1 //===-------------------------- DwarfInstructions.hpp ---------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //
9 //  Processor specific interpretation of DWARF unwind info.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef __DWARF_INSTRUCTIONS_HPP__
14 #define __DWARF_INSTRUCTIONS_HPP__
15 
16 #include <stdint.h>
17 #include <stdio.h>
18 #include <stdlib.h>
19 
20 #include "dwarf2.h"
21 #include "Registers.hpp"
22 #include "DwarfParser.hpp"
23 #include "config.h"
24 
25 
26 namespace libunwind {
27 
28 
29 /// DwarfInstructions maps abtract DWARF unwind instructions to a particular
30 /// architecture
31 template <typename A, typename R>
32 class DwarfInstructions {
33 public:
34   typedef typename A::pint_t pint_t;
35   typedef typename A::sint_t sint_t;
36 
37   static int stepWithDwarf(A &addressSpace, pint_t pc, pint_t fdeStart,
38                            R &registers);
39 
40 private:
41 
42   enum {
43     DW_X86_64_RET_ADDR = 16
44   };
45 
46   enum {
47     DW_X86_RET_ADDR = 8
48   };
49 
50   typedef typename CFI_Parser<A>::RegisterLocation  RegisterLocation;
51   typedef typename CFI_Parser<A>::PrologInfo        PrologInfo;
52   typedef typename CFI_Parser<A>::FDE_Info          FDE_Info;
53   typedef typename CFI_Parser<A>::CIE_Info          CIE_Info;
54 
55   static pint_t evaluateExpression(pint_t expression, A &addressSpace,
56                                    const R &registers,
57                                    pint_t initialStackValue);
58   static pint_t getSavedRegister(A &addressSpace, const R &registers,
59                                  pint_t cfa, const RegisterLocation &savedReg);
60   static double getSavedFloatRegister(A &addressSpace, const R &registers,
61                                   pint_t cfa, const RegisterLocation &savedReg);
62   static v128 getSavedVectorRegister(A &addressSpace, const R &registers,
63                                   pint_t cfa, const RegisterLocation &savedReg);
64 
65   static pint_t getCFA(A &addressSpace, const PrologInfo &prolog,
66                        const R &registers) {
67     if (prolog.cfaRegister != 0)
68       return (pint_t)((sint_t)registers.getRegister((int)prolog.cfaRegister) +
69              prolog.cfaRegisterOffset);
70     if (prolog.cfaExpression != 0)
71       return evaluateExpression((pint_t)prolog.cfaExpression, addressSpace,
72                                 registers, 0);
73     assert(0 && "getCFA(): unknown location");
74     __builtin_unreachable();
75   }
76 };
77 
78 
79 template <typename A, typename R>
80 typename A::pint_t DwarfInstructions<A, R>::getSavedRegister(
81     A &addressSpace, const R &registers, pint_t cfa,
82     const RegisterLocation &savedReg) {
83   switch (savedReg.location) {
84   case CFI_Parser<A>::kRegisterInCFA:
85     return addressSpace.getRegister(cfa + (pint_t)savedReg.value);
86 
87   case CFI_Parser<A>::kRegisterAtExpression:
88     return addressSpace.getRegister(
89         evaluateExpression((pint_t)savedReg.value, addressSpace,
90                             registers, cfa));
91 
92   case CFI_Parser<A>::kRegisterIsExpression:
93     return evaluateExpression((pint_t)savedReg.value, addressSpace,
94                               registers, cfa);
95 
96   case CFI_Parser<A>::kRegisterInRegister:
97     return registers.getRegister((int)savedReg.value);
98 
99   case CFI_Parser<A>::kRegisterUnused:
100   case CFI_Parser<A>::kRegisterOffsetFromCFA:
101     // FIX ME
102     break;
103   }
104   _LIBUNWIND_ABORT("unsupported restore location for register");
105 }
106 
107 template <typename A, typename R>
108 double DwarfInstructions<A, R>::getSavedFloatRegister(
109     A &addressSpace, const R &registers, pint_t cfa,
110     const RegisterLocation &savedReg) {
111   switch (savedReg.location) {
112   case CFI_Parser<A>::kRegisterInCFA:
113     return addressSpace.getDouble(cfa + (pint_t)savedReg.value);
114 
115   case CFI_Parser<A>::kRegisterAtExpression:
116     return addressSpace.getDouble(
117         evaluateExpression((pint_t)savedReg.value, addressSpace,
118                             registers, cfa));
119 
120   case CFI_Parser<A>::kRegisterIsExpression:
121   case CFI_Parser<A>::kRegisterUnused:
122   case CFI_Parser<A>::kRegisterOffsetFromCFA:
123   case CFI_Parser<A>::kRegisterInRegister:
124     // FIX ME
125     break;
126   }
127   _LIBUNWIND_ABORT("unsupported restore location for float register");
128 }
129 
130 template <typename A, typename R>
131 v128 DwarfInstructions<A, R>::getSavedVectorRegister(
132     A &addressSpace, const R &registers, pint_t cfa,
133     const RegisterLocation &savedReg) {
134   switch (savedReg.location) {
135   case CFI_Parser<A>::kRegisterInCFA:
136     return addressSpace.getVector(cfa + (pint_t)savedReg.value);
137 
138   case CFI_Parser<A>::kRegisterAtExpression:
139     return addressSpace.getVector(
140         evaluateExpression((pint_t)savedReg.value, addressSpace,
141                             registers, cfa));
142 
143   case CFI_Parser<A>::kRegisterIsExpression:
144   case CFI_Parser<A>::kRegisterUnused:
145   case CFI_Parser<A>::kRegisterOffsetFromCFA:
146   case CFI_Parser<A>::kRegisterInRegister:
147     // FIX ME
148     break;
149   }
150   _LIBUNWIND_ABORT("unsupported restore location for vector register");
151 }
152 
153 template <typename A, typename R>
154 int DwarfInstructions<A, R>::stepWithDwarf(A &addressSpace, pint_t pc,
155                                            pint_t fdeStart, R &registers) {
156   FDE_Info fdeInfo;
157   CIE_Info cieInfo;
158   if (CFI_Parser<A>::decodeFDE(addressSpace, fdeStart, &fdeInfo,
159                                &cieInfo) == NULL) {
160     PrologInfo prolog;
161     if (CFI_Parser<A>::parseFDEInstructions(addressSpace, fdeInfo, cieInfo, pc,
162                                             &prolog)) {
163       // get pointer to cfa (architecture specific)
164       pint_t cfa = getCFA(addressSpace, prolog, registers);
165 
166        // restore registers that DWARF says were saved
167       R newRegisters = registers;
168       pint_t returnAddress = 0;
169       const int lastReg = R::lastDwarfRegNum();
170       assert(static_cast<int>(CFI_Parser<A>::kMaxRegisterNumber) >= lastReg &&
171              "register range too large");
172       assert(lastReg >= (int)cieInfo.returnAddressRegister &&
173              "register range does not contain return address register");
174       for (int i = 0; i <= lastReg; ++i) {
175         if (prolog.savedRegisters[i].location !=
176             CFI_Parser<A>::kRegisterUnused) {
177           if (registers.validFloatRegister(i))
178             newRegisters.setFloatRegister(
179                 i, getSavedFloatRegister(addressSpace, registers, cfa,
180                                          prolog.savedRegisters[i]));
181           else if (registers.validVectorRegister(i))
182             newRegisters.setVectorRegister(
183                 i, getSavedVectorRegister(addressSpace, registers, cfa,
184                                           prolog.savedRegisters[i]));
185           else if (i == (int)cieInfo.returnAddressRegister)
186             returnAddress = getSavedRegister(addressSpace, registers, cfa,
187                                              prolog.savedRegisters[i]);
188           else if (registers.validRegister(i))
189             newRegisters.setRegister(
190                 i, getSavedRegister(addressSpace, registers, cfa,
191                                     prolog.savedRegisters[i]));
192           else
193             return UNW_EBADREG;
194         }
195       }
196 
197       // By definition, the CFA is the stack pointer at the call site, so
198       // restoring SP means setting it to CFA.
199       newRegisters.setSP(cfa);
200 
201 #if defined(_LIBUNWIND_TARGET_AARCH64)
202       // If the target is aarch64 then the return address may have been signed
203       // using the v8.3 pointer authentication extensions. The original
204       // return address needs to be authenticated before the return address is
205       // restored. autia1716 is used instead of autia as autia1716 assembles
206       // to a NOP on pre-v8.3a architectures.
207       if (prolog.savedRegisters[UNW_ARM64_RA_SIGN_STATE].value) {
208 #if !defined(_LIBUNWIND_IS_NATIVE_ONLY)
209         return UNW_ECROSSRASIGNING;
210 #else
211         register unsigned long long x17 __asm("x17") = returnAddress;
212         register unsigned long long x16 __asm("x16") = cfa;
213 
214         // These are the autia1716/autib1716 instructions. The hint instructions
215         // are used here as gcc does not assemble autia1716/autib1716 for pre
216         // armv8.3a targets.
217         if (cieInfo.addressesSignedWithBKey)
218           asm("hint 0xe" : "+r"(x17) : "r"(x16)); // autib1716
219         else
220           asm("hint 0xc" : "+r"(x17) : "r"(x16)); // autia1716
221         returnAddress = x17;
222 #endif
223       }
224 #endif
225 
226 #if defined(_LIBUNWIND_TARGET_SPARC)
227       // Skip call site instruction and delay slot
228       returnAddress += 8;
229       // Skip unimp instruction if function returns a struct
230       if ((addressSpace.get32(returnAddress) & 0xC1C00000) == 0)
231         returnAddress += 4;
232 #endif
233 
234       // Return address is address after call site instruction, so setting IP to
235       // that does simualates a return.
236       newRegisters.setIP(returnAddress);
237 
238       // Simulate the step by replacing the register set with the new ones.
239       registers = newRegisters;
240 
241       return UNW_STEP_SUCCESS;
242     }
243   }
244   return UNW_EBADFRAME;
245 }
246 
247 template <typename A, typename R>
248 typename A::pint_t
249 DwarfInstructions<A, R>::evaluateExpression(pint_t expression, A &addressSpace,
250                                             const R &registers,
251                                             pint_t initialStackValue) {
252   const bool log = false;
253   pint_t p = expression;
254   pint_t expressionEnd = expression + 20; // temp, until len read
255   pint_t length = (pint_t)addressSpace.getULEB128(p, expressionEnd);
256   expressionEnd = p + length;
257   if (log)
258     fprintf(stderr, "evaluateExpression(): length=%" PRIu64 "\n",
259             (uint64_t)length);
260   pint_t stack[100];
261   pint_t *sp = stack;
262   *(++sp) = initialStackValue;
263 
264   while (p < expressionEnd) {
265     if (log) {
266       for (pint_t *t = sp; t > stack; --t) {
267         fprintf(stderr, "sp[] = 0x%" PRIx64 "\n", (uint64_t)(*t));
268       }
269     }
270     uint8_t opcode = addressSpace.get8(p++);
271     sint_t svalue, svalue2;
272     pint_t value;
273     uint32_t reg;
274     switch (opcode) {
275     case DW_OP_addr:
276       // push immediate address sized value
277       value = addressSpace.getP(p);
278       p += sizeof(pint_t);
279       *(++sp) = value;
280       if (log)
281         fprintf(stderr, "push 0x%" PRIx64 "\n", (uint64_t)value);
282       break;
283 
284     case DW_OP_deref:
285       // pop stack, dereference, push result
286       value = *sp--;
287       *(++sp) = addressSpace.getP(value);
288       if (log)
289         fprintf(stderr, "dereference 0x%" PRIx64 "\n", (uint64_t)value);
290       break;
291 
292     case DW_OP_const1u:
293       // push immediate 1 byte value
294       value = addressSpace.get8(p);
295       p += 1;
296       *(++sp) = value;
297       if (log)
298         fprintf(stderr, "push 0x%" PRIx64 "\n", (uint64_t)value);
299       break;
300 
301     case DW_OP_const1s:
302       // push immediate 1 byte signed value
303       svalue = (int8_t) addressSpace.get8(p);
304       p += 1;
305       *(++sp) = (pint_t)svalue;
306       if (log)
307         fprintf(stderr, "push 0x%" PRIx64 "\n", (uint64_t)svalue);
308       break;
309 
310     case DW_OP_const2u:
311       // push immediate 2 byte value
312       value = addressSpace.get16(p);
313       p += 2;
314       *(++sp) = value;
315       if (log)
316         fprintf(stderr, "push 0x%" PRIx64 "\n", (uint64_t)value);
317       break;
318 
319     case DW_OP_const2s:
320       // push immediate 2 byte signed value
321       svalue = (int16_t) addressSpace.get16(p);
322       p += 2;
323       *(++sp) = (pint_t)svalue;
324       if (log)
325         fprintf(stderr, "push 0x%" PRIx64 "\n", (uint64_t)svalue);
326       break;
327 
328     case DW_OP_const4u:
329       // push immediate 4 byte value
330       value = addressSpace.get32(p);
331       p += 4;
332       *(++sp) = value;
333       if (log)
334         fprintf(stderr, "push 0x%" PRIx64 "\n", (uint64_t)value);
335       break;
336 
337     case DW_OP_const4s:
338       // push immediate 4 byte signed value
339       svalue = (int32_t)addressSpace.get32(p);
340       p += 4;
341       *(++sp) = (pint_t)svalue;
342       if (log)
343         fprintf(stderr, "push 0x%" PRIx64 "\n", (uint64_t)svalue);
344       break;
345 
346     case DW_OP_const8u:
347       // push immediate 8 byte value
348       value = (pint_t)addressSpace.get64(p);
349       p += 8;
350       *(++sp) = value;
351       if (log)
352         fprintf(stderr, "push 0x%" PRIx64 "\n", (uint64_t)value);
353       break;
354 
355     case DW_OP_const8s:
356       // push immediate 8 byte signed value
357       value = (pint_t)addressSpace.get64(p);
358       p += 8;
359       *(++sp) = value;
360       if (log)
361         fprintf(stderr, "push 0x%" PRIx64 "\n", (uint64_t)value);
362       break;
363 
364     case DW_OP_constu:
365       // push immediate ULEB128 value
366       value = (pint_t)addressSpace.getULEB128(p, expressionEnd);
367       *(++sp) = value;
368       if (log)
369         fprintf(stderr, "push 0x%" PRIx64 "\n", (uint64_t)value);
370       break;
371 
372     case DW_OP_consts:
373       // push immediate SLEB128 value
374       svalue = (sint_t)addressSpace.getSLEB128(p, expressionEnd);
375       *(++sp) = (pint_t)svalue;
376       if (log)
377         fprintf(stderr, "push 0x%" PRIx64 "\n", (uint64_t)svalue);
378       break;
379 
380     case DW_OP_dup:
381       // push top of stack
382       value = *sp;
383       *(++sp) = value;
384       if (log)
385         fprintf(stderr, "duplicate top of stack\n");
386       break;
387 
388     case DW_OP_drop:
389       // pop
390       --sp;
391       if (log)
392         fprintf(stderr, "pop top of stack\n");
393       break;
394 
395     case DW_OP_over:
396       // dup second
397       value = sp[-1];
398       *(++sp) = value;
399       if (log)
400         fprintf(stderr, "duplicate second in stack\n");
401       break;
402 
403     case DW_OP_pick:
404       // pick from
405       reg = addressSpace.get8(p);
406       p += 1;
407       value = sp[-reg];
408       *(++sp) = value;
409       if (log)
410         fprintf(stderr, "duplicate %d in stack\n", reg);
411       break;
412 
413     case DW_OP_swap:
414       // swap top two
415       value = sp[0];
416       sp[0] = sp[-1];
417       sp[-1] = value;
418       if (log)
419         fprintf(stderr, "swap top of stack\n");
420       break;
421 
422     case DW_OP_rot:
423       // rotate top three
424       value = sp[0];
425       sp[0] = sp[-1];
426       sp[-1] = sp[-2];
427       sp[-2] = value;
428       if (log)
429         fprintf(stderr, "rotate top three of stack\n");
430       break;
431 
432     case DW_OP_xderef:
433       // pop stack, dereference, push result
434       value = *sp--;
435       *sp = *((pint_t*)value);
436       if (log)
437         fprintf(stderr, "x-dereference 0x%" PRIx64 "\n", (uint64_t)value);
438       break;
439 
440     case DW_OP_abs:
441       svalue = (sint_t)*sp;
442       if (svalue < 0)
443         *sp = (pint_t)(-svalue);
444       if (log)
445         fprintf(stderr, "abs\n");
446       break;
447 
448     case DW_OP_and:
449       value = *sp--;
450       *sp &= value;
451       if (log)
452         fprintf(stderr, "and\n");
453       break;
454 
455     case DW_OP_div:
456       svalue = (sint_t)(*sp--);
457       svalue2 = (sint_t)*sp;
458       *sp = (pint_t)(svalue2 / svalue);
459       if (log)
460         fprintf(stderr, "div\n");
461       break;
462 
463     case DW_OP_minus:
464       value = *sp--;
465       *sp = *sp - value;
466       if (log)
467         fprintf(stderr, "minus\n");
468       break;
469 
470     case DW_OP_mod:
471       svalue = (sint_t)(*sp--);
472       svalue2 = (sint_t)*sp;
473       *sp = (pint_t)(svalue2 % svalue);
474       if (log)
475         fprintf(stderr, "module\n");
476       break;
477 
478     case DW_OP_mul:
479       svalue = (sint_t)(*sp--);
480       svalue2 = (sint_t)*sp;
481       *sp = (pint_t)(svalue2 * svalue);
482       if (log)
483         fprintf(stderr, "mul\n");
484       break;
485 
486     case DW_OP_neg:
487       *sp = 0 - *sp;
488       if (log)
489         fprintf(stderr, "neg\n");
490       break;
491 
492     case DW_OP_not:
493       svalue = (sint_t)(*sp);
494       *sp = (pint_t)(~svalue);
495       if (log)
496         fprintf(stderr, "not\n");
497       break;
498 
499     case DW_OP_or:
500       value = *sp--;
501       *sp |= value;
502       if (log)
503         fprintf(stderr, "or\n");
504       break;
505 
506     case DW_OP_plus:
507       value = *sp--;
508       *sp += value;
509       if (log)
510         fprintf(stderr, "plus\n");
511       break;
512 
513     case DW_OP_plus_uconst:
514       // pop stack, add uelb128 constant, push result
515       *sp += static_cast<pint_t>(addressSpace.getULEB128(p, expressionEnd));
516       if (log)
517         fprintf(stderr, "add constant\n");
518       break;
519 
520     case DW_OP_shl:
521       value = *sp--;
522       *sp = *sp << value;
523       if (log)
524         fprintf(stderr, "shift left\n");
525       break;
526 
527     case DW_OP_shr:
528       value = *sp--;
529       *sp = *sp >> value;
530       if (log)
531         fprintf(stderr, "shift left\n");
532       break;
533 
534     case DW_OP_shra:
535       value = *sp--;
536       svalue = (sint_t)*sp;
537       *sp = (pint_t)(svalue >> value);
538       if (log)
539         fprintf(stderr, "shift left arithmetric\n");
540       break;
541 
542     case DW_OP_xor:
543       value = *sp--;
544       *sp ^= value;
545       if (log)
546         fprintf(stderr, "xor\n");
547       break;
548 
549     case DW_OP_skip:
550       svalue = (int16_t) addressSpace.get16(p);
551       p += 2;
552       p = (pint_t)((sint_t)p + svalue);
553       if (log)
554         fprintf(stderr, "skip %" PRIu64 "\n", (uint64_t)svalue);
555       break;
556 
557     case DW_OP_bra:
558       svalue = (int16_t) addressSpace.get16(p);
559       p += 2;
560       if (*sp--)
561         p = (pint_t)((sint_t)p + svalue);
562       if (log)
563         fprintf(stderr, "bra %" PRIu64 "\n", (uint64_t)svalue);
564       break;
565 
566     case DW_OP_eq:
567       value = *sp--;
568       *sp = (*sp == value);
569       if (log)
570         fprintf(stderr, "eq\n");
571       break;
572 
573     case DW_OP_ge:
574       value = *sp--;
575       *sp = (*sp >= value);
576       if (log)
577         fprintf(stderr, "ge\n");
578       break;
579 
580     case DW_OP_gt:
581       value = *sp--;
582       *sp = (*sp > value);
583       if (log)
584         fprintf(stderr, "gt\n");
585       break;
586 
587     case DW_OP_le:
588       value = *sp--;
589       *sp = (*sp <= value);
590       if (log)
591         fprintf(stderr, "le\n");
592       break;
593 
594     case DW_OP_lt:
595       value = *sp--;
596       *sp = (*sp < value);
597       if (log)
598         fprintf(stderr, "lt\n");
599       break;
600 
601     case DW_OP_ne:
602       value = *sp--;
603       *sp = (*sp != value);
604       if (log)
605         fprintf(stderr, "ne\n");
606       break;
607 
608     case DW_OP_lit0:
609     case DW_OP_lit1:
610     case DW_OP_lit2:
611     case DW_OP_lit3:
612     case DW_OP_lit4:
613     case DW_OP_lit5:
614     case DW_OP_lit6:
615     case DW_OP_lit7:
616     case DW_OP_lit8:
617     case DW_OP_lit9:
618     case DW_OP_lit10:
619     case DW_OP_lit11:
620     case DW_OP_lit12:
621     case DW_OP_lit13:
622     case DW_OP_lit14:
623     case DW_OP_lit15:
624     case DW_OP_lit16:
625     case DW_OP_lit17:
626     case DW_OP_lit18:
627     case DW_OP_lit19:
628     case DW_OP_lit20:
629     case DW_OP_lit21:
630     case DW_OP_lit22:
631     case DW_OP_lit23:
632     case DW_OP_lit24:
633     case DW_OP_lit25:
634     case DW_OP_lit26:
635     case DW_OP_lit27:
636     case DW_OP_lit28:
637     case DW_OP_lit29:
638     case DW_OP_lit30:
639     case DW_OP_lit31:
640       value = static_cast<pint_t>(opcode - DW_OP_lit0);
641       *(++sp) = value;
642       if (log)
643         fprintf(stderr, "push literal 0x%" PRIx64 "\n", (uint64_t)value);
644       break;
645 
646     case DW_OP_reg0:
647     case DW_OP_reg1:
648     case DW_OP_reg2:
649     case DW_OP_reg3:
650     case DW_OP_reg4:
651     case DW_OP_reg5:
652     case DW_OP_reg6:
653     case DW_OP_reg7:
654     case DW_OP_reg8:
655     case DW_OP_reg9:
656     case DW_OP_reg10:
657     case DW_OP_reg11:
658     case DW_OP_reg12:
659     case DW_OP_reg13:
660     case DW_OP_reg14:
661     case DW_OP_reg15:
662     case DW_OP_reg16:
663     case DW_OP_reg17:
664     case DW_OP_reg18:
665     case DW_OP_reg19:
666     case DW_OP_reg20:
667     case DW_OP_reg21:
668     case DW_OP_reg22:
669     case DW_OP_reg23:
670     case DW_OP_reg24:
671     case DW_OP_reg25:
672     case DW_OP_reg26:
673     case DW_OP_reg27:
674     case DW_OP_reg28:
675     case DW_OP_reg29:
676     case DW_OP_reg30:
677     case DW_OP_reg31:
678       reg = static_cast<uint32_t>(opcode - DW_OP_reg0);
679       *(++sp) = registers.getRegister((int)reg);
680       if (log)
681         fprintf(stderr, "push reg %d\n", reg);
682       break;
683 
684     case DW_OP_regx:
685       reg = static_cast<uint32_t>(addressSpace.getULEB128(p, expressionEnd));
686       *(++sp) = registers.getRegister((int)reg);
687       if (log)
688         fprintf(stderr, "push reg %d + 0x%" PRIx64 "\n", reg, (uint64_t)svalue);
689       break;
690 
691     case DW_OP_breg0:
692     case DW_OP_breg1:
693     case DW_OP_breg2:
694     case DW_OP_breg3:
695     case DW_OP_breg4:
696     case DW_OP_breg5:
697     case DW_OP_breg6:
698     case DW_OP_breg7:
699     case DW_OP_breg8:
700     case DW_OP_breg9:
701     case DW_OP_breg10:
702     case DW_OP_breg11:
703     case DW_OP_breg12:
704     case DW_OP_breg13:
705     case DW_OP_breg14:
706     case DW_OP_breg15:
707     case DW_OP_breg16:
708     case DW_OP_breg17:
709     case DW_OP_breg18:
710     case DW_OP_breg19:
711     case DW_OP_breg20:
712     case DW_OP_breg21:
713     case DW_OP_breg22:
714     case DW_OP_breg23:
715     case DW_OP_breg24:
716     case DW_OP_breg25:
717     case DW_OP_breg26:
718     case DW_OP_breg27:
719     case DW_OP_breg28:
720     case DW_OP_breg29:
721     case DW_OP_breg30:
722     case DW_OP_breg31:
723       reg = static_cast<uint32_t>(opcode - DW_OP_breg0);
724       svalue = (sint_t)addressSpace.getSLEB128(p, expressionEnd);
725       svalue += static_cast<sint_t>(registers.getRegister((int)reg));
726       *(++sp) = (pint_t)(svalue);
727       if (log)
728         fprintf(stderr, "push reg %d + 0x%" PRIx64 "\n", reg, (uint64_t)svalue);
729       break;
730 
731     case DW_OP_bregx:
732       reg = static_cast<uint32_t>(addressSpace.getULEB128(p, expressionEnd));
733       svalue = (sint_t)addressSpace.getSLEB128(p, expressionEnd);
734       svalue += static_cast<sint_t>(registers.getRegister((int)reg));
735       *(++sp) = (pint_t)(svalue);
736       if (log)
737         fprintf(stderr, "push reg %d + 0x%" PRIx64 "\n", reg, (uint64_t)svalue);
738       break;
739 
740     case DW_OP_fbreg:
741       _LIBUNWIND_ABORT("DW_OP_fbreg not implemented");
742       break;
743 
744     case DW_OP_piece:
745       _LIBUNWIND_ABORT("DW_OP_piece not implemented");
746       break;
747 
748     case DW_OP_deref_size:
749       // pop stack, dereference, push result
750       value = *sp--;
751       switch (addressSpace.get8(p++)) {
752       case 1:
753         value = addressSpace.get8(value);
754         break;
755       case 2:
756         value = addressSpace.get16(value);
757         break;
758       case 4:
759         value = addressSpace.get32(value);
760         break;
761       case 8:
762         value = (pint_t)addressSpace.get64(value);
763         break;
764       default:
765         _LIBUNWIND_ABORT("DW_OP_deref_size with bad size");
766       }
767       *(++sp) = value;
768       if (log)
769         fprintf(stderr, "sized dereference 0x%" PRIx64 "\n", (uint64_t)value);
770       break;
771 
772     case DW_OP_xderef_size:
773     case DW_OP_nop:
774     case DW_OP_push_object_addres:
775     case DW_OP_call2:
776     case DW_OP_call4:
777     case DW_OP_call_ref:
778     default:
779       _LIBUNWIND_ABORT("DWARF opcode not implemented");
780     }
781 
782   }
783   if (log)
784     fprintf(stderr, "expression evaluates to 0x%" PRIx64 "\n", (uint64_t)*sp);
785   return *sp;
786 }
787 
788 
789 
790 } // namespace libunwind
791 
792 #endif // __DWARF_INSTRUCTIONS_HPP__
793