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Andrew Scullb4b6d4a2019-01-02 15:54:55 +00001/*
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 */