1/* $NetBSD: rtld_start.S,v 1.4 2001/09/26 04:06:43 mycroft Exp $ */ 2 3/*- 4 * Copyright (C) 1998 Tsubai Masanari 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 * 29 * $FreeBSD$ 30 */ 31 32#include <machine/asm.h> 33 34.extern _GLOBAL_OFFSET_TABLE_ 35.extern _DYNAMIC 36 37_ENTRY(_rtld_start) 38 stdu %r1,-144(%r1) /* 16-byte aligned stack for reg saves + 39 exit_proc & obj _rtld args + 40 backchain & lrsave stack frame */ 41 std %r3,96(%r1) /* argc */ 42 std %r4,104(%r1) /* argv */ 43 std %r5,112(%r1) /* envp */ 44/* std %r6,120(%r1) *//* obj (always 0) */ 45/* std %r7,128(%r1) *//* cleanup (always 0) */ 46 std %r8,136(%r1) /* ps_strings */ 47 48 /* 49 * Perform initial relocation of ld-elf.so. Not as easy as it 50 * sounds. 51 * - perform small forward branch to put PC into link reg 52 * - use link-time constants to determine offset to the 53 * _DYNAMIC section and the GOT. Add these to the PC to 54 * convert to absolute addresses. 55 * - call reloc_non_plt_self() to fix up ld-elf.so's relocations 56 */ 57 58 bl 1f 59 .llong _DYNAMIC-. 601: 61 mflr %r3 /* PC value at .llong */ 62 ld %r4,0(%r3) /* offset to _DYNAMIC */ 63 add %r3,%r4,%r3 /* r3 = &_DYNAMIC, absolute value */ 64 65 ld %r4,-0x8000(%r2) /* First TOC entry is TOC base */ 66 subf %r4,%r4,%r2 /* Subtract from real TOC base to get base */ 67 68 bl reloc_non_plt_self /* reloc_non_plt_self(&_DYNAMIC,base) */ 69 nop 70 71 /* 72 * The _rtld() function likes to see a stack layout containing 73 * { argc, argv[0], argv[1] ... argv[N], 0, env[0], ... , env[N] } 74 * Since the PowerPC stack was 16-byte aligned at exec time, the 75 * original stack layout has to be found by moving back a word 76 * from the argv pointer. 77 */ 78 ld %r4,104(%r1) 79 addi %r3,%r4,-8 /* locate argc ptr, &argv[-1] */ 80 addi %r4,%r1,128 /* &exit_proc on stack */ 81 addi %r5,%r1,120 /* &obj_main on stack */ 82 83 bl _rtld /* &_start = _rtld(sp, &exit_proc, &obj_main)*/ 84 nop 85#if !defined(_CALL_ELF) || _CALL_ELF == 1 86 ld %r2,8(%r3) 87 ld %r11,16(%r3) 88 ld %r3,0(%r3) 89#else 90 mr %r12,%r3 91#endif 92 mtlr %r3 93 94 /* 95 * Restore args, with new obj/exit proc 96 */ 97 ld %r3,96(%r1) /* argc */ 98 ld %r4,104(%r1) /* argv */ 99 ld %r5,112(%r1) /* envp */ 100 ld %r6,120(%r1) /* obj */ 101 ld %r7,128(%r1) /* exit proc */ 102 ld %r8,136(%r1) /* ps_strings */ 103 104 blrl /* _start(argc, argv, envp, obj, cleanup, ps_strings) */ 105 106 li %r0,1 /* _exit() */ 107 sc 108 109/* 110 * _rtld_bind_start() 111 * 112 * Call into the MI binder. This routine is reached via the PLT call cell 113 * 114 * On entry, %r11 contains an object pointer and %r0 contains the PLT index. 115 * 116 * Save all registers, call into the binder to resolve and fixup the external 117 * routine, and then transfer to the external routine on return. 118 */ 119 .globl _rtld_bind 120 121_ENTRY(_rtld_bind_start) 122 mr %r12,%r0 # save r0 (index) immediately to r12 123 mflr %r0 124 std %r0,16(%r1) # save lr 125 mfcr %r0 126 std %r0,8(%r1) # save cr 127 128 stdu %r1,-48-12*8(%r1) # stack space for 8 regs + header 129 # + 2 save regs 130 std %r3,64+0*8(%r1) # save r3-r10 (arguments) 131 std %r4,64+1*8(%r1) 132 std %r5,64+2*8(%r1) 133 std %r6,64+3*8(%r1) 134 std %r7,64+4*8(%r1) 135 std %r8,64+5*8(%r1) 136 std %r9,64+6*8(%r1) 137 std %r10,64+7*8(%r1) 138 139 mr %r3,%r11 140 mulli %r4,%r12,24 # Multiply index by sizeof(Elf_Rela) 141 142 bl _rtld_bind # target addr = _rtld_bind(obj, reloff) 143 nop 144 145#if !defined(_CALL_ELF) || _CALL_ELF == 1 146 ld %r2,8(%r3) 147 ld %r11,16(%r3) 148 ld %r3,0(%r3) 149#else 150 mr %r12,%r3 151#endif 152 mtctr %r3 # move absolute target addr into ctr 153 154 ld %r3,64+0*8(%r1) # restore r3-r10 155 ld %r4,64+1*8(%r1) 156 ld %r5,64+2*8(%r1) 157 ld %r6,64+3*8(%r1) 158 ld %r7,64+4*8(%r1) 159 ld %r8,64+5*8(%r1) 160 ld %r9,64+6*8(%r1) 161 ld %r10,64+7*8(%r1) 162 163 ld %r1,0(%r1) # restore stack 164 ld %r0,8(%r1) # restore cr 165 mtcr %r0 166 ld %r0,16(%r1) # restore lr 167 mtlr %r0 168 169 bctr # jump to target 170 171 .section .note.GNU-stack,"",%progbits 172