[0/9] LoongArch: Preliminary ClangBuiltLinux enablement

Message

WANG Xuerui June 23, 2023, 1:43 p.m. UTC

From: WANG Xuerui <[e-mail]>

Hi,

It's been a long time since the LoongArch port was upstreamed to LLVM,
and there seems to be evidence that Linux was successfully built with
Clang inside Loongson roughly around that time; however, a lot has
changed since then, and the Linux/LoongArch codebase now makes use of
more novel features that necessitate further work. (The enablement work
is tracked at [1].)

With this patch series and a patched LLVM/LLD ([2] for llvm-objcopy,
and [3] for LLD), a working kernel can be built with `make LLVM=1`;
although currently support for CONFIG_RELOCATABLE and CONFIG_MODULE is
still TODO, we've decided to post the series early to hopefully reduce
the rebase burden. The series contains several useful cleanups anyway.

Regarding how to merge this: because only Patch 8 is outside
arch/loongarch, I'd prefer the series to get merged through Huacai's
tree. The series applies cleanly on top of next-20230622.

Thanks go to the ClangBuiltLinux team, and LoongArch toolchain
maintainers from Loongson and the community alike; without your help
this would come much later, if at all (my free time has been steadily
dwindling this year already).

Your comments are welcome!

[1]: https://github.com/ClangBuiltLinux/linux/issues/1787
[2]: https://reviews.llvm.org/D153609
[3]: https://reviews.llvm.org/D138135

WANG Rui (2):
  LoongArch: Calculate various sizes in the linker script
  LoongArch: extable: Also recognize ABI names of registers

WANG Xuerui (7):
  LoongArch: Prepare for assemblers with proper FCSR bank support
  LoongArch: Make {read,write}_fcsr compatible with LLVM/Clang
  LoongArch: Make the CPUCFG and CSR ops simple aliases of compiler
    built-ins
  LoongArch: Simplify the invtlb wrappers
  LoongArch: Tweak CFLAGS for Clang compatibility
  Makefile: Add loongarch target flag for Clang compilation
  LoongArch: Mark Clang LTO as working

 arch/loongarch/Kconfig                 |  5 ++
 arch/loongarch/Makefile                | 14 ++++-
 arch/loongarch/include/asm/fpregdef.h  |  7 +++
 arch/loongarch/include/asm/gpr-num.h   | 30 ++++++++++
 arch/loongarch/include/asm/loongarch.h | 82 ++++++++------------------
 arch/loongarch/include/asm/tlb.h       | 45 +++++---------
 arch/loongarch/kernel/efi-header.S     |  6 +-
 arch/loongarch/kernel/head.S           |  8 +--
 arch/loongarch/kernel/traps.c          |  2 +-
 arch/loongarch/kernel/vmlinux.lds.S    |  7 +++
 arch/loongarch/lib/dump_tlb.c          |  6 +-
 arch/loongarch/mm/tlb.c                | 10 ++--
 arch/loongarch/vdso/Makefile           |  6 +-
 scripts/Makefile.clang                 |  1 +
 14 files changed, 122 insertions(+), 107 deletions(-)