arch, base, dev, sim: Remove now unnecessary casts from PortProxy methods.

Change-Id: Ia73b2d86a10d02fa09c924a4571477bb5f200eb7
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18572
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

arm, mem: Move the SecurePortProxy subclass into it's own file.

The idea of a "secure" memory area/access is specific to ARM and
shouldn't be in the common mem directory, although it's built in to the
generic memory protocol at this point.

Regardless, it should minimially be in its own file like the virtual
and physical port proxy classes are.

Change-Id: I140d4566ee2deded784adb04bcf6f11755a85c0c
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18569
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

mem: Remove the ISA specialized versions of port proxy's read/write.

These selected their behavior based on ifdefs and had to be disabled
when on the NULL ISA. The versions which take an explicit endianness
have been renamed to just read/write instead of readGtoH and writeHtoG
since the direction of the translation is obvious from context.

Change-Id: I6cfbfda6c4481962d442d3370534e50532d41814
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18372
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch-arm: Fix semihosting arg count for SYS_GET_CMDLINE

SYS_GET_CMDLINE was declared as having 1 parameter when it is really
supposed to have two parameters.

Change-Id: Ia364abb4b34834f4d5e598b5adee9585e0815ac8
Reported-by: Steve Capper <steve.capper@arm.com>
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jack Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10022
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>

arch-arm: Add support for semihosting STDIO redirection

The Arm Semihosting layer currently assumes that the guest application
shares STDIO with gem5. This makes it hard to distinguish application
output from gem5's output and makes it impossible to redirect STDIN
when running in interactive mode. Add support for custom STDIO
redirection when instantiating the Semihosting model.

Change-Id: I3411a6b9bfb008ffc3087d8837f59be72bd1e8ae
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Anouk Van Laer <anouk.vanlaer@arm.com>
Reviewed-by: Jack Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10021
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>

arch-arm: Add support for secure state in semihosting

The semihosting component currently issues non-secure memory accesses
using the standard port proxy. This doesn't work when the guest is
running in secure state.

Change-Id: Id34b142cfcd9d77b455c040ae7f7397c29aebbc6
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jack Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8365
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@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>