ldso/ldso/bfin/dl-startup.h

   1      /* Copyright (C) 2003 Red Hat, Inc.
   2         Contributed by Alexandre Oliva <aoliva@redhat.com>
   3
   4 This file is part of uClibc.
   5
   6 uClibc is free software; you can redistribute it and/or modify it
   7 under the terms of the GNU Lesser General Public License as
   8 published by the Free Software Foundation; either version 2.1 of the
   9 License, or (at your option) any later version.
  10
  11 uClibc is distributed in the hope that it will be useful, but WITHOUT
  12 ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 Library General Public License for more details.
  15
  16 You should have received a copy of the GNU Lesser General Public
  17 License along with uClibc; see the file COPYING.LIB.  If not, see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 /* Any assembly language/system dependent hacks needed to setup
  21  * boot1.c so it will work as expected and cope with whatever platform
  22  * specific wierdness is needed for this architecture.
  23  */
  24
  25 /* At program start-up, p0 contains a pointer to a
  26    elf32_fdpic_loadmap that describes how the executable was loaded
  27    into memory.  p1 contains a pointer to the interpreter (our!)
  28    loadmap, if there is an interpreter, or 0 if we're being run as an
  29    executable.  p2 holds a pointer to the interpreter's dynamic
  30    section, if there is an interpreter, or to the executable's dynamic
  31    section, otherwise.  If the executable is not dynamic, gr18 is 0.
  32
  33    We rely on the fact that the linker adds a pointer to the
  34    _GLOBAL_OFFSET_TABLE_ as the last ROFIXUP entry, and that
  35    __self_reloc returns the relocated pointer to us, so that we can
  36    use this value to initialize the PIC register.  */
  37
  38 __asm__(
  39         "       .text\n"
  40         "       .global __start\n"
  41         "       .type   __start,@function\n"
  42         /* Build system expects a "_start" for the entry point;
  43            provide it as it's free to do so with aliases.  */
  44         "       .hidden __start\n"
  45         "       .set    _start, __start\n"
  46         "       .global _start\n"
  47         "       .hidden _start\n"
  48         "__start:\n"
  49         "       call    .Lcall\n"
  50         ".Lcall:\n"
  51         "       R4 = RETS;\n"
  52         "       SP += -32;\n"
  53         "       R5 = P0;\n"
  54         "       R6 = P1;\n"
  55         "       R7 = P2;\n"
  56         "       R0.L = .Lcall;\n"
  57         "       R0.H = .Lcall;\n"
  58         "       R1.L = __ROFIXUP_LIST__;\n"
  59         "       R1.H = __ROFIXUP_LIST__;\n"
  60         "       R2.L = __ROFIXUP_END__;\n"
  61         "       R2.H = __ROFIXUP_END__;\n"
  62         "       R1 = R1 - R0;\n"
  63         "       R1 = R1 + R4;\n"
  64         "       R2 = R2 - R0;\n"
  65         "       R2 = R2 + R4;\n"
  66         "       R0 = P1;\n"
  67         "       CC = R0 == 0;\n"
  68         "       IF CC R0 = P0;\n"
  69         "       CALL    ___self_reloc;\n"
  70         "       P3 = R0;\n"
  71         "       P5 = R0;\n"
  72         "       R1 = R5;\n"
  73         "       R2 = R6;\n"
  74         "       [SP + 12] = R7;\n"
  75         "       P0 = SP;\n"
  76         "       P0 += 24;\n"
  77         "       [SP + 16] = P0;\n"
  78         "       P0 += 8;\n"
  79         "       [SP + 20] = P0;\n"
  80         "       CALL    __dl_start;\n"
  81         "       /* Pass our FINI ptr() to the user in P1 */\n"
  82         "       R7 = [P5 + __dl_fini@FUNCDESC_GOT17M4];\n"
  83         "       P4 = [SP + 24];\n"
  84         "       P3 = [SP + 28];\n"
  85         "       P0 = R5;\n"
  86         "       SP += 32;\n"
  87         "       JUMP (P4);\n"
  88         "       .size   __start,.-__start\n"
  89 );
  90
  91 #undef DL_START
  92 #define DL_START(X)   \
  93 static void  __attribute__ ((used)) \
  94 _dl_start (Elf32_Addr dl_boot_got_pointer, \
  95            struct elf32_fdpic_loadmap *dl_boot_progmap, \
  96            struct elf32_fdpic_loadmap *dl_boot_ldsomap, \
  97            Elf32_Dyn *dl_boot_ldso_dyn_pointer, \
  98            struct funcdesc_value *dl_main_funcdesc, \
  99            X)
 100
 101 /*
 102  * Get a pointer to the argv array.  On many platforms this can be just
 103  * the address of the first argument, on other platforms we need to
 104  * do something a little more subtle here.
 105  */
 106 #define GET_ARGV(ARGVP, ARGS) ARGVP = (((unsigned long*) ARGS) + 1)
 107
 108 /*
 109  * Here is a macro to perform a relocation.  This is only used when
 110  * bootstrapping the dynamic loader.  RELP is the relocation that we
 111  * are performing, REL is the pointer to the address we are relocating.
 112  * SYMBOL is the symbol involved in the relocation, and LOAD is the
 113  * load address.
 114  */
 115 #define PERFORM_BOOTSTRAP_RELOC(RELP,REL,SYMBOL,LOAD,SYMTAB) \
 116         switch(ELF_R_TYPE((RELP)->r_info)){                             \
 117         case R_BFIN_BYTE4_DATA:                                                 \
 118           *(REL) += (SYMBOL);                                           \
 119           break;                                                        \
 120         case R_BFIN_FUNCDESC_VALUE:                                     \
 121           {                                                             \
 122             struct funcdesc_value fv = {                                \
 123               (void*)((SYMBOL) + *(REL)),                               \
 124               (LOAD).got_value                                          \
 125             };                                                          \
 126             *(struct funcdesc_value volatile *)(REL) = fv;              \
 127             break;                                                      \
 128           }                                                             \
 129         default:                                                        \
 130           _dl_exit(1);                                                  \
 131         }
 132
 133 /*
 134  * Transfer control to the user's application, once the dynamic loader
 135  * is done.  We return the address of the function's entry point to
 136  * _dl_boot, see boot1_arch.h.
 137  */
 138 #define START() do {                                                    \
 139   struct elf_resolve *exec_mod = _dl_loaded_modules;                    \
 140   dl_main_funcdesc->entry_point = _dl_elf_main;                         \
 141   while (exec_mod->libtype != elf_executable)                           \
 142     exec_mod = exec_mod->next;                                          \
 143   dl_main_funcdesc->got_value = exec_mod->loadaddr.got_value;           \
 144   return;                                                               \
 145 } while (0)