1/*- 2 * Copyright 1996-1998 John D. Polstra. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 .text 27 .align 4 28 .globl .rtld_start 29 .type .rtld_start,@function 30.rtld_start: 31 .cfi_startproc 32 .cfi_undefined %rip 33 xorq %rbp,%rbp # Clear frame pointer for good form 34 subq $24,%rsp # A place to store exit procedure addr 35 .cfi_def_cfa_offset 32 36 movq %rdi,%r12 37 movq %rsp,%rsi # save address of exit proc 38 movq %rsp,%rdx # construct address of obj_main 39 addq $8,%rdx 40 call _rtld # Call rtld(sp); returns entry point 41 popq %rsi # Get exit procedure address 42 .cfi_def_cfa_offset 24 43 movq %r12,%rdi # *ap 44/* 45 * At this point, %rax contains the entry point of the main program, and 46 * %rdx contains a pointer to a termination function that should be 47 * registered with atexit(). (crt1.o registers it.) 48 */ 49.globl .rtld_goto_main 50.rtld_goto_main: # This symbol exists just to make debugging easier. 51 jmp *%rax # Enter main program 52 .cfi_endproc 53 54 55/* 56 * Binder entry point. Control is transferred to here by code in the PLT. 57 * On entry, there are two arguments on the stack. In ascending address 58 * order, they are (1) "obj", a pointer to the calling object's Obj_Entry, 59 * and (2) "reloff", the byte offset of the appropriate relocation entry 60 * in the PLT relocation table. 61 * 62 * We are careful to preserve all registers, even the caller-save 63 * registers. That is because this code may be invoked by low-level 64 * assembly-language code that is not ABI-compliant. 65 * 66 * Stack map: 67 * reloff 0x60 68 * obj 0x58 69 * spare 0x50 70 * rflags 0x48 71 * rax 0x40 72 * rdx 0x38 73 * rcx 0x30 74 * rsi 0x28 75 * rdi 0x20 76 * r8 0x18 77 * r9 0x10 78 * r10 0x8 79 * r11 0x0 80 */ 81 .align 4 82 .globl _rtld_bind_start 83 .type _rtld_bind_start,@function 84_rtld_bind_start: 85 .cfi_startproc 86 .cfi_adjust_cfa_offset 16 87 subq $8,%rsp 88 .cfi_adjust_cfa_offset 8 89 pushfq # Save rflags 90 .cfi_adjust_cfa_offset 8 91 pushq %rax # Save %rax 92 .cfi_adjust_cfa_offset 8 93 .cfi_offset %rax,-32 94 pushq %rdx # Save %rdx 95 .cfi_adjust_cfa_offset 8 96 .cfi_offset %rdx,-40 97 pushq %rcx # Save %rcx 98 .cfi_adjust_cfa_offset 8 99 .cfi_offset %rcx,-48 100 pushq %rsi # Save %rsi 101 .cfi_adjust_cfa_offset 8 102 .cfi_offset %rsi,-56 103 pushq %rdi # Save %rdi 104 .cfi_adjust_cfa_offset 8 105 .cfi_offset %rdi,-64 106 pushq %r8 # Save %r8 107 .cfi_adjust_cfa_offset 8 108 .cfi_offset %r8,-72 109 pushq %r9 # Save %r9 110 .cfi_adjust_cfa_offset 8 111 .cfi_offset %r9,-80 112 pushq %r10 # Save %r10 113 .cfi_adjust_cfa_offset 8 114 .cfi_offset %r10,-88 115 pushq %r11 # Save %r11 116 .cfi_adjust_cfa_offset 8 117 .cfi_offset %r11,-96 118 119 movq 0x58(%rsp),%rdi # Fetch obj argument 120 movq 0x60(%rsp),%rsi # Fetch reloff argument 121 leaq (%rsi,%rsi,2),%rsi # multiply by 3 122 leaq (,%rsi,8),%rsi # now 8, for 24 (sizeof Elf_Rela) 123 124 call _rtld_bind # Transfer control to the binder 125 /* Now %rax contains the entry point of the function being called. */ 126 127 movq %rax,0x60(%rsp) # Store target over reloff argument 128 popq %r11 # Restore %r11 129 .cfi_adjust_cfa_offset -8 130 .cfi_restore %r11 131 popq %r10 # Restore %r10 132 .cfi_adjust_cfa_offset -8 133 .cfi_restore %r10 134 popq %r9 # Restore %r9 135 .cfi_adjust_cfa_offset -8 136 .cfi_restore %r9 137 popq %r8 # Restore %r8 138 .cfi_adjust_cfa_offset -8 139 .cfi_restore %r8 140 popq %rdi # Restore %rdi 141 .cfi_adjust_cfa_offset -8 142 .cfi_restore %rdi 143 popq %rsi # Restore %rsi 144 .cfi_adjust_cfa_offset -8 145 .cfi_restore %rsi 146 popq %rcx # Restore %rcx 147 .cfi_adjust_cfa_offset -8 148 .cfi_restore %rcx 149 popq %rdx # Restore %rdx 150 .cfi_adjust_cfa_offset -8 151 .cfi_restore %rdx 152 popq %rax # Restore %rax 153 .cfi_adjust_cfa_offset -8 154 .cfi_restore %rax 155 popfq # Restore rflags 156 .cfi_adjust_cfa_offset -8 157 leaq 16(%rsp),%rsp # Discard spare, obj, do not change rflags 158 ret # "Return" to target address 159 .cfi_endproc 160 .size _rtld_bind_start, . - _rtld_bind_start 161 162 .align 4 163 .globl rtld_dynamic_addr 164 .type rtld_dynamic_addr,@function 165rtld_dynamic_addr: 166 .cfi_startproc 167 .weak _DYNAMIC 168 .hidden _DYNAMIC 169 lea _DYNAMIC(%rip),%rax 170 ret 171 .cfi_endproc 172 .size rtld_dynamic_addr, . - rtld_dynamic_addr 173 174 .section .note.GNU-stack,"",%progbits 175