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214a87757a
While the _start label is only intended for use locally to populate the (hand-written) PE header, the linker script includes ENTRY(_start) which designates it as the entry point in the output ELF, resulting in linker warnings under some linkers (e.g. LLVM's lld) due to _start not being a globally-visible symbol. Since ELF is only an intermediary build format, and the aforementioned PE header correctly points to _start, the ENTRY(_start) directive could easily be removed to silence this warning. However, since some developers who are debugging EFI by analyzing the intermediary ELF may appreciate having correct entry-point information, this patch instead promotes the _start labels to global symbols, silencing the linker warning and making the intermediary ELF reflect the true entry point. This patch doesn't affect the final output binaries in any way. Signed-off-by: Sam Edwards <CFSworks@gmail.com>
165 lines
4.6 KiB
ArmAsm
165 lines
4.6 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0+ OR BSD-2-Clause */
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/*
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* crt0-efi-arm.S - PE/COFF header for ARM EFI applications
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*
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* Copright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
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*
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* This file is taken and modified from the gnu-efi project.
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*/
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#include <asm-generic/pe.h>
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.section .text.head
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/*
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* Magic "MZ" signature for PE/COFF
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*/
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.globl image_base
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image_base:
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.short IMAGE_DOS_SIGNATURE /* 'MZ' */
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.skip 58 /* 'MZ' + pad + offset == 64 */
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.long pe_header - image_base /* Offset to the PE header */
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pe_header:
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.long IMAGE_NT_SIGNATURE /* 'PE' */
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coff_header:
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.short IMAGE_FILE_MACHINE_THUMB /* Mixed ARM/Thumb */
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.short 3 /* nr_sections */
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.long 0 /* TimeDateStamp */
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.long 0 /* PointerToSymbolTable */
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.long 0 /* NumberOfSymbols */
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.short section_table - optional_header /* SizeOfOptionalHeader */
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/* Characteristics */
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.short (IMAGE_FILE_EXECUTABLE_IMAGE | \
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IMAGE_FILE_LINE_NUMS_STRIPPED | \
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IMAGE_FILE_LOCAL_SYMS_STRIPPED | \
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IMAGE_FILE_32BIT_MACHINE | \
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IMAGE_FILE_DEBUG_STRIPPED)
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optional_header:
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.short IMAGE_NT_OPTIONAL_HDR32_MAGIC /* PE32 format */
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.byte 0x02 /* MajorLinkerVersion */
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.byte 0x14 /* MinorLinkerVersion */
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.long _etext - _start /* SizeOfCode */
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.long _data_size /* SizeOfInitializedData */
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.long 0 /* SizeOfUninitializedData */
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.long _start - image_base /* AddressOfEntryPoint */
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.long _start - image_base /* BaseOfCode */
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.long 0 /* BaseOfData */
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extra_header_fields:
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.long 0 /* ImageBase */
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.long 0x1000 /* SectionAlignment */
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.long 0x200 /* FileAlignment */
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.short 0 /* MajorOperatingSystemVersion */
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.short 0 /* MinorOperatingSystemVersion */
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.short 0 /* MajorImageVersion */
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.short 0 /* MinorImageVersion */
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.short 0 /* MajorSubsystemVersion */
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.short 0 /* MinorSubsystemVersion */
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.long 0 /* Win32VersionValue */
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.long _edata - image_base /* SizeOfImage */
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/*
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* Everything before the kernel image is considered part of the header
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*/
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.long _start - image_base /* SizeOfHeaders */
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.long 0 /* CheckSum */
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.short IMAGE_SUBSYSTEM_EFI_APPLICATION /* Subsystem */
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#if CONFIG_VENDOR_EFI
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.short 0 /* DllCharacteristics */
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#else
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.short IMAGE_DLLCHARACTERISTICS_NX_COMPAT
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#endif
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.long 0 /* SizeOfStackReserve */
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.long 0 /* SizeOfStackCommit */
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.long 0 /* SizeOfHeapReserve */
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.long 0 /* SizeOfHeapCommit */
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.long 0 /* LoaderFlags */
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.long 0x6 /* NumberOfRvaAndSizes */
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.quad 0 /* ExportTable */
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.quad 0 /* ImportTable */
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.quad 0 /* ResourceTable */
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.quad 0 /* ExceptionTable */
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.quad 0 /* CertificationTable */
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.quad 0 /* BaseRelocationTable */
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/* Section table */
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section_table:
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/*
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* The EFI application loader requires a relocation section
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* because EFI applications must be relocatable. This is a
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* dummy section as far as we are concerned.
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*/
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.ascii ".reloc"
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.byte 0
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.byte 0 /* end of 0 padding of section name */
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.long 0
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.long 0
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.long 0 /* SizeOfRawData */
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.long 0 /* PointerToRawData */
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.long 0 /* PointerToRelocations */
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.long 0 /* PointerToLineNumbers */
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.short 0 /* NumberOfRelocations */
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.short 0 /* NumberOfLineNumbers */
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/* Characteristics (section flags) */
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.long (IMAGE_SCN_MEM_READ | \
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IMAGE_SCN_MEM_DISCARDABLE | \
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IMAGE_SCN_CNT_INITIALIZED_DATA)
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.ascii ".text"
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.byte 0
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.byte 0
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.byte 0 /* end of 0 padding of section name */
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.long _etext - _start /* VirtualSize */
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.long _start - image_base /* VirtualAddress */
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.long _etext - _start /* SizeOfRawData */
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.long _start - image_base /* PointerToRawData */
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.long 0 /* PointerToRelocations */
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.long 0 /* PointerToLineNumbers */
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.short 0 /* NumberOfRelocations */
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.short 0 /* NumberOfLineNumbers */
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/* Characteristics (section flags) */
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.long (IMAGE_SCN_MEM_READ | \
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IMAGE_SCN_MEM_EXECUTE | \
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IMAGE_SCN_CNT_CODE)
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.ascii ".data"
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.byte 0
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.byte 0
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.byte 0 /* end of 0 padding of section name */
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.long _data_size /* VirtualSize */
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.long _data - image_base /* VirtualAddress */
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.long _data_size /* SizeOfRawData */
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.long _data - image_base /* PointerToRawData */
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.long 0 /* PointerToRelocations */
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.long 0 /* PointerToLineNumbers */
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.short 0 /* NumberOfRelocations */
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.short 0 /* NumberOfLineNumbers */
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/* Characteristics (section flags) */
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.long (IMAGE_SCN_MEM_WRITE | \
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IMAGE_SCN_MEM_READ | \
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IMAGE_SCN_CNT_INITIALIZED_DATA)
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.align 12
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.globl _start
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_start:
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stmfd sp!, {r0-r2, lr}
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adr r1, .L_DYNAMIC
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ldr r0, [r1]
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add r1, r0, r1
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adrl r0, image_base
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bl _relocate
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teq r0, #0
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bne 0f
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ldmfd sp, {r0-r1}
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bl efi_main
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0: add sp, sp, #12
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ldr pc, [sp], #4
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.L_DYNAMIC:
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.word _DYNAMIC - .
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