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f0558624 ST |
1 | /* plugin_section_reorder.c -- Simple plugin to reorder function sections |
2 | ||
82704155 | 3 | Copyright (C) 2011-2019 Free Software Foundation, Inc. |
f0558624 ST |
4 | Written by Sriraman Tallam <tmsriram@google.com>. |
5 | ||
6 | This file is part of gold. | |
7 | ||
8 | This program is free software; you can redistribute it and/or modify | |
9 | it under the terms of the GNU General Public License as published by | |
10 | the Free Software Foundation; either version 3 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | This program is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | GNU General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with this program; if not, write to the Free Software | |
20 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, | |
21 | MA 02110-1301, USA. */ | |
22 | ||
23 | #ifdef HAVE_CONFIG_H | |
24 | #include "config.h" | |
25 | #endif | |
26 | ||
27 | #include <stdio.h> | |
28 | #include <stdlib.h> | |
29 | #include <string.h> | |
30 | #include <assert.h> | |
31 | #include "plugin-api.h" | |
32 | ||
33 | static ld_plugin_get_input_section_count get_input_section_count = NULL; | |
34 | static ld_plugin_get_input_section_type get_input_section_type = NULL; | |
35 | static ld_plugin_get_input_section_name get_input_section_name = NULL; | |
36 | static ld_plugin_get_input_section_contents get_input_section_contents = NULL; | |
37 | static ld_plugin_update_section_order update_section_order = NULL; | |
38 | static ld_plugin_allow_section_ordering allow_section_ordering = NULL; | |
16164a6b ST |
39 | static ld_plugin_allow_unique_segment_for_sections |
40 | allow_unique_segment_for_sections = NULL; | |
41 | static ld_plugin_unique_segment_for_sections unique_segment_for_sections = NULL; | |
f0558624 ST |
42 | |
43 | enum ld_plugin_status onload(struct ld_plugin_tv *tv); | |
44 | enum ld_plugin_status claim_file_hook(const struct ld_plugin_input_file *file, | |
45 | int *claimed); | |
46 | enum ld_plugin_status all_symbols_read_hook(void); | |
47 | ||
48 | /* Plugin entry point. */ | |
49 | enum ld_plugin_status | |
50 | onload(struct ld_plugin_tv *tv) | |
51 | { | |
52 | struct ld_plugin_tv *entry; | |
53 | for (entry = tv; entry->tv_tag != LDPT_NULL; ++entry) | |
54 | { | |
55 | switch (entry->tv_tag) | |
56 | { | |
57 | case LDPT_REGISTER_CLAIM_FILE_HOOK: | |
16164a6b ST |
58 | assert((*entry->tv_u.tv_register_claim_file) (claim_file_hook) |
59 | == LDPS_OK); | |
f0558624 ST |
60 | break; |
61 | case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: | |
16164a6b ST |
62 | assert((*entry->tv_u.tv_register_all_symbols_read) |
63 | (all_symbols_read_hook) | |
64 | == LDPS_OK); | |
f0558624 ST |
65 | break; |
66 | case LDPT_GET_INPUT_SECTION_COUNT: | |
67 | get_input_section_count = *entry->tv_u.tv_get_input_section_count; | |
68 | break; | |
69 | case LDPT_GET_INPUT_SECTION_TYPE: | |
70 | get_input_section_type = *entry->tv_u.tv_get_input_section_type; | |
71 | break; | |
72 | case LDPT_GET_INPUT_SECTION_NAME: | |
73 | get_input_section_name = *entry->tv_u.tv_get_input_section_name; | |
74 | break; | |
75 | case LDPT_GET_INPUT_SECTION_CONTENTS: | |
16164a6b ST |
76 | get_input_section_contents |
77 | = *entry->tv_u.tv_get_input_section_contents; | |
f0558624 ST |
78 | break; |
79 | case LDPT_UPDATE_SECTION_ORDER: | |
80 | update_section_order = *entry->tv_u.tv_update_section_order; | |
81 | break; | |
82 | case LDPT_ALLOW_SECTION_ORDERING: | |
83 | allow_section_ordering = *entry->tv_u.tv_allow_section_ordering; | |
84 | break; | |
16164a6b ST |
85 | case LDPT_ALLOW_UNIQUE_SEGMENT_FOR_SECTIONS: |
86 | allow_unique_segment_for_sections | |
87 | = *entry->tv_u.tv_allow_unique_segment_for_sections; | |
a61d92b7 | 88 | break; |
16164a6b ST |
89 | case LDPT_UNIQUE_SEGMENT_FOR_SECTIONS: |
90 | unique_segment_for_sections | |
91 | = *entry->tv_u.tv_unique_segment_for_sections; | |
92 | break; | |
f0558624 ST |
93 | default: |
94 | break; | |
95 | } | |
96 | } | |
97 | ||
98 | if (get_input_section_count == NULL | |
99 | || get_input_section_type == NULL | |
100 | || get_input_section_name == NULL | |
101 | || get_input_section_contents == NULL | |
102 | || update_section_order == NULL | |
16164a6b ST |
103 | || allow_section_ordering == NULL |
104 | || allow_unique_segment_for_sections == NULL | |
105 | || unique_segment_for_sections == NULL) | |
f0558624 ST |
106 | { |
107 | fprintf(stderr, "Some interfaces are missing\n"); | |
108 | return LDPS_ERR; | |
109 | } | |
110 | ||
111 | return LDPS_OK; | |
112 | } | |
113 | ||
114 | inline static int is_prefix_of(const char *prefix, const char *str) | |
115 | { | |
116 | return strncmp(prefix, str, strlen (prefix)) == 0; | |
117 | } | |
118 | ||
119 | struct ld_plugin_section section_list[3]; | |
120 | int num_entries = 0; | |
121 | ||
122 | /* This function is called by the linker for every new object it encounters. */ | |
123 | enum ld_plugin_status | |
124 | claim_file_hook(const struct ld_plugin_input_file *file, int *claimed) | |
125 | { | |
126 | static int is_ordering_specified = 0; | |
127 | struct ld_plugin_section section; | |
128 | unsigned int count = 0; | |
129 | unsigned int shndx; | |
130 | ||
131 | *claimed = 0; | |
132 | if (is_ordering_specified == 0) | |
133 | { | |
134 | /* Inform the linker to prepare for section reordering. */ | |
135 | (*allow_section_ordering)(); | |
16164a6b ST |
136 | /* Inform the linker to prepare to map some sections to unique |
137 | segments. */ | |
138 | (*allow_unique_segment_for_sections)(); | |
f0558624 ST |
139 | is_ordering_specified = 1; |
140 | } | |
141 | ||
142 | (*get_input_section_count)(file->handle, &count); | |
143 | ||
144 | for (shndx = 0; shndx < count; ++shndx) | |
145 | { | |
146 | char *name = NULL; | |
147 | int position = 3; | |
148 | ||
149 | section.handle = file->handle; | |
150 | section.shndx = shndx; | |
151 | (*get_input_section_name)(section, &name); | |
152 | ||
153 | /* Order is foo() followed by bar() followed by baz() */ | |
154 | if (is_prefix_of(".text.", name)) | |
155 | { | |
156 | if (strstr(name, "_Z3foov") != NULL) | |
157 | position = 0; | |
158 | else if (strstr(name, "_Z3barv") != NULL) | |
159 | position = 1; | |
160 | else if (strstr(name, "_Z3bazv") != NULL) | |
161 | position = 2; | |
162 | else | |
163 | position = 3; | |
164 | } | |
165 | if (position < 3) | |
166 | { | |
167 | section_list[position].handle = file->handle; | |
168 | section_list[position].shndx = shndx; | |
169 | num_entries++; | |
170 | } | |
171 | } | |
172 | return LDPS_OK; | |
173 | } | |
174 | ||
175 | /* This function is called by the linker after all the symbols have been read. | |
176 | At this stage, it is fine to tell the linker the desired function order. */ | |
177 | ||
178 | enum ld_plugin_status | |
179 | all_symbols_read_hook(void) | |
180 | { | |
181 | if (num_entries == 3) | |
16164a6b ST |
182 | { |
183 | update_section_order(section_list, num_entries); | |
184 | unique_segment_for_sections (".text.plugin_created_unique", 0, 0x1000, | |
185 | section_list, num_entries); | |
186 | } | |
f0558624 ST |
187 | |
188 | return LDPS_OK; | |
189 | } |