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\()","ax",@progbits 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; \ 66 start_##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; \ 78 linker_stub_catch: \ 79 . = 0x4; \ 80 text_start = (start) + 0x100; \ 81 .section ".text","ax",@progbits; \ 82 .balign 0x100; \ 83 start_text: 84 #else 85 #define OPEN_TEXT_SECTION(start) \ 86 text_start = (start); \ 87 .section ".text","ax",@progbits; \ 88 . = 0x0; \ 89 start_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 use_ftsec sname; 102 103 #define USE_TEXT_SECTION() \ 104 .text 105 106 #define CLOSE_FIXED_SECTION(sname) \ 107 USE_FIXED_SECTION(sname); \ 108 . = sname##_len; \ 109 end_##sname: 110 111 112 #define __FIXED_SECTION_ENTRY_BEGIN(sname, name, __align) \ 113 USE_FIXED_SECTION(sname); \ 114 .balign __align; \ 115 .global name; \ 116 name: 117 118 #define FIXED_SECTION_ENTRY_BEGIN(sname, name) \ 119 __FIXED_SECTION_ENTRY_BEGIN(sname, name, IFETCH_ALIGN_BYTES) 120 121 #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"; \ 126 .endif; \ 127 .if ((size) != 0x20) && ((size) != 0x80) && ((size) != 0x100) && ((size) != 0x1000); \ 128 .error "Fixed section exception vector bad size"; \ 129 .endif; \ 130 .if (start) < sname##_start; \ 131 .error "Fixed section underflow"; \ 132 .abort; \ 133 .endif; \ 134 . = (start) - sname##_start; \ 135 .global name; \ 136 name: 137 138 #define FIXED_SECTION_ENTRY_END_LOCATION(sname, name, start, size) \ 139 .if (start) + (size) > sname##_end; \ 140 .error "Fixed section overflow"; \ 141 .abort; \ 142 .endif; \ 143 .if (. - name > (start) + (size) - name##_start); \ 144 .error "Fixed entry overflow"; \ 145 .abort; \ 146 .endif; \ 147 . = ((start) + (size) - sname##_start); \ 148 149 150 /* 151 * These macros are used to change symbols in other fixed sections to be 152 * absolute or related to our current fixed section. 153 * 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. 156 * 157 * - ABS_ADDR is used to find the absolute address of any symbol, from within 158 * a fixed section. 159 */ 160 // define label as being _in_ sname 161 #define DEFINE_FIXED_SYMBOL(label, sname) \ 162 label##_absolute = (label - start_ ## sname + sname ## _start) 163 164 #define FIXED_SYMBOL_ABS_ADDR(label) \ 165 (label##_absolute) 166 167 // find label from _within_ sname 168 #define ABS_ADDR(label, sname) (label - start_ ## sname + sname ## _start) 169 170 #endif /* __ASSEMBLY__ */ 171 172 #endif /* _ASM_POWERPC_HEAD_64_H */ 173