Mercurial > hg > truffle
comparison agent/src/os/linux/symtab.c @ 1294:7de45b5044c3
6932270: Allow Java's ELF symtab reader to use separate debuginfo files
Reviewed-by: never
Contributed-by: Andrew Haley <aph@redhat.com>
author | never |
---|---|
date | Tue, 09 Mar 2010 11:02:39 -0800 |
parents | a61af66fc99e |
children | c18cbe5936b8 |
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1293:51db1e4b379d | 1294:7de45b5044c3 |
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51 size_t num_symbols; | 51 size_t num_symbols; |
52 struct elf_symbol *symbols; | 52 struct elf_symbol *symbols; |
53 struct hsearch_data *hash_table; | 53 struct hsearch_data *hash_table; |
54 } symtab_t; | 54 } symtab_t; |
55 | 55 |
56 // read symbol table from given fd. | 56 |
57 struct symtab* build_symtab(int fd) { | 57 // Directory that contains global debuginfo files. In theory it |
58 // should be possible to change this, but in a Java environment there | |
59 // is no obvious place to put a user interface to do it. Maybe this | |
60 // could be set with an environment variable. | |
61 static const char debug_file_directory[] = "/usr/lib/debug"; | |
62 | |
63 /* The CRC used in gnu_debuglink, retrieved from | |
64 http://sourceware.org/gdb/current/onlinedocs/gdb/Separate-Debug-Files.html#Separate-Debug-Files. */ | |
65 unsigned int gnu_debuglink_crc32 (unsigned int crc, | |
66 unsigned char *buf, size_t len) | |
67 { | |
68 static const unsigned int crc32_table[256] = | |
69 { | |
70 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, | |
71 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, | |
72 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, | |
73 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, | |
74 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856, | |
75 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, | |
76 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, | |
77 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, | |
78 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, | |
79 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a, | |
80 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, | |
81 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, | |
82 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, | |
83 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, | |
84 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e, | |
85 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, | |
86 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, | |
87 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, | |
88 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, | |
89 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, | |
90 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, | |
91 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, | |
92 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, | |
93 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, | |
94 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, | |
95 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, | |
96 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, | |
97 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, | |
98 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344, | |
99 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, | |
100 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, | |
101 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, | |
102 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, | |
103 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c, | |
104 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, | |
105 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, | |
106 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, | |
107 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, | |
108 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c, | |
109 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, | |
110 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, | |
111 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, | |
112 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, | |
113 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, | |
114 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, | |
115 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, | |
116 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66, | |
117 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, | |
118 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, | |
119 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, | |
120 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, | |
121 0x2d02ef8d | |
122 }; | |
123 unsigned char *end; | |
124 | |
125 crc = ~crc & 0xffffffff; | |
126 for (end = buf + len; buf < end; ++buf) | |
127 crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8); | |
128 return ~crc & 0xffffffff; | |
129 } | |
130 | |
131 /* Open a debuginfo file and check its CRC. If it exists and the CRC | |
132 matches return its fd. */ | |
133 static int | |
134 open_debug_file (const char *pathname, unsigned int crc) | |
135 { | |
136 unsigned int file_crc = 0; | |
137 unsigned char buffer[8 * 1024]; | |
138 | |
139 int fd = pathmap_open(pathname); | |
140 | |
141 if (fd < 0) | |
142 return -1; | |
143 | |
144 lseek(fd, 0, SEEK_SET); | |
145 | |
146 for (;;) { | |
147 int len = read(fd, buffer, sizeof buffer); | |
148 if (len <= 0) | |
149 break; | |
150 file_crc = gnu_debuglink_crc32(file_crc, buffer, len); | |
151 } | |
152 | |
153 if (crc == file_crc) | |
154 return fd; | |
155 else { | |
156 close(fd); | |
157 return -1; | |
158 } | |
159 } | |
160 | |
161 /* Find an ELF section. */ | |
162 static struct elf_section *find_section_by_name(char *name, | |
163 int fd, | |
164 ELF_EHDR *ehdr, | |
165 ELF_SHDR *shbuf, | |
166 struct elf_section *scn_cache) | |
167 { | |
168 ELF_SHDR* cursct = NULL; | |
169 char *strtab; | |
170 int cnt; | |
171 | |
172 if (scn_cache[ehdr->e_shstrndx].c_data == NULL) { | |
173 if ((scn_cache[ehdr->e_shstrndx].c_data | |
174 = read_section_data(fd, ehdr, cursct)) == NULL) { | |
175 return NULL; | |
176 } | |
177 } | |
178 | |
179 strtab = scn_cache[ehdr->e_shstrndx].c_data; | |
180 | |
181 for (cursct = shbuf, cnt = 0; | |
182 cnt < ehdr->e_shnum; | |
183 cnt++, cursct++) { | |
184 if (strcmp(cursct->sh_name + strtab, name) == 0) { | |
185 scn_cache[cnt].c_data = read_section_data(fd, ehdr, cursct); | |
186 return &scn_cache[cnt]; | |
187 } | |
188 } | |
189 | |
190 return NULL; | |
191 } | |
192 | |
193 /* Look for a ".gnu_debuglink" section. If one exists, try to open a | |
194 suitable debuginfo file. */ | |
195 static int open_file_from_debug_link(const char *name, | |
196 int fd, | |
197 ELF_EHDR *ehdr, | |
198 ELF_SHDR *shbuf, | |
199 struct elf_section *scn_cache) | |
200 { | |
201 int debug_fd; | |
202 struct elf_section *debug_link = find_section_by_name(".gnu_debuglink", fd, ehdr, | |
203 shbuf, scn_cache); | |
204 if (debug_link == NULL) | |
205 return -1; | |
206 char *debug_filename = debug_link->c_data; | |
207 int offset = (strlen(debug_filename) + 4) >> 2; | |
208 static unsigned int crc; | |
209 crc = ((unsigned int*)debug_link->c_data)[offset]; | |
210 char *debug_pathname = malloc(strlen(debug_filename) | |
211 + strlen(name) | |
212 + strlen(".debug/") | |
213 + strlen(debug_file_directory) | |
214 + 2); | |
215 strcpy(debug_pathname, name); | |
216 char *last_slash = strrchr(debug_pathname, '/'); | |
217 if (last_slash == NULL) | |
218 return -1; | |
219 | |
220 /* Look in the same directory as the object. */ | |
221 strcpy(last_slash+1, debug_filename); | |
222 | |
223 debug_fd = open_debug_file(debug_pathname, crc); | |
224 if (debug_fd >= 0) { | |
225 free(debug_pathname); | |
226 return debug_fd; | |
227 } | |
228 | |
229 /* Look in a subdirectory named ".debug". */ | |
230 strcpy(last_slash+1, ".debug/"); | |
231 strcat(last_slash, debug_filename); | |
232 | |
233 debug_fd = open_debug_file(debug_pathname, crc); | |
234 if (debug_fd >= 0) { | |
235 free(debug_pathname); | |
236 return debug_fd; | |
237 } | |
238 | |
239 /* Look in /usr/lib/debug + the full pathname. */ | |
240 strcpy(debug_pathname, debug_file_directory); | |
241 strcat(debug_pathname, name); | |
242 last_slash = strrchr(debug_pathname, '/'); | |
243 strcpy(last_slash+1, debug_filename); | |
244 | |
245 debug_fd = open_debug_file(debug_pathname, crc); | |
246 if (debug_fd >= 0) { | |
247 free(debug_pathname); | |
248 return debug_fd; | |
249 } | |
250 | |
251 free(debug_pathname); | |
252 return -1; | |
253 } | |
254 | |
255 static struct symtab* build_symtab_internal(int fd, const char *filename, bool try_debuginfo); | |
256 | |
257 /* Look for a ".gnu_debuglink" section. If one exists, try to open a | |
258 suitable debuginfo file and read a symbol table from it. */ | |
259 static struct symtab *build_symtab_from_debug_link(const char *name, | |
260 int fd, | |
261 ELF_EHDR *ehdr, | |
262 ELF_SHDR *shbuf, | |
263 struct elf_section *scn_cache) | |
264 { | |
265 fd = open_file_from_debug_link(name, fd, ehdr, shbuf, scn_cache); | |
266 | |
267 if (fd >= 0) { | |
268 struct symtab *symtab = build_symtab_internal(fd, NULL, /* try_debuginfo */ false); | |
269 close(fd); | |
270 return symtab; | |
271 } | |
272 | |
273 return NULL; | |
274 } | |
275 | |
276 // Given a build_id, find the associated debuginfo file | |
277 static char * | |
278 build_id_to_debug_filename (size_t size, unsigned char *data) | |
279 { | |
280 char *filename, *s; | |
281 | |
282 filename = malloc(strlen (debug_file_directory) + (sizeof "/.build-id/" - 1) + 1 | |
283 + 2 * size + (sizeof ".debug" - 1) + 1); | |
284 s = filename + sprintf (filename, "%s/.build-id/", debug_file_directory); | |
285 if (size > 0) | |
286 { | |
287 size--; | |
288 s += sprintf (s, "%02x", *data++); | |
289 } | |
290 if (size > 0) | |
291 *s++ = '/'; | |
292 while (size-- > 0) | |
293 s += sprintf (s, "%02x", *data++); | |
294 strcpy (s, ".debug"); | |
295 | |
296 return filename; | |
297 } | |
298 | |
299 // Read a build ID note. Try to open any associated debuginfo file | |
300 // and return its symtab | |
301 static struct symtab* build_symtab_from_build_id(Elf64_Nhdr *note) | |
302 { | |
303 int fd; | |
304 struct symtab *symtab = NULL; | |
305 | |
306 unsigned char *bytes | |
307 = (unsigned char*)(note+1) + note->n_namesz; | |
308 unsigned char *filename | |
309 = (build_id_to_debug_filename (note->n_descsz, bytes)); | |
310 | |
311 fd = pathmap_open(filename); | |
312 if (fd >= 0) { | |
313 symtab = build_symtab_internal(fd, NULL, /* try_debuginfo */ false); | |
314 close(fd); | |
315 } | |
316 free(filename); | |
317 | |
318 return symtab; | |
319 } | |
320 | |
321 // read symbol table from given fd. If try_debuginfo) is true, also | |
322 // try to open an associated debuginfo file | |
323 static struct symtab* build_symtab_internal(int fd, const char *filename, bool try_debuginfo) { | |
58 ELF_EHDR ehdr; | 324 ELF_EHDR ehdr; |
59 char *names = NULL; | 325 char *names = NULL; |
60 struct symtab* symtab = NULL; | 326 struct symtab* symtab = NULL; |
61 | 327 |
62 // Reading of elf header | 328 // Reading of elf header |
64 int cnt = 0; | 330 int cnt = 0; |
65 ELF_SHDR* shbuf = NULL; | 331 ELF_SHDR* shbuf = NULL; |
66 ELF_SHDR* cursct = NULL; | 332 ELF_SHDR* cursct = NULL; |
67 ELF_PHDR* phbuf = NULL; | 333 ELF_PHDR* phbuf = NULL; |
68 ELF_PHDR* phdr = NULL; | 334 ELF_PHDR* phdr = NULL; |
335 int sym_section = SHT_DYNSYM; | |
69 | 336 |
70 uintptr_t baseaddr = (uintptr_t)-1; | 337 uintptr_t baseaddr = (uintptr_t)-1; |
71 | 338 |
72 lseek(fd, (off_t)0L, SEEK_SET); | 339 lseek(fd, (off_t)0L, SEEK_SET); |
73 if (! read_elf_header(fd, &ehdr)) { | 340 if (! read_elf_header(fd, &ehdr)) { |
88 goto quit; | 355 goto quit; |
89 } | 356 } |
90 | 357 |
91 for (cursct = shbuf, cnt = 0; cnt < ehdr.e_shnum; cnt++) { | 358 for (cursct = shbuf, cnt = 0; cnt < ehdr.e_shnum; cnt++) { |
92 scn_cache[cnt].c_shdr = cursct; | 359 scn_cache[cnt].c_shdr = cursct; |
93 if (cursct->sh_type == SHT_SYMTAB || cursct->sh_type == SHT_STRTAB) { | 360 if (cursct->sh_type == SHT_SYMTAB || cursct->sh_type == SHT_STRTAB |
361 || cursct->sh_type == SHT_NOTE || cursct->sh_type == SHT_DYNSYM) { | |
94 if ( (scn_cache[cnt].c_data = read_section_data(fd, &ehdr, cursct)) == NULL) { | 362 if ( (scn_cache[cnt].c_data = read_section_data(fd, &ehdr, cursct)) == NULL) { |
95 goto quit; | 363 goto quit; |
96 } | 364 } |
97 } | 365 } |
366 if (cursct->sh_type == SHT_SYMTAB) { | |
367 // Full symbol table available so use that | |
368 sym_section = cursct->sh_type; | |
369 } | |
98 cursct++; | 370 cursct++; |
99 } | 371 } |
100 | 372 |
101 for (cnt = 1; cnt < ehdr.e_shnum; cnt++) { | 373 for (cnt = 1; cnt < ehdr.e_shnum; cnt++) { |
102 ELF_SHDR *shdr = scn_cache[cnt].c_shdr; | 374 ELF_SHDR *shdr = scn_cache[cnt].c_shdr; |
103 | 375 |
104 if (shdr->sh_type == SHT_SYMTAB) { | 376 if (shdr->sh_type == sym_section) { |
105 ELF_SYM *syms; | 377 ELF_SYM *syms; |
106 int j, n, rslt; | 378 int j, n, rslt; |
107 size_t size; | 379 size_t size; |
108 | 380 |
109 // FIXME: there could be multiple data buffers associated with the | 381 // FIXME: there could be multiple data buffers associated with the |
158 item.key = sym_name; | 430 item.key = sym_name; |
159 item.data = (void *)&(symtab->symbols[j]); | 431 item.data = (void *)&(symtab->symbols[j]); |
160 | 432 |
161 hsearch_r(item, ENTER, &ret, symtab->hash_table); | 433 hsearch_r(item, ENTER, &ret, symtab->hash_table); |
162 } | 434 } |
435 } | |
436 } | |
437 | |
438 // Look for a separate debuginfo file. | |
439 if (try_debuginfo) { | |
440 | |
441 // We prefer a debug symtab to an object's own symtab, so look in | |
442 // the debuginfo file. We stash a copy of the old symtab in case | |
443 // there is no debuginfo. | |
444 struct symtab* prev_symtab = symtab; | |
445 symtab = NULL; | |
446 | |
447 #ifdef NT_GNU_BUILD_ID | |
448 // First we look for a Build ID | |
449 for (cursct = shbuf, cnt = 0; | |
450 symtab == NULL && cnt < ehdr.e_shnum; | |
451 cnt++) { | |
452 if (cursct->sh_type == SHT_NOTE) { | |
453 Elf64_Nhdr *note = (Elf64_Nhdr *)scn_cache[cnt].c_data; | |
454 if (note->n_type == NT_GNU_BUILD_ID) { | |
455 symtab = build_symtab_from_build_id(note); | |
456 } | |
457 } | |
458 cursct++; | |
459 } | |
460 #endif | |
461 | |
462 // Then, if that doesn't work, the debug link | |
463 if (symtab == NULL) { | |
464 symtab = build_symtab_from_debug_link(filename, fd, &ehdr, shbuf, | |
465 scn_cache); | |
466 } | |
467 | |
468 // If we still haven't found a symtab, use the object's own symtab. | |
469 if (symtab != NULL) { | |
470 if (prev_symtab != NULL) | |
471 destroy_symtab(prev_symtab); | |
472 } else { | |
473 symtab = prev_symtab; | |
163 } | 474 } |
164 } | 475 } |
165 | 476 |
166 quit: | 477 quit: |
167 if (shbuf) free(shbuf); | 478 if (shbuf) free(shbuf); |
174 } | 485 } |
175 free(scn_cache); | 486 free(scn_cache); |
176 } | 487 } |
177 return symtab; | 488 return symtab; |
178 } | 489 } |
490 | |
491 struct symtab* build_symtab(int fd, const char *filename) { | |
492 return build_symtab_internal(fd, filename, /* try_debuginfo */ true); | |
493 } | |
494 | |
179 | 495 |
180 void destroy_symtab(struct symtab* symtab) { | 496 void destroy_symtab(struct symtab* symtab) { |
181 if (!symtab) return; | 497 if (!symtab) return; |
182 if (symtab->strs) free(symtab->strs); | 498 if (symtab->strs) free(symtab->strs); |
183 if (symtab->symbols) free(symtab->symbols); | 499 if (symtab->symbols) free(symtab->symbols); |