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 // Implements unw_* functions from <libunwind.h>
9 //
10 //===----------------------------------------------------------------------===//
11
12 #include <libunwind.h>
13
14 #include "config.h"
15 #include "libunwind_ext.h"
16
17 #include <stdlib.h>
18
19 // Define the __has_feature extension for compilers that do not support it so
20 // that we can later check for the presence of ASan in a compiler-neutral way.
21 #if !defined(__has_feature)
22 #define __has_feature(feature) 0
23 #endif
24
25 #if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
26 #include <sanitizer/asan_interface.h>
27 #endif
28
29 #if !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__USING_WASM_EXCEPTIONS__)
30 #include "AddressSpace.hpp"
31 #include "UnwindCursor.hpp"
32
33 using namespace libunwind;
34
35 /// internal object to represent this processes address space
36 LocalAddressSpace LocalAddressSpace::sThisAddressSpace;
37
38 _LIBUNWIND_EXPORT unw_addr_space_t unw_local_addr_space =
39 (unw_addr_space_t)&LocalAddressSpace::sThisAddressSpace;
40
41 /// Create a cursor of a thread in this process given 'context' recorded by
42 /// __unw_getcontext().
__unw_init_local(unw_cursor_t * cursor,unw_context_t * context)43 _LIBUNWIND_HIDDEN int __unw_init_local(unw_cursor_t *cursor,
44 unw_context_t *context) {
45 _LIBUNWIND_TRACE_API("__unw_init_local(cursor=%p, context=%p)",
46 static_cast<void *>(cursor),
47 static_cast<void *>(context));
48 #if defined(__i386__)
49 # define REGISTER_KIND Registers_x86
50 #elif defined(__x86_64__)
51 # define REGISTER_KIND Registers_x86_64
52 #elif defined(__powerpc64__)
53 # define REGISTER_KIND Registers_ppc64
54 #elif defined(__powerpc__)
55 # define REGISTER_KIND Registers_ppc
56 #elif defined(__aarch64__)
57 # define REGISTER_KIND Registers_arm64
58 #elif defined(__arm__)
59 # define REGISTER_KIND Registers_arm
60 #elif defined(__or1k__)
61 # define REGISTER_KIND Registers_or1k
62 #elif defined(__hexagon__)
63 # define REGISTER_KIND Registers_hexagon
64 #elif defined(__mips__) && defined(_ABIO32) && _MIPS_SIM == _ABIO32
65 # define REGISTER_KIND Registers_mips_o32
66 #elif defined(__mips64)
67 # define REGISTER_KIND Registers_mips_newabi
68 #elif defined(__mips__)
69 # warning The MIPS architecture is not supported with this ABI and environment!
70 #elif defined(__sparc__) && defined(__arch64__)
71 #define REGISTER_KIND Registers_sparc64
72 #elif defined(__sparc__)
73 # define REGISTER_KIND Registers_sparc
74 #elif defined(__riscv)
75 # define REGISTER_KIND Registers_riscv
76 #elif defined(__ve__)
77 # define REGISTER_KIND Registers_ve
78 #elif defined(__s390x__)
79 # define REGISTER_KIND Registers_s390x
80 #elif defined(__loongarch__) && __loongarch_grlen == 64
81 #define REGISTER_KIND Registers_loongarch
82 #else
83 # error Architecture not supported
84 #endif
85 // Use "placement new" to allocate UnwindCursor in the cursor buffer.
86 new (reinterpret_cast<UnwindCursor<LocalAddressSpace, REGISTER_KIND> *>(cursor))
87 UnwindCursor<LocalAddressSpace, REGISTER_KIND>(
88 context, LocalAddressSpace::sThisAddressSpace);
89 #undef REGISTER_KIND
90 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
91 co->setInfoBasedOnIPRegister();
92
93 return UNW_ESUCCESS;
94 }
_LIBUNWIND_WEAK_ALIAS(__unw_init_local,unw_init_local)95 _LIBUNWIND_WEAK_ALIAS(__unw_init_local, unw_init_local)
96
97 /// Get value of specified register at cursor position in stack frame.
98 _LIBUNWIND_HIDDEN int __unw_get_reg(unw_cursor_t *cursor, unw_regnum_t regNum,
99 unw_word_t *value) {
100 _LIBUNWIND_TRACE_API("__unw_get_reg(cursor=%p, regNum=%d, &value=%p)",
101 static_cast<void *>(cursor), regNum,
102 static_cast<void *>(value));
103 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
104 if (co->validReg(regNum)) {
105 *value = co->getReg(regNum);
106 return UNW_ESUCCESS;
107 }
108 return UNW_EBADREG;
109 }
_LIBUNWIND_WEAK_ALIAS(__unw_get_reg,unw_get_reg)110 _LIBUNWIND_WEAK_ALIAS(__unw_get_reg, unw_get_reg)
111
112 /// Set value of specified register at cursor position in stack frame.
113 _LIBUNWIND_HIDDEN int __unw_set_reg(unw_cursor_t *cursor, unw_regnum_t regNum,
114 unw_word_t value) {
115 _LIBUNWIND_TRACE_API("__unw_set_reg(cursor=%p, regNum=%d, value=0x%" PRIxPTR
116 ")",
117 static_cast<void *>(cursor), regNum, value);
118 typedef LocalAddressSpace::pint_t pint_t;
119 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
120 if (co->validReg(regNum)) {
121 co->setReg(regNum, (pint_t)value);
122 // special case altering IP to re-find info (being called by personality
123 // function)
124 if (regNum == UNW_REG_IP) {
125 unw_proc_info_t info;
126 // First, get the FDE for the old location and then update it.
127 co->getInfo(&info);
128 co->setInfoBasedOnIPRegister(false);
129 // If the original call expects stack adjustment, perform this now.
130 // Normal frame unwinding would have included the offset already in the
131 // CFA computation.
132 // Note: for PA-RISC and other platforms where the stack grows up,
133 // this should actually be - info.gp. LLVM doesn't currently support
134 // any such platforms and Clang doesn't export a macro for them.
135 if (info.gp)
136 co->setReg(UNW_REG_SP, co->getReg(UNW_REG_SP) + info.gp);
137 }
138 return UNW_ESUCCESS;
139 }
140 return UNW_EBADREG;
141 }
_LIBUNWIND_WEAK_ALIAS(__unw_set_reg,unw_set_reg)142 _LIBUNWIND_WEAK_ALIAS(__unw_set_reg, unw_set_reg)
143
144 /// Get value of specified float register at cursor position in stack frame.
145 _LIBUNWIND_HIDDEN int __unw_get_fpreg(unw_cursor_t *cursor, unw_regnum_t regNum,
146 unw_fpreg_t *value) {
147 _LIBUNWIND_TRACE_API("__unw_get_fpreg(cursor=%p, regNum=%d, &value=%p)",
148 static_cast<void *>(cursor), regNum,
149 static_cast<void *>(value));
150 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
151 if (co->validFloatReg(regNum)) {
152 *value = co->getFloatReg(regNum);
153 return UNW_ESUCCESS;
154 }
155 return UNW_EBADREG;
156 }
_LIBUNWIND_WEAK_ALIAS(__unw_get_fpreg,unw_get_fpreg)157 _LIBUNWIND_WEAK_ALIAS(__unw_get_fpreg, unw_get_fpreg)
158
159 /// Set value of specified float register at cursor position in stack frame.
160 _LIBUNWIND_HIDDEN int __unw_set_fpreg(unw_cursor_t *cursor, unw_regnum_t regNum,
161 unw_fpreg_t value) {
162 #if defined(_LIBUNWIND_ARM_EHABI)
163 _LIBUNWIND_TRACE_API("__unw_set_fpreg(cursor=%p, regNum=%d, value=%llX)",
164 static_cast<void *>(cursor), regNum, value);
165 #else
166 _LIBUNWIND_TRACE_API("__unw_set_fpreg(cursor=%p, regNum=%d, value=%g)",
167 static_cast<void *>(cursor), regNum, value);
168 #endif
169 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
170 if (co->validFloatReg(regNum)) {
171 co->setFloatReg(regNum, value);
172 return UNW_ESUCCESS;
173 }
174 return UNW_EBADREG;
175 }
_LIBUNWIND_WEAK_ALIAS(__unw_set_fpreg,unw_set_fpreg)176 _LIBUNWIND_WEAK_ALIAS(__unw_set_fpreg, unw_set_fpreg)
177
178 /// Move cursor to next frame.
179 _LIBUNWIND_HIDDEN int __unw_step(unw_cursor_t *cursor) {
180 _LIBUNWIND_TRACE_API("__unw_step(cursor=%p)", static_cast<void *>(cursor));
181 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
182 return co->step();
183 }
_LIBUNWIND_WEAK_ALIAS(__unw_step,unw_step)184 _LIBUNWIND_WEAK_ALIAS(__unw_step, unw_step)
185
186 // Move cursor to next frame and for stage2 of unwinding.
187 // This resets MTE tags of tagged frames to zero.
188 extern "C" _LIBUNWIND_HIDDEN int __unw_step_stage2(unw_cursor_t *cursor) {
189 _LIBUNWIND_TRACE_API("__unw_step_stage2(cursor=%p)",
190 static_cast<void *>(cursor));
191 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
192 return co->step(true);
193 }
194
195 /// Get unwind info at cursor position in stack frame.
__unw_get_proc_info(unw_cursor_t * cursor,unw_proc_info_t * info)196 _LIBUNWIND_HIDDEN int __unw_get_proc_info(unw_cursor_t *cursor,
197 unw_proc_info_t *info) {
198 _LIBUNWIND_TRACE_API("__unw_get_proc_info(cursor=%p, &info=%p)",
199 static_cast<void *>(cursor), static_cast<void *>(info));
200 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
201 co->getInfo(info);
202 if (info->end_ip == 0)
203 return UNW_ENOINFO;
204 return UNW_ESUCCESS;
205 }
_LIBUNWIND_WEAK_ALIAS(__unw_get_proc_info,unw_get_proc_info)206 _LIBUNWIND_WEAK_ALIAS(__unw_get_proc_info, unw_get_proc_info)
207
208 /// Resume execution at cursor position (aka longjump).
209 _LIBUNWIND_HIDDEN int __unw_resume(unw_cursor_t *cursor) {
210 _LIBUNWIND_TRACE_API("__unw_resume(cursor=%p)", static_cast<void *>(cursor));
211 #if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
212 // Inform the ASan runtime that now might be a good time to clean stuff up.
213 __asan_handle_no_return();
214 #endif
215 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
216 co->jumpto();
217 return UNW_EUNSPEC;
218 }
_LIBUNWIND_WEAK_ALIAS(__unw_resume,unw_resume)219 _LIBUNWIND_WEAK_ALIAS(__unw_resume, unw_resume)
220
221 /// Get name of function at cursor position in stack frame.
222 _LIBUNWIND_HIDDEN int __unw_get_proc_name(unw_cursor_t *cursor, char *buf,
223 size_t bufLen, unw_word_t *offset) {
224 _LIBUNWIND_TRACE_API("__unw_get_proc_name(cursor=%p, &buf=%p, bufLen=%lu)",
225 static_cast<void *>(cursor), static_cast<void *>(buf),
226 static_cast<unsigned long>(bufLen));
227 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
228 if (co->getFunctionName(buf, bufLen, offset))
229 return UNW_ESUCCESS;
230 return UNW_EUNSPEC;
231 }
_LIBUNWIND_WEAK_ALIAS(__unw_get_proc_name,unw_get_proc_name)232 _LIBUNWIND_WEAK_ALIAS(__unw_get_proc_name, unw_get_proc_name)
233
234 /// Checks if a register is a floating-point register.
235 _LIBUNWIND_HIDDEN int __unw_is_fpreg(unw_cursor_t *cursor,
236 unw_regnum_t regNum) {
237 _LIBUNWIND_TRACE_API("__unw_is_fpreg(cursor=%p, regNum=%d)",
238 static_cast<void *>(cursor), regNum);
239 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
240 return co->validFloatReg(regNum);
241 }
_LIBUNWIND_WEAK_ALIAS(__unw_is_fpreg,unw_is_fpreg)242 _LIBUNWIND_WEAK_ALIAS(__unw_is_fpreg, unw_is_fpreg)
243
244 /// Checks if a register is a floating-point register.
245 _LIBUNWIND_HIDDEN const char *__unw_regname(unw_cursor_t *cursor,
246 unw_regnum_t regNum) {
247 _LIBUNWIND_TRACE_API("__unw_regname(cursor=%p, regNum=%d)",
248 static_cast<void *>(cursor), regNum);
249 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
250 return co->getRegisterName(regNum);
251 }
_LIBUNWIND_WEAK_ALIAS(__unw_regname,unw_regname)252 _LIBUNWIND_WEAK_ALIAS(__unw_regname, unw_regname)
253
254 /// Checks if current frame is signal trampoline.
255 _LIBUNWIND_HIDDEN int __unw_is_signal_frame(unw_cursor_t *cursor) {
256 _LIBUNWIND_TRACE_API("__unw_is_signal_frame(cursor=%p)",
257 static_cast<void *>(cursor));
258 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
259 return co->isSignalFrame();
260 }
_LIBUNWIND_WEAK_ALIAS(__unw_is_signal_frame,unw_is_signal_frame)261 _LIBUNWIND_WEAK_ALIAS(__unw_is_signal_frame, unw_is_signal_frame)
262
263 #ifdef _AIX
264 _LIBUNWIND_EXPORT uintptr_t __unw_get_data_rel_base(unw_cursor_t *cursor) {
265 _LIBUNWIND_TRACE_API("unw_get_data_rel_base(cursor=%p)",
266 static_cast<void *>(cursor));
267 AbstractUnwindCursor *co = reinterpret_cast<AbstractUnwindCursor *>(cursor);
268 return co->getDataRelBase();
269 }
_LIBUNWIND_WEAK_ALIAS(__unw_get_data_rel_base,unw_get_data_rel_base)270 _LIBUNWIND_WEAK_ALIAS(__unw_get_data_rel_base, unw_get_data_rel_base)
271 #endif
272
273 #ifdef __arm__
274 // Save VFP registers d0-d15 using FSTMIADX instead of FSTMIADD
275 _LIBUNWIND_HIDDEN void __unw_save_vfp_as_X(unw_cursor_t *cursor) {
276 _LIBUNWIND_TRACE_API("__unw_get_fpreg_save_vfp_as_X(cursor=%p)",
277 static_cast<void *>(cursor));
278 AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
279 return co->saveVFPAsX();
280 }
_LIBUNWIND_WEAK_ALIAS(__unw_save_vfp_as_X,unw_save_vfp_as_X)281 _LIBUNWIND_WEAK_ALIAS(__unw_save_vfp_as_X, unw_save_vfp_as_X)
282 #endif
283
284
285 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
286 /// SPI: walks cached DWARF entries
287 _LIBUNWIND_HIDDEN void __unw_iterate_dwarf_unwind_cache(void (*func)(
288 unw_word_t ip_start, unw_word_t ip_end, unw_word_t fde, unw_word_t mh)) {
289 _LIBUNWIND_TRACE_API("__unw_iterate_dwarf_unwind_cache(func=%p)",
290 reinterpret_cast<void *>(func));
291 DwarfFDECache<LocalAddressSpace>::iterateCacheEntries(func);
292 }
_LIBUNWIND_WEAK_ALIAS(__unw_iterate_dwarf_unwind_cache,unw_iterate_dwarf_unwind_cache)293 _LIBUNWIND_WEAK_ALIAS(__unw_iterate_dwarf_unwind_cache,
294 unw_iterate_dwarf_unwind_cache)
295
296 /// IPI: for __register_frame()
297 void __unw_add_dynamic_fde(unw_word_t fde) {
298 CFI_Parser<LocalAddressSpace>::FDE_Info fdeInfo;
299 CFI_Parser<LocalAddressSpace>::CIE_Info cieInfo;
300 const char *message = CFI_Parser<LocalAddressSpace>::decodeFDE(
301 LocalAddressSpace::sThisAddressSpace,
302 (LocalAddressSpace::pint_t) fde, &fdeInfo, &cieInfo);
303 if (message == NULL) {
304 // dynamically registered FDEs don't have a mach_header group they are in.
305 // Use fde as mh_group
306 unw_word_t mh_group = fdeInfo.fdeStart;
307 DwarfFDECache<LocalAddressSpace>::add((LocalAddressSpace::pint_t)mh_group,
308 fdeInfo.pcStart, fdeInfo.pcEnd,
309 fdeInfo.fdeStart);
310 } else {
311 _LIBUNWIND_DEBUG_LOG("__unw_add_dynamic_fde: bad fde: %s", message);
312 }
313 }
314
315 /// IPI: for __deregister_frame()
__unw_remove_dynamic_fde(unw_word_t fde)316 void __unw_remove_dynamic_fde(unw_word_t fde) {
317 // fde is own mh_group
318 DwarfFDECache<LocalAddressSpace>::removeAllIn((LocalAddressSpace::pint_t)fde);
319 }
320
__unw_add_dynamic_eh_frame_section(unw_word_t eh_frame_start)321 void __unw_add_dynamic_eh_frame_section(unw_word_t eh_frame_start) {
322 // The eh_frame section start serves as the mh_group
323 unw_word_t mh_group = eh_frame_start;
324 CFI_Parser<LocalAddressSpace>::CIE_Info cieInfo;
325 CFI_Parser<LocalAddressSpace>::FDE_Info fdeInfo;
326 auto p = (LocalAddressSpace::pint_t)eh_frame_start;
327 while (LocalAddressSpace::sThisAddressSpace.get32(p)) {
328 if (CFI_Parser<LocalAddressSpace>::decodeFDE(
329 LocalAddressSpace::sThisAddressSpace, p, &fdeInfo, &cieInfo,
330 true) == NULL) {
331 DwarfFDECache<LocalAddressSpace>::add((LocalAddressSpace::pint_t)mh_group,
332 fdeInfo.pcStart, fdeInfo.pcEnd,
333 fdeInfo.fdeStart);
334 p += fdeInfo.fdeLength;
335 } else if (CFI_Parser<LocalAddressSpace>::parseCIE(
336 LocalAddressSpace::sThisAddressSpace, p, &cieInfo) == NULL) {
337 p += cieInfo.cieLength;
338 } else
339 return;
340 }
341 }
342
__unw_remove_dynamic_eh_frame_section(unw_word_t eh_frame_start)343 void __unw_remove_dynamic_eh_frame_section(unw_word_t eh_frame_start) {
344 // The eh_frame section start serves as the mh_group
345 DwarfFDECache<LocalAddressSpace>::removeAllIn(
346 (LocalAddressSpace::pint_t)eh_frame_start);
347 }
348
349 #endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
350 #endif // !defined(__USING_SJLJ_EXCEPTIONS__) &&
351 // !defined(__USING_WASM_EXCEPTIONS__)
352
353 #ifdef __APPLE__
354
355 namespace libunwind {
356
357 static constexpr size_t MAX_DYNAMIC_UNWIND_SECTIONS_FINDERS = 8;
358
359 static RWMutex findDynamicUnwindSectionsLock;
360 static size_t numDynamicUnwindSectionsFinders = 0;
361 static unw_find_dynamic_unwind_sections
362 dynamicUnwindSectionsFinders[MAX_DYNAMIC_UNWIND_SECTIONS_FINDERS] = {0};
363
findDynamicUnwindSections(void * addr,unw_dynamic_unwind_sections * info)364 bool findDynamicUnwindSections(void *addr, unw_dynamic_unwind_sections *info) {
365 bool found = false;
366 findDynamicUnwindSectionsLock.lock_shared();
367 for (size_t i = 0; i != numDynamicUnwindSectionsFinders; ++i) {
368 if (dynamicUnwindSectionsFinders[i]((unw_word_t)addr, info)) {
369 found = true;
370 break;
371 }
372 }
373 findDynamicUnwindSectionsLock.unlock_shared();
374 return found;
375 }
376
377 } // namespace libunwind
378
__unw_add_find_dynamic_unwind_sections(unw_find_dynamic_unwind_sections find_dynamic_unwind_sections)379 int __unw_add_find_dynamic_unwind_sections(
380 unw_find_dynamic_unwind_sections find_dynamic_unwind_sections) {
381 findDynamicUnwindSectionsLock.lock();
382
383 // Check that we have enough space...
384 if (numDynamicUnwindSectionsFinders == MAX_DYNAMIC_UNWIND_SECTIONS_FINDERS) {
385 findDynamicUnwindSectionsLock.unlock();
386 return UNW_ENOMEM;
387 }
388
389 // Check for value already present...
390 for (size_t i = 0; i != numDynamicUnwindSectionsFinders; ++i) {
391 if (dynamicUnwindSectionsFinders[i] == find_dynamic_unwind_sections) {
392 findDynamicUnwindSectionsLock.unlock();
393 return UNW_EINVAL;
394 }
395 }
396
397 // Success -- add callback entry.
398 dynamicUnwindSectionsFinders[numDynamicUnwindSectionsFinders++] =
399 find_dynamic_unwind_sections;
400 findDynamicUnwindSectionsLock.unlock();
401
402 return UNW_ESUCCESS;
403 }
404
__unw_remove_find_dynamic_unwind_sections(unw_find_dynamic_unwind_sections find_dynamic_unwind_sections)405 int __unw_remove_find_dynamic_unwind_sections(
406 unw_find_dynamic_unwind_sections find_dynamic_unwind_sections) {
407 findDynamicUnwindSectionsLock.lock();
408
409 // Find index to remove.
410 size_t finderIdx = numDynamicUnwindSectionsFinders;
411 for (size_t i = 0; i != numDynamicUnwindSectionsFinders; ++i) {
412 if (dynamicUnwindSectionsFinders[i] == find_dynamic_unwind_sections) {
413 finderIdx = i;
414 break;
415 }
416 }
417
418 // If no such registration is present then error out.
419 if (finderIdx == numDynamicUnwindSectionsFinders) {
420 findDynamicUnwindSectionsLock.unlock();
421 return UNW_EINVAL;
422 }
423
424 // Remove entry.
425 for (size_t i = finderIdx; i != numDynamicUnwindSectionsFinders - 1; ++i)
426 dynamicUnwindSectionsFinders[i] = dynamicUnwindSectionsFinders[i + 1];
427 dynamicUnwindSectionsFinders[--numDynamicUnwindSectionsFinders] = nullptr;
428
429 findDynamicUnwindSectionsLock.unlock();
430 return UNW_ESUCCESS;
431 }
432
433 #endif // __APPLE__
434
435 // Add logging hooks in Debug builds only
436 #ifndef NDEBUG
437 #include <stdlib.h>
438
439 _LIBUNWIND_HIDDEN
logAPIs()440 bool logAPIs() {
441 // do manual lock to avoid use of _cxa_guard_acquire or initializers
442 static bool checked = false;
443 static bool log = false;
444 if (!checked) {
445 log = (getenv("LIBUNWIND_PRINT_APIS") != NULL);
446 checked = true;
447 }
448 return log;
449 }
450
451 _LIBUNWIND_HIDDEN
logUnwinding()452 bool logUnwinding() {
453 // do manual lock to avoid use of _cxa_guard_acquire or initializers
454 static bool checked = false;
455 static bool log = false;
456 if (!checked) {
457 log = (getenv("LIBUNWIND_PRINT_UNWINDING") != NULL);
458 checked = true;
459 }
460 return log;
461 }
462
463 _LIBUNWIND_HIDDEN
logDWARF()464 bool logDWARF() {
465 // do manual lock to avoid use of _cxa_guard_acquire or initializers
466 static bool checked = false;
467 static bool log = false;
468 if (!checked) {
469 log = (getenv("LIBUNWIND_PRINT_DWARF") != NULL);
470 checked = true;
471 }
472 return log;
473 }
474
475 #endif // NDEBUG
476
477