arch-arm: Fix HVC trapping beahviour

This patch is fixing HVC trapping behaviour, reusing the pseudocode
implementation provided in the arm arm.

Change-Id: I0bc81478400b99d84534c1c8871f894722f547c5
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/13776
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Make hlt64 a mem barrier with semihosting

The HLT instruction is used to trap into semihosting. The semihosting
code can change the contents of memory behind the back of the CPU,
which requires instructions triggering semihosting to be
non-speculative and memory barriers.

Change-Id: I735166251aa194120ad49c08082d4ac65fe96524
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8373
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: HLT using immediate when checking for semihosting

HLT can use the immediate field when checking for semihosting,
rather than re-parsing it from the machInst variable.

Change-Id: I072cb100029da34d129b90c5d17e1728f9016c88
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8369
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Fix Hlt64,Svc64,Hvc64,Smc64,Brk64 disassembly

This patch fixes the disassembly of AArch64 Exception Generating
instructions, which were not printing the encoded immediate field. This
has been accomplished by changing their underlying type to a newly
defined one.

Change-Id: If58ae3e620d2baa260e12ecdc850225adfcf1ee5
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8368
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Add aarch64 semihosting support

Add basic support for Arm Semihosting 2.0 simulation calls [1]. These
calls let the guest system call a simulator or debugger to request
OS-like support when running bare metal code.

With the exception of SYS_SYSTEM, this implementation supports all of
the Semihosting 2.0 specification in aarch64.

[1] https://developer.arm.com/docs/100863/latest/preface

Change-Id: I08c153c18a4a4fb9f95d318e2a029724935192a7
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jack Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8147
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>

arch-arm: Removing Serializing flag from ISB

ISB Serializing behaviour is guaranteed by IsSquashAfter,
which is inherently serializing; when instruction is commited,
consecutive instructions are flushed and refetched.

Change-Id: I05e61b4cf9f01113d95b1502c996d04cbd69b759
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5701
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Add support for the brk instruction

Add support for software breakpoints as signalled by the aarch64 brk
instruction. This introduces a new SoftwareBreakpoint fault.

Change-Id: I93646c3298e09d7f7b0983108ba8937c7331297a
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5721
Reviewed-by: Giacomo Gabrielli <Giacomo.Gabrielli@arm.com>

arch-arm: HVC instruction undefined in secure EL1

Since EL2 is not available in secure mode, any HVC call from secure mode
should be treated as undefined. This behaviour was implemented in
aarch32 HVC but not in 64 bit version

Change-Id: Ibaa4d8b1e8fe01d2ba3ef07494c09a4d3e7e87b0
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5921
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Dsb instruction shouldn't flush the pipeline

DSB Instruction shouldn't flush the pipeline, hence the IsSquashAfter
attribute will be removed for either the 32 and 64 bit version.

Change-Id: I98b2b8bc78aa28445ed1a9b5f34645f8d71616ad
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5363
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Removing FlushPipe fault, using SquashAfter

This Patch is removing the FlushPipe ArmFault, which was used for
flushing the pipeline in favour of the general IsSquashAfter StaticInstr
flag. Using a fault was preventing tracers from tracing barriers like
ISB and from adding them to the instruction count

Change-Id: I176e9254eca904694f2f611eb486c55e50ec61ff
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5361
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arm: Add AArch64 hypervisor call instruction 'hvc'

This patch adds the AArch64 instruction hvc which raises an exception
from EL1 into EL2. The host OS uses this instruction to world switch
into the guest.

Change-Id: I930ee43f4f0abd4b35a68eb2a72e44e3ea6570be

arm: Fixes based on UBSan and static analysis

Another churn to clean up undefined behaviour, mostly ARM, but some
parts also touching the generic part of the code base.

Most of the fixes are simply ensuring that proper intialisation. One
of the more subtle changes is the return type of the sign-extension,
which is changed to uint64_t. This is to avoid shifting negative
values (undefined behaviour) in the ISA code.

arch: Use shared_ptr for all Faults

This patch takes quite a large step in transitioning from the ad-hoc
RefCountingPtr to the c++11 shared_ptr by adopting its use for all
Faults. There are no changes in behaviour, and the code modifications
are mostly just replacing "new" with "make_shared".

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