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82838bd6 CC |
1 | // plugin_section_alignment.cc -- plugins to test ordering with {size,alignment} |
2 | // | |
219d1afa | 3 | // Copyright (C) 2016-2018 Free Software Foundation, Inc. |
82838bd6 CC |
4 | // Written by Than McIntosh <thanm@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 | ||
24 | #ifdef HAVE_CONFIG_H | |
25 | #include "config.h" | |
26 | #endif | |
27 | ||
28 | #include <assert.h> | |
29 | #include <stdio.h> | |
30 | #include <stdlib.h> | |
31 | #include <string.h> | |
32 | ||
33 | #include <string> | |
34 | #include <vector> | |
35 | #include <algorithm> | |
36 | ||
37 | #include "plugin-api.h" | |
38 | ||
39 | static ld_plugin_get_input_section_count get_input_section_count = NULL; | |
40 | static ld_plugin_get_input_section_alignment get_input_section_alignment = NULL; | |
41 | static ld_plugin_get_input_section_size get_input_section_size = NULL; | |
42 | static ld_plugin_get_input_section_name get_input_section_name = NULL; | |
43 | static ld_plugin_update_section_order update_section_order = NULL; | |
44 | static ld_plugin_allow_section_ordering allow_section_ordering = NULL; | |
45 | ||
46 | extern "C" { | |
47 | enum ld_plugin_status onload(struct ld_plugin_tv *tv); | |
48 | enum ld_plugin_status claim_file_hook(const struct ld_plugin_input_file *file, | |
49 | int *claimed); | |
50 | enum ld_plugin_status all_symbols_read_hook(void); | |
51 | } | |
52 | ||
53 | typedef enum { FL_BSS, FL_DATA, FL_RODATA, FL_UNKNOWN } sec_flavor; | |
54 | ||
55 | inline static int is_prefix_of(const char *prefix, const char *str) | |
56 | { | |
57 | return strncmp(prefix, str, strlen(prefix)) == 0; | |
58 | } | |
59 | ||
60 | inline static sec_flavor flavor_from_name(const char *secname) | |
61 | { | |
62 | if (is_prefix_of(".data.v", secname)) { | |
63 | return FL_DATA; | |
64 | } else if (is_prefix_of(".bss.v", secname)) { | |
65 | return FL_BSS; | |
66 | } else if (is_prefix_of(".rodata.v", secname)) { | |
67 | return FL_RODATA; | |
68 | } else { | |
69 | return FL_UNKNOWN; | |
70 | } | |
71 | } | |
72 | ||
73 | struct SectionInfo { | |
74 | ld_plugin_section plugin_section; | |
75 | std::string name; | |
76 | uint64_t size; | |
77 | sec_flavor flavor; | |
78 | unsigned align; | |
79 | ||
80 | static bool SectionInfoLt(const SectionInfo &i1, | |
81 | const SectionInfo &i2) | |
82 | { | |
83 | if (i1.flavor != i2.flavor) { | |
84 | return ((unsigned) i1.flavor) < ((unsigned) i2.flavor); | |
85 | } | |
86 | switch (i1.flavor) { | |
87 | case FL_DATA: | |
88 | // Sort data items by increasing alignment then increasing size | |
89 | if (i1.align != i2.align) { | |
90 | return ((unsigned) i1.align) < ((unsigned) i2.align); | |
91 | } | |
92 | if (i1.size != i2.size) { | |
93 | return ((unsigned) i1.size) < ((unsigned) i2.size); | |
94 | } | |
95 | break; | |
96 | case FL_BSS: | |
97 | // Sort bss items by decreasing alignment then decreasing size | |
98 | if (i1.align != i2.align) { | |
99 | return ((unsigned) i2.align) < ((unsigned) i1.align); | |
100 | } | |
101 | if (i1.size != i2.size) { | |
102 | return ((unsigned) i2.size) < ((unsigned) i1.size); | |
103 | } | |
104 | break; | |
105 | case FL_RODATA: | |
106 | // Sort rodata items by decreasing alignment then increasing size | |
107 | if (i1.align != i2.align) { | |
108 | return ((unsigned) i2.align) < ((unsigned) i1.align); | |
109 | } | |
110 | if (i1.size != i2.size) { | |
111 | return ((unsigned) i1.size) < ((unsigned) i2.size); | |
112 | } | |
113 | default: | |
114 | break; | |
115 | } | |
116 | ||
117 | // Break ties by name | |
118 | return i1.name.compare(i2.name) < 0; | |
119 | } | |
120 | ||
121 | }; | |
122 | typedef std::vector<SectionInfo> section_info_vector; | |
123 | section_info_vector raw_sections; | |
124 | ||
125 | // Set to 1 for debugging output | |
126 | unsigned trace = 0; | |
127 | ||
128 | extern "C" { | |
129 | ||
130 | // Plugin entry point. | |
131 | enum ld_plugin_status onload(struct ld_plugin_tv *tv) | |
132 | { | |
133 | struct ld_plugin_tv *entry; | |
134 | for (entry = tv; entry->tv_tag != LDPT_NULL; ++entry) | |
135 | { | |
136 | switch (entry->tv_tag) | |
137 | { | |
138 | case LDPT_OPTION: | |
139 | if (!strcmp(entry->tv_u.tv_string,"-trace")) { | |
140 | fprintf(stderr, "enabling tracing\n"); | |
141 | trace += 1; | |
142 | } else { | |
143 | fprintf(stderr, "unknown plugin option %s", entry->tv_u.tv_string); | |
144 | } | |
145 | break; | |
146 | case LDPT_REGISTER_CLAIM_FILE_HOOK: | |
147 | assert((*entry->tv_u.tv_register_claim_file)(claim_file_hook) == | |
148 | LDPS_OK); | |
149 | break; | |
150 | case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: | |
151 | assert((*entry->tv_u.tv_register_all_symbols_read)( | |
152 | all_symbols_read_hook) == LDPS_OK); | |
153 | break; | |
154 | case LDPT_GET_INPUT_SECTION_COUNT: | |
155 | get_input_section_count = *entry->tv_u.tv_get_input_section_count; | |
156 | break; | |
157 | case LDPT_GET_INPUT_SECTION_NAME: | |
158 | get_input_section_name = *entry->tv_u.tv_get_input_section_name; | |
159 | break; | |
160 | case LDPT_GET_INPUT_SECTION_ALIGNMENT: | |
161 | get_input_section_alignment = | |
162 | *entry->tv_u.tv_get_input_section_alignment; | |
163 | break; | |
164 | case LDPT_GET_INPUT_SECTION_SIZE: | |
165 | get_input_section_size = *entry->tv_u.tv_get_input_section_size; | |
166 | break; | |
167 | case LDPT_UPDATE_SECTION_ORDER: | |
168 | update_section_order = *entry->tv_u.tv_update_section_order; | |
169 | break; | |
170 | case LDPT_ALLOW_SECTION_ORDERING: | |
171 | allow_section_ordering = *entry->tv_u.tv_allow_section_ordering; | |
172 | break; | |
173 | default: | |
174 | break; | |
175 | } | |
176 | } | |
177 | ||
178 | if (get_input_section_count == NULL || get_input_section_alignment == NULL || | |
179 | get_input_section_size == NULL || get_input_section_name == NULL || | |
180 | update_section_order == NULL || allow_section_ordering == NULL) { | |
181 | fprintf(stderr, "Some interfaces are missing\n"); | |
182 | return LDPS_ERR; | |
183 | } | |
184 | ||
185 | return LDPS_OK; | |
186 | } | |
187 | ||
188 | // This function is called by the linker for every new object it encounters. | |
189 | enum ld_plugin_status claim_file_hook(const struct ld_plugin_input_file *file, | |
190 | int *claimed) | |
191 | { | |
192 | static bool is_ordering_specified = false; | |
193 | struct ld_plugin_section section; | |
194 | unsigned count = 0; | |
195 | unsigned shndx; | |
196 | ||
197 | *claimed = 0; | |
198 | if (!is_ordering_specified) { | |
199 | // Inform the linker to prepare for section reordering. | |
200 | (*allow_section_ordering)(); | |
201 | is_ordering_specified = true; | |
202 | } | |
203 | ||
204 | (*get_input_section_count)(file->handle, &count); | |
205 | ||
206 | for (shndx = 0; shndx < count; ++shndx) { | |
207 | char *name = NULL; | |
208 | ||
209 | section.handle = file->handle; | |
210 | section.shndx = shndx; | |
211 | (*get_input_section_name)(section, &name); | |
212 | if (is_prefix_of(".data.v", name) || | |
213 | is_prefix_of(".bss.v", name) || | |
214 | is_prefix_of(".rodata.v", name)) { | |
215 | SectionInfo si; | |
216 | si.plugin_section.handle = file->handle; | |
217 | si.plugin_section.shndx = shndx; | |
218 | (*get_input_section_size)(section, &si.size); | |
219 | (*get_input_section_alignment)(section, &si.align); | |
220 | si.name = name; | |
221 | si.flavor = flavor_from_name(name); | |
222 | raw_sections.push_back(si); | |
223 | } | |
224 | } | |
225 | ||
226 | return LDPS_OK; | |
227 | } | |
228 | ||
229 | // This function is called by the linker after all the symbols have been read. | |
230 | // At this stage, it is fine to tell the linker the desired function order. | |
231 | ||
232 | enum ld_plugin_status all_symbols_read_hook(void) | |
233 | { | |
234 | // We expect to see a total of twelve sections -- if this is not the case | |
235 | // then something went wrong somewhere along the way. | |
236 | if (raw_sections.size() != 12) { | |
237 | fprintf(stderr, "Expected 12 sections, found %u sections", | |
238 | (unsigned) raw_sections.size()); | |
239 | return LDPS_ERR; | |
240 | } | |
241 | ||
242 | std::sort(raw_sections.begin(), raw_sections.end(), | |
243 | SectionInfo::SectionInfoLt); | |
244 | ||
245 | struct ld_plugin_section section_list[12]; | |
246 | for (unsigned ii = 0; ii < 12; ++ii) { | |
247 | section_list[ii] = raw_sections[ii].plugin_section; | |
248 | } | |
249 | ||
250 | if (trace) { | |
251 | fprintf(stderr, "Specified section order is:\n"); | |
252 | for (section_info_vector::iterator it = raw_sections.begin(); | |
253 | it != raw_sections.end(); | |
254 | ++it) { | |
255 | const SectionInfo &si = (*it); | |
256 | fprintf(stderr, "Idx=%u Name=%s Align=%u Size=%u\n", | |
257 | si.plugin_section.shndx, si.name.c_str(), si.align, | |
258 | (unsigned) si.size); | |
259 | } | |
260 | } | |
261 | ||
262 | update_section_order(section_list, 12); | |
263 | ||
264 | return LDPS_OK; | |
265 | } | |
266 | ||
267 | } // end extern "C" |