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 #include "auto-host.h"
  30 #include "tconfig.h"
  31 #include "tsystem.h"
  32 #include "coretypes.h"
  33 #include "tm.h"
  34 #include "libgcc_tm.h"
  35 #include "unwind-dw2-fde.h"
  36
  37 /* If we are entitled/requested to use init/fini arrays, we'll rely on that.
  38    Otherwise, we may rely on ctors/dtors sections for RTPs or expect munch to
  39    be involved for kernel modules.  */
  40
  41 #if !defined(USE_INITFINI_ARRAY) && defined(__RTP__)
  42 #define USE_CDTORS_SECTIONS
  43 #endif
  44
  45 /*  ------------------------------ crtbegin -------------------------------  */
  46
  47 #ifdef CRT_BEGIN
  48
  49 /* Stick a label at the beginning of the frame unwind info so we can register
  50    and deregister it with the exception handling library code.  */
  51 static const char __EH_FRAME_BEGIN__[]
  52 __attribute__((section(__LIBGCC_EH_FRAME_SECTION_NAME__), aligned(4)))
  53   = { };
  54
  55 /* Determine what names to use for the constructor/destructor functions.  */
  56
  57 #if defined(USE_CDTORS_SECTIONS) || defined(USE_INITFINI_ARRAY)
  58
  59 #define EH_CTOR_NAME _crtbe_register_frame
  60 #define EH_DTOR_NAME _ctrbe_deregister_frame
  61
  62 #else
  63
  64 /* No specific sections for constructors or destructors: we thus use a
  65    symbol naming convention so that the constructors are then recognized
  66    by munch or whatever tool is used for the final link phase.  */
  67 #define EH_CTOR_NAME _GLOBAL__I_00101_0__crtbe_register_frame
  68 #define EH_DTOR_NAME _GLOBAL__D_00101_1__crtbe_deregister_frame
  69
  70 #endif
  71
  72 #ifdef USE_INITFINI_ARRAY
  73 /* .init_array and .fini_array is supported starting VxWorks 7.2 in all
  74    cases. The compiler is then configured to always support priorities in
  75    constructors, so we can rely on the constructor and destructor attributes
  76    to generate the proper sections.  */
  77 #define EH_CTOR_ATTRIBUTE __attribute__((constructor (101)))
  78 #define EH_DTOR_ATTRIBUTE __attribute__((destructor (101)))
  79
  80 #else /* !USE_INITFINI_ARRAY  */
  81
  82 /* Note: Even in case of .ctors/.dtors sections, we can't use the attribute
  83    (constructor (15)) here as gcc may have been configured with constructors
  84    priority disabled.  We will instead craft an explicit section name for this
  85    purpose.  */
  86 #define EH_CTOR_ATTRIBUTE
  87 #define EH_DTOR_ATTRIBUTE
  88
  89 #endif /* USE_INITFINI_ARRAY  */
  90
  91 void EH_CTOR_NAME (void);
  92 void EH_DTOR_NAME (void);
  93
  94 EH_CTOR_ATTRIBUTE void EH_CTOR_NAME (void)
  95 {
  96   static struct object object;
  97   __register_frame_info (__EH_FRAME_BEGIN__, &object);
  98 }
  99
 100 EH_DTOR_ATTRIBUTE void EH_DTOR_NAME (void)
 101 {
 102   __deregister_frame_info (__EH_FRAME_BEGIN__);
 103 }
 104
 105 #ifdef USE_CDTORS_SECTIONS
 106 /* As explained above, we need to manually build the sections here as the
 107    compiler may not have support for constructors priority enabled.  */
 108 static void (* volatile eh_registration_ctors[])()
 109   __attribute__((section (".ctors.101")))
 110 = { &EH_CTOR_NAME };
 111 static void (* volatile eh_registration_dtors[])()
 112   __attribute__((section (".dtors.65434")))
 113 = { &EH_DTOR_NAME };
 114 #endif
 115
 116 /*  ------------------------------ crtend ---------------------------------  */
 117
 118 #elif defined (CRT_END) /* ! CRT_BEGIN */
 119
 120 /* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
 121    this would be the 'length' field in a real FDE.  */
 122
 123 static const char __FRAME_END__[]
 124      __attribute__ ((used, section(__LIBGCC_EH_FRAME_SECTION_NAME__),
 125                      aligned(4)))
 126   = { 0, 0, 0, 0 };
 127
 128 #else /* ! CRT_BEGIN & ! CRT_END */
 129
 130 #error "One of CRT_BEGIN or CRT_END must be defined."
 131
 132 #endif