libgcc/config/vxcrtstuff.c

   1 /* This file is part of GCC.
   2
   3 GCC is free software; you can redistribute it and/or modify it under
   4 the terms of the GNU General Public License as published by the Free
   5 Software Foundation; either version 3, or (at your option) any later
   6 version.
   7
   8 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
   9 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11 for more details.
  12
  13 Under Section 7 of GPL version 3, you are granted additional
  14 permissions described in the GCC Runtime Library Exception, version
  15 3.1, as published by the Free Software Foundation.
  16
  17 You should have received a copy of the GNU General Public License and
  18 a copy of the GCC Runtime Library Exception along with this program;
  19 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 /* The essential point of the crtbegin/crtend files on VxWorks is to handle
  23    the eh frames registration thanks to dedicated constructors and
  24    destructors.  What needs to be done depends on the VxWorks version and the
  25    kind of module (rtp, dkm, ...) one is building.  */
  26
  27 #define IN_LIBGCC2
  28
  29 /* FIXME: Including auto-host is incorrect here (target library implementation
  30    file), but we still need it for DEFAULT_USE_CXA_ATEXIT and most importantly
  31    USE_INITFINI_ARRAY, guarded by HAVE_INITFINI_ARRAY_SUPPORT, not yet handled
  32    by auto-target.h.  Proceed as crtstuff.c, with the inclusion followed by a
  33    few #undefs preventing build failures in configurations setup for Windows
  34    hosts, including canadian builds.  #define USED_FOR_TARGET would circumvent
  35    this but would unfortunately also inhibit some of the definitions we
  36    need.  */
  37 #include "auto-host.h"
  38 #undef caddr_t
  39 #undef pid_t
  40 #undef rlim_t
  41 #undef ssize_t
  42 #undef vfork
  43
  44 #include "tconfig.h"
  45 #include "tsystem.h"
  46 #include "coretypes.h"
  47 #include "tm.h"
  48 #include "libgcc_tm.h"
  49 #include "unwind-dw2-fde.h"
  50
  51 /* If we are entitled/requested to use init/fini arrays, we'll rely on that.
  52    Otherwise, we may rely on ctors/dtors sections for RTPs or expect munch to
  53    be involved for kernel modules.  */
  54
  55 #if !defined(USE_INITFINI_ARRAY) && defined(__RTP__)
  56 #define USE_CDTORS_SECTIONS
  57 #endif
  58
  59 #if DWARF2_UNWIND_INFO && !defined(__USING_SJLJ_EXCEPTIONS__)
  60 #define USE_EH_FRAME_REGISTRY
  61 #endif
  62
  63 /*  ------------------------------ crtbegin -------------------------------  */
  64
  65 #ifdef CRT_BEGIN
  66
  67 /* Provide __dso_handle in RTP objects, which might be included in contexts
  68    involving shared objects.  This mimics the crtstuff.c behavior:  dso_handle
  69    should be NULL for the main program (in vx_crtbegin.o) and a unique value
  70    for the shared libraries (in vx_crtbeginS.o).  */
  71
  72 #if DEFAULT_USE_CXA_ATEXIT && defined(__RTP__)
  73 extern void *__dso_handle __attribute__ ((__visibility__ ("hidden")));
  74 #ifdef CRTSTUFFS_O
  75 void *__dso_handle = &__dso_handle;
  76 #else
  77 void *__dso_handle = 0;
  78 #endif
  79 #endif
  80
  81 /* Determine what names to use for the constructor/destructor functions.  */
  82
  83 #if defined(USE_CDTORS_SECTIONS) || defined(USE_INITFINI_ARRAY)
  84
  85 #define EH_CTOR_NAME _crtbe_register_frame
  86 #define EH_DTOR_NAME _ctrbe_deregister_frame
  87 #define EH_LINKAGE static
  88
  89 #else
  90
  91 /* No specific sections for constructors or destructors: we thus use a
  92    symbol naming convention so that the constructors are then recognized
  93    by munch or whatever tool is used for the final link phase.  Since the
  94    pointers to the constructor/destructor functions are not created in this
  95    translation unit, they must have external linkage.  */
  96 #define EH_CTOR_NAME _GLOBAL__I_00101_0__crtbe_register_frame
  97 #define EH_DTOR_NAME _GLOBAL__D_00101_1__crtbe_deregister_frame
  98 #define EH_LINKAGE
  99
 100 #endif
 101
 102 #ifdef USE_INITFINI_ARRAY
 103 /* .init_array and .fini_array is supported starting VxWorks 7.2 in all
 104    cases. The compiler is then configured to always support priorities in
 105    constructors, so we can rely on the constructor and destructor attributes
 106    to generate the proper sections.  */
 107 #define EH_CTOR_ATTRIBUTE __attribute__((constructor (101)))
 108 #define EH_DTOR_ATTRIBUTE __attribute__((destructor (101)))
 109
 110 /* Provide the init/fini array support functions for shared libraries,
 111    where we don't want to drag libc_internal contents blindly and which
 112    provides functions with a slightly different name anyway.  */
 113
 114 #if defined(CRTSTUFFS_O)
 115
 116 /* Run through the .init_array, .fini_array sections.  The linker script
 117    *must* provide __init_array_start, __init_array_end, __fini_array_start,
 118    __fini_array_end symbols.  */
 119
 120 typedef void (*initfini_ptr) (void);
 121 extern initfini_ptr __init_array_start[];
 122 extern initfini_ptr __init_array_end[];
 123 extern initfini_ptr __fini_array_start[];
 124 extern initfini_ptr __fini_array_end[];
 125
 126 /* Provide the actual code through static functions, which don't need
 127    to be exposed in the shared lib interface.  */
 128
 129 static void __exec_init_array(void)
 130 {
 131   initfini_ptr *fn;
 132   for (fn = __init_array_start; fn < __init_array_end; ++fn)
 133     (*fn)();
 134 }
 135
 136 static void __exec_fini_array(void)
 137 {
 138   initfini_ptr *fn;
 139   for (fn = __fini_array_end - 1; fn >= __fini_array_start; --fn)
 140     (*fn)();
 141 }
 142
 143 /* Reference the two above functions as the init / fini function.  */
 144
 145 void __attribute__ ((__section__  (".init"))) _init()
 146 {
 147   __exec_init_array();
 148 }
 149
 150 void __attribute__ ((__section__  (".fini"))) _fini()
 151 {
 152   __exec_fini_array();
 153 }
 154
 155 #endif /* __CRTSTUFFS_O__ */
 156
 157 #else /* !USE_INITFINI_ARRAY  */
 158
 159 /* Note: Even in case of .ctors/.dtors sections, we can't use the attribute
 160    (constructor (15)) here as gcc may have been configured with constructors
 161    priority disabled.  We will instead craft an explicit section name for this
 162    purpose.  */
 163 #define EH_CTOR_ATTRIBUTE
 164 #define EH_DTOR_ATTRIBUTE
 165
 166 #endif /* USE_INITFINI_ARRAY  */
 167
 168 #ifdef USE_EH_FRAME_REGISTRY
 169 /* Stick a label at the beginning of the frame unwind info so we can register
 170    and deregister it with the exception handling library code.  */
 171 static const char __EH_FRAME_BEGIN__[]
 172 __attribute__((section(__LIBGCC_EH_FRAME_SECTION_NAME__), aligned(4)))
 173   = { };
 174
 175 EH_LINKAGE EH_CTOR_ATTRIBUTE void EH_CTOR_NAME (void)
 176 {
 177   static struct object object;
 178   __register_frame_info (__EH_FRAME_BEGIN__, &object);
 179 }
 180
 181 EH_LINKAGE EH_DTOR_ATTRIBUTE void EH_DTOR_NAME (void)
 182 {
 183   __deregister_frame_info (__EH_FRAME_BEGIN__);
 184 }
 185 #endif /* USE_EH_FRAME_REGISTRY */
 186
 187 #ifdef USE_CDTORS_SECTIONS
 188 /* As explained above, we need to manually build the sections here as the
 189    compiler may not have support for constructors priority enabled.  */
 190 static void (* volatile eh_registration_ctors[])()
 191   __attribute__((section (".ctors.101")))
 192 = { &EH_CTOR_NAME };
 193 static void (* volatile eh_registration_dtors[])()
 194   __attribute__((section (".dtors.65434")))
 195 = { &EH_DTOR_NAME };
 196 #endif
 197
 198 /*  ------------------------------ crtend ---------------------------------  */
 199
 200 #elif defined (CRT_END) /* ! CRT_BEGIN */
 201
 202 #ifdef USE_EH_FRAME_REGISTRY
 203 /* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
 204    this would be the 'length' field in a real FDE.  */
 205
 206 static const char __FRAME_END__[]
 207      __attribute__ ((used, section(__LIBGCC_EH_FRAME_SECTION_NAME__),
 208                      aligned(4)))
 209   = { 0, 0, 0, 0 };
 210 #endif /* USE_EH_FRAME_REGISTRY */
 211
 212 #else /* ! CRT_BEGIN & ! CRT_END */
 213
 214 #error "One of CRT_BEGIN or CRT_END must be defined."
 215
 216 #endif