At the moment we have some elaborate, but very schematic functions to
allow checking for CPU feature enablement. Adding some more becomes
tedious and is also error-prone.
Provide two wrapper macros that reduce most of the features to a
single line:
- CREATE_FEATURE_FUNCS(name, idreg, idfield, guard)
creates two functions read_<name>_id_field() and is_<name>_supported(),
that check the 4-bit CPU ID field starting at bit <idfield> in <idreg>
for being not 0, and compares it against the build time <guard> symbol.
For the usual feature (like PAN) this looks like:
CREATE_FEATURE_FUNCS(feat_pan, id_aa64mmfr1_el1,
ID_AA64MMFR1_EL1_PAN_SHIFT, ENABLE_FEAT_PAN)
- CREATE_FEATURE_FUNCS_VER(name, read_func, idvalue, guard)
creates one function to check for a certain CPU ID field *value*, so
when "!= 0" is not sufficient. It's meant to be used in addition to
the above macro, since that generates the CPU ID field accessor
function:
CREATE_FEATURE_FUNCS(feat_amu, id_aa64pfr0_el1, ID_AA64PFR0_AMU_SHIFT,
ENABLE_FEAT_AMU)
CREATE_FEATURE_FUNCS_VER(feat_amuv1p1, read_feat_amu_id_field,
ID_AA64PFR0_AMU_V1P1, ENABLE_FEAT_AMUv1p1)
Describe the existing feature accessor functions using those new macros,
to reduce the size of the file, improve readability and decrease the
possibility of (copy&paste) bugs.
Change-Id: Ib136a875b4857058ff561c4635ace344006f29bf
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
The FEAT_MTPMU feature disable runs very early after reset. This means,
it needs to be written in assembly, since the C runtime has not been
initialised yet.
However, there is no need for it to be initialised so soon. The PMU
state is only relevant after TF-A has relinquished control. The code
to do this is also very verbose and difficult to read. Delaying the
initialisation allows for it to happen with the rest of the PMU. Align
with FEAT_STATE in the process.
BREAKING CHANGE: This patch explicitly breaks the EL2 entry path. It is
currently unsupported.
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: I2aa659d026fbdb75152469f6d19812ece3488c6f
The enablement code for the PMU is scattered and difficult to track
down. Factor out the feature into its own lib/extensions folder and
consolidate the implementation. Treat it is as an architecturally
mandatory feature as it is currently.
Additionally, do some cleanup on AArch64. Setting overflow bits in
PMCR_EL0 is irrelevant for firmware so don't do it. Then delay the PMU
initialisation until the context management stage which simplifies the
early environment assembly. One side effect is that the PMU might count
before this happens so reset all counters to 0 to prevent any leakage.
Finally, add an enable to manage_extensions_realm() as realm world uses
the pmu. This introduces the HPMN fixup to realm world.
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: Ie13a8625820ecc5fbfa467dc6ca18025bf6a9cd3
At the moment we only support FEAT_RAS to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (FEAT_RAS=2), by splitting
is_armv8_2_feat_ras_present() into an ID register reading function and
a second function to report the support status. That function considers
both build time settings and runtime information (if needed), and is
used before we access RAS related registers.
Also move the context saving code from assembly to C, and use the new
is_feat_ras_supported() function to guard its execution.
Change the FVP platform default to the now supported dynamic
option (=2), so the right decision can be made by the code at runtime.
Change-Id: I30498f72fd80b136850856244687400456a03d0e
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
The current usage of RAS_EXTENSION in TF-A codebase is to cater for two
things in TF-A :
1. Pull in necessary framework and platform hooks for Firmware first
handling(FFH) of RAS errors.
2. Manage the FEAT_RAS extension when switching the worlds.
FFH means that all the EAs from NS are trapped in EL3 first and signaled
to NS world later after the first handling is done in firmware. There is
an alternate way of handling RAS errors viz Kernel First handling(KFH).
Tying FEAT_RAS to RAS_EXTENSION build flag was not correct as the
feature is needed for proper handling KFH in as well.
This patch breaks down the RAS_EXTENSION flag into a flag to denote the
CPU architecture `ENABLE_FEAT_RAS` which is used in context management
during world switch and another flag `RAS_FFH_SUPPORT` to pull in
required framework and platform hooks for FFH.
Proper support for KFH will be added in future patches.
BREAKING CHANGE: The previous RAS_EXTENSION is now deprecated. The
equivalent functionality can be achieved by the following
2 options:
- ENABLE_FEAT_RAS
- RAS_FFH_SUPPORT
Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: I1abb9ab6622b8f1b15712b12f17612804d48a6ec
FEAT_SME2 is an extension of FEAT_SME and an optional feature
from v9.2. Its an extension of SME, wherein it not only
processes matrix operations efficiently, but also provides
outer-product instructions to accelerate matrix operations.
It affords instructions for multi-vector operations.
Further, it adds an 512 bit architectural register ZT0.
This patch implements all the changes introduced with FEAT_SME2
to ensure that the instructions are allowed to access ZT0
register from Non-secure lower exception levels.
Additionally, it adds support to ensure FEAT_SME2 is aligned
with the existing FEATURE DETECTION mechanism, and documented.
Change-Id: Iee0f61943304a9cfc3db8f986047b1321d0a6463
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
At the moment we only support FEAT_DIT to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (ENABLE_DIT=2), by splitting
is_armv8_4_dit_present() into an ID register reading function and a
second function to report the support status. That function considers
both build time settings and runtime information (if needed).
We use ENABLE_DIT in two occassions in assembly code, where we just set
the DIT bit in the DIT system register.
Protect those two cases by reading the CPU ID register when ENABLE_DIT
is set to 2.
Change the FVP platform default to the now supported dynamic
option (=2), so the right decision can be made by the code at runtime.
Change-Id: I506d352f18e23c60db8cdf08edb449f60adbe098
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Arm v9.4 introduces support for Guarded Control Stack, providing
mitigations against some forms of RPO attacks and an efficient mechanism
for obtaining the current call stack without requiring a full stack
unwind. Enable access to this feature for EL2 and below, context
switching the newly added EL2 registers as appropriate.
Change the FVP platform to default to handling this as a dynamic option
so the right decision can be made by the code at runtime.
Signed-off-by: Mark Brown <broonie@kernel.org>
Change-Id: I691aa7c22e3547bb3abe98d96993baf18c5f0e7b
Arm v8.9 introduces a series of features providing a new way to set memory
permissions. Instead of directly encoding the permissions in the page
tables the PTEs contain indexes into an array of permissions stored in
system registers, allowing greater flexibility and density of encoding.
Enable access to these features for EL2 and below, context switching the
newly added EL2 registers as appropriate. Since all of FEAT_S[12]P[IO]E
are separately discoverable we have separate build time options for
enabling them, but note that there is overlap in the registers that they
implement and the enable bit required for lower EL access.
Change the FVP platform to default to handling them as dynamic options so
the right decision can be made by the code at runtime.
Signed-off-by: Mark Brown <broonie@kernel.org>
Change-Id: Icf89e444e39e1af768739668b505661df18fb234
Add support for runtime detection (ENABLE_SVE_FOR_NS=2), by splitting
sve_supported() into an ID register reading function and a
second function to report the support status. That function considers
both build time settings and runtime information (if needed), and is
used before we do SVE specific setup.
Change the FVP platform default to the now supported dynamic
option (=2), so the right decision can be made by the code at runtime.
Change-Id: I1caaba2216e8e2a651452254944a003607503216
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Add support for runtime detection (ENABLE_SME_FOR_NS=2), by splitting
feat_sme_supported() into an ID register reading function and a
second function to report the support status. That function considers
both build time settings and runtime information (if needed), and is
used before we do SME specific setup.
Change the FVP platform default to the now supported dynamic option
(=2),so the right decision can be made by the code at runtime.
Change-Id: Ida9ccf737db5be20865b84f42b1f9587be0626ab
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
The AMU extension code was using its own feature detection routines.
Replace them with the generic CPU feature handlers (defined in
arch_features.h), which get updated to cover the v1p1 variant as well.
Change-Id: I8540f1e745d7b02a25a6c6cdf2a39d6f5e21f2aa
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
So far we have the ENABLE_AMU build option to include AMU register
handling code for enabling and context switch. There is also an
ENABLE_FEAT_AMUv1 option, solely to protect the HAFGRTR_EL2 system
register handling. The latter needs some alignment with the new feature
scheme, but it conceptually overlaps with the ENABLE_AMU option.
Since there is no real need for two separate options, unify both into a
new ENABLE_FEAT_AMU name in a first step. This is mostly just renaming at
this point, a subsequent patch will make use of the new feature handling
scheme.
Change-Id: I97d8a55bdee2ed1e1509fa9f2b09fd0bdd82736e
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
At the moment we only support for FEAT_RNG to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (FEAT_RNG=2), by splitting
is_armv8_5_rng_present() into an ID register reading function and a second
function to report the support status. That function considers both build
time settings and runtime information (if needed), and is used before we
access the RNDRRS system register.
Change the QEMU platform default to the now supported dynamic option (=2),
so the right decision can be made by the code at runtime.
Change-Id: I1a4a538d5ad395fead7324f297d0056bda4f84cb
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
In ARMv8.4, the EL2 exception level got added to the secure world.
Adapt and rename the existing is_armv8_4_sel2_present() function, to
align its handling with the other CPU features.
Change-Id: If11e1942fdeb63c63f36ab9e89be810347d1a952
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
At the moment we only support for FEAT_NV2 to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (CTX_INCLUDE_NEVE_REGS=2), by
splitting get_armv8_4_feat_nv_support() into an ID register reading
function and a second function to report the support status. That
function considers both build time settings and runtime information
(if needed), and is used before we access the VNCR_EL2 system register.
Also move the context saving code from assembly to C, and use the new
is_feat_nv2_supported() function to guard its execution.
Change the FVP platform default to the now supported dynamic option (=2),
so the right decision can be made by the code at runtime.
Change-Id: I85b080641995fb72cfd4ac933f7a3f75770c2cb9
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
At the moment we only support FEAT_TWED to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (ENABLE_FEAT_TWED=2), by splitting
is_armv8_6_twed_present() into an ID register reading function and a
second function to report the support status. That function considers
both build time settings and runtime information (if needed), and is
used before we set the trap delay time.
Change the FVP platform default to the now supported dynamic option (=2),
so the right decision can be made by the code at runtime.
Change-Id: I58626230ef0af49886c0a197abace01e81f661d2
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
At the moment we only support FEAT_CSV2_2 to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (ENABLE_FEAT_CSV2_2=2), by splitting
is_armv8_0_feat_csv2_2_present() into an ID register reading function
and a second function to report the support status. That function
considers both build time settings and runtime information (if needed),
and is used before we access the SCXTNUM_EL2 system register.
Also move the context saving code from assembly to C, and use the new
is_feat_csv2_2_supported() function to guard its execution.
Change the FVP platform default to the now supported dynamic option (=2),
so the right decision can be made by the code at runtime.
Change-Id: I89c7bc883e6a65727fdbdd36eb3bfbffb2196da7
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
At the moment we only support FEAT_ECV to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (ENABLE_FEAT_ECV=2), by splitting
is_feat_ecv_present() into an ID register reading function and a second
function to report the support status. That function considers both
build time settings and runtime information (if needed), and is used
before we access the CNTPOFF_EL2 system register.
Also move the context saving code from assembly to C, and use the new
is_feat_ecv_supported() function to guard its execution.
Change the FVP platform default to the now supported dynamic option (=2),
so the right decision can be made by the code at runtime.
Change-Id: I4acd5384929f1902b62a87ae073aafa1472cd66b
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
At the moment we only support FEAT_PAN to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (ENABLE_FEAT_PAN=2), by splitting
is_armv8_1_pan_present() into an ID register reading function and a
second function to report the support status. That function considers
both build time settings and runtime information (if needed), and is
used before we PAN specific setup.
Change the FVP platform default to the now supported dynamic option (=2),
so the right decision can be made by the code at runtime.
Change-Id: I58e5fe8d3c9332820391c7d93a8fb9dba4cf754a
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
FEAT_SB introduces a new speculation barrier instruction, that is more
lightweight than a "dsb; isb" combination. We use that in a hot path,
so cannot afford and don't want a runtime detection mechanism.
Nevertheless align the implementation of the feature detection part
with the other features, but renaming the detection function, and
updating the FEAT_DETECTION code. Also update the documentation.
Change-Id: I2b86dfd1ad259c3bb99ab5186e2911ace454b54c
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
The MPAM CPU ID version number is split between two CPU ID register
fields, with the second being a fractional field, allowing for instance
for a "MPAM v1.1" number. The read_feat_mpam_version() function merges
those two fields to form a "4.4" fixed point fractional number, but the
limit check in the check_feature() function was not taking this into
account.
To support MPAM major version 1, extend the limit from "1" to "17", to
cover the current maximum version of "MPAM v1.1".
This fixes FVP runs with "has_mpam=1" and FEATURE_DETECTION enabled.
Change-Id: Icb557741d597e4e43eaf658b78f18af6e9fb439e
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
At the moment we only support FEAT_VHE to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (ENABLE_FEAT_VHE=2), by splitting
is_armv8_1_vhe_present() into an ID register reading function and a
second function to report the support status. That function considers
both build time settings and runtime information (if needed), and is
used before we access VHE related registers.
Also move the context saving code from assembly to C, and use the new
is_feat_vhe_supported() function to guard its execution.
Enable VHE in its runtime detection version for all FVP builds.
Change-Id: Ib397cd0c83e8c709bd6fed603560e39901fa672b
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
At the moment we only support FEAT_MPAM to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (ENABLE_MPAM_FOR_LOWER_ELS=2), by
splitting get_mpam_version() into an ID register reading
function and a second function to report the support status. That
function considers both build time settings and runtime information (if
needed), and is used before we access MPAM related registers.
Also move the context saving code from assembly to C, and use the new
is_feat_mpam_supported() function to guard its execution.
ENABLE_MPAM_FOR_LOWER_ELS defaults to 0, so add a stub enable function
to cover builds with compiler optimisations turned off. The unused
mpam_enable() function call will normally be optimised away (because it
would never be called), but with -O0 the compiler will leave the symbol
in the object file.
Change-Id: I531d87cb855a7c43471f861f625b5a6d4bc61313
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Arm v8.9 introduces FEAT_TCR2, adding extended translation control
registers. Support this, context switching TCR2_EL2 and disabling
traps so lower ELs can access the new registers.
Change the FVP platform to default to handling this as a dynamic option so
the right decision can be made by the code at runtime.
Signed-off-by: Mark Brown <broonie@kernel.org>
Change-Id: I297452acd8646d58bac64fc15e05b06a543e5148
At the moment we only support FEAT_TRF to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (ENABLE_TRF_FOR_NS=2), by splitting
is_feat_trf_present() into an ID register reading function and a second
function to report the support status. That function considers both
build time settings and runtime information (if needed), and is used
before we access TRF related registers.
Also move the context saving code from assembly to C, and use the new
is_feat_trf_supported() function to guard its execution.
The FVP platform decided to compile in support unconditionally (=1),
even though FEAT_TRF is an ARMv8.4 feature, so is not available with the
FVP model's default command line.
Change that to the now supported dynamic option (=2), so the right
decision can be made by the code at runtime.
Change-Id: Ia97b01adbe24970a4d837afd463dc5506b7295a3
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
At the moment we only support FEAT_BRBE to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (ENABLE_BRBE_FOR_NS=2), by splitting
is_feat_brbe_present() into an ID register reading function and a second
function to report the support status. That function considers both
build time settings and runtime information (if needed), and is used
before we access BRBE related registers.
The FVP platform decided to compile in support unconditionally (=1),
even though FEAT_BRBE is an ARMv9 feature, so is not available with the
FVP model's default command line.
Change that to the now supported dynamic option (=2), so the right
decision can be made by the code at runtime.
Change-Id: I5f2e2c9648300f65f0fa9a5f8e2f34e73529d053
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
At the moment we only support FEAT_TRBE to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (ENABLE_TRBE_FOR_NS=2), by splitting
is_feat_trbe_present() into an ID register reading function and a second
function to report the support status. That function considers both
build time settings and runtime information (if needed), and is used
before we access TRBE related registers.
The FVP platform decided to compile in support unconditionally (=1),
even though FEAT_TRBE is an ARMv9 feature, so is not available with the
FVP model's default command line.
Change that to the now supported dynamic option (=2), so the right
decision can be made by the code at runtime.
Change-Id: Iee7f88ea930119049543a8a4a105389997e7692c
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
So far the check_feature() function compares the subfield of a CPU ID
register against 0, to learn if a feature is enabled or not.
This is problematic for checks that require a certain revision of a
feature, so we should check against a minimum version number instead.
On top of that we might need to add code to support newer versions of a
feature, so we should be alerted if new hardware introduces a higher
number.
Extend the check_feature() function to take two extra arguments: the
minimum version, and the greatest currently known number.
Then make sure that the CPU ID field is in this range.
Change-Id: I425b68535a2ba9eafd31854e74d142183b521cd5
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Use the generic check function in feat_detect.c, and split the feature
check into two functions, as done for FEAT_FGT before.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Change-Id: I0a4f973427c10d5d15c414ff5e12b18b7e645fae
For the FGT context save/restore operation, we need to look at the AMUv1
feature, so migrate this one over to the new scheme.
This uses the generic check function in feat_detect.c, and splits the
feature check into two functions, as was done before for FEAT_FGT.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Change-Id: I95ad797f15001b2c9d1800c9d4af33fba79e136f
Split the feature check for FEAT_FGT into two parts:
- A boolean function that just evaluates whether the feature is usable.
This takes build time flags into account, and only evaluates the CPU
feature ID registers when the flexible FEAT_STATE_CHECK method is
used.
- A "raw" function that returns the unfiltered CPU feature ID register.
Change the callers where needed, to give them the version they actually
want.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Change-Id: I9a041132d280451f5d9f653a62904f603b2a916d
To implement proper runtime checking of features, and to be able to
extend feat_detect.c to catch other cases, rework the FEAT_FGT check to
directly call a generic function instead of providing a trivial specific
one. The #ifdef is moved into the function, and rewritten as a proper C
if statement.
We need to force the compiler to inline that function, otherwise the
optimisation won't work, once we exceed a certain number of callers.
This starts with FEAT_FGT, but all the other features will be moved over
eventually, in separate patches.
For all features checked this way, we delay the panic() until after
every feature has been checked, to list them all during one run.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Change-Id: Ic576922ff2c4f8d3c1b87b5843b3626729fe4514
The FEATURE_DETECTION functionality had some definitions in a header
file, although they were only used internally in the .c file.
Move them over there, since there are of no interest to other users.
Also use the opportuntiy to rename the less telling FEAT_STATE_[12]
names, and let the "0" case join the game. We use DISABLED, ALWAYS, and
CHECK now, so that the casual reader has some idea what those numbers
are supposed to mean.
feature_panic() becomes "static inline", since disabling all features
makes it unused, so the compiler complains otherwise.
Finally add a new category "cpufeat" to cover CPU feature related
changes.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Change-Id: If0c8ba91ad22440260ccff383c33bdd055eefbdc
FEAT_RNG_TRAP introduces support for EL3 trapping of reads of the
RNDR and RNDRRS registers, which is enabled by setting the
SCR_EL3.TRNDR bit. This patch adds a new build flag
ENABLE_FEAT_RNG_TRAP that enables the feature.
This feature is supported only in AArch64 state from Armv8.5 onwards.
Signed-off-by: Juan Pablo Conde <juanpablo.conde@arm.com>
Change-Id: Ia9f17aef3444d3822bf03809036a1f668c9f2d89
This change adds "FEAT_TRBE" to be part of feature detection mechanism.
Previously feature enablement flags were of boolean type, containing
either 0 or 1. With the introduction of feature detection procedure
we now support three states for feature enablement build flags(0 to 2).
Accordingly, "ENABLE_TRBE_FOR_NS" flag is now modified from boolean
to numeric type to align with the feature detection.
Change-Id: I53d3bc8dc2f6eac63feef22dfd627f3a48480afc
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
This change adds "FEAT_BRBE" to be part of feature detection mechanism.
Previously feature enablement flags were of boolean type, possessing
either 0 or 1. With the introduction of feature detection procedure
we now support three states for feature enablement build flags(0 to 2).
Accordingly, "ENABLE_BRBE_FOR_NS" flag is now modified from boolean
to numeric type to align with the feature detection.
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: I1eb52863b4afb10b808e2f0b6584a8a210d0f38c
The current implementation uses plat_arm API under generic code.
"plat_arm" API is a convention used with Arm common platform layer
and is reserved for that purpose. In addition, the function has a
weak definition which is not encouraged in TF-A.
Henceforth, removing the weak API with a configurable macro "TWED_DELAY"
of numeric data type in generic code and simplifying the implementation.
By default "TWED_DELAY" is defined to zero, and the delay value need to
be explicitly set by the platforms during buildtime.
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: I25cd6f628e863dc40415ced3a82d0662fdf2d75a
This patch adds architectural features detection procedure to ensure
features enabled are present in the given hardware implementation.
It verifies whether the architecture build flags passed during
compilation match the respective features by reading their ID
registers. It reads through all the enabled feature specific ID
registers at once and panics in case of mismatch(feature enabled
but not implemented in PE).
Feature flags are used at sections (context_management,
save and restore routines of registers) during context switch.
If the enabled feature flag is not supported by the PE, it causes an
exception while saving or restoring the registers guarded by them.
With this mechanism, the build flags are validated at an early
phase prior to their usage, thereby preventing any undefined action
under their control.
This implementation is based on tristate approach for each feature and
currently FEAT_STATE=0 and FEAT_STATE=1 are covered as part of this
patch. FEAT_STATE=2 is planned for phase-2 implementation and will be
taken care separately.
The patch has been explicitly tested, by adding a new test_config
with build config enabling majority of the features and detected
all of them under FVP launched with parameters enabling v8.7 features.
Note: This is an experimental procedure and the mechanism itself is
guarded by a macro "FEATURE_DETECTION", which is currently being
disabled by default.
The "FEATURE_DETECTION" macro is documented and the platforms are
encouraged to make use of this diagnostic tool by enabling this
"FEATURE_DETECTION" flag explicitly and get used to its behaviour
during booting before the procedure gets mandated.
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: Ia23d95430fe82d417a938b672bfb5edc401b0f43
Andre Przywara
Maksims Svecovs
Boyan Karatotev
Manish Pandey
Jayanth Dodderi Chidanand
Mark Brown
Juan Pablo Conde