src/compiler-rt/lib/asan/asan_win_dynamic_runtime_thunk.cc

   1 //===-- asan_win_uar_thunk.cc ---------------------------------------------===//
   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 // This file is a part of AddressSanitizer, an address sanity checker.
  11 //
  12 // This file defines things that need to be present in the application modules
  13 // to interact with the ASan DLL runtime correctly and can't be implemented
  14 // using the default "import library" generated when linking the DLL RTL.
  15 //
  16 // This includes:
  17 //  - forwarding the detect_stack_use_after_return runtime option
  18 //  - working around deficiencies of the MD runtime
  19 //  - installing a custom SEH handlerx
  20 //
  21 //===----------------------------------------------------------------------===//
  22
  23 // Only compile this code when buidling asan_dynamic_runtime_thunk.lib
  24 // Using #ifdef rather than relying on Makefiles etc.
  25 // simplifies the build procedure.
  26 #ifdef ASAN_DYNAMIC_RUNTIME_THUNK
  27 #define WIN32_LEAN_AND_MEAN
  28 #include <windows.h>
  29
  30 // First, declare CRT sections we'll be using in this file
  31 #pragma section(".CRT$XID", long, read)  // NOLINT
  32 #pragma section(".CRT$XCAB", long, read)  // NOLINT
  33 #pragma section(".CRT$XTW", long, read)  // NOLINT
  34 #pragma section(".CRT$XTY", long, read)  // NOLINT
  35
  36 ////////////////////////////////////////////////////////////////////////////////
  37 // Define a copy of __asan_option_detect_stack_use_after_return that should be
  38 // used when linking an MD runtime with a set of object files on Windows.
  39 //
  40 // The ASan MD runtime dllexports '__asan_option_detect_stack_use_after_return',
  41 // so normally we would just dllimport it.  Unfortunately, the dllimport
  42 // attribute adds __imp_ prefix to the symbol name of a variable.
  43 // Since in general we don't know if a given TU is going to be used
  44 // with a MT or MD runtime and we don't want to use ugly __imp_ names on Windows
  45 // just to work around this issue, let's clone the a variable that is
  46 // constant after initialization anyways.
  47 extern "C" {
  48 __declspec(dllimport) int __asan_should_detect_stack_use_after_return();
  49 int __asan_option_detect_stack_use_after_return =
  50     __asan_should_detect_stack_use_after_return();
  51 }
  52
  53 ////////////////////////////////////////////////////////////////////////////////
  54 // For some reason, the MD CRT doesn't call the C/C++ terminators during on DLL
  55 // unload or on exit.  ASan relies on LLVM global_dtors to call
  56 // __asan_unregister_globals on these events, which unfortunately doesn't work
  57 // with the MD runtime, see PR22545 for the details.
  58 // To work around this, for each DLL we schedule a call to UnregisterGlobals
  59 // using atexit() that calls a small subset of C terminators
  60 // where LLVM global_dtors is placed.  Fingers crossed, no other C terminators
  61 // are there.
  62 extern "C" int __cdecl atexit(void (__cdecl *f)(void));
  63 extern "C" void __cdecl _initterm(void *a, void *b);
  64
  65 namespace {
  66 __declspec(allocate(".CRT$XTW")) void* before_global_dtors = 0;
  67 __declspec(allocate(".CRT$XTY")) void* after_global_dtors = 0;
  68
  69 void UnregisterGlobals() {
  70   _initterm(&before_global_dtors, &after_global_dtors);
  71 }
  72
  73 int ScheduleUnregisterGlobals() {
  74   return atexit(UnregisterGlobals);
  75 }
  76
  77 // We need to call 'atexit(UnregisterGlobals);' as early as possible, but after
  78 // atexit() is initialized (.CRT$XIC).  As this is executed before C++
  79 // initializers (think ctors for globals), UnregisterGlobals gets executed after
  80 // dtors for C++ globals.
  81 __declspec(allocate(".CRT$XID"))
  82 int (*__asan_schedule_unregister_globals)() = ScheduleUnregisterGlobals;
  83
  84 }  // namespace
  85
  86 ////////////////////////////////////////////////////////////////////////////////
  87 // ASan SEH handling.
  88 // We need to set the ASan-specific SEH handler at the end of CRT initialization
  89 // of each module (see also asan_win.cc).
  90 extern "C" {
  91 __declspec(dllimport) int __asan_set_seh_filter();
  92 static int SetSEHFilter() { return __asan_set_seh_filter(); }
  93
  94 // Unfortunately, putting a pointer to __asan_set_seh_filter into
  95 // __asan_intercept_seh gets optimized out, so we have to use an extra function.
  96 __declspec(allocate(".CRT$XCAB")) int (*__asan_seh_interceptor)() =
  97     SetSEHFilter;
  98 }
  99
 100 #endif // ASAN_DYNAMIC_RUNTIME_THUNK