LoongArch: Add build infrastructure

Add Kbuild, Makefile, Kconfig and link script for LoongArch build
infrastructure.

Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

3 files changed, 139 insertions, 0 deletions

diff --git a/arch/loongarch/kernel/.gitignore b/arch/loongarch/kernel/.gitignore
new file mode 100644
index 000000000000..bbb90f92d051
--- /dev/null
+++ b/arch/loongarch/kernel/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+vmlinux.lds
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
new file mode 100644
index 000000000000..e5a3b2fb9961
--- /dev/null
+++ b/arch/loongarch/kernel/Makefile
@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the Linux/LoongArch kernel.
+#
+
+extra-y		:= head.o vmlinux.lds
+
+obj-y		+= cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
+		   traps.o irq.o idle.o process.o dma.o mem.o io.o reset.o switch.o \
+		   elf.o syscall.o signal.o time.o topology.o inst.o ptrace.o vdso.o
+
+obj-$(CONFIG_ACPI)		+= acpi.o
+obj-$(CONFIG_EFI) 		+= efi.o
+
+obj-$(CONFIG_CPU_HAS_FPU)	+= fpu.o
+
+obj-$(CONFIG_MODULES)		+= module.o module-sections.o
+
+obj-$(CONFIG_PROC_FS)		+= proc.o
+
+CPPFLAGS_vmlinux.lds		:= $(KBUILD_CFLAGS)
diff --git a/arch/loongarch/kernel/vmlinux.lds.S b/arch/loongarch/kernel/vmlinux.lds.S
new file mode 100644
index 000000000000..f6ce24f403c2
--- /dev/null
+++ b/arch/loongarch/kernel/vmlinux.lds.S
@@ -0,0 +1,116 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/sizes.h>
+#include <asm/asm-offsets.h>
+#include <asm/thread_info.h>
+
+#define PAGE_SIZE _PAGE_SIZE
+
+/*
+ * Put .bss..swapper_pg_dir as the first thing in .bss. This will
+ * ensure that it has .bss alignment (64K).
+ */
+#define BSS_FIRST_SECTIONS *(.bss..swapper_pg_dir)
+
+#include <asm-generic/vmlinux.lds.h>
+
+/*
+ * Max avaliable Page Size is 64K, so we set SectionAlignment
+ * field of EFI application to 64K.
+ */
+PECOFF_FILE_ALIGN = 0x200;
+PECOFF_SEGMENT_ALIGN = 0x10000;
+
+OUTPUT_ARCH(loongarch)
+ENTRY(kernel_entry)
+PHDRS {
+	text PT_LOAD FLAGS(7);	/* RWX */
+	note PT_NOTE FLAGS(4);	/* R__ */
+}
+
+jiffies	 = jiffies_64;
+
+SECTIONS
+{
+	. = VMLINUX_LOAD_ADDRESS;
+
+	_text = .;
+	HEAD_TEXT_SECTION
+
+	. = ALIGN(PECOFF_SEGMENT_ALIGN);
+	.text : {
+		TEXT_TEXT
+		SCHED_TEXT
+		CPUIDLE_TEXT
+		LOCK_TEXT
+		KPROBES_TEXT
+		IRQENTRY_TEXT
+		SOFTIRQENTRY_TEXT
+		*(.fixup)
+		*(.gnu.warning)
+	} :text = 0
+	. = ALIGN(PECOFF_SEGMENT_ALIGN);
+	_etext = .;
+
+	EXCEPTION_TABLE(16)
+
+	. = ALIGN(PECOFF_SEGMENT_ALIGN);
+	__init_begin = .;
+	__inittext_begin = .;
+
+	INIT_TEXT_SECTION(PAGE_SIZE)
+	.exit.text : {
+		EXIT_TEXT
+	}
+
+	. = ALIGN(PECOFF_SEGMENT_ALIGN);
+	__inittext_end = .;
+
+	__initdata_begin = .;
+
+	INIT_DATA_SECTION(16)
+	.exit.data : {
+		EXIT_DATA
+	}
+
+	.init.bss : {
+		*(.init.bss)
+	}
+	. = ALIGN(PECOFF_SEGMENT_ALIGN);
+	__initdata_end = .;
+
+	__init_end = .;
+
+	_sdata = .;
+	RO_DATA(4096)
+	RW_DATA(1 << CONFIG_L1_CACHE_SHIFT, PAGE_SIZE, THREAD_SIZE)
+
+	.sdata : {
+		*(.sdata)
+	}
+	.edata_padding : { BYTE(0); . = ALIGN(PECOFF_FILE_ALIGN); }
+	_edata =  .;
+
+	BSS_SECTION(0, SZ_64K, 8)
+	. = ALIGN(PECOFF_SEGMENT_ALIGN);
+
+	_end = .;
+
+	STABS_DEBUG
+	DWARF_DEBUG
+
+	.gptab.sdata : {
+		*(.gptab.data)
+		*(.gptab.sdata)
+	}
+	.gptab.sbss : {
+		*(.gptab.bss)
+		*(.gptab.sbss)
+	}
+
+	DISCARDS
+	/DISCARD/ : {
+		*(.gnu.attributes)
+		*(.options)
+		*(.eh_frame)
+	}
+}