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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_POWERPC_HEAD_64_H
3#define _ASM_POWERPC_HEAD_64_H
4
5#include <asm/cache.h>
6
7#ifdef __ASSEMBLY__
8/*
9 * We can't do CPP stringification and concatination directly into the section
10 * name for some reason, so these macros can do it for us.
11 */
12.macro define_ftsec name
13 .section ".head.text.\name\()","ax",@progbits
14.endm
15.macro define_data_ftsec name
16 .section ".head.data.\name\()","a",@progbits
17.endm
18.macro use_ftsec name
19 .section ".head.text.\name\()"
20.endm
21
22/*
23 * Fixed (location) sections are used by opening fixed sections and emitting
24 * fixed section entries into them before closing them. Multiple fixed sections
25 * can be open at any time.
26 *
27 * Each fixed section created in a .S file must have corresponding linkage
28 * directives including location, added to arch/powerpc/kernel/vmlinux.lds.S
29 *
30 * For each fixed section, code is generated into it in the order which it
31 * appears in the source. Fixed section entries can be placed at a fixed
32 * location within the section using _LOCATION postifx variants. These must
33 * be ordered according to their relative placements within the section.
34 *
35 * OPEN_FIXED_SECTION(section_name, start_address, end_address)
36 * FIXED_SECTION_ENTRY_BEGIN(section_name, label1)
37 *
38 * USE_FIXED_SECTION(section_name)
39 * label3:
40 * li r10,128
41 * mv r11,r10
42
43 * FIXED_SECTION_ENTRY_BEGIN_LOCATION(section_name, label2, start_address, size)
44 * FIXED_SECTION_ENTRY_END_LOCATION(section_name, label2, start_address, size)
45 * CLOSE_FIXED_SECTION(section_name)
46 *
47 * ZERO_FIXED_SECTION can be used to emit zeroed data.
48 *
49 * Troubleshooting:
50 * - If the build dies with "Error: attempt to move .org backwards" at
51 * CLOSE_FIXED_SECTION() or elsewhere, there may be something
52 * unexpected being added there. Remove the '. = x_len' line, rebuild, and
53 * check what is pushing the section down.
54 * - If the build dies in linking, check arch/powerpc/tools/head_check.sh
55 * comments.
56 * - If the kernel crashes or hangs in very early boot, it could be linker
57 * stubs at the start of the main text.
58 */
59
60#define OPEN_FIXED_SECTION(sname, start, end) \
61 sname##_start = (start); \
62 sname##_end = (end); \
63 sname##_len = (end) - (start); \
64 define_ftsec sname; \
65 . = 0x0; \
66start_##sname:
67
68/*
69 * .linker_stub_catch section is used to catch linker stubs from being
70 * inserted in our .text section, above the start_text label (which breaks
71 * the ABS_ADDR calculation). See kernel/vmlinux.lds.S and tools/head_check.sh
72 * for more details. We would prefer to just keep a cacheline (0x80), but
73 * 0x100 seems to be how the linker aligns branch stub groups.
74 */
75#ifdef CONFIG_LD_HEAD_STUB_CATCH
76#define OPEN_TEXT_SECTION(start) \
77 .section ".linker_stub_catch","ax",@progbits; \
78linker_stub_catch: \
79 . = 0x4; \
80 text_start = (start) + 0x100; \
81 .section ".text","ax",@progbits; \
82 .balign 0x100; \
83start_text:
84#else
85#define OPEN_TEXT_SECTION(start) \
86 text_start = (start); \
87 .section ".text","ax",@progbits; \
88 . = 0x0; \
89start_text:
90#endif
91
92#define ZERO_FIXED_SECTION(sname, start, end) \
93 sname##_start = (start); \
94 sname##_end = (end); \
95 sname##_len = (end) - (start); \
96 define_data_ftsec sname; \
97 . = 0x0; \
98 . = sname##_len;
99
100#define USE_FIXED_SECTION(sname) \
101 fs_label = start_##sname; \
102 fs_start = sname##_start; \
103 use_ftsec sname;
104
105#define USE_TEXT_SECTION() \
106 fs_label = start_text; \
107 fs_start = text_start; \
108 .text
109
110#define CLOSE_FIXED_SECTION(sname) \
111 USE_FIXED_SECTION(sname); \
112 . = sname##_len; \
113end_##sname:
114
115
116#define __FIXED_SECTION_ENTRY_BEGIN(sname, name, __align) \
117 USE_FIXED_SECTION(sname); \
118 .balign __align; \
119 .global name; \
120name:
121
122#define FIXED_SECTION_ENTRY_BEGIN(sname, name) \
123 __FIXED_SECTION_ENTRY_BEGIN(sname, name, IFETCH_ALIGN_BYTES)
124
125#define FIXED_SECTION_ENTRY_BEGIN_LOCATION(sname, name, start, size) \
126 USE_FIXED_SECTION(sname); \
127 name##_start = (start); \
128 .if ((start) % (size) != 0); \
129 .error "Fixed section exception vector misalignment"; \
130 .endif; \
131 .if ((size) != 0x20) && ((size) != 0x80) && ((size) != 0x100); \
132 .error "Fixed section exception vector bad size"; \
133 .endif; \
134 .if (start) < sname##_start; \
135 .error "Fixed section underflow"; \
136 .abort; \
137 .endif; \
138 . = (start) - sname##_start; \
139 .global name; \
140name:
141
142#define FIXED_SECTION_ENTRY_END_LOCATION(sname, name, start, size) \
143 .if (start) + (size) > sname##_end; \
144 .error "Fixed section overflow"; \
145 .abort; \
146 .endif; \
147 .if (. - name > (start) + (size) - name##_start); \
148 .error "Fixed entry overflow"; \
149 .abort; \
150 .endif; \
151 . = ((start) + (size) - sname##_start); \
152
153
154/*
155 * These macros are used to change symbols in other fixed sections to be
156 * absolute or related to our current fixed section.
157 *
158 * - DEFINE_FIXED_SYMBOL / FIXED_SYMBOL_ABS_ADDR is used to find the
159 * absolute address of a symbol within a fixed section, from any section.
160 *
161 * - ABS_ADDR is used to find the absolute address of any symbol, from within
162 * a fixed section.
163 */
164#define DEFINE_FIXED_SYMBOL(label) \
165 label##_absolute = (label - fs_label + fs_start)
166
167#define FIXED_SYMBOL_ABS_ADDR(label) \
168 (label##_absolute)
169
170#define ABS_ADDR(label) (label - fs_label + fs_start)
171
172#endif /* __ASSEMBLY__ */
173
174#endif /* _ASM_POWERPC_HEAD_64_H */