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

source code of lldb/source/Plugins/JITLoader/GDB/JITLoaderGDB.cpp