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 #include <bits/arm_bx.h>
  11
  12 #if !defined(__thumb__)
  13 __asm__(
  14     "   .text\n"
  15     "   .globl  _start\n"
  16     "   .type   _start,%function\n"
  17         "       .hidden _start\n"
  18         "_start:\n"
  19         "       @ at start time, all the args are on the stack\n"
  20         "       mov     r0, sp\n"
  21         "       bl      _dl_start\n"
  22         "       @ returns user entry point in r0\n"
  23         "       mov     r6, r0\n"
  24         "       @ we are PIC code, so get global offset table\n"
  25         "       ldr     sl, .L_GET_GOT\n"
  26         "       add     sl, pc, sl\n"
  27         ".L_GOT_GOT:\n"
  28         "       @ See if we were run as a command with the executable file\n"
  29         "       @ name as an extra leading argument.\n"
  30         "       ldr     r4, .L_SKIP_ARGS\n"
  31         "       ldr     r4, [sl, r4]\n"
  32         "       @ get the original arg count\n"
  33         "       ldr     r1, [sp]\n"
  34         "       @ subtract _dl_skip_args from it\n"
  35         "       sub     r1, r1, r4\n"
  36         "       @ adjust the stack pointer to skip them\n"
  37         "       add     sp, sp, r4, lsl #2\n"
  38         "       @ get the argv address\n"
  39         "       add     r2, sp, #4\n"
  40         "       @ store the new argc in the new stack location\n"
  41         "       str     r1, [sp]\n"
  42         "       @ compute envp\n"
  43         "       add     r3, r2, r1, lsl #2\n"
  44         "       add     r3, r3, #4\n"
  45         "\n\n"
  46         "       @ load the finalizer function\n"
  47         "       ldr     r0, .L_FINI_PROC\n"
  48         "       ldr     r0, [sl, r0]\n"
  49         "       @ jump to the user_s entry point\n"
  50 #if defined(__USE_BX__)
  51         "       bx      r6\n"
  52 #else
  53         "       mov     pc, r6\n"
  54 #endif
  55         ".L_GET_GOT:\n"
  56         "       .word   _GLOBAL_OFFSET_TABLE_ - .L_GOT_GOT - 4\n"
  57         ".L_SKIP_ARGS:\n"
  58         "       .word   _dl_skip_args(GOTOFF)\n"
  59         ".L_FINI_PROC:\n"
  60         "       .word   _dl_fini(GOT)\n"
  61         "\n\n"
  62     "   .size   _start,.-_start\n"
  63         ".previous\n"
  64 );
  65 #else
  66 __asm__(
  67     "   .text\n"
  68     "   .arm\n"
  69     "   .globl  _start\n"
  70     "   .type   _start,%function\n"
  71         "_start:\n"
  72         "       @ dumb: can't persuade the linker to make the start address\n"
  73         "       @ odd, so use an arm function and change to thumb (_dl_start\n"
  74         "       @ is thumb)\n"
  75         "       adr     r0, __dl_thumb_start+1\n"
  76         "       bx      r0\n"
  77         "\n\n"
  78     "   .thumb\n"
  79     "   .globl  __dl_thumb_start\n"
  80     "   .thumb_func\n"
  81     "   .type   __dl_thumb_start,%function\n"
  82         "__dl_thumb_start:\n"
  83         "       @ at start time, all the args are on the stack\n"
  84         "       mov     r0, sp\n"
  85         "       bl      _dl_start\n"
  86         "       @ returns user entry point in r0\n"
  87         "       mov     r6, r0\n"
  88         "       @ we are PIC code, so get global offset table\n"
  89         "       ldr     r7, .L_GET_GOT\n"
  90         ".L_GOT_GOT:\n"
  91         "       add     r7, pc\n"
  92         "       @ See if we were run as a command with the executable file\n"
  93         "       @ name as an extra leading argument.\n"
  94         "       ldr     r4, .L_SKIP_ARGS\n"
  95         "       ldr     r4, [r7, r4]\n"
  96         "       @ get the original arg count\n"
  97         "       ldr     r1, [sp]\n"
  98         "       @ subtract _dl_skip_args from it\n"
  99         "       sub     r1, r1, r4\n"
 100         "       @ adjust the stack pointer to skip them\n"
 101         "       lsl     r4, r4, #2\n"
 102         "       add     sp, r4\n"
 103         "       @ get the argv address\n"
 104         "       add     r2, sp, #4\n"
 105         "       @ store the new argc in the new stack location\n"
 106         "       str     r1, [sp]\n"
 107         "       @ compute envp\n"
 108         "       lsl     r3, r1, #2\n"
 109         "       add     r3, r3, r2\n"
 110         "       add     r3, #4\n"
 111         "\n\n"
 112         "       @ load the finalizer function\n"
 113         "       ldr     r0, .L_FINI_PROC\n"
 114         "       ldr     r0, [r7, r0]\n"
 115         "       @ jump to the user_s entry point\n"
 116 #if defined(__USE_BX__)
 117         "       bx      r6\n"
 118 #else
 119         "       mov     pc, r6\n"
 120 #endif
 121         "\n\n"
 122         ".L_GET_GOT:\n"
 123         "       .word   _GLOBAL_OFFSET_TABLE_ - .L_GOT_GOT - 4\n"
 124         ".L_SKIP_ARGS:\n"
 125         "       .word   _dl_skip_args(GOTOFF)\n"
 126         ".L_FINI_PROC:\n"
 127         "       .word   _dl_fini(GOT)\n"
 128         "\n\n"
 129     "   .size   _start,.-_start\n"
 130         ".previous\n"
 131 );
 132 #endif
 133
 134
 135 /* Get a pointer to the argv array.  On many platforms this can be just
 136  * the address of the first argument, on other platforms we need to
 137  * do something a little more subtle here.  */
 138 #define GET_ARGV(ARGVP, ARGS) ARGVP = (((unsigned long*)ARGS)+1)
 139
 140 /* Handle relocation of the symbols in the dynamic loader. */
 141 static __always_inline
 142 void PERFORM_BOOTSTRAP_RELOC(ELF_RELOC *rpnt, unsigned long *reloc_addr,
 143         unsigned long symbol_addr, unsigned long load_addr, Elf32_Sym *symtab)
 144 {
 145         switch (ELF_R_TYPE(rpnt->r_info)) {
 146                 case R_ARM_NONE:
 147                         break;
 148                 case R_ARM_ABS32:
 149                         *reloc_addr += symbol_addr;
 150                         break;
 151                 case R_ARM_PC24:
 152                         {
 153                                 unsigned long addend;
 154                                 long newvalue, topbits;
 155
 156                                 addend = *reloc_addr & 0x00ffffff;
 157                                 if (addend & 0x00800000) addend |= 0xff000000;
 158
 159                                 newvalue = symbol_addr - (unsigned long)reloc_addr + (addend << 2);
 160                                 topbits = newvalue & 0xfe000000;
 161                                 if (topbits != 0xfe000000 && topbits != 0x00000000)
 162                                 {
 163 #if 0
 164                                         /* Don't bother with this during ldso initilization... */
 165                                         newvalue = fix_bad_pc24(reloc_addr, symbol_addr)
 166                                                 - (unsigned long)reloc_addr + (addend << 2);
 167                                         topbits = newvalue & 0xfe000000;
 168                                         if (unlikely(topbits != 0xfe000000 && topbits != 0x00000000))
 169                                         {
 170                                                 SEND_STDERR("R_ARM_PC24 relocation out of range\n");
 171                                                 _dl_exit(1);
 172                                         }
 173 #else
 174                                         SEND_STDERR("R_ARM_PC24 relocation out of range\n");
 175                                         _dl_exit(1);
 176 #endif
 177                                 }
 178                                 newvalue >>= 2;
 179                                 symbol_addr = (*reloc_addr & 0xff000000) | (newvalue & 0x00ffffff);
 180                                 *reloc_addr = symbol_addr;
 181                                 break;
 182                         }
 183                 case R_ARM_GLOB_DAT:
 184                 case R_ARM_JUMP_SLOT:
 185                         *reloc_addr = symbol_addr;
 186                         break;
 187                 case R_ARM_RELATIVE:
 188                         *reloc_addr += load_addr;
 189                         break;
 190                 case R_ARM_COPY:
 191                         break;
 192                 default:
 193                         SEND_STDERR("Unsupported relocation type\n");
 194                         _dl_exit(1);
 195         }
 196 }