1 //===-- asan_win_dynamic_runtime_thunk.cc ---------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of AddressSanitizer, an address sanity checker.
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.
17 // - forwarding the detect_stack_use_after_return runtime option
18 // - working around deficiencies of the MD runtime
19 // - installing a custom SEH handler
21 //===----------------------------------------------------------------------===//
23 // Only compile this code when building 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 #include "asan_globals_win.h"
28 #define WIN32_LEAN_AND_MEAN
31 // First, declare CRT sections we'll be using in this file
32 #pragma section(".CRT$XIB", long, read) // NOLINT
33 #pragma section(".CRT$XID", long, read) // NOLINT
34 #pragma section(".CRT$XCAB", long, read) // NOLINT
35 #pragma section(".CRT$XTW", long, read) // NOLINT
36 #pragma section(".CRT$XTY", long, read) // NOLINT
37 #pragma section(".CRT$XLAB", long, read) // NOLINT
39 ////////////////////////////////////////////////////////////////////////////////
40 // Define a copy of __asan_option_detect_stack_use_after_return that should be
41 // used when linking an MD runtime with a set of object files on Windows.
43 // The ASan MD runtime dllexports '__asan_option_detect_stack_use_after_return',
44 // so normally we would just dllimport it. Unfortunately, the dllimport
45 // attribute adds __imp_ prefix to the symbol name of a variable.
46 // Since in general we don't know if a given TU is going to be used
47 // with a MT or MD runtime and we don't want to use ugly __imp_ names on Windows
48 // just to work around this issue, let's clone the variable that is constant
49 // after initialization anyways.
51 __declspec(dllimport) int __asan_should_detect_stack_use_after_return();
52 int __asan_option_detect_stack_use_after_return;
54 __declspec(dllimport) void* __asan_get_shadow_memory_dynamic_address();
55 void* __asan_shadow_memory_dynamic_address;
58 static int InitializeClonedVariables() {
59 __asan_option_detect_stack_use_after_return =
60 __asan_should_detect_stack_use_after_return();
61 __asan_shadow_memory_dynamic_address =
62 __asan_get_shadow_memory_dynamic_address();
66 static void NTAPI asan_thread_init(void *mod, unsigned long reason,
68 if (reason == DLL_PROCESS_ATTACH) InitializeClonedVariables();
71 // Our cloned variables must be initialized before C/C++ constructors. If TLS
72 // is used, our .CRT$XLAB initializer will run first. If not, our .CRT$XIB
73 // initializer is needed as a backup.
74 __declspec(allocate(".CRT$XIB")) int (*__asan_initialize_cloned_variables)() =
75 InitializeClonedVariables;
76 __declspec(allocate(".CRT$XLAB")) void (NTAPI *__asan_tls_init)(void *,
77 unsigned long, void *) = asan_thread_init;
79 ////////////////////////////////////////////////////////////////////////////////
80 // For some reason, the MD CRT doesn't call the C/C++ terminators during on DLL
81 // unload or on exit. ASan relies on LLVM global_dtors to call
82 // __asan_unregister_globals on these events, which unfortunately doesn't work
83 // with the MD runtime, see PR22545 for the details.
84 // To work around this, for each DLL we schedule a call to UnregisterGlobals
85 // using atexit() that calls a small subset of C terminators
86 // where LLVM global_dtors is placed. Fingers crossed, no other C terminators
88 extern "C" int __cdecl atexit(void (__cdecl *f)(void));
89 extern "C" void __cdecl _initterm(void *a, void *b);
92 __declspec(allocate(".CRT$XTW")) void* before_global_dtors = 0;
93 __declspec(allocate(".CRT$XTY")) void* after_global_dtors = 0;
95 void UnregisterGlobals() {
96 _initterm(&before_global_dtors, &after_global_dtors);
99 int ScheduleUnregisterGlobals() {
100 return atexit(UnregisterGlobals);
104 // We need to call 'atexit(UnregisterGlobals);' as early as possible, but after
105 // atexit() is initialized (.CRT$XIC). As this is executed before C++
106 // initializers (think ctors for globals), UnregisterGlobals gets executed after
107 // dtors for C++ globals.
108 __declspec(allocate(".CRT$XID"))
109 int (*__asan_schedule_unregister_globals)() = ScheduleUnregisterGlobals;
111 ////////////////////////////////////////////////////////////////////////////////
112 // ASan SEH handling.
113 // We need to set the ASan-specific SEH handler at the end of CRT initialization
114 // of each module (see also asan_win.cc).
116 __declspec(dllimport) int __asan_set_seh_filter();
117 static int SetSEHFilter() { return __asan_set_seh_filter(); }
119 // Unfortunately, putting a pointer to __asan_set_seh_filter into
120 // __asan_intercept_seh gets optimized out, so we have to use an extra function.
121 __declspec(allocate(".CRT$XCAB")) int (*__asan_seh_interceptor)() =
125 ASAN_LINK_GLOBALS_WIN()
127 #endif // ASAN_DYNAMIC_RUNTIME_THUNK