1 //===-- JITLoaderGDB.cpp ----------------------------------------*- C++ -*-===//
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 
10 #include "llvm/Support/MathExtras.h"
11 
12 #include "lldb/Breakpoint/Breakpoint.h"
13 #include "lldb/Core/Module.h"
14 #include "lldb/Core/ModuleSpec.h"
15 #include "lldb/Core/PluginManager.h"
16 #include "lldb/Core/Section.h"
17 #include "lldb/Interpreter/OptionValueProperties.h"
18 #include "lldb/Symbol/ObjectFile.h"
19 #include "lldb/Symbol/Symbol.h"
20 #include "lldb/Symbol/SymbolContext.h"
21 #include "lldb/Symbol/SymbolVendor.h"
22 #include "lldb/Target/Process.h"
23 #include "lldb/Target/SectionLoadList.h"
24 #include "lldb/Target/Target.h"
25 #include "lldb/Utility/DataBufferHeap.h"
26 #include "lldb/Utility/LLDBAssert.h"
27 #include "lldb/Utility/Log.h"
28 #include "lldb/Utility/StreamString.h"
29 
30 #include "JITLoaderGDB.h"
31 
32 #include <memory>
33 
34 using namespace lldb;
35 using namespace lldb_private;
36 
37 // Debug Interface Structures
38 enum jit_actions_t { JIT_NOACTION = 0, JIT_REGISTER_FN, JIT_UNREGISTER_FN };
39 
40 template <typename ptr_t> struct jit_code_entry {
41   ptr_t next_entry;   // pointer
42   ptr_t prev_entry;   // pointer
43   ptr_t symfile_addr; // pointer
44   uint64_t symfile_size;
45 };
46 
47 template <typename ptr_t> struct jit_descriptor {
48   uint32_t version;
49   uint32_t action_flag; // Values are jit_action_t
50   ptr_t relevant_entry; // pointer
51   ptr_t first_entry;    // pointer
52 };
53 
54 namespace {
55 
56 enum EnableJITLoaderGDB {
57   eEnableJITLoaderGDBDefault,
58   eEnableJITLoaderGDBOn,
59   eEnableJITLoaderGDBOff,
60 };
61 
62 static constexpr OptionEnumValueElement g_enable_jit_loader_gdb_enumerators[] = {
63     {eEnableJITLoaderGDBDefault, "default", "Enable JIT compilation interface "
64      "for all platforms except macOS"},
65     {eEnableJITLoaderGDBOn, "on", "Enable JIT compilation interface"},
66     {eEnableJITLoaderGDBOff, "off", "Disable JIT compilation interface"}
67  };
68 
69 static constexpr PropertyDefinition g_properties[] = {
70 #define LLDB_PROPERTIES_jitloadergdb
71 #include "Properties.inc"
72 };
73 
74 enum {
75 #define LLDB_PROPERTIES_jitloadergdb
76 #include "PropertiesEnum.inc"
77   ePropertyEnableJITBreakpoint
78 };
79 
80 class PluginProperties : public Properties {
81 public:
82   static ConstString GetSettingName() {
83     return JITLoaderGDB::GetPluginNameStatic();
84   }
85 
86   PluginProperties() {
87     m_collection_sp = std::make_shared<OptionValueProperties>(GetSettingName());
88     m_collection_sp->Initialize(g_properties);
89   }
90 
91   EnableJITLoaderGDB GetEnable() const {
92     return (EnableJITLoaderGDB)m_collection_sp->GetPropertyAtIndexAsEnumeration(
93         nullptr, ePropertyEnable,
94         g_properties[ePropertyEnable].default_uint_value);
95   }
96 };
97 
98 typedef std::shared_ptr<PluginProperties> JITLoaderGDBPropertiesSP;
99 
100 static const JITLoaderGDBPropertiesSP &GetGlobalPluginProperties() {
101   static const auto g_settings_sp(std::make_shared<PluginProperties>());
102   return g_settings_sp;
103 }
104 
105 template <typename ptr_t>
106 bool ReadJITEntry(const addr_t from_addr, Process *process,
107                   jit_code_entry<ptr_t> *entry) {
108   lldbassert(from_addr % sizeof(ptr_t) == 0);
109 
110   ArchSpec::Core core = process->GetTarget().GetArchitecture().GetCore();
111   bool i386_target = ArchSpec::kCore_x86_32_first <= core &&
112                      core <= ArchSpec::kCore_x86_32_last;
113   uint8_t uint64_align_bytes = i386_target ? 4 : 8;
114   const size_t data_byte_size =
115       llvm::alignTo(sizeof(ptr_t) * 3, uint64_align_bytes) + sizeof(uint64_t);
116 
117   Status error;
118   DataBufferHeap data(data_byte_size, 0);
119   size_t bytes_read = process->ReadMemory(from_addr, data.GetBytes(),
120                                           data.GetByteSize(), error);
121   if (bytes_read != data_byte_size || !error.Success())
122     return false;
123 
124   DataExtractor extractor(data.GetBytes(), data.GetByteSize(),
125                           process->GetByteOrder(), sizeof(ptr_t));
126   lldb::offset_t offset = 0;
127   entry->next_entry = extractor.GetPointer(&offset);
128   entry->prev_entry = extractor.GetPointer(&offset);
129   entry->symfile_addr = extractor.GetPointer(&offset);
130   offset = llvm::alignTo(offset, uint64_align_bytes);
131   entry->symfile_size = extractor.GetU64(&offset);
132 
133   return true;
134 }
135 
136 } // anonymous namespace end
137 
138 JITLoaderGDB::JITLoaderGDB(lldb_private::Process *process)
139     : JITLoader(process), m_jit_objects(),
140       m_jit_break_id(LLDB_INVALID_BREAK_ID),
141       m_jit_descriptor_addr(LLDB_INVALID_ADDRESS) {}
142 
143 JITLoaderGDB::~JITLoaderGDB() {
144   if (LLDB_BREAK_ID_IS_VALID(m_jit_break_id))
145     m_process->GetTarget().RemoveBreakpointByID(m_jit_break_id);
146 }
147 
148 void JITLoaderGDB::DebuggerInitialize(Debugger &debugger) {
149   if (!PluginManager::GetSettingForJITLoaderPlugin(
150           debugger, PluginProperties::GetSettingName())) {
151     const bool is_global_setting = true;
152     PluginManager::CreateSettingForJITLoaderPlugin(
153         debugger, GetGlobalPluginProperties()->GetValueProperties(),
154         ConstString("Properties for the JIT LoaderGDB plug-in."),
155         is_global_setting);
156   }
157 }
158 
159 void JITLoaderGDB::DidAttach() {
160   Target &target = m_process->GetTarget();
161   ModuleList &module_list = target.GetImages();
162   SetJITBreakpoint(module_list);
163 }
164 
165 void JITLoaderGDB::DidLaunch() {
166   Target &target = m_process->GetTarget();
167   ModuleList &module_list = target.GetImages();
168   SetJITBreakpoint(module_list);
169 }
170 
171 void JITLoaderGDB::ModulesDidLoad(ModuleList &module_list) {
172   if (!DidSetJITBreakpoint() && m_process->IsAlive())
173     SetJITBreakpoint(module_list);
174 }
175 
176 // Setup the JIT Breakpoint
177 void JITLoaderGDB::SetJITBreakpoint(lldb_private::ModuleList &module_list) {
178   if (DidSetJITBreakpoint())
179     return;
180 
181   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_JIT_LOADER));
182   LLDB_LOGF(log, "JITLoaderGDB::%s looking for JIT register hook",
183             __FUNCTION__);
184 
185   addr_t jit_addr = GetSymbolAddress(
186       module_list, ConstString("__jit_debug_register_code"), eSymbolTypeAny);
187   if (jit_addr == LLDB_INVALID_ADDRESS)
188     return;
189 
190   m_jit_descriptor_addr = GetSymbolAddress(
191       module_list, ConstString("__jit_debug_descriptor"), eSymbolTypeData);
192   if (m_jit_descriptor_addr == LLDB_INVALID_ADDRESS) {
193     LLDB_LOGF(log, "JITLoaderGDB::%s failed to find JIT descriptor address",
194               __FUNCTION__);
195     return;
196   }
197 
198   LLDB_LOGF(log, "JITLoaderGDB::%s setting JIT breakpoint", __FUNCTION__);
199 
200   Breakpoint *bp =
201       m_process->GetTarget().CreateBreakpoint(jit_addr, true, false).get();
202   bp->SetCallback(JITDebugBreakpointHit, this, true);
203   bp->SetBreakpointKind("jit-debug-register");
204   m_jit_break_id = bp->GetID();
205 
206   ReadJITDescriptor(true);
207 }
208 
209 bool JITLoaderGDB::JITDebugBreakpointHit(void *baton,
210                                          StoppointCallbackContext *context,
211                                          user_id_t break_id,
212                                          user_id_t break_loc_id) {
213   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_JIT_LOADER));
214   LLDB_LOGF(log, "JITLoaderGDB::%s hit JIT breakpoint", __FUNCTION__);
215   JITLoaderGDB *instance = static_cast<JITLoaderGDB *>(baton);
216   return instance->ReadJITDescriptor(false);
217 }
218 
219 static void updateSectionLoadAddress(const SectionList &section_list,
220                                      Target &target, uint64_t symbolfile_addr,
221                                      uint64_t symbolfile_size,
222                                      uint64_t &vmaddrheuristic,
223                                      uint64_t &min_addr, uint64_t &max_addr) {
224   const uint32_t num_sections = section_list.GetSize();
225   for (uint32_t i = 0; i < num_sections; ++i) {
226     SectionSP section_sp(section_list.GetSectionAtIndex(i));
227     if (section_sp) {
228       if (section_sp->IsFake()) {
229         uint64_t lower = (uint64_t)-1;
230         uint64_t upper = 0;
231         updateSectionLoadAddress(section_sp->GetChildren(), target,
232                                  symbolfile_addr, symbolfile_size,
233                                  vmaddrheuristic, lower, upper);
234         if (lower < min_addr)
235           min_addr = lower;
236         if (upper > max_addr)
237           max_addr = upper;
238         const lldb::addr_t slide_amount = lower - section_sp->GetFileAddress();
239         section_sp->Slide(slide_amount, false);
240         section_sp->GetChildren().Slide(-slide_amount, false);
241         section_sp->SetByteSize(upper - lower);
242       } else {
243         vmaddrheuristic += 2 << section_sp->GetLog2Align();
244         uint64_t lower;
245         if (section_sp->GetFileAddress() > vmaddrheuristic)
246           lower = section_sp->GetFileAddress();
247         else {
248           lower = symbolfile_addr + section_sp->GetFileOffset();
249           section_sp->SetFileAddress(symbolfile_addr +
250                                      section_sp->GetFileOffset());
251         }
252         target.SetSectionLoadAddress(section_sp, lower, true);
253         uint64_t upper = lower + section_sp->GetByteSize();
254         if (lower < min_addr)
255           min_addr = lower;
256         if (upper > max_addr)
257           max_addr = upper;
258         // This is an upper bound, but a good enough heuristic
259         vmaddrheuristic += section_sp->GetByteSize();
260       }
261     }
262   }
263 }
264 
265 bool JITLoaderGDB::ReadJITDescriptor(bool all_entries) {
266   if (m_process->GetTarget().GetArchitecture().GetAddressByteSize() == 8)
267     return ReadJITDescriptorImpl<uint64_t>(all_entries);
268   else
269     return ReadJITDescriptorImpl<uint32_t>(all_entries);
270 }
271 
272 template <typename ptr_t>
273 bool JITLoaderGDB::ReadJITDescriptorImpl(bool all_entries) {
274   if (m_jit_descriptor_addr == LLDB_INVALID_ADDRESS)
275     return false;
276 
277   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_JIT_LOADER));
278   Target &target = m_process->GetTarget();
279   ModuleList &module_list = target.GetImages();
280 
281   jit_descriptor<ptr_t> jit_desc;
282   const size_t jit_desc_size = sizeof(jit_desc);
283   Status error;
284   size_t bytes_read = m_process->DoReadMemory(m_jit_descriptor_addr, &jit_desc,
285                                               jit_desc_size, error);
286   if (bytes_read != jit_desc_size || !error.Success()) {
287     LLDB_LOGF(log, "JITLoaderGDB::%s failed to read JIT descriptor",
288               __FUNCTION__);
289     return false;
290   }
291 
292   jit_actions_t jit_action = (jit_actions_t)jit_desc.action_flag;
293   addr_t jit_relevant_entry = (addr_t)jit_desc.relevant_entry;
294   if (all_entries) {
295     jit_action = JIT_REGISTER_FN;
296     jit_relevant_entry = (addr_t)jit_desc.first_entry;
297   }
298 
299   while (jit_relevant_entry != 0) {
300     jit_code_entry<ptr_t> jit_entry;
301     if (!ReadJITEntry(jit_relevant_entry, m_process, &jit_entry)) {
302       LLDB_LOGF(log, "JITLoaderGDB::%s failed to read JIT entry at 0x%" PRIx64,
303                 __FUNCTION__, jit_relevant_entry);
304       return false;
305     }
306 
307     const addr_t &symbolfile_addr = (addr_t)jit_entry.symfile_addr;
308     const size_t &symbolfile_size = (size_t)jit_entry.symfile_size;
309     ModuleSP module_sp;
310 
311     if (jit_action == JIT_REGISTER_FN) {
312       LLDB_LOGF(log,
313                 "JITLoaderGDB::%s registering JIT entry at 0x%" PRIx64
314                 " (%" PRIu64 " bytes)",
315                 __FUNCTION__, symbolfile_addr, (uint64_t)symbolfile_size);
316 
317       char jit_name[64];
318       snprintf(jit_name, 64, "JIT(0x%" PRIx64 ")", symbolfile_addr);
319       module_sp = m_process->ReadModuleFromMemory(
320           FileSpec(jit_name), symbolfile_addr, symbolfile_size);
321 
322       if (module_sp && module_sp->GetObjectFile()) {
323         // Object formats (like ELF) have no representation for a JIT type.
324         // We will get it wrong, if we deduce it from the header.
325         module_sp->GetObjectFile()->SetType(ObjectFile::eTypeJIT);
326 
327         // load the symbol table right away
328         module_sp->GetObjectFile()->GetSymtab();
329 
330         m_jit_objects.insert(std::make_pair(symbolfile_addr, module_sp));
331         if (module_sp->GetObjectFile()->GetPluginName() ==
332             ConstString("mach-o")) {
333           ObjectFile *image_object_file = module_sp->GetObjectFile();
334           if (image_object_file) {
335             const SectionList *section_list =
336                 image_object_file->GetSectionList();
337             if (section_list) {
338               uint64_t vmaddrheuristic = 0;
339               uint64_t lower = (uint64_t)-1;
340               uint64_t upper = 0;
341               updateSectionLoadAddress(*section_list, target, symbolfile_addr,
342                                        symbolfile_size, vmaddrheuristic, lower,
343                                        upper);
344             }
345           }
346         } else {
347           bool changed = false;
348           module_sp->SetLoadAddress(target, 0, true, changed);
349         }
350 
351         module_list.AppendIfNeeded(module_sp);
352 
353         ModuleList module_list;
354         module_list.Append(module_sp);
355         target.ModulesDidLoad(module_list);
356       } else {
357         LLDB_LOGF(log,
358                   "JITLoaderGDB::%s failed to load module for "
359                   "JIT entry at 0x%" PRIx64,
360                   __FUNCTION__, symbolfile_addr);
361       }
362     } else if (jit_action == JIT_UNREGISTER_FN) {
363       LLDB_LOGF(log, "JITLoaderGDB::%s unregistering JIT entry at 0x%" PRIx64,
364                 __FUNCTION__, symbolfile_addr);
365 
366       JITObjectMap::iterator it = m_jit_objects.find(symbolfile_addr);
367       if (it != m_jit_objects.end()) {
368         module_sp = it->second;
369         ObjectFile *image_object_file = module_sp->GetObjectFile();
370         if (image_object_file) {
371           const SectionList *section_list = image_object_file->GetSectionList();
372           if (section_list) {
373             const uint32_t num_sections = section_list->GetSize();
374             for (uint32_t i = 0; i < num_sections; ++i) {
375               SectionSP section_sp(section_list->GetSectionAtIndex(i));
376               if (section_sp) {
377                 target.GetSectionLoadList().SetSectionUnloaded(section_sp);
378               }
379             }
380           }
381         }
382         module_list.Remove(module_sp);
383         m_jit_objects.erase(it);
384       }
385     } else if (jit_action == JIT_NOACTION) {
386       // Nothing to do
387     } else {
388       assert(false && "Unknown jit action");
389     }
390 
391     if (all_entries)
392       jit_relevant_entry = (addr_t)jit_entry.next_entry;
393     else
394       jit_relevant_entry = 0;
395   }
396 
397   return false; // Continue Running.
398 }
399 
400 // PluginInterface protocol
401 lldb_private::ConstString JITLoaderGDB::GetPluginNameStatic() {
402   static ConstString g_name("gdb");
403   return g_name;
404 }
405 
406 JITLoaderSP JITLoaderGDB::CreateInstance(Process *process, bool force) {
407   JITLoaderSP jit_loader_sp;
408   bool enable;
409   switch (GetGlobalPluginProperties()->GetEnable()) {
410     case EnableJITLoaderGDB::eEnableJITLoaderGDBOn:
411       enable = true;
412       break;
413     case EnableJITLoaderGDB::eEnableJITLoaderGDBOff:
414       enable = false;
415       break;
416     case EnableJITLoaderGDB::eEnableJITLoaderGDBDefault:
417       ArchSpec arch(process->GetTarget().GetArchitecture());
418       enable = arch.GetTriple().getVendor() != llvm::Triple::Apple;
419       break;
420   }
421   if (enable)
422     jit_loader_sp = std::make_shared<JITLoaderGDB>(process);
423   return jit_loader_sp;
424 }
425 
426 const char *JITLoaderGDB::GetPluginDescriptionStatic() {
427   return "JIT loader plug-in that watches for JIT events using the GDB "
428          "interface.";
429 }
430 
431 lldb_private::ConstString JITLoaderGDB::GetPluginName() {
432   return GetPluginNameStatic();
433 }
434 
435 uint32_t JITLoaderGDB::GetPluginVersion() { return 1; }
436 
437 void JITLoaderGDB::Initialize() {
438   PluginManager::RegisterPlugin(GetPluginNameStatic(),
439                                 GetPluginDescriptionStatic(), CreateInstance,
440                                 DebuggerInitialize);
441 }
442 
443 void JITLoaderGDB::Terminate() {
444   PluginManager::UnregisterPlugin(CreateInstance);
445 }
446 
447 bool JITLoaderGDB::DidSetJITBreakpoint() const {
448   return LLDB_BREAK_ID_IS_VALID(m_jit_break_id);
449 }
450 
451 addr_t JITLoaderGDB::GetSymbolAddress(ModuleList &module_list,
452                                       ConstString name,
453                                       SymbolType symbol_type) const {
454   SymbolContextList target_symbols;
455   Target &target = m_process->GetTarget();
456 
457   if (!module_list.FindSymbolsWithNameAndType(name, symbol_type,
458                                               target_symbols))
459     return LLDB_INVALID_ADDRESS;
460 
461   SymbolContext sym_ctx;
462   target_symbols.GetContextAtIndex(0, sym_ctx);
463 
464   const Address jit_descriptor_addr = sym_ctx.symbol->GetAddress();
465   if (!jit_descriptor_addr.IsValid())
466     return LLDB_INVALID_ADDRESS;
467 
468   const addr_t jit_addr = jit_descriptor_addr.GetLoadAddress(&target);
469   return jit_addr;
470 }
471