libsanitizer/asan/asan_win_dynamic_runtime_thunk.cc

   1 //===-- asan_win_uar_thunk.cc ---------------------------------------------===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is a part of AddressSanitizer, an address sanity checker.
   9 //
  10 // This file defines things that need to be present in the application modules
  11 // to interact with the ASan DLL runtime correctly and can't be implemented
  12 // using the default "import library" generated when linking the DLL RTL.
  13 //
  14 // This includes:
  15 //  - forwarding the detect_stack_use_after_return runtime option
  16 //  - working around deficiencies of the MD runtime
  17 //  - installing a custom SEH handlerx
  18 //
  19 //===----------------------------------------------------------------------===//
  20
  21 // Only compile this code when buidling asan_dynamic_runtime_thunk.lib
  22 // Using #ifdef rather than relying on Makefiles etc.
  23 // simplifies the build procedure.
  24 #ifdef ASAN_DYNAMIC_RUNTIME_THUNK
  25 #include <windows.h>
  26
  27 // First, declare CRT sections we'll be using in this file
  28 #pragma section(".CRT$XID", long, read)  // NOLINT
  29 #pragma section(".CRT$XIZ", long, read)  // NOLINT
  30 #pragma section(".CRT$XTW", long, read)  // NOLINT
  31 #pragma section(".CRT$XTY", long, read)  // NOLINT
  32
  33 ////////////////////////////////////////////////////////////////////////////////
  34 // Define a copy of __asan_option_detect_stack_use_after_return that should be
  35 // used when linking an MD runtime with a set of object files on Windows.
  36 //
  37 // The ASan MD runtime dllexports '__asan_option_detect_stack_use_after_return',
  38 // so normally we would just dllimport it.  Unfortunately, the dllimport
  39 // attribute adds __imp_ prefix to the symbol name of a variable.
  40 // Since in general we don't know if a given TU is going to be used
  41 // with a MT or MD runtime and we don't want to use ugly __imp_ names on Windows
  42 // just to work around this issue, let's clone the a variable that is
  43 // constant after initialization anyways.
  44 extern "C" {
  45 __declspec(dllimport) int __asan_should_detect_stack_use_after_return();
  46 int __asan_option_detect_stack_use_after_return =
  47     __asan_should_detect_stack_use_after_return();
  48 }
  49
  50 ////////////////////////////////////////////////////////////////////////////////
  51 // For some reason, the MD CRT doesn't call the C/C++ terminators during on DLL
  52 // unload or on exit.  ASan relies on LLVM global_dtors to call
  53 // __asan_unregister_globals on these events, which unfortunately doesn't work
  54 // with the MD runtime, see PR22545 for the details.
  55 // To work around this, for each DLL we schedule a call to UnregisterGlobals
  56 // using atexit() that calls a small subset of C terminators
  57 // where LLVM global_dtors is placed.  Fingers crossed, no other C terminators
  58 // are there.
  59 extern "C" void __cdecl _initterm(void *a, void *b);
  60
  61 namespace {
  62 __declspec(allocate(".CRT$XTW")) void* before_global_dtors = 0;
  63 __declspec(allocate(".CRT$XTY")) void* after_global_dtors = 0;
  64
  65 void UnregisterGlobals() {
  66   _initterm(&before_global_dtors, &after_global_dtors);
  67 }
  68
  69 int ScheduleUnregisterGlobals() {
  70   return atexit(UnregisterGlobals);
  71 }
  72
  73 // We need to call 'atexit(UnregisterGlobals);' as early as possible, but after
  74 // atexit() is initialized (.CRT$XIC).  As this is executed before C++
  75 // initializers (think ctors for globals), UnregisterGlobals gets executed after
  76 // dtors for C++ globals.
  77 __declspec(allocate(".CRT$XID"))
  78 int (*__asan_schedule_unregister_globals)() = ScheduleUnregisterGlobals;
  79
  80 }  // namespace
  81
  82 ////////////////////////////////////////////////////////////////////////////////
  83 // ASan SEH handling.
  84 // We need to set the ASan-specific SEH handler at the end of CRT initialization
  85 // of each module (see also asan_win.cc).
  86 extern "C" {
  87 __declspec(dllimport) int __asan_set_seh_filter();
  88 static int SetSEHFilter() { return __asan_set_seh_filter(); }
  89
  90 // Unfortunately, putting a pointer to __asan_set_seh_filter into
  91 // __asan_intercept_seh gets optimized out, so we have to use an extra function.
  92 __declspec(allocate(".CRT$XIZ")) int (*__asan_seh_interceptor)() = SetSEHFilter;
  93 }
  94
  95 #endif // ASAN_DYNAMIC_RUNTIME_THUNK