xref: /llvm-project/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp (revision 9894cd5febbb89ad5b97c006179aaee77b824f91)
1 //===-- ThreadElfCore.cpp -------------------------------------------------===//
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 
9 #include "lldb/Target/RegisterContext.h"
10 #include "lldb/Target/StopInfo.h"
11 #include "lldb/Target/Target.h"
12 #include "lldb/Target/UnixSignals.h"
13 #include "lldb/Target/Unwind.h"
14 #include "lldb/Utility/DataExtractor.h"
15 #include "lldb/Utility/LLDBLog.h"
16 #include "lldb/Utility/Log.h"
17 #include "lldb/Utility/ProcessInfo.h"
18 
19 #include "Plugins/Process/Utility/RegisterContextFreeBSD_i386.h"
20 #include "Plugins/Process/Utility/RegisterContextFreeBSD_mips64.h"
21 #include "Plugins/Process/Utility/RegisterContextFreeBSD_powerpc.h"
22 #include "Plugins/Process/Utility/RegisterContextFreeBSD_x86_64.h"
23 #include "Plugins/Process/Utility/RegisterContextLinux_i386.h"
24 #include "Plugins/Process/Utility/RegisterContextLinux_s390x.h"
25 #include "Plugins/Process/Utility/RegisterContextLinux_x86_64.h"
26 #include "Plugins/Process/Utility/RegisterContextNetBSD_i386.h"
27 #include "Plugins/Process/Utility/RegisterContextNetBSD_x86_64.h"
28 #include "Plugins/Process/Utility/RegisterContextOpenBSD_i386.h"
29 #include "Plugins/Process/Utility/RegisterContextOpenBSD_x86_64.h"
30 #include "Plugins/Process/Utility/RegisterInfoPOSIX_arm.h"
31 #include "Plugins/Process/Utility/RegisterInfoPOSIX_arm64.h"
32 #include "Plugins/Process/Utility/RegisterInfoPOSIX_ppc64le.h"
33 #include "ProcessElfCore.h"
34 #include "RegisterContextLinuxCore_x86_64.h"
35 #include "RegisterContextPOSIXCore_arm.h"
36 #include "RegisterContextPOSIXCore_arm64.h"
37 #include "RegisterContextPOSIXCore_loongarch64.h"
38 #include "RegisterContextPOSIXCore_mips64.h"
39 #include "RegisterContextPOSIXCore_powerpc.h"
40 #include "RegisterContextPOSIXCore_ppc64le.h"
41 #include "RegisterContextPOSIXCore_riscv64.h"
42 #include "RegisterContextPOSIXCore_s390x.h"
43 #include "RegisterContextPOSIXCore_x86_64.h"
44 #include "ThreadElfCore.h"
45 
46 #include <memory>
47 
48 using namespace lldb;
49 using namespace lldb_private;
50 
51 // Construct a Thread object with given data
52 ThreadElfCore::ThreadElfCore(Process &process, const ThreadData &td)
53     : Thread(process, td.tid), m_thread_name(td.name), m_thread_reg_ctx_sp(),
54       m_gpregset_data(td.gpregset), m_notes(td.notes),
55       m_siginfo(std::move(td.siginfo)) {}
56 
57 ThreadElfCore::~ThreadElfCore() { DestroyThread(); }
58 
59 void ThreadElfCore::RefreshStateAfterStop() {
60   GetRegisterContext()->InvalidateIfNeeded(false);
61 }
62 
63 RegisterContextSP ThreadElfCore::GetRegisterContext() {
64   if (!m_reg_context_sp) {
65     m_reg_context_sp = CreateRegisterContextForFrame(nullptr);
66   }
67   return m_reg_context_sp;
68 }
69 
70 RegisterContextSP
71 ThreadElfCore::CreateRegisterContextForFrame(StackFrame *frame) {
72   RegisterContextSP reg_ctx_sp;
73   uint32_t concrete_frame_idx = 0;
74   Log *log = GetLog(LLDBLog::Thread);
75 
76   if (frame)
77     concrete_frame_idx = frame->GetConcreteFrameIndex();
78 
79   bool is_linux = false;
80   if (concrete_frame_idx == 0) {
81     if (m_thread_reg_ctx_sp)
82       return m_thread_reg_ctx_sp;
83 
84     ProcessElfCore *process = static_cast<ProcessElfCore *>(GetProcess().get());
85     ArchSpec arch = process->GetArchitecture();
86     RegisterInfoInterface *reg_interface = nullptr;
87 
88     switch (arch.GetTriple().getOS()) {
89     case llvm::Triple::FreeBSD: {
90       switch (arch.GetMachine()) {
91       case llvm::Triple::aarch64:
92       case llvm::Triple::arm:
93         break;
94       case llvm::Triple::ppc:
95         reg_interface = new RegisterContextFreeBSD_powerpc32(arch);
96         break;
97       case llvm::Triple::ppc64:
98         reg_interface = new RegisterContextFreeBSD_powerpc64(arch);
99         break;
100       case llvm::Triple::mips64:
101         reg_interface = new RegisterContextFreeBSD_mips64(arch);
102         break;
103       case llvm::Triple::x86:
104         reg_interface = new RegisterContextFreeBSD_i386(arch);
105         break;
106       case llvm::Triple::x86_64:
107         reg_interface = new RegisterContextFreeBSD_x86_64(arch);
108         break;
109       default:
110         break;
111       }
112       break;
113     }
114 
115     case llvm::Triple::NetBSD: {
116       switch (arch.GetMachine()) {
117       case llvm::Triple::aarch64:
118         break;
119       case llvm::Triple::x86:
120         reg_interface = new RegisterContextNetBSD_i386(arch);
121         break;
122       case llvm::Triple::x86_64:
123         reg_interface = new RegisterContextNetBSD_x86_64(arch);
124         break;
125       default:
126         break;
127       }
128       break;
129     }
130 
131     case llvm::Triple::Linux: {
132       is_linux = true;
133       switch (arch.GetMachine()) {
134       case llvm::Triple::aarch64:
135         break;
136       case llvm::Triple::ppc64le:
137         reg_interface = new RegisterInfoPOSIX_ppc64le(arch);
138         break;
139       case llvm::Triple::systemz:
140         reg_interface = new RegisterContextLinux_s390x(arch);
141         break;
142       case llvm::Triple::x86:
143         reg_interface = new RegisterContextLinux_i386(arch);
144         break;
145       case llvm::Triple::x86_64:
146         reg_interface = new RegisterContextLinux_x86_64(arch);
147         break;
148       default:
149         break;
150       }
151       break;
152     }
153 
154     case llvm::Triple::OpenBSD: {
155       switch (arch.GetMachine()) {
156       case llvm::Triple::aarch64:
157         break;
158       case llvm::Triple::x86:
159         reg_interface = new RegisterContextOpenBSD_i386(arch);
160         break;
161       case llvm::Triple::x86_64:
162         reg_interface = new RegisterContextOpenBSD_x86_64(arch);
163         break;
164       default:
165         break;
166       }
167       break;
168     }
169 
170     default:
171       break;
172     }
173 
174     if (!reg_interface && arch.GetMachine() != llvm::Triple::aarch64 &&
175         arch.GetMachine() != llvm::Triple::arm &&
176         arch.GetMachine() != llvm::Triple::loongarch64 &&
177         arch.GetMachine() != llvm::Triple::riscv64) {
178       LLDB_LOGF(log, "elf-core::%s:: Architecture(%d) or OS(%d) not supported",
179                 __FUNCTION__, arch.GetMachine(), arch.GetTriple().getOS());
180       assert(false && "Architecture or OS not supported");
181     }
182 
183     switch (arch.GetMachine()) {
184     case llvm::Triple::aarch64:
185       m_thread_reg_ctx_sp = RegisterContextCorePOSIX_arm64::Create(
186           *this, arch, m_gpregset_data, m_notes);
187       break;
188     case llvm::Triple::arm:
189       m_thread_reg_ctx_sp = std::make_shared<RegisterContextCorePOSIX_arm>(
190           *this, std::make_unique<RegisterInfoPOSIX_arm>(arch), m_gpregset_data,
191           m_notes);
192       break;
193     case llvm::Triple::loongarch64:
194       m_thread_reg_ctx_sp = RegisterContextCorePOSIX_loongarch64::Create(
195           *this, arch, m_gpregset_data, m_notes);
196       break;
197     case llvm::Triple::riscv64:
198       m_thread_reg_ctx_sp = RegisterContextCorePOSIX_riscv64::Create(
199           *this, arch, m_gpregset_data, m_notes);
200       break;
201     case llvm::Triple::mipsel:
202     case llvm::Triple::mips:
203       m_thread_reg_ctx_sp = std::make_shared<RegisterContextCorePOSIX_mips64>(
204           *this, reg_interface, m_gpregset_data, m_notes);
205       break;
206     case llvm::Triple::mips64:
207     case llvm::Triple::mips64el:
208       m_thread_reg_ctx_sp = std::make_shared<RegisterContextCorePOSIX_mips64>(
209           *this, reg_interface, m_gpregset_data, m_notes);
210       break;
211     case llvm::Triple::ppc:
212     case llvm::Triple::ppc64:
213       m_thread_reg_ctx_sp = std::make_shared<RegisterContextCorePOSIX_powerpc>(
214           *this, reg_interface, m_gpregset_data, m_notes);
215       break;
216     case llvm::Triple::ppc64le:
217       m_thread_reg_ctx_sp = std::make_shared<RegisterContextCorePOSIX_ppc64le>(
218           *this, reg_interface, m_gpregset_data, m_notes);
219       break;
220     case llvm::Triple::systemz:
221       m_thread_reg_ctx_sp = std::make_shared<RegisterContextCorePOSIX_s390x>(
222           *this, reg_interface, m_gpregset_data, m_notes);
223       break;
224     case llvm::Triple::x86:
225     case llvm::Triple::x86_64:
226       if (is_linux) {
227         m_thread_reg_ctx_sp = std::make_shared<RegisterContextLinuxCore_x86_64>(
228               *this, reg_interface, m_gpregset_data, m_notes);
229       } else {
230         m_thread_reg_ctx_sp = std::make_shared<RegisterContextCorePOSIX_x86_64>(
231               *this, reg_interface, m_gpregset_data, m_notes);
232       }
233       break;
234     default:
235       break;
236     }
237 
238     reg_ctx_sp = m_thread_reg_ctx_sp;
239   } else {
240     reg_ctx_sp = GetUnwinder().CreateRegisterContextForFrame(frame);
241   }
242   return reg_ctx_sp;
243 }
244 
245 bool ThreadElfCore::CalculateStopInfo() {
246   ProcessSP process_sp(GetProcess());
247   if (!process_sp)
248     return false;
249 
250   lldb::UnixSignalsSP unix_signals_sp(process_sp->GetUnixSignals());
251   if (!unix_signals_sp)
252     return false;
253 
254   const char *sig_description;
255   std::string description = m_siginfo.GetDescription(*unix_signals_sp);
256   if (description.empty())
257     sig_description = nullptr;
258   else
259     sig_description = description.c_str();
260 
261   SetStopInfo(StopInfo::CreateStopReasonWithSignal(
262       *this, m_siginfo.si_signo, sig_description, m_siginfo.si_code));
263 
264   SetStopInfo(m_stop_info_sp);
265   return true;
266 }
267 
268 // Parse PRSTATUS from NOTE entry
269 ELFLinuxPrStatus::ELFLinuxPrStatus() {
270   memset(this, 0, sizeof(ELFLinuxPrStatus));
271 }
272 
273 size_t ELFLinuxPrStatus::GetSize(const lldb_private::ArchSpec &arch) {
274   constexpr size_t mips_linux_pr_status_size_o32 = 96;
275   constexpr size_t mips_linux_pr_status_size_n32 = 72;
276   constexpr size_t num_ptr_size_members = 10;
277   if (arch.IsMIPS()) {
278     std::string abi = arch.GetTargetABI();
279     assert(!abi.empty() && "ABI is not set");
280     if (!abi.compare("n64"))
281       return sizeof(ELFLinuxPrStatus);
282     else if (!abi.compare("o32"))
283       return mips_linux_pr_status_size_o32;
284     // N32 ABI
285     return mips_linux_pr_status_size_n32;
286   }
287   switch (arch.GetCore()) {
288   case lldb_private::ArchSpec::eCore_x86_32_i386:
289   case lldb_private::ArchSpec::eCore_x86_32_i486:
290     return 72;
291   default:
292     if (arch.GetAddressByteSize() == 8)
293       return sizeof(ELFLinuxPrStatus);
294     else
295       return sizeof(ELFLinuxPrStatus) - num_ptr_size_members * 4;
296   }
297 }
298 
299 Status ELFLinuxPrStatus::Parse(const DataExtractor &data,
300                                const ArchSpec &arch) {
301   Status error;
302   if (GetSize(arch) > data.GetByteSize()) {
303     error = Status::FromErrorStringWithFormat(
304         "NT_PRSTATUS size should be %zu, but the remaining bytes are: %" PRIu64,
305         GetSize(arch), data.GetByteSize());
306     return error;
307   }
308 
309   // Read field by field to correctly account for endianess of both the core
310   // dump and the platform running lldb.
311   offset_t offset = 0;
312   si_signo = data.GetU32(&offset);
313   si_code = data.GetU32(&offset);
314   si_errno = data.GetU32(&offset);
315 
316   pr_cursig = data.GetU16(&offset);
317   offset += 2; // pad
318 
319   pr_sigpend = data.GetAddress(&offset);
320   pr_sighold = data.GetAddress(&offset);
321 
322   pr_pid = data.GetU32(&offset);
323   pr_ppid = data.GetU32(&offset);
324   pr_pgrp = data.GetU32(&offset);
325   pr_sid = data.GetU32(&offset);
326 
327   pr_utime.tv_sec = data.GetAddress(&offset);
328   pr_utime.tv_usec = data.GetAddress(&offset);
329 
330   pr_stime.tv_sec = data.GetAddress(&offset);
331   pr_stime.tv_usec = data.GetAddress(&offset);
332 
333   pr_cutime.tv_sec = data.GetAddress(&offset);
334   pr_cutime.tv_usec = data.GetAddress(&offset);
335 
336   pr_cstime.tv_sec = data.GetAddress(&offset);
337   pr_cstime.tv_usec = data.GetAddress(&offset);
338 
339   return error;
340 }
341 
342 static struct compat_timeval
343 copy_timespecs(const ProcessInstanceInfo::timespec &oth) {
344   using sec_t = decltype(compat_timeval::tv_sec);
345   using usec_t = decltype(compat_timeval::tv_usec);
346   return {static_cast<sec_t>(oth.tv_sec), static_cast<usec_t>(oth.tv_usec)};
347 }
348 
349 std::optional<ELFLinuxPrStatus>
350 ELFLinuxPrStatus::Populate(const lldb::ThreadSP &thread_sp) {
351   ELFLinuxPrStatus prstatus{};
352   prstatus.pr_pid = thread_sp->GetID();
353   lldb::ProcessSP process_sp = thread_sp->GetProcess();
354   ProcessInstanceInfo info;
355   if (!process_sp->GetProcessInfo(info))
356     return std::nullopt;
357 
358   prstatus.pr_ppid = info.GetParentProcessID();
359   prstatus.pr_pgrp = info.GetProcessGroupID();
360   prstatus.pr_sid = info.GetProcessSessionID();
361   prstatus.pr_utime = copy_timespecs(info.GetUserTime());
362   prstatus.pr_stime = copy_timespecs(info.GetSystemTime());
363   prstatus.pr_cutime = copy_timespecs(info.GetCumulativeUserTime());
364   prstatus.pr_cstime = copy_timespecs(info.GetCumulativeSystemTime());
365   return prstatus;
366 }
367 
368 // Parse PRPSINFO from NOTE entry
369 ELFLinuxPrPsInfo::ELFLinuxPrPsInfo() {
370   memset(this, 0, sizeof(ELFLinuxPrPsInfo));
371 }
372 
373 size_t ELFLinuxPrPsInfo::GetSize(const lldb_private::ArchSpec &arch) {
374   constexpr size_t mips_linux_pr_psinfo_size_o32_n32 = 128;
375   if (arch.IsMIPS()) {
376     uint8_t address_byte_size = arch.GetAddressByteSize();
377     if (address_byte_size == 8)
378       return sizeof(ELFLinuxPrPsInfo);
379     return mips_linux_pr_psinfo_size_o32_n32;
380   }
381 
382   switch (arch.GetCore()) {
383   case lldb_private::ArchSpec::eCore_s390x_generic:
384   case lldb_private::ArchSpec::eCore_x86_64_x86_64:
385     return sizeof(ELFLinuxPrPsInfo);
386   case lldb_private::ArchSpec::eCore_x86_32_i386:
387   case lldb_private::ArchSpec::eCore_x86_32_i486:
388     return 124;
389   default:
390     return 0;
391   }
392 }
393 
394 Status ELFLinuxPrPsInfo::Parse(const DataExtractor &data,
395                                const ArchSpec &arch) {
396   Status error;
397   ByteOrder byteorder = data.GetByteOrder();
398   if (GetSize(arch) > data.GetByteSize()) {
399     error = Status::FromErrorStringWithFormat(
400         "NT_PRPSINFO size should be %zu, but the remaining bytes are: %" PRIu64,
401         GetSize(arch), data.GetByteSize());
402     return error;
403   }
404   size_t size = 0;
405   offset_t offset = 0;
406 
407   pr_state = data.GetU8(&offset);
408   pr_sname = data.GetU8(&offset);
409   pr_zomb = data.GetU8(&offset);
410   pr_nice = data.GetU8(&offset);
411   if (data.GetAddressByteSize() == 8) {
412     // Word align the next field on 64 bit.
413     offset += 4;
414   }
415 
416   pr_flag = data.GetAddress(&offset);
417 
418   if (arch.IsMIPS()) {
419     // The pr_uid and pr_gid is always 32 bit irrespective of platforms
420     pr_uid = data.GetU32(&offset);
421     pr_gid = data.GetU32(&offset);
422   } else {
423     // 16 bit on 32 bit platforms, 32 bit on 64 bit platforms
424     pr_uid = data.GetMaxU64(&offset, data.GetAddressByteSize() >> 1);
425     pr_gid = data.GetMaxU64(&offset, data.GetAddressByteSize() >> 1);
426   }
427 
428   pr_pid = data.GetU32(&offset);
429   pr_ppid = data.GetU32(&offset);
430   pr_pgrp = data.GetU32(&offset);
431   pr_sid = data.GetU32(&offset);
432 
433   size = 16;
434   data.ExtractBytes(offset, size, byteorder, pr_fname);
435   offset += size;
436 
437   size = 80;
438   data.ExtractBytes(offset, size, byteorder, pr_psargs);
439   offset += size;
440 
441   return error;
442 }
443 
444 std::optional<ELFLinuxPrPsInfo>
445 ELFLinuxPrPsInfo::Populate(const lldb::ProcessSP &process_sp) {
446   ProcessInstanceInfo info;
447   if (!process_sp->GetProcessInfo(info))
448     return std::nullopt;
449 
450   return Populate(info, process_sp->GetState());
451 }
452 
453 std::optional<ELFLinuxPrPsInfo>
454 ELFLinuxPrPsInfo::Populate(const lldb_private::ProcessInstanceInfo &info,
455                            lldb::StateType process_state) {
456   ELFLinuxPrPsInfo prpsinfo{};
457   prpsinfo.pr_pid = info.GetProcessID();
458   prpsinfo.pr_nice = info.GetPriorityValue().value_or(0);
459   prpsinfo.pr_zomb = 0;
460   if (auto zombie_opt = info.IsZombie(); zombie_opt.value_or(false)) {
461     prpsinfo.pr_zomb = 1;
462   }
463   /**
464    * In the linux kernel this comes from:
465    * state = READ_ONCE(p->__state);
466    * i = state ? ffz(~state) + 1 : 0;
467    * psinfo->pr_sname = (i > 5) ? '.' : "RSDTZW"[i];
468    *
469    * So we replicate that here. From proc_pid_stats(5)
470    * R = Running
471    * S = Sleeping on uninterrutible wait
472    * D = Waiting on uninterruptable disk sleep
473    * T = Tracing stop
474    * Z = Zombie
475    * W = Paging
476    */
477   switch (process_state) {
478   case lldb::StateType::eStateSuspended:
479     prpsinfo.pr_sname = 'S';
480     prpsinfo.pr_state = 1;
481     break;
482   case lldb::StateType::eStateStopped:
483     [[fallthrough]];
484   case lldb::StateType::eStateStepping:
485     prpsinfo.pr_sname = 'T';
486     prpsinfo.pr_state = 3;
487     break;
488   case lldb::StateType::eStateUnloaded:
489     [[fallthrough]];
490   case lldb::StateType::eStateRunning:
491     prpsinfo.pr_sname = 'R';
492     prpsinfo.pr_state = 0;
493     break;
494   default:
495     break;
496   }
497 
498   /**
499    * pr_flags is left as 0. The values (in linux) are specific
500    * to the kernel. We recover them from the proc filesystem
501    * but don't put them in ProcessInfo because it would really
502    * become very linux specific and the utility here seems pretty
503    * dubious
504    */
505 
506   if (info.EffectiveUserIDIsValid())
507     prpsinfo.pr_uid = info.GetUserID();
508 
509   if (info.EffectiveGroupIDIsValid())
510     prpsinfo.pr_gid = info.GetGroupID();
511 
512   if (info.ParentProcessIDIsValid())
513     prpsinfo.pr_ppid = info.GetParentProcessID();
514 
515   if (info.ProcessGroupIDIsValid())
516     prpsinfo.pr_pgrp = info.GetProcessGroupID();
517 
518   if (info.ProcessSessionIDIsValid())
519     prpsinfo.pr_sid = info.GetProcessSessionID();
520 
521   constexpr size_t fname_len = std::extent_v<decltype(prpsinfo.pr_fname)>;
522   static_assert(fname_len > 0, "This should always be non zero");
523   const llvm::StringRef fname = info.GetNameAsStringRef();
524   auto fname_begin = fname.begin();
525   std::copy_n(fname_begin, std::min(fname_len, fname.size()),
526               prpsinfo.pr_fname);
527   prpsinfo.pr_fname[fname_len - 1] = '\0';
528   auto args = info.GetArguments();
529   auto argentry_iterator = std::begin(args);
530   char *psargs = prpsinfo.pr_psargs;
531   char *psargs_end = std::end(prpsinfo.pr_psargs);
532   while (psargs < psargs_end && argentry_iterator != args.end()) {
533     llvm::StringRef argentry = argentry_iterator->ref();
534     size_t len =
535         std::min<size_t>(std::distance(psargs, psargs_end), argentry.size());
536     auto arg_iterator = std::begin(argentry);
537     psargs = std::copy_n(arg_iterator, len, psargs);
538     if (psargs != psargs_end)
539       *(psargs++) = ' ';
540     ++argentry_iterator;
541   }
542   *(psargs - 1) = '\0';
543   return prpsinfo;
544 }
545 
546 // Parse SIGINFO from NOTE entry
547 ELFLinuxSigInfo::ELFLinuxSigInfo() { memset(this, 0, sizeof(ELFLinuxSigInfo)); }
548 
549 size_t ELFLinuxSigInfo::GetSize(const lldb_private::ArchSpec &arch) {
550   if (arch.IsMIPS())
551     return sizeof(ELFLinuxSigInfo);
552   switch (arch.GetCore()) {
553   case lldb_private::ArchSpec::eCore_x86_64_x86_64:
554     return sizeof(ELFLinuxSigInfo);
555   case lldb_private::ArchSpec::eCore_s390x_generic:
556   case lldb_private::ArchSpec::eCore_x86_32_i386:
557   case lldb_private::ArchSpec::eCore_x86_32_i486:
558     return 12;
559   default:
560     return 0;
561   }
562 }
563 
564 Status ELFLinuxSigInfo::Parse(const DataExtractor &data, const ArchSpec &arch,
565                               const lldb_private::UnixSignals &unix_signals) {
566   Status error;
567   uint64_t size = GetSize(arch);
568   if (size > data.GetByteSize()) {
569     error = Status::FromErrorStringWithFormat(
570         "NT_SIGINFO size should be %zu, but the remaining bytes are: %" PRIu64,
571         GetSize(arch), data.GetByteSize());
572     return error;
573   }
574 
575   // Set that we've parsed the siginfo from a SIGINFO note.
576   note_type = eNT_SIGINFO;
577   // Parsing from a 32 bit ELF core file, and populating/reusing the structure
578   // properly, because the struct is for the 64 bit version
579   offset_t offset = 0;
580   si_signo = data.GetU32(&offset);
581   si_errno = data.GetU32(&offset);
582   si_code = data.GetU32(&offset);
583   // 64b ELF have a 4 byte pad.
584   if (data.GetAddressByteSize() == 8)
585     offset += 4;
586   // Not every stop signal has a valid address, but that will get resolved in
587   // the unix_signals.GetSignalDescription() call below.
588   if (unix_signals.GetShouldStop(si_signo)) {
589     // Instead of memcpy we call all these individually as the extractor will
590     // handle endianness for us.
591     sigfault.si_addr = data.GetAddress(&offset);
592     sigfault.si_addr_lsb = data.GetU16(&offset);
593     if (data.GetByteSize() - offset >= sizeof(sigfault.bounds)) {
594       sigfault.bounds._addr_bnd._lower = data.GetAddress(&offset);
595       sigfault.bounds._addr_bnd._upper = data.GetAddress(&offset);
596       sigfault.bounds._pkey = data.GetU32(&offset);
597     } else {
598       // Set these to 0 so we don't use bogus data for the description.
599       sigfault.bounds._addr_bnd._lower = 0;
600       sigfault.bounds._addr_bnd._upper = 0;
601       sigfault.bounds._pkey = 0;
602     }
603   }
604 
605   return error;
606 }
607 
608 std::string ELFLinuxSigInfo::GetDescription(
609     const lldb_private::UnixSignals &unix_signals) const {
610   if (unix_signals.GetShouldStop(si_signo) && note_type == eNT_SIGINFO) {
611     if (sigfault.bounds._addr_bnd._upper != 0)
612       return unix_signals.GetSignalDescription(
613           si_signo, si_code, sigfault.si_addr, sigfault.bounds._addr_bnd._lower,
614           sigfault.bounds._addr_bnd._upper);
615     else
616       return unix_signals.GetSignalDescription(si_signo, si_code,
617                                                sigfault.si_addr);
618   }
619 
620   // This looks weird, but there is an existing pattern where we don't pass a
621   // description to keep up with that, we return empty here, and then the above
622   // function will set the description whether or not this is empty.
623   return std::string();
624 }
625