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From:   Huacai Chen <chenhuacai@loongson.cn>
To:     Arnd Bergmann <arnd@arndb.de>, Huacai Chen <chenhuacai@kernel.org>
Cc:     loongarch@lists.linux.dev, linux-arch@vger.kernel.org,
        Xuefeng Li <lixuefeng@loongson.cn>,
        Guo Ren <guoren@kernel.org>, Xuerui Wang <kernel@xen0n.name>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Ard Biesheuvel <ardb@kernel.org>, linux-efi@vger.kernel.org,
        linux-kernel@vger.kernel.org, Huacai Chen <chenhuacai@loongson.cn>,
        Xi Ruoyao <xry111@xry111.site>
Subject: [PATCH V3] LoongArch: Add efistub booting support
Date:   Fri, 19 Aug 2022 18:20:37 +0800
Message-Id: <20220819102037.2697798-1-chenhuacai@loongson.cn>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

This patch adds efistub booting support, which is the standard UEFI boot
protocol for us to use.

We use generic efistub, which means we can pass boot information (i.e.,
system table, memory map, kernel command line, initrd) via a light FDT
and drop a lot of non-standard code.

We use a flat mapping to map the efi runtime in the kernel's address
space. In efi, VA = PA; in kernel, VA = PA + PAGE_OFFSET. As a result,
flat mapping is not identity mapping, SetVirtualAddressMap() is still
needed for the efi runtime.

Tested-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
V1 --> V2:
1, Call SetVirtualAddressMap() in stub;
2, Use core kernel data directly in alloc_screen_info();
3, Remove the magic number in MS-DOS header;
4, Disable EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER;
5, Some other small changes suggested by Ard Biesheuvel.

V2 --> V3:
1, Adjust Makefile to adapt zboot;
2, Introduce EFI_RT_VIRTUAL_OFFSET instead of changing flat_va_mapping.

 arch/loongarch/Kconfig                        |  9 ++
 arch/loongarch/Makefile                       | 13 ++-
 arch/loongarch/boot/Makefile                  |  8 +-
 arch/loongarch/include/asm/efi.h              | 11 ++-
 arch/loongarch/kernel/efi-header.S            | 99 +++++++++++++++++++
 arch/loongarch/kernel/efi.c                   |  3 +
 arch/loongarch/kernel/head.S                  | 20 ++++
 arch/loongarch/kernel/image-vars.h            | 30 ++++++
 arch/loongarch/kernel/setup.c                 | 12 +--
 arch/loongarch/kernel/vmlinux.lds.S           |  1 +
 drivers/firmware/efi/Kconfig                  |  4 +-
 drivers/firmware/efi/libstub/Makefile         | 10 ++
 drivers/firmware/efi/libstub/efi-stub.c       | 16 +--
 drivers/firmware/efi/libstub/loongarch-stub.c | 60 +++++++++++
 include/linux/pe.h                            |  2 +
 15 files changed, 272 insertions(+), 26 deletions(-)
 create mode 100644 arch/loongarch/kernel/efi-header.S
 create mode 100644 arch/loongarch/kernel/image-vars.h
 create mode 100644 drivers/firmware/efi/libstub/loongarch-stub.c

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 9478f9646fa5..4cb412a82afa 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -324,6 +324,15 @@ config EFI
 	  This enables the kernel to use EFI runtime services that are
 	  available (such as the EFI variable services).
 
+config EFI_STUB
+	bool "EFI boot stub support"
+	default y
+	depends on EFI
+	select EFI_GENERIC_STUB
+	help
+	  This kernel feature allows the kernel to be loaded directly by
+	  EFI firmware without the use of a bootloader.
+
 config SMP
 	bool "Multi-Processing support"
 	help
diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index ec3de6191276..4bc47f47cfd8 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -7,7 +7,11 @@ boot	:= arch/loongarch/boot
 
 KBUILD_DEFCONFIG := loongson3_defconfig
 
-KBUILD_IMAGE	= $(boot)/vmlinux
+ifndef CONFIG_EFI_STUB
+KBUILD_IMAGE	:= $(boot)/vmlinux.elf
+else
+KBUILD_IMAGE	:= $(boot)/vmlinux.efi
+endif
 
 #
 # Select the object file format to substitute into the linker script.
@@ -75,6 +79,7 @@ endif
 head-y := arch/loongarch/kernel/head.o
 
 libs-y += arch/loongarch/lib/
+libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
 
 ifeq ($(KBUILD_EXTMOD),)
 prepare: vdso_prepare
@@ -86,10 +91,10 @@ PHONY += vdso_install
 vdso_install:
 	$(Q)$(MAKE) $(build)=arch/loongarch/vdso $@
 
-all:	$(KBUILD_IMAGE)
+all:	$(notdir $(KBUILD_IMAGE))
 
-$(KBUILD_IMAGE): vmlinux
-	$(Q)$(MAKE) $(build)=$(boot) $(bootvars-y) $@
+vmlinux.elf vmlinux.efi: vmlinux
+	$(Q)$(MAKE) $(build)=$(boot) $(bootvars-y) $(boot)/$@
 
 install:
 	$(Q)install -D -m 755 $(KBUILD_IMAGE) $(INSTALL_PATH)/vmlinux-$(KERNELRELEASE)
diff --git a/arch/loongarch/boot/Makefile b/arch/loongarch/boot/Makefile
index 0125b17edc98..fecf34f50e56 100644
--- a/arch/loongarch/boot/Makefile
+++ b/arch/loongarch/boot/Makefile
@@ -8,9 +8,13 @@ drop-sections := .comment .note .options .note.gnu.build-id
 strip-flags   := $(addprefix --remove-section=,$(drop-sections)) -S
 OBJCOPYFLAGS_vmlinux.efi := -O binary $(strip-flags)
 
-targets := vmlinux
 quiet_cmd_strip = STRIP	  $@
       cmd_strip = $(STRIP) -s -o $@ $<
 
-$(obj)/vmlinux: vmlinux FORCE
+targets := vmlinux.elf
+$(obj)/vmlinux.elf: vmlinux FORCE
 	$(call if_changed,strip)
+
+targets += vmlinux.efi
+$(obj)/vmlinux.efi: vmlinux FORCE
+	$(call if_changed,objcopy)
diff --git a/arch/loongarch/include/asm/efi.h b/arch/loongarch/include/asm/efi.h
index 9d44c6948be1..50c54b4174eb 100644
--- a/arch/loongarch/include/asm/efi.h
+++ b/arch/loongarch/include/asm/efi.h
@@ -17,9 +17,16 @@ void efifb_setup_from_dmi(struct screen_info *si, const char *opt);
 #define arch_efi_call_virt_teardown()
 
 #define EFI_ALLOC_ALIGN		SZ_64K
+#define EFI_RT_VIRTUAL_OFFSET	CSR_DMW0_BASE
 
-struct screen_info *alloc_screen_info(void);
-void free_screen_info(struct screen_info *si);
+static inline struct screen_info *alloc_screen_info(void)
+{
+	return &screen_info;
+}
+
+static inline void free_screen_info(struct screen_info *si)
+{
+}
 
 static inline unsigned long efi_get_max_initrd_addr(unsigned long image_addr)
 {
diff --git a/arch/loongarch/kernel/efi-header.S b/arch/loongarch/kernel/efi-header.S
new file mode 100644
index 000000000000..8c1d229a2afa
--- /dev/null
+++ b/arch/loongarch/kernel/efi-header.S
@@ -0,0 +1,99 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+
+#include <linux/pe.h>
+#include <linux/sizes.h>
+
+	.macro	__EFI_PE_HEADER
+	.long	PE_MAGIC
+.Lcoff_header:
+	.short	IMAGE_FILE_MACHINE_LOONGARCH64		/* Machine */
+	.short	.Lsection_count				/* NumberOfSections */
+	.long	0 					/* TimeDateStamp */
+	.long	0					/* PointerToSymbolTable */
+	.long	0					/* NumberOfSymbols */
+	.short	.Lsection_table - .Loptional_header	/* SizeOfOptionalHeader */
+	.short	IMAGE_FILE_DEBUG_STRIPPED | \
+		IMAGE_FILE_EXECUTABLE_IMAGE | \
+		IMAGE_FILE_LINE_NUMS_STRIPPED		/* Characteristics */
+
+.Loptional_header:
+	.short	PE_OPT_MAGIC_PE32PLUS			/* PE32+ format */
+	.byte	0x02					/* MajorLinkerVersion */
+	.byte	0x14					/* MinorLinkerVersion */
+	.long	__inittext_end - .Lefi_header_end	/* SizeOfCode */
+	.long	_end - __initdata_begin			/* SizeOfInitializedData */
+	.long	0					/* SizeOfUninitializedData */
+	.long	__efistub_efi_pe_entry - _head		/* AddressOfEntryPoint */
+	.long	.Lefi_header_end - _head		/* BaseOfCode */
+
+.Lextra_header_fields:
+	.quad	0					/* ImageBase */
+	.long	PECOFF_SEGMENT_ALIGN			/* SectionAlignment */
+	.long	PECOFF_FILE_ALIGN			/* FileAlignment */
+	.short	0					/* MajorOperatingSystemVersion */
+	.short	0					/* MinorOperatingSystemVersion */
+	.short	LINUX_EFISTUB_MAJOR_VERSION		/* MajorImageVersion */
+	.short	LINUX_EFISTUB_MINOR_VERSION		/* MinorImageVersion */
+	.short	0					/* MajorSubsystemVersion */
+	.short	0					/* MinorSubsystemVersion */
+	.long	0					/* Win32VersionValue */
+
+	.long	_end - _head				/* SizeOfImage */
+
+	/* Everything before the kernel image is considered part of the header */
+	.long	.Lefi_header_end - _head		/* SizeOfHeaders */
+	.long	0					/* CheckSum */
+	.short	IMAGE_SUBSYSTEM_EFI_APPLICATION		/* Subsystem */
+	.short	0					/* DllCharacteristics */
+	.quad	0					/* SizeOfStackReserve */
+	.quad	0					/* SizeOfStackCommit */
+	.quad	0					/* SizeOfHeapReserve */
+	.quad	0					/* SizeOfHeapCommit */
+	.long	0					/* LoaderFlags */
+	.long	(.Lsection_table - .) / 8		/* NumberOfRvaAndSizes */
+
+	.quad	0					/* ExportTable */
+	.quad	0					/* ImportTable */
+	.quad	0					/* ResourceTable */
+	.quad	0					/* ExceptionTable */
+	.quad	0					/* CertificationTable */
+	.quad	0					/* BaseRelocationTable */
+
+	/* Section table */
+.Lsection_table:
+	.ascii	".text\0\0\0"
+	.long	__inittext_end - .Lefi_header_end	/* VirtualSize */
+	.long	.Lefi_header_end - _head		/* VirtualAddress */
+	.long	__inittext_end - .Lefi_header_end	/* SizeOfRawData */
+	.long	.Lefi_header_end - _head		/* PointerToRawData */
+
+	.long	0					/* PointerToRelocations */
+	.long	0					/* PointerToLineNumbers */
+	.short	0					/* NumberOfRelocations */
+	.short	0					/* NumberOfLineNumbers */
+	.long	IMAGE_SCN_CNT_CODE | \
+		IMAGE_SCN_MEM_READ | \
+		IMAGE_SCN_MEM_EXECUTE			/* Characteristics */
+
+	.ascii	".data\0\0\0"
+	.long	_end - __initdata_begin			/* VirtualSize */
+	.long	__initdata_begin - _head		/* VirtualAddress */
+	.long	_edata - __initdata_begin		/* SizeOfRawData */
+	.long	__initdata_begin - _head		/* PointerToRawData */
+
+	.long	0					/* PointerToRelocations */
+	.long	0					/* PointerToLineNumbers */
+	.short	0					/* NumberOfRelocations */
+	.short	0					/* NumberOfLineNumbers */
+	.long	IMAGE_SCN_CNT_INITIALIZED_DATA | \
+		IMAGE_SCN_MEM_READ | \
+		IMAGE_SCN_MEM_WRITE			/* Characteristics */
+
+	.set	.Lsection_count, (. - .Lsection_table) / 40
+
+	.balign	0x10000					/* PECOFF_SEGMENT_ALIGN */
+.Lefi_header_end:
+	.endm
diff --git a/arch/loongarch/kernel/efi.c b/arch/loongarch/kernel/efi.c
index a50b60c587fa..1f1f755fb425 100644
--- a/arch/loongarch/kernel/efi.c
+++ b/arch/loongarch/kernel/efi.c
@@ -69,4 +69,7 @@ void __init efi_init(void)
 	config_tables = early_memremap(efi_config_table, efi_nr_tables * size);
 	efi_config_parse_tables(config_tables, efi_systab->nr_tables, arch_tables);
 	early_memunmap(config_tables, efi_nr_tables * size);
+
+	if (screen_info.orig_video_isVGA == VIDEO_TYPE_EFI)
+		memblock_reserve(screen_info.lfb_base, screen_info.lfb_size);
 }
diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
index c60eb66793e3..01bac62a6442 100644
--- a/arch/loongarch/kernel/head.S
+++ b/arch/loongarch/kernel/head.S
@@ -12,6 +12,26 @@
 #include <asm/loongarch.h>
 #include <asm/stackframe.h>
 
+#ifdef CONFIG_EFI_STUB
+
+#include "efi-header.S"
+
+	__HEAD
+
+_head:
+	.word	MZ_MAGIC		/* "MZ", MS-DOS header */
+	.org	0x3c			/* 0x04 ~ 0x3b reserved */
+	.long	pe_header - _head	/* Offset to the PE header */
+
+pe_header:
+	__EFI_PE_HEADER
+
+SYM_DATA(kernel_asize, .long _end - _text);
+SYM_DATA(kernel_fsize, .long _edata - _text);
+SYM_DATA(kernel_offset, .long kernel_offset - _text);
+
+#endif
+
 	__REF
 
 SYM_CODE_START(kernel_entry)			# kernel entry point
diff --git a/arch/loongarch/kernel/image-vars.h b/arch/loongarch/kernel/image-vars.h
new file mode 100644
index 000000000000..c901ebb903f2
--- /dev/null
+++ b/arch/loongarch/kernel/image-vars.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef __LOONGARCH_KERNEL_IMAGE_VARS_H
+#define __LOONGARCH_KERNEL_IMAGE_VARS_H
+
+#ifdef CONFIG_EFI_STUB
+
+__efistub_memcmp		= memcmp;
+__efistub_memchr		= memchr;
+__efistub_memcpy		= memcpy;
+__efistub_memmove		= memmove;
+__efistub_memset		= memset;
+__efistub_strcat		= strcat;
+__efistub_strcmp		= strcmp;
+__efistub_strlen		= strlen;
+__efistub_strncat		= strncat;
+__efistub_strnstr		= strnstr;
+__efistub_strnlen		= strnlen;
+__efistub_strrchr		= strrchr;
+__efistub_kernel_entry		= kernel_entry;
+__efistub_kernel_asize		= kernel_asize;
+__efistub_kernel_fsize		= kernel_fsize;
+__efistub_kernel_offset		= kernel_offset;
+__efistub_screen_info		= screen_info;
+
+#endif
+
+#endif /* __LOONGARCH_KERNEL_IMAGE_VARS_H */
diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 23ee293e1cd2..f938aae3e92c 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -49,9 +49,7 @@
 #define SMBIOS_CORE_PACKAGE_OFFSET	0x23
 #define LOONGSON_EFI_ENABLE		(1 << 3)
 
-#ifdef CONFIG_VT
-struct screen_info screen_info;
-#endif
+struct screen_info screen_info __section(".data");
 
 unsigned long fw_arg0, fw_arg1;
 DEFINE_PER_CPU(unsigned long, kernelsp);
@@ -122,16 +120,9 @@ static void __init parse_cpu_table(const struct dmi_header *dm)
 
 static void __init parse_bios_table(const struct dmi_header *dm)
 {
-	int bios_extern;
 	char *dmi_data = (char *)dm;
 
-	bios_extern = *(dmi_data + SMBIOS_BIOSEXTERN_OFFSET);
 	b_info.bios_size = (*(dmi_data + SMBIOS_BIOSSIZE_OFFSET) + 1) << 6;
-
-	if (bios_extern & LOONGSON_EFI_ENABLE)
-		set_bit(EFI_BOOT, &efi.flags);
-	else
-		clear_bit(EFI_BOOT, &efi.flags);
 }
 
 static void __init find_tokens(const struct dmi_header *dm, void *dummy)
@@ -145,6 +136,7 @@ static void __init find_tokens(const struct dmi_header *dm, void *dummy)
 		break;
 	}
 }
+
 static void __init smbios_parse(void)
 {
 	b_info.bios_vendor = (void *)dmi_get_system_info(DMI_BIOS_VENDOR);
diff --git a/arch/loongarch/kernel/vmlinux.lds.S b/arch/loongarch/kernel/vmlinux.lds.S
index 69c76f26c1c5..36d042739f3c 100644
--- a/arch/loongarch/kernel/vmlinux.lds.S
+++ b/arch/loongarch/kernel/vmlinux.lds.S
@@ -12,6 +12,7 @@
 #define BSS_FIRST_SECTIONS *(.bss..swapper_pg_dir)
 
 #include <asm-generic/vmlinux.lds.h>
+#include "image-vars.h"
 
 /*
  * Max avaliable Page Size is 64K, so we set SectionAlignment
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 6cb7384ad2ac..cbf1c55dc224 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -107,7 +107,7 @@ config EFI_GENERIC_STUB
 
 config EFI_ARMSTUB_DTB_LOADER
 	bool "Enable the DTB loader"
-	depends on EFI_GENERIC_STUB && !RISCV
+	depends on EFI_GENERIC_STUB && !RISCV && !LOONGARCH
 	default y
 	help
 	  Select this config option to add support for the dtb= command
@@ -124,7 +124,7 @@ config EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER
 	bool "Enable the command line initrd loader" if !X86
 	depends on EFI_STUB && (EFI_GENERIC_STUB || X86)
 	default y if X86
-	depends on !RISCV
+	depends on !RISCV && !LOONGARCH
 	help
 	  Select this config option to add support for the initrd= command
 	  line parameter, allowing an initrd that resides on the same volume
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index d0537573501e..1588c61939e7 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -26,6 +26,8 @@ cflags-$(CONFIG_ARM)		:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
 				   $(call cc-option,-mno-single-pic-base)
 cflags-$(CONFIG_RISCV)		:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
 				   -fpic
+cflags-$(CONFIG_LOONGARCH)	:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
+				   -fpic
 
 cflags-$(CONFIG_EFI_GENERIC_STUB) += -I$(srctree)/scripts/dtc/libfdt
 
@@ -70,6 +72,8 @@ lib-$(CONFIG_ARM)		+= arm32-stub.o
 lib-$(CONFIG_ARM64)		+= arm64-stub.o
 lib-$(CONFIG_X86)		+= x86-stub.o
 lib-$(CONFIG_RISCV)		+= riscv-stub.o
+lib-$(CONFIG_LOONGARCH)		+= loongarch-stub.o
+
 CFLAGS_arm32-stub.o		:= -DTEXT_OFFSET=$(TEXT_OFFSET)
 
 # Even when -mbranch-protection=none is set, Clang will generate a
@@ -125,6 +129,12 @@ STUBCOPY_FLAGS-$(CONFIG_RISCV)	+= --prefix-alloc-sections=.init \
 				   --prefix-symbols=__efistub_
 STUBCOPY_RELOC-$(CONFIG_RISCV)	:= R_RISCV_HI20
 
+# For LoongArch, keep all the symbols in .init section and make sure that no
+# absolute symbols references doesn't exist.
+STUBCOPY_FLAGS-$(CONFIG_LOONGARCH)	+= --prefix-alloc-sections=.init \
+					   --prefix-symbols=__efistub_
+STUBCOPY_RELOC-$(CONFIG_LOONGARCH)	:= R_LARCH_MARK_LA
+
 $(obj)/%.stub.o: $(obj)/%.o FORCE
 	$(call if_changed,stubcopy)
 
diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c
index f515394cce6e..90f1335bc46e 100644
--- a/drivers/firmware/efi/libstub/efi-stub.c
+++ b/drivers/firmware/efi/libstub/efi-stub.c
@@ -40,14 +40,18 @@
 
 #ifdef CONFIG_ARM64
 # define EFI_RT_VIRTUAL_LIMIT	DEFAULT_MAP_WINDOW_64
-#elif defined(CONFIG_RISCV)
+#elif defined(CONFIG_RISCV) || defined(CONFIG_LOONGARCH)
 # define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE_MIN
-#else
+#else /* Only if TASK_SIZE is a constant */
 # define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE
 #endif
 
+#ifndef EFI_RT_VIRTUAL_OFFSET
+#define EFI_RT_VIRTUAL_OFFSET	0
+#endif
+
 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
-static bool flat_va_mapping;
+static bool flat_va_mapping = !!EFI_RT_VIRTUAL_OFFSET;
 
 const efi_system_table_t *efi_system_table;
 
@@ -254,8 +258,8 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
 	 * The easiest way to achieve that is to simply use a 1:1 mapping.
 	 */
 	prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
-	flat_va_mapping = prop_tbl &&
-			  (prop_tbl->memory_protection_attribute &
+	flat_va_mapping |= prop_tbl &&
+			   (prop_tbl->memory_protection_attribute &
 			   EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
 
 	/* force efi_novamap if SetVirtualAddressMap() is unsupported */
@@ -338,7 +342,7 @@ void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
 		paddr = in->phys_addr;
 		size = in->num_pages * EFI_PAGE_SIZE;
 
-		in->virt_addr = in->phys_addr;
+		in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET;
 		if (efi_novamap) {
 			continue;
 		}
diff --git a/drivers/firmware/efi/libstub/loongarch-stub.c b/drivers/firmware/efi/libstub/loongarch-stub.c
new file mode 100644
index 000000000000..b7ef8d2df59e
--- /dev/null
+++ b/drivers/firmware/efi/libstub/loongarch-stub.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Author: Yun Liu <liuyun@loongson.cn>
+ *         Huacai Chen <chenhuacai@loongson.cn>
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+
+#include <asm/efi.h>
+#include <asm/addrspace.h>
+#include "efistub.h"
+
+typedef void __noreturn (*kernel_entry_t)(bool efi, unsigned long fdt);
+
+extern int kernel_asize;
+extern int kernel_fsize;
+extern int kernel_offset;
+extern kernel_entry_t kernel_entry;
+
+efi_status_t check_platform_features(void)
+{
+	return EFI_SUCCESS;
+}
+
+efi_status_t handle_kernel_image(unsigned long *image_addr,
+				 unsigned long *image_size,
+				 unsigned long *reserve_addr,
+				 unsigned long *reserve_size,
+				 efi_loaded_image_t *image,
+				 efi_handle_t image_handle)
+{
+	efi_status_t status;
+	unsigned long kernel_addr = 0;
+
+	kernel_addr = (unsigned long)&kernel_offset - kernel_offset;
+
+	status = efi_relocate_kernel(&kernel_addr, kernel_fsize, kernel_asize,
+				     PHYSADDR(VMLINUX_LOAD_ADDRESS), SZ_2M, 0x0);
+
+	*image_addr = kernel_addr;
+	*image_size = kernel_asize;
+
+	return status;
+}
+
+void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt, unsigned long fdt_size)
+{
+	kernel_entry_t real_kernel_entry;
+
+	/* Config Direct Mapping */
+	csr_write64(CSR_DMW0_INIT, LOONGARCH_CSR_DMWIN0);
+	csr_write64(CSR_DMW1_INIT, LOONGARCH_CSR_DMWIN1);
+
+	real_kernel_entry = (kernel_entry_t)
+		((unsigned long)&kernel_entry - entrypoint + VMLINUX_LOAD_ADDRESS);
+
+	if (!efi_novamap)
+		real_kernel_entry(true, fdt);
+	else
+		real_kernel_entry(false, fdt);
+}
diff --git a/include/linux/pe.h b/include/linux/pe.h
index daf09ffffe38..1d3836ef9d92 100644
--- a/include/linux/pe.h
+++ b/include/linux/pe.h
@@ -65,6 +65,8 @@
 #define	IMAGE_FILE_MACHINE_SH5		0x01a8
 #define	IMAGE_FILE_MACHINE_THUMB	0x01c2
 #define	IMAGE_FILE_MACHINE_WCEMIPSV2	0x0169
+#define	IMAGE_FILE_MACHINE_LOONGARCH32	0x6232
+#define	IMAGE_FILE_MACHINE_LOONGARCH64	0x6264
 
 /* flags */
 #define IMAGE_FILE_RELOCS_STRIPPED           0x0001
-- 
2.31.1