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 #ifdef CONFIG_CPU_BIG_ENDIAN
  31 #define DATA_LE64(data)                                 \
  32         ((((data) & 0x00000000000000ff) << 56) |        \
  33          (((data) & 0x000000000000ff00) << 40) |        \
  34          (((data) & 0x0000000000ff0000) << 24) |        \
  35          (((data) & 0x00000000ff000000) << 8)  |        \
  36          (((data) & 0x000000ff00000000) >> 8)  |        \
  37          (((data) & 0x0000ff0000000000) >> 24) |        \
  38          (((data) & 0x00ff000000000000) >> 40) |        \
  39          (((data) & 0xff00000000000000) >> 56))
  40 #else
  41 #define DATA_LE64(data) ((data) & 0xffffffffffffffff)
  42 #endif
  43
  44 #ifdef CONFIG_CPU_BIG_ENDIAN
  45 #define __HEAD_FLAG_BE  1
  46 #else
  47 #define __HEAD_FLAG_BE  0
  48 #endif
  49
  50 #define __HEAD_FLAG_PAGE_SIZE ((PAGE_SHIFT - 10) / 2)
  51
  52 #define __HEAD_FLAGS    ((__HEAD_FLAG_BE << 0) |        \
  53                          (__HEAD_FLAG_PAGE_SIZE << 1))
  54
  55 /*
  56  * These will output as part of the Image header, which should be little-endian
  57  * regardless of the endianness of the kernel. While constant values could be
  58  * endian swapped in head.S, all are done here for consistency.
  59  */
  60 #define HEAD_SYMBOLS                                            \
  61         _kernel_size_le         = DATA_LE64(_end - _text);      \
  62         _kernel_offset_le       = DATA_LE64(TEXT_OFFSET);       \
  63         _kernel_flags_le        = DATA_LE64(__HEAD_FLAGS);
  64
  65 #ifdef CONFIG_EFI
  66
  67 /*
  68  * Prevent the symbol aliases below from being emitted into the kallsyms
  69  * table, by forcing them to be absolute symbols (which are conveniently
  70  * ignored by scripts/kallsyms) rather than section relative symbols.
  71  * The distinction is only relevant for partial linking, and only for symbols
  72  * that are defined within a section declaration (which is not the case for
  73  * the definitions below) so the resulting values will be identical.
  74  */
  75 #define KALLSYMS_HIDE(sym)      ABSOLUTE(sym)
  76
  77 /*
  78  * The EFI stub has its own symbol namespace prefixed by __efistub_, to
  79  * isolate it from the kernel proper. The following symbols are legally
  80  * accessed by the stub, so provide some aliases to make them accessible.
  81  * Only include data symbols here, or text symbols of functions that are
  82  * guaranteed to be safe when executed at another offset than they were
  83  * linked at. The routines below are all implemented in assembler in a
  84  * position independent manner
  85  */
  86 __efistub_memcmp                = KALLSYMS_HIDE(__pi_memcmp);
  87 __efistub_memchr                = KALLSYMS_HIDE(__pi_memchr);
  88 __efistub_memcpy                = KALLSYMS_HIDE(__pi_memcpy);
  89 __efistub_memmove               = KALLSYMS_HIDE(__pi_memmove);
  90 __efistub_memset                = KALLSYMS_HIDE(__pi_memset);
  91 __efistub_strlen                = KALLSYMS_HIDE(__pi_strlen);
  92 __efistub_strnlen               = KALLSYMS_HIDE(__pi_strnlen);
  93 __efistub_strcmp                = KALLSYMS_HIDE(__pi_strcmp);
  94 __efistub_strncmp               = KALLSYMS_HIDE(__pi_strncmp);
  95 __efistub___flush_dcache_area   = KALLSYMS_HIDE(__pi___flush_dcache_area);
  96
  97 #ifdef CONFIG_KASAN
  98 __efistub___memcpy              = KALLSYMS_HIDE(__pi_memcpy);
  99 __efistub___memmove             = KALLSYMS_HIDE(__pi_memmove);
 100 __efistub___memset              = KALLSYMS_HIDE(__pi_memset);
 101 #endif
 102
 103 __efistub__text                 = KALLSYMS_HIDE(_text);
 104 __efistub__end                  = KALLSYMS_HIDE(_end);
 105 __efistub__edata                = KALLSYMS_HIDE(_edata);
 106
 107 #endif
 108
 109 #endif /* __ASM_IMAGE_H */