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cfc14b3a MK |
1 | /* Frame unwinder for frames with DWARF Call Frame Information. |
2 | ||
3 | Copyright 2003 Free Software Foundation, Inc. | |
4 | ||
5 | Contributed by Mark Kettenis. | |
6 | ||
7 | This file is part of GDB. | |
8 | ||
9 | This program is free software; you can redistribute it and/or modify | |
10 | it under the terms of the GNU General Public License as published by | |
11 | the Free Software Foundation; either version 2 of the License, or | |
12 | (at your option) any later version. | |
13 | ||
14 | This program is distributed in the hope that it will be useful, | |
15 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | GNU General Public License for more details. | |
18 | ||
19 | You should have received a copy of the GNU General Public License | |
20 | along with this program; if not, write to the Free Software | |
21 | Foundation, Inc., 59 Temple Place - Suite 330, | |
22 | Boston, MA 02111-1307, USA. */ | |
23 | ||
24 | #include "defs.h" | |
25 | #include "dwarf2expr.h" | |
26 | #include "elf/dwarf2.h" | |
27 | #include "frame.h" | |
28 | #include "frame-base.h" | |
29 | #include "frame-unwind.h" | |
30 | #include "gdbcore.h" | |
31 | #include "gdbtypes.h" | |
32 | #include "symtab.h" | |
33 | #include "objfiles.h" | |
34 | #include "regcache.h" | |
35 | ||
36 | #include "gdb_assert.h" | |
37 | #include "gdb_string.h" | |
38 | ||
39 | #include "dwarf2-frame.h" | |
40 | ||
41 | /* Call Frame Information (CFI). */ | |
42 | ||
43 | /* Common Information Entry (CIE). */ | |
44 | ||
45 | struct dwarf2_cie | |
46 | { | |
47 | /* Offset into the .debug_frame section where this CIE was found. | |
48 | Used to identify this CIE. */ | |
49 | ULONGEST cie_pointer; | |
50 | ||
51 | /* Constant that is factored out of all advance location | |
52 | instructions. */ | |
53 | ULONGEST code_alignment_factor; | |
54 | ||
55 | /* Constants that is factored out of all offset instructions. */ | |
56 | LONGEST data_alignment_factor; | |
57 | ||
58 | /* Return address column. */ | |
59 | ULONGEST return_address_register; | |
60 | ||
61 | /* Instruction sequence to initialize a register set. */ | |
62 | unsigned char *initial_instructions; | |
63 | unsigned char *end; | |
64 | ||
65 | /* Encoding of addresses. */ | |
66 | unsigned char encoding; | |
67 | ||
7131cb6e RH |
68 | /* True if a 'z' augmentation existed. */ |
69 | unsigned char saw_z_augmentation; | |
70 | ||
cfc14b3a MK |
71 | struct dwarf2_cie *next; |
72 | }; | |
73 | ||
74 | /* Frame Description Entry (FDE). */ | |
75 | ||
76 | struct dwarf2_fde | |
77 | { | |
78 | /* CIE for this FDE. */ | |
79 | struct dwarf2_cie *cie; | |
80 | ||
81 | /* First location associated with this FDE. */ | |
82 | CORE_ADDR initial_location; | |
83 | ||
84 | /* Number of bytes of program instructions described by this FDE. */ | |
85 | CORE_ADDR address_range; | |
86 | ||
87 | /* Instruction sequence. */ | |
88 | unsigned char *instructions; | |
89 | unsigned char *end; | |
90 | ||
91 | struct dwarf2_fde *next; | |
92 | }; | |
93 | ||
94 | static struct dwarf2_fde *dwarf2_frame_find_fde (CORE_ADDR *pc); | |
95 | \f | |
96 | ||
97 | /* Structure describing a frame state. */ | |
98 | ||
99 | struct dwarf2_frame_state | |
100 | { | |
101 | /* Each register save state can be described in terms of a CFA slot, | |
102 | another register, or a location expression. */ | |
103 | struct dwarf2_frame_state_reg_info | |
104 | { | |
105 | struct dwarf2_frame_state_reg | |
106 | { | |
107 | union { | |
108 | LONGEST offset; | |
109 | ULONGEST reg; | |
110 | unsigned char *exp; | |
111 | } loc; | |
112 | ULONGEST exp_len; | |
113 | enum { | |
114 | REG_UNSAVED, | |
115 | REG_SAVED_OFFSET, | |
116 | REG_SAVED_REG, | |
117 | REG_SAVED_EXP, | |
118 | REG_UNMODIFIED | |
119 | } how; | |
120 | } *reg; | |
121 | int num_regs; | |
122 | ||
123 | /* Used to implement DW_CFA_remember_state. */ | |
124 | struct dwarf2_frame_state_reg_info *prev; | |
125 | } regs; | |
126 | ||
127 | LONGEST cfa_offset; | |
128 | ULONGEST cfa_reg; | |
129 | unsigned char *cfa_exp; | |
130 | enum { | |
131 | CFA_UNSET, | |
132 | CFA_REG_OFFSET, | |
133 | CFA_EXP | |
134 | } cfa_how; | |
135 | ||
136 | /* The PC described by the current frame state. */ | |
137 | CORE_ADDR pc; | |
138 | ||
139 | /* Initial register set from the CIE. | |
140 | Used to implement DW_CFA_restore. */ | |
141 | struct dwarf2_frame_state_reg_info initial; | |
142 | ||
143 | /* The information we care about from the CIE. */ | |
144 | LONGEST data_align; | |
145 | ULONGEST code_align; | |
146 | ULONGEST retaddr_column; | |
147 | }; | |
148 | ||
149 | /* Store the length the expression for the CFA in the `cfa_reg' field, | |
150 | which is unused in that case. */ | |
151 | #define cfa_exp_len cfa_reg | |
152 | ||
153 | /* Assert that the register set RS is large enough to store NUM_REGS | |
154 | columns. If necessary, enlarge the register set. */ | |
155 | ||
156 | static void | |
157 | dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info *rs, | |
158 | int num_regs) | |
159 | { | |
160 | size_t size = sizeof (struct dwarf2_frame_state_reg); | |
161 | ||
162 | if (num_regs <= rs->num_regs) | |
163 | return; | |
164 | ||
165 | rs->reg = (struct dwarf2_frame_state_reg *) | |
166 | xrealloc (rs->reg, num_regs * size); | |
167 | ||
168 | /* Initialize newly allocated registers. */ | |
2473a4a9 | 169 | memset (rs->reg + rs->num_regs, 0, (num_regs - rs->num_regs) * size); |
cfc14b3a MK |
170 | rs->num_regs = num_regs; |
171 | } | |
172 | ||
173 | /* Copy the register columns in register set RS into newly allocated | |
174 | memory and return a pointer to this newly created copy. */ | |
175 | ||
176 | static struct dwarf2_frame_state_reg * | |
177 | dwarf2_frame_state_copy_regs (struct dwarf2_frame_state_reg_info *rs) | |
178 | { | |
179 | size_t size = rs->num_regs * sizeof (struct dwarf2_frame_state_reg_info); | |
180 | struct dwarf2_frame_state_reg *reg; | |
181 | ||
182 | reg = (struct dwarf2_frame_state_reg *) xmalloc (size); | |
183 | memcpy (reg, rs->reg, size); | |
184 | ||
185 | return reg; | |
186 | } | |
187 | ||
188 | /* Release the memory allocated to register set RS. */ | |
189 | ||
190 | static void | |
191 | dwarf2_frame_state_free_regs (struct dwarf2_frame_state_reg_info *rs) | |
192 | { | |
193 | if (rs) | |
194 | { | |
195 | dwarf2_frame_state_free_regs (rs->prev); | |
196 | ||
197 | xfree (rs->reg); | |
198 | xfree (rs); | |
199 | } | |
200 | } | |
201 | ||
202 | /* Release the memory allocated to the frame state FS. */ | |
203 | ||
204 | static void | |
205 | dwarf2_frame_state_free (void *p) | |
206 | { | |
207 | struct dwarf2_frame_state *fs = p; | |
208 | ||
209 | dwarf2_frame_state_free_regs (fs->initial.prev); | |
210 | dwarf2_frame_state_free_regs (fs->regs.prev); | |
211 | xfree (fs->initial.reg); | |
212 | xfree (fs->regs.reg); | |
213 | xfree (fs); | |
214 | } | |
215 | \f | |
216 | ||
217 | /* Helper functions for execute_stack_op. */ | |
218 | ||
219 | static CORE_ADDR | |
220 | read_reg (void *baton, int reg) | |
221 | { | |
222 | struct frame_info *next_frame = (struct frame_info *) baton; | |
223 | int regnum; | |
224 | char *buf; | |
225 | ||
226 | regnum = DWARF2_REG_TO_REGNUM (reg); | |
227 | ||
228 | buf = (char *) alloca (register_size (current_gdbarch, regnum)); | |
229 | frame_unwind_register (next_frame, regnum, buf); | |
230 | return extract_typed_address (buf, builtin_type_void_data_ptr); | |
231 | } | |
232 | ||
233 | static void | |
234 | read_mem (void *baton, char *buf, CORE_ADDR addr, size_t len) | |
235 | { | |
236 | read_memory (addr, buf, len); | |
237 | } | |
238 | ||
239 | static void | |
240 | no_get_frame_base (void *baton, unsigned char **start, size_t *length) | |
241 | { | |
242 | internal_error (__FILE__, __LINE__, | |
243 | "Support for DW_OP_fbreg is unimplemented"); | |
244 | } | |
245 | ||
246 | static CORE_ADDR | |
247 | no_get_tls_address (void *baton, CORE_ADDR offset) | |
248 | { | |
249 | internal_error (__FILE__, __LINE__, | |
250 | "Support for DW_OP_GNU_push_tls_address is unimplemented"); | |
251 | } | |
252 | ||
253 | static CORE_ADDR | |
254 | execute_stack_op (unsigned char *exp, ULONGEST len, | |
255 | struct frame_info *next_frame, CORE_ADDR initial) | |
256 | { | |
257 | struct dwarf_expr_context *ctx; | |
258 | CORE_ADDR result; | |
259 | ||
260 | ctx = new_dwarf_expr_context (); | |
261 | ctx->baton = next_frame; | |
262 | ctx->read_reg = read_reg; | |
263 | ctx->read_mem = read_mem; | |
264 | ctx->get_frame_base = no_get_frame_base; | |
265 | ctx->get_tls_address = no_get_tls_address; | |
266 | ||
267 | dwarf_expr_push (ctx, initial); | |
268 | dwarf_expr_eval (ctx, exp, len); | |
269 | result = dwarf_expr_fetch (ctx, 0); | |
270 | ||
271 | if (ctx->in_reg) | |
272 | result = read_reg (next_frame, result); | |
273 | ||
274 | free_dwarf_expr_context (ctx); | |
275 | ||
276 | return result; | |
277 | } | |
278 | \f | |
279 | ||
280 | static void | |
281 | execute_cfa_program (unsigned char *insn_ptr, unsigned char *insn_end, | |
282 | struct frame_info *next_frame, | |
283 | struct dwarf2_frame_state *fs) | |
284 | { | |
285 | CORE_ADDR pc = frame_pc_unwind (next_frame); | |
286 | int bytes_read; | |
287 | ||
288 | while (insn_ptr < insn_end && fs->pc <= pc) | |
289 | { | |
290 | unsigned char insn = *insn_ptr++; | |
291 | ULONGEST utmp, reg; | |
292 | LONGEST offset; | |
293 | ||
294 | if ((insn & 0xc0) == DW_CFA_advance_loc) | |
295 | fs->pc += (insn & 0x3f) * fs->code_align; | |
296 | else if ((insn & 0xc0) == DW_CFA_offset) | |
297 | { | |
298 | reg = insn & 0x3f; | |
299 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); | |
300 | offset = utmp * fs->data_align; | |
301 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); | |
302 | fs->regs.reg[reg].how = REG_SAVED_OFFSET; | |
303 | fs->regs.reg[reg].loc.offset = offset; | |
304 | } | |
305 | else if ((insn & 0xc0) == DW_CFA_restore) | |
306 | { | |
307 | gdb_assert (fs->initial.reg); | |
308 | reg = insn & 0x3f; | |
309 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); | |
310 | fs->regs.reg[reg] = fs->initial.reg[reg]; | |
311 | } | |
312 | else | |
313 | { | |
314 | switch (insn) | |
315 | { | |
316 | case DW_CFA_set_loc: | |
317 | fs->pc = dwarf2_read_address (insn_ptr, insn_end, &bytes_read); | |
318 | insn_ptr += bytes_read; | |
319 | break; | |
320 | ||
321 | case DW_CFA_advance_loc1: | |
322 | utmp = extract_unsigned_integer (insn_ptr, 1); | |
323 | fs->pc += utmp * fs->code_align; | |
324 | insn_ptr++; | |
325 | break; | |
326 | case DW_CFA_advance_loc2: | |
327 | utmp = extract_unsigned_integer (insn_ptr, 2); | |
328 | fs->pc += utmp * fs->code_align; | |
329 | insn_ptr += 2; | |
330 | break; | |
331 | case DW_CFA_advance_loc4: | |
332 | utmp = extract_unsigned_integer (insn_ptr, 4); | |
333 | fs->pc += utmp * fs->code_align; | |
334 | insn_ptr += 4; | |
335 | break; | |
336 | ||
337 | case DW_CFA_offset_extended: | |
338 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); | |
339 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); | |
340 | offset = utmp * fs->data_align; | |
341 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); | |
342 | fs->regs.reg[reg].how = REG_SAVED_OFFSET; | |
343 | fs->regs.reg[reg].loc.offset = offset; | |
344 | break; | |
345 | ||
346 | case DW_CFA_restore_extended: | |
347 | gdb_assert (fs->initial.reg); | |
348 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); | |
349 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); | |
350 | fs->regs.reg[reg] = fs->initial.reg[reg]; | |
351 | break; | |
352 | ||
353 | case DW_CFA_undefined: | |
354 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); | |
355 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); | |
356 | fs->regs.reg[reg].how = REG_UNSAVED; | |
357 | break; | |
358 | ||
359 | case DW_CFA_same_value: | |
360 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); | |
361 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); | |
362 | fs->regs.reg[reg].how = REG_UNMODIFIED; | |
363 | break; | |
364 | ||
365 | case DW_CFA_register: | |
366 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); | |
367 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); | |
368 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); | |
369 | fs->regs.reg[reg].loc.reg = utmp; | |
370 | break; | |
371 | ||
372 | case DW_CFA_remember_state: | |
373 | { | |
374 | struct dwarf2_frame_state_reg_info *new_rs; | |
375 | ||
376 | new_rs = XMALLOC (struct dwarf2_frame_state_reg_info); | |
377 | *new_rs = fs->regs; | |
378 | fs->regs.reg = dwarf2_frame_state_copy_regs (&fs->regs); | |
379 | fs->regs.prev = new_rs; | |
380 | } | |
381 | break; | |
382 | ||
383 | case DW_CFA_restore_state: | |
384 | { | |
385 | struct dwarf2_frame_state_reg_info *old_rs = fs->regs.prev; | |
386 | ||
387 | gdb_assert (old_rs); | |
388 | ||
389 | xfree (fs->regs.reg); | |
390 | fs->regs = *old_rs; | |
391 | xfree (old_rs); | |
392 | } | |
393 | break; | |
394 | ||
395 | case DW_CFA_def_cfa: | |
396 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg); | |
397 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); | |
398 | fs->cfa_offset = utmp; | |
399 | fs->cfa_how = CFA_REG_OFFSET; | |
400 | break; | |
401 | ||
402 | case DW_CFA_def_cfa_register: | |
403 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg); | |
404 | fs->cfa_how = CFA_REG_OFFSET; | |
405 | break; | |
406 | ||
407 | case DW_CFA_def_cfa_offset: | |
408 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_offset); | |
409 | /* cfa_how deliberately not set. */ | |
410 | break; | |
411 | ||
412 | case DW_CFA_def_cfa_expression: | |
413 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_exp_len); | |
414 | fs->cfa_exp = insn_ptr; | |
415 | fs->cfa_how = CFA_EXP; | |
416 | insn_ptr += fs->cfa_exp_len; | |
417 | break; | |
418 | ||
419 | case DW_CFA_expression: | |
420 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); | |
421 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); | |
422 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); | |
423 | fs->regs.reg[reg].loc.exp = insn_ptr; | |
424 | fs->regs.reg[reg].exp_len = utmp; | |
425 | fs->regs.reg[reg].how = REG_SAVED_EXP; | |
426 | insn_ptr += utmp; | |
427 | break; | |
428 | ||
429 | case DW_CFA_nop: | |
430 | break; | |
431 | ||
432 | case DW_CFA_GNU_args_size: | |
433 | /* Ignored. */ | |
434 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); | |
435 | break; | |
436 | ||
437 | default: | |
438 | internal_error (__FILE__, __LINE__, "Unknown CFI encountered."); | |
439 | } | |
440 | } | |
441 | } | |
442 | ||
443 | /* Don't allow remember/restore between CIE and FDE programs. */ | |
444 | dwarf2_frame_state_free_regs (fs->regs.prev); | |
445 | fs->regs.prev = NULL; | |
446 | } | |
447 | ||
448 | struct dwarf2_frame_cache | |
449 | { | |
450 | /* DWARF Call Frame Address. */ | |
451 | CORE_ADDR cfa; | |
452 | ||
453 | /* Saved registers, indexed by GDB register number, not by DWARF | |
454 | register number. */ | |
455 | struct dwarf2_frame_state_reg *reg; | |
456 | }; | |
457 | ||
b9362cc7 | 458 | static struct dwarf2_frame_cache * |
cfc14b3a MK |
459 | dwarf2_frame_cache (struct frame_info *next_frame, void **this_cache) |
460 | { | |
461 | struct cleanup *old_chain; | |
462 | int num_regs = NUM_REGS + NUM_PSEUDO_REGS; | |
463 | struct dwarf2_frame_cache *cache; | |
464 | struct dwarf2_frame_state *fs; | |
465 | struct dwarf2_fde *fde; | |
466 | int reg; | |
467 | ||
468 | if (*this_cache) | |
469 | return *this_cache; | |
470 | ||
471 | /* Allocate a new cache. */ | |
472 | cache = FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache); | |
473 | cache->reg = FRAME_OBSTACK_CALLOC (num_regs, struct dwarf2_frame_state_reg); | |
474 | ||
475 | /* Allocate and initialize the frame state. */ | |
476 | fs = XMALLOC (struct dwarf2_frame_state); | |
477 | memset (fs, 0, sizeof (struct dwarf2_frame_state)); | |
478 | old_chain = make_cleanup (dwarf2_frame_state_free, fs); | |
479 | ||
480 | /* Unwind the PC. | |
481 | ||
482 | Note that if NEXT_FRAME is never supposed to return (i.e. a call | |
483 | to abort), the compiler might optimize away the instruction at | |
484 | NEXT_FRAME's return address. As a result the return address will | |
485 | point at some random instruction, and the CFI for that | |
486 | instruction is probably wortless to us. GCC's unwinder solves | |
487 | this problem by substracting 1 from the return address to get an | |
488 | address in the middle of a presumed call instruction (or the | |
489 | instruction in the associated delay slot). This should only be | |
490 | done for "normal" frames and not for resume-type frames (signal | |
491 | handlers, sentinel frames, dummy frames). | |
492 | ||
493 | We don't do what GCC's does here (yet). It's not clear how | |
494 | reliable the method is. There's also a problem with finding the | |
495 | right FDE; see the comment in dwarf_frame_p. If dwarf_frame_p | |
496 | selected this frame unwinder because it found the FDE for the | |
497 | next function, using the adjusted return address might not yield | |
498 | a FDE at all. The problem isn't specific to DWARF CFI; other | |
499 | unwinders loose in similar ways. Therefore it's probably | |
500 | acceptable to leave things slightly broken for now. */ | |
501 | fs->pc = frame_pc_unwind (next_frame); | |
502 | ||
503 | /* Find the correct FDE. */ | |
504 | fde = dwarf2_frame_find_fde (&fs->pc); | |
505 | gdb_assert (fde != NULL); | |
506 | ||
507 | /* Extract any interesting information from the CIE. */ | |
508 | fs->data_align = fde->cie->data_alignment_factor; | |
509 | fs->code_align = fde->cie->code_alignment_factor; | |
510 | fs->retaddr_column = fde->cie->return_address_register; | |
511 | ||
512 | /* First decode all the insns in the CIE. */ | |
513 | execute_cfa_program (fde->cie->initial_instructions, | |
514 | fde->cie->end, next_frame, fs); | |
515 | ||
516 | /* Save the initialized register set. */ | |
517 | fs->initial = fs->regs; | |
518 | fs->initial.reg = dwarf2_frame_state_copy_regs (&fs->regs); | |
519 | ||
520 | /* Then decode the insns in the FDE up to our target PC. */ | |
521 | execute_cfa_program (fde->instructions, fde->end, next_frame, fs); | |
522 | ||
523 | /* Caclulate the CFA. */ | |
524 | switch (fs->cfa_how) | |
525 | { | |
526 | case CFA_REG_OFFSET: | |
527 | cache->cfa = read_reg (next_frame, fs->cfa_reg); | |
528 | cache->cfa += fs->cfa_offset; | |
529 | break; | |
530 | ||
531 | case CFA_EXP: | |
532 | cache->cfa = | |
533 | execute_stack_op (fs->cfa_exp, fs->cfa_exp_len, next_frame, 0); | |
534 | break; | |
535 | ||
536 | default: | |
537 | internal_error (__FILE__, __LINE__, "Unknown CFA rule."); | |
538 | } | |
539 | ||
540 | /* Save the register info in the cache. */ | |
541 | for (reg = 0; reg < fs->regs.num_regs; reg++) | |
542 | { | |
543 | int regnum; | |
544 | ||
545 | /* Skip the return address column. */ | |
546 | if (reg == fs->retaddr_column) | |
a42e117c AC |
547 | /* NOTE: cagney/2003-06-07: Is this right? What if the |
548 | RETADDR_COLUM corresponds to a real register (and, worse, | |
549 | that isn't the PC_REGNUM)? I'm guessing that the PC_REGNUM | |
550 | further down is trying to handle this. That can't be right | |
551 | though - PC_REGNUM may not be valid (it can be -ve). I | |
552 | think, instead when RETADDR_COLUM isn't a real register, it | |
553 | should map itself onto frame_pc_unwind. */ | |
cfc14b3a MK |
554 | continue; |
555 | ||
556 | /* Use the GDB register number as index. */ | |
557 | regnum = DWARF2_REG_TO_REGNUM (reg); | |
558 | ||
559 | if (regnum >= 0 && regnum < num_regs) | |
560 | cache->reg[regnum] = fs->regs.reg[reg]; | |
561 | } | |
562 | ||
f3e0f90b RH |
563 | /* Store the location of the return addess. If the return address |
564 | column (adjusted) is not the same as gdb's PC_REGNUM, then this | |
565 | implies a copy from the ra column register. */ | |
566 | if (fs->retaddr_column < fs->regs.num_regs | |
567 | && fs->regs.reg[fs->retaddr_column].how != REG_UNSAVED) | |
a42e117c AC |
568 | { |
569 | /* See comment above about a possibly -ve PC_REGNUM. If this | |
570 | assertion fails, it's a problem with this code and not the | |
571 | architecture. */ | |
572 | gdb_assert (PC_REGNUM >= 0); | |
573 | cache->reg[PC_REGNUM] = fs->regs.reg[fs->retaddr_column]; | |
574 | } | |
f3e0f90b RH |
575 | else |
576 | { | |
577 | reg = DWARF2_REG_TO_REGNUM (fs->retaddr_column); | |
578 | if (reg != PC_REGNUM) | |
579 | { | |
a42e117c AC |
580 | /* See comment above about PC_REGNUM being -ve. If this |
581 | assertion fails, it's a problem with this code and not | |
582 | the architecture. */ | |
583 | gdb_assert (PC_REGNUM >= 0); | |
f3e0f90b RH |
584 | cache->reg[PC_REGNUM].loc.reg = reg; |
585 | cache->reg[PC_REGNUM].how = REG_SAVED_REG; | |
586 | } | |
587 | } | |
cfc14b3a MK |
588 | |
589 | do_cleanups (old_chain); | |
590 | ||
591 | *this_cache = cache; | |
592 | return cache; | |
593 | } | |
594 | ||
595 | static void | |
596 | dwarf2_frame_this_id (struct frame_info *next_frame, void **this_cache, | |
597 | struct frame_id *this_id) | |
598 | { | |
599 | struct dwarf2_frame_cache *cache = | |
600 | dwarf2_frame_cache (next_frame, this_cache); | |
601 | ||
602 | (*this_id) = frame_id_build (cache->cfa, frame_func_unwind (next_frame)); | |
603 | } | |
604 | ||
605 | static void | |
606 | dwarf2_frame_prev_register (struct frame_info *next_frame, void **this_cache, | |
607 | int regnum, int *optimizedp, | |
608 | enum lval_type *lvalp, CORE_ADDR *addrp, | |
609 | int *realnump, void *valuep) | |
610 | { | |
611 | struct dwarf2_frame_cache *cache = | |
612 | dwarf2_frame_cache (next_frame, this_cache); | |
613 | ||
614 | switch (cache->reg[regnum].how) | |
615 | { | |
616 | case REG_UNSAVED: | |
617 | *optimizedp = 1; | |
618 | *lvalp = not_lval; | |
619 | *addrp = 0; | |
620 | *realnump = -1; | |
621 | if (regnum == SP_REGNUM) | |
622 | { | |
623 | /* GCC defines the CFA as the value of the stack pointer | |
624 | just before the call instruction is executed. Do other | |
625 | compilers use the same definition? */ | |
a42e117c AC |
626 | /* DWARF V3 Draft 7 p102: Typically, the CFA is defined to |
627 | be the value of the stack pointer at the call site in the | |
628 | previous frame (which may be different from its value on | |
629 | entry to the current frame). */ | |
630 | /* DWARF V3 Draft 7 p103: The first column of the rules | |
631 | defines the rule which computes the CFA value; it may be | |
632 | either a register and a signed offset that are added | |
633 | together or a DWARF expression that is evaluated. */ | |
634 | /* FIXME: cagney/2003-07-07: I don't understand this. The | |
635 | CFI info should have provided unwind information for the | |
636 | SP register and then pointed ->cfa_reg at it, not the | |
637 | reverse. Assuming that SP_REGNUM is !-ve, there is a | |
638 | very real posibility that CFA is an offset from some | |
639 | other register, having nothing to do with the unwound SP | |
640 | value. */ | |
cfc14b3a MK |
641 | *optimizedp = 0; |
642 | if (valuep) | |
643 | { | |
644 | /* Store the value. */ | |
645 | store_typed_address (valuep, builtin_type_void_data_ptr, | |
646 | cache->cfa); | |
647 | } | |
648 | } | |
649 | else if (valuep) | |
650 | { | |
651 | /* In some cases, for example %eflags on the i386, we have | |
652 | to provide a sane value, even though this register wasn't | |
653 | saved. Assume we can get it from NEXT_FRAME. */ | |
654 | frame_unwind_register (next_frame, regnum, valuep); | |
655 | } | |
656 | break; | |
657 | ||
658 | case REG_SAVED_OFFSET: | |
659 | *optimizedp = 0; | |
660 | *lvalp = lval_memory; | |
661 | *addrp = cache->cfa + cache->reg[regnum].loc.offset; | |
662 | *realnump = -1; | |
663 | if (valuep) | |
664 | { | |
665 | /* Read the value in from memory. */ | |
666 | read_memory (*addrp, valuep, | |
667 | register_size (current_gdbarch, regnum)); | |
668 | } | |
669 | break; | |
670 | ||
671 | case REG_SAVED_REG: | |
672 | regnum = DWARF2_REG_TO_REGNUM (cache->reg[regnum].loc.reg); | |
673 | frame_register_unwind (next_frame, regnum, | |
674 | optimizedp, lvalp, addrp, realnump, valuep); | |
675 | break; | |
676 | ||
677 | case REG_SAVED_EXP: | |
678 | *optimizedp = 0; | |
679 | *lvalp = lval_memory; | |
680 | *addrp = execute_stack_op (cache->reg[regnum].loc.exp, | |
681 | cache->reg[regnum].exp_len, | |
682 | next_frame, cache->cfa); | |
683 | *realnump = -1; | |
684 | if (valuep) | |
685 | { | |
686 | /* Read the value in from memory. */ | |
687 | read_memory (*addrp, valuep, | |
688 | register_size (current_gdbarch, regnum)); | |
689 | } | |
690 | break; | |
691 | ||
692 | case REG_UNMODIFIED: | |
693 | frame_register_unwind (next_frame, regnum, | |
694 | optimizedp, lvalp, addrp, realnump, valuep); | |
695 | break; | |
696 | ||
697 | default: | |
698 | internal_error (__FILE__, __LINE__, "Unknown register rule."); | |
699 | } | |
700 | } | |
701 | ||
702 | static const struct frame_unwind dwarf2_frame_unwind = | |
703 | { | |
704 | NORMAL_FRAME, | |
705 | dwarf2_frame_this_id, | |
706 | dwarf2_frame_prev_register | |
707 | }; | |
708 | ||
709 | const struct frame_unwind * | |
710 | dwarf2_frame_p (CORE_ADDR pc) | |
711 | { | |
712 | /* The way GDB works, this function can be called with PC just after | |
713 | the last instruction of the function we're supposed to return the | |
714 | unwind methods for. In that case we won't find the correct FDE; | |
715 | instead we find the FDE for the next function, or we won't find | |
716 | an FDE at all. There is a possible solution (see the comment in | |
717 | dwarf2_frame_cache), GDB doesn't pass us enough information to | |
718 | implement it. */ | |
719 | if (dwarf2_frame_find_fde (&pc)) | |
720 | return &dwarf2_frame_unwind; | |
721 | ||
722 | return NULL; | |
723 | } | |
724 | \f | |
725 | ||
726 | /* There is no explicitly defined relationship between the CFA and the | |
727 | location of frame's local variables and arguments/parameters. | |
728 | Therefore, frame base methods on this page should probably only be | |
729 | used as a last resort, just to avoid printing total garbage as a | |
730 | response to the "info frame" command. */ | |
731 | ||
732 | static CORE_ADDR | |
733 | dwarf2_frame_base_address (struct frame_info *next_frame, void **this_cache) | |
734 | { | |
735 | struct dwarf2_frame_cache *cache = | |
736 | dwarf2_frame_cache (next_frame, this_cache); | |
737 | ||
738 | return cache->cfa; | |
739 | } | |
740 | ||
741 | static const struct frame_base dwarf2_frame_base = | |
742 | { | |
743 | &dwarf2_frame_unwind, | |
744 | dwarf2_frame_base_address, | |
745 | dwarf2_frame_base_address, | |
746 | dwarf2_frame_base_address | |
747 | }; | |
748 | ||
749 | const struct frame_base * | |
750 | dwarf2_frame_base_p (CORE_ADDR pc) | |
751 | { | |
752 | if (dwarf2_frame_find_fde (&pc)) | |
753 | return &dwarf2_frame_base; | |
754 | ||
755 | return NULL; | |
756 | } | |
757 | \f | |
758 | /* A minimal decoding of DWARF2 compilation units. We only decode | |
759 | what's needed to get to the call frame information. */ | |
760 | ||
761 | struct comp_unit | |
762 | { | |
763 | /* Keep the bfd convenient. */ | |
764 | bfd *abfd; | |
765 | ||
766 | struct objfile *objfile; | |
767 | ||
768 | /* Linked list of CIEs for this object. */ | |
769 | struct dwarf2_cie *cie; | |
770 | ||
771 | /* Address size for this unit - from unit header. */ | |
772 | unsigned char addr_size; | |
773 | ||
774 | /* Pointer to the .debug_frame section loaded into memory. */ | |
775 | char *dwarf_frame_buffer; | |
776 | ||
777 | /* Length of the loaded .debug_frame section. */ | |
778 | unsigned long dwarf_frame_size; | |
779 | ||
780 | /* Pointer to the .debug_frame section. */ | |
781 | asection *dwarf_frame_section; | |
0912c7f2 MK |
782 | |
783 | /* Base for DW_EH_PE_datarel encodings. */ | |
784 | bfd_vma dbase; | |
cfc14b3a MK |
785 | }; |
786 | ||
787 | static unsigned int | |
788 | read_1_byte (bfd *bfd, char *buf) | |
789 | { | |
790 | return bfd_get_8 (abfd, (bfd_byte *) buf); | |
791 | } | |
792 | ||
793 | static unsigned int | |
794 | read_4_bytes (bfd *abfd, char *buf) | |
795 | { | |
796 | return bfd_get_32 (abfd, (bfd_byte *) buf); | |
797 | } | |
798 | ||
799 | static ULONGEST | |
800 | read_8_bytes (bfd *abfd, char *buf) | |
801 | { | |
802 | return bfd_get_64 (abfd, (bfd_byte *) buf); | |
803 | } | |
804 | ||
805 | static ULONGEST | |
806 | read_unsigned_leb128 (bfd *abfd, char *buf, unsigned int *bytes_read_ptr) | |
807 | { | |
808 | ULONGEST result; | |
809 | unsigned int num_read; | |
810 | int shift; | |
811 | unsigned char byte; | |
812 | ||
813 | result = 0; | |
814 | shift = 0; | |
815 | num_read = 0; | |
816 | ||
817 | do | |
818 | { | |
819 | byte = bfd_get_8 (abfd, (bfd_byte *) buf); | |
820 | buf++; | |
821 | num_read++; | |
822 | result |= ((byte & 0x7f) << shift); | |
823 | shift += 7; | |
824 | } | |
825 | while (byte & 0x80); | |
826 | ||
827 | *bytes_read_ptr = num_read; | |
828 | ||
829 | return result; | |
830 | } | |
831 | ||
832 | static LONGEST | |
833 | read_signed_leb128 (bfd *abfd, char *buf, unsigned int *bytes_read_ptr) | |
834 | { | |
835 | LONGEST result; | |
836 | int shift; | |
837 | unsigned int num_read; | |
838 | unsigned char byte; | |
839 | ||
840 | result = 0; | |
841 | shift = 0; | |
842 | num_read = 0; | |
843 | ||
844 | do | |
845 | { | |
846 | byte = bfd_get_8 (abfd, (bfd_byte *) buf); | |
847 | buf++; | |
848 | num_read++; | |
849 | result |= ((byte & 0x7f) << shift); | |
850 | shift += 7; | |
851 | } | |
852 | while (byte & 0x80); | |
853 | ||
854 | if ((shift < 32) && (byte & 0x40)) | |
855 | result |= -(1 << shift); | |
856 | ||
857 | *bytes_read_ptr = num_read; | |
858 | ||
859 | return result; | |
860 | } | |
861 | ||
862 | static ULONGEST | |
863 | read_initial_length (bfd *abfd, char *buf, unsigned int *bytes_read_ptr) | |
864 | { | |
865 | LONGEST result; | |
866 | ||
867 | result = bfd_get_32 (abfd, (bfd_byte *) buf); | |
868 | if (result == 0xffffffff) | |
869 | { | |
870 | result = bfd_get_64 (abfd, (bfd_byte *) buf + 4); | |
871 | *bytes_read_ptr = 12; | |
872 | } | |
873 | else | |
874 | *bytes_read_ptr = 4; | |
875 | ||
876 | return result; | |
877 | } | |
878 | \f | |
879 | ||
880 | /* Pointer encoding helper functions. */ | |
881 | ||
882 | /* GCC supports exception handling based on DWARF2 CFI. However, for | |
883 | technical reasons, it encodes addresses in its FDE's in a different | |
884 | way. Several "pointer encodings" are supported. The encoding | |
885 | that's used for a particular FDE is determined by the 'R' | |
886 | augmentation in the associated CIE. The argument of this | |
887 | augmentation is a single byte. | |
888 | ||
889 | The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a | |
890 | LEB128. This is encoded in bits 0, 1 and 2. Bit 3 encodes whether | |
891 | the address is signed or unsigned. Bits 4, 5 and 6 encode how the | |
892 | address should be interpreted (absolute, relative to the current | |
893 | position in the FDE, ...). Bit 7, indicates that the address | |
894 | should be dereferenced. */ | |
895 | ||
896 | static unsigned char | |
897 | encoding_for_size (unsigned int size) | |
898 | { | |
899 | switch (size) | |
900 | { | |
901 | case 2: | |
902 | return DW_EH_PE_udata2; | |
903 | case 4: | |
904 | return DW_EH_PE_udata4; | |
905 | case 8: | |
906 | return DW_EH_PE_udata8; | |
907 | default: | |
908 | internal_error (__FILE__, __LINE__, "Unsupported address size"); | |
909 | } | |
910 | } | |
911 | ||
912 | static unsigned int | |
913 | size_of_encoded_value (unsigned char encoding) | |
914 | { | |
915 | if (encoding == DW_EH_PE_omit) | |
916 | return 0; | |
917 | ||
918 | switch (encoding & 0x07) | |
919 | { | |
920 | case DW_EH_PE_absptr: | |
921 | return TYPE_LENGTH (builtin_type_void_data_ptr); | |
922 | case DW_EH_PE_udata2: | |
923 | return 2; | |
924 | case DW_EH_PE_udata4: | |
925 | return 4; | |
926 | case DW_EH_PE_udata8: | |
927 | return 8; | |
928 | default: | |
929 | internal_error (__FILE__, __LINE__, "Invalid or unsupported encoding"); | |
930 | } | |
931 | } | |
932 | ||
933 | static CORE_ADDR | |
934 | read_encoded_value (struct comp_unit *unit, unsigned char encoding, | |
935 | char *buf, unsigned int *bytes_read_ptr) | |
936 | { | |
937 | CORE_ADDR base; | |
938 | ||
939 | /* GCC currently doesn't generate DW_EH_PE_indirect encodings for | |
940 | FDE's. */ | |
941 | if (encoding & DW_EH_PE_indirect) | |
942 | internal_error (__FILE__, __LINE__, | |
943 | "Unsupported encoding: DW_EH_PE_indirect"); | |
944 | ||
945 | switch (encoding & 0x70) | |
946 | { | |
947 | case DW_EH_PE_absptr: | |
948 | base = 0; | |
949 | break; | |
950 | case DW_EH_PE_pcrel: | |
951 | base = bfd_get_section_vma (unit->bfd, unit->dwarf_frame_section); | |
952 | base += (buf - unit->dwarf_frame_buffer); | |
953 | break; | |
0912c7f2 MK |
954 | case DW_EH_PE_datarel: |
955 | base = unit->dbase; | |
956 | break; | |
cfc14b3a MK |
957 | default: |
958 | internal_error (__FILE__, __LINE__, "Invalid or unsupported encoding"); | |
959 | } | |
960 | ||
961 | if ((encoding & 0x0f) == 0x00) | |
962 | encoding |= encoding_for_size (TYPE_LENGTH(builtin_type_void_data_ptr)); | |
963 | ||
964 | switch (encoding & 0x0f) | |
965 | { | |
966 | case DW_EH_PE_udata2: | |
967 | *bytes_read_ptr = 2; | |
968 | return (base + bfd_get_16 (unit->abfd, (bfd_byte *) buf)); | |
969 | case DW_EH_PE_udata4: | |
970 | *bytes_read_ptr = 4; | |
971 | return (base + bfd_get_32 (unit->abfd, (bfd_byte *) buf)); | |
972 | case DW_EH_PE_udata8: | |
973 | *bytes_read_ptr = 8; | |
974 | return (base + bfd_get_64 (unit->abfd, (bfd_byte *) buf)); | |
975 | case DW_EH_PE_sdata2: | |
976 | *bytes_read_ptr = 2; | |
977 | return (base + bfd_get_signed_16 (unit->abfd, (bfd_byte *) buf)); | |
978 | case DW_EH_PE_sdata4: | |
979 | *bytes_read_ptr = 4; | |
980 | return (base + bfd_get_signed_32 (unit->abfd, (bfd_byte *) buf)); | |
981 | case DW_EH_PE_sdata8: | |
982 | *bytes_read_ptr = 8; | |
983 | return (base + bfd_get_signed_64 (unit->abfd, (bfd_byte *) buf)); | |
984 | default: | |
985 | internal_error (__FILE__, __LINE__, "Invalid or unsupported encoding"); | |
986 | } | |
987 | } | |
988 | \f | |
989 | ||
990 | /* GCC uses a single CIE for all FDEs in a .debug_frame section. | |
991 | That's why we use a simple linked list here. */ | |
992 | ||
993 | static struct dwarf2_cie * | |
994 | find_cie (struct comp_unit *unit, ULONGEST cie_pointer) | |
995 | { | |
996 | struct dwarf2_cie *cie = unit->cie; | |
997 | ||
998 | while (cie) | |
999 | { | |
1000 | if (cie->cie_pointer == cie_pointer) | |
1001 | return cie; | |
1002 | ||
1003 | cie = cie->next; | |
1004 | } | |
1005 | ||
1006 | return NULL; | |
1007 | } | |
1008 | ||
1009 | static void | |
1010 | add_cie (struct comp_unit *unit, struct dwarf2_cie *cie) | |
1011 | { | |
1012 | cie->next = unit->cie; | |
1013 | unit->cie = cie; | |
1014 | } | |
1015 | ||
1016 | /* Find the FDE for *PC. Return a pointer to the FDE, and store the | |
1017 | inital location associated with it into *PC. */ | |
1018 | ||
1019 | static struct dwarf2_fde * | |
1020 | dwarf2_frame_find_fde (CORE_ADDR *pc) | |
1021 | { | |
1022 | struct objfile *objfile; | |
1023 | ||
1024 | ALL_OBJFILES (objfile) | |
1025 | { | |
1026 | struct dwarf2_fde *fde; | |
1027 | CORE_ADDR offset; | |
1028 | ||
1029 | offset = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile)); | |
1030 | ||
1031 | fde = objfile->sym_private; | |
1032 | while (fde) | |
1033 | { | |
1034 | if (*pc >= fde->initial_location + offset | |
1035 | && *pc < fde->initial_location + offset + fde->address_range) | |
1036 | { | |
1037 | *pc = fde->initial_location + offset; | |
1038 | return fde; | |
1039 | } | |
1040 | ||
1041 | fde = fde->next; | |
1042 | } | |
1043 | } | |
1044 | ||
1045 | return NULL; | |
1046 | } | |
1047 | ||
1048 | static void | |
1049 | add_fde (struct comp_unit *unit, struct dwarf2_fde *fde) | |
1050 | { | |
1051 | fde->next = unit->objfile->sym_private; | |
1052 | unit->objfile->sym_private = fde; | |
1053 | } | |
1054 | ||
1055 | #ifdef CC_HAS_LONG_LONG | |
1056 | #define DW64_CIE_ID 0xffffffffffffffffULL | |
1057 | #else | |
1058 | #define DW64_CIE_ID ~0 | |
1059 | #endif | |
1060 | ||
1061 | /* Read a CIE or FDE in BUF and decode it. */ | |
1062 | ||
1063 | static char * | |
1064 | decode_frame_entry (struct comp_unit *unit, char *buf, int eh_frame_p) | |
1065 | { | |
1066 | LONGEST length; | |
1067 | unsigned int bytes_read; | |
1068 | int dwarf64_p = 0; | |
1069 | ULONGEST cie_id = DW_CIE_ID; | |
1070 | ULONGEST cie_pointer; | |
1071 | char *start = buf; | |
1072 | char *end; | |
1073 | ||
1074 | length = read_initial_length (unit->abfd, buf, &bytes_read); | |
1075 | buf += bytes_read; | |
1076 | end = buf + length; | |
1077 | ||
1078 | if (length == 0) | |
1079 | return end; | |
1080 | ||
1081 | if (bytes_read == 12) | |
1082 | dwarf64_p = 1; | |
1083 | ||
1084 | /* In a .eh_frame section, zero is used to distinguish CIEs from | |
1085 | FDEs. */ | |
1086 | if (eh_frame_p) | |
1087 | cie_id = 0; | |
1088 | else if (dwarf64_p) | |
1089 | cie_id = DW64_CIE_ID; | |
1090 | ||
1091 | if (dwarf64_p) | |
1092 | { | |
1093 | cie_pointer = read_8_bytes (unit->abfd, buf); | |
1094 | buf += 8; | |
1095 | } | |
1096 | else | |
1097 | { | |
1098 | cie_pointer = read_4_bytes (unit->abfd, buf); | |
1099 | buf += 4; | |
1100 | } | |
1101 | ||
1102 | if (cie_pointer == cie_id) | |
1103 | { | |
1104 | /* This is a CIE. */ | |
1105 | struct dwarf2_cie *cie; | |
1106 | char *augmentation; | |
1107 | ||
1108 | /* Record the offset into the .debug_frame section of this CIE. */ | |
1109 | cie_pointer = start - unit->dwarf_frame_buffer; | |
1110 | ||
1111 | /* Check whether we've already read it. */ | |
1112 | if (find_cie (unit, cie_pointer)) | |
1113 | return end; | |
1114 | ||
1115 | cie = (struct dwarf2_cie *) | |
1116 | obstack_alloc (&unit->objfile->psymbol_obstack, | |
1117 | sizeof (struct dwarf2_cie)); | |
1118 | cie->initial_instructions = NULL; | |
1119 | cie->cie_pointer = cie_pointer; | |
1120 | ||
1121 | /* The encoding for FDE's in a normal .debug_frame section | |
1122 | depends on the target address size as specified in the | |
1123 | Compilation Unit Header. */ | |
1124 | cie->encoding = encoding_for_size (unit->addr_size); | |
1125 | ||
1126 | /* Check version number. */ | |
1127 | gdb_assert (read_1_byte (unit->abfd, buf) == DW_CIE_VERSION); | |
1128 | buf += 1; | |
1129 | ||
1130 | /* Interpret the interesting bits of the augmentation. */ | |
1131 | augmentation = buf; | |
1132 | buf = augmentation + strlen (augmentation) + 1; | |
1133 | ||
1134 | /* The GCC 2.x "eh" augmentation has a pointer immediately | |
1135 | following the augmentation string, so it must be handled | |
1136 | first. */ | |
1137 | if (augmentation[0] == 'e' && augmentation[1] == 'h') | |
1138 | { | |
1139 | /* Skip. */ | |
1140 | buf += TYPE_LENGTH (builtin_type_void_data_ptr); | |
1141 | augmentation += 2; | |
1142 | } | |
1143 | ||
1144 | cie->code_alignment_factor = | |
1145 | read_unsigned_leb128 (unit->abfd, buf, &bytes_read); | |
1146 | buf += bytes_read; | |
1147 | ||
1148 | cie->data_alignment_factor = | |
1149 | read_signed_leb128 (unit->abfd, buf, &bytes_read); | |
1150 | buf += bytes_read; | |
1151 | ||
1152 | cie->return_address_register = read_1_byte (unit->abfd, buf); | |
1153 | buf += 1; | |
1154 | ||
7131cb6e RH |
1155 | cie->saw_z_augmentation = (*augmentation == 'z'); |
1156 | if (cie->saw_z_augmentation) | |
cfc14b3a MK |
1157 | { |
1158 | ULONGEST length; | |
1159 | ||
1160 | length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read); | |
1161 | buf += bytes_read; | |
1162 | cie->initial_instructions = buf + length; | |
1163 | augmentation++; | |
1164 | } | |
1165 | ||
1166 | while (*augmentation) | |
1167 | { | |
1168 | /* "L" indicates a byte showing how the LSDA pointer is encoded. */ | |
1169 | if (*augmentation == 'L') | |
1170 | { | |
1171 | /* Skip. */ | |
1172 | buf++; | |
1173 | augmentation++; | |
1174 | } | |
1175 | ||
1176 | /* "R" indicates a byte indicating how FDE addresses are encoded. */ | |
1177 | else if (*augmentation == 'R') | |
1178 | { | |
1179 | cie->encoding = *buf++; | |
1180 | augmentation++; | |
1181 | } | |
1182 | ||
1183 | /* "P" indicates a personality routine in the CIE augmentation. */ | |
1184 | else if (*augmentation == 'P') | |
1185 | { | |
1186 | /* Skip. */ | |
1187 | buf += size_of_encoded_value (*buf++); | |
1188 | augmentation++; | |
1189 | } | |
1190 | ||
1191 | /* Otherwise we have an unknown augmentation. | |
1192 | Bail out unless we saw a 'z' prefix. */ | |
1193 | else | |
1194 | { | |
1195 | if (cie->initial_instructions == NULL) | |
1196 | return end; | |
1197 | ||
1198 | /* Skip unknown augmentations. */ | |
1199 | buf = cie->initial_instructions; | |
1200 | break; | |
1201 | } | |
1202 | } | |
1203 | ||
1204 | cie->initial_instructions = buf; | |
1205 | cie->end = end; | |
1206 | ||
1207 | add_cie (unit, cie); | |
1208 | } | |
1209 | else | |
1210 | { | |
1211 | /* This is a FDE. */ | |
1212 | struct dwarf2_fde *fde; | |
1213 | ||
1214 | if (eh_frame_p) | |
1215 | { | |
1216 | /* In an .eh_frame section, the CIE pointer is the delta | |
1217 | between the address within the FDE where the CIE pointer | |
1218 | is stored and the address of the CIE. Convert it to an | |
1219 | offset into the .eh_frame section. */ | |
1220 | cie_pointer = buf - unit->dwarf_frame_buffer - cie_pointer; | |
1221 | cie_pointer -= (dwarf64_p ? 8 : 4); | |
1222 | } | |
1223 | ||
1224 | fde = (struct dwarf2_fde *) | |
1225 | obstack_alloc (&unit->objfile->psymbol_obstack, | |
1226 | sizeof (struct dwarf2_fde)); | |
1227 | fde->cie = find_cie (unit, cie_pointer); | |
1228 | if (fde->cie == NULL) | |
1229 | { | |
1230 | decode_frame_entry (unit, unit->dwarf_frame_buffer + cie_pointer, | |
1231 | eh_frame_p); | |
1232 | fde->cie = find_cie (unit, cie_pointer); | |
1233 | } | |
1234 | ||
1235 | gdb_assert (fde->cie != NULL); | |
1236 | ||
1237 | fde->initial_location = | |
1238 | read_encoded_value (unit, fde->cie->encoding, buf, &bytes_read); | |
1239 | buf += bytes_read; | |
1240 | ||
1241 | fde->address_range = | |
1242 | read_encoded_value (unit, fde->cie->encoding & 0x0f, buf, &bytes_read); | |
1243 | buf += bytes_read; | |
1244 | ||
7131cb6e RH |
1245 | /* A 'z' augmentation in the CIE implies the presence of an |
1246 | augmentation field in the FDE as well. The only thing known | |
1247 | to be in here at present is the LSDA entry for EH. So we | |
1248 | can skip the whole thing. */ | |
1249 | if (fde->cie->saw_z_augmentation) | |
1250 | { | |
1251 | ULONGEST length; | |
1252 | ||
1253 | length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read); | |
1254 | buf += bytes_read + length; | |
1255 | } | |
1256 | ||
cfc14b3a MK |
1257 | fde->instructions = buf; |
1258 | fde->end = end; | |
1259 | ||
1260 | add_fde (unit, fde); | |
1261 | } | |
1262 | ||
1263 | return end; | |
1264 | } | |
1265 | \f | |
1266 | ||
1267 | /* FIXME: kettenis/20030504: This still needs to be integrated with | |
1268 | dwarf2read.c in a better way. */ | |
1269 | ||
1270 | /* Imported from dwarf2read.c. */ | |
1271 | extern file_ptr dwarf_frame_offset; | |
1272 | extern unsigned int dwarf_frame_size; | |
1273 | extern asection *dwarf_frame_section; | |
1274 | extern file_ptr dwarf_eh_frame_offset; | |
1275 | extern unsigned int dwarf_eh_frame_size; | |
1276 | extern asection *dwarf_eh_frame_section; | |
1277 | ||
1278 | /* Imported from dwarf2read.c. */ | |
1279 | extern char *dwarf2_read_section (struct objfile *objfile, file_ptr offset, | |
1280 | unsigned int size, asection *sectp); | |
1281 | ||
1282 | void | |
1283 | dwarf2_build_frame_info (struct objfile *objfile) | |
1284 | { | |
1285 | struct comp_unit unit; | |
1286 | char *frame_ptr; | |
1287 | ||
1288 | /* Build a minimal decoding of the DWARF2 compilation unit. */ | |
1289 | unit.abfd = objfile->obfd; | |
1290 | unit.objfile = objfile; | |
1291 | unit.addr_size = objfile->obfd->arch_info->bits_per_address / 8; | |
0912c7f2 | 1292 | unit.dbase = 0; |
cfc14b3a MK |
1293 | |
1294 | /* First add the information from the .eh_frame section. That way, | |
1295 | the FDEs from that section are searched last. */ | |
1296 | if (dwarf_eh_frame_offset) | |
1297 | { | |
0912c7f2 MK |
1298 | asection *got; |
1299 | ||
cfc14b3a MK |
1300 | unit.cie = NULL; |
1301 | unit.dwarf_frame_buffer = dwarf2_read_section (objfile, | |
1302 | dwarf_eh_frame_offset, | |
1303 | dwarf_eh_frame_size, | |
1304 | dwarf_eh_frame_section); | |
1305 | ||
1306 | unit.dwarf_frame_size = dwarf_eh_frame_size; | |
1307 | unit.dwarf_frame_section = dwarf_eh_frame_section; | |
1308 | ||
0912c7f2 MK |
1309 | /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base |
1310 | that for the i386/amd64 target, which currently is the only | |
1311 | target in GCC that supports/uses the DW_EH_PE_datarel | |
1312 | encoding. */ | |
1313 | got = bfd_get_section_by_name (unit.abfd, ".got"); | |
1314 | if (got) | |
1315 | unit.dbase = got->vma; | |
1316 | ||
cfc14b3a MK |
1317 | frame_ptr = unit.dwarf_frame_buffer; |
1318 | while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size) | |
1319 | frame_ptr = decode_frame_entry (&unit, frame_ptr, 1); | |
1320 | } | |
1321 | ||
1322 | if (dwarf_frame_offset) | |
1323 | { | |
1324 | unit.cie = NULL; | |
1325 | unit.dwarf_frame_buffer = dwarf2_read_section (objfile, | |
1326 | dwarf_frame_offset, | |
1327 | dwarf_frame_size, | |
1328 | dwarf_frame_section); | |
1329 | unit.dwarf_frame_size = dwarf_frame_size; | |
1330 | unit.dwarf_frame_section = dwarf_frame_section; | |
1331 | ||
1332 | frame_ptr = unit.dwarf_frame_buffer; | |
1333 | while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size) | |
1334 | frame_ptr = decode_frame_entry (&unit, frame_ptr, 0); | |
1335 | } | |
1336 | } |