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___flush_dcache_area = KALLSYMS_HIDE(__pi___flush_dcache_area); 107 108 #ifdef CONFIG_KASAN 109 __efistub___memcpy = KALLSYMS_HIDE(__pi_memcpy); 110 __efistub___memmove = KALLSYMS_HIDE(__pi_memmove); 111 __efistub___memset = KALLSYMS_HIDE(__pi_memset); 112 #endif 113 114 __efistub__text = KALLSYMS_HIDE(_text); 115 __efistub__end = KALLSYMS_HIDE(_end); 116 __efistub__edata = KALLSYMS_HIDE(_edata); 117 __efistub_screen_info = KALLSYMS_HIDE(screen_info); 118 119 #endif 120 121 #endif /* __ASM_IMAGE_H */ 122