LXR linux/arch/arm64/kernel/image.h

   1/*
   2 * Linker script macros to generate Image header fields.
   3 *
   4 * Copyright (C) 2014 ARM Ltd.
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 *
  10 * This program is distributed in the hope that it will be useful,
  11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 * GNU General Public License for more details.
  14 *
  15 * You should have received a copy of the GNU General Public License
  16 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18#ifndef __ASM_IMAGE_H
  19#define __ASM_IMAGE_H
  20
  21#ifndef LINKER_SCRIPT
  22#error This file should only be included in vmlinux.lds.S
  23#endif
  24
  25/*
  26 * There aren't any ELF relocations we can use to endian-swap values known only
  27 * at link time (e.g. the subtraction of two symbol addresses), so we must get
  28 * the linker to endian-swap certain values before emitting them.
  29 *
  30 * Note that, in order for this to work when building the ELF64 PIE executable
  31 * (for KASLR), these values should not be referenced via R_AARCH64_ABS64
  32 * relocations, since these are fixed up at runtime rather than at build time
  33 * when PIE is in effect. So we need to split them up in 32-bit high and low
  34 * words.
  35 */
  36#ifdef CONFIG_CPU_BIG_ENDIAN
  37#define DATA_LE32(data)                         \
  38        ((((data) & 0x000000ff) << 24) |        \
  39         (((data) & 0x0000ff00) << 8)  |        \
  40         (((data) & 0x00ff0000) >> 8)  |        \
  41         (((data) & 0xff000000) >> 24))
  42#else
  43#define DATA_LE32(data) ((data) & 0xffffffff)
  44#endif
  45
  46#define DEFINE_IMAGE_LE64(sym, data)                            \
  47        sym##_lo32 = DATA_LE32((data) & 0xffffffff);            \
  48        sym##_hi32 = DATA_LE32((data) >> 32)
  49
  50#ifdef CONFIG_CPU_BIG_ENDIAN
  51#define __HEAD_FLAG_BE          1
  52#else
  53#define __HEAD_FLAG_BE          0
  54#endif
  55
  56#define __HEAD_FLAG_PAGE_SIZE   ((PAGE_SHIFT - 10) / 2)
  57
  58#define __HEAD_FLAG_PHYS_BASE   1
  59
  60#define __HEAD_FLAGS            ((__HEAD_FLAG_BE << 0) |        \
  61                                 (__HEAD_FLAG_PAGE_SIZE << 1) | \
  62                                 (__HEAD_FLAG_PHYS_BASE << 3))
  63
  64/*
  65 * These will output as part of the Image header, which should be little-endian
  66 * regardless of the endianness of the kernel. While constant values could be
  67 * endian swapped in head.S, all are done here for consistency.
  68 */
  69#define HEAD_SYMBOLS                                            \
  70        DEFINE_IMAGE_LE64(_kernel_size_le, _end - _text);       \
  71        DEFINE_IMAGE_LE64(_kernel_offset_le, TEXT_OFFSET);      \
  72        DEFINE_IMAGE_LE64(_kernel_flags_le, __HEAD_FLAGS);
  73
  74#ifdef CONFIG_EFI
  75
  76__efistub_stext_offset = stext - _text;
  77
  78/*
  79 * Prevent the symbol aliases below from being emitted into the kallsyms
  80 * table, by forcing them to be absolute symbols (which are conveniently
  81 * ignored by scripts/kallsyms) rather than section relative symbols.
  82 * The distinction is only relevant for partial linking, and only for symbols
  83 * that are defined within a section declaration (which is not the case for
  84 * the definitions below) so the resulting values will be identical.
  85 */
  86#define KALLSYMS_HIDE(sym)      ABSOLUTE(sym)
  87
  88/*
  89 * The EFI stub has its own symbol namespace prefixed by __efistub_, to
  90 * isolate it from the kernel proper. The following symbols are legally
  91 * accessed by the stub, so provide some aliases to make them accessible.
  92 * Only include data symbols here, or text symbols of functions that are
  93 * guaranteed to be safe when executed at another offset than they were
  94 * linked at. The routines below are all implemented in assembler in a
  95 * position independent manner
  96 */
  97__efistub_memcmp                = KALLSYMS_HIDE(__pi_memcmp);
  98__efistub_memchr                = KALLSYMS_HIDE(__pi_memchr);
  99__efistub_memcpy                = KALLSYMS_HIDE(__pi_memcpy);
 100__efistub_memmove               = KALLSYMS_HIDE(__pi_memmove);
 101__efistub_memset                = KALLSYMS_HIDE(__pi_memset);
 102__efistub_strlen                = KALLSYMS_HIDE(__pi_strlen);
 103__efistub_strnlen               = KALLSYMS_HIDE(__pi_strnlen);
 104__efistub_strcmp                = KALLSYMS_HIDE(__pi_strcmp);
 105__efistub_strncmp               = KALLSYMS_HIDE(__pi_strncmp);
 106__efistub_strrchr               = KALLSYMS_HIDE(__pi_strrchr);
 107__efistub___flush_dcache_area   = KALLSYMS_HIDE(__pi___flush_dcache_area);
 108
 109#ifdef CONFIG_KASAN
 110__efistub___memcpy              = KALLSYMS_HIDE(__pi_memcpy);
 111__efistub___memmove             = KALLSYMS_HIDE(__pi_memmove);
 112__efistub___memset              = KALLSYMS_HIDE(__pi_memset);
 113#endif
 114
 115__efistub__text                 = KALLSYMS_HIDE(_text);
 116__efistub__end                  = KALLSYMS_HIDE(_end);
 117__efistub__edata                = KALLSYMS_HIDE(_edata);
 118__efistub_screen_info           = KALLSYMS_HIDE(screen_info);
 119
 120#endif
 121
 122#endif /* __ASM_IMAGE_H */
 123