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      1 //===-- sanitizer_symbolizer.h ----------------------------------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // Symbolizer is used by sanitizers to map instruction address to a location in
     11 // source code at run-time. Symbolizer either uses __sanitizer_symbolize_*
     12 // defined in the program, or (if they are missing) tries to find and
     13 // launch "llvm-symbolizer" commandline tool in a separate process and
     14 // communicate with it.
     15 //
     16 // Generally we should try to avoid calling system library functions during
     17 // symbolization (and use their replacements from sanitizer_libc.h instead).
     18 //===----------------------------------------------------------------------===//
     19 #ifndef SANITIZER_SYMBOLIZER_H
     20 #define SANITIZER_SYMBOLIZER_H
     21 
     22 #include "sanitizer_common.h"
     23 #include "sanitizer_mutex.h"
     24 
     25 namespace __sanitizer {
     26 
     27 struct AddressInfo {
     28   // Owns all the string members. Storage for them is
     29   // (de)allocated using sanitizer internal allocator.
     30   uptr address;
     31 
     32   char *module;
     33   uptr module_offset;
     34 
     35   static const uptr kUnknown = ~(uptr)0;
     36   char *function;
     37   uptr function_offset;
     38 
     39   char *file;
     40   int line;
     41   int column;
     42 
     43   AddressInfo();
     44   // Deletes all strings and resets all fields.
     45   void Clear();
     46   void FillModuleInfo(const char *mod_name, uptr mod_offset);
     47 };
     48 
     49 // Linked list of symbolized frames (each frame is described by AddressInfo).
     50 struct SymbolizedStack {
     51   SymbolizedStack *next;
     52   AddressInfo info;
     53   static SymbolizedStack *New(uptr addr);
     54   // Deletes current, and all subsequent frames in the linked list.
     55   // The object cannot be accessed after the call to this function.
     56   void ClearAll();
     57 
     58  private:
     59   SymbolizedStack();
     60 };
     61 
     62 // For now, DataInfo is used to describe global variable.
     63 struct DataInfo {
     64   // Owns all the string members. Storage for them is
     65   // (de)allocated using sanitizer internal allocator.
     66   char *module;
     67   uptr module_offset;
     68   char *name;
     69   uptr start;
     70   uptr size;
     71 
     72   DataInfo();
     73   void Clear();
     74 };
     75 
     76 class SymbolizerTool;
     77 
     78 class Symbolizer final {
     79  public:
     80   /// Initialize and return platform-specific implementation of symbolizer
     81   /// (if it wasn't already initialized).
     82   static Symbolizer *GetOrInit();
     83   // Returns a list of symbolized frames for a given address (containing
     84   // all inlined functions, if necessary).
     85   SymbolizedStack *SymbolizePC(uptr address);
     86   bool SymbolizeData(uptr address, DataInfo *info);
     87 
     88   // The module names Symbolizer returns are stable and unique for every given
     89   // module.  It is safe to store and compare them as pointers.
     90   bool GetModuleNameAndOffsetForPC(uptr pc, const char **module_name,
     91                                    uptr *module_address);
     92   const char *GetModuleNameForPc(uptr pc) {
     93     const char *module_name = nullptr;
     94     uptr unused;
     95     if (GetModuleNameAndOffsetForPC(pc, &module_name, &unused))
     96       return module_name;
     97     return nullptr;
     98   }
     99 
    100   // Release internal caches (if any).
    101   void Flush();
    102   // Attempts to demangle the provided C++ mangled name.
    103   const char *Demangle(const char *name);
    104   void PrepareForSandboxing();
    105 
    106   // Allow user to install hooks that would be called before/after Symbolizer
    107   // does the actual file/line info fetching. Specific sanitizers may need this
    108   // to distinguish system library calls made in user code from calls made
    109   // during in-process symbolization.
    110   typedef void (*StartSymbolizationHook)();
    111   typedef void (*EndSymbolizationHook)();
    112   // May be called at most once.
    113   void AddHooks(StartSymbolizationHook start_hook,
    114                 EndSymbolizationHook end_hook);
    115 
    116  private:
    117   // GetModuleNameAndOffsetForPC has to return a string to the caller.
    118   // Since the corresponding module might get unloaded later, we should create
    119   // our owned copies of the strings that we can safely return.
    120   // ModuleNameOwner does not provide any synchronization, thus calls to
    121   // its method should be protected by |mu_|.
    122   class ModuleNameOwner {
    123    public:
    124     explicit ModuleNameOwner(BlockingMutex *synchronized_by)
    125         : storage_(kInitialCapacity), last_match_(nullptr),
    126           mu_(synchronized_by) {}
    127     const char *GetOwnedCopy(const char *str);
    128 
    129    private:
    130     static const uptr kInitialCapacity = 1000;
    131     InternalMmapVector<const char*> storage_;
    132     const char *last_match_;
    133 
    134     BlockingMutex *mu_;
    135   } module_names_;
    136 
    137   /// Platform-specific function for creating a Symbolizer object.
    138   static Symbolizer *PlatformInit();
    139 
    140   bool FindModuleNameAndOffsetForAddress(uptr address, const char **module_name,
    141                                          uptr *module_offset);
    142   LoadedModule *FindModuleForAddress(uptr address);
    143   LoadedModule modules_[kMaxNumberOfModules];
    144   uptr n_modules_;
    145   // If stale, need to reload the modules before looking up addresses.
    146   bool modules_fresh_;
    147 
    148   // Platform-specific default demangler, must not return nullptr.
    149   const char *PlatformDemangle(const char *name);
    150   void PlatformPrepareForSandboxing();
    151 
    152   static Symbolizer *symbolizer_;
    153   static StaticSpinMutex init_mu_;
    154 
    155   // Mutex locked from public methods of |Symbolizer|, so that the internals
    156   // (including individual symbolizer tools and platform-specific methods) are
    157   // always synchronized.
    158   BlockingMutex mu_;
    159 
    160   typedef IntrusiveList<SymbolizerTool>::Iterator Iterator;
    161   IntrusiveList<SymbolizerTool> tools_;
    162 
    163   explicit Symbolizer(IntrusiveList<SymbolizerTool> tools);
    164 
    165   static LowLevelAllocator symbolizer_allocator_;
    166 
    167   StartSymbolizationHook start_hook_;
    168   EndSymbolizationHook end_hook_;
    169   class SymbolizerScope {
    170    public:
    171     explicit SymbolizerScope(const Symbolizer *sym);
    172     ~SymbolizerScope();
    173    private:
    174     const Symbolizer *sym_;
    175   };
    176 };
    177 
    178 }  // namespace __sanitizer
    179 
    180 #endif  // SANITIZER_SYMBOLIZER_H
    181