libgcc/config/nds32/initfini.c

   1 /* .init/.fini section handling + C++ global constructor/destructor
   2    handling of Andes NDS32 cpu for GNU compiler.
   3    This file is based on crtstuff.c, sol2-crti.asm, sol2-crtn.asm.
   4    Copyright (C) 2012-2024 Free Software Foundation, Inc.
   5    Contributed by Andes Technology Corporation.
   6
   7    This file is part of GCC.
   8
   9    GCC is free software; you can redistribute it and/or modify it
  10    under the terms of the GNU General Public License as published
  11    by the Free Software Foundation; either version 3, or (at your
  12    option) any later version.
  13
  14    GCC is distributed in the hope that it will be useful, but WITHOUT
  15    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  16    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  17    License for more details.
  18
  19    Under Section 7 of GPL version 3, you are granted additional
  20    permissions described in the GCC Runtime Library Exception, version
  21    3.1, as published by the Free Software Foundation.
  22
  23    You should have received a copy of the GNU General Public License and
  24    a copy of the GCC Runtime Library Exception along with this program;
  25    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  26    <http://www.gnu.org/licenses/>.  */
  27
  28 #include <stddef.h>
  29 /* Need header file for `struct object' type.  */
  30 #include "../libgcc/unwind-dw2-fde.h"
  31
  32 /*  Declare a pointer to void function type.  */
  33 typedef void (*func_ptr) (void);
  34
  35 #ifdef CRT_BEGIN
  36
  37 /* NOTE:  In order to be able to support SVR4 shared libraries, we arrange
  38    to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__,
  39    __DTOR_END__ } per root executable and also one set of these symbols
  40    per shared library.  So in any given whole process image, we may have
  41    multiple definitions of each of these symbols.  In order to prevent
  42    these definitions from conflicting with one another, and in order to
  43    ensure that the proper lists are used for the initialization/finalization
  44    of each individual shared library (respectively), we give these symbols
  45    only internal (i.e. `static') linkage, and we also make it a point to
  46    refer to only the __CTOR_END__ symbol in crtfini.o and the __DTOR_LIST__
  47    symbol in crtinit.o, where they are defined.  */
  48
  49 static func_ptr __CTOR_LIST__[1] __attribute__ ((section (".ctors"), used))
  50      = { (func_ptr) 0 };
  51
  52 static func_ptr __DTOR_LIST__[1] __attribute__ ((section (".dtors"), used))
  53      = { (func_ptr) 0 };
  54
  55
  56 #ifdef SUPPORT_UNWINDING_DWARF2
  57 /* Preparation of exception handling with dwar2 mechanism registration.  */
  58
  59 asm ("\n\
  60         .section .eh_frame,\"aw\",@progbits\n\
  61         .global __EH_FRAME_BEGIN__\n\
  62         .type   __EH_FRAME_BEGIN__, @object\n\
  63         .align 2\n\
  64 __EH_FRAME_BEGIN__:\n\
  65         ! Beginning location of eh_frame section\n\
  66         .previous\n\
  67 ");
  68
  69 extern func_ptr __EH_FRAME_BEGIN__[];
  70
  71
  72 /* Note that the following two functions are going to be chained into
  73    constructor and destructor list, repectively.  So these two declarations
  74    must be placed after __CTOR_LIST__ and __DTOR_LIST.  */
  75 extern void __nds32_register_eh(void) __attribute__((constructor, used));
  76 extern void __nds32_deregister_eh(void) __attribute__((destructor, used));
  77
  78 /* Register the exception handling table as the first constructor.  */
  79 void
  80 __nds32_register_eh (void)
  81 {
  82   static struct object object;
  83   if (__register_frame_info)
  84     __register_frame_info (__EH_FRAME_BEGIN__, &object);
  85 }
  86
  87 /* Unregister the exception handling table as a deconstructor.  */
  88 void
  89 __nds32_deregister_eh (void)
  90 {
  91   static int completed = 0;
  92
  93   if (completed)
  94     return;
  95
  96   if (__deregister_frame_info)
  97     __deregister_frame_info (__EH_FRAME_BEGIN__);
  98
  99   completed = 1;
 100 }
 101 #endif
 102
 103 /* Run all the global destructors on exit from the program.  */
 104
 105 /* Some systems place the number of pointers in the first word of the
 106    table.  On SVR4 however, that word is -1.  In all cases, the table is
 107    null-terminated.  On SVR4, we start from the beginning of the list and
 108    invoke each per-compilation-unit destructor routine in order
 109    until we find that null.
 110
 111    Note that this function MUST be static.  There will be one of these
 112    functions in each root executable and one in each shared library, but
 113    although they all have the same code, each one is unique in that it
 114    refers to one particular associated `__DTOR_LIST__' which belongs to the
 115    same particular root executable or shared library file.  */
 116
 117 static void __do_global_dtors (void)
 118 asm ("__do_global_dtors") __attribute__ ((section (".text"), used));
 119
 120 static void
 121 __do_global_dtors (void)
 122 {
 123   func_ptr *p;
 124   for (p = __DTOR_LIST__ + 1; *p; p++)
 125     (*p) ();
 126 }
 127
 128 /* .init section start.
 129    This must appear at the start of the .init section.  */
 130
 131 asm ("\n\
 132         .section .init\n\
 133         .global _init\n\
 134         .type   _init, @function\n\
 135 _init:\n\
 136         ! 1. store $fp\n\
 137         ! 2. adjust $fp by $sp\n\
 138         ! 3. adjust $sp\n\
 139 ");
 140
 141 /* .fini section start.
 142    This must appear at the start of the .fini section.  */
 143
 144 asm ("\n\
 145         .section .fini\n\
 146         .global _fini\n\
 147         .type   _fini, @function\n\
 148 _fini:\n\
 149         ! 1. store $fp\n\
 150         ! 2. adjust $fp by $sp\n\
 151         ! 3. adjust $sp\n\
 152         ! 4. call __do_global_dtors\n\
 153         j       __do_global_dtors\n\
 154 ");
 155
 156 #endif /* CRT_BEGIN */
 157
 158 #ifdef CRT_END
 159
 160 /* Define __dso_handle which would be needed for C++ library.
 161    Since our elf-toolchain only builds programs with static link,
 162    we can directly define 'void *__dso_handle = 0'.  */
 163 void *__dso_handle = 0;
 164
 165 /* Put a word containing zero at the end of each of our two lists of function
 166    addresses.  Note that the words defined here go into the .ctors and .dtors
 167    sections of the crtend.o file, and since that file is always linked in
 168    last, these words naturally end up at the very ends of the two lists
 169    contained in these two sections.  */
 170
 171 static func_ptr __CTOR_END__[1] __attribute__ ((section (".ctors"), used))
 172      = { (func_ptr) 0 };
 173
 174 static func_ptr __DTOR_END__[1] __attribute__ ((section (".dtors"), used))
 175      = { (func_ptr) 0 };
 176
 177 #ifdef SUPPORT_UNWINDING_DWARF2
 178 /* ZERO terminator in .eh_frame section.  */
 179 asm ("\n\
 180         .section .eh_frame,\"aw\",@progbits\n\
 181         .global __EH_FRAME_END__\n\
 182         .type   __EH_FRAME_END__, @object\n\
 183         .align 2\n\
 184 __EH_FRAME_END__:\n\
 185         ! End location of eh_frame section with ZERO terminator\n\
 186         .word 0\n\
 187         .previous\n\
 188 ");
 189 #endif
 190
 191 /* Run all global constructors for the program.
 192    Note that they are run in reverse order.  */
 193
 194 static void __do_global_ctors (void)
 195 asm ("__do_global_ctors") __attribute__ ((section (".text"), used));
 196
 197 static void
 198 __do_global_ctors (void)
 199 {
 200   func_ptr *p;
 201   for (p = __CTOR_END__ - 1; *p; p--)
 202     (*p) ();
 203 }
 204
 205 /* .init section end.
 206    This must live at the end of the .init section.  */
 207
 208 asm ("\n\
 209         .section .init\n\
 210         ! 1. call __do_global_ctors\n\
 211         ! 2. adjust back $sp\n\
 212         ! 3. restore $fp\n\
 213         j       __do_global_ctors\n\
 214 ");
 215
 216 /* .fini section end.
 217    This must live at the end of the .fini section.  */
 218
 219 asm ("\n\
 220         .section .fini\n\
 221         ! 1. adjust back $sp\n\
 222         ! 2. restore $fp\n\
 223 ");
 224
 225 #endif /* CRT_END */