blob: f0b5ec9eef7f99db7b139cabc78e7ba24c72eeed [file] [log] [blame]
//===-- asan_win_dynamic_runtime_thunk.cpp --------------------------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This file is a part of AddressSanitizer, an address sanity checker.
// This file defines things that need to be present in the application modules
// to interact with the ASan DLL runtime correctly and can't be implemented
// using the default "import library" generated when linking the DLL RTL.
// This includes:
// - creating weak aliases to default implementation imported from asan dll.
// - forwarding the detect_stack_use_after_return runtime option
// - working around deficiencies of the MD runtime
// - installing a custom SEH handler
#include "sanitizer_common/sanitizer_win_defs.h"
#include <windows.h>
// Define weak alias for all weak functions imported from asan dll.
#include ""
// First, declare CRT sections we'll be using in this file
#pragma section(".CRT$XIB", long, read)
#pragma section(".CRT$XID", long, read)
#pragma section(".CRT$XCAB", long, read)
#pragma section(".CRT$XTW", long, read)
#pragma section(".CRT$XTY", long, read)
#pragma section(".CRT$XLAB", long, read)
// Define a copy of __asan_option_detect_stack_use_after_return that should be
// used when linking an MD runtime with a set of object files on Windows.
// The ASan MD runtime dllexports '__asan_option_detect_stack_use_after_return',
// so normally we would just dllimport it. Unfortunately, the dllimport
// attribute adds __imp_ prefix to the symbol name of a variable.
// Since in general we don't know if a given TU is going to be used
// with a MT or MD runtime and we don't want to use ugly __imp_ names on Windows
// just to work around this issue, let's clone the variable that is constant
// after initialization anyways.
extern "C" {
__declspec(dllimport) int __asan_should_detect_stack_use_after_return();
int __asan_option_detect_stack_use_after_return;
__declspec(dllimport) void* __asan_get_shadow_memory_dynamic_address();
void* __asan_shadow_memory_dynamic_address;
static int InitializeClonedVariables() {
__asan_option_detect_stack_use_after_return =
__asan_shadow_memory_dynamic_address =
return 0;
static void NTAPI asan_thread_init(void *mod, unsigned long reason,
void *reserved) {
if (reason == DLL_PROCESS_ATTACH) InitializeClonedVariables();
// Our cloned variables must be initialized before C/C++ constructors. If TLS
// is used, our .CRT$XLAB initializer will run first. If not, our .CRT$XIB
// initializer is needed as a backup.
__declspec(allocate(".CRT$XIB")) int (*__asan_initialize_cloned_variables)() =
__declspec(allocate(".CRT$XLAB")) void (NTAPI *__asan_tls_init)(void *,
unsigned long, void *) = asan_thread_init;
// For some reason, the MD CRT doesn't call the C/C++ terminators during on DLL
// unload or on exit. ASan relies on LLVM global_dtors to call
// __asan_unregister_globals on these events, which unfortunately doesn't work
// with the MD runtime, see PR22545 for the details.
// To work around this, for each DLL we schedule a call to UnregisterGlobals
// using atexit() that calls a small subset of C terminators
// where LLVM global_dtors is placed. Fingers crossed, no other C terminators
// are there.
extern "C" int __cdecl atexit(void (__cdecl *f)(void));
extern "C" void __cdecl _initterm(void *a, void *b);
namespace {
__declspec(allocate(".CRT$XTW")) void* before_global_dtors = 0;
__declspec(allocate(".CRT$XTY")) void* after_global_dtors = 0;
void UnregisterGlobals() {
_initterm(&before_global_dtors, &after_global_dtors);
int ScheduleUnregisterGlobals() {
return atexit(UnregisterGlobals);
} // namespace
// We need to call 'atexit(UnregisterGlobals);' as early as possible, but after
// atexit() is initialized (.CRT$XIC). As this is executed before C++
// initializers (think ctors for globals), UnregisterGlobals gets executed after
// dtors for C++ globals.
int (*__asan_schedule_unregister_globals)() = ScheduleUnregisterGlobals;
// ASan SEH handling.
// We need to set the ASan-specific SEH handler at the end of CRT initialization
// of each module (see also asan_win.cpp).
extern "C" {
__declspec(dllimport) int __asan_set_seh_filter();
static int SetSEHFilter() { return __asan_set_seh_filter(); }
// Unfortunately, putting a pointer to __asan_set_seh_filter into
// __asan_intercept_seh gets optimized out, so we have to use an extra function.
__declspec(allocate(".CRT$XCAB")) int (*__asan_seh_interceptor)() =