Adding baseline Morello support

[heshamelmatary]

This issue is a tracker for adding baseline Morello support including a new CPU and platforms. It is just like any other AArch64 CPU/platform without any CHERI support. Currently, I have Morello ports of seL4 passing all sel4test on QEMU, FVP, and the Morello hardware board. This could build with GCC or LLVM/lld. Initial sel4bench numbers running on the board are attached. While this is a baseline for RFC-15 (as a dependency), it's independent from it whether there's future CHERI support or not. I'll gradually be submitting PRs for this issue and update it accordingly.

There are 4 major efforts for this issue:

• Enable building/running with LLVM/lld.
  This is not a blocker for baseline support as it could also build with GCC. But it's good to make sure the baseline could also build with LLVM/lld for future CHERI support.

  • seL4 kernel changes to allow linking with lld
    • [submitted][merged] Minor changes to enable linking with lld #1077
  • Build system changes to allow building with lld
    • [submitted][!merged] lld: Enable building C projects without cxx crt files seL4_tools#186
  • Fixing bugs and differences between lld and ld.bfd
    • [submitted][merged] Fix: NULL-terminate existing_frames[] array sel4test#99
    • [submitted][merged] lld: Fix .tdata/.tbss addresses when .tdata is empty sel4runtime#17
  • User-level changes to build with LLVM/lld
    • [submitted][!merged] Enable building with lld seL4_libs#75
    • [submitted][!merged] Changes to enable linking with LLVM/lld seL4_tools#173

• seL4 kernel port

  • Add a new Morello CPU
    • [submitted][!merged] morello: Add initial support for a CPU and a QEMU platform #1157
    • [submitted][!merged][optional] Support full 48-bit PA on Morello Zero capPtr for device untyped capabilities #1163
  • [qemu-morello] Add a new QEMU platform
    • [submitted][!merged] morello: Add initial support for a CPU and a QEMU platform #1157
  • [morello-fvp] Add a new FVP platform
    • [submitted][!merged] morello: Add a new FVP platform #1173
  • [morello-soc] Add a new SoC/HW platform
    • [submitted][!merged] morello: Add a new Morello hardware board platform #1174

• sel4test

  • Add support for Morello platforms in the dependent libraries
    • [submitted][!merged] QEMU platform support: morello: Add a new QEMU platform seL4_tools#182
    • [submitted][!merged] QEMU platform support: morello: Add support for QEMU platform util_libs#172
    • [submitted][!merged] FVP platform support: libplatsupport/morello: Add basic drivers for fvp util_libs#175
    • [submitted][!merged] SoC platform support: libplatsupport/morello: Add basic drivers for morello-soc util_libs#177
    • [submitted][!merged] morello: Add FVP and SoC platforms to the EFI list seL4_tools#188

• sel4bench

  • Add a new Morello Hardware platform
  • Add support for events and counters
    • [submitted][!merged] sel4bench/morello: Add a new CPU with PMU events seL4_libs#88
  • Report numbers
    • sel4bench-morello-soc.log

[heshamelmatary]

I believe I've addressed all of the comments on the pending PRs, but please let me know if I have missed any