1 //===-- AppleObjCClassDescriptorV2.h ----------------------------*- 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 #ifndef LLDB_SOURCE_PLUGINS_LANGUAGERUNTIME_OBJC_APPLEOBJCRUNTIME_APPLEOBJCCLASSDESCRIPTORV2_H
10 #define LLDB_SOURCE_PLUGINS_LANGUAGERUNTIME_OBJC_APPLEOBJCRUNTIME_APPLEOBJCCLASSDESCRIPTORV2_H
11 
12 #include <mutex>
13 
14 #include "AppleObjCRuntimeV2.h"
15 #include "lldb/lldb-enumerations.h"
16 #include "lldb/lldb-private.h"
17 
18 #include "Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h"
19 
20 namespace lldb_private {
21 
22 class ClassDescriptorV2 : public ObjCLanguageRuntime::ClassDescriptor {
23 public:
24   friend class lldb_private::AppleObjCRuntimeV2;
25 
26   ~ClassDescriptorV2() override = default;
27 
28   ConstString GetClassName() override;
29 
30   ObjCLanguageRuntime::ClassDescriptorSP GetSuperclass() override;
31 
32   ObjCLanguageRuntime::ClassDescriptorSP GetMetaclass() const override;
33 
34   bool IsValid() override {
35     return true; // any Objective-C v2 runtime class descriptor we vend is valid
36   }
37 
38   lldb::LanguageType GetImplementationLanguage() const override;
39 
40   // a custom descriptor is used for tagged pointers
41   bool GetTaggedPointerInfo(uint64_t *info_bits = nullptr,
42                             uint64_t *value_bits = nullptr,
43                             uint64_t *payload = nullptr) override {
44     return false;
45   }
46 
47   bool GetTaggedPointerInfoSigned(uint64_t *info_bits = nullptr,
48                                   int64_t *value_bits = nullptr,
49                                   uint64_t *payload = nullptr) override {
50     return false;
51   }
52 
53   uint64_t GetInstanceSize() override;
54 
55   ObjCLanguageRuntime::ObjCISA GetISA() override { return m_objc_class_ptr; }
56 
57   bool Describe(
58       std::function<void(ObjCLanguageRuntime::ObjCISA)> const &superclass_func,
59       std::function<bool(const char *, const char *)> const
60           &instance_method_func,
61       std::function<bool(const char *, const char *)> const &class_method_func,
62       std::function<bool(const char *, const char *, lldb::addr_t,
63                          uint64_t)> const &ivar_func) const override;
64 
65   size_t GetNumIVars() override {
66     GetIVarInformation();
67     return m_ivars_storage.size();
68   }
69 
70   iVarDescriptor GetIVarAtIndex(size_t idx) override {
71     if (idx >= GetNumIVars())
72       return iVarDescriptor();
73     return m_ivars_storage[idx];
74   }
75 
76 protected:
77   void GetIVarInformation();
78 
79 private:
80   static const uint32_t RW_REALIZED = (1 << 31);
81 
82   struct objc_class_t {
83     ObjCLanguageRuntime::ObjCISA m_isa = 0; // The class's metaclass.
84     ObjCLanguageRuntime::ObjCISA m_superclass = 0;
85     lldb::addr_t m_cache_ptr = 0;
86     lldb::addr_t m_vtable_ptr = 0;
87     lldb::addr_t m_data_ptr = 0;
88     uint8_t m_flags = 0;
89 
90     objc_class_t() = default;
91 
92     void Clear() {
93       m_isa = 0;
94       m_superclass = 0;
95       m_cache_ptr = 0;
96       m_vtable_ptr = 0;
97       m_data_ptr = 0;
98       m_flags = 0;
99     }
100 
101     bool Read(Process *process, lldb::addr_t addr);
102   };
103 
104   struct class_ro_t {
105     uint32_t m_flags;
106     uint32_t m_instanceStart;
107     uint32_t m_instanceSize;
108     uint32_t m_reserved;
109 
110     lldb::addr_t m_ivarLayout_ptr;
111     lldb::addr_t m_name_ptr;
112     lldb::addr_t m_baseMethods_ptr;
113     lldb::addr_t m_baseProtocols_ptr;
114     lldb::addr_t m_ivars_ptr;
115 
116     lldb::addr_t m_weakIvarLayout_ptr;
117     lldb::addr_t m_baseProperties_ptr;
118 
119     std::string m_name;
120 
121     bool Read(Process *process, lldb::addr_t addr);
122   };
123 
124   struct class_rw_t {
125     uint32_t m_flags;
126     uint32_t m_version;
127 
128     lldb::addr_t m_ro_ptr;
129     union {
130       lldb::addr_t m_method_list_ptr;
131       lldb::addr_t m_method_lists_ptr;
132     };
133     lldb::addr_t m_properties_ptr;
134     lldb::addr_t m_protocols_ptr;
135 
136     ObjCLanguageRuntime::ObjCISA m_firstSubclass;
137     ObjCLanguageRuntime::ObjCISA m_nextSiblingClass;
138 
139     bool Read(Process *process, lldb::addr_t addr);
140   };
141 
142   struct method_list_t {
143     uint16_t m_entsize;
144     bool m_is_small;
145     bool m_has_direct_selector;
146     uint32_t m_count;
147     lldb::addr_t m_first_ptr;
148 
149     bool Read(Process *process, lldb::addr_t addr);
150   };
151 
152   std::optional<method_list_t>
153   GetMethodList(Process *process, lldb::addr_t method_list_ptr) const;
154 
155   struct method_t {
156     lldb::addr_t m_name_ptr;
157     lldb::addr_t m_types_ptr;
158     lldb::addr_t m_imp_ptr;
159 
160     std::string m_name;
161     std::string m_types;
162 
163     static size_t GetSize(Process *process, bool is_small) {
164       size_t field_size;
165       if (is_small)
166         field_size = 4; // uint32_t relative indirect fields
167       else
168         field_size = process->GetAddressByteSize();
169 
170       return field_size    // SEL name;
171              + field_size  // const char *types;
172              + field_size; // IMP imp;
173     }
174 
175     bool Read(Process *process, lldb::addr_t addr,
176               lldb::addr_t relative_method_lists_base_addr, bool, bool);
177   };
178 
179   struct ivar_list_t {
180     uint32_t m_entsize;
181     uint32_t m_count;
182     lldb::addr_t m_first_ptr;
183 
184     bool Read(Process *process, lldb::addr_t addr);
185   };
186 
187   struct ivar_t {
188     lldb::addr_t m_offset_ptr;
189     lldb::addr_t m_name_ptr;
190     lldb::addr_t m_type_ptr;
191     uint32_t m_alignment;
192     uint32_t m_size;
193 
194     std::string m_name;
195     std::string m_type;
196 
197     static size_t GetSize(Process *process) {
198       size_t ptr_size = process->GetAddressByteSize();
199 
200       return ptr_size            // uintptr_t *offset;
201              + ptr_size          // const char *name;
202              + ptr_size          // const char *type;
203              + sizeof(uint32_t)  // uint32_t alignment;
204              + sizeof(uint32_t); // uint32_t size;
205     }
206 
207     bool Read(Process *process, lldb::addr_t addr);
208   };
209 
210   struct relative_list_entry_t {
211     uint16_t m_image_index;
212     int64_t m_list_offset;
213 
214     bool Read(Process *process, lldb::addr_t addr);
215   };
216 
217   struct relative_list_list_t {
218     uint32_t m_entsize;
219     uint32_t m_count;
220     lldb::addr_t m_first_ptr;
221 
222     bool Read(Process *process, lldb::addr_t addr);
223   };
224 
225   class iVarsStorage {
226   public:
227     iVarsStorage();
228 
229     size_t size();
230 
231     iVarDescriptor &operator[](size_t idx);
232 
233     void fill(AppleObjCRuntimeV2 &runtime, ClassDescriptorV2 &descriptor);
234 
235   private:
236     bool m_filled = false;
237     std::vector<iVarDescriptor> m_ivars;
238     std::recursive_mutex m_mutex;
239   };
240 
241   // The constructor should only be invoked by the runtime as it builds its
242   // caches
243   // or populates them.  A ClassDescriptorV2 should only ever exist in a cache.
244   ClassDescriptorV2(AppleObjCRuntimeV2 &runtime,
245                     ObjCLanguageRuntime::ObjCISA isa, const char *name)
246       : m_runtime(runtime), m_objc_class_ptr(isa), m_name(name),
247         m_ivars_storage(), m_image_to_method_lists(), m_last_version_updated() {
248   }
249 
250   bool Read_objc_class(Process *process,
251                        std::unique_ptr<objc_class_t> &objc_class) const;
252 
253   bool Read_class_row(Process *process, const objc_class_t &objc_class,
254                       std::unique_ptr<class_ro_t> &class_ro,
255                       std::unique_ptr<class_rw_t> &class_rw) const;
256 
257   bool ProcessMethodList(std::function<bool(const char *, const char *)> const
258                              &instance_method_func,
259                          method_list_t &method_list) const;
260 
261   bool ProcessRelativeMethodLists(
262       std::function<bool(const char *, const char *)> const
263           &instance_method_func,
264       lldb::addr_t relative_method_list_ptr) const;
265 
266   AppleObjCRuntimeV2
267       &m_runtime; // The runtime, so we can read information lazily.
268   lldb::addr_t m_objc_class_ptr; // The address of the objc_class_t.  (I.e.,
269                                  // objects of this class type have this as
270                                  // their ISA)
271   ConstString m_name;            // May be NULL
272   iVarsStorage m_ivars_storage;
273 
274   mutable std::map<uint16_t, std::vector<method_list_t>>
275       m_image_to_method_lists;
276   mutable std::optional<uint64_t> m_last_version_updated;
277 };
278 
279 // tagged pointer descriptor
280 class ClassDescriptorV2Tagged : public ObjCLanguageRuntime::ClassDescriptor {
281 public:
282   ClassDescriptorV2Tagged(ConstString class_name, uint64_t payload) {
283     m_name = class_name;
284     if (!m_name) {
285       m_valid = false;
286       return;
287     }
288     m_valid = true;
289     m_payload = payload;
290     m_info_bits = (m_payload & 0xF0ULL) >> 4;
291     m_value_bits = (m_payload & ~0x0000000000000000FFULL) >> 8;
292   }
293 
294   ClassDescriptorV2Tagged(
295       ObjCLanguageRuntime::ClassDescriptorSP actual_class_sp,
296       uint64_t u_payload, int64_t s_payload) {
297     if (!actual_class_sp) {
298       m_valid = false;
299       return;
300     }
301     m_name = actual_class_sp->GetClassName();
302     if (!m_name) {
303       m_valid = false;
304       return;
305     }
306     m_valid = true;
307     m_payload = u_payload;
308     m_info_bits = (m_payload & 0x0FULL);
309     m_value_bits = (m_payload & ~0x0FULL) >> 4;
310     m_value_bits_signed = (s_payload & ~0x0FLL) >> 4;
311   }
312 
313   ~ClassDescriptorV2Tagged() override = default;
314 
315   ConstString GetClassName() override { return m_name; }
316 
317   ObjCLanguageRuntime::ClassDescriptorSP GetSuperclass() override {
318     // tagged pointers can represent a class that has a superclass, but since
319     // that information is not
320     // stored in the object itself, we would have to query the runtime to
321     // discover the hierarchy
322     // for the time being, we skip this step in the interest of static discovery
323     return ObjCLanguageRuntime::ClassDescriptorSP();
324   }
325 
326   ObjCLanguageRuntime::ClassDescriptorSP GetMetaclass() const override {
327     return ObjCLanguageRuntime::ClassDescriptorSP();
328   }
329 
330   bool IsValid() override { return m_valid; }
331 
332   bool IsKVO() override {
333     return false; // tagged pointers are not KVO'ed
334   }
335 
336   bool IsCFType() override {
337     return false; // tagged pointers are not CF objects
338   }
339 
340   bool GetTaggedPointerInfo(uint64_t *info_bits = nullptr,
341                             uint64_t *value_bits = nullptr,
342                             uint64_t *payload = nullptr) override {
343     if (info_bits)
344       *info_bits = GetInfoBits();
345     if (value_bits)
346       *value_bits = GetValueBits();
347     if (payload)
348       *payload = GetPayload();
349     return true;
350   }
351 
352   bool GetTaggedPointerInfoSigned(uint64_t *info_bits = nullptr,
353                                   int64_t *value_bits = nullptr,
354                                   uint64_t *payload = nullptr) override {
355     if (info_bits)
356       *info_bits = GetInfoBits();
357     if (value_bits)
358       *value_bits = GetValueBitsSigned();
359     if (payload)
360       *payload = GetPayload();
361     return true;
362   }
363 
364   uint64_t GetInstanceSize() override {
365     return (IsValid() ? m_pointer_size : 0);
366   }
367 
368   ObjCLanguageRuntime::ObjCISA GetISA() override {
369     return 0; // tagged pointers have no ISA
370   }
371 
372   // these calls are not part of any formal tagged pointers specification
373   virtual uint64_t GetValueBits() { return (IsValid() ? m_value_bits : 0); }
374 
375   virtual int64_t GetValueBitsSigned() {
376     return (IsValid() ? m_value_bits_signed : 0);
377   }
378 
379   virtual uint64_t GetInfoBits() { return (IsValid() ? m_info_bits : 0); }
380 
381   virtual uint64_t GetPayload() { return (IsValid() ? m_payload : 0); }
382 
383 private:
384   ConstString m_name;
385   uint8_t m_pointer_size = 0;
386   bool m_valid = false;
387   uint64_t m_info_bits = 0;
388   uint64_t m_value_bits = 0;
389   int64_t m_value_bits_signed = 0;
390   uint64_t m_payload = 0;
391 };
392 
393 } // namespace lldb_private
394 
395 #endif // LLDB_SOURCE_PLUGINS_LANGUAGERUNTIME_OBJC_APPLEOBJCRUNTIME_APPLEOBJCCLASSDESCRIPTORV2_H
396