2 * Copyright 1996-1998 John D. Polstra.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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.
31 .type .rtld_start,@function
33 xorq %rbp,%rbp # Clear frame pointer for good form
34 subq $24,%rsp # A place to store exit procedure addr
36 movq %rsp,%rsi # save address of exit proc
37 movq %rsp,%rdx # construct address of obj_main
39 call _rtld@PLT # Call rtld(sp); returns entry point
40 popq %rsi # Get exit procedure address
43 * At this point, %rax contains the entry point of the main program, and
44 * %rdx contains a pointer to a termination function that should be
45 * registered with atexit(). (crt1.o registers it.)
47 .globl .rtld_goto_main
48 .rtld_goto_main: # This symbol exists just to make debugging easier.
49 jmp *%rax # Enter main program
53 * Binder entry point. Control is transferred to here by code in the PLT.
54 * On entry, there are two arguments on the stack. In ascending address
55 * order, they are (1) "obj", a pointer to the calling object's Obj_Entry,
56 * and (2) "reloff", the byte offset of the appropriate relocation entry
57 * in the PLT relocation table.
59 * We are careful to preserve all registers, even the caller-save
60 * registers. That is because this code may be invoked by low-level
61 * assembly-language code that is not ABI-compliant.
79 .globl _rtld_bind_start
80 .type _rtld_bind_start,@function
83 .cfi_adjust_cfa_offset 16
85 .cfi_adjust_cfa_offset 8
87 .cfi_adjust_cfa_offset 8
88 pushq %rax # Save %rax
89 .cfi_adjust_cfa_offset 8
91 pushq %rdx # Save %rdx
92 .cfi_adjust_cfa_offset 8
94 pushq %rcx # Save %rcx
95 .cfi_adjust_cfa_offset 8
97 pushq %rsi # Save %rsi
98 .cfi_adjust_cfa_offset 8
100 pushq %rdi # Save %rdi
101 .cfi_adjust_cfa_offset 8
104 .cfi_adjust_cfa_offset 8
107 .cfi_adjust_cfa_offset 8
109 pushq %r10 # Save %r10
110 .cfi_adjust_cfa_offset 8
112 pushq %r11 # Save %r11
113 .cfi_adjust_cfa_offset 8
116 movq 0x58(%rsp),%rdi # Fetch obj argument
117 movq 0x60(%rsp),%rsi # Fetch reloff argument
118 leaq (%rsi,%rsi,2),%rsi # multiply by 3
119 leaq (,%rsi,8),%rsi # now 8, for 24 (sizeof Elf_Rela)
121 call _rtld_bind@PLT # Transfer control to the binder
122 /* Now %rax contains the entry point of the function being called. */
124 movq %rax,0x60(%rsp) # Store target over reloff argument
125 popq %r11 # Restore %r11
126 .cfi_adjust_cfa_offset -8
128 popq %r10 # Restore %r10
129 .cfi_adjust_cfa_offset -8
131 popq %r9 # Restore %r9
132 .cfi_adjust_cfa_offset -8
134 popq %r8 # Restore %r8
135 .cfi_adjust_cfa_offset -8
137 popq %rdi # Restore %rdi
138 .cfi_adjust_cfa_offset -8
140 popq %rsi # Restore %rsi
141 .cfi_adjust_cfa_offset -8
143 popq %rcx # Restore %rcx
144 .cfi_adjust_cfa_offset -8
146 popq %rdx # Restore %rdx
147 .cfi_adjust_cfa_offset -8
149 popq %rax # Restore %rax
150 .cfi_adjust_cfa_offset -8
152 popfq # Restore rflags
153 .cfi_adjust_cfa_offset -8
154 leaq 16(%rsp),%rsp # Discard spare, obj, do not change rflags
155 ret # "Return" to target address
157 .size _rtld_bind_start, . - _rtld_bind_start
159 .section .note.GNU-stack,"",%progbits