[PATCH] loongarch: rust: Switch to use built-in rustc target

[WANG Rui]

This commit switches to using the built-in rustc
loongarch64-unknown-none-softfloat target for LoongArch.

The Rust samples have been tested with this commit.

Signed-off-by: WANG Rui <wangrui@xxxxxxxxxxx>
---
base-commit: ("rust: Refactor the build target to allow the use of builtin targets")
Link: https://lore.kernel.org/r/20231020155056.3495121-2-Jamie.Cunliffe@xxxxxxx
---
 arch/loongarch/Makefile         | 2 +-
 rust/Makefile                   | 2 +-
 scripts/Makefile                | 2 +-
 scripts/generate_rust_target.rs | 7 +------
 4 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index df6caf79537a..17aabe7b0315 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -101,7 +101,7 @@ ifdef CONFIG_OBJTOOL
 KBUILD_CFLAGS			+= -fno-jump-tables
 endif
 
-KBUILD_RUSTFLAGS			+= --target=$(objtree)/scripts/target.json
+KBUILD_RUSTFLAGS			+= --target=loongarch64-unknown-none-softfloat
 KBUILD_RUSTFLAGS_MODULE		+= -Crelocation-model=pic
 
 ifeq ($(CONFIG_RELOCATABLE),y)
diff --git a/rust/Makefile b/rust/Makefile
index fe045dbc701e..cb40a1ce1331 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -437,7 +437,7 @@ $(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--re
 $(obj)/core.o: private rustc_target_flags = $(core-cfgs)
 $(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
 	$(call if_changed_dep,rustc_library)
-ifneq ($(or $(CONFIG_X86_64),$(CONFIG_LOONGARCH)),)
+ifdef CONFIG_X86_64
 $(obj)/core.o: scripts/target.json
 endif
 
diff --git a/scripts/Makefile b/scripts/Makefile
index bc90520a5426..fe56eeef09dd 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -12,7 +12,7 @@ hostprogs-always-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE)	+= insert-sys-cert
 hostprogs-always-$(CONFIG_RUST_KERNEL_DOCTESTS)		+= rustdoc_test_builder
 hostprogs-always-$(CONFIG_RUST_KERNEL_DOCTESTS)		+= rustdoc_test_gen
 
-ifneq ($(or $(CONFIG_X86_64),$(CONFIG_LOONGARCH)),)
+ifdef CONFIG_X86_64
 always-$(CONFIG_RUST)					+= target.json
 filechk_rust_target = $< < include/config/auto.conf
 
diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs
index 54919cf48621..acd3b1acef83 100644
--- a/scripts/generate_rust_target.rs
+++ b/scripts/generate_rust_target.rs
@@ -164,12 +164,7 @@ fn main() {
         ts.push("llvm-target", "x86_64-linux-gnu");
         ts.push("target-pointer-width", "64");
     } else if cfg.has("LOONGARCH") {
-        ts.push("arch", "loongarch64");
-        ts.push("data-layout", "e-m:e-p:64:64-i64:64-i128:128-n64-S128");
-        ts.push("features", "-f,-d");
-        ts.push("llvm-target", "loongarch64-linux-gnusf");
-        ts.push("llvm-abiname", "lp64s");
-        ts.push("target-pointer-width", "64");
+        panic!("loongarch uses the builtin rustc loongarch64-unknown-none-softfloat target");
     } else {
         panic!("Unsupported architecture");
     }
-- 
2.44.0