xref: /freebsd/contrib/llvm-project/libunwind/src/AddressSpace.hpp (revision 18054d0220cfc8df9c9568c437bd6fbb59d53c3c)
1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //
8 // Abstracts accessing local vs remote address spaces.
9 //
10 //===----------------------------------------------------------------------===//
11 
12 #ifndef __ADDRESSSPACE_HPP__
13 #define __ADDRESSSPACE_HPP__
14 
15 #include <stdint.h>
16 #include <stdio.h>
17 #include <stdlib.h>
18 #include <string.h>
19 
20 #include "libunwind.h"
21 #include "config.h"
22 #include "dwarf2.h"
23 #include "EHHeaderParser.hpp"
24 #include "Registers.hpp"
25 
26 #ifndef _LIBUNWIND_USE_DLADDR
27   #if !defined(_LIBUNWIND_IS_BAREMETAL) && !defined(_WIN32)
28     #define _LIBUNWIND_USE_DLADDR 1
29   #else
30     #define _LIBUNWIND_USE_DLADDR 0
31   #endif
32 #endif
33 
34 #if _LIBUNWIND_USE_DLADDR
35 #include <dlfcn.h>
36 #if defined(__ELF__) && defined(_LIBUNWIND_LINK_DL_LIB)
37 #pragma comment(lib, "dl")
38 #endif
39 #endif
40 
41 #if defined(_LIBUNWIND_ARM_EHABI)
42 struct EHABIIndexEntry {
43   uint32_t functionOffset;
44   uint32_t data;
45 };
46 #endif
47 
48 #ifdef __APPLE__
49 
50   struct dyld_unwind_sections
51   {
52     const struct mach_header*   mh;
53     const void*                 dwarf_section;
54     uintptr_t                   dwarf_section_length;
55     const void*                 compact_unwind_section;
56     uintptr_t                   compact_unwind_section_length;
57   };
58 
59   // In 10.7.0 or later, libSystem.dylib implements this function.
60   extern "C" bool _dyld_find_unwind_sections(void *, dyld_unwind_sections *);
61 
62 #elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_LIBUNWIND_IS_BAREMETAL)
63 
64 // When statically linked on bare-metal, the symbols for the EH table are looked
65 // up without going through the dynamic loader.
66 
67 // The following linker script may be used to produce the necessary sections and symbols.
68 // Unless the --eh-frame-hdr linker option is provided, the section is not generated
69 // and does not take space in the output file.
70 //
71 //   .eh_frame :
72 //   {
73 //       __eh_frame_start = .;
74 //       KEEP(*(.eh_frame))
75 //       __eh_frame_end = .;
76 //   }
77 //
78 //   .eh_frame_hdr :
79 //   {
80 //       KEEP(*(.eh_frame_hdr))
81 //   }
82 //
83 //   __eh_frame_hdr_start = SIZEOF(.eh_frame_hdr) > 0 ? ADDR(.eh_frame_hdr) : 0;
84 //   __eh_frame_hdr_end = SIZEOF(.eh_frame_hdr) > 0 ? . : 0;
85 
86 extern char __eh_frame_start;
87 extern char __eh_frame_end;
88 
89 #if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
90 extern char __eh_frame_hdr_start;
91 extern char __eh_frame_hdr_end;
92 #endif
93 
94 #elif defined(_LIBUNWIND_ARM_EHABI) && defined(_LIBUNWIND_IS_BAREMETAL)
95 
96 // When statically linked on bare-metal, the symbols for the EH table are looked
97 // up without going through the dynamic loader.
98 extern char __exidx_start;
99 extern char __exidx_end;
100 
101 #elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_WIN32)
102 
103 #include <windows.h>
104 #include <psapi.h>
105 
106 #elif defined(_LIBUNWIND_USE_DL_ITERATE_PHDR) ||                               \
107       defined(_LIBUNWIND_USE_DL_UNWIND_FIND_EXIDX)
108 
109 #include <link.h>
110 
111 #endif
112 
113 namespace libunwind {
114 
115 /// Used by findUnwindSections() to return info about needed sections.
116 struct UnwindInfoSections {
117 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) ||                                \
118     defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND) ||                              \
119     defined(_LIBUNWIND_USE_DL_ITERATE_PHDR)
120   // No dso_base for SEH.
121   uintptr_t       dso_base;
122 #endif
123 #if defined(_LIBUNWIND_USE_DL_ITERATE_PHDR)
124   size_t          text_segment_length;
125 #endif
126 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
127   uintptr_t       dwarf_section;
128   size_t          dwarf_section_length;
129 #endif
130 #if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
131   uintptr_t       dwarf_index_section;
132   size_t          dwarf_index_section_length;
133 #endif
134 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
135   uintptr_t       compact_unwind_section;
136   size_t          compact_unwind_section_length;
137 #endif
138 #if defined(_LIBUNWIND_ARM_EHABI)
139   uintptr_t       arm_section;
140   size_t          arm_section_length;
141 #endif
142 };
143 
144 
145 /// LocalAddressSpace is used as a template parameter to UnwindCursor when
146 /// unwinding a thread in the same process.  The wrappers compile away,
147 /// making local unwinds fast.
148 class _LIBUNWIND_HIDDEN LocalAddressSpace {
149 public:
150   typedef uintptr_t pint_t;
151   typedef intptr_t  sint_t;
152   uint8_t         get8(pint_t addr) {
153     uint8_t val;
154     memcpy(&val, (void *)addr, sizeof(val));
155     return val;
156   }
157   uint16_t         get16(pint_t addr) {
158     uint16_t val;
159     memcpy(&val, (void *)addr, sizeof(val));
160     return val;
161   }
162   uint32_t         get32(pint_t addr) {
163     uint32_t val;
164     memcpy(&val, (void *)addr, sizeof(val));
165     return val;
166   }
167   uint64_t         get64(pint_t addr) {
168     uint64_t val;
169     memcpy(&val, (void *)addr, sizeof(val));
170     return val;
171   }
172   double           getDouble(pint_t addr) {
173     double val;
174     memcpy(&val, (void *)addr, sizeof(val));
175     return val;
176   }
177   v128             getVector(pint_t addr) {
178     v128 val;
179     memcpy(&val, (void *)addr, sizeof(val));
180     return val;
181   }
182   uintptr_t       getP(pint_t addr);
183   uint64_t        getRegister(pint_t addr);
184   static uint64_t getULEB128(pint_t &addr, pint_t end);
185   static int64_t  getSLEB128(pint_t &addr, pint_t end);
186 
187   pint_t getEncodedP(pint_t &addr, pint_t end, uint8_t encoding,
188                      pint_t datarelBase = 0);
189   bool findFunctionName(pint_t addr, char *buf, size_t bufLen,
190                         unw_word_t *offset);
191   bool findUnwindSections(pint_t targetAddr, UnwindInfoSections &info);
192   bool findOtherFDE(pint_t targetAddr, pint_t &fde);
193 
194   static LocalAddressSpace sThisAddressSpace;
195 };
196 
197 inline uintptr_t LocalAddressSpace::getP(pint_t addr) {
198 #if __SIZEOF_POINTER__ == 8
199   return get64(addr);
200 #else
201   return get32(addr);
202 #endif
203 }
204 
205 inline uint64_t LocalAddressSpace::getRegister(pint_t addr) {
206 #if __SIZEOF_POINTER__ == 8 || defined(__mips64)
207   return get64(addr);
208 #else
209   return get32(addr);
210 #endif
211 }
212 
213 /// Read a ULEB128 into a 64-bit word.
214 inline uint64_t LocalAddressSpace::getULEB128(pint_t &addr, pint_t end) {
215   const uint8_t *p = (uint8_t *)addr;
216   const uint8_t *pend = (uint8_t *)end;
217   uint64_t result = 0;
218   int bit = 0;
219   do {
220     uint64_t b;
221 
222     if (p == pend)
223       _LIBUNWIND_ABORT("truncated uleb128 expression");
224 
225     b = *p & 0x7f;
226 
227     if (bit >= 64 || b << bit >> bit != b) {
228       _LIBUNWIND_ABORT("malformed uleb128 expression");
229     } else {
230       result |= b << bit;
231       bit += 7;
232     }
233   } while (*p++ >= 0x80);
234   addr = (pint_t) p;
235   return result;
236 }
237 
238 /// Read a SLEB128 into a 64-bit word.
239 inline int64_t LocalAddressSpace::getSLEB128(pint_t &addr, pint_t end) {
240   const uint8_t *p = (uint8_t *)addr;
241   const uint8_t *pend = (uint8_t *)end;
242   int64_t result = 0;
243   int bit = 0;
244   uint8_t byte;
245   do {
246     if (p == pend)
247       _LIBUNWIND_ABORT("truncated sleb128 expression");
248     byte = *p++;
249     result |= (uint64_t)(byte & 0x7f) << bit;
250     bit += 7;
251   } while (byte & 0x80);
252   // sign extend negative numbers
253   if ((byte & 0x40) != 0 && bit < 64)
254     result |= (-1ULL) << bit;
255   addr = (pint_t) p;
256   return result;
257 }
258 
259 inline LocalAddressSpace::pint_t
260 LocalAddressSpace::getEncodedP(pint_t &addr, pint_t end, uint8_t encoding,
261                                pint_t datarelBase) {
262   pint_t startAddr = addr;
263   const uint8_t *p = (uint8_t *)addr;
264   pint_t result;
265 
266   // first get value
267   switch (encoding & 0x0F) {
268   case DW_EH_PE_ptr:
269     result = getP(addr);
270     p += sizeof(pint_t);
271     addr = (pint_t) p;
272     break;
273   case DW_EH_PE_uleb128:
274     result = (pint_t)getULEB128(addr, end);
275     break;
276   case DW_EH_PE_udata2:
277     result = get16(addr);
278     p += 2;
279     addr = (pint_t) p;
280     break;
281   case DW_EH_PE_udata4:
282     result = get32(addr);
283     p += 4;
284     addr = (pint_t) p;
285     break;
286   case DW_EH_PE_udata8:
287     result = (pint_t)get64(addr);
288     p += 8;
289     addr = (pint_t) p;
290     break;
291   case DW_EH_PE_sleb128:
292     result = (pint_t)getSLEB128(addr, end);
293     break;
294   case DW_EH_PE_sdata2:
295     // Sign extend from signed 16-bit value.
296     result = (pint_t)(int16_t)get16(addr);
297     p += 2;
298     addr = (pint_t) p;
299     break;
300   case DW_EH_PE_sdata4:
301     // Sign extend from signed 32-bit value.
302     result = (pint_t)(int32_t)get32(addr);
303     p += 4;
304     addr = (pint_t) p;
305     break;
306   case DW_EH_PE_sdata8:
307     result = (pint_t)get64(addr);
308     p += 8;
309     addr = (pint_t) p;
310     break;
311   default:
312     _LIBUNWIND_ABORT("unknown pointer encoding");
313   }
314 
315   // then add relative offset
316   switch (encoding & 0x70) {
317   case DW_EH_PE_absptr:
318     // do nothing
319     break;
320   case DW_EH_PE_pcrel:
321     result += startAddr;
322     break;
323   case DW_EH_PE_textrel:
324     _LIBUNWIND_ABORT("DW_EH_PE_textrel pointer encoding not supported");
325     break;
326   case DW_EH_PE_datarel:
327     // DW_EH_PE_datarel is only valid in a few places, so the parameter has a
328     // default value of 0, and we abort in the event that someone calls this
329     // function with a datarelBase of 0 and DW_EH_PE_datarel encoding.
330     if (datarelBase == 0)
331       _LIBUNWIND_ABORT("DW_EH_PE_datarel is invalid with a datarelBase of 0");
332     result += datarelBase;
333     break;
334   case DW_EH_PE_funcrel:
335     _LIBUNWIND_ABORT("DW_EH_PE_funcrel pointer encoding not supported");
336     break;
337   case DW_EH_PE_aligned:
338     _LIBUNWIND_ABORT("DW_EH_PE_aligned pointer encoding not supported");
339     break;
340   default:
341     _LIBUNWIND_ABORT("unknown pointer encoding");
342     break;
343   }
344 
345   if (encoding & DW_EH_PE_indirect)
346     result = getP(result);
347 
348   return result;
349 }
350 
351 #if defined(_LIBUNWIND_USE_DL_ITERATE_PHDR)
352 
353 // The ElfW() macro for pointer-size independent ELF header traversal is not
354 // provided by <link.h> on some systems (e.g., FreeBSD). On these systems the
355 // data structures are just called Elf_XXX. Define ElfW() locally.
356 #if !defined(ElfW)
357   #define ElfW(type) Elf_##type
358 #endif
359 #if !defined(Elf_Half)
360   typedef ElfW(Half) Elf_Half;
361 #endif
362 #if !defined(Elf_Phdr)
363   typedef ElfW(Phdr) Elf_Phdr;
364 #endif
365 #if !defined(Elf_Addr)
366   typedef ElfW(Addr) Elf_Addr;
367 #endif
368 
369 static Elf_Addr calculateImageBase(struct dl_phdr_info *pinfo) {
370   Elf_Addr image_base = pinfo->dlpi_addr;
371 #if defined(__ANDROID__) && __ANDROID_API__ < 18
372   if (image_base == 0) {
373     // Normally, an image base of 0 indicates a non-PIE executable. On
374     // versions of Android prior to API 18, the dynamic linker reported a
375     // dlpi_addr of 0 for PIE executables. Compute the true image base
376     // using the PT_PHDR segment.
377     // See https://github.com/android/ndk/issues/505.
378     for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
379       const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
380       if (phdr->p_type == PT_PHDR) {
381         image_base = reinterpret_cast<Elf_Addr>(pinfo->dlpi_phdr) -
382           phdr->p_vaddr;
383         break;
384       }
385     }
386   }
387 #endif
388   return image_base;
389 }
390 
391 struct _LIBUNWIND_HIDDEN dl_iterate_cb_data {
392   LocalAddressSpace *addressSpace;
393   UnwindInfoSections *sects;
394   uintptr_t targetAddr;
395 };
396 
397 #if defined(_LIBUNWIND_USE_FRAME_HEADER_CACHE)
398 #include "FrameHeaderCache.hpp"
399 
400 // Typically there is one cache per process, but when libunwind is built as a
401 // hermetic static library, then each shared object may have its own cache.
402 static FrameHeaderCache TheFrameHeaderCache;
403 #endif
404 
405 static bool checkAddrInSegment(const Elf_Phdr *phdr, size_t image_base,
406                                dl_iterate_cb_data *cbdata) {
407   if (phdr->p_type == PT_LOAD) {
408     uintptr_t begin = image_base + phdr->p_vaddr;
409     uintptr_t end = begin + phdr->p_memsz;
410     if (cbdata->targetAddr >= begin && cbdata->targetAddr < end) {
411       cbdata->sects->dso_base = begin;
412       cbdata->sects->text_segment_length = phdr->p_memsz;
413       return true;
414     }
415   }
416   return false;
417 }
418 
419 static bool checkForUnwindInfoSegment(const Elf_Phdr *phdr, size_t image_base,
420                                       dl_iterate_cb_data *cbdata) {
421 #if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
422   if (phdr->p_type == PT_GNU_EH_FRAME) {
423     EHHeaderParser<LocalAddressSpace>::EHHeaderInfo hdrInfo;
424     uintptr_t eh_frame_hdr_start = image_base + phdr->p_vaddr;
425     cbdata->sects->dwarf_index_section = eh_frame_hdr_start;
426     cbdata->sects->dwarf_index_section_length = phdr->p_memsz;
427     if (EHHeaderParser<LocalAddressSpace>::decodeEHHdr(
428             *cbdata->addressSpace, eh_frame_hdr_start, phdr->p_memsz,
429             hdrInfo)) {
430       // .eh_frame_hdr records the start of .eh_frame, but not its size.
431       // Rely on a zero terminator to find the end of the section.
432       cbdata->sects->dwarf_section = hdrInfo.eh_frame_ptr;
433       cbdata->sects->dwarf_section_length = SIZE_MAX;
434       return true;
435     }
436   }
437   return false;
438 #elif defined(_LIBUNWIND_ARM_EHABI)
439   if (phdr->p_type == PT_ARM_EXIDX) {
440     uintptr_t exidx_start = image_base + phdr->p_vaddr;
441     cbdata->sects->arm_section = exidx_start;
442     cbdata->sects->arm_section_length = phdr->p_memsz;
443     return true;
444   }
445   return false;
446 #else
447 #error Need one of _LIBUNWIND_SUPPORT_DWARF_INDEX or _LIBUNWIND_ARM_EHABI
448 #endif
449 }
450 
451 static int findUnwindSectionsByPhdr(struct dl_phdr_info *pinfo,
452                                     size_t pinfo_size, void *data) {
453   auto cbdata = static_cast<dl_iterate_cb_data *>(data);
454   if (pinfo->dlpi_phnum == 0 || cbdata->targetAddr < pinfo->dlpi_addr)
455     return 0;
456 #if defined(_LIBUNWIND_USE_FRAME_HEADER_CACHE)
457   if (TheFrameHeaderCache.find(pinfo, pinfo_size, data))
458     return 1;
459 #else
460   // Avoid warning about unused variable.
461   (void)pinfo_size;
462 #endif
463 
464   Elf_Addr image_base = calculateImageBase(pinfo);
465 
466   // Most shared objects seen in this callback function likely don't contain the
467   // target address, so optimize for that. Scan for a matching PT_LOAD segment
468   // first and bail when it isn't found.
469   bool found_text = false;
470   for (Elf_Half i = 0; i < pinfo->dlpi_phnum; ++i) {
471     if (checkAddrInSegment(&pinfo->dlpi_phdr[i], image_base, cbdata)) {
472       found_text = true;
473       break;
474     }
475   }
476   if (!found_text)
477     return 0;
478 
479   // PT_GNU_EH_FRAME and PT_ARM_EXIDX are usually near the end. Iterate
480   // backward.
481   bool found_unwind = false;
482   for (Elf_Half i = pinfo->dlpi_phnum; i > 0; i--) {
483     const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i - 1];
484     if (checkForUnwindInfoSegment(phdr, image_base, cbdata)) {
485       found_unwind = true;
486       break;
487     }
488   }
489   if (!found_unwind)
490     return 0;
491 
492 #if defined(_LIBUNWIND_USE_FRAME_HEADER_CACHE)
493   TheFrameHeaderCache.add(cbdata->sects);
494 #endif
495   return 1;
496 }
497 
498 #endif  // defined(_LIBUNWIND_USE_DL_ITERATE_PHDR)
499 
500 
501 inline bool LocalAddressSpace::findUnwindSections(pint_t targetAddr,
502                                                   UnwindInfoSections &info) {
503 #ifdef __APPLE__
504   dyld_unwind_sections dyldInfo;
505   if (_dyld_find_unwind_sections((void *)targetAddr, &dyldInfo)) {
506     info.dso_base                      = (uintptr_t)dyldInfo.mh;
507  #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
508     info.dwarf_section                 = (uintptr_t)dyldInfo.dwarf_section;
509     info.dwarf_section_length          = (size_t)dyldInfo.dwarf_section_length;
510  #endif
511     info.compact_unwind_section        = (uintptr_t)dyldInfo.compact_unwind_section;
512     info.compact_unwind_section_length = (size_t)dyldInfo.compact_unwind_section_length;
513     return true;
514   }
515 #elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_LIBUNWIND_IS_BAREMETAL)
516   info.dso_base = 0;
517   // Bare metal is statically linked, so no need to ask the dynamic loader
518   info.dwarf_section_length = (size_t)(&__eh_frame_end - &__eh_frame_start);
519   info.dwarf_section =        (uintptr_t)(&__eh_frame_start);
520   _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: section %p length %p",
521                              (void *)info.dwarf_section, (void *)info.dwarf_section_length);
522 #if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
523   info.dwarf_index_section =        (uintptr_t)(&__eh_frame_hdr_start);
524   info.dwarf_index_section_length = (size_t)(&__eh_frame_hdr_end - &__eh_frame_hdr_start);
525   _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: index section %p length %p",
526                              (void *)info.dwarf_index_section, (void *)info.dwarf_index_section_length);
527 #endif
528   if (info.dwarf_section_length)
529     return true;
530 #elif defined(_LIBUNWIND_ARM_EHABI) && defined(_LIBUNWIND_IS_BAREMETAL)
531   // Bare metal is statically linked, so no need to ask the dynamic loader
532   info.arm_section =        (uintptr_t)(&__exidx_start);
533   info.arm_section_length = (size_t)(&__exidx_end - &__exidx_start);
534   _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: section %p length %p",
535                              (void *)info.arm_section, (void *)info.arm_section_length);
536   if (info.arm_section && info.arm_section_length)
537     return true;
538 #elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_WIN32)
539   HMODULE mods[1024];
540   HANDLE process = GetCurrentProcess();
541   DWORD needed;
542 
543   if (!EnumProcessModules(process, mods, sizeof(mods), &needed)) {
544     DWORD err = GetLastError();
545     _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: EnumProcessModules failed, "
546                                "returned error %d", (int)err);
547     return false;
548   }
549 
550   for (unsigned i = 0; i < (needed / sizeof(HMODULE)); i++) {
551     PIMAGE_DOS_HEADER pidh = (PIMAGE_DOS_HEADER)mods[i];
552     PIMAGE_NT_HEADERS pinh = (PIMAGE_NT_HEADERS)((BYTE *)pidh + pidh->e_lfanew);
553     PIMAGE_FILE_HEADER pifh = (PIMAGE_FILE_HEADER)&pinh->FileHeader;
554     PIMAGE_SECTION_HEADER pish = IMAGE_FIRST_SECTION(pinh);
555     bool found_obj = false;
556     bool found_hdr = false;
557 
558     info.dso_base = (uintptr_t)mods[i];
559     for (unsigned j = 0; j < pifh->NumberOfSections; j++, pish++) {
560       uintptr_t begin = pish->VirtualAddress + (uintptr_t)mods[i];
561       uintptr_t end = begin + pish->Misc.VirtualSize;
562       if (!strncmp((const char *)pish->Name, ".text",
563                    IMAGE_SIZEOF_SHORT_NAME)) {
564         if (targetAddr >= begin && targetAddr < end)
565           found_obj = true;
566       } else if (!strncmp((const char *)pish->Name, ".eh_frame",
567                           IMAGE_SIZEOF_SHORT_NAME)) {
568         info.dwarf_section = begin;
569         info.dwarf_section_length = pish->Misc.VirtualSize;
570         found_hdr = true;
571       }
572       if (found_obj && found_hdr)
573         return true;
574     }
575   }
576   return false;
577 #elif defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)
578   // Don't even bother, since Windows has functions that do all this stuff
579   // for us.
580   (void)targetAddr;
581   (void)info;
582   return true;
583 #elif defined(_LIBUNWIND_USE_DL_UNWIND_FIND_EXIDX)
584   int length = 0;
585   info.arm_section =
586       (uintptr_t)dl_unwind_find_exidx((_Unwind_Ptr)targetAddr, &length);
587   info.arm_section_length = (size_t)length * sizeof(EHABIIndexEntry);
588   if (info.arm_section && info.arm_section_length)
589     return true;
590 #elif defined(_LIBUNWIND_USE_DL_ITERATE_PHDR)
591   dl_iterate_cb_data cb_data = {this, &info, targetAddr};
592   int found = dl_iterate_phdr(findUnwindSectionsByPhdr, &cb_data);
593   return static_cast<bool>(found);
594 #endif
595 
596   return false;
597 }
598 
599 
600 inline bool LocalAddressSpace::findOtherFDE(pint_t targetAddr, pint_t &fde) {
601   // TO DO: if OS has way to dynamically register FDEs, check that.
602   (void)targetAddr;
603   (void)fde;
604   return false;
605 }
606 
607 inline bool LocalAddressSpace::findFunctionName(pint_t addr, char *buf,
608                                                 size_t bufLen,
609                                                 unw_word_t *offset) {
610 #if _LIBUNWIND_USE_DLADDR
611   Dl_info dyldInfo;
612   if (dladdr((void *)addr, &dyldInfo)) {
613     if (dyldInfo.dli_sname != NULL) {
614       snprintf(buf, bufLen, "%s", dyldInfo.dli_sname);
615       *offset = (addr - (pint_t) dyldInfo.dli_saddr);
616       return true;
617     }
618   }
619 #else
620   (void)addr;
621   (void)buf;
622   (void)bufLen;
623   (void)offset;
624 #endif
625   return false;
626 }
627 
628 } // namespace libunwind
629 
630 #endif // __ADDRESSSPACE_HPP__
631