From: WANG Xuerui <git@xxxxxxxxxx> 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/Clang/LLD ([2][3][4][5]), 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 [4]: https://reviews.llvm.org/D150196 [5]: https://reviews.llvm.org/D153707 Changes in v3: - Squashed the two CFLAGS patches into one, and removed the CC_IS_CLANG check in favor of a feature detection approach (Huacai and Ruoyao) - Removed unnecessary BUILD_BUG_ONs in the invtlb wrappers, and made them __always_inline (Ruoyao and Bibo) - Linked to the explanation regarding the Clang triple's "libc" part (Nick) - Fixed a wrong punctuation in commit message of Patch 4 Changes in v2: - Merged the two FCSR-related patches, now using the same approach for assembly and C (given that the inline asm codepath cannot be removed right away), also change terminology: register "class" instead of "bank" - Restored signatures of invtlb wrappers for ease of rebase (potentially downstream product kernels?) - Removed -G0 switches altogether (turned out it's useless upon closer look) - Fix -mabi and -msoft-float handling in the CFLAGS patch; two more LLVM patches are now necessary (the [4] and [5] links above) but the original and correct CFLAGS arrangement now works WANG Rui (2): LoongArch: Calculate various sizes in the linker script LoongArch: extable: Also recognize ABI names of registers WANG Xuerui (6): LoongArch: Prepare for assemblers with proper FCSR class support LoongArch: Make the CPUCFG and CSR ops simple aliases of compiler built-ins LoongArch: Simplify the invtlb wrappers LoongArch: Tweak CFLAGS for Clang compatibility LoongArch: Mark Clang LTO as working Makefile: Add loongarch target flag for Clang compilation arch/loongarch/Kconfig | 5 ++ arch/loongarch/Makefile | 21 +++++--- arch/loongarch/include/asm/fpregdef.h | 7 +++ arch/loongarch/include/asm/gpr-num.h | 30 +++++++++++ arch/loongarch/include/asm/loongarch.h | 72 +++++++------------------- arch/loongarch/include/asm/percpu.h | 6 ++- arch/loongarch/include/asm/tlb.h | 43 +++++++-------- 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/vdso/Makefile | 2 +- scripts/Makefile.clang | 1 + 14 files changed, 118 insertions(+), 98 deletions(-) -- 2.40.0
