On Tue, Aug 25, 2020 at 11:04 AM Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote: > > On Wed, 19 Aug 2020 15:24:21 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> > > Link: https://lore.kernel.org/r/20200421033336.9663-3-atish.patra@xxxxxxx > > [ardb: - use C prefix for c.li to ensure the expected opcode is emitted > > - align all image sections according to PE/COFF section alignment ] > > Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > > Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx> > > --- > > arch/riscv/include/asm/sections.h | 13 ++++ > > arch/riscv/kernel/Makefile | 4 ++ > > arch/riscv/kernel/efi-header.S | 104 ++++++++++++++++++++++++++++++ > > arch/riscv/kernel/head.S | 16 +++++ > > arch/riscv/kernel/image-vars.h | 51 +++++++++++++++ > > arch/riscv/kernel/vmlinux.lds.S | 22 ++++++- > > 6 files changed, 208 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 a5287ab9f7f2..eabec4dce50b 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 > > + $(call if_changed,objcopy) > > + > > Is there a reason this is below those objects? Nope. I don't really care, but it > triggered a merge conflict and it seems cleaner above so I put it up there. > Sure. Thanks. > > obj-$(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..822b4c9ff2bb > > --- /dev/null > > +++ b/arch/riscv/kernel/efi-header.S > > @@ -0,0 +1,104 @@ > > +/* 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: > > +#ifdef CONFIG_64BIT > > + .short IMAGE_FILE_MACHINE_RISCV64 // Machine > > +#else > > + .short IMAGE_FILE_MACHINE_RISCV32 // Machine > > +#endif > > + .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 __pecoff_text_end - efi_header_end // SizeOfCode > > + .long __pecoff_data_virt_size // SizeOfInitializedData > > + .long 0 // SizeOfUninitializedData > > + .long __efistub_efi_pe_entry - _start // AddressOfEntryPoint > > + .long efi_header_end - _start // BaseOfCode > > + > > +extra_header_fields: > > + .quad 0 // ImageBase > > + .long PECOFF_SECTION_ALIGNMENT // 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 __pecoff_text_end - efi_header_end // VirtualSize > > + .long efi_header_end - _start // VirtualAddress > > + .long __pecoff_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 __pecoff_data_virt_size // VirtualSize > > + .long __pecoff_text_end - _start // VirtualAddress > > + .long __pecoff_data_raw_size // SizeOfRawData > > + .long __pecoff_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 > > + > > + .balign 0x1000 > > +efi_header_end: > > + .endm > > diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S > > index c6a37e8231a8..3631147732ee 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. > > + */ > > + c.li s4,-13 > > + 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..8c212efb37a6 > > --- /dev/null > > +++ b/arch/riscv/kernel/image-vars.h > > @@ -0,0 +1,51 @@ > > +/* 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 > > + > > +/* > > + * 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 f3586e31ed1e..6dcf790282dd 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 +18,9 @@ ENTRY(_start) > > > > jiffies = jiffies_64; > > > > +PECOFF_SECTION_ALIGNMENT = 0x1000; > > +PECOFF_FILE_ALIGNMENT = 0x200; > > + > > SECTIONS > > { > > /* Beginning of code and text segment */ > > @@ -76,6 +80,10 @@ SECTIONS > > > > EXCEPTION_TABLE(0x10) > > > > +#ifdef CONFIG_EFI > > + . = ALIGN(PECOFF_SECTION_ALIGNMENT); > > + __pecoff_text_end = .; > > +#endif > > . = ALIGN(SECTION_ALIGN); > > _data = .; > > > > @@ -83,16 +91,26 @@ SECTIONS > > .sdata : { > > __global_pointer$ = . + 0x800; > > *(.sdata*) > > - /* End of data section */ > > - _edata = .; > > } > > > > +#ifdef CONFIG_EFI > > + .pecoff_edata_padding : { BYTE(0); . = ALIGN(PECOFF_FILE_ALIGNMENT); } > > + __pecoff_data_raw_size = ABSOLUTE(. - __pecoff_text_end); > > +#endif > > + > > + /* End of data section */ > > + _edata = .; > > + > > BSS_SECTION(PAGE_SIZE, PAGE_SIZE, 0) > > > > .rel.dyn : { > > *(.rel.dyn*) > > } > > > > +#ifdef CONFIG_EFI > > + . = ALIGN(PECOFF_SECTION_ALIGNMENT); > > + __pecoff_data_virt_size = ABSOLUTE(. - __pecoff_text_end); > > +#endif > > _end = .; > > > > STABS_DEBUG -- Regards, Atish
