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| Rev | Author | Line No. | Line |
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| 2933 | svoboda | 1 | /* |
| 2 | * Copyright (c) 2008 Jiri Svoboda |
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| 3 | * All rights reserved. |
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| 4 | * |
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| 5 | * Redistribution and use in source and binary forms, with or without |
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| 6 | * modification, are permitted provided that the following conditions |
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| 7 | * are met: |
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| 8 | * |
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| 9 | * - Redistributions of source code must retain the above copyright |
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| 10 | * notice, this list of conditions and the following disclaimer. |
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| 11 | * - Redistributions in binary form must reproduce the above copyright |
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| 12 | * notice, this list of conditions and the following disclaimer in the |
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| 13 | * documentation and/or other materials provided with the distribution. |
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| 14 | * - The name of the author may not be used to endorse or promote products |
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| 15 | * derived from this software without specific prior written permission. |
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| 16 | * |
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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| 27 | */ |
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| 28 | |||
| 29 | /** @addtogroup rtld rtld |
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| 30 | * @brief |
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| 31 | * @{ |
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| 32 | */ |
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| 33 | /** |
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| 34 | * @file |
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| 35 | */ |
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| 36 | |||
| 37 | void _rtld_main(void); |
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| 38 | |||
| 39 | #define ELF32_R_SYM(i) ((i)>>8) |
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| 40 | #define ELF32_R_TYPE(i) ((unsigned char)(i)) |
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| 41 | |||
| 42 | typedef struct { |
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| 43 | int d_tag; |
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| 44 | union { |
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| 45 | unsigned d_val; |
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| 46 | unsigned *d_ptr; |
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| 47 | } d_un; |
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| 48 | } elf32_dyn; |
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| 49 | |||
| 50 | typedef struct { |
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| 51 | unsigned r_offset; |
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| 52 | unsigned r_info; |
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| 53 | } elf32_rel; |
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| 54 | |||
| 55 | typedef struct { |
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| 56 | unsigned st_name; |
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| 57 | unsigned st_value; |
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| 58 | unsigned st_size; |
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| 59 | unsigned char st_info; |
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| 60 | unsigned char st_other; |
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| 61 | unsigned short st_shndx; |
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| 62 | } elf32_sym; |
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| 63 | |||
| 64 | static void kputint(unsigned i) |
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| 65 | { |
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| 66 | unsigned dummy; |
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| 67 | asm volatile ( |
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| 68 | "movl $30, %%eax;" |
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| 69 | "int $0x30" |
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| 70 | : "=d" (dummy) /* output - %edx clobbered */ |
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| 71 | : "d" (i) /* input */ |
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| 72 | : "%eax","%ecx" /* all scratch registers clobbered */ |
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| 73 | ); |
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| 74 | } |
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| 75 | |||
| 76 | void __bootstrap(void) |
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| 77 | { |
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| 78 | unsigned bias; |
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| 79 | unsigned *got; |
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| 80 | elf32_dyn *dynamic; |
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| 81 | unsigned *dptr; |
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| 82 | unsigned dval; |
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| 83 | int i; |
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| 84 | |||
| 85 | unsigned rel_entries; |
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| 86 | unsigned r_offset; |
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| 87 | unsigned r_info; |
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| 88 | unsigned rel_type; |
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| 89 | unsigned sym_idx; |
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| 90 | unsigned sym_addr; |
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| 91 | |||
| 92 | elf32_sym *sym_table; |
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| 93 | elf32_rel *rel_table; |
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| 94 | |||
| 95 | asm volatile ( |
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| 96 | "movl $30, %eax;" |
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| 97 | "int $0x30" |
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| 98 | ); |
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| 99 | |||
| 100 | /* Copied from libc/arch/ia32/entry.s */ |
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| 101 | /*asm volatile ( |
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| 102 | "mov %ss, %ax;" |
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| 103 | "mov %ax, %ds;" |
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| 104 | "mov %ax, %es;" |
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| 105 | "mov %ax, %fs;" |
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| 106 | );*/ |
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| 107 | |||
| 108 | |||
| 109 | asm volatile ( |
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| 110 | /* Calculate the bias into %0 */ |
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| 111 | " call .L0;" |
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| 112 | ".L0: pop %0;" |
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| 113 | " subl $.L0, %0;" |
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| 114 | |||
| 115 | /* Calculate run-time address of _DYNAMIC into %1 */ |
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| 116 | " movl $_DYNAMIC, %1;" /* Again, at link time 0-based VMA gets in */ |
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| 117 | " addl %0, %1;" /* Add bias to compute run-time address */ |
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| 118 | |||
| 119 | : "=r" (bias), "=r" (dynamic) |
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| 120 | ); |
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| 121 | |||
| 122 | kputint(bias); |
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| 123 | kputint((unsigned)dynamic); |
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| 124 | |||
| 125 | /* parse DYNAMIC */ |
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| 126 | got = 0; |
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| 127 | sym_table = 0; |
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| 128 | rel_table = 0; |
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| 129 | rel_entries = 0; |
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| 130 | |||
| 131 | i = 0; |
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| 132 | while (dynamic[i].d_tag != 0) { |
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| 133 | dptr = (unsigned *)(dynamic[i].d_un.d_val + bias); |
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| 134 | dval = dynamic[i].d_un.d_val; |
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| 135 | |||
| 136 | switch (dynamic[i].d_tag) { |
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| 137 | case 3 /* DT_PLTGOT */: |
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| 138 | /* GOT address */ |
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| 139 | got = dptr; break; |
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| 140 | case 6 /* DT_SYMTAB */ : sym_table = dptr; break; |
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| 141 | case 17 /* DT_REL */ : rel_table = dptr; break; |
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| 142 | case 18 /* DT_RELSZ */ : rel_entries = dval / 8; break; |
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| 143 | default: break; |
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| 144 | } |
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| 145 | |||
| 146 | ++i; |
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| 147 | } |
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| 148 | |||
| 149 | kputint(1); |
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| 150 | kputint((unsigned)sym_table); |
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| 151 | kputint((unsigned)rel_table); |
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| 152 | kputint((unsigned)rel_entries); |
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| 153 | |||
| 154 | /* Now relocate all our dynsyms */ |
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| 155 | kputint(-1); |
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| 156 | |||
| 157 | for (i=0; i<rel_entries; i++) { |
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| 158 | kputint(i); |
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| 159 | r_offset = rel_table[i].r_offset; |
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| 160 | r_info = rel_table[i].r_info; |
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| 161 | |||
| 162 | rel_type = ELF32_R_TYPE(r_info); |
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| 163 | |||
| 164 | kputint(rel_type); |
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| 165 | kputint(r_offset); |
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| 166 | |||
| 167 | if (rel_type == 7 /* R_386_JUMP_SLOT */) { |
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| 168 | kputint(16); |
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| 169 | sym_idx = ELF32_R_SYM(r_info); |
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| 170 | |||
| 171 | sym_addr = sym_table[sym_idx].st_value + bias; |
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| 172 | kputint(sym_idx); |
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| 173 | kputint(sym_addr); |
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| 174 | |||
| 175 | *(unsigned *)(r_offset+bias) = sym_addr; |
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| 176 | } |
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| 177 | } |
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| 178 | |||
| 179 | kputint(-1); |
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| 180 | |||
| 181 | kputint(32); |
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| 182 | |||
| 183 | _rtld_main(); |
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| 184 | |||
| 185 | asm ( |
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| 186 | "movl $250, %%eax;" |
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| 187 | "int $0x30" |
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| 188 | : /* output */ |
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| 189 | : /* input */ |
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| 190 | : "%eax","%ecx","%edx" /* all scratch registers clobbered */ |
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| 191 | ); |
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| 192 | } |
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| 193 | |||
| 194 | /** @} |
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| 195 | */ |