xref: /dragonfly/contrib/binutils-2.27/include/elf/reloc-macros.h (revision e656dc90e3d65d744d534af2f5ea88cf8101ebcf)
1 /* Generic relocation support for BFD.
2    Copyright (C) 1998-2016 Free Software Foundation, Inc.
3 
4    This file is part of BFD, the Binary File Descriptor library.
5 
6    This program is free software; you can redistribute it and/or modify
7    it under the terms of the GNU General Public License as published by
8    the Free Software Foundation; either version 3 of the License, or
9    (at your option) any later version.
10 
11    This program is distributed in the hope that it will be useful,
12    but WITHOUT ANY WARRANTY; without even the implied warranty of
13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14    GNU General Public License for more details.
15 
16    You should have received a copy of the GNU General Public License
17    along with this program; if not, write to the Free Software Foundation,
18    Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
19 
20 /* These macros are used by the various *.h target specific header
21    files to either generate an enum containing all the known relocations
22    for that target, or if RELOC_MACROS_GEN_FUNC is defined, a recognition
23    function is generated instead.  (This is used by binutils/readelf.c)
24 
25    Given a header file like this:
26 
27           START_RELOC_NUMBERS (foo)
28               RELOC_NUMBER (R_foo_NONE,    0)
29               RELOC_NUMBER (R_foo_32,      1)
30               EMPTY_RELOC  (R_foo_good)
31               FAKE_RELOC   (R_foo_illegal, 9)
32           END_RELOC_NUMBERS (R_foo_count)
33 
34    Then the following will be produced by default (ie if
35    RELOC_MACROS_GEN_FUNC is *not* defined).
36 
37           enum foo
38           {
39             R_foo_NONE = 0,
40             R_foo_32 = 1,
41             R_foo_good,
42             R_foo_illegal = 9,
43             R_foo_count
44           };
45 
46    Note: The value of the symbol defined in the END_RELOC_NUMBERS
47    macro (R_foo_count in the case of the example above) will be
48    set to the value of the whichever *_RELOC macro precedes it plus
49    one.  Therefore if you intend to use the symbol as a sentinel for
50    the highest valid macro value you should make sure that the
51    preceding *_RELOC macro is the highest valid number.  ie a
52    declaration like this:
53 
54           START_RELOC_NUMBERS (foo)
55               RELOC_NUMBER (R_foo_NONE,    0)
56               RELOC_NUMBER (R_foo_32,      1)
57               FAKE_RELOC   (R_foo_illegal, 9)
58               FAKE_RELOC   (R_foo_synonym, 0)
59           END_RELOC_NUMBERS (R_foo_count)
60 
61    will result in R_foo_count having a value of 1 (R_foo_synonym + 1)
62    rather than 10 or 2 as might be expected.
63 
64    Alternatively you can assign a value to END_RELOC_NUMBERS symbol
65    explicitly, like this:
66 
67           START_RELOC_NUMBERS (foo)
68               RELOC_NUMBER (R_foo_NONE,    0)
69               RELOC_NUMBER (R_foo_32,      1)
70               FAKE_RELOC   (R_foo_illegal, 9)
71               FAKE_RELOC   (R_foo_synonym, 0)
72           END_RELOC_NUMBERS (R_foo_count = 2)
73 
74    If RELOC_MACROS_GEN_FUNC *is* defined, then instead the
75    following function will be generated:
76 
77           static const char *foo (unsigned long rtype);
78           static const char *
79           foo (unsigned long rtype)
80           {
81              switch (rtype)
82              {
83              case 0: return "R_foo_NONE";
84              case 1: return "R_foo_32";
85              default: return NULL;
86              }
87           }
88    */
89 
90 #ifndef _RELOC_MACROS_H
91 #define _RELOC_MACROS_H
92 
93 #ifdef RELOC_MACROS_GEN_FUNC
94 
95 /* This function takes the relocation number and returns the
96    string version name of the name of that relocation.  If
97    the relocation is not recognised, NULL is returned.  */
98 
99 #define START_RELOC_NUMBERS(name)                                     \
100 static const char *name (unsigned long rtype);                        \
101 static const char *                                                   \
102 name (unsigned long rtype)                                            \
103 {                                                                               \
104   switch (rtype)                                                      \
105     {
106 
107 #define RELOC_NUMBER(name, number) \
108     case number: return #name;
109 
110 #define FAKE_RELOC(name, number)
111 #define EMPTY_RELOC(name)
112 
113 #define END_RELOC_NUMBERS(name)         \
114     default: return NULL;     \
115     }                                   \
116 }
117 
118 
119 #else /* Default to generating enum.  */
120 
121 #define START_RELOC_NUMBERS(name)   enum name {
122 #define RELOC_NUMBER(name, number)  name = number,
123 #define FAKE_RELOC(name, number)    name = number,
124 #define EMPTY_RELOC(name)           name,
125 #define END_RELOC_NUMBERS(name)     name };
126 
127 #endif
128 
129 #endif /* _RELOC_MACROS_H */
130