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