| 1 | /* $NetBSD: cdefs_elf.h,v 1.52 2016/06/07 12:09:29 joerg Exp $ */ |
| 2 | |
| 3 | /* |
| 4 | * Copyright (c) 1995, 1996 Carnegie-Mellon University. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * Author: Chris G. Demetriou |
| 8 | * |
| 9 | * Permission to use, copy, modify and distribute this software and |
| 10 | * its documentation is hereby granted, provided that both the copyright |
| 11 | * notice and this permission notice appear in all copies of the |
| 12 | * software, derivative works or modified versions, and any portions |
| 13 | * thereof, and that both notices appear in supporting documentation. |
| 14 | * |
| 15 | * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" |
| 16 | * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND |
| 17 | * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. |
| 18 | * |
| 19 | * Carnegie Mellon requests users of this software to return to |
| 20 | * |
| 21 | * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU |
| 22 | * School of Computer Science |
| 23 | * Carnegie Mellon University |
| 24 | * Pittsburgh PA 15213-3890 |
| 25 | * |
| 26 | * any improvements or extensions that they make and grant Carnegie the |
| 27 | * rights to redistribute these changes. |
| 28 | */ |
| 29 | |
| 30 | #ifndef _SYS_CDEFS_ELF_H_ |
| 31 | #define _SYS_CDEFS_ELF_H_ |
| 32 | |
| 33 | #ifdef __LEADING_UNDERSCORE |
| 34 | #define _C_LABEL(x) __CONCAT(_,x) |
| 35 | #define _C_LABEL_STRING(x) "_"x |
| 36 | #else |
| 37 | #define _C_LABEL(x) x |
| 38 | #define _C_LABEL_STRING(x) x |
| 39 | #endif |
| 40 | |
| 41 | #if __STDC__ |
| 42 | #define ___RENAME(x) __asm(___STRING(_C_LABEL(x))) |
| 43 | #else |
| 44 | #ifdef __LEADING_UNDERSCORE |
| 45 | #define ___RENAME(x) ____RENAME(_/**/x) |
| 46 | #define ____RENAME(x) __asm(___STRING(x)) |
| 47 | #else |
| 48 | #define ___RENAME(x) __asm(___STRING(x)) |
| 49 | #endif |
| 50 | #endif |
| 51 | |
| 52 | #define __indr_reference(sym,alias) /* nada, since we do weak refs */ |
| 53 | |
| 54 | #if __STDC__ |
| 55 | #define __strong_alias(alias,sym) \ |
| 56 | __asm(".global " _C_LABEL_STRING(#alias) "\n" \ |
| 57 | _C_LABEL_STRING(#alias) " = " _C_LABEL_STRING(#sym)); |
| 58 | |
| 59 | #define __weak_alias(alias,sym) \ |
| 60 | __asm(".weak " _C_LABEL_STRING(#alias) "\n" \ |
| 61 | _C_LABEL_STRING(#alias) " = " _C_LABEL_STRING(#sym)); |
| 62 | |
| 63 | /* Do not use __weak_extern, use __weak_reference instead */ |
| 64 | #define __weak_extern(sym) \ |
| 65 | __asm(".weak " _C_LABEL_STRING(#sym)); |
| 66 | |
| 67 | #if __GNUC_PREREQ__(4, 0) |
| 68 | #define __weak __attribute__((__weak__)) |
| 69 | #else |
| 70 | #define __weak |
| 71 | #endif |
| 72 | |
| 73 | #if __GNUC_PREREQ__(4, 0) |
| 74 | #define __weak_reference(sym) __attribute__((__weakref__(#sym))) |
| 75 | #else |
| 76 | #define __weak_reference(sym) ; __asm(".weak " _C_LABEL_STRING(#sym)) |
| 77 | #endif |
| 78 | |
| 79 | #if __GNUC_PREREQ__(4, 2) |
| 80 | #define __weakref_visible static |
| 81 | #else |
| 82 | #define __weakref_visible extern |
| 83 | #endif |
| 84 | |
| 85 | #define __warn_references(sym,msg) \ |
| 86 | __asm(".pushsection .gnu.warning." #sym "\n" \ |
| 87 | ".ascii \"" msg "\"\n" \ |
| 88 | ".popsection"); |
| 89 | |
| 90 | #else /* !__STDC__ */ |
| 91 | |
| 92 | #ifdef __LEADING_UNDERSCORE |
| 93 | #define __weak_alias(alias,sym) ___weak_alias(_/**/alias,_/**/sym) |
| 94 | #define ___weak_alias(alias,sym) \ |
| 95 | __asm(".weak alias\nalias = sym"); |
| 96 | #else |
| 97 | #define __weak_alias(alias,sym) \ |
| 98 | __asm(".weak alias\nalias = sym"); |
| 99 | #endif |
| 100 | #ifdef __LEADING_UNDERSCORE |
| 101 | #define __weak_extern(sym) ___weak_extern(_/**/sym) |
| 102 | #define ___weak_extern(sym) \ |
| 103 | __asm(".weak sym"); |
| 104 | #else |
| 105 | #define __weak_extern(sym) \ |
| 106 | __asm(".weak sym"); |
| 107 | #endif |
| 108 | #define __warn_references(sym,msg) \ |
| 109 | __asm(".pushsection .gnu.warning.sym\n" \ |
| 110 | ".ascii \"" msg "\"\n" \ |
| 111 | ".popsection"); |
| 112 | |
| 113 | #endif /* !__STDC__ */ |
| 114 | |
| 115 | #if __arm__ |
| 116 | #define __ifunc(name, resolver) \ |
| 117 | __asm(".globl " _C_LABEL_STRING(#name) "\n" \ |
| 118 | ".type " _C_LABEL_STRING(#name) ", %gnu_indirect_function\n" \ |
| 119 | _C_LABEL_STRING(#name) " = " _C_LABEL_STRING(#resolver)) |
| 120 | #else |
| 121 | #define __ifunc(name, resolver) \ |
| 122 | __asm(".globl " _C_LABEL_STRING(#name) "\n" \ |
| 123 | ".type " _C_LABEL_STRING(#name) ", @gnu_indirect_function\n" \ |
| 124 | _C_LABEL_STRING(#name) " = " _C_LABEL_STRING(#resolver)) |
| 125 | #endif |
| 126 | |
| 127 | #if __STDC__ |
| 128 | #define __SECTIONSTRING(_sec, _str) \ |
| 129 | __asm(".pushsection " #_sec "\n" \ |
| 130 | ".asciz \"" _str "\"\n" \ |
| 131 | ".popsection") |
| 132 | #else |
| 133 | #define __SECTIONSTRING(_sec, _str) \ |
| 134 | __asm(".pushsection _sec\n" \ |
| 135 | ".asciz \"" _str "\"\n" \ |
| 136 | ".popsection") |
| 137 | #endif |
| 138 | |
| 139 | #define __IDSTRING(_n,_s) __SECTIONSTRING(.ident,_s) |
| 140 | |
| 141 | #define __RCSID(_s) __IDSTRING(rcsid,_s) |
| 142 | #define __SCCSID(_s) |
| 143 | #define __SCCSID2(_s) |
| 144 | #define __COPYRIGHT(_s) __SECTIONSTRING(.copyright,_s) |
| 145 | |
| 146 | #define __KERNEL_RCSID(_n, _s) __RCSID(_s) |
| 147 | #define __KERNEL_SCCSID(_n, _s) |
| 148 | #define __KERNEL_COPYRIGHT(_n, _s) __COPYRIGHT(_s) |
| 149 | |
| 150 | #ifndef __lint__ |
| 151 | #define __link_set_make_entry(set, sym) \ |
| 152 | static void const * const __link_set_##set##_sym_##sym \ |
| 153 | __section("link_set_" #set) __used = (const void *)&sym |
| 154 | #define __link_set_make_entry2(set, sym, n) \ |
| 155 | static void const * const __link_set_##set##_sym_##sym##_##n \ |
| 156 | __section("link_set_" #set) __used = (const void *)&sym[n] |
| 157 | #else |
| 158 | #define __link_set_make_entry(set, sym) \ |
| 159 | extern void const * const __link_set_##set##_sym_##sym |
| 160 | #define __link_set_make_entry2(set, sym, n) \ |
| 161 | extern void const * const __link_set_##set##_sym_##sym##_##n |
| 162 | #endif /* __lint__ */ |
| 163 | |
| 164 | #define __link_set_add_text(set, sym) __link_set_make_entry(set, sym) |
| 165 | #define __link_set_add_rodata(set, sym) __link_set_make_entry(set, sym) |
| 166 | #define __link_set_add_data(set, sym) __link_set_make_entry(set, sym) |
| 167 | #define __link_set_add_bss(set, sym) __link_set_make_entry(set, sym) |
| 168 | #define __link_set_add_text2(set, sym, n) __link_set_make_entry2(set, sym, n) |
| 169 | #define __link_set_add_rodata2(set, sym, n) __link_set_make_entry2(set, sym, n) |
| 170 | #define __link_set_add_data2(set, sym, n) __link_set_make_entry2(set, sym, n) |
| 171 | #define __link_set_add_bss2(set, sym, n) __link_set_make_entry2(set, sym, n) |
| 172 | |
| 173 | #define __link_set_start(set) (__start_link_set_##set) |
| 174 | #define __link_set_end(set) (__stop_link_set_##set) |
| 175 | |
| 176 | #define __link_set_decl(set, ptype) \ |
| 177 | extern ptype * const __link_set_start(set)[] __dso_hidden; \ |
| 178 | __asm__(".hidden " __STRING(__stop_link_set_##set)); \ |
| 179 | extern ptype * const __link_set_end(set)[] __weak __dso_hidden |
| 180 | |
| 181 | #define __link_set_count(set) \ |
| 182 | (__link_set_end(set) - __link_set_start(set)) |
| 183 | |
| 184 | |
| 185 | #ifdef _KERNEL |
| 186 | |
| 187 | /* |
| 188 | * On multiprocessor systems we can gain an improvement in performance |
| 189 | * by being mindful of which cachelines data is placed in. |
| 190 | * |
| 191 | * __read_mostly: |
| 192 | * |
| 193 | * It makes sense to ensure that rarely modified data is not |
| 194 | * placed in the same cacheline as frequently modified data. |
| 195 | * To mitigate the phenomenon known as "false-sharing" we |
| 196 | * can annotate rarely modified variables with __read_mostly. |
| 197 | * All such variables are placed into the .data.read_mostly |
| 198 | * section in the kernel ELF. |
| 199 | * |
| 200 | * Prime candidates for __read_mostly annotation are variables |
| 201 | * which are hardly ever modified and which are used in code |
| 202 | * hot-paths, e.g. pmap_initialized. |
| 203 | * |
| 204 | * __cacheline_aligned: |
| 205 | * |
| 206 | * Some data structures (mainly locks) benefit from being aligned |
| 207 | * on a cacheline boundary, and having a cacheline to themselves. |
| 208 | * This way, the modification of other data items cannot adversely |
| 209 | * affect the lock and vice versa. |
| 210 | * |
| 211 | * Any variables annotated with __cacheline_aligned will be |
| 212 | * placed into the .data.cacheline_aligned ELF section. |
| 213 | */ |
| 214 | #define __read_mostly \ |
| 215 | __attribute__((__section__(".data.read_mostly"))) |
| 216 | |
| 217 | #define __cacheline_aligned \ |
| 218 | __attribute__((__aligned__(COHERENCY_UNIT), \ |
| 219 | __section__(".data.cacheline_aligned"))) |
| 220 | |
| 221 | #endif /* _KERNEL */ |
| 222 | |
| 223 | #endif /* !_SYS_CDEFS_ELF_H_ */ |
| 224 | |