1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_POWERPC_HEAD_64_H
3 #define _ASM_POWERPC_HEAD_64_H
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.
12 .macro define_ftsec name
13 .section ".head.text.\name\()","ax",@progbits
15 .macro define_data_ftsec name
16 .section ".head.data.\name\()","a",@progbits
19 .section ".head.text.\name\()","ax",@progbits
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.
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
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.
35 * OPEN_FIXED_SECTION(section_name, start_address, end_address)
36 * FIXED_SECTION_ENTRY_BEGIN(section_name, label1)
38 * USE_FIXED_SECTION(section_name)
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)
47 * ZERO_FIXED_SECTION can be used to emit zeroed data.
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
56 * - If the kernel crashes or hangs in very early boot, it could be linker
57 * stubs at the start of the main text.
60 #define OPEN_FIXED_SECTION(sname, start, end) \
61 sname##_start = (start); \
62 sname##_end = (end); \
63 sname##_len = (end) - (start); \
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.
75 #ifdef CONFIG_LD_HEAD_STUB_CATCH
76 #define OPEN_TEXT_SECTION(start) \
77 .section ".linker_stub_catch","ax",@progbits; \
80 text_start = (start) + 0x100; \
81 .section ".text","ax",@progbits; \
85 #define OPEN_TEXT_SECTION(start) \
86 text_start = (start); \
87 .section ".text","ax",@progbits; \
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; \
100 #define USE_FIXED_SECTION(sname) \
103 #define USE_TEXT_SECTION() \
106 #define CLOSE_FIXED_SECTION(sname) \
107 USE_FIXED_SECTION(sname); \
112 #define __FIXED_SECTION_ENTRY_BEGIN(sname, name, __align) \
113 USE_FIXED_SECTION(sname); \
118 #define FIXED_SECTION_ENTRY_BEGIN(sname, name) \
119 __FIXED_SECTION_ENTRY_BEGIN(sname, name, IFETCH_ALIGN_BYTES)
121 #define FIXED_SECTION_ENTRY_BEGIN_LOCATION(sname, name, start, size) \
122 USE_FIXED_SECTION(sname); \
123 name##_start = (start); \
124 .if ((start) % (size) != 0); \
125 .error "Fixed section exception vector misalignment"; \
127 .if ((size) != 0x20) && ((size) != 0x80) && ((size) != 0x100) && ((size) != 0x1000); \
128 .error "Fixed section exception vector bad size"; \
130 .if (start) < sname##_start; \
131 .error "Fixed section underflow"; \
134 . = (start) - sname##_start; \
138 #define FIXED_SECTION_ENTRY_END_LOCATION(sname, name, start, size) \
139 .if (start) + (size) > sname##_end; \
140 .error "Fixed section overflow"; \
143 .if (. - name > (start) + (size) - name##_start); \
144 .error "Fixed entry overflow"; \
147 . = ((start) + (size) - sname##_start); \
151 * These macros are used to change symbols in other fixed sections to be
152 * absolute or related to our current fixed section.
154 * - DEFINE_FIXED_SYMBOL / FIXED_SYMBOL_ABS_ADDR is used to find the
155 * absolute address of a symbol within a fixed section, from any section.
157 * - ABS_ADDR is used to find the absolute address of any symbol, from within
160 // define label as being _in_ sname
161 #define DEFINE_FIXED_SYMBOL(label, sname) \
162 label##_absolute = (label - start_ ## sname + sname ## _start)
164 #define FIXED_SYMBOL_ABS_ADDR(label) \
167 // find label from _within_ sname
168 #define ABS_ADDR(label, sname) (label - start_ ## sname + sname ## _start)
170 #endif /* __ASSEMBLY__ */
172 #endif /* _ASM_POWERPC_HEAD_64_H */