Branch data Line data Source code
1 : : /* CFI program execution.
2 : : Copyright (C) 2009-2010, 2014, 2015 Red Hat, Inc.
3 : : This file is part of elfutils.
4 : :
5 : : This file is free software; you can redistribute it and/or modify
6 : : it under the terms of either
7 : :
8 : : * the GNU Lesser General Public License as published by the Free
9 : : Software Foundation; either version 3 of the License, or (at
10 : : your option) any later version
11 : :
12 : : or
13 : :
14 : : * the GNU General Public License as published by the Free
15 : : Software Foundation; either version 2 of the License, or (at
16 : : your option) any later version
17 : :
18 : : or both in parallel, as here.
19 : :
20 : : elfutils is distributed in the hope that it will be useful, but
21 : : WITHOUT ANY WARRANTY; without even the implied warranty of
22 : : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 : : General Public License for more details.
24 : :
25 : : You should have received copies of the GNU General Public License and
26 : : the GNU Lesser General Public License along with this program. If
27 : : not, see <http://www.gnu.org/licenses/>. */
28 : :
29 : : #ifdef HAVE_CONFIG_H
30 : : # include <config.h>
31 : : #endif
32 : :
33 : : #include <dwarf.h>
34 : : #include "libebl.h"
35 : : #include "cfi.h"
36 : : #include "memory-access.h"
37 : : #include "encoded-value.h"
38 : : #include "system.h"
39 : : #include <assert.h>
40 : : #include <stdlib.h>
41 : : #include <string.h>
42 : :
43 : : #define CFI_PRIMARY_MAX 0x3f
44 : :
45 : : static Dwarf_Frame *
46 : 13540 : duplicate_frame_state (const Dwarf_Frame *original,
47 : : Dwarf_Frame *prev)
48 : : {
49 : 13540 : size_t size = offsetof (Dwarf_Frame, regs[original->nregs]);
50 : 13540 : Dwarf_Frame *copy = malloc (size);
51 [ + - ]: 13540 : if (likely (copy != NULL))
52 : : {
53 : 13540 : memcpy (copy, original, size);
54 : 13540 : copy->prev = prev;
55 : : }
56 : 13540 : return copy;
57 : : }
58 : :
59 : : static inline bool
60 : 3540 : enough_registers (Dwarf_Word reg, Dwarf_Frame **pfs, int *result)
61 : : {
62 : : /* Don't allow insanely large register numbers. 268435456 registers
63 : : should be enough for anybody. And very large values might overflow
64 : : the array size and offsetof calculations below. */
65 [ - + ]: 3540 : if (unlikely (reg >= INT32_MAX / sizeof ((*pfs)->regs[0])))
66 : : {
67 : 0 : *result = DWARF_E_INVALID_CFI;
68 : 0 : return false;
69 : : }
70 : :
71 [ + + ]: 3540 : if ((*pfs)->nregs <= reg)
72 : : {
73 : 1958 : size_t size = offsetof (Dwarf_Frame, regs[reg + 1]);
74 : 1958 : Dwarf_Frame *bigger = realloc (*pfs, size);
75 [ - + ]: 1958 : if (unlikely (bigger == NULL))
76 : : {
77 : 0 : *result = DWARF_E_NOMEM;
78 : 0 : return false;
79 : : }
80 : : else
81 : : {
82 : 1958 : eu_static_assert (reg_unspecified == 0);
83 : 1958 : memset (bigger->regs + bigger->nregs, 0,
84 : 1958 : (reg + 1 - bigger->nregs) * sizeof bigger->regs[0]);
85 : 1958 : bigger->nregs = reg + 1;
86 : 1958 : *pfs = bigger;
87 : : }
88 : : }
89 : : return true;
90 : : }
91 : :
92 : : static inline void
93 : 708 : require_cfa_offset (Dwarf_Frame *fs)
94 : : {
95 : 708 : if (unlikely (fs->cfa_rule != cfa_offset))
96 : 0 : fs->cfa_rule = cfa_invalid;
97 : : }
98 : :
99 : : /* Returns a DWARF_E_* error code, usually NOERROR or INVALID_CFI.
100 : : Frees *STATE on failure. */
101 : : static int
102 : 13884 : execute_cfi (Dwarf_CFI *cache,
103 : : const struct dwarf_cie *cie,
104 : : Dwarf_Frame **state,
105 : : const uint8_t *program, const uint8_t *const end, bool abi_cfi,
106 : : Dwarf_Addr loc, Dwarf_Addr find_pc)
107 : : {
108 : : /* The caller should not give us anything out of range. */
109 [ - + ]: 13884 : assert (loc <= find_pc);
110 : :
111 : 13884 : int result = DWARF_E_NOERROR;
112 : :
113 : : #define cfi_assert(ok) do { \
114 : : if (likely (ok)) break; \
115 : : result = DWARF_E_INVALID_CFI; \
116 : : goto out; \
117 : : } while (0)
118 : :
119 : 13884 : Dwarf_Frame *fs = *state;
120 : :
121 : : #define register_rule(regno, r_rule, r_value) do { \
122 : : if (unlikely (! enough_registers (regno, &fs, &result))) \
123 : : goto out; \
124 : : fs->regs[regno].rule = reg_##r_rule; \
125 : : fs->regs[regno].value = (r_value); \
126 : : } while (0)
127 : :
128 [ + + ]: 34524 : while (program < end)
129 : : {
130 : 29352 : uint8_t opcode = *program++;
131 : 29352 : Dwarf_Word regno;
132 : 29352 : Dwarf_Word offset;
133 : 29352 : Dwarf_Word sf_offset;
134 : 29352 : Dwarf_Word operand = opcode & CFI_PRIMARY_MAX;
135 [ + + + - : 29352 : switch (opcode)
- - + + -
+ - + + +
- + + - +
- + + - -
+ + + + +
- - ]
136 : : {
137 : : /* These cases move LOC, i.e. "create a new table row". */
138 : :
139 : 244 : case DW_CFA_advance_loc1:
140 : 244 : operand = *program++;
141 : 9566 : FALLTHROUGH;
142 : : case DW_CFA_advance_loc + 0 ... DW_CFA_advance_loc + CFI_PRIMARY_MAX:
143 : 9566 : advance_loc:
144 : 9566 : loc += operand * cie->code_alignment_factor;
145 : 9566 : break;
146 : :
147 : 28 : case DW_CFA_advance_loc2:
148 [ - + ]: 28 : cfi_assert (program + 2 <= end);
149 [ + + ]: 28 : operand = read_2ubyte_unaligned_inc (cache, program);
150 : 28 : goto advance_loc;
151 : 0 : case DW_CFA_advance_loc4:
152 [ # # ]: 0 : cfi_assert (program + 4 <= end);
153 [ # # ]: 0 : operand = read_4ubyte_unaligned_inc (cache, program);
154 : 0 : goto advance_loc;
155 : 0 : case DW_CFA_MIPS_advance_loc8:
156 [ # # ]: 0 : cfi_assert (program + 8 <= end);
157 [ # # ]: 0 : operand = read_8ubyte_unaligned_inc (cache, program);
158 : 0 : goto advance_loc;
159 : :
160 : 0 : case DW_CFA_set_loc:
161 [ # # ]: 0 : if (likely (!read_encoded_value (cache, cie->fde_encoding,
162 : : &program, &loc)))
163 : : break;
164 : 0 : result = INTUSE(dwarf_errno) ();
165 : 0 : goto out;
166 : :
167 : : /* Now all following cases affect this row, but do not touch LOC.
168 : : These cases end with 'continue'. We only get out of the
169 : : switch block for the row-copying (LOC-moving) cases above. */
170 : :
171 : 218 : case DW_CFA_def_cfa:
172 : 218 : get_uleb128 (operand, program, end);
173 [ - + ]: 218 : cfi_assert (program < end);
174 : 218 : get_uleb128 (offset, program, end);
175 : 218 : def_cfa:
176 : 218 : fs->cfa_rule = cfa_offset;
177 : 218 : fs->cfa_val_reg = operand;
178 : 218 : fs->cfa_val_offset = offset;
179 : : /* Prime the rest of the Dwarf_Op so dwarf_frame_cfa can use it. */
180 : 218 : fs->cfa_data.offset.atom = DW_OP_bregx;
181 : 218 : fs->cfa_data.offset.offset = 0;
182 : 218 : continue;
183 : :
184 : 120 : case DW_CFA_def_cfa_register:
185 : 120 : get_uleb128 (regno, program, end);
186 [ - + ]: 120 : require_cfa_offset (fs);
187 : 120 : fs->cfa_val_reg = regno;
188 : 120 : continue;
189 : :
190 : 0 : case DW_CFA_def_cfa_sf:
191 : 0 : get_uleb128 (operand, program, end);
192 [ # # ]: 0 : cfi_assert (program < end);
193 : 0 : get_sleb128 (sf_offset, program, end);
194 : 0 : offset = sf_offset * cie->data_alignment_factor;
195 : 0 : goto def_cfa;
196 : :
197 : 588 : case DW_CFA_def_cfa_offset:
198 : 588 : get_uleb128 (offset, program, end);
199 : 588 : def_cfa_offset:
200 [ - + ]: 588 : require_cfa_offset (fs);
201 : 588 : fs->cfa_val_offset = offset;
202 : 588 : continue;
203 : :
204 : 0 : case DW_CFA_def_cfa_offset_sf:
205 : 0 : get_sleb128 (sf_offset, program, end);
206 : 0 : offset = sf_offset * cie->data_alignment_factor;
207 : 0 : goto def_cfa_offset;
208 : :
209 : 2 : case DW_CFA_def_cfa_expression:
210 : : /* DW_FORM_block is a ULEB128 length followed by that many bytes. */
211 : 2 : get_uleb128 (operand, program, end);
212 [ - + ]: 2 : cfi_assert (operand <= (Dwarf_Word) (end - program));
213 : 2 : fs->cfa_rule = cfa_expr;
214 : 2 : fs->cfa_data.expr.data = (unsigned char *) program;
215 : 2 : fs->cfa_data.expr.length = operand;
216 : 2 : program += operand;
217 : 2 : continue;
218 : :
219 : 22 : case DW_CFA_undefined:
220 : 22 : get_uleb128 (regno, program, end);
221 [ - + ]: 22 : register_rule (regno, undefined, 0);
222 : 22 : continue;
223 : :
224 : 2348 : case DW_CFA_same_value:
225 : 2348 : get_uleb128 (regno, program, end);
226 [ - + ]: 2348 : register_rule (regno, same_value, 0);
227 : 2348 : continue;
228 : :
229 : 0 : case DW_CFA_offset_extended:
230 : 0 : get_uleb128 (operand, program, end);
231 [ # # ]: 0 : cfi_assert (program < end);
232 : 846 : FALLTHROUGH;
233 : : case DW_CFA_offset + 0 ... DW_CFA_offset + CFI_PRIMARY_MAX:
234 : 846 : get_uleb128 (offset, program, end);
235 : 846 : offset *= cie->data_alignment_factor;
236 : 868 : offset_extended:
237 [ - + ]: 868 : register_rule (operand, offset, offset);
238 : 868 : continue;
239 : :
240 : 22 : case DW_CFA_offset_extended_sf:
241 : 22 : get_uleb128 (operand, program, end);
242 [ - + ]: 22 : cfi_assert (program < end);
243 : 22 : get_sleb128 (sf_offset, program, end);
244 : 22 : offset_extended_sf:
245 : 22 : offset = sf_offset * cie->data_alignment_factor;
246 : 22 : goto offset_extended;
247 : :
248 : 0 : case DW_CFA_GNU_negative_offset_extended:
249 : : /* GNU extension obsoleted by DW_CFA_offset_extended_sf. */
250 : 0 : get_uleb128 (operand, program, end);
251 [ # # ]: 0 : cfi_assert (program < end);
252 : 0 : get_uleb128 (offset, program, end);
253 : 0 : sf_offset = -offset;
254 : 0 : goto offset_extended_sf;
255 : :
256 : 176 : case DW_CFA_val_offset:
257 : 176 : get_uleb128 (operand, program, end);
258 [ - + ]: 176 : cfi_assert (program < end);
259 : 176 : get_uleb128 (offset, program, end);
260 : 176 : offset *= cie->data_alignment_factor;
261 : 176 : val_offset:
262 [ - + ]: 176 : register_rule (operand, val_offset, offset);
263 : 176 : continue;
264 : :
265 : 0 : case DW_CFA_val_offset_sf:
266 : 0 : get_uleb128 (operand, program, end);
267 [ # # ]: 0 : cfi_assert (program < end);
268 : 0 : get_sleb128 (sf_offset, program, end);
269 : 0 : offset = sf_offset * cie->data_alignment_factor;
270 : 0 : goto val_offset;
271 : :
272 : 26 : case DW_CFA_register:
273 : 26 : get_uleb128 (regno, program, end);
274 [ - + ]: 26 : cfi_assert (program < end);
275 : 26 : get_uleb128 (operand, program, end);
276 [ - + ]: 26 : register_rule (regno, register, operand);
277 : 26 : continue;
278 : :
279 : 10 : case DW_CFA_expression:
280 : : /* Expression rule relies on section data, abi_cfi cannot use it. */
281 [ - + ]: 10 : assert (! abi_cfi);
282 : 10 : get_uleb128 (regno, program, end);
283 : 10 : offset = program - (const uint8_t *) cache->data->d.d_buf;
284 : : /* DW_FORM_block is a ULEB128 length followed by that many bytes. */
285 [ - + ]: 10 : cfi_assert (program < end);
286 : 10 : get_uleb128 (operand, program, end);
287 [ - + ]: 10 : cfi_assert (operand <= (Dwarf_Word) (end - program));
288 : 10 : program += operand;
289 [ - + ]: 10 : register_rule (regno, expression, offset);
290 : 10 : continue;
291 : :
292 : 0 : case DW_CFA_val_expression:
293 : : /* Expression rule relies on section data, abi_cfi cannot use it. */
294 [ # # ]: 0 : assert (! abi_cfi);
295 : 0 : get_uleb128 (regno, program, end);
296 : : /* DW_FORM_block is a ULEB128 length followed by that many bytes. */
297 : 0 : offset = program - (const uint8_t *) cache->data->d.d_buf;
298 [ # # ]: 0 : cfi_assert (program < end);
299 : 0 : get_uleb128 (operand, program, end);
300 [ # # ]: 0 : cfi_assert (operand <= (Dwarf_Word) (end - program));
301 : 0 : program += operand;
302 [ # # ]: 0 : register_rule (regno, val_expression, offset);
303 : 0 : continue;
304 : :
305 : 0 : case DW_CFA_restore_extended:
306 : 0 : get_uleb128 (operand, program, end);
307 : 72 : FALLTHROUGH;
308 : 72 : case DW_CFA_restore + 0 ... DW_CFA_restore + CFI_PRIMARY_MAX:
309 : :
310 [ - + - - ]: 72 : if (unlikely (abi_cfi) && likely (opcode == DW_CFA_restore))
311 : : {
312 : : /* Special case hack to give backend abi_cfi a shorthand. */
313 : 0 : cache->default_same_value = true;
314 : 0 : continue;
315 : : }
316 : :
317 : : /* This can't be used in the CIE's own initial instructions. */
318 [ - + ]: 72 : cfi_assert (cie->initial_state != NULL);
319 : :
320 : : /* Restore the CIE's initial rule for this register. */
321 [ - + ]: 72 : if (unlikely (! enough_registers (operand, &fs, &result)))
322 : 0 : goto out;
323 [ + - ]: 72 : if (cie->initial_state->nregs > operand)
324 : 72 : fs->regs[operand] = cie->initial_state->regs[operand];
325 : : else
326 : 0 : fs->regs[operand].rule = reg_unspecified;
327 : 72 : continue;
328 : :
329 : 32 : case DW_CFA_remember_state:
330 : 32 : {
331 : : /* Duplicate the state and chain the copy on. */
332 : 32 : Dwarf_Frame *copy = duplicate_frame_state (fs, fs);
333 [ - + ]: 32 : if (unlikely (copy == NULL))
334 : : {
335 : 0 : result = DWARF_E_NOMEM;
336 : 0 : goto out;
337 : : }
338 : 32 : fs = copy;
339 : 32 : continue;
340 : : }
341 : :
342 : 32 : case DW_CFA_restore_state:
343 : 32 : {
344 : : /* Pop the current state off and use the old one instead. */
345 : 32 : Dwarf_Frame *prev = fs->prev;
346 [ - + ]: 32 : cfi_assert (prev != NULL);
347 : 32 : free (fs);
348 : 32 : fs = prev;
349 : 32 : continue;
350 : : }
351 : :
352 : 15254 : case DW_CFA_nop:
353 : 15254 : continue;
354 : :
355 : 18 : case DW_CFA_GNU_window_save: /* DW_CFA_AARCH64_negate_ra_state */
356 [ + - ]: 18 : if (cache->e_machine == EM_AARCH64)
357 : : {
358 : : /* Toggles the return address state, indicating whether
359 : : the return address is encrypted or not on
360 : : aarch64. XXX not handled yet. */
361 : : }
362 : : else
363 : : {
364 : : /* This is magic shorthand used only by SPARC. It's
365 : : equivalent to a bunch of DW_CFA_register and
366 : : DW_CFA_offset operations. */
367 [ - + ]: 18 : if (unlikely (! enough_registers (31, &fs, &result)))
368 : 0 : goto out;
369 [ + + ]: 162 : for (regno = 8; regno < 16; ++regno)
370 : : {
371 : : /* Find each %oN in %iN. */
372 : 144 : fs->regs[regno].rule = reg_register;
373 : 144 : fs->regs[regno].value = regno + 16;
374 : : }
375 : 18 : unsigned int address_size;
376 : 36 : address_size = (cache->e_ident[EI_CLASS] == ELFCLASS32
377 [ + - ]: 18 : ? 4 : 8);
378 [ + + ]: 306 : for (; regno < 32; ++regno)
379 : : {
380 : : /* Find %l0..%l7 and %i0..%i7 in a block at the CFA. */
381 : 288 : fs->regs[regno].rule = reg_offset;
382 : 288 : fs->regs[regno].value = (regno - 16) * address_size;
383 : : }
384 : : }
385 : 18 : continue;
386 : :
387 : 0 : case DW_CFA_GNU_args_size:
388 : : /* XXX is this useful for anything? */
389 : 0 : get_uleb128 (operand, program, end);
390 : 0 : continue;
391 : :
392 : : default:
393 : 0 : cfi_assert (false);
394 : : continue;
395 : : }
396 : :
397 : : /* We get here only for the cases that have just moved LOC. */
398 [ - + ]: 9566 : cfi_assert (cie->initial_state != NULL);
399 [ + + ]: 9566 : if (find_pc >= loc)
400 : : /* This advance has not yet reached FIND_PC. */
401 : 854 : fs->start = loc;
402 : : else
403 : : {
404 : : /* We have just advanced past the address we're looking for.
405 : : The state currently described is what we want to see. */
406 : 8712 : fs->end = loc;
407 : 8712 : break;
408 : : }
409 : : }
410 : :
411 : : /* "The end of the instruction stream can be thought of as a
412 : : DW_CFA_set_loc (initial_location + address_range) instruction."
413 : : (DWARF 3.0 Section 6.4.3)
414 : :
415 : : When we fall off the end of the program without an advance_loc/set_loc
416 : : that put us past FIND_PC, the final state left by the FDE program
417 : : applies to this address (the caller ensured it was inside the FDE).
418 : : This address (FDE->end) is already in FS->end as set by the caller. */
419 : :
420 : : #undef register_rule
421 : : #undef cfi_assert
422 : :
423 : 5172 : out:
424 : :
425 : : /* Pop any remembered states left on the stack. */
426 [ - + ]: 13884 : while (fs->prev != NULL)
427 : : {
428 : 0 : Dwarf_Frame *prev = fs->prev;
429 : 0 : fs->prev = prev->prev;
430 : 0 : free (prev);
431 : : }
432 : :
433 [ + - ]: 13884 : if (likely (result == DWARF_E_NOERROR))
434 : 13884 : *state = fs;
435 : : else
436 : 0 : free (fs);
437 : :
438 : 13884 : return result;
439 : : }
440 : :
441 : : static int
442 : 13508 : cie_cache_initial_state (Dwarf_CFI *cache, struct dwarf_cie *cie)
443 : : {
444 : 13508 : int result = DWARF_E_NOERROR;
445 : :
446 [ + + ]: 13508 : if (likely (cie->initial_state != NULL))
447 : : return result;
448 : :
449 : : /* This CIE has not been used before. Play out its initial
450 : : instructions and cache the initial state that results.
451 : : First we'll let the backend fill in the default initial
452 : : state for this machine's ABI. */
453 : :
454 : 188 : Dwarf_CIE abi_info = { DW_CIE_ID_64, NULL, NULL, 1, 1, -1, "", NULL, 0, 0 };
455 : :
456 : : /* Make sure we have a backend handle cached. */
457 [ + + ]: 188 : if (unlikely (cache->ebl == NULL))
458 : : {
459 : 12 : cache->ebl = ebl_openbackend (cache->data->s->elf);
460 [ - + ]: 12 : if (unlikely (cache->ebl == NULL))
461 : 0 : cache->ebl = (void *) -1l;
462 : : }
463 : :
464 : : /* Fetch the ABI's default CFI program. */
465 [ + - ]: 188 : if (likely (cache->ebl != (void *) -1l)
466 [ + - ]: 188 : && unlikely (ebl_abi_cfi (cache->ebl, &abi_info) < 0))
467 : : return DWARF_E_UNKNOWN_ERROR;
468 : :
469 : 188 : Dwarf_Frame *cie_fs = calloc (1, sizeof (Dwarf_Frame));
470 [ + - ]: 188 : if (unlikely (cie_fs == NULL))
471 : : return DWARF_E_NOMEM;
472 : :
473 : : /* If the default state of any register is not "undefined"
474 : : (i.e. call-clobbered), then the backend supplies instructions
475 : : for the standard initial state. */
476 [ + - ]: 188 : if (abi_info.initial_instructions_end > abi_info.initial_instructions)
477 : : {
478 : : /* Dummy CIE for backend's instructions. */
479 : 188 : struct dwarf_cie abi_cie =
480 : : {
481 : 188 : .code_alignment_factor = abi_info.code_alignment_factor,
482 : 188 : .data_alignment_factor = abi_info.data_alignment_factor,
483 : : };
484 : 188 : result = execute_cfi (cache, &abi_cie, &cie_fs,
485 : : abi_info.initial_instructions,
486 : : abi_info.initial_instructions_end, true,
487 : : 0, (Dwarf_Addr) -1l);
488 : : }
489 : :
490 : : /* Now run the CIE's initial instructions. */
491 [ + - ]: 188 : if (cie->initial_instructions_end > cie->initial_instructions
492 [ + - ]: 188 : && likely (result == DWARF_E_NOERROR))
493 : 188 : result = execute_cfi (cache, cie, &cie_fs,
494 : : cie->initial_instructions,
495 : : cie->initial_instructions_end, false,
496 : : 0, (Dwarf_Addr) -1l);
497 : :
498 [ + - ]: 188 : if (likely (result == DWARF_E_NOERROR))
499 : : {
500 : : /* Now we have the initial state of things that all
501 : : FDEs using this CIE will start from. */
502 : 188 : cie_fs->cache = cache;
503 : 188 : cie->initial_state = cie_fs;
504 : : }
505 : :
506 : : return result;
507 : : }
508 : :
509 : : int
510 : : internal_function
511 : 13508 : __libdw_frame_at_address (Dwarf_CFI *cache, struct dwarf_fde *fde,
512 : : Dwarf_Addr address, Dwarf_Frame **frame)
513 : : {
514 : 13508 : int result = cie_cache_initial_state (cache, fde->cie);
515 [ + - ]: 13508 : if (likely (result == DWARF_E_NOERROR))
516 : : {
517 : 13508 : Dwarf_Frame *fs = duplicate_frame_state (fde->cie->initial_state, NULL);
518 [ - + ]: 13508 : if (unlikely (fs == NULL))
519 : 0 : return DWARF_E_NOMEM;
520 : :
521 : 13508 : fs->fde = fde;
522 : 13508 : fs->start = fde->start;
523 : 13508 : fs->end = fde->end;
524 : :
525 : 13508 : result = execute_cfi (cache, fde->cie, &fs,
526 : : fde->instructions, fde->instructions_end, false,
527 : : fde->start, address);
528 [ + - ]: 13508 : if (likely (result == DWARF_E_NOERROR))
529 : 13508 : *frame = fs;
530 : : }
531 : : return result;
532 : : }
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