l4/pkg/uclibc/lib/contrib/uclibc/ldso/ldso/arm/dl-startup.h

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Architecture specific code used by dl-startup.c
   4  * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
   5  *
   6  * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
   7  */
   8
   9 #include <features.h>
  10
  11 #if !defined(__thumb__)
  12 __asm__(
  13     "   .text\n"
  14     "   .globl  _start\n"
  15     "   .type   _start,%function\n"
  16         "_start:\n"
  17         "       @ at start time, all the args are on the stack\n"
  18         "       mov     r0, sp\n"
  19         "       bl      _dl_start\n"
  20         "       @ returns user entry point in r0\n"
  21         "       mov     r6, r0\n"
  22         "       @ we are PIC code, so get global offset table\n"
  23         "       ldr     sl, .L_GET_GOT\n"
  24         "       add     sl, pc, sl\n"
  25         ".L_GOT_GOT:\n"
  26         "       @ See if we were run as a command with the executable file\n"
  27         "       @ name as an extra leading argument.\n"
  28         "       ldr     r4, .L_SKIP_ARGS\n"
  29         "       ldr     r4, [sl, r4]\n"
  30         "       @ get the original arg count\n"
  31         "       ldr     r1, [sp]\n"
  32         "       @ subtract _dl_skip_args from it\n"
  33         "       sub     r1, r1, r4\n"
  34         "       @ adjust the stack pointer to skip them\n"
  35         "       add     sp, sp, r4, lsl #2\n"
  36         "       @ get the argv address\n"
  37         "       add     r2, sp, #4\n"
  38         "       @ store the new argc in the new stack location\n"
  39         "       str     r1, [sp]\n"
  40         "       @ compute envp\n"
  41         "       add     r3, r2, r1, lsl #2\n"
  42         "       add     r3, r3, #4\n"
  43         "\n\n"
  44         "       @ load the finalizer function\n"
  45         "       ldr     r0, .L_FINI_PROC\n"
  46         "       ldr     r0, [sl, r0]\n"
  47         "       @ jump to the user_s entry point\n"
  48 #if defined(__USE_BX__)
  49         "       bx      r6\n"
  50 #else
  51         "       mov     pc, r6\n"
  52 #endif
  53         ".L_GET_GOT:\n"
  54         "       .word   _GLOBAL_OFFSET_TABLE_ - .L_GOT_GOT - 4\n"
  55         ".L_SKIP_ARGS:\n"
  56         "       .word   _dl_skip_args(GOTOFF)\n"
  57         ".L_FINI_PROC:\n"
  58         "       .word   _dl_fini(GOT)\n"
  59         "\n\n"
  60     "   .size   _start,.-_start\n"
  61         ".previous\n"
  62 );
  63 #else
  64 __asm__(
  65     "   .text\n"
  66     "   .arm\n"
  67     "   .globl  _start\n"
  68     "   .type   _start,%function\n"
  69         "_start:\n"
  70         "       @ dumb: can't persuade the linker to make the start address\n"
  71         "       @ odd, so use an arm function and change to thumb (_dl_start\n"
  72         "       @ is thumb)\n"
  73         "       adr     r0, __dl_thumb_start+1\n"
  74         "       bx      r0\n"
  75         "\n\n"
  76     "   .thumb\n"
  77     "   .globl  __dl_thumb_start\n"
  78     "   .thumb_func\n"
  79     "   .type   __dl_thumb_start,%function\n"
  80         "__dl_thumb_start:\n"
  81         "       @ at start time, all the args are on the stack\n"
  82         "       mov     r0, sp\n"
  83         "       bl      _dl_start\n"
  84         "       @ returns user entry point in r0\n"
  85         "       mov     r6, r0\n"
  86         "       @ we are PIC code, so get global offset table\n"
  87         "       ldr     r7, .L_GET_GOT\n"
  88         ".L_GOT_GOT:\n"
  89         "       add     r7, pc\n"
  90         "       @ See if we were run as a command with the executable file\n"
  91         "       @ name as an extra leading argument.\n"
  92         "       ldr     r4, .L_SKIP_ARGS\n"
  93         "       ldr     r4, [r7, r4]\n"
  94         "       @ get the original arg count\n"
  95         "       ldr     r1, [sp]\n"
  96         "       @ subtract _dl_skip_args from it\n"
  97         "       sub     r1, r1, r4\n"
  98         "       @ adjust the stack pointer to skip them\n"
  99         "       lsl     r4, r4, #2\n"
 100         "       add     sp, r4\n"
 101         "       @ get the argv address\n"
 102         "       add     r2, sp, #4\n"
 103         "       @ store the new argc in the new stack location\n"
 104         "       str     r1, [sp]\n"
 105         "       @ compute envp\n"
 106         "       lsl     r3, r1, #2\n"
 107         "       add     r3, r3, r2\n"
 108         "       add     r3, #4\n"
 109         "\n\n"
 110         "       @ load the finalizer function\n"
 111         "       ldr     r0, .L_FINI_PROC\n"
 112         "       ldr     r0, [r7, r0]\n"
 113         "       @ jump to the user_s entry point\n"
 114 #if defined(__USE_BX__)
 115         "       bx      r6\n"
 116 #else
 117         "       mov     pc, r6\n"
 118 #endif
 119         "\n\n"
 120         ".L_GET_GOT:\n"
 121         "       .word   _GLOBAL_OFFSET_TABLE_ - .L_GOT_GOT - 4\n"
 122         ".L_SKIP_ARGS:\n"
 123         "       .word   _dl_skip_args(GOTOFF)\n"
 124         ".L_FINI_PROC:\n"
 125         "       .word   _dl_fini(GOT)\n"
 126         "\n\n"
 127     "   .size   _start,.-_start\n"
 128         ".previous\n"
 129 );
 130 #endif
 131
 132
 133 /* Get a pointer to the argv array.  On many platforms this can be just
 134  * the address of the first argument, on other platforms we need to
 135  * do something a little more subtle here.  */
 136 #define GET_ARGV(ARGVP, ARGS) ARGVP = (((unsigned long*)ARGS)+1)
 137
 138 /* Handle relocation of the symbols in the dynamic loader. */
 139 static __always_inline
 140 void PERFORM_BOOTSTRAP_RELOC(ELF_RELOC *rpnt, unsigned long *reloc_addr,
 141         unsigned long symbol_addr, unsigned long load_addr, Elf32_Sym *symtab)
 142 {
 143         switch (ELF32_R_TYPE(rpnt->r_info)) {
 144                 case R_ARM_NONE:
 145                         break;
 146                 case R_ARM_ABS32:
 147                         *reloc_addr += symbol_addr;
 148                         break;
 149                 case R_ARM_PC24:
 150                         {
 151                                 unsigned long addend;
 152                                 long newvalue, topbits;
 153
 154                                 addend = *reloc_addr & 0x00ffffff;
 155                                 if (addend & 0x00800000) addend |= 0xff000000;
 156
 157                                 newvalue = symbol_addr - (unsigned long)reloc_addr + (addend << 2);
 158                                 topbits = newvalue & 0xfe000000;
 159                                 if (topbits != 0xfe000000 && topbits != 0x00000000)
 160                                 {
 161 #if 0
 162                                         /* Don't bother with this during ldso initilization... */
 163                                         newvalue = fix_bad_pc24(reloc_addr, symbol_addr)
 164                                                 - (unsigned long)reloc_addr + (addend << 2);
 165                                         topbits = newvalue & 0xfe000000;
 166                                         if (unlikely(topbits != 0xfe000000 && topbits != 0x00000000))
 167                                         {
 168                                                 SEND_STDERR("R_ARM_PC24 relocation out of range\n");
 169                                                 _dl_exit(1);
 170                                         }
 171 #else
 172                                         SEND_STDERR("R_ARM_PC24 relocation out of range\n");
 173                                         _dl_exit(1);
 174 #endif
 175                                 }
 176                                 newvalue >>= 2;
 177                                 symbol_addr = (*reloc_addr & 0xff000000) | (newvalue & 0x00ffffff);
 178                                 *reloc_addr = symbol_addr;
 179                                 break;
 180                         }
 181                 case R_ARM_GLOB_DAT:
 182                 case R_ARM_JUMP_SLOT:
 183                         *reloc_addr = symbol_addr;
 184                         break;
 185                 case R_ARM_RELATIVE:
 186                         *reloc_addr += load_addr;
 187                         break;
 188                 case R_ARM_COPY:
 189                         break;
 190                 default:
 191                         SEND_STDERR("Unsupported relocation type\n");
 192                         _dl_exit(1);
 193         }
 194 }