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1ab3bf1b JG |
1 | /* GDB routines for manipulating the minimal symbol tables. |
2 | Copyright 1992 Free Software Foundation, Inc. | |
3 | Contributed by Cygnus Support, using pieces from other GDB modules. | |
4 | ||
5 | This file is part of GDB. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program; if not, write to the Free Software | |
19 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
20 | ||
21 | ||
22 | /* This file contains support routines for creating, manipulating, and | |
23 | destroying minimal symbol tables. | |
24 | ||
25 | Minimal symbol tables are used to hold some very basic information about | |
26 | all defined global symbols (text, data, bss, abs, etc). The only two | |
27 | required pieces of information are the symbol's name and the address | |
28 | associated with that symbol. | |
29 | ||
30 | In many cases, even if a file was compiled with no special options for | |
31 | debugging at all, as long as was not stripped it will contain sufficient | |
32 | information to build useful minimal symbol tables using this structure. | |
33 | ||
34 | Even when a file contains enough debugging information to build a full | |
35 | symbol table, these minimal symbols are still useful for quickly mapping | |
36 | between names and addresses, and vice versa. They are also sometimes used | |
37 | to figure out what full symbol table entries need to be read in. */ | |
38 | ||
39 | ||
1ab3bf1b JG |
40 | #include "defs.h" |
41 | #include "symtab.h" | |
42 | #include "bfd.h" | |
43 | #include "symfile.h" | |
44 | ||
45 | /* Accumulate the minimal symbols for each objfile in bunches of BUNCH_SIZE. | |
46 | At the end, copy them all into one newly allocated location on an objfile's | |
47 | symbol obstack. */ | |
48 | ||
49 | #define BUNCH_SIZE 127 | |
50 | ||
51 | struct msym_bunch | |
52 | { | |
53 | struct msym_bunch *next; | |
54 | struct minimal_symbol contents[BUNCH_SIZE]; | |
55 | }; | |
56 | ||
57 | /* Bunch currently being filled up. | |
58 | The next field points to chain of filled bunches. */ | |
59 | ||
60 | static struct msym_bunch *msym_bunch; | |
61 | ||
62 | /* Number of slots filled in current bunch. */ | |
63 | ||
64 | static int msym_bunch_index; | |
65 | ||
66 | /* Total number of minimal symbols recorded so far for the objfile. */ | |
67 | ||
68 | static int msym_count; | |
69 | ||
70 | /* Prototypes for local functions. */ | |
71 | ||
72 | static int | |
73 | compare_minimal_symbols PARAMS ((const void *, const void *)); | |
74 | ||
75 | static int | |
76 | compact_minimal_symbols PARAMS ((struct minimal_symbol *, int)); | |
77 | ||
78 | /* Call the function specified by FUNC for each currently available minimal | |
79 | symbol, for as long as this function continues to return NULL. If the | |
80 | function ever returns non-NULL, then the iteration over the minimal | |
318bf84f | 81 | symbols is terminated and the result is returned to the caller. |
1ab3bf1b JG |
82 | |
83 | The function called has full control over the form and content of the | |
84 | information returned via the non-NULL result, which may be as simple as a | |
85 | pointer to the minimal symbol that the iteration terminated on, or as | |
86 | complex as a pointer to a private structure containing multiple results. */ | |
87 | ||
88 | PTR | |
89 | iterate_over_msymbols (func, arg1, arg2, arg3) | |
90 | PTR (*func) PARAMS ((struct objfile *, struct minimal_symbol *, | |
91 | PTR, PTR, PTR)); | |
92 | PTR arg1; | |
93 | PTR arg2; | |
94 | PTR arg3; | |
95 | { | |
96 | register struct objfile *objfile; | |
97 | register struct minimal_symbol *msymbol; | |
98 | char *result = NULL; | |
99 | ||
100 | for (objfile = object_files; | |
101 | objfile != NULL && result == NULL; | |
102 | objfile = objfile -> next) | |
103 | { | |
104 | for (msymbol = objfile -> msymbols; | |
105 | msymbol != NULL && msymbol -> name != NULL && result == NULL; | |
106 | msymbol++) | |
107 | { | |
108 | result = (*func)(objfile, msymbol, arg1, arg2, arg3); | |
109 | } | |
110 | } | |
111 | return (result); | |
112 | } | |
113 | ||
114 | /* Look through all the current minimal symbol tables and find the first | |
115 | minimal symbol that matches NAME. If OBJF is non-NULL, it specifies a | |
116 | particular objfile and the search is limited to that objfile. Returns | |
117 | a pointer to the minimal symbol that matches, or NULL if no match is found. | |
118 | ||
507e4004 | 119 | Note: One instance where there may be duplicate minimal symbols with |
1ab3bf1b JG |
120 | the same name is when the symbol tables for a shared library and the |
121 | symbol tables for an executable contain global symbols with the same | |
122 | names (the dynamic linker deals with the duplication). */ | |
123 | ||
124 | struct minimal_symbol * | |
125 | lookup_minimal_symbol (name, objf) | |
126 | register const char *name; | |
127 | struct objfile *objf; | |
128 | { | |
129 | struct objfile *objfile; | |
130 | struct minimal_symbol *msymbol; | |
131 | struct minimal_symbol *found_symbol = NULL; | |
507e4004 PB |
132 | #ifdef IBM6000 |
133 | struct minimal_symbol *trampoline_symbol = NULL; | |
134 | #endif | |
1ab3bf1b JG |
135 | |
136 | for (objfile = object_files; | |
137 | objfile != NULL && found_symbol == NULL; | |
138 | objfile = objfile -> next) | |
139 | { | |
140 | if (objf == NULL || objf == objfile) | |
141 | { | |
142 | for (msymbol = objfile -> msymbols; | |
143 | msymbol != NULL && msymbol -> name != NULL && | |
144 | found_symbol == NULL; | |
145 | msymbol++) | |
146 | { | |
147 | if (strcmp (msymbol -> name, name) == 0) | |
148 | { | |
507e4004 PB |
149 | /* I *think* all platforms using shared libraries (and trampoline code) |
150 | * will suffer this problem. Consider a case where there are 5 shared | |
151 | * libraries, each referencing `foo' with a trampoline entry. When someone | |
152 | * wants to put a breakpoint on `foo' and the only info we have is minimal | |
153 | * symbol vector, we want to use the real `foo', rather than one of those | |
154 | * trampoline entries. MGO */ | |
155 | #ifdef IBM6000 | |
156 | /* If a trampoline symbol is found, we prefer to keep looking | |
157 | for the *real* symbol. If the actual symbol not found, | |
158 | then we'll use the trampoline entry. Sorry for the machine | |
159 | dependent code here, but I hope this will benefit other | |
160 | platforms as well. For trampoline entries, we used mst_unknown | |
161 | earlier. Perhaps we should define a `mst_trampoline' type?? */ | |
162 | ||
163 | if (msymbol->type != mst_unknown) | |
164 | found_symbol = msymbol; | |
165 | else if (msymbol->type == mst_unknown && !trampoline_symbol) | |
166 | trampoline_symbol = msymbol; | |
167 | ||
168 | #else | |
1ab3bf1b | 169 | found_symbol = msymbol; |
507e4004 | 170 | #endif |
1ab3bf1b JG |
171 | } |
172 | } | |
173 | } | |
174 | } | |
507e4004 PB |
175 | #ifdef IBM6000 |
176 | return found_symbol ? found_symbol : trampoline_symbol; | |
177 | #endif | |
178 | ||
1ab3bf1b JG |
179 | return (found_symbol); |
180 | } | |
181 | ||
182 | ||
183 | /* Search through the minimal symbol table for each objfile and find the | |
184 | symbol whose address is the largest address that is still less than or | |
185 | equal to PC. Returns a pointer to the minimal symbol if such a symbol | |
186 | is found, or NULL if PC is not in a suitable range. Note that we need | |
187 | to look through ALL the minimal symbol tables before deciding on the | |
188 | symbol that comes closest to the specified PC. */ | |
189 | ||
190 | struct minimal_symbol * | |
191 | lookup_minimal_symbol_by_pc (pc) | |
192 | register CORE_ADDR pc; | |
193 | { | |
194 | register int lo; | |
195 | register int hi; | |
196 | register int new; | |
197 | register struct objfile *objfile; | |
198 | register struct minimal_symbol *msymbol; | |
199 | register struct minimal_symbol *best_symbol = NULL; | |
200 | ||
201 | for (objfile = object_files; | |
202 | objfile != NULL; | |
203 | objfile = objfile -> next) | |
204 | { | |
205 | /* If this objfile has a minimal symbol table, go search it using | |
206 | a binary search. Note that a minimal symbol table always consists | |
207 | of at least two symbols, a "real" symbol and the terminating | |
208 | "null symbol". If there are no real symbols, then there is no | |
209 | minimal symbol table at all. */ | |
210 | ||
211 | if ((msymbol = objfile -> msymbols) != NULL) | |
212 | { | |
213 | lo = 0; | |
214 | hi = objfile -> minimal_symbol_count - 2; | |
215 | ||
216 | /* This code assumes that the minimal symbols are sorted by | |
217 | ascending address values. If the pc value is greater than or | |
218 | equal to the first symbol's address, then some symbol in this | |
219 | minimal symbol table is a suitable candidate for being the | |
220 | "best" symbol. This includes the last real symbol, for cases | |
221 | where the pc value is larger than any address in this vector. | |
222 | ||
223 | By iterating until the address associated with the current | |
224 | hi index (the endpoint of the test interval) is less than | |
225 | or equal to the desired pc value, we accomplish two things: | |
226 | (1) the case where the pc value is larger than any minimal | |
227 | symbol address is trivially solved, (2) the address associated | |
228 | with the hi index is always the one we want when the interation | |
229 | terminates. In essence, we are iterating the test interval | |
230 | down until the pc value is pushed out of it from the high end. | |
231 | ||
232 | Warning: this code is trickier than it would appear at first. */ | |
233 | ||
234 | if (pc >= msymbol[lo].address) | |
235 | { | |
236 | while (msymbol[hi].address > pc) | |
237 | { | |
238 | /* pc is still strictly less than highest address */ | |
239 | /* Note "new" will always be >= lo */ | |
240 | new = (lo + hi) / 2; | |
241 | if ((msymbol[new].address >= pc) || (lo == new)) | |
242 | { | |
243 | hi = new; | |
244 | } | |
245 | else | |
246 | { | |
247 | lo = new; | |
248 | } | |
249 | } | |
250 | /* The minimal symbol indexed by hi now is the best one in this | |
251 | objfile's minimal symbol table. See if it is the best one | |
252 | overall. */ | |
253 | ||
254 | if ((best_symbol == NULL) || | |
255 | (best_symbol -> address < msymbol[hi].address)) | |
256 | { | |
257 | best_symbol = &msymbol[hi]; | |
258 | } | |
259 | } | |
260 | } | |
261 | } | |
262 | return (best_symbol); | |
263 | } | |
264 | ||
265 | /* Prepare to start collecting minimal symbols. Note that presetting | |
266 | msym_bunch_index to BUNCH_SIZE causes the first call to save a minimal | |
267 | symbol to allocate the memory for the first bunch. */ | |
268 | ||
269 | void | |
270 | init_minimal_symbol_collection () | |
271 | { | |
272 | msym_count = 0; | |
273 | msym_bunch = NULL; | |
274 | msym_bunch_index = BUNCH_SIZE; | |
275 | } | |
276 | ||
277 | void | |
278 | prim_record_minimal_symbol (name, address, ms_type) | |
279 | const char *name; | |
280 | CORE_ADDR address; | |
281 | enum minimal_symbol_type ms_type; | |
282 | { | |
283 | register struct msym_bunch *new; | |
284 | ||
285 | if (msym_bunch_index == BUNCH_SIZE) | |
286 | { | |
287 | new = (struct msym_bunch *) xmalloc (sizeof (struct msym_bunch)); | |
288 | msym_bunch_index = 0; | |
289 | new -> next = msym_bunch; | |
290 | msym_bunch = new; | |
291 | } | |
292 | msym_bunch -> contents[msym_bunch_index].name = (char *) name; | |
293 | msym_bunch -> contents[msym_bunch_index].address = address; | |
294 | msym_bunch -> contents[msym_bunch_index].info = NULL; | |
295 | msym_bunch -> contents[msym_bunch_index].type = ms_type; | |
296 | msym_bunch_index++; | |
297 | msym_count++; | |
298 | } | |
299 | ||
300 | /* Compare two minimal symbols by address and return a signed result based | |
301 | on unsigned comparisons, so that we sort into unsigned numeric order. */ | |
302 | ||
303 | static int | |
304 | compare_minimal_symbols (fn1p, fn2p) | |
305 | const PTR fn1p; | |
306 | const PTR fn2p; | |
307 | { | |
308 | register const struct minimal_symbol *fn1; | |
309 | register const struct minimal_symbol *fn2; | |
310 | ||
311 | fn1 = (const struct minimal_symbol *) fn1p; | |
312 | fn2 = (const struct minimal_symbol *) fn2p; | |
313 | ||
314 | if (fn1 -> address < fn2 -> address) | |
315 | { | |
316 | return (-1); | |
317 | } | |
318 | else if (fn1 -> address > fn2 -> address) | |
319 | { | |
320 | return (1); | |
321 | } | |
322 | else | |
323 | { | |
324 | return (0); | |
325 | } | |
326 | } | |
327 | ||
328 | /* Discard the currently collected minimal symbols, if any. If we wish | |
329 | to save them for later use, we must have already copied them somewhere | |
330 | else before calling this function. | |
331 | ||
332 | FIXME: We could allocate the minimal symbol bunches on their own | |
333 | obstack and then simply blow the obstack away when we are done with | |
334 | it. Is it worth the extra trouble though? */ | |
335 | ||
336 | /* ARGSUSED */ | |
337 | void | |
338 | discard_minimal_symbols (foo) | |
339 | int foo; | |
340 | { | |
341 | register struct msym_bunch *next; | |
342 | ||
343 | while (msym_bunch != NULL) | |
344 | { | |
345 | next = msym_bunch -> next; | |
346 | free (msym_bunch); | |
347 | msym_bunch = next; | |
348 | } | |
349 | } | |
350 | ||
351 | /* Compact duplicate entries out of a minimal symbol table by walking | |
352 | through the table and compacting out entries with duplicate addresses | |
021959e2 JG |
353 | and matching names. Return the number of entries remaining. |
354 | ||
355 | On entry, the table resides between msymbol[0] and msymbol[mcount]. | |
356 | On exit, it resides between msymbol[0] and msymbol[result_count]. | |
1ab3bf1b JG |
357 | |
358 | When files contain multiple sources of symbol information, it is | |
359 | possible for the minimal symbol table to contain many duplicate entries. | |
360 | As an example, SVR4 systems use ELF formatted object files, which | |
361 | usually contain at least two different types of symbol tables (a | |
362 | standard ELF one and a smaller dynamic linking table), as well as | |
363 | DWARF debugging information for files compiled with -g. | |
364 | ||
365 | Without compacting, the minimal symbol table for gdb itself contains | |
366 | over a 1000 duplicates, about a third of the total table size. Aside | |
367 | from the potential trap of not noticing that two successive entries | |
368 | identify the same location, this duplication impacts the time required | |
021959e2 | 369 | to linearly scan the table, which is done in a number of places. So we |
1ab3bf1b JG |
370 | just do one linear scan here and toss out the duplicates. |
371 | ||
372 | Note that we are not concerned here about recovering the space that | |
373 | is potentially freed up, because the strings themselves are allocated | |
374 | on the symbol_obstack, and will get automatically freed when the symbol | |
021959e2 JG |
375 | table is freed. The caller can free up the unused minimal symbols at |
376 | the end of the compacted region if their allocation strategy allows it. | |
1ab3bf1b JG |
377 | |
378 | Also note we only go up to the next to last entry within the loop | |
379 | and then copy the last entry explicitly after the loop terminates. | |
380 | ||
381 | Since the different sources of information for each symbol may | |
382 | have different levels of "completeness", we may have duplicates | |
383 | that have one entry with type "mst_unknown" and the other with a | |
384 | known type. So if the one we are leaving alone has type mst_unknown, | |
385 | overwrite its type with the type from the one we are compacting out. */ | |
386 | ||
387 | static int | |
388 | compact_minimal_symbols (msymbol, mcount) | |
389 | struct minimal_symbol *msymbol; | |
390 | int mcount; | |
391 | { | |
392 | struct minimal_symbol *copyfrom; | |
393 | struct minimal_symbol *copyto; | |
394 | ||
395 | if (mcount > 0) | |
396 | { | |
397 | copyfrom = copyto = msymbol; | |
398 | while (copyfrom < msymbol + mcount - 1) | |
399 | { | |
400 | if (copyfrom -> address == (copyfrom + 1) -> address | |
401 | && (strcmp (copyfrom -> name, (copyfrom + 1) -> name) == 0)) | |
402 | { | |
403 | if ((copyfrom + 1) -> type == mst_unknown) | |
404 | { | |
405 | (copyfrom + 1) -> type = copyfrom -> type; | |
406 | } | |
407 | copyfrom++; | |
408 | } | |
409 | else | |
410 | { | |
411 | *copyto++ = *copyfrom++; | |
412 | } | |
413 | } | |
414 | *copyto++ = *copyfrom++; | |
415 | mcount = copyto - msymbol; | |
416 | } | |
417 | return (mcount); | |
418 | } | |
419 | ||
021959e2 JG |
420 | /* Add the minimal symbols in the existing bunches to the objfile's |
421 | official minimal symbol table. 99% of the time, this adds the | |
422 | bunches to NO existing symbols. Once in a while for shared | |
423 | libraries, we add symbols (e.g. common symbols) to an existing | |
424 | objfile. */ | |
1ab3bf1b JG |
425 | |
426 | void | |
021959e2 | 427 | install_minimal_symbols (objfile) |
1ab3bf1b JG |
428 | struct objfile *objfile; |
429 | { | |
430 | register int bindex; | |
431 | register int mcount; | |
432 | register struct msym_bunch *bunch; | |
433 | register struct minimal_symbol *msymbols; | |
021959e2 | 434 | int alloc_count; |
1ab3bf1b JG |
435 | |
436 | if (msym_count > 0) | |
437 | { | |
021959e2 JG |
438 | /* Allocate enough space in the obstack, into which we will gather the |
439 | bunches of new and existing minimal symbols, sort them, and then | |
440 | compact out the duplicate entries. Once we have a final table, | |
441 | we will give back the excess space. */ | |
442 | ||
443 | alloc_count = msym_count + objfile->minimal_symbol_count + 1; | |
444 | obstack_blank (&objfile->symbol_obstack, | |
445 | alloc_count * sizeof (struct minimal_symbol)); | |
1ab3bf1b | 446 | msymbols = (struct minimal_symbol *) |
021959e2 JG |
447 | obstack_base (&objfile->symbol_obstack); |
448 | ||
449 | /* Copy in the existing minimal symbols, if there are any. */ | |
450 | ||
451 | if (objfile->minimal_symbol_count) | |
452 | memcpy ((char *)msymbols, (char *)objfile->msymbols, | |
453 | objfile->minimal_symbol_count * sizeof (struct minimal_symbol)); | |
454 | ||
1ab3bf1b JG |
455 | /* Walk through the list of minimal symbol bunches, adding each symbol |
456 | to the new contiguous array of symbols. Note that we start with the | |
457 | current, possibly partially filled bunch (thus we use the current | |
458 | msym_bunch_index for the first bunch we copy over), and thereafter | |
459 | each bunch is full. */ | |
460 | ||
021959e2 JG |
461 | mcount = objfile->minimal_symbol_count; |
462 | ||
1ab3bf1b JG |
463 | for (bunch = msym_bunch; bunch != NULL; bunch = bunch -> next) |
464 | { | |
465 | for (bindex = 0; bindex < msym_bunch_index; bindex++, mcount++) | |
466 | { | |
467 | msymbols[mcount] = bunch -> contents[bindex]; | |
468 | #ifdef NAMES_HAVE_UNDERSCORE | |
469 | if (msymbols[mcount].name[0] == '_') | |
470 | { | |
471 | msymbols[mcount].name++; | |
472 | } | |
473 | #endif | |
474 | #ifdef SOME_NAMES_HAVE_DOT | |
475 | if (msymbols[mcount].name[0] == '.') | |
476 | { | |
477 | msymbols[mcount].name++; | |
478 | } | |
479 | #endif | |
480 | } | |
481 | msym_bunch_index = BUNCH_SIZE; | |
482 | } | |
021959e2 | 483 | |
1ab3bf1b JG |
484 | /* Sort the minimal symbols by address. */ |
485 | ||
486 | qsort (msymbols, mcount, sizeof (struct minimal_symbol), | |
487 | compare_minimal_symbols); | |
488 | ||
021959e2 JG |
489 | /* Compact out any duplicates, and free up whatever space we are |
490 | no longer using. */ | |
1ab3bf1b JG |
491 | |
492 | mcount = compact_minimal_symbols (msymbols, mcount); | |
1ab3bf1b | 493 | |
021959e2 JG |
494 | obstack_blank (&objfile->symbol_obstack, |
495 | (mcount + 1 - alloc_count) * sizeof (struct minimal_symbol)); | |
496 | msymbols = (struct minimal_symbol *) | |
497 | obstack_finish (&objfile->symbol_obstack); | |
498 | ||
499 | /* We also terminate the minimal symbol table | |
500 | with a "null symbol", which is *not* included in the size of | |
501 | the table. This makes it easier to find the end of the table | |
502 | when we are handed a pointer to some symbol in the middle of it. | |
503 | Zero out the fields in the "null symbol" allocated at the end | |
1ab3bf1b JG |
504 | of the array. Note that the symbol count does *not* include |
505 | this null symbol, which is why it is indexed by mcount and not | |
506 | mcount-1. */ | |
507 | ||
021959e2 JG |
508 | msymbols[mcount].name = NULL; |
509 | msymbols[mcount].address = 0; | |
510 | msymbols[mcount].info = NULL; | |
511 | msymbols[mcount].type = mst_unknown; | |
512 | ||
513 | /* Attach the minimal symbol table to the specified objfile. | |
514 | The strings themselves are also located in the symbol_obstack | |
515 | of this objfile. */ | |
516 | ||
517 | objfile -> minimal_symbol_count = mcount; | |
518 | objfile -> msymbols = msymbols; | |
1ab3bf1b JG |
519 | } |
520 | } | |
521 |