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 * $FreeBSD$ 26 */ 27 28 .text 29 .align 4 30 .globl .rtld_start 31 .type .rtld_start,@function 32.rtld_start: 33 .cfi_startproc 34 .cfi_undefined %rip 35 xorq %rbp,%rbp # Clear frame pointer for good form 36 subq $24,%rsp # A place to store exit procedure addr 37 .cfi_def_cfa_offset 32 38 movq %rdi,%r12 39 movq %rsp,%rsi # save address of exit proc 40 movq %rsp,%rdx # construct address of obj_main 41 addq $8,%rdx 42 call _rtld # Call rtld(sp); returns entry point 43 popq %rsi # Get exit procedure address 44 .cfi_def_cfa_offset 24 45 movq %r12,%rdi # *ap 46/* 47 * At this point, %rax contains the entry point of the main program, and 48 * %rdx contains a pointer to a termination function that should be 49 * registered with atexit(). (crt1.o registers it.) 50 */ 51.globl .rtld_goto_main 52.rtld_goto_main: # This symbol exists just to make debugging easier. 53 jmp *%rax # Enter main program 54 .cfi_endproc 55 56 57/* 58 * Binder entry point. Control is transferred to here by code in the PLT. 59 * On entry, there are two arguments on the stack. In ascending address 60 * order, they are (1) "obj", a pointer to the calling object's Obj_Entry, 61 * and (2) "reloff", the byte offset of the appropriate relocation entry 62 * in the PLT relocation table. 63 * 64 * We are careful to preserve all registers, even the caller-save 65 * registers. That is because this code may be invoked by low-level 66 * assembly-language code that is not ABI-compliant. 67 * 68 * Stack map: 69 * reloff 0x60 70 * obj 0x58 71 * spare 0x50 72 * rflags 0x48 73 * rax 0x40 74 * rdx 0x38 75 * rcx 0x30 76 * rsi 0x28 77 * rdi 0x20 78 * r8 0x18 79 * r9 0x10 80 * r10 0x8 81 * r11 0x0 82 */ 83 .align 4 84 .globl _rtld_bind_start 85 .type _rtld_bind_start,@function 86_rtld_bind_start: 87 .cfi_startproc 88 .cfi_adjust_cfa_offset 16 89 subq $8,%rsp 90 .cfi_adjust_cfa_offset 8 91 pushfq # Save rflags 92 .cfi_adjust_cfa_offset 8 93 pushq %rax # Save %rax 94 .cfi_adjust_cfa_offset 8 95 .cfi_offset %rax,-32 96 pushq %rdx # Save %rdx 97 .cfi_adjust_cfa_offset 8 98 .cfi_offset %rdx,-40 99 pushq %rcx # Save %rcx 100 .cfi_adjust_cfa_offset 8 101 .cfi_offset %rcx,-48 102 pushq %rsi # Save %rsi 103 .cfi_adjust_cfa_offset 8 104 .cfi_offset %rsi,-56 105 pushq %rdi # Save %rdi 106 .cfi_adjust_cfa_offset 8 107 .cfi_offset %rdi,-64 108 pushq %r8 # Save %r8 109 .cfi_adjust_cfa_offset 8 110 .cfi_offset %r8,-72 111 pushq %r9 # Save %r9 112 .cfi_adjust_cfa_offset 8 113 .cfi_offset %r9,-80 114 pushq %r10 # Save %r10 115 .cfi_adjust_cfa_offset 8 116 .cfi_offset %r10,-88 117 pushq %r11 # Save %r11 118 .cfi_adjust_cfa_offset 8 119 .cfi_offset %r11,-96 120 121 movq 0x58(%rsp),%rdi # Fetch obj argument 122 movq 0x60(%rsp),%rsi # Fetch reloff argument 123 leaq (%rsi,%rsi,2),%rsi # multiply by 3 124 leaq (,%rsi,8),%rsi # now 8, for 24 (sizeof Elf_Rela) 125 126 call _rtld_bind # Transfer control to the binder 127 /* Now %rax contains the entry point of the function being called. */ 128 129 movq %rax,0x60(%rsp) # Store target over reloff argument 130 popq %r11 # Restore %r11 131 .cfi_adjust_cfa_offset -8 132 .cfi_restore %r11 133 popq %r10 # Restore %r10 134 .cfi_adjust_cfa_offset -8 135 .cfi_restore %r10 136 popq %r9 # Restore %r9 137 .cfi_adjust_cfa_offset -8 138 .cfi_restore %r9 139 popq %r8 # Restore %r8 140 .cfi_adjust_cfa_offset -8 141 .cfi_restore %r8 142 popq %rdi # Restore %rdi 143 .cfi_adjust_cfa_offset -8 144 .cfi_restore %rdi 145 popq %rsi # Restore %rsi 146 .cfi_adjust_cfa_offset -8 147 .cfi_restore %rsi 148 popq %rcx # Restore %rcx 149 .cfi_adjust_cfa_offset -8 150 .cfi_restore %rcx 151 popq %rdx # Restore %rdx 152 .cfi_adjust_cfa_offset -8 153 .cfi_restore %rdx 154 popq %rax # Restore %rax 155 .cfi_adjust_cfa_offset -8 156 .cfi_restore %rax 157 popfq # Restore rflags 158 .cfi_adjust_cfa_offset -8 159 leaq 16(%rsp),%rsp # Discard spare, obj, do not change rflags 160 ret # "Return" to target address 161 .cfi_endproc 162 .size _rtld_bind_start, . - _rtld_bind_start 163 164 .align 4 165 .globl rtld_dynamic_addr 166 .type rtld_dynamic_addr,@function 167rtld_dynamic_addr: 168 .cfi_startproc 169 .weak _DYNAMIC 170 .hidden _DYNAMIC 171 lea _DYNAMIC(%rip),%rax 172 ret 173 .cfi_endproc 174 .size rtld_dynamic_addr, . - rtld_dynamic_addr 175 176 .section .note.GNU-stack,"",%progbits 177