1 //===--------------------------- DwarfParser.hpp --------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
9 // Parses DWARF CFIs (FDEs and CIEs).
11 //===----------------------------------------------------------------------===//
13 #ifndef __DWARF_PARSER_HPP__
14 #define __DWARF_PARSER_HPP__
22 #include "libunwind.h"
25 #include "AddressSpace.hpp"
29 /// CFI_Parser does basic parsing of a CFI (Call Frame Information) records.
30 /// See Dwarf Spec for details:
31 /// http://refspecs.linuxbase.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html
36 typedef typename A::pint_t pint_t;
38 /// Information encoded in a CIE (Common Information Entry)
42 pint_t cieInstructions;
43 uint8_t pointerEncoding;
45 uint8_t personalityEncoding;
46 uint8_t personalityOffsetInCIE;
48 uint32_t codeAlignFactor;
51 bool fdesHaveAugmentationData;
54 /// Information about an FDE (Frame Description Entry)
58 pint_t fdeInstructions;
65 kMaxRegisterNumber = 120
67 enum RegisterSavedWhere {
70 kRegisterOffsetFromCFA,
72 kRegisterAtExpression,
75 struct RegisterLocation {
76 RegisterSavedWhere location;
79 /// Information about a frame layout and registers saved determined
80 /// by "running" the dwarf FDE "instructions"
83 int32_t cfaRegisterOffset; // CFA = (cfaRegister)+cfaRegisterOffset
84 int64_t cfaExpression; // CFA = expression
85 uint32_t spExtraArgSize;
86 uint32_t codeOffsetAtStackDecrement;
87 bool registersInOtherRegisters;
89 RegisterLocation savedRegisters[kMaxRegisterNumber];
92 struct PrologInfoStackEntry {
93 PrologInfoStackEntry(PrologInfoStackEntry *n, const PrologInfo &i)
95 PrologInfoStackEntry *next;
99 static bool findFDE(A &addressSpace, pint_t pc, pint_t ehSectionStart,
100 uint32_t sectionLength, pint_t fdeHint, FDE_Info *fdeInfo,
102 static const char *decodeFDE(A &addressSpace, pint_t fdeStart,
103 FDE_Info *fdeInfo, CIE_Info *cieInfo);
104 static bool parseFDEInstructions(A &addressSpace, const FDE_Info &fdeInfo,
105 const CIE_Info &cieInfo, pint_t upToPC,
106 PrologInfo *results);
108 static const char *parseCIE(A &addressSpace, pint_t cie, CIE_Info *cieInfo);
111 static bool parseInstructions(A &addressSpace, pint_t instructions,
112 pint_t instructionsEnd, const CIE_Info &cieInfo,
114 PrologInfoStackEntry *&rememberStack,
115 PrologInfo *results);
118 /// Parse a FDE into a CIE_Info and an FDE_Info
119 template <typename A>
120 const char *CFI_Parser<A>::decodeFDE(A &addressSpace, pint_t fdeStart,
121 FDE_Info *fdeInfo, CIE_Info *cieInfo) {
123 pint_t cfiLength = (pint_t)addressSpace.get32(p);
125 if (cfiLength == 0xffffffff) {
126 // 0xffffffff means length is really next 8 bytes
127 cfiLength = (pint_t)addressSpace.get64(p);
131 return "FDE has zero length"; // end marker
132 uint32_t ciePointer = addressSpace.get32(p);
134 return "FDE is really a CIE"; // this is a CIE not an FDE
135 pint_t nextCFI = p + cfiLength;
136 pint_t cieStart = p - ciePointer;
137 const char *err = parseCIE(addressSpace, cieStart, cieInfo);
141 // parse pc begin and range
143 addressSpace.getEncodedP(p, nextCFI, cieInfo->pointerEncoding);
145 addressSpace.getEncodedP(p, nextCFI, cieInfo->pointerEncoding & 0x0F);
146 // parse rest of info
148 // check for augmentation length
149 if (cieInfo->fdesHaveAugmentationData) {
150 pint_t augLen = (pint_t)addressSpace.getULEB128(p, nextCFI);
151 pint_t endOfAug = p + augLen;
152 if (cieInfo->lsdaEncoding != 0) {
153 // peek at value (without indirection). Zero means no lsda
154 pint_t lsdaStart = p;
155 if (addressSpace.getEncodedP(p, nextCFI, cieInfo->lsdaEncoding & 0x0F) !=
157 // reset pointer and re-parse lsda address
160 addressSpace.getEncodedP(p, nextCFI, cieInfo->lsdaEncoding);
165 fdeInfo->fdeStart = fdeStart;
166 fdeInfo->fdeLength = nextCFI - fdeStart;
167 fdeInfo->fdeInstructions = p;
168 fdeInfo->pcStart = pcStart;
169 fdeInfo->pcEnd = pcStart + pcRange;
170 return NULL; // success
173 /// Scan an eh_frame section to find an FDE for a pc
174 template <typename A>
175 bool CFI_Parser<A>::findFDE(A &addressSpace, pint_t pc, pint_t ehSectionStart,
176 uint32_t sectionLength, pint_t fdeHint,
177 FDE_Info *fdeInfo, CIE_Info *cieInfo) {
178 //fprintf(stderr, "findFDE(0x%llX)\n", (long long)pc);
179 pint_t p = (fdeHint != 0) ? fdeHint : ehSectionStart;
180 const pint_t ehSectionEnd = p + sectionLength;
181 while (p < ehSectionEnd) {
182 pint_t currentCFI = p;
183 //fprintf(stderr, "findFDE() CFI at 0x%llX\n", (long long)p);
184 pint_t cfiLength = addressSpace.get32(p);
186 if (cfiLength == 0xffffffff) {
187 // 0xffffffff means length is really next 8 bytes
188 cfiLength = (pint_t)addressSpace.get64(p);
192 return false; // end marker
193 uint32_t id = addressSpace.get32(p);
198 // process FDE to see if it covers pc
199 pint_t nextCFI = p + cfiLength;
200 uint32_t ciePointer = addressSpace.get32(p);
201 pint_t cieStart = p - ciePointer;
202 // validate pointer to CIE is within section
203 if ((ehSectionStart <= cieStart) && (cieStart < ehSectionEnd)) {
204 if (parseCIE(addressSpace, cieStart, cieInfo) == NULL) {
206 // parse pc begin and range
208 addressSpace.getEncodedP(p, nextCFI, cieInfo->pointerEncoding);
209 pint_t pcRange = addressSpace.getEncodedP(
210 p, nextCFI, cieInfo->pointerEncoding & 0x0F);
211 // test if pc is within the function this FDE covers
212 if ((pcStart < pc) && (pc <= pcStart + pcRange)) {
213 // parse rest of info
215 // check for augmentation length
216 if (cieInfo->fdesHaveAugmentationData) {
217 pint_t augLen = (pint_t)addressSpace.getULEB128(p, nextCFI);
218 pint_t endOfAug = p + augLen;
219 if (cieInfo->lsdaEncoding != 0) {
220 // peek at value (without indirection). Zero means no lsda
221 pint_t lsdaStart = p;
222 if (addressSpace.getEncodedP(
223 p, nextCFI, cieInfo->lsdaEncoding & 0x0F) != 0) {
224 // reset pointer and re-parse lsda address
226 fdeInfo->lsda = addressSpace
227 .getEncodedP(p, nextCFI, cieInfo->lsdaEncoding);
232 fdeInfo->fdeStart = currentCFI;
233 fdeInfo->fdeLength = nextCFI - currentCFI;
234 fdeInfo->fdeInstructions = p;
235 fdeInfo->pcStart = pcStart;
236 fdeInfo->pcEnd = pcStart + pcRange;
239 // pc is not in begin/range, skip this FDE
242 // malformed CIE, now augmentation describing pc range encoding
245 // malformed FDE. CIE is bad
253 /// Extract info from a CIE
254 template <typename A>
255 const char *CFI_Parser<A>::parseCIE(A &addressSpace, pint_t cie,
257 cieInfo->pointerEncoding = 0;
258 cieInfo->lsdaEncoding = 0;
259 cieInfo->personalityEncoding = 0;
260 cieInfo->personalityOffsetInCIE = 0;
261 cieInfo->personality = 0;
262 cieInfo->codeAlignFactor = 0;
263 cieInfo->dataAlignFactor = 0;
264 cieInfo->isSignalFrame = false;
265 cieInfo->fdesHaveAugmentationData = false;
266 cieInfo->cieStart = cie;
268 pint_t cieLength = (pint_t)addressSpace.get32(p);
270 pint_t cieContentEnd = p + cieLength;
271 if (cieLength == 0xffffffff) {
272 // 0xffffffff means length is really next 8 bytes
273 cieLength = (pint_t)addressSpace.get64(p);
275 cieContentEnd = p + cieLength;
279 // CIE ID is always 0
280 if (addressSpace.get32(p) != 0)
281 return "CIE ID is not zero";
283 // Version is always 1 or 3
284 uint8_t version = addressSpace.get8(p);
285 if ((version != 1) && (version != 3))
286 return "CIE version is not 1 or 3";
288 // save start of augmentation string and find end
290 while (addressSpace.get8(p) != 0)
293 // parse code aligment factor
294 cieInfo->codeAlignFactor = (uint32_t)addressSpace.getULEB128(p, cieContentEnd);
295 // parse data alignment factor
296 cieInfo->dataAlignFactor = (int)addressSpace.getSLEB128(p, cieContentEnd);
297 // parse return address register
298 addressSpace.getULEB128(p, cieContentEnd);
299 // parse augmentation data based on augmentation string
300 const char *result = NULL;
301 if (addressSpace.get8(strStart) == 'z') {
302 // parse augmentation data length
303 addressSpace.getULEB128(p, cieContentEnd);
304 for (pint_t s = strStart; addressSpace.get8(s) != '\0'; ++s) {
305 switch (addressSpace.get8(s)) {
307 cieInfo->fdesHaveAugmentationData = true;
310 cieInfo->personalityEncoding = addressSpace.get8(p);
312 cieInfo->personalityOffsetInCIE = (uint8_t)(p - cie);
313 cieInfo->personality = addressSpace
314 .getEncodedP(p, cieContentEnd, cieInfo->personalityEncoding);
317 cieInfo->lsdaEncoding = addressSpace.get8(p);
321 cieInfo->pointerEncoding = addressSpace.get8(p);
325 cieInfo->isSignalFrame = true;
328 // ignore unknown letters
333 cieInfo->cieLength = cieContentEnd - cieInfo->cieStart;
334 cieInfo->cieInstructions = p;
339 /// "run" the dwarf instructions and create the abstact PrologInfo for an FDE
340 template <typename A>
341 bool CFI_Parser<A>::parseFDEInstructions(A &addressSpace,
342 const FDE_Info &fdeInfo,
343 const CIE_Info &cieInfo, pint_t upToPC,
344 PrologInfo *results) {
346 bzero(results, sizeof(PrologInfo));
347 PrologInfoStackEntry *rememberStack = NULL;
349 // parse CIE then FDE instructions
350 return parseInstructions(addressSpace, cieInfo.cieInstructions,
351 cieInfo.cieStart + cieInfo.cieLength, cieInfo,
352 (pint_t)(-1), rememberStack, results) &&
353 parseInstructions(addressSpace, fdeInfo.fdeInstructions,
354 fdeInfo.fdeStart + fdeInfo.fdeLength, cieInfo,
355 upToPC - fdeInfo.pcStart, rememberStack, results);
358 /// "run" the dwarf instructions
359 template <typename A>
360 bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
361 pint_t instructionsEnd,
362 const CIE_Info &cieInfo, pint_t pcoffset,
363 PrologInfoStackEntry *&rememberStack,
364 PrologInfo *results) {
365 const bool logDwarf = false;
366 pint_t p = instructions;
367 pint_t codeOffset = 0;
368 PrologInfo initialState = *results;
370 fprintf(stderr, "parseInstructions(instructions=0x%0llX)\n",
371 (uint64_t) instructionsEnd);
373 // see Dwarf Spec, section 6.4.2 for details on unwind opcodes
374 while ((p < instructionsEnd) && (codeOffset < pcoffset)) {
379 uint8_t opcode = addressSpace.get8(p);
381 PrologInfoStackEntry *entry;
386 fprintf(stderr, "DW_CFA_nop\n");
390 addressSpace.getEncodedP(p, instructionsEnd, cieInfo.pointerEncoding);
392 fprintf(stderr, "DW_CFA_set_loc\n");
394 case DW_CFA_advance_loc1:
395 codeOffset += (addressSpace.get8(p) * cieInfo.codeAlignFactor);
398 fprintf(stderr, "DW_CFA_advance_loc1: new offset=%llu\n",
399 (uint64_t)codeOffset);
401 case DW_CFA_advance_loc2:
402 codeOffset += (addressSpace.get16(p) * cieInfo.codeAlignFactor);
405 fprintf(stderr, "DW_CFA_advance_loc2: new offset=%llu\n",
406 (uint64_t)codeOffset);
408 case DW_CFA_advance_loc4:
409 codeOffset += (addressSpace.get32(p) * cieInfo.codeAlignFactor);
412 fprintf(stderr, "DW_CFA_advance_loc4: new offset=%llu\n",
413 (uint64_t)codeOffset);
415 case DW_CFA_offset_extended:
416 reg = addressSpace.getULEB128(p, instructionsEnd);
417 offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd)
418 * cieInfo.dataAlignFactor;
419 if (reg > kMaxRegisterNumber) {
421 "malformed DW_CFA_offset_extended dwarf unwind, reg too big\n");
424 results->savedRegisters[reg].location = kRegisterInCFA;
425 results->savedRegisters[reg].value = offset;
427 fprintf(stderr, "DW_CFA_offset_extended(reg=%lld, offset=%lld)\n", reg,
430 case DW_CFA_restore_extended:
431 reg = addressSpace.getULEB128(p, instructionsEnd);
433 if (reg > kMaxRegisterNumber) {
436 "malformed DW_CFA_restore_extended dwarf unwind, reg too big\n");
439 results->savedRegisters[reg] = initialState.savedRegisters[reg];
441 fprintf(stderr, "DW_CFA_restore_extended(reg=%lld)\n", reg);
443 case DW_CFA_undefined:
444 reg = addressSpace.getULEB128(p, instructionsEnd);
445 if (reg > kMaxRegisterNumber) {
447 "malformed DW_CFA_undefined dwarf unwind, reg too big\n");
450 results->savedRegisters[reg].location = kRegisterUnused;
452 fprintf(stderr, "DW_CFA_undefined(reg=%lld)\n", reg);
454 case DW_CFA_same_value:
455 reg = addressSpace.getULEB128(p, instructionsEnd);
456 if (reg > kMaxRegisterNumber) {
458 "malformed DW_CFA_same_value dwarf unwind, reg too big\n");
461 // <rdar://problem/8456377> DW_CFA_same_value unsupported
462 // "same value" means register was stored in frame, but its current
463 // value has not changed, so no need to restore from frame.
464 // We model this as if the register was never saved.
465 results->savedRegisters[reg].location = kRegisterUnused;
466 // set flag to disable conversion to compact unwind
467 results->sameValueUsed = true;
469 fprintf(stderr, "DW_CFA_same_value(reg=%lld)\n", reg);
471 case DW_CFA_register:
472 reg = addressSpace.getULEB128(p, instructionsEnd);
473 reg2 = addressSpace.getULEB128(p, instructionsEnd);
474 if (reg > kMaxRegisterNumber) {
476 "malformed DW_CFA_register dwarf unwind, reg too big\n");
479 if (reg2 > kMaxRegisterNumber) {
481 "malformed DW_CFA_register dwarf unwind, reg2 too big\n");
484 results->savedRegisters[reg].location = kRegisterInRegister;
485 results->savedRegisters[reg].value = (int64_t)reg2;
486 // set flag to disable conversion to compact unwind
487 results->registersInOtherRegisters = true;
489 fprintf(stderr, "DW_CFA_register(reg=%lld, reg2=%lld)\n", reg, reg2);
491 case DW_CFA_remember_state:
492 // avoid operator new, because that would be an upward dependency
493 entry = (PrologInfoStackEntry *)malloc(sizeof(PrologInfoStackEntry));
495 entry->next = rememberStack;
496 entry->info = *results;
497 rememberStack = entry;
502 fprintf(stderr, "DW_CFA_remember_state\n");
504 case DW_CFA_restore_state:
505 if (rememberStack != NULL) {
506 PrologInfoStackEntry *top = rememberStack;
507 *results = top->info;
508 rememberStack = top->next;
514 fprintf(stderr, "DW_CFA_restore_state\n");
517 reg = addressSpace.getULEB128(p, instructionsEnd);
518 offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd);
519 if (reg > kMaxRegisterNumber) {
520 fprintf(stderr, "malformed DW_CFA_def_cfa dwarf unwind, reg too big\n");
523 results->cfaRegister = (uint32_t)reg;
524 results->cfaRegisterOffset = (int32_t)offset;
526 fprintf(stderr, "DW_CFA_def_cfa(reg=%lld, offset=%lld)\n", reg, offset);
528 case DW_CFA_def_cfa_register:
529 reg = addressSpace.getULEB128(p, instructionsEnd);
530 if (reg > kMaxRegisterNumber) {
533 "malformed DW_CFA_def_cfa_register dwarf unwind, reg too big\n");
536 results->cfaRegister = (uint32_t)reg;
538 fprintf(stderr, "DW_CFA_def_cfa_register(%lld)\n", reg);
540 case DW_CFA_def_cfa_offset:
541 results->cfaRegisterOffset = (int32_t)
542 addressSpace.getULEB128(p, instructionsEnd);
543 results->codeOffsetAtStackDecrement = (uint32_t)codeOffset;
545 fprintf(stderr, "DW_CFA_def_cfa_offset(%d)\n",
546 results->cfaRegisterOffset);
548 case DW_CFA_def_cfa_expression:
549 results->cfaRegister = 0;
550 results->cfaExpression = (int64_t)p;
551 length = addressSpace.getULEB128(p, instructionsEnd);
555 "DW_CFA_def_cfa_expression(expression=0x%llX, length=%llu)\n",
556 results->cfaExpression, length);
558 case DW_CFA_expression:
559 reg = addressSpace.getULEB128(p, instructionsEnd);
560 if (reg > kMaxRegisterNumber) {
562 "malformed DW_CFA_expression dwarf unwind, reg too big\n");
565 results->savedRegisters[reg].location = kRegisterAtExpression;
566 results->savedRegisters[reg].value = (int64_t)p;
567 length = addressSpace.getULEB128(p, instructionsEnd);
571 "DW_CFA_expression(reg=%lld, expression=0x%llX, length=%llu)\n",
572 reg, results->savedRegisters[reg].value, length);
574 case DW_CFA_offset_extended_sf:
575 reg = addressSpace.getULEB128(p, instructionsEnd);
576 if (reg > kMaxRegisterNumber) {
579 "malformed DW_CFA_offset_extended_sf dwarf unwind, reg too big\n");
583 addressSpace.getSLEB128(p, instructionsEnd) * cieInfo.dataAlignFactor;
584 results->savedRegisters[reg].location = kRegisterInCFA;
585 results->savedRegisters[reg].value = offset;
587 fprintf(stderr, "DW_CFA_offset_extended_sf(reg=%lld, offset=%lld)\n",
590 case DW_CFA_def_cfa_sf:
591 reg = addressSpace.getULEB128(p, instructionsEnd);
593 addressSpace.getSLEB128(p, instructionsEnd) * cieInfo.dataAlignFactor;
594 if (reg > kMaxRegisterNumber) {
596 "malformed DW_CFA_def_cfa_sf dwarf unwind, reg too big\n");
599 results->cfaRegister = (uint32_t)reg;
600 results->cfaRegisterOffset = (int32_t)offset;
602 fprintf(stderr, "DW_CFA_def_cfa_sf(reg=%lld, offset=%lld)\n", reg,
605 case DW_CFA_def_cfa_offset_sf:
606 results->cfaRegisterOffset = (int32_t)
607 (addressSpace.getSLEB128(p, instructionsEnd) * cieInfo.dataAlignFactor);
608 results->codeOffsetAtStackDecrement = (uint32_t)codeOffset;
610 fprintf(stderr, "DW_CFA_def_cfa_offset_sf(%d)\n",
611 results->cfaRegisterOffset);
613 case DW_CFA_val_offset:
614 reg = addressSpace.getULEB128(p, instructionsEnd);
615 offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd)
616 * cieInfo.dataAlignFactor;
617 results->savedRegisters[reg].location = kRegisterOffsetFromCFA;
618 results->savedRegisters[reg].value = offset;
620 fprintf(stderr, "DW_CFA_val_offset(reg=%lld, offset=%lld\n", reg,
623 case DW_CFA_val_offset_sf:
624 reg = addressSpace.getULEB128(p, instructionsEnd);
625 if (reg > kMaxRegisterNumber) {
627 "malformed DW_CFA_val_offset_sf dwarf unwind, reg too big\n");
631 addressSpace.getSLEB128(p, instructionsEnd) * cieInfo.dataAlignFactor;
632 results->savedRegisters[reg].location = kRegisterOffsetFromCFA;
633 results->savedRegisters[reg].value = offset;
635 fprintf(stderr, "DW_CFA_val_offset_sf(reg=%lld, offset=%lld\n", reg,
638 case DW_CFA_val_expression:
639 reg = addressSpace.getULEB128(p, instructionsEnd);
640 if (reg > kMaxRegisterNumber) {
642 "malformed DW_CFA_val_expression dwarf unwind, reg too big\n");
645 results->savedRegisters[reg].location = kRegisterIsExpression;
646 results->savedRegisters[reg].value = (int64_t)p;
647 length = addressSpace.getULEB128(p, instructionsEnd);
652 "DW_CFA_val_expression(reg=%lld, expression=0x%llX, length=%lld)\n",
653 reg, results->savedRegisters[reg].value, length);
655 case DW_CFA_GNU_args_size:
656 length = addressSpace.getULEB128(p, instructionsEnd);
657 results->spExtraArgSize = (uint32_t)length;
659 fprintf(stderr, "DW_CFA_GNU_args_size(%lld)\n", length);
661 case DW_CFA_GNU_negative_offset_extended:
662 reg = addressSpace.getULEB128(p, instructionsEnd);
663 if (reg > kMaxRegisterNumber) {
664 fprintf(stderr, "malformed DW_CFA_GNU_negative_offset_extended dwarf "
665 "unwind, reg too big\n");
668 offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd)
669 * cieInfo.dataAlignFactor;
670 results->savedRegisters[reg].location = kRegisterInCFA;
671 results->savedRegisters[reg].value = -offset;
673 fprintf(stderr, "DW_CFA_GNU_negative_offset_extended(%lld)\n", offset);
676 operand = opcode & 0x3F;
677 switch (opcode & 0xC0) {
680 offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd)
681 * cieInfo.dataAlignFactor;
682 results->savedRegisters[reg].location = kRegisterInCFA;
683 results->savedRegisters[reg].value = offset;
685 fprintf(stderr, "DW_CFA_offset(reg=%d, offset=%lld)\n", operand,
688 case DW_CFA_advance_loc:
689 codeOffset += operand * cieInfo.codeAlignFactor;
691 fprintf(stderr, "DW_CFA_advance_loc: new offset=%llu\n",
692 (uint64_t)codeOffset);
696 results->savedRegisters[reg] = initialState.savedRegisters[reg];
698 fprintf(stderr, "DW_CFA_restore(reg=%lld)\n", reg);
702 fprintf(stderr, "unknown CFA opcode 0x%02X\n", opcode);
711 } // namespace libunwind
713 #endif // __DWARF_PARSER_HPP__