On Tue, 2020-04-21 at 13:02 -0700, Palmer Dabbelt wrote: > [I just saw there's a v4, so I'm moving over here] > > On Mon, 20 Apr 2020 20:33:35 PDT (-0700), Atish Patra wrote: > > Linux kernel Image can appear as an EFI application With > > appropriate > > PE/COFF header fields in the beginning of the Image header. An EFI > > application loader can directly load a Linux kernel Image and an > > EFI > > stub residing in kernel can boot Linux kernel directly. > > > > Add the necessary PE/COFF header. > > > > Signed-off-by: Atish Patra <atish.patra@xxxxxxx> > > --- > > arch/riscv/include/asm/sections.h | 13 ++++ > > arch/riscv/kernel/Makefile | 4 ++ > > arch/riscv/kernel/efi-header.S | 99 > > +++++++++++++++++++++++++++++++ > > arch/riscv/kernel/head.S | 16 +++++ > > arch/riscv/kernel/image-vars.h | 53 +++++++++++++++++ > > arch/riscv/kernel/vmlinux.lds.S | 20 ++++++- > > 6 files changed, 203 insertions(+), 2 deletions(-) > > create mode 100644 arch/riscv/include/asm/sections.h > > create mode 100644 arch/riscv/kernel/efi-header.S > > create mode 100644 arch/riscv/kernel/image-vars.h > > > > diff --git a/arch/riscv/include/asm/sections.h > > b/arch/riscv/include/asm/sections.h > > new file mode 100644 > > index 000000000000..3a9971b1210f > > --- /dev/null > > +++ b/arch/riscv/include/asm/sections.h > > @@ -0,0 +1,13 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > +/* > > + * Copyright (C) 2020 Western Digital Corporation or its > > affiliates. > > + */ > > +#ifndef __ASM_SECTIONS_H > > +#define __ASM_SECTIONS_H > > + > > +#include <asm-generic/sections.h> > > + > > +extern char _start[]; > > +extern char _start_kernel[]; > > + > > +#endif /* __ASM_SECTIONS_H */ > > diff --git a/arch/riscv/kernel/Makefile > > b/arch/riscv/kernel/Makefile > > index 86c83081044f..86ca755f8a9f 100644 > > --- a/arch/riscv/kernel/Makefile > > +++ b/arch/riscv/kernel/Makefile > > @@ -32,6 +32,10 @@ obj-y += patch.o > > obj-$(CONFIG_MMU) += vdso.o vdso/ > > > > obj-$(CONFIG_RISCV_M_MODE) += clint.o traps_misaligned.o > > +OBJCOPYFLAGS := --prefix-symbols=__efistub_ > > +$(obj)/%.stub.o: $(obj)/%.o FORCE > > + $(call if_changed,objcopy) > > + > > obj-$(CONFIG_FPU) += fpu.o > > obj-$(CONFIG_SMP) += smpboot.o > > obj-$(CONFIG_SMP) += smp.o > > diff --git a/arch/riscv/kernel/efi-header.S > > b/arch/riscv/kernel/efi-header.S > > new file mode 100644 > > index 000000000000..69dde8268527 > > --- /dev/null > > +++ b/arch/riscv/kernel/efi-header.S > > @@ -0,0 +1,99 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > +/* > > + * Copyright (C) 2020 Western Digital Corporation or its > > affiliates. > > + * Adapted from arch/arm64/kernel/efi-header.S > > + */ > > + > > +#include <linux/pe.h> > > +#include <linux/sizes.h> > > + > > + .macro __EFI_PE_HEADER > > + .long PE_MAGIC > > +coff_header: > > + .short IMAGE_FILE_MACHINE_RISCV64 // Machine > > + .short section_count // > > NumberOfSections > > + .long 0 // > > TimeDateStamp > > + .long 0 // > > PointerToSymbolTable > > + .long 0 // > > NumberOfSymbols > > + .short section_table - optional_header // > > SizeOfOptionalHeader > > + .short IMAGE_FILE_DEBUG_STRIPPED | \ > > + IMAGE_FILE_EXECUTABLE_IMAGE | \ > > + IMAGE_FILE_LINE_NUMS_STRIPPED // > > Characteristics > > + > > +optional_header: > > + .short PE_OPT_MAGIC_PE32PLUS // PE32+ > > format > > + .byte 0x02 // > > MajorLinkerVersion > > + .byte 0x14 // > > MinorLinkerVersion > > + .long __text_end - efi_header_end // > > SizeOfCode > > + .long _end - __text_end // > > SizeOfInitializedData > > + .long 0 // > > SizeOfUninitializedData > > + .long __efistub_efi_entry - _start // > > AddressOfEntryPoint > > + .long efi_header_end - _start // > > BaseOfCode > > + > > +extra_header_fields: > > + .quad 0 // > > ImageBase > > + .long SZ_4K // > > SectionAlignment > > + .long PECOFF_FILE_ALIGNMENT // > > 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 - _start // > > SizeOfImage > > + > > + // Everything before the kernel image is considered part of the > > header > > + .long efi_header_end - _start // > > 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 (section_table - .) / 8 // > > NumberOfRvaAndSizes > > + > > + .quad 0 // > > ExportTable > > + .quad 0 // > > ImportTable > > + .quad 0 // > > ResourceTable > > + .quad 0 // > > ExceptionTable > > + .quad 0 // > > CertificationTable > > + .quad 0 // > > BaseRelocationTable > > + > > + // Section table > > +section_table: > > + .ascii ".text\0\0\0" > > + .long __text_end - efi_header_end // > > VirtualSize > > + .long efi_header_end - _start // > > VirtualAddress > > + .long __text_end - efi_header_end // > > SizeOfRawData > > + .long efi_header_end - _start // > > 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 __data_virt_size // > > VirtualSize > > + .long __text_end - _start // > > VirtualAddress > > + .long __data_raw_size // > > SizeOfRawData > > + .long __text_end - _start // > > 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 section_count, (. - section_table) / 40 > > + > > +efi_header_end: > > + .endm > > diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S > > index 98a406474e7d..ddd613dac9d6 100644 > > --- a/arch/riscv/kernel/head.S > > +++ b/arch/riscv/kernel/head.S > > @@ -13,6 +13,7 @@ > > #include <asm/csr.h> > > #include <asm/hwcap.h> > > #include <asm/image.h> > > +#include "efi-header.S" > > > > __HEAD > > ENTRY(_start) > > @@ -22,10 +23,18 @@ ENTRY(_start) > > * Do not modify it without modifying the structure and all > > bootloaders > > * that expects this header format!! > > */ > > +#ifdef CONFIG_EFI > > + /* > > + * This instruction decodes to "MZ" ASCII required by UEFI. > > + */ > > + li s4,-13 > > This needs to be a c.li in order to encode as "MZ". It'd be cleaner > to > explicitly write it that way rather that having the assembler > transparently > compress it, but we definately need to have Kconfig make EFI select > ISA_C. > Sure. I will add that. > > + j _start_kernel > > +#else > > /* jump to start kernel */ > > j _start_kernel > > /* reserved */ > > .word 0 > > +#endif > > .balign 8 > > #if __riscv_xlen == 64 > > /* Image load offset(2MB) from start of RAM */ > > @@ -43,7 +52,14 @@ ENTRY(_start) > > .ascii RISCV_IMAGE_MAGIC > > .balign 4 > > .ascii RISCV_IMAGE_MAGIC2 > > +#ifdef CONFIG_EFI > > + .word pe_head_start - _start > > +pe_head_start: > > + > > + __EFI_PE_HEADER > > +#else > > .word 0 > > +#endif > > > > .align 2 > > #ifdef CONFIG_MMU > > diff --git a/arch/riscv/kernel/image-vars.h > > b/arch/riscv/kernel/image-vars.h > > new file mode 100644 > > index 000000000000..bd8b764f0ad9 > > --- /dev/null > > +++ b/arch/riscv/kernel/image-vars.h > > @@ -0,0 +1,53 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > +/* > > + * Copyright (C) 2020 Western Digital Corporation or its > > affiliates. > > + * Linker script variables to be set after section resolution, as > > + * ld.lld does not like variables assigned before SECTIONS is > > processed. > > + * Based on arch/arm64/kerne/image-vars.h > > + */ > > +#ifndef __RISCV_KERNEL_IMAGE_VARS_H > > +#define __RISCV_KERNEL_IMAGE_VARS_H > > + > > +#ifndef LINKER_SCRIPT > > +#error This file should only be included in vmlinux.lds.S > > +#endif > > + > > +#ifdef CONFIG_EFI > > + > > +__efistub_stext_offset = _start_kernel - _start; > > + > > +/* > > + * The EFI stub has its own symbol namespace prefixed by > > __efistub_, to > > + * isolate it from the kernel proper. The following symbols are > > legally > > + * accessed by the stub, so provide some aliases to make them > > accessible. > > + * Only include data symbols here, or text symbols of functions > > that are > > + * guaranteed to be safe when executed at another offset than they > > were > > + * linked at. The routines below are all implemented in assembler > > in a > > + * position independent manner > > + */ > > +__efistub_memcmp = memcmp; > > +__efistub_memchr = memchr; > > +__efistub_memcpy = memcpy; > > +__efistub_memmove = memmove; > > +__efistub_memset = memset; > > +__efistub_strlen = strlen; > > +__efistub_strnlen = strnlen; > > +__efistub_strcmp = strcmp; > > +__efistub_strncmp = strncmp; > > +__efistub_strrchr = strrchr; > > + > > +#ifdef CONFIG_KASAN > > +__efistub___memcpy = memcpy; > > +__efistub___memmove = memmove; > > +__efistub___memset = memset; > > +#endif > > + > > +__efistub__start = _start; > > +__efistub__start_kernel = _start_kernel; > > +__efistub__end = _end; > > +__efistub__edata = _edata; > > +__efistub_screen_info = screen_info; > > + > > +#endif > > + > > +#endif /* __RISCV_KERNEL_IMAGE_VARS_H */ > > diff --git a/arch/riscv/kernel/vmlinux.lds.S > > b/arch/riscv/kernel/vmlinux.lds.S > > index 0339b6bbe11a..20ebf7e8c215 100644 > > --- a/arch/riscv/kernel/vmlinux.lds.S > > +++ b/arch/riscv/kernel/vmlinux.lds.S > > @@ -10,6 +10,7 @@ > > #include <asm/cache.h> > > #include <asm/thread_info.h> > > #include <asm/set_memory.h> > > +#include "image-vars.h" > > > > #include <linux/sizes.h> > > OUTPUT_ARCH(riscv) > > @@ -17,6 +18,14 @@ ENTRY(_start) > > > > jiffies = jiffies_64; > > > > +PECOFF_FILE_ALIGNMENT = 0x200; > > +#ifdef CONFIG_EFI > > +#define PECOFF_EDATA_PADDING \ > > + .pecoff_edata_padding : { BYTE(0); . = > > ALIGN(PECOFF_FILE_ALIGNMENT); } > > +#else > > +#define PECOFF_EDATA_PADDING > > +#endif > > + > > SECTIONS > > { > > /* Beginning of code and text segment */ > > @@ -62,6 +71,8 @@ SECTIONS > > _etext = .; > > } > > > > + __text_end = .; > > + > > /* Start of data section */ > > _sdata = .; > > RO_DATA(SECTION_ALIGN) > > @@ -78,9 +89,12 @@ SECTIONS > > .sdata : { > > __global_pointer$ = . + 0x800; > > *(.sdata*) > > - /* End of data section */ > > - _edata = .; > > } > > + PECOFF_EDATA_PADDING > > + __data_raw_size = ABSOLUTE(. - __text_end); > > + > > + /* End of data section */ > > + _edata = .; > > > > BSS_SECTION(PAGE_SIZE, PAGE_SIZE, 0) > > > > @@ -88,6 +102,8 @@ SECTIONS > > *(.rel.dyn*) > > } > > > > + __data_virt_size = ABSOLUTE(. - __text_end); > > + > > _end = .; > > > > STABS_DEBUG -- Regards, Atish