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 // - creating weak aliases to default implementation imported from asan dll.
18 // - forwarding the detect_stack_use_after_return runtime option
19 // - working around deficiencies of the MD runtime
20 // - installing a custom SEH handler
22 //===----------------------------------------------------------------------===//
24 #ifdef SANITIZER_DYNAMIC_RUNTIME_THUNK
25 #define SANITIZER_IMPORT_INTERFACE 1
26 #include "sanitizer_common/sanitizer_win_defs.h"
27 #define WIN32_LEAN_AND_MEAN
30 // Define weak alias for all weak functions imported from asan dll.
31 #define INTERFACE_FUNCTION(Name)
32 #define INTERFACE_WEAK_FUNCTION(Name) WIN_WEAK_IMPORT_DEF(Name)
33 #include "asan_interface.inc"
35 // First, declare CRT sections we'll be using in this file
36 #pragma section(".CRT$XIB", long, read) // NOLINT
37 #pragma section(".CRT$XID", long, read) // NOLINT
38 #pragma section(".CRT$XCAB", long, read) // NOLINT
39 #pragma section(".CRT$XTW", long, read) // NOLINT
40 #pragma section(".CRT$XTY", long, read) // NOLINT
41 #pragma section(".CRT$XLAB", long, read) // NOLINT
43 ////////////////////////////////////////////////////////////////////////////////
44 // Define a copy of __asan_option_detect_stack_use_after_return that should be
45 // used when linking an MD runtime with a set of object files on Windows.
47 // The ASan MD runtime dllexports '__asan_option_detect_stack_use_after_return',
48 // so normally we would just dllimport it. Unfortunately, the dllimport
49 // attribute adds __imp_ prefix to the symbol name of a variable.
50 // Since in general we don't know if a given TU is going to be used
51 // with a MT or MD runtime and we don't want to use ugly __imp_ names on Windows
52 // just to work around this issue, let's clone the variable that is constant
53 // after initialization anyways.
55 __declspec(dllimport) int __asan_should_detect_stack_use_after_return();
56 int __asan_option_detect_stack_use_after_return;
58 __declspec(dllimport) void* __asan_get_shadow_memory_dynamic_address();
59 void* __asan_shadow_memory_dynamic_address;
62 static int InitializeClonedVariables() {
63 __asan_option_detect_stack_use_after_return =
64 __asan_should_detect_stack_use_after_return();
65 __asan_shadow_memory_dynamic_address =
66 __asan_get_shadow_memory_dynamic_address();
70 static void NTAPI asan_thread_init(void *mod, unsigned long reason,
72 if (reason == DLL_PROCESS_ATTACH) InitializeClonedVariables();
75 // Our cloned variables must be initialized before C/C++ constructors. If TLS
76 // is used, our .CRT$XLAB initializer will run first. If not, our .CRT$XIB
77 // initializer is needed as a backup.
78 __declspec(allocate(".CRT$XIB")) int (*__asan_initialize_cloned_variables)() =
79 InitializeClonedVariables;
80 __declspec(allocate(".CRT$XLAB")) void (NTAPI *__asan_tls_init)(void *,
81 unsigned long, void *) = asan_thread_init;
83 ////////////////////////////////////////////////////////////////////////////////
84 // For some reason, the MD CRT doesn't call the C/C++ terminators during on DLL
85 // unload or on exit. ASan relies on LLVM global_dtors to call
86 // __asan_unregister_globals on these events, which unfortunately doesn't work
87 // with the MD runtime, see PR22545 for the details.
88 // To work around this, for each DLL we schedule a call to UnregisterGlobals
89 // using atexit() that calls a small subset of C terminators
90 // where LLVM global_dtors is placed. Fingers crossed, no other C terminators
92 extern "C" int __cdecl atexit(void (__cdecl *f)(void));
93 extern "C" void __cdecl _initterm(void *a, void *b);
96 __declspec(allocate(".CRT$XTW")) void* before_global_dtors = 0;
97 __declspec(allocate(".CRT$XTY")) void* after_global_dtors = 0;
99 void UnregisterGlobals() {
100 _initterm(&before_global_dtors, &after_global_dtors);
103 int ScheduleUnregisterGlobals() {
104 return atexit(UnregisterGlobals);
108 // We need to call 'atexit(UnregisterGlobals);' as early as possible, but after
109 // atexit() is initialized (.CRT$XIC). As this is executed before C++
110 // initializers (think ctors for globals), UnregisterGlobals gets executed after
111 // dtors for C++ globals.
112 __declspec(allocate(".CRT$XID"))
113 int (*__asan_schedule_unregister_globals)() = ScheduleUnregisterGlobals;
115 ////////////////////////////////////////////////////////////////////////////////
116 // ASan SEH handling.
117 // We need to set the ASan-specific SEH handler at the end of CRT initialization
118 // of each module (see also asan_win.cc).
120 __declspec(dllimport) int __asan_set_seh_filter();
121 static int SetSEHFilter() { return __asan_set_seh_filter(); }
123 // Unfortunately, putting a pointer to __asan_set_seh_filter into
124 // __asan_intercept_seh gets optimized out, so we have to use an extra function.
125 __declspec(allocate(".CRT$XCAB")) int (*__asan_seh_interceptor)() =
129 WIN_FORCE_LINK(__asan_dso_reg_hook)
131 #endif // SANITIZER_DYNAMIC_RUNTIME_THUNK