1/* crtbegin object for windows32 targets. 2 Copyright (C) 2007-2020 Free Software Foundation, Inc. 3 4 Contributed by Danny Smith <dannysmith@users.sourceforge.net> 5 6This file is part of GCC. 7 8GCC is free software; you can redistribute it and/or modify it under 9the terms of the GNU General Public License as published by the Free 10Software Foundation; either version 3, or (at your option) any later 11version. 12 13GCC is distributed in the hope that it will be useful, but WITHOUT ANY 14WARRANTY; without even the implied warranty of MERCHANTABILITY or 15FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 16for more details. 17 18Under Section 7 of GPL version 3, you are granted additional 19permissions described in the GCC Runtime Library Exception, version 203.1, as published by the Free Software Foundation. 21 22You should have received a copy of the GNU General Public License and 23a copy of the GCC Runtime Library Exception along with this program; 24see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 25<http://www.gnu.org/licenses/>. */ 26 27/* Target machine header files require this define. */ 28#define IN_LIBGCC2 29 30#include "auto-host.h" 31#include "tconfig.h" 32#include "tsystem.h" 33#include "coretypes.h" 34#include "tm.h" 35#include "libgcc_tm.h" 36#include "unwind-dw2-fde.h" 37 38#define WIN32_LEAN_AND_MEAN 39#include <windows.h> 40 41#ifndef LIBGCC_SONAME 42#define LIBGCC_SONAME "libgcc_s.dll" 43#endif 44 45#if DWARF2_UNWIND_INFO 46/* Make the declarations weak. This is critical for 47 _Jv_RegisterClasses because it lives in libgcj.a */ 48extern void __register_frame_info (__attribute__((unused)) const void *, 49 __attribute__((unused)) struct object *) 50 TARGET_ATTRIBUTE_WEAK; 51extern void *__deregister_frame_info (__attribute__((unused)) const void *) 52 TARGET_ATTRIBUTE_WEAK; 53 54/* Work around for current cygwin32 build problems (Bug gas/16858). 55 Compile weak default functions only for 64-bit systems, 56 when absolutely necessary. */ 57#ifdef __x86_64__ 58TARGET_ATTRIBUTE_WEAK void 59__register_frame_info (__attribute__((unused)) const void *p, 60 __attribute__((unused)) struct object *o) 61{ 62} 63 64TARGET_ATTRIBUTE_WEAK void * 65__deregister_frame_info (__attribute__((unused)) const void *p) 66{ 67 return (void*) 0; 68} 69#endif 70#endif /* DWARF2_UNWIND_INFO */ 71 72#if defined(HAVE_LD_RO_RW_SECTION_MIXING) 73# define EH_FRAME_SECTION_CONST const 74#else 75# define EH_FRAME_SECTION_CONST 76#endif 77 78/* Stick a label at the beginning of the frame unwind info so we can 79 register/deregister it with the exception handling library code. */ 80#if DWARF2_UNWIND_INFO 81static EH_FRAME_SECTION_CONST char __EH_FRAME_BEGIN__[] 82 __attribute__((used, section(__LIBGCC_EH_FRAME_SECTION_NAME__), aligned(4))) 83 = { }; 84 85static struct object obj; 86 87/* Handle of libgcc's DLL reference. */ 88HANDLE hmod_libgcc; 89static void * (*deregister_frame_fn) (const void *) = NULL; 90#endif 91 92#ifdef __CYGWIN__ 93/* Declare the __dso_handle variable. It should have a unique value 94 in every shared-object; in a main program its value is zero. The 95 object should in any case be protected. This means the instance 96 in one DSO or the main program is not used in another object. The 97 dynamic linker takes care of this. */ 98 99#ifdef CRTSTUFFS_O 100extern void *__ImageBase; 101void *__dso_handle = &__ImageBase; 102#else 103void *__dso_handle = 0; 104#endif 105 106#endif /* __CYGWIN__ */ 107 108 109/* Pull in references from libgcc.a(unwind-dw2-fde.o) in the 110 startfile. These are referenced by a ctor and dtor in crtend.o. */ 111extern void __gcc_register_frame (void); 112extern void __gcc_deregister_frame (void); 113 114void 115__gcc_register_frame (void) 116{ 117#if DWARF2_UNWIND_INFO 118/* Weak undefined symbols won't be pulled in from dlls; hence 119 we first test if the dll is already loaded and, if so, 120 get the symbol's address at run-time. If the dll is not loaded, 121 fallback to weak linkage to static archive. */ 122 123 void (*register_frame_fn) (const void *, struct object *); 124 HANDLE h = GetModuleHandle (LIBGCC_SONAME); 125 126 if (h) 127 { 128 /* Increasing the load-count of LIBGCC_SONAME DLL. */ 129 hmod_libgcc = LoadLibrary (LIBGCC_SONAME); 130 register_frame_fn = (void (*) (const void *, struct object *)) 131 GetProcAddress (h, "__register_frame_info"); 132 deregister_frame_fn = (void* (*) (const void *)) 133 GetProcAddress (h, "__deregister_frame_info"); 134 } 135 else 136 { 137 register_frame_fn = __register_frame_info; 138 deregister_frame_fn = __deregister_frame_info; 139 } 140 if (register_frame_fn) 141 register_frame_fn (__EH_FRAME_BEGIN__, &obj); 142#endif 143 144#if DEFAULT_USE_CXA_ATEXIT 145 /* If we use the __cxa_atexit method to register C++ dtors 146 at object construction, also use atexit to register eh frame 147 info cleanup. */ 148 atexit(__gcc_deregister_frame); 149#endif /* DEFAULT_USE_CXA_ATEXIT */ 150} 151 152void 153__gcc_deregister_frame (void) 154{ 155#if DWARF2_UNWIND_INFO 156 if (deregister_frame_fn) 157 deregister_frame_fn (__EH_FRAME_BEGIN__); 158 if (hmod_libgcc) 159 FreeLibrary (hmod_libgcc); 160#endif 161} 162