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