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/* 29 * Dynamic program start. argv pointer is in %rdi. 30 */ 31 .text 32 .align 4 33 .globl resident_start 34 .globl .rtld_start 35 .type .rtld_start,@function 36resident_start: 37.rtld_start: 38 xorq %rbp,%rbp # Clear frame pointer for good form 39 subq $24,%rsp # A place to store exit procedure addr 40 movq %rdi,%r12 41 movq %rsp,%rsi # save address of exit proc 42 movq %rsp,%rdx # construct address of obj_main 43 addq $8,%rdx 44 call _rtld@PLT # Call rtld(sp); returns entry point 45 popq %rsi # Get exit procedure address 46 movq %r12,%rdi # *ap 47/* 48 * At this point, %rax contains the entry point of the main program, and 49 * %rdx contains a pointer to a termination function that should be 50 * registered with atexit(). (crt1.o registers it.) 51 */ 52.globl .rtld_goto_main 53.rtld_goto_main: # This symbol exists just to make debugging easier. 54 jmp *%rax # Enter main program 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 subq $8,%rsp 88 pushfq # Save rflags 89 pushq %rax # Save %rax 90 pushq %rdx # Save %rdx 91 pushq %rcx # Save %rcx 92 pushq %rsi # Save %rsi 93 pushq %rdi # Save %rdi 94 pushq %r8 # Save %r8 95 pushq %r9 # Save %r9 96 pushq %r10 # Save %r10 97 pushq %r11 # Save %r11 98 subq $128,%rsp 99 movups %xmm0,0(%rsp) # Save xmm regs that might be 100 movups %xmm1,16(%rsp) # used for scratch. clang may 101 movups %xmm2,32(%rsp) # use them for fast structural copies. 102 movups %xmm3,48(%rsp) 103 movups %xmm4,64(%rsp) 104 movups %xmm5,80(%rsp) 105 movups %xmm6,96(%rsp) 106 movups %xmm7,112(%rsp) 107 108 movq 128+0x58(%rsp),%rdi # Fetch obj argument (arg 1) 109 movq 128+0x60(%rsp),%rsi # Fetch reloff argument (arg 2) 110 leaq 128+0x68(%rsp),%rdx # Fetch original stack pointer (arg 3) 111 leaq (%rsi,%rsi,2),%rsi # multiply by 3 112 leaq (,%rsi,8),%rsi # now 8, for 24 (sizeof Elf_Rela) 113 114 call _rtld_bind@PLT # Transfer control to the binder 115 /* Now %rax contains the entry point of the function being called. */ 116 117 movq %rax,128+0x60(%rsp) # Store target over reloff argument 118 119 movups 0(%rsp),%xmm0 120 movups 16(%rsp),%xmm1 121 movups 32(%rsp),%xmm2 122 movups 48(%rsp),%xmm3 123 movups 64(%rsp),%xmm4 124 movups 80(%rsp),%xmm5 125 movups 96(%rsp),%xmm6 126 movups 112(%rsp),%xmm7 127 leaq 128(%rsp),%rsp 128 129 popq %r11 # Restore %r11 130 popq %r10 # Restore %r10 131 popq %r9 # Restore %r9 132 popq %r8 # Restore %r8 133 popq %rdi # Restore %rdi 134 popq %rsi # Restore %rsi 135 popq %rcx # Restore %rcx 136 popq %rdx # Restore %rdx 137 popq %rax # Restore %rax 138 popfq # Restore rflags 139 leaq 16(%rsp),%rsp # Discard spare, obj, 140 # do not change rflags 141 ret # "Return" to target address 142 143 .section .note.GNU-stack,"",%progbits 144