arch-arm: PSTATE.PAN changes should inval cached regs in TLB

Change-Id: Id94e355fec345d2e952539a7dce7fbd21ed220c6
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20983
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch-arm: Fix read/setMiscReg for AArch32 GICv3 ICC regs

The readMiscReg/setMiscReg methods were not forwarding register
reads/writes to the cpu interface when in AArch32.

Change-Id: Ide983e793b8033a88d31fe6ea87eaeffe9b093f5
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20611
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: adding register control flags enabling LSE implementation

Added changes on arch-arm architecture to accept Atomic instructions
following ARM v8.1 documentation. That includes enabling atomic bit
in ID registers and add have_lse variable into arm system.

Change-Id: Ic28d3215d74ff129142fb51cb2fa217d3b1482de
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19809
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch-arm: Implement ARMv8.1-PAN, Privileged access never

ARMv8.1-PAN adds a new bit to PSTATE. When the value of this PAN state
bit is 1, any privileged data access from EL1 or EL2 to a virtual memory
address that is accessible at EL0 generates a Permission fault.
This feature is mandatory in ARMv8.1 implementations.
This feature is supported in AArch64 and AArch32 states.
The ID_AA64MMFR1_EL1.PAN, ID_MMFR3_EL1.PAN, and ID_MMFR3.PAN fields
identify the support for ARMv8.1-PAN.

Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Change-Id: I94a76311711739dd2394c72944d88ba9321fd159
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19729
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch-arm: Expose haveGicv3CPUInterface to the ISA interface

Change-Id: I36232b7618ad875983f34b741c51f12ddb9ae166
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17989
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch-arm: Remove un-needed hyp flag in TLBI operations

The hyp flag was probably a legacy pre-v8 flag distinguishing
invalidation targeting PL2 translation regime (hyp mode).
Since the introduction of target_el parameter, hyp boolean is not needed
anymore. The patch works by setting the hyp flag in the flush* methods
in the TLB automatically by checking if target_el == EL2.

Change-Id: I798009e09ff24a383dea871e348188bae2685e8e
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Jan-Peter Larsson <jan-peter.larsson@arm.com>
Reviewed-by: Anouk Van Laer <anouk.vanlaer@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18389
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch-arm: Correct target EL field in TLBI operations

Some TLB Invalidation operations affecting the EL2 translation regime
were marked as targeting EL1 instead of EL2

Change-Id: I77821eec7a409e9df6a6814855f9a375832ffe74
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Jan-Peter Larsson <jan-peter.larsson@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18388
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

dev-arm: Make GICv3 maintenance interrupt an ArmInterrupt

Change-Id: I88e2b72849cdf3f69026c62517303837e7d3d551
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Anouk Van Laer <anouk.vanlaer@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17629
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm,cpu: Add initial support for Arm SVE

This changeset adds initial support for the Arm Scalable Vector Extension
(SVE) by implementing:
- support for most data-processing instructions (no loads/stores yet);
- basic system-level support.

Additional authors:
- Javier Setoain <javier.setoain@arm.com>
- Gabor Dozsa <gabor.dozsa@arm.com>
- Giacomo Travaglini <giacomo.travaglini@arm.com>

Thanks to Pau Cabre for his contribution of bugfixes.

Change-Id: I1808b5ff55b401777eeb9b99c9a1129e0d527709
Signed-off-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/13515
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Move GICv3 detection at startup time

At the moment the haveGicV3 parameter is used only to signal its
presence when reading the MISCREG_ID_AA64PFR0_EL1 register. It depends
on the system->getGIC pointing to a GICv3 model. However this pointer
is set in the System only at init time (after construction), which means
that the haveGICv3CPUInterface will always be false.
This patch is fixing this by moving the parameter initialization at
startup time, together with the cpu interface registration.

Change-Id: I8da6711ea741ecd0f78ec8ca60a8c3ae3bca2421
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Anouk Van Laer <anouk.vanlaer@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/16483
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Inital vector rename mode depending on A32/A64

Change-Id: I6b99833641b0ab6534471d5ff3ca5d3791285481
Reviewed-on: https://gem5-review.googlesource.com/c/15599
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch: cpu: Stop passing around misc registers by reference.

These values are all basic integers (specifically uint64_t now), and
so passing them by const & is actually less efficient since there's a
extra level of indirection and an extra value, and the same sized value
(a 64 bit pointer vs. a 64 bit int) is being passed around.

Change-Id: Ie9956b8dc4c225068ab1afaba233ec2b42b76da3
Reviewed-on: https://gem5-review.googlesource.com/c/13626
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

arm: Get rid of some register type definitions.

These are IntReg, FloatReg, FloatRegBits, and MiscReg. These have been
supplanted by the global types RegVal and FloatRegVal.

Change-Id: Ief1cd85d0eff7156282ddb1ce168a2a5677f7435
Reviewed-on: https://gem5-review.googlesource.com/c/13625
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>

arch-arm: Read VMPIDR instead of MPIDR when EL2 is Enabled

Trying to read MPIDR(_EL1) from EL1, should return the value of
VMPIDR_EL2 if EL2 is enabled. This patch is modifying the utility
function for reading MPIDR in order to match this behaviour for both
AArch32 and AArch64.

Change-Id: I32c2d4d5052f509e6e0542a5314844164221c6a3
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/15617
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Added TLBI_ALL EL2 instruction

This patch is adding TLBI_ALLE2(IS) operations to the arm ISA.

Change-Id: I8e35cff9a2cc414f4c5fbbc5aa0cfe5023a3f011
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Anouk Van Laer <anouk.vanlaer@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/15616
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

dev-arm: Add a GICv3 model

Change-Id: Ib0067fc743f84ff7be9f12d2fc33ddf63736bdd1
Reviewed-on: https://gem5-review.googlesource.com/c/13436
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>

arm: properly handle RES0/1 for SCTLRs

They were being treated as RAZ/RAO, which is incorrect.
Put the access masks in the register metadatabase now that we have one.

Also fix this for HVBAR.

Change-Id: I097c847e35be2d59fb8235fc621bb061ef514cfb
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/10401
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Add Crypto in SE mode

This patch is also enabling AArch32 crypto instructions by setting the
ID_ISAR5 register accordingly.

Change-Id: Id412585b39b78570a65bd3047199c84e9db76cda
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/15155
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Print register name when warning on AT instructions

With this patch we don't print anymore the enum value when warning
on any AT instruction usage, but we print the sys reg name instead

Change-Id: Ic6831b98ad6b0582be69883dc9519a9d3324da30
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Anouk Van Laer <anouk.vanlaer@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/14316
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: ArmSystem::resetAddr64 renamed to be used in AArch32

ARMv8 differs from ARMv7 with the presence of RVBAR register, which
contains the implementation defined reset address when EL3 is not
implemented.
The entry 0x0 in the AArch32 vector table, once used for the Reset
Vector, is now marked as "Not used", stating that it is now IMPLEMENTATION
DEFINED. An implementation might still use this vector table entry to
hold the Reset vector, but having a Reset address != than the general
vector table (for any other exception) is allowed.

At the moment any Reset exception is still using 0 as a vector table
base address. This patch is extending the ArmSystem::resetAddr64 to
ArmSystem::resetAddr so that it can be used for initializing
MVBAR/RVBAR. In order to do so, we are providing a specialized behavior
for the Reset exception when evaluating the vector base address.

Change-Id: I051a730dc089e194db3b107bbed19251c661f87e
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/14000
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Refactor ISA::clear by adding a ISA::clear32 method

The patch is also moving some initialization code to be used
by AArch64 as well since the registers are mapped to AArch64 ones.

Change-Id: I0089df25275434172c6e0e9cb125ee535c04d1b8
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/13997
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Add have_crypto System parameter

This patch adds the have_crypto ArmSystem parameter for enabling crypto
extension. This is done by modifying the AArch32/AArch64 ID registers
at startup time.

Change-Id: I6eefb7e6f6354802a14ea639ad53b75f8e1e11c5
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/13252
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

arch-arm: Implement AArch64 ID_AA64MMFR2_EL1 register

This patch implements AArch64 Memory Model Feature Register 2
(from ARMv8.2)

Change-Id: I16d9acaf620fac6d1206e208bd143daec1657daf
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/13066
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Init AArch64 ID registers in SE mode

One of the auxv vector's flag is the HWCAP, whose bits match the content
of several arm ID registers. This patch factors out AArch64 ID
registers init into a separate method and creates the symmetric AArch32
ID register init as well, so that we get a meaningful auxiliary vector
in SE mode.

Change-Id: I52bdb31b67508c4447558ebd7ca743733a69280e
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/13064
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arm: Add support for tracking TCs in ISA devices

ISA devices typically need to keep track of the thread context they
are associated with. Among other things, this is required for
interrupt delivery. Add a BaseISADevice:setThreadContext() method to
wire such models to the right thread context.

Change-Id: Iad354d176c0c4c4e34c6ab8b5acaee0b69da0406
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/12399
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>

arch-arm: Introduce ARMv8.1 Virtual Timer System Registers

Adding CNTHV_CTL_EL2, CNTHV_CVAL_EL2, CNTHV_TVAL_EL2 System Registers
into the decode tree. They are currently implemented as a generic timer
and produces a warning if accessed.

Change-Id: I1a23035d67f95eeac49d890283e9a0d58426d504
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/11592
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Add Illegal Execution flag to PCState

This patch moves the detection of the Illegal Execution flag (PSTATE.IL)
from the tlb translation stage (fetch) to the decoding stage. This is
done by adding the illegalExecution field to the PCState.

Change-Id: I9c1c4e9c6bd5ded905c1d56b3034e4e9322582fa
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10813
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

misc: Using smart pointers for memory Requests

This patch is changing the underlying type for RequestPtr from Request*
to shared_ptr<Request>. Having memory requests being managed by smart
pointers will simplify the code; it will also prevent memory leakage and
dangling pointers.

Change-Id: I7749af38a11ac8eb4d53d8df1252951e0890fde3
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10996
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

arch-arm: ISA param for treating MISCREG_IMPDEF_UNIMPL as NOP

In the Arm ISA there are some sys reg numbers which are reserved for
implementation defined registers. The default behaviour is to to treat
them as unimplemented registers. It is now possible to change this
behaviour at runtime and treat them as NOP. In this way an access to
those register won't make simulation fail.

Change-Id: I0d108299a6d5aa81fcdabdaef04eafe46df92343
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10504
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Map ID_x_EL1 registers to AArch32 version

AArch64 ID_x_EL1 registers map to AArch32 ID_x counterparts. Those
registers must be initialized even when the highest Exception Level is
using AArch64.

Change-Id: Iccc9b6f631f5fac288116eb1ef2ad1d30c03de7b
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10361
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Add ARMv8.1 TTBR1_EL2 register

This patch adds ARMv8.1 TTBR1_EL2 register into the decodeAArch64SysReg
table, but stil leaving it unimplemented (Accessing it through MSR/MRS
causes an exception)

Change-Id: I463b86cc544233aa1ee5b2fcba689d6b9f2a874b
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10063
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Fix masking in CPACR_EL1

Some bits in CPACR_EL1 are RES0 but not RAZ/WI. For instance, bit
CPACR_EL1[31] is RES0 but should be made stateful, since it allows
programing of CPACR.ASEDIS. Therefore the masking of CPACR_EL1
is removed.

Change-Id: If1fa3fa1e06bc38495b8afce2c635f3ddf76ce32
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10046
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Mask out unsupported trapped exception handling bits

Floating-point trapped exception handlings are not currently
supported in gem5, therefore the corresponding bits are RAZ/WI in
FCPR.

Change-Id: Ica43af62d5f3bbc095e8dd872f0bd365231a5b5f
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10045
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Correct masking of cp10 and cp11 in CPACR

This patch fixes the masking of cp10 and cp11 in CPACR according to
NSACR.cp10 / NSACR.cp11 by adding the condition "in Non-secure state,
if EL3 is implemented and is using AArch32...", which is specified in
ARM ARM.

Change-Id: Id00e7bf04d6a985e27dbf1028677da0746b79924
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10044
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Using explicit invalidation in TLB

When setting TLB related MiscRegs, using explicit TLB regs invalidation
rather than implicit switch-case fallthrough

Change-Id: Ia1a7358b6d54dda3811be1c5ce5d676f8c518c4d
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10041
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Fix secure write of SCTLR when EL3 is AArch64

MiscRegisters are not banked between secure and non-secure mode if EL3
is not implemented or if EL3 is using AArch64 (highestELIs64). In this
scenario a unique register is used and it is mapped to the NS version
(see snsBankedIndex implementation), so that a secure world read/write
should access the non secure storage.

Change-Id: Ica4182e3cdf4021d2bd1db23e477ce2bbf055926
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/9502
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Distinguish IS TLBI from non-IS

TLBI broadcasting was the default implementation of most of TLBI
instructions. This patch applies the broadcasting behaviour only to the
Inner-Shareable subset, while simpler TLB invalidation instructions only
affect the PE that executes them.

Change-Id: Idb01d0d4f593131f657e8fc9668112de8e4ccdcb
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/9182
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Created function for TLB ASID Invalidation

This patch is intended to avoid code duplication and extends the set of
TLBI ISA functions adding the entry invalidation by ASID match.

Change-Id: I9bcb498059ea480dd2118639c7b3c64fea80a5e1
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/9181
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Adding IPA-Based Invalidating instructions

This patch introduces the TLB IPA-Based invalidating instructions in
aarch32. In the entry selection policy the level of translation is not
taken into account.
This means that no difference stands between (e.g.) TLBIIPAS2 and
TLBIPAS2L.

Change-Id: Ieeb54665480874d2041056f356d86448c45043cb
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8822
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Implement missing aarch32 TLBI registers

In the pool of TLB Invalidate system register a category of instruction
was missing: the ones operating on entries added to the TLB during the
last level only of a table walk. (E.g. TLBIVMAL). This patch is not
considering this matching criteria when invalidating the entries and it
is rather performing the invalidation on all levels.

Change-Id: I5f2186cfdd73793e76c90b260f7128be187903fe
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8821
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Fix FSC generation in AbortFault

The fault status code generated by a Prefetch/Data Fault was containing
a wrong value when the fault was triggered in aarch32 but handled in
aarch64. This because the encoding differs between the two ISAs and the
encoder was just checking the starting ISA rather than the the ending
one. In this case the getFsr must be called after we know which is the
ending ISA, which happens only after ArmFault::invoke gets called. The
fsc update hence happens before writing into the Syndrome register.

Change-Id: I725f12b6dcc0178f608233bd3d15e466d1cd1ffc
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8362
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Change ArmFault cast from reinterpret to static

Changing casting type in src/arch/arm/isa.cc

Change-Id: Ia19b30a1bf8b1b25df149b52613a3533eaced03a
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8241
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Don't change PSTATE in Illegal Exception return

This patch fixes the Illegal Exception return handler. According to the
armarm documentation, when PSTATE.IL is set to one because of an illegal
exception return, PSTATE.{EL, nRW, SP} are unchanged. This means the
Exception level, Execution state, and stack pointer selection do not
change as a result of the return.

Change-Id: I35f2fe68fb2822a54fc4a21930871eab7a1aaab4
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8021
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: understandably initialize register permissions

Move massive initialization routine to the bottom of miscregs.cc.
Additionally, share register metadata across ISA instances by
making lookUpMiscReg a static member of the ISA and only
initializing it once.

Change-Id: I6d6ab26200c4e781151cc6efd97ce2420e2bf4cc
Signed-off-by: Curtis Dunham <Curtis.Dunham@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jack Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/6803
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arm: extend MiscReg metadata structures

Implement proper handling of RES0/RES1 and RAZ/RAO bitfields.

Change-Id: I344c32c3fb1d142acfb0521ba3590ddd2b1f5360
Signed-off-by: Curtis Dunham <Curtis.Dunham@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jack Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/6802
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: understandably initialize register mappings

The mappings for sharing a backing store between AArch32
and AArch64 system registers are made clearer using an
initializer object.

Change-Id: I29dcfab2797b4d36b3182342997edffde334a291
Signed-off-by: Curtis Dunham <Curtis.Dunham@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jack Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/6801
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch,cpu: "virtualize" the TLB interface.

CPUs have historically instantiated the architecture specific version
of the TLBs to avoid a virtual function call, making them a little bit
more dependent on what the current ISA is. Some simple performance
measurement, the x86 twolf regression on the atomic CPU, shows that
there isn't actually any performance benefit, and if anything the
simulator goes slightly faster (although still within margin of error)
when the TLB functions are virtual.

This change switches everything outside of the architectures themselves
to use the generic BaseTLB type, and then inside the ISA for them to
cast that to their architecture specific type to call into architecture
specific interfaces.

The ARM TLB needed the most adjustment since it was using non-standard
translation function signatures. Specifically, they all took an extra
"type" parameter which defaulted to normal, and translateTiming
returned a Fault. translateTiming actually doesn't need to return a
Fault because everywhere that consumed it just stored it into a
structure which it then deleted(?), and the fault is stored in the
Translation object when the translation is done.

A little more work is needed to fully obviate the arch/tlb.hh header,
so the TheISA::TLB type is still visible outside of the ISAs.
Specifically, the TlbEntry type is used in the generic PageTable which
lives in src/mem.

Change-Id: I51b68ee74411f9af778317eff222f9349d2ed575
Reviewed-on: https://gem5-review.googlesource.com/6921
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

misc: Updates for gcc7.2 for x86

GCC 7.2 is much stricter than previous GCC versions. The following changes
are needed:

* There is now a warning if there is an implicit fallthrough between two
case statments. C++17 adds the [[fallthrough]]; declaration. However,
to support non C++17 standards (i.e., C++11), we use M5_FALLTHROUGH.
M5_FALLTHROUGH checks for [[fallthrough]] compliant C++17 compiler and
if that doesn't exist, it defaults to nothing (no older compilers
generate warnings).
* The above resulted in a couple of bugs that were found. This is noted
in the review request on gerrit.
* throw() for dynamic exception specification is deprecated
* There were a couple of new uninitialized variable warnings
* Can no longer perform bitwise operations on a bool.
* Must now include <functional> for std::function
* Compiler bug for void* lambda. Changed to auto as work around. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82878

Change-Id: I5d4c782a4e133fa4cdb119e35d9aff68c6e2958e
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/5802
Reviewed-by: Gabe Black <gabeblack@google.com>

cpu: Added interface for vector reg file

This patch adds some more functionality to the cpu model and the arch to
interface with the vector register file.

This change consists mainly of augmenting ThreadContexts and ExecContexts
with calls to get/set full vectors, underlying microarchitectural elements
or lanes. Those are meant to interface with the vector register file. All
classes that implement this interface also get an appropriate implementation.

This requires implementing the vector register file for the different
models using the VecRegContainer class.

This change set also updates the Result abstraction to contemplate the
possibility of having a vector as result.

The changes also affect how the remote_gdb connection works.

There are some (nasty) side effects, such as the need to define dummy
numPhysVecRegs parameter values for architectures that do not implement
vector extensions.

Nathanael Premillieu's work with an increasing number of fixes and
improvements of mine.

Change-Id: Iee65f4e8b03abfe1e94e6940a51b68d0977fd5bb
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
[ Fix RISCV build issues and CC reg free list initialisation ]
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2705

arm: AArch64 report cache size correctly when reading CTR_EL0

Trying to read MISCREG_CTR_EL0 on AArch64 returned 0 as is was not
implmemented. With that an operating system relying on the cache line
sizes reported in order to manage the caches would (a) panic given the
returned value 0 is not valid (high bit is RES1) or (b) worst case would
assume a cache line size of 4 doing a tremendous amount of extra
instruction work (including fetching). Return the same values as for ARMv7
as the fields seem to be the same, or RES0/1 seem to be reported
accordingly for AArch64

In collaboration with: Andrew Turner

Testing Done: Checked on FreeBSD boots with extra printfs; also observed a
reduction of a factor of about 10 in instruction fetches for a simple
micro-test.

Reviewed at http://reviews.gem5.org/r/3667/

Signed-off-by: Jason Lowe-Power <jason@lowepower.com>

style: [patch 1/22] use /r/3648/ to reorganize includes

arm: provide correct timer availability in ID_PFR1 register

Change-Id: Id4cd839c12b70616017a5830e3f9bbb59b0f97ba
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

arm: compute ID_AA64PFR{0,1}_EL1 registers

Compute the proper values of the aforementioned registers from
the system configuration rather than configuring the values themselves.

Change-Id: If9774b6610a29568b80ae4866107b9a6a5b5be0f
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

arm: compute ID_PFR{0,1} registers

Compute the proper values of the aforementioned registers from
the system configuration rather than configuring the values themselves.

Change-Id: Ie7685b5d8b5f2dd9d6380b4af74f16d596b2bfd1
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

arm: miscreg refactoring

Change-Id: I4e9e8f264a4a4239dd135a6c7a1c8da213b6d345
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

arm: audit SCTLR

Change-Id: I814f1431a5f754f75721c9ac51171f860a714d24
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

arm: remove SCTLR.FI

Removed from ARMARM.

Change-Id: Ie8f28e4fa6e1b46dfd9c8c4b379e5b42fe25421d
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

arm: update AArch{64,32} register mappings

Change-Id: Idaaaeb3f7b1a0bdbf18d8e2d46686c78bb411317
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

cpu, arch: fix the type used for the request flags

Change-Id: I183b9942929c873c3272ce6d1abd4ebc472c7132
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

arm: Add TLBI instruction for stage 2 IPA's

This patch adds support for stage 2 TLBI instructions
such as TLBI IPAS2E1_Xt.

Change-Id: I0cd5e8055b0c1003e03439aa5183252f50ea0a88

arm: Fix EL perceived at TLB for address translation instructions

During address translation instructions (such as AT S1E1R_Xt) the exception
level can be different than the current exception level. This patch fixes
how the TLB determines what EL to use during these instructions.

Change-Id: Ia9ce229404de9e284bc1f7479fd2c580efd55f8f

arm: add stage2 translation support

Change-Id: I8f7c09c7ec3a97149ebebf4b21471b244e6cecc1

arm: enable EL2 support

Change-Id: I59fa4fae98c33d9e5c2185382e1411911d27d341

arm: invalidate TLB miscreg cache on modification of HSCTLR

Change-Id: I5212c91c56435fe008950ed99feacc6921609226

arm: Don't consult the TLB test iface for functional translations

Don't consult the TLB test interface for PA's returned by functional
translations by the AT instruction. We implement this by chaning the
ISA code to synthesize 0-length functional reads for the TLB lookup.
The TLB then bypasses the final PA check in the tester if the size is
zero.

Change-Id: I2487b7f829cea88c37e229e9fc7a4543aced961b
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>

mem: Remove threadId from memory request class

In general, the ThreadID parameter is unnecessary in the memory system
as the ContextID is what is used for the purposes of locks/wakeups.
Since we allocate sequential ContextIDs for each thread on MT-enabled
CPUs, ThreadID is unnecessary as the CPUs can identify the requesting
thread through sideband info (SenderState / LSQ entries) or ContextID
offset from the base ContextID for a cpu.

This is a re-spin of 20264eb after the revert (bd1c6789) and includes
some fixes of that commit.

Revert power patch sets with unexpected interactions

The following patches had unexpected interactions with the current
upstream code and have been reverted for now:

e07fd01651f3: power: Add support for power models
831c7f2f9e39: power: Low-power idle power state for idle CPUs
4f749e00b667: power: Add power states to ClockedObject

Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>

mem: Remove threadId from memory request class

In general, the ThreadID parameter is unnecessary in the memory system
as the ContextID is what is used for the purposes of locks/wakeups.
Since we allocate sequential ContextIDs for each thread on MT-enabled
CPUs, ThreadID is unnecessary as the CPUs can identify the requesting
thread through sideband info (SenderState / LSQ entries) or ContextID
offset from the base ContextID for a cpu.

isa: Add parameter to pick different decoder inside ISA

The decoder is responsible for splitting instructions in micro
operations (uops). Given that different micro architectures may split
operations differently, this patch allows to specify which micro
architecture each isa implements, so different cores in the system can
split instructions differently, also decoupling uop splitting
(microArch) from ISA (Arch). This is done making the decodification
calls templates that receive a type 'DecoderFlavour' that maps the
name of the operation to the class that implements it. This way there
is only one selection point (converting the command line enum to the
appropriate DecodeFeatures object). In addition, there is no explicit
code replication: template instantiation hides that, and the compiler
should be able to resolve a number of things at compile-time.

isa,cpu: Add support for FS SMT Interrupts

Adds per-thread interrupt controllers and thread/context logic
so that interrupts properly get routed in SMT systems.

arm: Delete debug print in initialization of hardware thread

There seems to have been a debug print left in when the original ARMv8
support was merged in. This printout is performed every time you
initialize a hardware thread, and it prints raw pointers, so it always
causes diffs in the regression. This patch removes the debug print.

dev, arm: Refactor and clean up the generic timer model

This changeset cleans up the generic timer a bit and moves most of the
register juggling from the ISA code into a separate class in the same
source file as the rest of the generic timer. It also removes the
assumption that there is always 8 or fewer CPUs in the system. Instead
of having a fixed limit, we now instantiate per-core timers as they
are requested. This is all in preparation for other patches that add
support for virtual timers and a memory mapped interface.

arm: Remove unnecessary boot uncachability

With the recent patches addressing how we deal with uncacheable
accesses there is no longer need for the work arounds put in place to
enforce certain sections of memory to be uncacheable during boot.

arm: Don't truncate 16-bit ASIDs to 8 bits

The ISA code sometimes stores 16-bit ASIDs as 8-bit unsigned integers
and has a couple of inverted checks that mask out the high 8 bits of
an ASID if 16-bit ASIDs have been /enabled/. This changeset fixes both
of those issues.

mem: Clean up Request initialisation

This patch tidies up how we create and set the fields of a Request. In
essence it tries to use the constructor where possible (as opposed to
setPhys and setVirt), thus avoiding spreading the information across a
number of locations. In fact, setPhys is made private as part of this
patch, and a number of places where we callede setVirt instead uses
the appropriate constructor.

arm: Add support for filtering in the PMU

This patch adds support for filtering events in the PMU. In order to
do so, it updates the ISADevice base class to forward an ISA pointer
to ISA devices. This enables such devices to access the MiscReg file
to determine the current execution level.

arm: Fix multi-system AArch64 boot w/caches.

Automatically extract cpu release address from DTB file.
Check SCTLR_EL1 to verify all caches are enabled.

arm: Add a model of an ARM PMUv3

This class implements a subset of the ARM PMU v3 specification as
described in the ARMv8 reference manual. It supports most of the
features of the PMU, however the following features are known to be
missing:

* Event filtering (e.g., from different privilege levels).
* Access controls (the PMU currently ignores the execution level).
* The chain counter (event no. 0x1E) is unimplemented.

The PMU itself does not implement any events, it merely provides an
interface for the configuration scripts to hook up probes that drive
events. Configuration scripts should call addEventProbe() to configure
custom events or high-level methods to configure architected
events. The Python implementation of addEventProbe() automatically
delays event type registration until after instantiation.

In order to support CPU switching and some combined counters (e.g.,
memory references synthesized from loads and stores), the PMU allows
multiple probes per event type. When creating a system that switches
between CPU models that share the same PMU, PMU events for all of the
CPU models can be registered with the PMU.

Kudos to Matt Horsnell for the initial gem5 implementation of the PMU.

arm: use condition code registers for ARM ISA

Analogous to ee049bf (for x86). Requires a bump of the checkpoint version
and corresponding upgrader code to move the condition code register values
to the new register file.

arm: allow DC instructions by default so SE mode works

arm: Panics in miscreg read functions can be tripped by O3 model

Unimplemented miscregs for the generic timer were guarded by panics
in arm/isa.cc which can be tripped by the O3 model if it speculatively
executes a wrong path containing a mrs instruction with a bad miscreg
index. These registers were flagged as implemented and accessible.
This patch changes the miscreg info bit vector to flag them as
unimplemented and inaccessible. In this case, and UndefinedInst
fault will be generated if the register access is not trapped
by a hypervisor.

arm: Add support for ARMv8 (AArch64 & AArch32)

Note: AArch64 and AArch32 interworking is not supported. If you use an AArch64
kernel you are restricted to AArch64 user-mode binaries. This will be addressed
in a later patch.

Note: Virtualization is only supported in AArch32 mode. This will also be fixed
in a later patch.

Contributors:
Giacomo Gabrielli (TrustZone, LPAE, system-level AArch64, AArch64 NEON, validation)
Thomas Grocutt (AArch32 Virtualization, AArch64 FP, validation)
Mbou Eyole (AArch64 NEON, validation)
Ali Saidi (AArch64 Linux support, code integration, validation)
Edmund Grimley-Evans (AArch64 FP)
William Wang (AArch64 Linux support)
Rene De Jong (AArch64 Linux support, performance opt.)
Matt Horsnell (AArch64 MP, validation)
Matt Evans (device models, code integration, validation)
Chris Adeniyi-Jones (AArch64 syscall-emulation)
Prakash Ramrakhyani (validation)
Dam Sunwoo (validation)
Chander Sudanthi (validation)
Stephan Diestelhorst (validation)
Andreas Hansson (code integration, performance opt.)
Eric Van Hensbergen (performance opt.)
Gabe Black

arch: Make all register index flattening const

This patch makes all the register index flattening methods const for
all the ISAs. As part of this, readMiscRegNoEffect for ARM is also
made const.

mem: Set the cache line size on a system level

This patch removes the notion of a peer block size and instead sets
the cache line size on the system level.

Previously the size was set per cache, and communicated through the
interconnect. There were plenty checks to ensure that everyone had the
same size specified, and these checks are now removed. Another benefit
that is not yet harnessed is that the cache line size is now known at
construction time, rather than after the port binding. Hence, the
block size can be locally stored and does not have to be queried every
time it is used.

A follow-on patch updates the configuration scripts accordingly.

arm: Remove the register mapping hack used when copying TCs

In order to see all registers independent of the current CPU mode, the
ARM architecture model uses the magic MISCREG_CPSR_MODE register to
change the register mappings without actually updating the CPU
mode. This hack is no longer needed since the thread context now
provides a flat interface to the register file. This patch replaces
the CPSR_MODE hack with the flat register interface.

arm: Make ID registers ISA parameters

This patch makes the values of ID_ISARx, MIDR, and FPSID configurable
as ISA parameter values. Additionally, setMiscReg now ignores writes
to all of the ID registers.

Note: This moves the MIDR parameter from ArmSystem to ArmISA for
consistency.

arch: Make the ISA class inherit from SimObject

The ISA class on stores the contents of ID registers on many
architectures. In order to make reset values of such registers
configurable, we make the class inherit from SimObject, which allows
us to use the normal generated parameter headers.

This patch introduces a Python helper method, BaseCPU.createThreads(),
which creates a set of ISAs for each of the threads in an SMT
system. Although it is currently only needed when creating
multi-threaded CPUs, it should always be called before instantiating
the system as this is an obvious place to configure ID registers
identifying a thread/CPU.

Decoder: Remove the thread context get/set from the decoder.

This interface is no longer used, and getting rid of it simplifies the
decoders and code that sets up the decoders. The thread context had been used
to read architectural state which was used to contextualize the instruction
memory as it came in. That was changed so that the state is now sent to the
decoders to keep locally if/when it changes. That's significantly more
efficient.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>

ARM: Keep a copy of the fpscr len and stride fields in the decoder.
Avoid reading them every instruction, and also eliminate the last use of the
thread context in the decoders.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>

ARM: fix value of MISCREG_CTR returned by readMiscReg()

According to the A15 TRM the value of this register is as follows (assuming 16 word = 64 byte lines)
[31:29] Format - b100 specifies v7
[28] RAZ - b0
[27:24] CWG log2(max writeback size #words) - 0x4 16 words
[23:20] ERG log2(max reservation size #words) - 0x4 16 words
[19:16] DminLine log2(smallest dcache line #words) - 0x4 16 words
[15:14] L1Ip L1 index/tagging policy - b11 specifies PIPT
[13:4] RAZ - b0000000000
[3:0] IminLine log2(smallest icache line #words) - 0x4 16 words

ARM: Fix MPIDR and MIDR register implementation.

This change allows designating a system as MP capable or not as some
bootloaders/kernels care that it's set right. You can have a single
processor MP capable system, but you can't have a multi-processor
UP only system. This change also fixes the initialization of the MIDR
register.

CheckerCPU: Make CheckerCPU runtime selectable instead of compile selectable

Enables the CheckerCPU to be selected at runtime with the --checker option
from the configs/example/fs.py and configs/example/se.py configuration
files. Also merges with the SE/FS changes.

ARM: FIx a bug preventing multiple cores booting a VExpress_EMM machine.

New kernel code verifies that multi-processor extensions are available
before booting secondary CPUs.

ARM: Add support for Versatile Express extended memory map

Also clean up how we create boot loader memory a bit.

ARM: Add limited CP14 support.

New kernels attempt to read CP14 what debug architecture is available.
These changes add the debug registers and return that none is currently
available.

mem: Add a master ID to each request object.

This change adds a master id to each request object which can be
used identify every device in the system that is capable of issuing a request.
This is part of the way to removing the numCpus+1 stats in the cache and
replacing them with the master ids. This is one of a series of changes
that make way for the stats output to be changed to python.

CheckerCPU: Re-factor CheckerCPU to be compatible with current gem5

Brings the CheckerCPU back to life to allow FS and SE checking of the
O3CPU. These changes have only been tested with the ARM ISA. Other
ISAs potentially require modification.

ARM: Implement numcpus bits in L2CTLR register.

ARM: Mark some variables uncacheable until boot all CPUs are enabled.

There are a set of locations is the linux kernel that are managed via
cache maintence instructions until all processors enable their MMUs & TLBs.
Writes to these locations are manually flushed from the cache to main
memory when the occur so that cores operating without their MMU enabled
and only issuing uncached accesses can receive the correct data. Unfortuantely,
gem5 doesn't support any kind of software directed maintence of the cache.
Until such time as that support exists this patch marks the specific cache blocks
that need to be coherent as non-cacheable until all CPUs enable their MMU and
thus allows gem5 to boot MP systems with caches enabled (a requirement for
booting an O3 cpu and thus an O3 CPU regression).

ARM: Add support for DIV/SDIV instructions.

ARM: Add two unimplemented miscellaneous registers.

Adds MISCREG_ID_MMFR2 and removes break on access to MISCREG_CLIDR. Both
registers now return values that are consistent with current ARM
implementations.

ARM: Remove the saturating (Q) condition code from the renamed register.

Move the saturating bit (which is also saturating) from the renamed register
that holds the flags to the CPSR miscreg and adds a allows setting it in a
similar way to the FP saturating registers. This removes a dependency in
instructions that don't write, but need to preserve the Q bit.

ARM: Better RealView/Versatile EB platform support.

Add registers and components to better support the VersatileEB board.
Made the MIDR and SYS_ID register parameters to ArmSystem and RealviewCtrl
respectively.

ARM: Add support for MP misc regs and broadcast flushes.

trace: reimplement the DTRACE function so it doesn't use a vector
At the same time, rename the trace flags to debug flags since they
have broader usage than simply tracing. This means that
--trace-flags is now --debug-flags and --trace-help is now --debug-help

ARM: Fix checkpoint restoration into O3 CPU and the way O3 switchCpu works.

This change fixes a small bug in the arm copyRegs() code where some registers
wouldn't be copied if the processor was in a mode other than MODE_USER.
Additionally, this change simplifies the way the O3 switchCpu code works by
utilizing TheISA::copyRegs() to copy the required context information
rather than the adhoc copying that goes on in the CPU model. The current code
makes assumptions about the visibility of int and float registers that aren't
true for all architectures in FS mode.

ARM: Cleanup and small fixes to some NEON ops to match the spec.

Only certain bits of the cpacr can be written, some must be equal.
Mult instructions that write the same register should do something sane

ARM: Cleanup implementation of ITSTATE and put important code in PCState.

Consolidate all code to handle ITSTATE in the PCState object rather than
touching a variety of structures/objects.

ARM: Implement the Instruction Set Attribute Registers (ISAR).

The ISAR registers describe which features the processor supports.
Transcribe the values listed in section B5.2.5 of the ARM ARM
into the registers as read-only values

ARM: Reset simulation statistics when pref counters are reset.

The ARM performance counters are not currently supported by the model.
This patch interprets a 'reset performance counters' command to mean 'reset
the simulator statistics' instead.

O3: Make all instructions that write a misc. register not perform the write until commit.

ARM instructions updating cumulative flags (ARM FP exceptions and saturation
flags) are not serialized.

Added aliases for ARM FP exceptions and saturation flags in FPSCR. Removed
write accesses to the FP condition codes for most ARM VFP instructions: only
VCMP and VCMPE instructions update the FP condition codes. Removed a potential
cause of seg. faults in the O3 model for NEON memory macro-ops (ARM).

ARM: Return an FailUnimp instruction when an unimplemented CP15 register is accessed.

Just panicing in readMiscReg() doesn't work because a speculative access
in the o3 model can end the simulation.

ARM: Cache the misc regs at the TLB to limit readMiscReg() calls.

ARM: Keep the warnings to a minimum.

These warnings still need to be addresses, but pages of them is
counterproductive.

ISA,CPU,etc: Create an ISA defined PC type that abstracts out ISA behaviors.



This change is a low level and pervasive reorganization of how PCs are managed
in M5. Back when Alpha was the only ISA, there were only 2 PCs to worry about,
the PC and the NPC, and the lsb of the PC signaled whether or not you were in
PAL mode. As other ISAs were added, we had to add an NNPC, micro PC and next
micropc, x86 and ARM introduced variable length instruction sets, and ARM
started to keep track of mode bits in the PC. Each CPU model handled PCs in
its own custom way that needed to be updated individually to handle the new
dimensions of variability, or, in the case of ARMs mode-bit-in-the-pc hack,
the complexity could be hidden in the ISA at the ISA implementation's expense.
Areas like the branch predictor hadn't been updated to handle branch delay
slots or micropcs, and it turns out that had introduced a significant (10s of
percent) performance bug in SPARC and to a lesser extend MIPS. Rather than
perpetuate the problem by reworking O3 again to handle the PC features needed
by x86, this change was introduced to rework PC handling in a more modular,
transparent, and hopefully efficient way.


PC type:

Rather than having the superset of all possible elements of PC state declared
in each of the CPU models, each ISA defines its own PCState type which has
exactly the elements it needs. A cross product of canned PCState classes are
defined in the new "generic" ISA directory for ISAs with/without delay slots
and microcode. These are either typedef-ed or subclassed by each ISA. To read
or write this structure through a *Context, you use the new pcState() accessor
which reads or writes depending on whether it has an argument. If you just
want the address of the current or next instruction or the current micro PC,
you can get those through read-only accessors on either the PCState type or
the *Contexts. These are instAddr(), nextInstAddr(), and microPC(). Note the
move away from readPC. That name is ambiguous since it's not clear whether or
not it should be the actual address to fetch from, or if it should have extra
bits in it like the PAL mode bit. Each class is free to define its own
functions to get at whatever values it needs however it needs to to be used in
ISA specific code. Eventually Alpha's PAL mode bit could be moved out of the
PC and into a separate field like ARM.

These types can be reset to a particular pc (where npc = pc +
sizeof(MachInst), nnpc = npc + sizeof(MachInst), upc = 0, nupc = 1 as
appropriate), printed, serialized, and compared. There is a branching()
function which encapsulates code in the CPU models that checked if an
instruction branched or not. Exactly what that means in the context of branch
delay slots which can skip an instruction when not taken is ambiguous, and
ideally this function and its uses can be eliminated. PCStates also generally
know how to advance themselves in various ways depending on if they point at
an instruction, a microop, or the last microop of a macroop. More on that
later.

Ideally, accessing all the PCs at once when setting them will improve
performance of M5 even though more data needs to be moved around. This is
because often all the PCs need to be manipulated together, and by getting them
all at once you avoid multiple function calls. Also, the PCs of a particular
thread will have spatial locality in the cache. Previously they were grouped
by element in arrays which spread out accesses.


Advancing the PC:

The PCs were previously managed entirely by the CPU which had to know about PC
semantics, try to figure out which dimension to increment the PC in, what to
set NPC/NNPC, etc. These decisions are best left to the ISA in conjunction
with the PC type itself. Because most of the information about how to
increment the PC (mainly what type of instruction it refers to) is contained
in the instruction object, a new advancePC virtual function was added to the
StaticInst class. Subclasses provide an implementation that moves around the
right element of the PC with a minimal amount of decision making. In ISAs like
Alpha, the instructions always simply assign NPC to PC without having to worry
about micropcs, nnpcs, etc. The added cost of a virtual function call should
be outweighed by not having to figure out as much about what to do with the
PCs and mucking around with the extra elements.

One drawback of making the StaticInsts advance the PC is that you have to
actually have one to advance the PC. This would, superficially, seem to
require decoding an instruction before fetch could advance. This is, as far as
I can tell, realistic. fetch would advance through memory addresses, not PCs,
perhaps predicting new memory addresses using existing ones. More
sophisticated decisions about control flow would be made later on, after the
instruction was decoded, and handed back to fetch. If branching needs to
happen, some amount of decoding needs to happen to see that it's a branch,
what the target is, etc. This could get a little more complicated if that gets
done by the predecoder, but I'm choosing to ignore that for now.


Variable length instructions:

To handle variable length instructions in x86 and ARM, the predecoder now
takes in the current PC by reference to the getExtMachInst function. It can
modify the PC however it needs to (by setting NPC to be the PC + instruction
length, for instance). This could be improved since the CPU doesn't know if
the PC was modified and always has to write it back.


ISA parser:

To support the new API, all PC related operand types were removed from the
parser and replaced with a PCState type. There are two warts on this
implementation. First, as with all the other operand types, the PCState still
has to have a valid operand type even though it doesn't use it. Second, using
syntax like PCS.npc(target) doesn't work for two reasons, this looks like the
syntax for operand type overriding, and the parser can't figure out if you're
reading or writing. Instructions that use the PCS operand (which I've
consistently called it) need to first read it into a local variable,
manipulate it, and then write it back out.


Return address stack:

The return address stack needed a little extra help because, in the presence
of branch delay slots, it has to merge together elements of the return PC and
the call PC. To handle that, a buildRetPC utility function was added. There
are basically only two versions in all the ISAs, but it didn't seem short
enough to put into the generic ISA directory. Also, the branch predictor code
in O3 and InOrder were adjusted so that they always store the PC of the actual
call instruction in the RAS, not the next PC. If the call instruction is a
microop, the next PC refers to the next microop in the same macroop which is
probably not desirable. The buildRetPC function advances the PC intelligently
to the next macroop (in an ISA specific way) so that that case works.


Change in stats:

There were no change in stats except in MIPS and SPARC in the O3 model. MIPS
runs in about 9% fewer ticks. SPARC runs with 30%-50% fewer ticks, which could
likely be improved further by setting call/return instruction flags and taking
advantage of the RAS.


TODO:

Add != operators to the PCState classes, defined trivially to be !(a==b).
Smooth out places where PCs are split apart, passed around, and put back
together later. I think this might happen in SPARC's fault code. Add ISA
specific constructors that allow setting PC elements without calling a bunch
of accessors. Try to eliminate the need for the branching() function. Factor
out Alpha's PAL mode pc bit into a separate flag field, and eliminate places
where it's blindly masked out or tested in the PC.

ARM: Clean up use of TBit and JBit.

Rather tha constantly using ULL(1) << PcXBitShift define those directly.
Additionally, add some helper functions to further clean up the code.

Faults: Pass the StaticInst involved, if any, to a Fault's invoke method.

Also move the "Fault" reference counted pointer type into a separate file,
sim/fault.hh. It would be better to name this less similarly to sim/faults.hh
to reduce confusion, but fault.hh matches the name of the type. We could change
Fault to FaultPtr to match other pointer types, and then changing the name of
the file would make more sense.

ARM: Set the high bits in the part number so it's considered new by some code.

ARM: Fix VFP enabled checks for mem instructions

ARM: Implement CPACR register and return Undefined Instruction when FP access is disabled.

ARM: Clean up flattening for SPSR adding

ARM: Get SCTLR TE bit from reset SCTLR

ARM: We don't currently support ThumbEE exceptions, so don't report that we do

ARM: Implement some more misc registers

ARM: Fix issue with m5.fast and ARM

ARM: Added support for Access Flag and some CP15 regs (V2PCWPR, V2PCWPW, V2PCWUR, V2PCWUW,...)

ARM: Move the ISA "clear" function into isa.cc.

ARM: Implement support for the IT instruction and the ITSTATE bits of CPSR.

ARM: Some TLB bug fixes.

ARM: Move Miscreg functions out of isa.hh

ARM: Fold the MiscRegFile all the way into the ISA object.

Registers: Add an ISA object which replaces the MiscRegFile.
This object encapsulates (or will eventually) the identity and characteristics
of the ISA in the CPU.