Initial LoongArch support

The LLD port is still in review, so do not add it to the default list of
architectures.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>

build.py

@@ -17,6 +17,7 @@
 import lkt.arm64
 import lkt.hexagon
 import lkt.i386
+import lkt.loongarch
 import lkt.mips
 import lkt.powerpc
 import lkt.riscv
@@ -40,14 +41,17 @@
     's390',
     'x86_64',
 ]
+EXPERIMENTAL_ARCHITECTURES = [
+    'loongarch',
+]
 
 
 def parse_arguments():
     parser = ArgumentParser(description='Build a set of Linux kernels with LLVM')
 
     parser.add_argument('-a',
                         '--architectures',
-                        choices=SUPPORTED_ARCHITECTURES,
+                        choices=[*SUPPORTED_ARCHITECTURES, *EXPERIMENTAL_ARCHITECTURES],
                         default=SUPPORTED_ARCHITECTURES,
                         metavar='ARCH',
                         nargs='+',
@@ -183,6 +187,7 @@ def interrupt_handler(_signum, _frame):
         'arm64': lkt.arm64.Arm64LKTRunner,
         'hexagon': lkt.hexagon.HexagonLKTRunner,
         'i386': lkt.i386.I386LKTRunner,
+        'loongarch': lkt.loongarch.LoongArchLKTRunner,
         'mips': lkt.mips.MipsLKTRunner,
         'powerpc': lkt.powerpc.PowerPCLKTRunner,
         'riscv': lkt.riscv.RISCVLKTRunner,

lkt/loongarch.py

@@ -0,0 +1,90 @@
+#!/usr/bin/env python3
+
+import lkt.runner
+
+KERNEL_ARCH = 'loongarch'
+CLANG_TARGET = 'loongarch64-linux-gnusf'
+
+# See https://github.com/ClangBuiltLinux/linux/issues/1787#issuecomment-1603764274 for more info
+BROKEN_CONFIGS = [
+    'CONFIG_MODULES=n',  # need __attribute__((model("extreme"))) in clang
+    'CONFIG_CRASH_DUMP=n',  # selects RELOCATABLE
+    'CONFIG_RELOCATABLE=n',  # ld.lld prepopulates GOT?
+]
+
+
+class LoongArchLLVMKernelRunner(lkt.runner.LLVMKernelRunner):
+
+    def __init__(self):
+        super().__init__()
+
+        self.boot_arch = KERNEL_ARCH
+        self.image_target = 'vmlinuz.efi'
+
+
+class LoongArchLKTRunner(lkt.runner.LKTRunner):
+
+    def __init__(self):
+        super().__init__()
+
+        self.make_vars['ARCH'] = KERNEL_ARCH
+        self.make_vars['LLVM_IAS'] = 1
+
+        self._clang_target = CLANG_TARGET
+
+    def _add_defconfig_runners(self):
+        runner = LoongArchLLVMKernelRunner()
+        runner.bootable = True
+        runner.configs = ['defconfig', *BROKEN_CONFIGS]
+        runner.only_test_boot = self.only_test_boot
+        self._runners.append(runner)
+
+        runner = LoongArchLLVMKernelRunner()
+        runner.bootable = True
+        runner.configs = ['defconfig', *BROKEN_CONFIGS, 'CONFIG_LTO_CLANG_THIN=y']
+        runner.only_test_boot = self.only_test_boot
+        self._runners.append(runner)
+
+    def _add_otherconfig_runners(self):
+        runner = LoongArchLLVMKernelRunner()
+        # Eventually, allmodconfig instead
+        runner.configs = ['allyesconfig', *BROKEN_CONFIGS]
+        if 'CONFIG_WERROR' in self.lsm.configs:
+            runner.configs.append('CONFIG_WERROR=n')
+        self._runners.append(runner)
+
+        runner = LoongArchLLVMKernelRunner()
+        runner.configs = [
+            'allyesconfig',
+            *BROKEN_CONFIGS,
+            'CONFIG_FTRACE=n',
+            'CONFIG_GCOV_KERNEL=n',
+            'CONFIG_LTO_CLANG_THIN=y',
+        ]
+        if 'CONFIG_WERROR' in self.lsm.configs:
+            runner.configs.append('CONFIG_WERROR=n')
+        self._runners.append(runner)
+
+    def run(self):
+        if self._llvm_version < (17, 0, 0):
+            return self._skip(
+                'LLVM < 17.0.0',
+                'LoongArch requires LLVM 17.0.0 or newer to build properly with LLVM=1')
+
+        if '65b66f3531c2' not in self.lsm.commits:
+            print_text = (
+                'LoongArch needs the following series from Linux 6.5 to build properly:\n'
+                '\n'
+                '  * https://git.kernel.org/torvalds/l/65b66f3531c2756356534b4927ba2d4fbbef603f\n'
+                '\n'
+                'Provide a kernel tree with Linux 6.5+ or one with this series to build LoongArch kernels.'
+            )
+            return self._skip('missing 65b66f3531c2', print_text)
+
+        if 'def' in self.targets:
+            self._add_defconfig_runners()
+
+        if not self.only_test_boot and 'other' in self.targets:
+            self._add_otherconfig_runners()
+
+        return super().run()

lkt/source.py

@@ -141,6 +141,11 @@ def __init__(self, linux_source):
         self._add_commit('788dcee0306e1', r"KBUILD_CFLAGS \+= -mlong-calls",
                          'arch/hexagon/Makefile')
 
+        # Commit: Makefile: Add loongarch target flag for Clang compilation
+        # Link: https://git.kernel.org/linus/65b66f3531c2756356534b4927ba2d4fbbef603f
+        # First appeared: v6.5-rc1
+        self._add_commit('65b66f3531c2', 'loongarch64-linux-gnusf', 'scripts/Makefile.clang')
+
         # Commit: s390: always build relocatable kernel
         # Link: https://git.kernel.org/linus/80ddf5ce1c9291cb175d52ed1227134ad48c47ee
         # First appeared: v6.1-rc5~10^2~1