtual address space (such as
the ones for EL2 and EL3) can flag memory regions as execute-never by
setting to 1 the XN bit in the Upper Attributes field in the translation
tables descriptors. Translation regimes that support two different
virtual address spaces (such as the one shared by EL1 and EL0) use bits
PXN and UXN instead.

The Trusted Firmware runs at EL3 and EL1, it has to handle translation
tables of both translation regimes, but the previous code handled both
regimes the same way, as if both had only 1 VA range.

When trying to set a descriptor as execute-never it would set the XN
bit correctly in EL3, but it would set the XN bit in EL1 as well. XN is
at the same bit position as UXN, which means that EL0 was being
prevented from executing code at this region, not EL1 as the code
intended. Therefore, the PXN bit was unset to 0 all the time. The result
is that, in AArch64 mode, read-only data sections of BL2 weren't
protected from being executed.

This patch adds support of translation regimes with two virtual address
spaces to both versions of the translation tables library, fixing the
execute-never permissions for translation tables in EL1.

The library currently does not support initializing translation tables
for EL0 software, therefore it does not set/unset the UXN bit. If EL1
software needs to initialize translation tables for EL0 software, it
should use a different library instead.

Change-Id: If27588f9820ff42988851d90dc92801c8ecbe0c9
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
2017-05-02 15:34:01 +01:00
davidcunado-arm 062dd37828 Merge pull request #923 from nmenon/fix_xlat_1
xlat lib: Don't set mmap_attr_t enum to be -1
2017-05-02 15:32:23 +01:00
Nishanth Menon 7055e6fa32 xlat lib: Don't set mmap_attr_t enum to be -1
-1 is not a defined mmap_attr_t type. Instead of using invalid enum
types, we can either choose to define a INVALID type OR handle the
condition specifically.

Since the usage of mmap_region_attr is limited, it is easier to just
handle the error condition specifically and return 0 or -1 depending
on success or fail.

Fixes: ARM-Software/tf-issues#473
Fixes: 28fa2e9ee8 ("xlat lib: Use mmap_attr_t type consistently")

Signed-off-by: Nishanth Menon <nm@ti.com>
2017-05-02 07:05:42 -05:00
Scott Branden 0f22bef31d Merge branch 'integration' into tf_issue_461 2017-04-29 08:36:12 -07:00
Scott Branden 53d9c9c85b Move defines in utils.h to utils_def.h to fix shared header compile issues
utils.h is included in various header files for the defines in it.
Some of the other header files only contain defines.  This allows the
header files to be shared between host and target builds for shared defines.

Recently types.h has been included in utils.h as well as some function
prototypes.

Because of the inclusion of types.h conflicts exist building host tools
abd these header files now.  To solve this problem,
move the defines to utils_def.h and have this included by utils.h and
change header files to only include utils_def.h and not pick up the new
types.h being introduced.

Fixes ARM-software/tf-issues#461

Signed-off-by: Scott Branden <scott.branden@broadcom.com>

Remove utils_def.h from utils.h

This patch removes utils_def.h from utils.h as it is not required.
And also makes a minor change to ensure Juno platform compiles.

Change-Id: I10cf1fb51e44a8fa6dcec02980354eb9ecc9fa29
2017-04-29 08:30:05 -07:00
davidcunado-arm 0c7c44110e Merge pull request #909 from sandrine-bailleux-arm/sb/xlat-lib-misc-improvements
xlat lib: Use mmap_attr_t type consistently
2017-04-24 14:40:16 +01:00
davidcunado-arm 484acce376 Merge pull request #910 from dp-arm/dp/AArch32-juno-port
Add AArch32 support for Juno
2017-04-21 17:10:27 +01:00
davidcunado-arm e83b5fdc7a Merge pull request #898 from soby-mathew/sm/dcache-early
PSCI: Build option to enable D-Caches early in warmboot
2017-04-21 11:45:53 +01:00
Yatharth Kochar dc787588a5 AArch32: Add support for ARM Cortex-A53/57/72 MPCore Processor
This patch adds AArch32 state support for ARM Cortex-A53,
Cortex-A57 and Cortex-A72 MPCore Processor in the CPU specific
operations framework.

NOTE: CPU errata handling code is not present in this patch.

Change-Id: I01eb3e028e40dde37565707ebc99e06e7a0c113d
Signed-off-by: Yatharth Kochar <yatharth.kochar@arm.com>
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
2017-04-20 15:05:21 +01:00
Sandrine Bailleux 28fa2e9ee8 xlat lib: Use mmap_attr_t type consistently
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>
2017-04-20 13:01:24 +01:00
Antonio Nino Diaz aa61368eb5 Control inclusion of helper code used for asserts
Many asserts depend on code that is conditionally compiled based on the
DEBUG define. This patch modifies the conditional inclusion of such code
so that it is based on the ENABLE_ASSERTIONS build option.

Change-Id: I6406674788aa7e1ad7c23d86ce94482ad3c382bd
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
2017-04-20 09:59:12 +01:00
Antonio Nino Diaz 044bb2faab Remove build option `ASM_ASSERTION`
The build option `ENABLE_ASSERTIONS` should be used instead. That way
both C and ASM assertions can be enabled or disabled together.

All occurrences of `ASM_ASSERTION` in common code and ARM platforms have
been replaced by `ENABLE_ASSERTIONS`.

ASM_ASSERTION has been removed from the user guide.

Change-Id: I51f1991f11b9b7ff83e787c9a3270c274748ec6f
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
2017-04-20 09:58:28 +01:00
Antonio Nino Diaz cc8b56322b Add `ENABLE_ASSERTIONS` build option
Add the new build option `ENABLE_ASSERTIONS` that controls whether or
not assert functions are compiled out. It defaults to 1 for debug builds
and to 0 for release builds.

Additionally, a following patch will be done to allow this build option
to hide auxiliary code used for the checks done in an `assert()`. This
code is is currently under the DEBUG build flag.

Assert messages are now only printed if LOG_LEVEL >= LOG_LEVEL_INFO,
which is the default for debug builds.

This patch also updates the User Guide.

Change-Id: I1401530b56bab25561bb0f274529f1d12c5263bc
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
2017-04-19 16:00:53 +01:00
Soby Mathew bcc3c49c90 PSCI: Build option to enable D-Caches early in warmboot
This patch introduces a build option to enable D-cache early on the CPU
after warm boot. This is applicable for platforms which do not require
interconnect programming to enable cache coherency (eg: single cluster
platforms). If this option is enabled, then warm boot path enables
D-caches immediately after enabling MMU.

Fixes ARM-Software/tf-issues#456

Change-Id: I44c8787d116d7217837ced3bcf0b1d3441c8d80e
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
2017-04-19 12:07:05 +01:00
davidcunado-arm f07d3985b8 Merge pull request #885 from antonio-nino-diaz-arm/an/console-flush
Implement console_flush()
2017-04-12 22:23:44 +01:00
Douglas Raillard 51faada71a 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>
2017-03-31 13:58:48 +01:00
Antonio Nino Diaz 1e09ff9344 Remove dead loops in assert() in C and ASM
The desired behaviour is to call `plat_panic_handler()`, and to use
`no_ret` to do so from ASM.

Change-Id: I88b2feefa6e6c8f9bf057fd51ee0d2e9fb551e4f
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
2017-03-31 09:54:22 +01:00
Antonio Nino Diaz 0b32628edd Flush console where necessary
Call console_flush() before execution either terminates or leaves an
exception level.

Fixes: ARM-software/tf-issues#123

Change-Id: I64eeb92effb039f76937ce89f877b68e355588e3
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
2017-03-31 09:54:22 +01:00
davidcunado-arm e422f991df Merge pull request #880 from Summer-ARM/sq/tcr-memory-attribution
Add support to change xlat_tables to non-cacheable
2017-03-29 17:54:54 +01:00
davidcunado-arm ab13990204 Merge pull request #870 from douglas-raillard-arm/dr/remove_asm_signed_test
Replace ASM signed tests with unsigned
2017-03-29 09:58:20 +01:00
Summer Qin 5d21b037e1 Add support to change xlat_tables to non-cacheable
This patch adds an additional flag `XLAT_TABLE_NC` which marks the
translation tables as Non-cacheable for MMU accesses.

Change-Id: I7c28ab87f0ce67da237fadc3627beb6792860fd4
Signed-off-by: Summer Qin <summer.qin@arm.com>
2017-03-28 10:32:17 +01:00
Andre Przywara b75dc0e41c Add workaround for ARM Cortex-A53 erratum 855873
ARM erratum 855873 applies to all Cortex-A53 CPUs.
The recommended workaround is to promote "data cache clean"
instructions to "data cache clean and invalidate" instructions.
For core revisions of r0p3 and later this can be done by setting a bit
in the CPUACTLR_EL1 register, so that hardware takes care of the promotion.
As CPUACTLR_EL1 is both IMPLEMENTATION DEFINED and can be trapped to EL3,
we set the bit in firmware.
Also we dump this register upon crashing to provide more debug
information.

Enable the workaround for the Juno boards.

Change-Id: I3840114291958a406574ab6c49b01a9d9847fec8
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
2017-03-20 10:57:46 +00:00
Douglas Raillard 355a5d0336 Replace ASM signed tests with unsigned
ge, lt, gt and le condition codes in assembly provide a signed test
whereas hs, lo, hi and ls provide the unsigned counterpart. Signed tests
should only be used when strictly necessary, as using them on logically
unsigned values can lead to inverting the test for high enough values.
All offsets, addresses and usually counters are actually unsigned
values, and should be tested as such.

Replace the occurrences of signed condition codes where it was
unnecessary by an unsigned test as the unsigned tests allow the full
range of unsigned values to be used without inverting the result with
some large operands.

Change-Id: I58b7e98d03e3a4476dfb45230311f296d224980a
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
2017-03-20 10:38:43 +00:00
davidcunado-arm 3944adca59 Merge pull request #861 from soby-mathew/sm/aarch32_fixes
Misc AArch32 fixes
2017-03-18 12:16:27 +00:00
davidcunado-arm 510a9de79f Merge pull request #860 from jeenu-arm/hw-asstd-coh
Patches for platforms with hardware-assisted coherency
2017-03-17 12:34:37 +00:00
davidcunado-arm 28ee754d15 Merge pull request #856 from antonio-nino-diaz-arm/an/dynamic-xlat
Introduce version 2 of the translation tables library
2017-03-16 12:42:32 +00:00
Antonio Nino Diaz ccbec91c0c Apply workaround for errata 813419 of Cortex-A57
TLBI instructions for EL3 won't have the desired effect under specific
circumstances in Cortex-A57 r0p0. The workaround is to execute DSB and
TLBI twice each time.

Even though this errata is only needed in r0p0, the current errata
framework is not prepared to apply run-time workarounds. The current one
is always applied if compiled in, regardless of the CPU or its revision.

This errata has been enabled for Juno.

The `DSB` instruction used when initializing the translation tables has
been changed to `DSB ISH` as an optimization and to be consistent with
the barriers used for the workaround.

Change-Id: Ifc1d70b79cb5e0d87e90d88d376a59385667d338
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
2017-03-08 14:40:27 +00:00
Antonio Nino Diaz 0b64f4ef43 Add dynamic region support to xlat tables lib v2
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>
2017-03-08 14:40:27 +00:00
Antonio Nino Diaz f10644c569 Improve debug output of the translation tables
The printed output has been improved in two ways:

- Whenever multiple invalid descriptors are found, only the first one
  is printed, and a line is added to inform about how many descriptors
  have been omitted.

- At the beginning of each line there is an indication of the table
  level the entry belongs to. Example of the new output:
  `[LV3] VA:0x1000 PA:0x1000 size:0x1000 MEM-RO-S-EXEC`

Change-Id: Ib6f1cd8dbd449452f09258f4108241eb11f8d445
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
2017-03-08 14:40:27 +00:00
Antonio Nino Diaz 7bb01fb29a Add version 2 of xlat tables library
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>
2017-03-08 14:40:23 +00:00
Soby Mathew 61531a274d AArch32: Fix normal memory bakery compilation
This patch fixes a compilation issue with bakery locks when
PSCI library is compiled with USE_COHERENT_MEM = 0 build option.

Change-Id: Ic7f6cf9f2bb37f8a946eafbee9cbc3bf0dc7e900
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
2017-03-02 15:43:17 +00:00
davidcunado-arm bea7caff8d Merge pull request #853 from vwadekar/tegra-changes-from-downstream-v3
Tegra changes from downstream v3
2017-03-02 15:27:33 +00:00
Jeenu Viswambharan b0408e87f7 PSCI: Optimize call paths if all participants are cache-coherent
The current PSCI implementation can apply certain optimizations upon the
assumption that all PSCI participants are cache-coherent.

  - Skip performing cache maintenance during power-up.

  - Skip performing cache maintenance during power-down:

    At present, on the power-down path, CPU driver disables caches and
    MMU, and performs cache maintenance in preparation for powering down
    the CPU. This means that PSCI must perform additional cache
    maintenance on the extant stack for correct functioning.

    If all participating CPUs are cache-coherent, CPU driver would
    neither disable MMU nor perform cache maintenance. The CPU being
    powered down, therefore, remain cache-coherent throughout all PSCI
    call paths. This in turn means that PSCI cache maintenance
    operations are not required during power down.

  - Choose spin locks instead of bakery locks:

    The current PSCI implementation must synchronize both cache-coherent
    and non-cache-coherent participants. Mutual exclusion primitives are
    not guaranteed to function on non-coherent memory. For this reason,
    the current PSCI implementation had to resort to bakery locks.

    If all participants are cache-coherent, the implementation can
    enable MMU and data caches early, and substitute bakery locks for
    spin locks. Spin locks make use of architectural mutual exclusion
    primitives, and are lighter and faster.

The optimizations are applied when HW_ASSISTED_COHERENCY build option is
enabled, as it's expected that all PSCI participants are cache-coherent
in those systems.

Change-Id: Iac51c3ed318ea7e2120f6b6a46fd2db2eae46ede
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
2017-03-02 11:00:20 +00:00