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 %eip 33 xorl %ebp,%ebp # Clear frame pointer for good form 34 movl %esp,%esi # Save initial stack pointer 35 pushl %ebp 36 .cfi_def_cfa_offset 4 37 movl %esp,%ebp 38 .cfi_offset %ebp,-4 39 .cfi_def_cfa_register %ebp 40 andl $0xfffffff0,%esp # Align stack pointer 41 subl $16,%esp # A place to store exit procedure addr 42 movl %esp,%ebx # save address of exit proc 43 movl %esp,%ecx # construct address of obj_main 44 addl $4,%ecx 45 subl $4,%esp # Keep stack aligned 46 pushl %ecx # Pass address of obj_main 47 pushl %ebx # Pass address of exit proc 48 pushl %esi # Pass initial stack pointer to rtld 49 call _rtld # Call rtld(sp); returns entry point 50 addl $16,%esp # Remove arguments from stack 51 popl %edx # Get exit procedure address 52 movl %esi,%esp # Ignore obj_main 53/* 54 * At this point, %eax contains the entry point of the main program, and 55 * %edx contains a pointer to a termination function that should be 56 * registered with atexit(). (crt1.o registers it.) 57 */ 58.globl .rtld_goto_main 59.rtld_goto_main: # This symbol exists just to make debugging easier. 60 jmp *%eax # Enter main program 61 .cfi_endproc 62 63 64/* 65 * Binder entry point. Control is transferred to here by code in the PLT. 66 * On entry, there are two arguments on the stack. In ascending address 67 * order, they are (1) "obj", a pointer to the calling object's Obj_Entry, 68 * and (2) "reloff", the byte offset of the appropriate relocation entry 69 * in the PLT relocation table. 70 * 71 * We are careful to preserve all registers, even the caller-save 72 * registers. That is because this code may be invoked by low-level 73 * assembly-language code that is not ABI-compliant. 74 */ 75 .align 4 76 .globl _rtld_bind_start 77 .type _rtld_bind_start,@function 78_rtld_bind_start: 79 pushf # Save eflags 80 pushl %eax # Save %eax 81 pushl %edx # Save %edx 82 pushl %ecx # Save %ecx 83 pushl 20(%esp) # Copy reloff argument 84 pushl 20(%esp) # Copy obj argument 85 86 call _rtld_bind # Transfer control to the binder 87 /* Now %eax contains the entry point of the function being called. */ 88 89 addl $8,%esp # Discard binder arguments 90 movl %eax,20(%esp) # Store target over obj argument 91 popl %ecx # Restore %ecx 92 popl %edx # Restore %edx 93 popl %eax # Restore %eax 94 popf # Restore eflags 95 leal 4(%esp),%esp # Discard reloff, do not change eflags 96 ret # "Return" to target address 97 98 .section .note.GNU-stack,"",%progbits 99