Re: [PATCH V2] LoongArch: Add efistub booting support

From: Huacai Chen
Date: Fri Aug 19 2022 - 04:16:15 EST

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In reply to: Ard Biesheuvel: "Re: [PATCH V2] LoongArch: Add efistub booting support"
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Hi, Ard,

On Fri, Aug 19, 2022 at 1:04 AM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote:
>
> On Thu, 18 Aug 2022 at 05:07, Huacai Chen <chenhuacai@xxxxxxxxxxx> wrote:
> >
> > 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@xxxxxxxxxxx>
> > Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
> > ---
> > 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.
> >
> > arch/loongarch/Kconfig | 9 ++
> > arch/loongarch/Makefile | 7 +-
> > arch/loongarch/boot/Makefile | 8 +-
> > arch/loongarch/include/asm/efi.h | 10 +-
> > 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 | 31 ++++--
> > drivers/firmware/efi/libstub/loongarch-stub.c | 60 +++++++++++
> > include/linux/pe.h | 2 +
> > 15 files changed, 282 insertions(+), 24 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..2bd0a574ed73 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
> >
>
> Nit: I am not 100% whether it matters or not, but all other
> architectures use := for these assignments.
>
> Also, in order to be able to use vmlinux.elf or vmlinux.efi as a make
> target directly, other architectures seem to use something like
>
> all: $(notdir $(KBUILD_IMAGE))
>
> vmlinux.elf vmlinux.efi: vmlinux
> $(Q)$(MAKE) $(build)=$(boot) $(bootvars-y) $(boot)/$@
>
> Adopting this will make it easier to wire up the generic zboot support too.
OK, I will change the Makefile as you suggested.

>
> > #
> > # 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
> > 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..c7507a240f30 100644
> > --- a/arch/loongarch/include/asm/efi.h
> > +++ b/arch/loongarch/include/asm/efi.h
> > @@ -18,8 +18,14 @@ void efifb_setup_from_dmi(struct screen_info *si, const char *opt);
> >
> > #define EFI_ALLOC_ALIGN SZ_64K
> >
> > -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);
> > +
>
> These are a bit nasty: could you perhaps add a comment that explains
> why exactly we need to emit these values like this? Using
> kernel_offset with an offset to itself just to be able to refer to
> _text from loongarch-stub.c is especially horrid, so bonus points if
> you can find a better way to do that, preferably without asm
> variables.
This is due to a link problem. Our vmlinux is not PIC, but the stub is
PIC, then the stub code cannot access _text and other symbols defined
in vmlinux.lds.S, because the link address is too far for the stub.

>
> > +#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);
> > }
> >
>
> Why is this taken from the SMBIOS data?
This is removing obsolete code. Before we use generic stub, we use
SMBIOS as an indication whether we have efi support.

>
> > 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..efb9219d8d49 100644
> > --- a/drivers/firmware/efi/libstub/efi-stub.c
> > +++ b/drivers/firmware/efi/libstub/efi-stub.c
> > @@ -40,14 +40,19 @@
> >
> > #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
> >
> > +/*
> > + * 0: No flat mapping
> > + * 1: Flat mapping that VA = PA
> > + * 2: Flat mapping that VA = PA + PAGE_OFFSET
> > + */
> > +static int flat_va_mapping;
> > static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
> > -static bool flat_va_mapping;
> >
>
> Can we change this around a bit?
>
> static bool flat_va_mapping = __is_defined(EFI_RT_FIXED_VIRTUAL_OFFSET);
>
> #ifndef EFI_RT_FIXED_VIRTUAL_OFFSET
> #define EFI_RT_FIXED_VIRTUAL_OFFSET 0
> #endif
>
> Then, in your arch's asm/efi.h, you can add
>
> #define EFI_RT_FIXED_VIRTUAL_OFFSET PAGE_OFFSET
Good idea, I will change to use the new method and send V3 asap.

Huacai
>
> ...
> > @@ -254,9 +260,11 @@ 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 &
> > - EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
> > + attrib = prop_tbl ? prop_tbl->memory_protection_attribute : 0;
> > + if (attrib & EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA)
> > + flat_va_mapping = 1;
> > + if (IS_ENABLED(CONFIG_LOONGARCH))
> > + flat_va_mapping = 2;
> >
>
> Keep the original code but change it into
>
> flat_va_mapping |= ....
>
> (and drop the rest of the change)
>
> > /* force efi_novamap if SetVirtualAddressMap() is unsupported */
> > efi_novamap |= !(get_supported_rt_services() &
> > @@ -338,7 +346,16 @@ 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;
>
> Change this into
>
> in->virt_addr = in->phys_addr + EFI_RT_FIXED_VIRTUAL_OFFSET;
>
> > + switch (flat_va_mapping) {
> > + case 1:
> > + in->virt_addr = in->phys_addr;
> > + break;
> > + case 2:
> > + in->virt_addr = in->phys_addr + PAGE_OFFSET;
> > + break;
> > + default:
> > + in->virt_addr = in->phys_addr;
> > + }
>
> And drop the switch
>
> > 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@xxxxxxxxxxx>
> > + * Huacai Chen <chenhuacai@xxxxxxxxxxx>
> > + * 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
>
> This is looking really good now! Thanks for taking my feedback so seriously.
>
> We will have to figure out how to queue this up, given that I intend
> to queue the generic EFI zboot changes for v6.1 as well.

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