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