This corrects the MISRA violation C2012-15.6:
The body of an iteration-statement or a selection-statement shall
be a compound-statement.
Enclosed statement body within the curly braces.
Change-Id: I14a69f79aba98e243fa29a50914431358efa2a49
Signed-off-by: Nithin G <nithing@amd.com>
Signed-off-by: Maheedhar Bollapalli <maheedharsai.bollapalli@amd.com>
SVE and SME aren't enabled symmetrically for all worlds, but EL3 needs
to context switch them nonetheless. Previously, this had to happen by
writing the enable bits just before reading/writing the relevant
context. But since the introduction of root context, this need not be
the case. We can have these enables always be present for EL3 and save
on some work (and ISBs!) on every context switch.
We can also hoist ZCR_EL3 to a never changing register, as we set its
value to be identical for every world, which happens to be the one we
want for EL3 too.
Change-Id: I3d950e72049a298008205ba32f230d5a5c02f8b0
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
The current code is incredibly resilient to updates to the spec and
has worked quite well so far. However, recent implementations expose a
weakness in that this is rather slow. A large part of it is written in
assembly, making it opaque to the compiler for optimisations. The
future proofness requires reading registers that are effectively
`volatile`, making it even harder for the compiler, as well as adding
lots of implicit barriers, making it hard for the microarchitecutre to
optimise as well.
We can make a few assumptions, checked by a few well placed asserts, and
remove a lot of this burden. For a start, at the moment there are 4
group 0 counters with static assignments. Contexting them is a trivial
affair that doesn't need a loop. Similarly, there can only be up to 16
group 1 counters. Contexting them is a bit harder, but we can do with a
single branch with a falling through switch. If/when both of these
change, we have a pair of asserts and the feature detection mechanism to
guard us against pretending that we support something we don't.
We can drop contexting of the offset registers. They are fully
accessible by EL2 and as such are its responsibility to preserve on
powerdown.
Another small thing we can do, is pass the core_pos into the hook.
The caller already knows which core we're running on, we don't need to
call this non-trivial function again.
Finally, knowing this, we don't really need the auxiliary AMUs to be
described by the device tree. Linux doesn't care at the moment, and any
information we need for EL3 can be neatly placed in a simple array.
All of this, combined with lifting the actual saving out of assembly,
reduces the instructions to save the context from 180 to 40, including a
lot fewer branches. The code is also much shorter and easier to read.
Also propagate to aarch32 so that the two don't diverge too much.
Change-Id: Ib62e6e9ba5be7fb9fb8965c8eee148d5598a5361
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Currently BRBE is being disabled for Realm world in EL3 by
switching the SBRBE bit in mdcr_el3 register to 0b00.
The patch removes the switching of SBRBE bits, and adds
context switch of BRBCR_EL2 register.
Change-Id: I66ca13edefc37e40fa265fd438b0b66f7d09b4bb
Signed-off-by: Sona Mathew <sonarebecca.mathew@arm.com>
Enable FEAT_FGT2 and FEAT_Debugv8p9 in Realm state as well.
Change-Id: Ib9cdde3af328ffdd8718b1ba404265757f2e542b
Signed-off-by: Sona Mathew <sonarebecca.mathew@arm.com>
When ICH_VMCR_EL2.VBPR1 is written in Secure state (SCR_EL3.NS==0)
and then subsequently read in Non-secure state (SCR_EL3.NS==1), a
wrong value might be returned. The same issue exists in the opposite way.
Adding workaround in EL3 software that performs context save/restore
on a change of Security state to use a value of SCR_EL3.NS when
accessing ICH_VMCR_EL2 that reflects the Security state that owns the
data being saved or restored. For example, EL3 software should set
SCR_EL3.NS to 1 when saving or restoring the value ICH_VMCR_EL2 for
Non-secure(or Realm) state. EL3 software should clear
SCR_EL3.NS to 0 when saving or restoring the value ICH_VMCR_EL2 for
Secure state.
SDEN documentation:
https://developer.arm.com/documentation/SDEN-1775101/latest/
Change-Id: I9f0403601c6346276e925f02eab55908b009d957
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
MDCR_EL3 register will context switch across all worlds. Thus the pmuv3
init has to be part of context management initialization.
Change-Id: I10ef7a3071c0fc5c11a93d3c9c2a95ec8c6493bf
Signed-off-by: Mateusz Sulimowicz <matsul@google.com>
FEAT_MOPS, mandatory from Arm v8.8, is typically managed in EL2.
However, in configurations where NS_EL2 is not enabled,
EL3 must set the HCRX_EL2.MSCEn bit to 1 to enable the feature.
This patch ensures FEAT_MOPS is enabled by setting HCRX_EL2.MSCEn to 1.
Change-Id: Ic4960e0cc14a44279156b79ded50de475b3b21c5
Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>
In preparation for SMCCC_ARCH_FEATURE_AVAILABILITY, it is useful for
context to be directly related to the underlying system. Currently,
certain bits like SCR_EL3.APK are always set with the understanding that
they will only take effect if the feature is present.
However, that is problematic for SMCCC_ARCH_FEATURE_AVAILABILITY (an
SMCCC call to report which features firmware enables), as simply reading
the enable bit may contradict the ID register, like the APK bit above
for a system with no Pauth present.
This patch is to clean up these cases. Add a check for PAuth's presence
so that the APK bit remains unset if not present. Also move SPE and TRBE
enablement to only the NS context. They already only enable the features
for NS only and disable them for Secure and Realm worlds. This change
only makes these worlds' context read 0 for easy bitmasking.
There's only a single snag on SPE and TRBE. Currently, their fields have
the same values and any world asymmetry is handled by hardware. Since we
don't want to do that, the buffers' ownership will change if we just set
the fields to 0 for non-NS worlds. Doing that, however, exposes Secure
state to a potential denial of service attack - a malicious NS can
enable profiling and call an SMC. Then, the owning security state will
change and since no SPE/TRBE registers are contexted, Secure state will
start generating records. Always have NS world own the buffers to
prevent this.
Finally, get rid of manage_extensions_common() as it's just a level of
indirection to enable a single feature.
Change-Id: I487bd4c70ac3e2105583917a0e5499e0ee248ed9
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
This patch fixes a bug which was introduced in commit
3065513 related to improper saving of EL1 context in the
context management library code when using 128-bit
system registers.
Bug explanation:
The function el1_sysregs_context_save still used the normal
macros that read all the system registers related to the EL1
context, which then involved casting them to uint64_t and
eventually writing them to a memory structure. This means that
the context management library was saving EL1-related SYSREG128
registers with the upper 64 bits zeroed out.
Alternative macros had previously been introduced for the EL2
context in the aforementioned commit, but not for EL1.
Some refactoring has also been done as part of this patch:
- Re-added "common" back to write_el2_ctx_common_sysreg128
- Added dummy SYSREG128 macros for cases when some features
are disabled
- Removed some newlines
Change-Id: I15aa2190794ac099a493e5f430220b1c81e1b558
Signed-off-by: Igor Podgainõi <igor.podgainoi@arm.com>
This patch enables support of FEAT_FPMR by enabling access
to FPMR register. It achieves it by setting the EnFPM bit of
SCR_EL3. This feature is currently enabled for NS world only.
Reference:
https://developer.arm.com/documentation/109697/2024_09/
Feature-descriptions/The-Armv9-5-architecture-extension?lang=en
Change-Id: I580c409b9b22f8ead0737502280fb9093a3d5dd2
Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>
Armv8.6 introduced the FEAT_LS64 extension, which provides a 64 *byte*
store instruction. A related instruction is ST64BV0, which will replace
the lowest 32 bits of the data with a value taken from the ACCDATA_EL1
system register (so that EL0 cannot alter them).
Using that ST64BV0 instruction and accessing the ACCDATA_EL1 system
register is guarded by two SCR_EL3 bits, which we should set to avoid a
trap into EL3, when lower ELs use one of those.
Add the required bits and pieces to make this feature usable:
- Add the ENABLE_FEAT_LS64_ACCDATA build option (defaulting to 0).
- Add the CPUID and SCR_EL3 bit definitions associated with FEAT_LS64.
- Add a feature check to check for the existing four variants of the
LS64 feature and detect future extensions.
- Add code to save and restore the ACCDATA_EL1 register on
secure/non-secure context switches.
- Enable the feature with runtime detection for FVP and Arm FPGA.
Please note that the *basic* FEAT_LS64 feature does not feature any trap
bits, it's only the addition of the ACCDATA_EL1 system register that
adds these traps and the SCR_EL3 bits.
Change-Id: Ie3e2ca2d9c4fbbd45c0cc6089accbb825579138a
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
This patch disables trapping to EL3 when the FEAT_D128
specific registers are accessed by setting the SCR_EL3.D128En bit.
If FEAT_D128 is implemented, then FEAT_SYSREG128 is implemented.
With FEAT_SYSREG128 certain system registers are treated as 128-bit,
so we should be context saving and restoring 128-bits instead of 64-bit
when FEAT_D128 is enabled.
FEAT_SYSREG128 adds support for MRRS and MSRR instruction which
helps us to read write to 128-bit system register.
Refer to Arm Architecture Manual for further details.
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.
Change-Id: I1a53db5eac29e56c8fbdcd4961ede3abfcb2411a
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
It used to be the case that a FEAT_RME build could not be built with
FEAT_BRBE support. BRBE doesn't have a 3-world aware disable and
MDCR_EL3 was not context switched to allow for disabling in Realm world.
As of commit 123002f917 MDCR_EL3 is
context switched. Since the flag for BRBE support is
ENABLE_BRBE_FOR_NS, move brbe_enable() to only happen for NS world. The
other worlds will see BRBE disabled and branch recording prohibited.
This allows for a build with both RME and BRBE.
Note that EL2 BRBE registers are not context switched. Further work is
needed if non-NS support is required.
Change-Id: I82f0f08399dcd080902477dc9636bc4541685f89
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Arm v8.9 introduces FEAT_SCTLR2, adding SCTLR2_ELx registers.
Support this, context switching the registers 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.
Change-Id: I0c4cba86917b6b065a7e8dd6af7daf64ee18dcda
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
Arm v8.9 introduces FEAT_THE, adding Translation Hardening Extension
Read-Check-Write mask registers, RCWMASK_EL1 and RCWSMASK_EL1.
Support this, context switching the registers 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.
Change-Id: I8775787f523639b39faf61d046ef482f73b2a562
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
Apply the mitigation only for the revision and variant
mentioned in the SDEN.
SDEN Documentation:
https://developer.arm.com/documentation/SDEN859515/latest
Change-Id: Ifda1f4cb32bdec9a9af29397ddc03bf22a7a87fc
Signed-off-by: Sona Mathew <sonarebecca.mathew@arm.com>
With introduction of FEAT_STATE_CHECK_ASYMMETRIC, the asymmetry of cores
can be handled. FEAT_TCR2 is one of the features which can be
asymmetric across cores and the respective support is added here.
Adding a function to handle this asymmetry by re-visting the
feature presence on running core.
There are two possible cases:
- If the primary core has the feature and secondary does not have it
then the feature is disabled.
- If the primary does not have the feature and secondary has it then,
the feature need to be enabled in secondary cores.
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: I73a70891d52268ddfa4effe40edf04115f5821ca
* Currently, EL1 context is included in cpu_context_t by default
for all the build configurations.
As part of the cpu context structure, we hold a copy of EL1, EL2
system registers, per world per PE. This context structure is
enormous and will continue to grow bigger with the addition of
new features incorporating new registers.
* Ideally, EL3 should save and restore the system registers at its next
lower exception level, which is EL2 in majority of the configurations.
* This patch aims at optimising the memory allocation in cases, when
the members from the context structure are unused. So el1 system
register context must be omitted when lower EL is always x-EL2.
* "CTX_INCLUDE_EL2_REGS" is the internal build flag which gets set,
when SPD=spmd and SPMD_SPM_AT_SEL2=1 or ENABLE_RME=1.
It indicates, the system registers at EL2 are context switched for
the respective build configuration. Here, there is no need to save
and restore EL1 system registers, while x-EL2 is enabled.
Henceforth, this patch addresses this issue, by taking out the EL1
context at all possible places, while EL2 (CTX_INCLUDE_EL2_REGS) is
enabled, there by saving memory.
Change-Id: Ifddc497d3c810e22a15b1c227a731bcc133c2f4a
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
SCTLR_EL1 and TCR_EL1 regs are included either as part of errata
"ERRATA_SPECULATIVE_AT" or under el1_sysregs_t context structure.
The code to write and read into these context entries, looks
repetitive and is invoked at most places.
This section is refactored to bring them under a static procedure,
keeping the code neat and easier to maintain.
Change-Id: Ib0d8c51bee09e1600c5baaa7f9745083dca9fee1
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
This patch checks if the Errata 2938996(Cortex-A520) , 2726228(Cortex-X4)
applies to cores and if affected applies the errata workaround which
disables TRBE.
Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>
Change-Id: I53b037839820c8b3a869f393588302a365d5b97c
With introduction of FEAT_STATE_CHECK_ASYMMETRIC, the asymmetry of cores
can be handled. SPE is one of the features which can be asymmetric
across cores.
Add a function to handle this asymmetry by re-visting the feature
presence on running core.
There are two possible cases:
- If the primary has the feature and secondary does not have it then,
the feature needs to be disabled.
- If the primary does not have the feature and secondary has it then,
the feature need to be enabled
Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: Ibb2b88b5ef63b3efcb80801898ae8d8967e5c271
TF-A assumes that all the cores in a platform has architecture feature
parity, this is evident by the fact that primary sets up the
Non-secure context of secondary cores.
With changing landscape of platforms (e.g. big/little/mid cores), we are
seeing more and more platforms which has feature asymmetry among cores.
There is also a scenario where certain CPU erratum only applies to one
type of cores and requires a feature to be disabled even it supports
the feature.
To handle these scenarios, introduce a hook in warmboot path which would
be called on the running CPU to override any feature disparity in the
NS context stashed up by primary. Note that, re-checking of feature for
Secure/Realm context is not required as the context is created on
running core itself.
Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: I5a01dbda528fa8481a00fdd098b58a7463ed0e22
Currently the EL1 part of the context structure (el1_sysregs_t),
is coupled with feature flags reducing the context memory allocation
for platforms, that don't enable/support all the architectural
features at once.
Similar to the el2 context optimization commit-"d6af234" this patch
further improves this section by converting the assembly context-offset
entries into a c structure. It relies on garbage collection of the
linker removing unreferenced structures from memory, as well as aiding
in readability and future maintenance. Additionally, it eliminates
the #ifs usage in 'context_mgmt.c' source file.
Change-Id: If6075931cec994bc89231241337eccc7042c5ede
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
* Currently, "ERRATA_SPECUALTIVE_AT" errata is enabled by default
for few cores and they need context entries for saving and
restoring EL1 regs "SCTLR_EL1 and TCR_EL1" registers at all times.
* This prevents the mechanism of decoupling EL1 and EL2 registers,
as EL3 firmware shouldn't be handling both simultaneously.
* Depending on the build configuration either EL1 or EL2 context
structures need to included, which would result in saving a good
amount of context memory.
* In order to achieve this it's essential to have explicit context
entries for registers supporting "ERRATA_SPECULATIVE_AT".
* This patch adds two context entries under "errata_speculative_at"
structure to assist this errata and thereby allows decoupling
EL1 and EL2 context structures.
Change-Id: Ia50626eea8fb64899a2e2d81622adbe07fe77d65
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
The system register actlr_el2 can be set during CPU or platform reset
handler. E.g. on Arm Total Compute platform, the CLUSTERPMUEN bit of
actlr_el2 is set in the platform reset handler to enable the write
access to DSU PMU registers from EL1. However, as EL2 context gets
restored without saving it beforehand during jump to SPM and next NS
image, therefore, the initialized value of actlr_el2 is not retained.
To fix this issue, keep track of actlr_el2 value during the EL2 context
initialization. This applies for both secure and non-secure security
state.
Change-Id: I1bd7b984216c042c056ad20c6724bedce5a6a3e2
Signed-off-by: Jagdish Gediya <jagdish.gediya@arm.com>
Signed-off-by: Leo Yan <leo.yan@arm.com>
This patch disables trapping to EL3 when the FEAT_FGT2
specific trap registers are accessed by setting the
SCR_EL3.FGTEn2 bit
Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>
Change-Id: I6d2b614affb9067b2bc3d7bf0ae7d169d031592a
This patch enables FEAT_Debugv8p9 and prevents EL1/0 from
trapping to EL3 when accessing MDSELR_EL1 register by
setting the MDCR_EL3.EBWE bit.
Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>
Change-Id: I3613af1dd8cb8c0d3c33dc959f170846c0b9695a
Currently MDCR_EL3 register value is same for all the
worlds(Non-secure, Secure, Realm and Root).
With this approach, features enable/disable settings
remain same across all the worlds. This is not ideal as
there must be flexibility in controlling feature as per
the requirements for individual world.
The patch addresses this by providing MDCR_EL3 a per world
value. Features with identical values for all the worlds are
grouped under ``manage_extensions_common`` API.
Change-Id: Ibc068d985fe165d8cb6d0ffb84119bffd743b3d1
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Currently, during the initial bootup phase SCTLR_EL2 register
has been initialised with the endianness bit based on header
attribute evaluation at EL3.
This is not mandatorily required as TF-A by default, expects
the software at EL2 to execute in little endian format ( EE = 0).
Henceforth, this patch removes the endianness bit evaluation for
SCTLR_EL2 register and initialises with a predefined RESET value,
setting SCTLR_EL2.EE=0.
Change-Id: I53fdd5bf907cbe35c551fc03cc893821229ff807
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
* FEAT_MPAM related EL2 registers are placed explicitly outside
the EL2 context in the cpu_context_t structure.
* With EL2 registers now coupled with dependent features, this
patch moves them to the el2_context structure "el2_sysregs_t".
* Further, converting the assembly context-offset entries into a
c structure. It relies on garbage collection of the linker
removing unreferenced structures from memory, as well as aiding
in readability and future maintenance.
Change-Id: Ib784bc8d2fbe35a8a47a569426d8663282ec06aa
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
The following system registers are made part of save and restore
operations for EL1 context:
TRFCR_EL1
SCXTNUM_EL0
SCXTNUM_EL1
GCSCR_EL1
GCSCRE0_EL1
GCSPR_EL1
GCSPR_EL0
Change-Id: I1077112bdc29a6c9cd39b9707d6cf10b95fa15e3
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
* changes:
fix(bl1): add missing `__RW_{START,END}__` symbols
fix(fvp): don't check MPIDRs with the power controller in BL1
fix(arm): only expose `arm_bl2_dyn_cfg_init` to BL2
fix(cm): hide `cm_init_context_by_index` from BL1
fix(bl1): add missing spinlock dependency
commit@c282384dbb45b6185b4aba14efebbad110d18e49
removed ENABLE_FEAT_MTE but missed its usage in
context structure declaration path.
All mte regs that are currently context saved/restored
are needed only when FEAT_MTE2 is enabled, so move to
usage of FEAT_MTE2 and remove FEAT_MTE usage
Change-Id: I6b4417485fa6b7f52a31045562600945e48e81b7
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
BL1 requires the context management library but does not use or
implement `cm_init_context_by_index`. This change ensures that is not
compiled into BL1, as linking with LTO enabled causes an undefined
reference for this function.
Change-Id: I4a4602843bd75bc4f47b3e0c4c5a6efce1514ef6
Signed-off-by: Chris Kay <chris.kay@arm.com>
The following system registers are made part of save and restore
operations for EL1 context:
MDCCINT_EL1
MDSCR_EL1
DISR_EL1
PIRE0_EL1
PIR_EL1
POR_EL1
S2POR_EL1
TCR2_EL1
Some of these registers are available as part of core Armv8-A
architecture while others are made available through various
architectural extensions.
Change-Id: I507dccb9053ba177e1b98100fceccd1f32bdfc5c
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
This patch fixes a typo which led to incorrect context save
operations for two FEAT_GCS registers.
Change-Id: I3d3202a6721714bbc8f84c2d775d1b28afffa5df
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Currently both FEAT_MTE and FEAT_MTE_PERM aren't used for enabling
of any feature bits in EL3. So remove both FEAT handling.
All mte regs that are currently context saved/restored are needed
only when FEAT_MTE2 is enabled, so move to usage of FEAT_MTE2 and
remove FEAT_MTE usage.
BREAKING CHANGE: Any platform or downstream code trying to use
SCR_EL3.ATA bit(26) will see failures as this is now moved to be
used only with FEAT_MTE2 with
commit@ef0d0e5478a3f19cbe70a378b9b184036db38fe2
Change-Id: Id01e154156571f7792135639e17dc5c8d0e17cf8
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
This patch covers the following:
* Conditions set for verifying the EL2 presence and its usage
for various scenarios while exiting to Non secure world
"cm_prepare_el3_exit" has been improved.
* It thereby also fixes the issue(misra_c_2012_rule_15_7_violation)
for not terminating "if..else if" construct with an else statement
and keeps code in accordance with MISRA standards.
Change-Id: Ie5284447f5ac91412552629b76dbf2e636a09fd9
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Currently the EL2 part of the context structure (el2_sysregs_t), is
mostly feature dependent.
For instance, CTX_HCRX_EL2 is only needed when FEAT_HCX
(ENABLE_FEAT_HCX=1) is set, but the entry is unconditionally added
in the EL2 context structure and thereby consuming memory even in
build configurations where FEAT_HCX is disabled.
Henceforth, all such context entries should be coupled/tied with
their respective feature enables and be optimized away when unused.
This would reduce the context memory allocation for platforms, that
dont enable/support all the architectural features at once.
Further, converting the assembly context-offset entries into
a c structure relies on garbage collection of the linker
removing unreferenced structures from memory, as well as aiding
in readability and future maintenance.
Change-Id: I0cf49498ee3033cb6f3ee3810331121b26627783
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
