1 //===-- IRMemoryMap.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/Expression/IRMemoryMap.h"
10 #include "lldb/Target/MemoryRegionInfo.h"
11 #include "lldb/Target/Process.h"
12 #include "lldb/Target/Target.h"
13 #include "lldb/Utility/DataBufferHeap.h"
14 #include "lldb/Utility/DataExtractor.h"
15 #include "lldb/Utility/LLDBAssert.h"
16 #include "lldb/Utility/LLDBLog.h"
17 #include "lldb/Utility/Log.h"
18 #include "lldb/Utility/Scalar.h"
19 #include "lldb/Utility/Status.h"
20 
21 using namespace lldb_private;
22 
23 IRMemoryMap::IRMemoryMap(lldb::TargetSP target_sp) : m_target_wp(target_sp) {
24   if (target_sp)
25     m_process_wp = target_sp->GetProcessSP();
26 }
27 
28 IRMemoryMap::~IRMemoryMap() {
29   lldb::ProcessSP process_sp = m_process_wp.lock();
30 
31   if (process_sp) {
32     AllocationMap::iterator iter;
33 
34     Status err;
35 
36     while ((iter = m_allocations.begin()) != m_allocations.end()) {
37       err.Clear();
38       if (iter->second.m_leak)
39         m_allocations.erase(iter);
40       else
41         Free(iter->first, err);
42     }
43   }
44 }
45 
46 lldb::addr_t IRMemoryMap::FindSpace(size_t size) {
47   // The FindSpace algorithm's job is to find a region of memory that the
48   // underlying process is unlikely to be using.
49   //
50   // The memory returned by this function will never be written to.  The only
51   // point is that it should not shadow process memory if possible, so that
52   // expressions processing real values from the process do not use the wrong
53   // data.
54   //
55   // If the process can in fact allocate memory (CanJIT() lets us know this)
56   // then this can be accomplished just be allocating memory in the inferior.
57   // Then no guessing is required.
58 
59   lldb::TargetSP target_sp = m_target_wp.lock();
60   lldb::ProcessSP process_sp = m_process_wp.lock();
61 
62   const bool process_is_alive = process_sp && process_sp->IsAlive();
63 
64   lldb::addr_t ret = LLDB_INVALID_ADDRESS;
65   if (size == 0)
66     return ret;
67 
68   if (process_is_alive && process_sp->CanJIT()) {
69     Status alloc_error;
70 
71     ret = process_sp->AllocateMemory(size, lldb::ePermissionsReadable |
72                                                lldb::ePermissionsWritable,
73                                      alloc_error);
74 
75     if (!alloc_error.Success())
76       return LLDB_INVALID_ADDRESS;
77     else
78       return ret;
79   }
80 
81   // At this point we know that we need to hunt.
82   //
83   // First, go to the end of the existing allocations we've made if there are
84   // any allocations.  Otherwise start at the beginning of memory.
85 
86   if (m_allocations.empty()) {
87     ret = 0x0;
88   } else {
89     auto back = m_allocations.rbegin();
90     lldb::addr_t addr = back->first;
91     size_t alloc_size = back->second.m_size;
92     ret = llvm::alignTo(addr + alloc_size, 4096);
93   }
94 
95   uint64_t end_of_memory;
96   switch (GetAddressByteSize()) {
97   case 2:
98     end_of_memory = 0xffffull;
99     break;
100   case 4:
101     end_of_memory = 0xffffffffull;
102     break;
103   case 8:
104     end_of_memory = 0xffffffffffffffffull;
105     break;
106   default:
107     lldbassert(false && "Invalid address size.");
108     return LLDB_INVALID_ADDRESS;
109   }
110 
111   // Now, if it's possible to use the GetMemoryRegionInfo API to detect mapped
112   // regions, walk forward through memory until a region is found that has
113   // adequate space for our allocation.
114   if (process_is_alive) {
115     MemoryRegionInfo region_info;
116     Status err = process_sp->GetMemoryRegionInfo(ret, region_info);
117     if (err.Success()) {
118       while (true) {
119         if (region_info.GetReadable() != MemoryRegionInfo::OptionalBool::eNo ||
120             region_info.GetWritable() != MemoryRegionInfo::OptionalBool::eNo ||
121             region_info.GetExecutable() !=
122                 MemoryRegionInfo::OptionalBool::eNo) {
123           if (region_info.GetRange().GetRangeEnd() - 1 >= end_of_memory) {
124             ret = LLDB_INVALID_ADDRESS;
125             break;
126           } else {
127             ret = region_info.GetRange().GetRangeEnd();
128           }
129         } else if (ret + size < region_info.GetRange().GetRangeEnd()) {
130           return ret;
131         } else {
132           // ret stays the same.  We just need to walk a bit further.
133         }
134 
135         err = process_sp->GetMemoryRegionInfo(
136             region_info.GetRange().GetRangeEnd(), region_info);
137         if (err.Fail()) {
138           lldbassert(0 && "GetMemoryRegionInfo() succeeded, then failed");
139           ret = LLDB_INVALID_ADDRESS;
140           break;
141         }
142       }
143     }
144   }
145 
146   // We've tried our algorithm, and it didn't work.  Now we have to reset back
147   // to the end of the allocations we've already reported, or use a 'sensible'
148   // default if this is our first allocation.
149   if (m_allocations.empty()) {
150     uint64_t alloc_address = target_sp->GetExprAllocAddress();
151     if (alloc_address > 0) {
152       if (alloc_address >= end_of_memory) {
153         lldbassert(0 && "The allocation address for expression evaluation must "
154                         "be within process address space");
155         return LLDB_INVALID_ADDRESS;
156       }
157       ret = alloc_address;
158     } else {
159       uint32_t address_byte_size = GetAddressByteSize();
160       if (address_byte_size != UINT32_MAX) {
161         switch (address_byte_size) {
162         case 2:
163           ret = 0x8000ull;
164           break;
165         case 4:
166           ret = 0xee000000ull;
167           break;
168         case 8:
169           ret = 0xdead0fff00000000ull;
170           break;
171         default:
172           lldbassert(false && "Invalid address size.");
173           return LLDB_INVALID_ADDRESS;
174         }
175       }
176     }
177   } else {
178     auto back = m_allocations.rbegin();
179     lldb::addr_t addr = back->first;
180     size_t alloc_size = back->second.m_size;
181     uint64_t align = target_sp->GetExprAllocAlign();
182     if (align == 0)
183       align = 4096;
184     ret = llvm::alignTo(addr + alloc_size, align);
185   }
186 
187   return ret;
188 }
189 
190 IRMemoryMap::AllocationMap::iterator
191 IRMemoryMap::FindAllocation(lldb::addr_t addr, size_t size) {
192   if (addr == LLDB_INVALID_ADDRESS)
193     return m_allocations.end();
194 
195   AllocationMap::iterator iter = m_allocations.lower_bound(addr);
196 
197   if (iter == m_allocations.end() || iter->first > addr) {
198     if (iter == m_allocations.begin())
199       return m_allocations.end();
200     iter--;
201   }
202 
203   if (iter->first <= addr && iter->first + iter->second.m_size >= addr + size)
204     return iter;
205 
206   return m_allocations.end();
207 }
208 
209 bool IRMemoryMap::IntersectsAllocation(lldb::addr_t addr, size_t size) const {
210   if (addr == LLDB_INVALID_ADDRESS)
211     return false;
212 
213   AllocationMap::const_iterator iter = m_allocations.lower_bound(addr);
214 
215   // Since we only know that the returned interval begins at a location greater
216   // than or equal to where the given interval begins, it's possible that the
217   // given interval intersects either the returned interval or the previous
218   // interval.  Thus, we need to check both. Note that we only need to check
219   // these two intervals.  Since all intervals are disjoint it is not possible
220   // that an adjacent interval does not intersect, but a non-adjacent interval
221   // does intersect.
222   if (iter != m_allocations.end()) {
223     if (AllocationsIntersect(addr, size, iter->second.m_process_start,
224                              iter->second.m_size))
225       return true;
226   }
227 
228   if (iter != m_allocations.begin()) {
229     --iter;
230     if (AllocationsIntersect(addr, size, iter->second.m_process_start,
231                              iter->second.m_size))
232       return true;
233   }
234 
235   return false;
236 }
237 
238 bool IRMemoryMap::AllocationsIntersect(lldb::addr_t addr1, size_t size1,
239                                        lldb::addr_t addr2, size_t size2) {
240   // Given two half open intervals [A, B) and [X, Y), the only 6 permutations
241   // that satisfy A<B and X<Y are the following:
242   // A B X Y
243   // A X B Y  (intersects)
244   // A X Y B  (intersects)
245   // X A B Y  (intersects)
246   // X A Y B  (intersects)
247   // X Y A B
248   // The first is B <= X, and the last is Y <= A. So the condition is !(B <= X
249   // || Y <= A)), or (X < B && A < Y)
250   return (addr2 < (addr1 + size1)) && (addr1 < (addr2 + size2));
251 }
252 
253 lldb::ByteOrder IRMemoryMap::GetByteOrder() {
254   lldb::ProcessSP process_sp = m_process_wp.lock();
255 
256   if (process_sp)
257     return process_sp->GetByteOrder();
258 
259   lldb::TargetSP target_sp = m_target_wp.lock();
260 
261   if (target_sp)
262     return target_sp->GetArchitecture().GetByteOrder();
263 
264   return lldb::eByteOrderInvalid;
265 }
266 
267 uint32_t IRMemoryMap::GetAddressByteSize() {
268   lldb::ProcessSP process_sp = m_process_wp.lock();
269 
270   if (process_sp)
271     return process_sp->GetAddressByteSize();
272 
273   lldb::TargetSP target_sp = m_target_wp.lock();
274 
275   if (target_sp)
276     return target_sp->GetArchitecture().GetAddressByteSize();
277 
278   return UINT32_MAX;
279 }
280 
281 ExecutionContextScope *IRMemoryMap::GetBestExecutionContextScope() const {
282   lldb::ProcessSP process_sp = m_process_wp.lock();
283 
284   if (process_sp)
285     return process_sp.get();
286 
287   lldb::TargetSP target_sp = m_target_wp.lock();
288 
289   if (target_sp)
290     return target_sp.get();
291 
292   return nullptr;
293 }
294 
295 IRMemoryMap::Allocation::Allocation(lldb::addr_t process_alloc,
296                                     lldb::addr_t process_start, size_t size,
297                                     uint32_t permissions, uint8_t alignment,
298                                     AllocationPolicy policy)
299     : m_process_alloc(process_alloc), m_process_start(process_start),
300       m_size(size), m_policy(policy), m_leak(false), m_permissions(permissions),
301       m_alignment(alignment) {
302   switch (policy) {
303   default:
304     llvm_unreachable("Invalid AllocationPolicy");
305   case eAllocationPolicyHostOnly:
306   case eAllocationPolicyMirror:
307     m_data.SetByteSize(size);
308     break;
309   case eAllocationPolicyProcessOnly:
310     break;
311   }
312 }
313 
314 lldb::addr_t IRMemoryMap::Malloc(size_t size, uint8_t alignment,
315                                  uint32_t permissions, AllocationPolicy policy,
316                                  bool zero_memory, Status &error) {
317   lldb_private::Log *log(GetLog(LLDBLog::Expressions));
318   error.Clear();
319 
320   lldb::ProcessSP process_sp;
321   lldb::addr_t allocation_address = LLDB_INVALID_ADDRESS;
322   lldb::addr_t aligned_address = LLDB_INVALID_ADDRESS;
323 
324   size_t allocation_size;
325 
326   if (size == 0) {
327     // FIXME: Malloc(0) should either return an invalid address or assert, in
328     // order to cut down on unnecessary allocations.
329     allocation_size = alignment;
330   } else {
331     // Round up the requested size to an aligned value.
332     allocation_size = llvm::alignTo(size, alignment);
333 
334     // The process page cache does not see the requested alignment. We can't
335     // assume its result will be any more than 1-byte aligned. To work around
336     // this, request `alignment - 1` additional bytes.
337     allocation_size += alignment - 1;
338   }
339 
340   switch (policy) {
341   default:
342     error.SetErrorToGenericError();
343     error.SetErrorString("Couldn't malloc: invalid allocation policy");
344     return LLDB_INVALID_ADDRESS;
345   case eAllocationPolicyHostOnly:
346     allocation_address = FindSpace(allocation_size);
347     if (allocation_address == LLDB_INVALID_ADDRESS) {
348       error.SetErrorToGenericError();
349       error.SetErrorString("Couldn't malloc: address space is full");
350       return LLDB_INVALID_ADDRESS;
351     }
352     break;
353   case eAllocationPolicyMirror:
354     process_sp = m_process_wp.lock();
355     LLDB_LOGF(log,
356               "IRMemoryMap::%s process_sp=0x%" PRIxPTR
357               ", process_sp->CanJIT()=%s, process_sp->IsAlive()=%s",
358               __FUNCTION__, reinterpret_cast<uintptr_t>(process_sp.get()),
359               process_sp && process_sp->CanJIT() ? "true" : "false",
360               process_sp && process_sp->IsAlive() ? "true" : "false");
361     if (process_sp && process_sp->CanJIT() && process_sp->IsAlive()) {
362       if (!zero_memory)
363         allocation_address =
364             process_sp->AllocateMemory(allocation_size, permissions, error);
365       else
366         allocation_address =
367             process_sp->CallocateMemory(allocation_size, permissions, error);
368 
369       if (!error.Success())
370         return LLDB_INVALID_ADDRESS;
371     } else {
372       LLDB_LOGF(log,
373                 "IRMemoryMap::%s switching to eAllocationPolicyHostOnly "
374                 "due to failed condition (see previous expr log message)",
375                 __FUNCTION__);
376       policy = eAllocationPolicyHostOnly;
377       allocation_address = FindSpace(allocation_size);
378       if (allocation_address == LLDB_INVALID_ADDRESS) {
379         error.SetErrorToGenericError();
380         error.SetErrorString("Couldn't malloc: address space is full");
381         return LLDB_INVALID_ADDRESS;
382       }
383     }
384     break;
385   case eAllocationPolicyProcessOnly:
386     process_sp = m_process_wp.lock();
387     if (process_sp) {
388       if (process_sp->CanJIT() && process_sp->IsAlive()) {
389         if (!zero_memory)
390           allocation_address =
391               process_sp->AllocateMemory(allocation_size, permissions, error);
392         else
393           allocation_address =
394               process_sp->CallocateMemory(allocation_size, permissions, error);
395 
396         if (!error.Success())
397           return LLDB_INVALID_ADDRESS;
398       } else {
399         error.SetErrorToGenericError();
400         error.SetErrorString(
401             "Couldn't malloc: process doesn't support allocating memory");
402         return LLDB_INVALID_ADDRESS;
403       }
404     } else {
405       error.SetErrorToGenericError();
406       error.SetErrorString("Couldn't malloc: process doesn't exist, and this "
407                            "memory must be in the process");
408       return LLDB_INVALID_ADDRESS;
409     }
410     break;
411   }
412 
413   lldb::addr_t mask = alignment - 1;
414   aligned_address = (allocation_address + mask) & (~mask);
415 
416   m_allocations.emplace(
417       std::piecewise_construct, std::forward_as_tuple(aligned_address),
418       std::forward_as_tuple(allocation_address, aligned_address,
419                             allocation_size, permissions, alignment, policy));
420 
421   if (zero_memory) {
422     Status write_error;
423     std::vector<uint8_t> zero_buf(size, 0);
424     WriteMemory(aligned_address, zero_buf.data(), size, write_error);
425   }
426 
427   if (log) {
428     const char *policy_string;
429 
430     switch (policy) {
431     default:
432       policy_string = "<invalid policy>";
433       break;
434     case eAllocationPolicyHostOnly:
435       policy_string = "eAllocationPolicyHostOnly";
436       break;
437     case eAllocationPolicyProcessOnly:
438       policy_string = "eAllocationPolicyProcessOnly";
439       break;
440     case eAllocationPolicyMirror:
441       policy_string = "eAllocationPolicyMirror";
442       break;
443     }
444 
445     LLDB_LOGF(log,
446               "IRMemoryMap::Malloc (%" PRIu64 ", 0x%" PRIx64 ", 0x%" PRIx64
447               ", %s) -> 0x%" PRIx64,
448               (uint64_t)allocation_size, (uint64_t)alignment,
449               (uint64_t)permissions, policy_string, aligned_address);
450   }
451 
452   return aligned_address;
453 }
454 
455 void IRMemoryMap::Leak(lldb::addr_t process_address, Status &error) {
456   error.Clear();
457 
458   AllocationMap::iterator iter = m_allocations.find(process_address);
459 
460   if (iter == m_allocations.end()) {
461     error.SetErrorToGenericError();
462     error.SetErrorString("Couldn't leak: allocation doesn't exist");
463     return;
464   }
465 
466   Allocation &allocation = iter->second;
467 
468   allocation.m_leak = true;
469 }
470 
471 void IRMemoryMap::Free(lldb::addr_t process_address, Status &error) {
472   error.Clear();
473 
474   AllocationMap::iterator iter = m_allocations.find(process_address);
475 
476   if (iter == m_allocations.end()) {
477     error.SetErrorToGenericError();
478     error.SetErrorString("Couldn't free: allocation doesn't exist");
479     return;
480   }
481 
482   Allocation &allocation = iter->second;
483 
484   switch (allocation.m_policy) {
485   default:
486   case eAllocationPolicyHostOnly: {
487     lldb::ProcessSP process_sp = m_process_wp.lock();
488     if (process_sp) {
489       if (process_sp->CanJIT() && process_sp->IsAlive())
490         process_sp->DeallocateMemory(
491             allocation.m_process_alloc); // FindSpace allocated this for real
492     }
493 
494     break;
495   }
496   case eAllocationPolicyMirror:
497   case eAllocationPolicyProcessOnly: {
498     lldb::ProcessSP process_sp = m_process_wp.lock();
499     if (process_sp)
500       process_sp->DeallocateMemory(allocation.m_process_alloc);
501   }
502   }
503 
504   if (lldb_private::Log *log = GetLog(LLDBLog::Expressions)) {
505     LLDB_LOGF(log,
506               "IRMemoryMap::Free (0x%" PRIx64 ") freed [0x%" PRIx64
507               "..0x%" PRIx64 ")",
508               (uint64_t)process_address, iter->second.m_process_start,
509               iter->second.m_process_start + iter->second.m_size);
510   }
511 
512   m_allocations.erase(iter);
513 }
514 
515 bool IRMemoryMap::GetAllocSize(lldb::addr_t address, size_t &size) {
516   AllocationMap::iterator iter = FindAllocation(address, size);
517   if (iter == m_allocations.end())
518     return false;
519 
520   Allocation &al = iter->second;
521 
522   if (address > (al.m_process_start + al.m_size)) {
523     size = 0;
524     return false;
525   }
526 
527   if (address > al.m_process_start) {
528     int dif = address - al.m_process_start;
529     size = al.m_size - dif;
530     return true;
531   }
532 
533   size = al.m_size;
534   return true;
535 }
536 
537 void IRMemoryMap::WriteMemory(lldb::addr_t process_address,
538                               const uint8_t *bytes, size_t size,
539                               Status &error) {
540   error.Clear();
541 
542   AllocationMap::iterator iter = FindAllocation(process_address, size);
543 
544   if (iter == m_allocations.end()) {
545     lldb::ProcessSP process_sp = m_process_wp.lock();
546 
547     if (process_sp) {
548       process_sp->WriteMemory(process_address, bytes, size, error);
549       return;
550     }
551 
552     error.SetErrorToGenericError();
553     error.SetErrorString("Couldn't write: no allocation contains the target "
554                          "range and the process doesn't exist");
555     return;
556   }
557 
558   Allocation &allocation = iter->second;
559 
560   uint64_t offset = process_address - allocation.m_process_start;
561 
562   lldb::ProcessSP process_sp;
563 
564   switch (allocation.m_policy) {
565   default:
566     error.SetErrorToGenericError();
567     error.SetErrorString("Couldn't write: invalid allocation policy");
568     return;
569   case eAllocationPolicyHostOnly:
570     if (!allocation.m_data.GetByteSize()) {
571       error.SetErrorToGenericError();
572       error.SetErrorString("Couldn't write: data buffer is empty");
573       return;
574     }
575     ::memcpy(allocation.m_data.GetBytes() + offset, bytes, size);
576     break;
577   case eAllocationPolicyMirror:
578     if (!allocation.m_data.GetByteSize()) {
579       error.SetErrorToGenericError();
580       error.SetErrorString("Couldn't write: data buffer is empty");
581       return;
582     }
583     ::memcpy(allocation.m_data.GetBytes() + offset, bytes, size);
584     process_sp = m_process_wp.lock();
585     if (process_sp) {
586       process_sp->WriteMemory(process_address, bytes, size, error);
587       if (!error.Success())
588         return;
589     }
590     break;
591   case eAllocationPolicyProcessOnly:
592     process_sp = m_process_wp.lock();
593     if (process_sp) {
594       process_sp->WriteMemory(process_address, bytes, size, error);
595       if (!error.Success())
596         return;
597     }
598     break;
599   }
600 
601   if (lldb_private::Log *log = GetLog(LLDBLog::Expressions)) {
602     LLDB_LOGF(log,
603               "IRMemoryMap::WriteMemory (0x%" PRIx64 ", 0x%" PRIxPTR
604               ", 0x%" PRId64 ") went to [0x%" PRIx64 "..0x%" PRIx64 ")",
605               (uint64_t)process_address, reinterpret_cast<uintptr_t>(bytes), (uint64_t)size,
606               (uint64_t)allocation.m_process_start,
607               (uint64_t)allocation.m_process_start +
608                   (uint64_t)allocation.m_size);
609   }
610 }
611 
612 void IRMemoryMap::WriteScalarToMemory(lldb::addr_t process_address,
613                                       Scalar &scalar, size_t size,
614                                       Status &error) {
615   error.Clear();
616 
617   if (size == UINT32_MAX)
618     size = scalar.GetByteSize();
619 
620   if (size > 0) {
621     uint8_t buf[32];
622     const size_t mem_size =
623         scalar.GetAsMemoryData(buf, size, GetByteOrder(), error);
624     if (mem_size > 0) {
625       return WriteMemory(process_address, buf, mem_size, error);
626     } else {
627       error.SetErrorToGenericError();
628       error.SetErrorString(
629           "Couldn't write scalar: failed to get scalar as memory data");
630     }
631   } else {
632     error.SetErrorToGenericError();
633     error.SetErrorString("Couldn't write scalar: its size was zero");
634   }
635 }
636 
637 void IRMemoryMap::WritePointerToMemory(lldb::addr_t process_address,
638                                        lldb::addr_t address, Status &error) {
639   error.Clear();
640 
641   Scalar scalar(address);
642 
643   WriteScalarToMemory(process_address, scalar, GetAddressByteSize(), error);
644 }
645 
646 void IRMemoryMap::ReadMemory(uint8_t *bytes, lldb::addr_t process_address,
647                              size_t size, Status &error) {
648   error.Clear();
649 
650   AllocationMap::iterator iter = FindAllocation(process_address, size);
651 
652   if (iter == m_allocations.end()) {
653     lldb::ProcessSP process_sp = m_process_wp.lock();
654 
655     if (process_sp) {
656       process_sp->ReadMemory(process_address, bytes, size, error);
657       return;
658     }
659 
660     lldb::TargetSP target_sp = m_target_wp.lock();
661 
662     if (target_sp) {
663       Address absolute_address(process_address);
664       target_sp->ReadMemory(absolute_address, bytes, size, error, true);
665       return;
666     }
667 
668     error.SetErrorToGenericError();
669     error.SetErrorString("Couldn't read: no allocation contains the target "
670                          "range, and neither the process nor the target exist");
671     return;
672   }
673 
674   Allocation &allocation = iter->second;
675 
676   uint64_t offset = process_address - allocation.m_process_start;
677 
678   if (offset > allocation.m_size) {
679     error.SetErrorToGenericError();
680     error.SetErrorString("Couldn't read: data is not in the allocation");
681     return;
682   }
683 
684   lldb::ProcessSP process_sp;
685 
686   switch (allocation.m_policy) {
687   default:
688     error.SetErrorToGenericError();
689     error.SetErrorString("Couldn't read: invalid allocation policy");
690     return;
691   case eAllocationPolicyHostOnly:
692     if (!allocation.m_data.GetByteSize()) {
693       error.SetErrorToGenericError();
694       error.SetErrorString("Couldn't read: data buffer is empty");
695       return;
696     }
697     if (allocation.m_data.GetByteSize() < offset + size) {
698       error.SetErrorToGenericError();
699       error.SetErrorString("Couldn't read: not enough underlying data");
700       return;
701     }
702 
703     ::memcpy(bytes, allocation.m_data.GetBytes() + offset, size);
704     break;
705   case eAllocationPolicyMirror:
706     process_sp = m_process_wp.lock();
707     if (process_sp) {
708       process_sp->ReadMemory(process_address, bytes, size, error);
709       if (!error.Success())
710         return;
711     } else {
712       if (!allocation.m_data.GetByteSize()) {
713         error.SetErrorToGenericError();
714         error.SetErrorString("Couldn't read: data buffer is empty");
715         return;
716       }
717       ::memcpy(bytes, allocation.m_data.GetBytes() + offset, size);
718     }
719     break;
720   case eAllocationPolicyProcessOnly:
721     process_sp = m_process_wp.lock();
722     if (process_sp) {
723       process_sp->ReadMemory(process_address, bytes, size, error);
724       if (!error.Success())
725         return;
726     }
727     break;
728   }
729 
730   if (lldb_private::Log *log = GetLog(LLDBLog::Expressions)) {
731     LLDB_LOGF(log,
732               "IRMemoryMap::ReadMemory (0x%" PRIx64 ", 0x%" PRIxPTR
733               ", 0x%" PRId64 ") came from [0x%" PRIx64 "..0x%" PRIx64 ")",
734               (uint64_t)process_address, reinterpret_cast<uintptr_t>(bytes), (uint64_t)size,
735               (uint64_t)allocation.m_process_start,
736               (uint64_t)allocation.m_process_start +
737                   (uint64_t)allocation.m_size);
738   }
739 }
740 
741 void IRMemoryMap::ReadScalarFromMemory(Scalar &scalar,
742                                        lldb::addr_t process_address,
743                                        size_t size, Status &error) {
744   error.Clear();
745 
746   if (size > 0) {
747     DataBufferHeap buf(size, 0);
748     ReadMemory(buf.GetBytes(), process_address, size, error);
749 
750     if (!error.Success())
751       return;
752 
753     DataExtractor extractor(buf.GetBytes(), buf.GetByteSize(), GetByteOrder(),
754                             GetAddressByteSize());
755 
756     lldb::offset_t offset = 0;
757 
758     switch (size) {
759     default:
760       error.SetErrorToGenericError();
761       error.SetErrorStringWithFormat(
762           "Couldn't read scalar: unsupported size %" PRIu64, (uint64_t)size);
763       return;
764     case 1:
765       scalar = extractor.GetU8(&offset);
766       break;
767     case 2:
768       scalar = extractor.GetU16(&offset);
769       break;
770     case 4:
771       scalar = extractor.GetU32(&offset);
772       break;
773     case 8:
774       scalar = extractor.GetU64(&offset);
775       break;
776     }
777   } else {
778     error.SetErrorToGenericError();
779     error.SetErrorString("Couldn't read scalar: its size was zero");
780   }
781 }
782 
783 void IRMemoryMap::ReadPointerFromMemory(lldb::addr_t *address,
784                                         lldb::addr_t process_address,
785                                         Status &error) {
786   error.Clear();
787 
788   Scalar pointer_scalar;
789   ReadScalarFromMemory(pointer_scalar, process_address, GetAddressByteSize(),
790                        error);
791 
792   if (!error.Success())
793     return;
794 
795   *address = pointer_scalar.ULongLong();
796 }
797 
798 void IRMemoryMap::GetMemoryData(DataExtractor &extractor,
799                                 lldb::addr_t process_address, size_t size,
800                                 Status &error) {
801   error.Clear();
802 
803   if (size > 0) {
804     AllocationMap::iterator iter = FindAllocation(process_address, size);
805 
806     if (iter == m_allocations.end()) {
807       error.SetErrorToGenericError();
808       error.SetErrorStringWithFormat(
809           "Couldn't find an allocation containing [0x%" PRIx64 "..0x%" PRIx64
810           ")",
811           process_address, process_address + size);
812       return;
813     }
814 
815     Allocation &allocation = iter->second;
816 
817     switch (allocation.m_policy) {
818     default:
819       error.SetErrorToGenericError();
820       error.SetErrorString(
821           "Couldn't get memory data: invalid allocation policy");
822       return;
823     case eAllocationPolicyProcessOnly:
824       error.SetErrorToGenericError();
825       error.SetErrorString(
826           "Couldn't get memory data: memory is only in the target");
827       return;
828     case eAllocationPolicyMirror: {
829       lldb::ProcessSP process_sp = m_process_wp.lock();
830 
831       if (!allocation.m_data.GetByteSize()) {
832         error.SetErrorToGenericError();
833         error.SetErrorString("Couldn't get memory data: data buffer is empty");
834         return;
835       }
836       if (process_sp) {
837         process_sp->ReadMemory(allocation.m_process_start,
838                                allocation.m_data.GetBytes(),
839                                allocation.m_data.GetByteSize(), error);
840         if (!error.Success())
841           return;
842         uint64_t offset = process_address - allocation.m_process_start;
843         extractor = DataExtractor(allocation.m_data.GetBytes() + offset, size,
844                                   GetByteOrder(), GetAddressByteSize());
845         return;
846       }
847     } break;
848     case eAllocationPolicyHostOnly:
849       if (!allocation.m_data.GetByteSize()) {
850         error.SetErrorToGenericError();
851         error.SetErrorString("Couldn't get memory data: data buffer is empty");
852         return;
853       }
854       uint64_t offset = process_address - allocation.m_process_start;
855       extractor = DataExtractor(allocation.m_data.GetBytes() + offset, size,
856                                 GetByteOrder(), GetAddressByteSize());
857       return;
858     }
859   } else {
860     error.SetErrorToGenericError();
861     error.SetErrorString("Couldn't get memory data: its size was zero");
862     return;
863   }
864 }
865