llvm-project

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//===-- asan_win_dynamic_runtime_thunk.cpp --------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of AddressSanitizer, an address sanity checker.
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//
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// This file defines things that need to be present in the application modules
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// to interact with the ASan DLL runtime correctly and can't be implemented
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// using the default "import library" generated when linking the DLL RTL.
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//
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// This includes:
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//  - creating weak aliases to default implementation imported from asan dll.
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//  - forwarding the detect_stack_use_after_return runtime option
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//  - working around deficiencies of the MD runtime
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//  - installing a custom SEH handler
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//
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//===----------------------------------------------------------------------===//
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#ifdef SANITIZER_DYNAMIC_RUNTIME_THUNK
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#define SANITIZER_IMPORT_INTERFACE 1
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#include "sanitizer_common/sanitizer_win_defs.h"
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#define WIN32_LEAN_AND_MEAN
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#include <windows.h>
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// Define weak alias for all weak functions imported from asan dll.
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#define INTERFACE_FUNCTION(Name)
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#define INTERFACE_WEAK_FUNCTION(Name) WIN_WEAK_IMPORT_DEF(Name)
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#include "asan_interface.inc"
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// First, declare CRT sections we'll be using in this file
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#pragma section(".CRT$XIB", long, read)
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#pragma section(".CRT$XID", long, read)
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#pragma section(".CRT$XCAB", long, read)
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#pragma section(".CRT$XTW", long, read)
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#pragma section(".CRT$XTY", long, read)
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#pragma section(".CRT$XLAB", long, read)
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////////////////////////////////////////////////////////////////////////////////
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// Define a copy of __asan_option_detect_stack_use_after_return that should be
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// used when linking an MD runtime with a set of object files on Windows.
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//
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// The ASan MD runtime dllexports '__asan_option_detect_stack_use_after_return',
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// so normally we would just dllimport it.  Unfortunately, the dllimport
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// attribute adds __imp_ prefix to the symbol name of a variable.
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// Since in general we don't know if a given TU is going to be used
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// with a MT or MD runtime and we don't want to use ugly __imp_ names on Windows
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// just to work around this issue, let's clone the variable that is constant
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// after initialization anyways.
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extern "C" {
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__declspec(dllimport) int __asan_should_detect_stack_use_after_return();
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int __asan_option_detect_stack_use_after_return;
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__declspec(dllimport) void* __asan_get_shadow_memory_dynamic_address();
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void* __asan_shadow_memory_dynamic_address;
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}
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static int InitializeClonedVariables() {
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  __asan_option_detect_stack_use_after_return =
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    __asan_should_detect_stack_use_after_return();
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  __asan_shadow_memory_dynamic_address =
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    __asan_get_shadow_memory_dynamic_address();
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  return 0;
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}
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static void NTAPI asan_thread_init(void *mod, unsigned long reason,
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    void *reserved) {
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  if (reason == DLL_PROCESS_ATTACH) InitializeClonedVariables();
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}
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// Our cloned variables must be initialized before C/C++ constructors.  If TLS
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// is used, our .CRT$XLAB initializer will run first. If not, our .CRT$XIB
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// initializer is needed as a backup.
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__declspec(allocate(".CRT$XIB")) int (*__asan_initialize_cloned_variables)() =
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    InitializeClonedVariables;
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__declspec(allocate(".CRT$XLAB")) void (NTAPI *__asan_tls_init)(void *,
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    unsigned long, void *) = asan_thread_init;
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////////////////////////////////////////////////////////////////////////////////
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// For some reason, the MD CRT doesn't call the C/C++ terminators during on DLL
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// unload or on exit.  ASan relies on LLVM global_dtors to call
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// __asan_unregister_globals on these events, which unfortunately doesn't work
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// with the MD runtime, see PR22545 for the details.
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// To work around this, for each DLL we schedule a call to UnregisterGlobals
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// using atexit() that calls a small subset of C terminators
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// where LLVM global_dtors is placed.  Fingers crossed, no other C terminators
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// are there.
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extern "C" int __cdecl atexit(void (__cdecl *f)(void));
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extern "C" void __cdecl _initterm(void *a, void *b);
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namespace {
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__declspec(allocate(".CRT$XTW")) void* before_global_dtors = 0;
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__declspec(allocate(".CRT$XTY")) void* after_global_dtors = 0;
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void UnregisterGlobals() {
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  _initterm(&before_global_dtors, &after_global_dtors);
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}
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int ScheduleUnregisterGlobals() {
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  return atexit(UnregisterGlobals);
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}
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}  // namespace
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// We need to call 'atexit(UnregisterGlobals);' as early as possible, but after
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// atexit() is initialized (.CRT$XIC).  As this is executed before C++
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// initializers (think ctors for globals), UnregisterGlobals gets executed after
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// dtors for C++ globals.
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__declspec(allocate(".CRT$XID"))
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int (*__asan_schedule_unregister_globals)() = ScheduleUnregisterGlobals;
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////////////////////////////////////////////////////////////////////////////////
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// ASan SEH handling.
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// We need to set the ASan-specific SEH handler at the end of CRT initialization
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// of each module (see also asan_win.cpp).
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extern "C" {
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__declspec(dllimport) int __asan_set_seh_filter();
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static int SetSEHFilter() { return __asan_set_seh_filter(); }
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// Unfortunately, putting a pointer to __asan_set_seh_filter into
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// __asan_intercept_seh gets optimized out, so we have to use an extra function.
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__declspec(allocate(".CRT$XCAB")) int (*__asan_seh_interceptor)() =
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    SetSEHFilter;
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}
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WIN_FORCE_LINK(__asan_dso_reg_hook)
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#endif // SANITIZER_DYNAMIC_RUNTIME_THUNK
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