1 /* $NetBSD: cdefs_elf.h,v 1.43 2013/02/07 18:53:34 gdt 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 #if defined(__minix) && !defined(__weak_alias) /* For bitcode support */ 60 #define __weak_alias(alias,sym) \ 61 __asm(".weak " _C_LABEL_STRING(#alias) "\n" \ 62 _C_LABEL_STRING(#alias) " = " _C_LABEL_STRING(#sym)); 63 #endif 64 65 /* Do not use __weak_extern, use __weak_reference instead */ 66 #define __weak_extern(sym) \ 67 __asm(".weak " _C_LABEL_STRING(#sym)); 68 69 #if __GNUC_PREREQ__(4, 0) 70 #define __weak_reference(sym) __attribute__((__weakref__(#sym))) 71 #else 72 #define __weak_reference(sym) ; __asm(".weak " _C_LABEL_STRING(#sym)) 73 #endif 74 75 #if __GNUC_PREREQ__(4, 2) 76 #define __weakref_visible static 77 #else 78 #define __weakref_visible extern 79 #endif 80 81 #define __warn_references(sym,msg) \ 82 __asm(".pushsection .gnu.warning." #sym "\n" \ 83 ".ascii \"" msg "\"\n" \ 84 ".popsection"); 85 86 #else /* !__STDC__ */ 87 88 #ifdef __LEADING_UNDERSCORE 89 #define __weak_alias(alias,sym) ___weak_alias(_/**/alias,_/**/sym) 90 #define ___weak_alias(alias,sym) \ 91 __asm(".weak alias\nalias = sym"); 92 #else 93 #define __weak_alias(alias,sym) \ 94 __asm(".weak alias\nalias = sym"); 95 #endif 96 #ifdef __LEADING_UNDERSCORE 97 #define __weak_extern(sym) ___weak_extern(_/**/sym) 98 #define ___weak_extern(sym) \ 99 __asm(".weak sym"); 100 #else 101 #define __weak_extern(sym) \ 102 __asm(".weak sym"); 103 #endif 104 #define __warn_references(sym,msg) \ 105 __asm(".pushsection .gnu.warning.sym\n" \ 106 ".ascii \"" msg "\"\n" \ 107 ".popsection"); 108 109 #endif /* !__STDC__ */ 110 111 #if __STDC__ 112 #define __SECTIONSTRING(_sec, _str) \ 113 __asm(".pushsection " #_sec "\n" \ 114 ".asciz \"" _str "\"\n" \ 115 ".popsection") 116 #else 117 #define __SECTIONSTRING(_sec, _str) \ 118 __asm(".pushsection _sec\n" \ 119 ".asciz \"" _str "\"\n" \ 120 ".popsection") 121 #endif 122 123 #define __IDSTRING(_n,_s) __SECTIONSTRING(.ident,_s) 124 125 #define __RCSID(_s) __IDSTRING(rcsid,_s) 126 #define __SCCSID(_s) 127 #define __SCCSID2(_s) 128 #define __COPYRIGHT(_s) __SECTIONSTRING(.copyright,_s) 129 130 #define __KERNEL_RCSID(_n, _s) __RCSID(_s) 131 #define __KERNEL_SCCSID(_n, _s) 132 #define __KERNEL_COPYRIGHT(_n, _s) __COPYRIGHT(_s) 133 134 #ifndef __lint__ 135 #define __link_set_make_entry(set, sym) \ 136 static void const * const __link_set_##set##_sym_##sym \ 137 __section("link_set_" #set) __used = (const void *)&sym 138 #define __link_set_make_entry2(set, sym, n) \ 139 static void const * const __link_set_##set##_sym_##sym##_##n \ 140 __section("link_set_" #set) __used = (const void *)&sym[n] 141 #else 142 #define __link_set_make_entry(set, sym) \ 143 extern void const * const __link_set_##set##_sym_##sym 144 #define __link_set_make_entry2(set, sym, n) \ 145 extern void const * const __link_set_##set##_sym_##sym##_##n 146 #endif /* __lint__ */ 147 148 #define __link_set_add_text(set, sym) __link_set_make_entry(set, sym) 149 #define __link_set_add_rodata(set, sym) __link_set_make_entry(set, sym) 150 #define __link_set_add_data(set, sym) __link_set_make_entry(set, sym) 151 #define __link_set_add_bss(set, sym) __link_set_make_entry(set, sym) 152 #define __link_set_add_text2(set, sym, n) __link_set_make_entry2(set, sym, n) 153 #define __link_set_add_rodata2(set, sym, n) __link_set_make_entry2(set, sym, n) 154 #define __link_set_add_data2(set, sym, n) __link_set_make_entry2(set, sym, n) 155 #define __link_set_add_bss2(set, sym, n) __link_set_make_entry2(set, sym, n) 156 157 #define __link_set_decl(set, ptype) \ 158 extern ptype * const __start_link_set_##set[] __dso_hidden; \ 159 extern ptype * const __stop_link_set_##set[] __dso_hidden 160 161 #define __link_set_start(set) (__start_link_set_##set) 162 #define __link_set_end(set) (__stop_link_set_##set) 163 164 #define __link_set_count(set) \ 165 (__link_set_end(set) - __link_set_start(set)) 166 167 168 #ifdef _KERNEL 169 170 /* 171 * On multiprocessor systems we can gain an improvement in performance 172 * by being mindful of which cachelines data is placed in. 173 * 174 * __read_mostly: 175 * 176 * It makes sense to ensure that rarely modified data is not 177 * placed in the same cacheline as frequently modified data. 178 * To mitigate the phenomenon known as "false-sharing" we 179 * can annotate rarely modified variables with __read_mostly. 180 * All such variables are placed into the .data.read_mostly 181 * section in the kernel ELF. 182 * 183 * Prime candidates for __read_mostly annotation are variables 184 * which are hardly ever modified and which are used in code 185 * hot-paths, e.g. pmap_initialized. 186 * 187 * __cacheline_aligned: 188 * 189 * Some data structures (mainly locks) benefit from being aligned 190 * on a cacheline boundary, and having a cacheline to themselves. 191 * This way, the modification of other data items cannot adversely 192 * affect the lock and vice versa. 193 * 194 * Any variables annotated with __cacheline_aligned will be 195 * placed into the .data.cacheline_aligned ELF section. 196 */ 197 #define __read_mostly \ 198 __attribute__((__section__(".data.read_mostly"))) 199 200 #define __cacheline_aligned \ 201 __attribute__((__aligned__(COHERENCY_UNIT), \ 202 __section__(".data.cacheline_aligned"))) 203 204 #endif /* _KERNEL */ 205 206 #endif /* !_SYS_CDEFS_ELF_H_ */ 207