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https://github.com/AsahiLinux/u-boot
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ARMv8: add optional Linux kernel image header
Allow placing a Linux kernel image header at the start of the U-Boot binary. This is useful since the image header reports the amount of memory (BSS and similar) that U-Boot needs to use, but that isn't part of the binary size. This can be used by the code that loads U-Boot into memory to determine where to load U-Boot, based on other users of memory. Signed-off-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Tom Warren <twarren@nvidia.com>
This commit is contained in:
Stephen Warren
Tom Warren
parent
f097532d27
commit
8163faf952
5 changed files with 159 additions and 1 deletions
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@ -32,6 +32,23 @@ config SYS_INIT_SP_BSS_OFFSET
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calculate the stack pointer. This offset should be large enough so
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that the early malloc region, global data (gd), and early stack usage
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do not overlap any appended DTB.
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config LINUX_KERNEL_IMAGE_HEADER
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bool
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help
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Place a Linux kernel image header at the start of the U-Boot binary.
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The format of the header is described in the Linux kernel source at
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Documentation/arm64/booting.txt. This feature is useful since the
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image header reports the amount of memory (BSS and similar) that
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U-Boot needs to use, but which isn't part of the binary.
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if LINUX_KERNEL_IMAGE_HEADER
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config LNX_KRNL_IMG_TEXT_OFFSET_BASE
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hex
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help
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The value subtracted from CONFIG_SYS_TEXT_BASE to calculate the
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TEXT_OFFSET value written in to the Linux kernel image header.
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endif
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endif
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config STATIC_RELA
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86
arch/arm/cpu/armv8/linux-kernel-image-header-vars.h
Normal file
86
arch/arm/cpu/armv8/linux-kernel-image-header-vars.h
Normal file
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@ -0,0 +1,86 @@
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/*
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* (C) Copyright 2017 NVIDIA Corporation <www.nvidia.com>
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*
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* Derived from Linux kernel v4.14 files:
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*
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* arch/arm64/include/asm/assembler.h:
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* Based on arch/arm/include/asm/assembler.h, arch/arm/mm/proc-macros.S
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* Copyright (C) 1996-2000 Russell King
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* Copyright (C) 2012 ARM Ltd.
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*
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* arch/arm64/kernel/head.S:
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* Based on arch/arm/kernel/head.S
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* Copyright (C) 1994-2002 Russell King
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* Copyright (C) 2003-2012 ARM Ltd.
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* Authors: Catalin Marinas <catalin.marinas@arm.com>
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* Will Deacon <will.deacon@arm.com>
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*
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* arch/arm64/kernel/image.h:
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* Copyright (C) 2014 ARM Ltd.
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*
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* SPDX-License-Identifier: GPL-2.0
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*/
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/*
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* There aren't any ELF relocations we can use to endian-swap values known only
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* at link time (e.g. the subtraction of two symbol addresses), so we must get
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* the linker to endian-swap certain values before emitting them.
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*
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* Note that, in order for this to work when building the ELF64 PIE executable
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* (for KASLR), these values should not be referenced via R_AARCH64_ABS64
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* relocations, since these are fixed up at runtime rather than at build time
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* when PIE is in effect. So we need to split them up in 32-bit high and low
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* words.
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*/
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#ifdef CONFIG_CPU_BIG_ENDIAN
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#define DATA_LE32(data) \
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((((data) & 0x000000ff) << 24) | \
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(((data) & 0x0000ff00) << 8) | \
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(((data) & 0x00ff0000) >> 8) | \
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(((data) & 0xff000000) >> 24))
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#else
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#define DATA_LE32(data) ((data) & 0xffffffff)
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#endif
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#define DEFINE_IMAGE_LE64(sym, data) \
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sym##_lo32 = DATA_LE32((data) & 0xffffffff); \
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sym##_hi32 = DATA_LE32((data) >> 32)
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#define __MAX(a, b) (((a) > (b)) ? (a) : (b))
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#define __CODE_DATA_SIZE (__bss_start - _start)
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#define __BSS_SIZE (__bss_end - __bss_start)
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#ifdef CONFIG_SYS_INIT_SP_BSS_OFFSET
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#define __MAX_EXTRA_RAM_USAGE __MAX(__BSS_SIZE, CONFIG_SYS_INIT_SP_BSS_OFFSET)
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#else
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#define __MAX_EXTRA_RAM_USAGE __BSS_SIZE
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#endif
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#define __MEM_USAGE (__CODE_DATA_SIZE + __MAX_EXTRA_RAM_USAGE)
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#ifdef CONFIG_CPU_BIG_ENDIAN
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#define __HEAD_FLAG_BE 1
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#else
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#define __HEAD_FLAG_BE 0
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#endif
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#define __HEAD_FLAG_PAGE_SIZE 1 /* 4K hard-coded */
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#define __HEAD_FLAG_PHYS_BASE 1
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#define __HEAD_FLAGS ((__HEAD_FLAG_BE << 0) | \
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(__HEAD_FLAG_PAGE_SIZE << 1) | \
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(__HEAD_FLAG_PHYS_BASE << 3))
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#define TEXT_OFFSET (CONFIG_SYS_TEXT_BASE - \
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CONFIG_LNX_KRNL_IMG_TEXT_OFFSET_BASE)
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/*
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* These will output as part of the Image header, which should be little-endian
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* regardless of the endianness of the kernel. While constant values could be
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* endian swapped in head.S, all are done here for consistency.
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*/
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#define HEAD_SYMBOLS \
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DEFINE_IMAGE_LE64(_kernel_size_le, __MEM_USAGE); \
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DEFINE_IMAGE_LE64(_kernel_offset_le, TEXT_OFFSET); \
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DEFINE_IMAGE_LE64(_kernel_flags_le, __HEAD_FLAGS);
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HEAD_SYMBOLS
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@ -19,7 +19,9 @@
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.globl _start
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_start:
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#ifdef CONFIG_ENABLE_ARM_SOC_BOOT0_HOOK
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#if defined(LINUX_KERNEL_IMAGE_HEADER)
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#include <asm/boot0-linux-kernel-header.h>
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#elif defined(CONFIG_ENABLE_ARM_SOC_BOOT0_HOOK)
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/*
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* Various SoCs need something special and SoC-specific up front in
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* order to boot, allow them to set that in their boot0.h file and then
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@ -159,4 +159,8 @@ SECTIONS
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/DISCARD/ : { *(.plt*) }
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/DISCARD/ : { *(.interp*) }
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/DISCARD/ : { *(.gnu*) }
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#ifdef CONFIG_LINUX_KERNEL_IMAGE_HEADER
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#include "linux-kernel-image-header-vars.h"
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#endif
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}
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49
arch/arm/include/asm/boot0-linux-kernel-header.h
Normal file
49
arch/arm/include/asm/boot0-linux-kernel-header.h
Normal file
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@ -0,0 +1,49 @@
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/*
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* (C) Copyright 2017 NVIDIA Corporation <www.nvidia.com>
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*
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* Derived from Linux kernel v4.14 files:
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*
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* arch/arm64/include/asm/assembler.h:
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* Based on arch/arm/include/asm/assembler.h, arch/arm/mm/proc-macros.S
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* Copyright (C) 1996-2000 Russell King
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* Copyright (C) 2012 ARM Ltd.
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*
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* arch/arm64/kernel/head.S:
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* Based on arch/arm/kernel/head.S
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* Copyright (C) 1994-2002 Russell King
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* Copyright (C) 2003-2012 ARM Ltd.
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* Authors: Catalin Marinas <catalin.marinas@arm.com>
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* Will Deacon <will.deacon@arm.com>
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*
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* arch/arm64/kernel/image.h:
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* Copyright (C) 2014 ARM Ltd.
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*
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* SPDX-License-Identifier: GPL-2.0
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*/
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/*
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* Emit a 64-bit absolute little endian symbol reference in a way that
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* ensures that it will be resolved at build time, even when building a
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* PIE binary. This requires cooperation from the linker script, which
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* must emit the lo32/hi32 halves individually.
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*/
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.macro le64sym, sym
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.long \sym\()_lo32
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.long \sym\()_hi32
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.endm
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.globl _start
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_start:
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/*
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* DO NOT MODIFY. Image header expected by Linux boot-loaders.
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*/
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b reset /* branch to kernel start, magic */
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.long 0 /* reserved */
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le64sym _kernel_offset_le /* Image load offset from start of RAM, little-endian */
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le64sym _kernel_size_le /* Effective size of kernel image, little-endian */
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le64sym _kernel_flags_le /* Informative flags, little-endian */
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.quad 0 /* reserved */
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.quad 0 /* reserved */
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.quad 0 /* reserved */
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.ascii "ARM\x64" /* Magic number */
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.long 0 /* reserved */
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