arch, sim: Simplify the AuxVector type.

The AuxVector type has a bunch of accessors which just give access to
the underlying variables through references. We might as well just make
those members accessible directly.

Also, the AuxVector doesn't need to handle endianness flips itself. We
can tell the byteswap mechanism how to flip an AuxVector, and let it
handle that for us.

This gets rid of the entire .cc file which was complicated by trying
to both hide the ISA specific endianness translations, and instantiate
templated functions in a .cc.

Change-Id: I433cd61e73e0b067b6d628fba31be4a4ec1c4cf0
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18373
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

riscv: fixed syscall return value

In case of failure, a syscall returns a negative value encoding the
error code. This patch makes the risc-v implementation returns the
encoded value instead of its absolute value upon a failure of a syscall.

Change-Id: I6032b0337fe1cff5b326dbc6bb3b87a415f03300
Reviewed-on: https://gem5-review.googlesource.com/c/9627
Reviewed-by: Alec Roelke <ar4jc@virginia.edu>
Maintainer: Alec Roelke <ar4jc@virginia.edu>

arch-riscv: Enable support for riscv 32-bit in SE mode.

This patch splits up the riscv SE mode support for 32 and 64-bit.
A future patch will add support for decoding rv32 instructions.

Change-Id: Ia79ae19f753caf94dc7e5830a6630efb94b419d7
Signed-off-by: Austin Harris <austinharris@utexas.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/15355
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Alec Roelke <alec.roelke@gmail.com>
Maintainer: Alec Roelke <alec.roelke@gmail.com>

riscv: Get rid of some ISA specific register types.

Change-Id: Ie812cf1d42536094273ba2ec731c16cca38db100
Reviewed-on: https://gem5-review.googlesource.com/c/14466
Reviewed-by: Alec Roelke <alec.roelke@gmail.com>
Maintainer: Alec Roelke <alec.roelke@gmail.com>

syscall_emul: expand AuxVector class

The AuxVector class is responsible for holding Process data.
The data that it holds is normally setup by an OS kernel in
the process address space. The purpose behind doing this is
to pass in information that the process will need for various
reasons. (Check out the enum in the header file for an idea of
what the AuxVector holds.)

The AuxVector struct was changed into a class and encapsulation
methods were added to protect access to the member variables.

The host ISA may have a different endianness than the simulated
ISA. Since data is passed between the process address space and
the simulator for auxiliary vectors, we need to worry about
maintaining endianness for the right context.

Change-Id: I32c5ac4b679559886e1efeb4b5483b92dfc94af9
Reviewed-on: https://gem5-review.googlesource.com/12109
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>

arch-riscv: Update CSR implementations

This patch updates the CSRs to match the RISC-V privileged specification
version 1.10. As interrupts, faults, and privilege levels are not yet
supported, there are no meaninful side effects that are implemented.
Performance counters are also not yet implemented, as they do not have
specifications. Currently they act as cycle counters.

Note that this implementation trusts software to use the registers
properly. Access protection, readability, and writeability of registers
based on privilege will come in a future patch.

Change-Id: I1de89bdbe369b5027911b2e6bc0425d3acaa708a
Reviewed-on: https://gem5-review.googlesource.com/7441
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Alec Roelke <ar4jc@virginia.edu>

arch, mem, sim: Consolidate and rename the SE mode page table classes.

Now that Nothing inherits from PageTableBase directly, it can be
merged into FuncPageTable. This change also takes the opportunity to
rename the combined class to EmulationPageTable which lets you know
that it's specifically for SE mode.

Also remove the page table entry cache since it doesn't seem to
actually improve performance. The TLBs likely absorb the majority of
the locality, essentially acting like a cache like they would in real
hardware.

Change-Id: If1bcb91aed08686603bf7bee37298c0eee826e13
Reviewed-on: https://gem5-review.googlesource.com/7342
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>

arch: Fix a fatal_if in most of the arch's process classes.

When switching an assert to a fatal while addressing recent review
feedback, I forgot to reverse the polarity of the condition, making
the fatal fire in exactly the opposite of the conditions it was meant
to.

Change-Id: Icf49864ef449052bbb0d427dca786006166575c4
Reviewed-on: https://gem5-review.googlesource.com/7381
Reviewed-by: Matthias Jung <jungma@eit.uni-kl.de>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

arch,mem: Remove the default value for page size.

This breaks one more architecture dependence outside of the ISAs.

Change-Id: I071f9ed73aef78e1cd1752247c183e30854b2d28
Reviewed-on: https://gem5-review.googlesource.com/6982
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Alexandru Duțu <alexandru.dutu@amd.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>

arch,mem: Move page table construction into the arch classes.

This gets rid of an awkward NoArchPageTable class, and also gives the
arch a place to inject ISA specific parameters (specifically page size)
without having to have TheISA:: in the generic version of these types.

Change-Id: I1412f303460d5c43dafdb9b3cd07af81c908a441
Reviewed-on: https://gem5-review.googlesource.com/6981
Reviewed-by: Alexandru Duțu <alexandru.dutu@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>

arch-riscv: Remove "magic" syscall number constant

getSyscallArg() in RISC-V has an explicit check to make sure that the
register index is within the bounds of the system call register indices
vector. This patch fixes it so that it uses SyscallArgumentRegs.size()
rather than a "magic" constant that has to be updated every time
SyscallArgumentRegs is changed.

Change-Id: I2935d811177dc8028cb3df64b250ba997bc970d8
Reviewed-on: https://gem5-review.googlesource.com/7061
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Alec Roelke <ar4jc@virginia.edu>

arch-riscv: Define AT_RANDOM properly

According to the getauxval(3) man page, the AT_RANDOM aux value should
be a pointer to 16 random bytes. In the initial implementation of
RISC-V, this was based on spike's program stack setup, which copied the
program header table there instead. This patch changes the
implementation to use the proper 16 random bytes, making it compatible
with some RISC-V programs that use custom linker scripts.

Change-Id: Idaae7f19bf3ed3fd06d293e5e9c0b6f778270eb2
Reviewed-on: https://gem5-review.googlesource.com/6681
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Alec Roelke <ar4jc@virginia.edu>

arch-riscv: Increase maximum stack size

This patch increases the maximum stack size of RISC-V, which should help
to reduce problems with programs that allocate large amounts of data on
the stack or do many small allocations.

Change-Id: I1d760050229b12f01a4a8f24c047b587299fef6d
Reviewed-on: https://gem5-review.googlesource.com/6661
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Alec Roelke <ar4jc@virginia.edu>

misc: Rename misc.(hh|cc) to logging.(hh|cc)

These files aren't a collection of miscellaneous stuff, they're the
definition of the Logger interface, and a few utility macros for
calling into that interface (panic, warn, etc.).

Change-Id: I84267ac3f45896a83c0ef027f8f19c5e9a5667d1
Reviewed-on: https://gem5-review.googlesource.com/6226
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>

arch-riscv: Fix bad stack initialization

This patch fixes a problem with RISC-V initial stack setup in SE mode
where the AT_RANDOM aux vector value contains an address that is too
close to the top of the stack and doesn't fit the required 16 bytes. To
fix this, the program header table was added to the top of the stack
just like the RISC-V proxy kernel does.

Change-Id: I814562e060ff041cd0d7a7c54c3685645bd325a3
Reviewed-on: https://gem5-review.googlesource.com/3401
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Maintainer: Alec Roelke <ar4jc@virginia.edu>

riscv: Fix crashes with large or frequent mmaps

This patch fixes a bug where increasing the mmap region too much causes
it to run into already-allocated memory, which causes gem5 to fail an
assertion. Previously, the stack was incorrectly set up such that the
end of the mmap region and the top of the stack were the same address
and both would grow downward. With this patch, the top of the stack has
been separated from the end of mmap and moved up, and the mmap region
now grows upward instead of downward.

[Rebase to master branch and remove dependencies.]

Change-Id: I7271ff478fff2994f918bc5003a6139b9ba6a520
Reviewed-on: https://gem5-review.googlesource.com/2680
Maintainer: Alec Roelke <ar4jc@virginia.edu>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

riscv: fix compatibility with Linux toolchain

Previously, RISC-V in gem5 only supported RISC-V's Newlib toolchain
(riscv64-unknown-elf-*) due to incorrect assumptions made in the initial
setup of the user stack in SE mode. This patch fixes that by referring
to the RISC-V proxy kernel code (https://github.com/riscv/riscv-pk) and
setting up the stack according to how it does it. Now binaries compiled
using the Linux toolchain (riscv64-unknown-linux-gnu-*) will run as
well.

[Update for recent changes to MemState to add accessors and mutators to
get its members.]

Change-Id: I6d2c486df7688efe3df54273e9aa0fd686851285
Reviewed-on: https://gem5-review.googlesource.com/2305
Maintainer: Alec Roelke <ar4jc@virginia.edu>
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

syscall-emul: Move memState into its own file

The Process class is full of implementation details and
structures related to SE Mode. This changeset factors out an
internal class from Process and moves it into a separate file.
The purpose behind doing this is to clean up the code and make
it a bit more modular.

Change-Id: Ic6941a1657751e8d51d5b6b1dcc04f1195884280
Reviewed-on: https://gem5-review.googlesource.com/2263
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

syscall_emul: [PATCH 15/22] add clone/execve for threading and multiprocess simulations

Modifies the clone system call and adds execve system call. Requires allowing
processes to steal thread contexts from other processes in the same system
object and the ability to detach pieces of process state (such as MemState)
to allow dynamic sharing.

syscall_emul: [patch 8/22] refactor process class

Moves aux_vector into its own .hh and .cc files just to get it out of the
already crowded Process files. Arguably, it could stay there, but it's
probably better just to move it and give it files.

The changeset looks ugly around the Process header file, but the goal here is
to move methods and members around so that they're not defined randomly
throughout the entire header file. I expect this is likely one of the reasons
why I several unused variables related to this class. So, the methods are
declared first followed by members. I've tried to aggregate them together
so that similar entries reside near one another.

There are other changes coming to this code so this is by no means the
final product.

syscall_emul: [patch 5/22] remove LiveProcess class and use Process instead

The EIOProcess class was removed recently and it was the only other class
which derived from Process. Since every Process invocation is also a
LiveProcess invocation, it makes sense to simplify the organization by
combining the fields from LiveProcess into Process.

riscv: Fix crash when syscall argument reg index is too high

By default, doSyscall gets the values of six registers to be used for
system call arguments. RISC-V, by convention, only has four. Because
RISC-V's implementation of these indices is as arrays of integers rather
than as base indices plus offsets, trying to get the fifth argument
register's value will cause a crash. This patch fixes that by returning 0
for any index higher than 3.

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

style: [patch 3/22] reduce include dependencies in some headers

Used cppclean to help identify useless includes and removed them. This
involved erroneously included headers, but also cases where forward
declarations could have been used rather than a full include.

arch: [Patch 1/5] Added RISC-V base instruction set RV64I

First of five patches adding RISC-V to GEM5. This patch introduces the
base 64-bit ISA (RV64I) in src/arch/riscv for use with syscall emulation.
The multiply, floating point, and atomic memory instructions will be added
in additional patches, as well as support for more detailed CPU models.
The loader is also modified to be able to parse RISC-V ELF files, and a
"Hello world\!" example for RISC-V is added to test-progs.

Patch 2 will implement the multiply extension, RV64M; patch 3 will implement
the floating point (single- and double-precision) extensions, RV64FD;
patch 4 will implement the atomic memory instructions, RV64A, and patch 5
will add support for timing, minor, and detailed CPU models that is missing
from the first four patches (such as handling locked memory).

[Removed several unused parameters and imports from RiscvInterrupts.py,
RiscvISA.py, and RiscvSystem.py.]
[Fixed copyright information in RISC-V files copied from elsewhere that had
ARM licenses attached.]
[Reorganized instruction definitions in decoder.isa so that they are sorted
by opcode in preparation for the addition of ISA extensions M, A, F, D.]
[Fixed formatting of several files, removed some variables and
instructions that were missed when moving them to other patches, fixed
RISC-V Foundation copyright attribution, and fixed history of files
copied from other architectures using hg copy.]
[Fixed indentation of switch cases in isa.cc.]
[Reorganized syscall descriptions in linux/process.cc to remove large
number of repeated unimplemented system calls and added implmementations
to functions that have received them since it process.cc was first
created.]
[Fixed spacing for some copyright attributions.]
[Replaced the rest of the file copies using hg copy.]
[Fixed style check errors and corrected unaligned memory accesses.]
[Fix some minor formatting mistakes.]
Signed-off by: Alec Roelke

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