root/arch/arm64/kernel/image.h

INCLUDED FROM

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Linker script macros to generate Image header fields.
   4  *
   5  * Copyright (C) 2014 ARM Ltd.
   6  */
   7 #ifndef __ARM64_KERNEL_IMAGE_H
   8 #define __ARM64_KERNEL_IMAGE_H
   9 
  10 #ifndef LINKER_SCRIPT
  11 #error This file should only be included in vmlinux.lds.S
  12 #endif
  13 
  14 #include <asm/image.h>
  15 
  16 /*
  17  * There aren't any ELF relocations we can use to endian-swap values known only
  18  * at link time (e.g. the subtraction of two symbol addresses), so we must get
  19  * the linker to endian-swap certain values before emitting them.
  20  *
  21  * Note that, in order for this to work when building the ELF64 PIE executable
  22  * (for KASLR), these values should not be referenced via R_AARCH64_ABS64
  23  * relocations, since these are fixed up at runtime rather than at build time
  24  * when PIE is in effect. So we need to split them up in 32-bit high and low
  25  * words.
  26  */
  27 #ifdef CONFIG_CPU_BIG_ENDIAN
  28 #define DATA_LE32(data)                         \
  29         ((((data) & 0x000000ff) << 24) |        \
  30          (((data) & 0x0000ff00) << 8)  |        \
  31          (((data) & 0x00ff0000) >> 8)  |        \
  32          (((data) & 0xff000000) >> 24))
  33 #else
  34 #define DATA_LE32(data) ((data) & 0xffffffff)
  35 #endif
  36 
  37 #define DEFINE_IMAGE_LE64(sym, data)                            \
  38         sym##_lo32 = DATA_LE32((data) & 0xffffffff);            \
  39         sym##_hi32 = DATA_LE32((data) >> 32)
  40 
  41 #define __HEAD_FLAG(field)      (__HEAD_FLAG_##field << \
  42                                         ARM64_IMAGE_FLAG_##field##_SHIFT)
  43 
  44 #ifdef CONFIG_CPU_BIG_ENDIAN
  45 #define __HEAD_FLAG_BE          ARM64_IMAGE_FLAG_BE
  46 #else
  47 #define __HEAD_FLAG_BE          ARM64_IMAGE_FLAG_LE
  48 #endif
  49 
  50 #define __HEAD_FLAG_PAGE_SIZE   ((PAGE_SHIFT - 10) / 2)
  51 
  52 #define __HEAD_FLAG_PHYS_BASE   1
  53 
  54 #define __HEAD_FLAGS            (__HEAD_FLAG(BE)        | \
  55                                  __HEAD_FLAG(PAGE_SIZE) | \
  56                                  __HEAD_FLAG(PHYS_BASE))
  57 
  58 /*
  59  * These will output as part of the Image header, which should be little-endian
  60  * regardless of the endianness of the kernel. While constant values could be
  61  * endian swapped in head.S, all are done here for consistency.
  62  */
  63 #define HEAD_SYMBOLS                                            \
  64         DEFINE_IMAGE_LE64(_kernel_size_le, _end - _text);       \
  65         DEFINE_IMAGE_LE64(_kernel_offset_le, TEXT_OFFSET);      \
  66         DEFINE_IMAGE_LE64(_kernel_flags_le, __HEAD_FLAGS);
  67 
  68 #endif /* __ARM64_KERNEL_IMAGE_H */