arch/arm64/kernel/image.h

   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 #ifdef CONFIG_EFI
  69
  70 /*
  71  * Use ABSOLUTE() to avoid ld.lld treating this as a relative symbol:
  72  * https://github.com/ClangBuiltLinux/linux/issues/561
  73  */
  74 __efistub_stext_offset = ABSOLUTE(stext - _text);
  75
  76 /*
  77  * The EFI stub has its own symbol namespace prefixed by __efistub_, to
  78  * isolate it from the kernel proper. The following symbols are legally
  79  * accessed by the stub, so provide some aliases to make them accessible.
  80  * Only include data symbols here, or text symbols of functions that are
  81  * guaranteed to be safe when executed at another offset than they were
  82  * linked at. The routines below are all implemented in assembler in a
  83  * position independent manner
  84  */
  85 __efistub_memcmp                = __pi_memcmp;
  86 __efistub_memchr                = __pi_memchr;
  87 __efistub_memcpy                = __pi_memcpy;
  88 __efistub_memmove               = __pi_memmove;
  89 __efistub_memset                = __pi_memset;
  90 __efistub_strlen                = __pi_strlen;
  91 __efistub_strnlen               = __pi_strnlen;
  92 __efistub_strcmp                = __pi_strcmp;
  93 __efistub_strncmp               = __pi_strncmp;
  94 __efistub_strrchr               = __pi_strrchr;
  95 __efistub___flush_dcache_area   = __pi___flush_dcache_area;
  96
  97 #ifdef CONFIG_KASAN
  98 __efistub___memcpy              = __pi_memcpy;
  99 __efistub___memmove             = __pi_memmove;
 100 __efistub___memset              = __pi_memset;
 101 #endif
 102
 103 __efistub__text                 = _text;
 104 __efistub__end                  = _end;
 105 __efistub__edata                = _edata;
 106 __efistub_screen_info           = screen_info;
 107
 108 #endif
 109
 110 #endif /* __ARM64_KERNEL_IMAGE_H */