rtld_start.S revision 117211
1/* $NetBSD: rtld_start.S,v 1.5 2001/08/14 22:17:48 eeh Exp $ */ 2 3/*- 4 * Copyright (c) 2001 Jake Burkholder. 5 * Copyright (c) 2000 Eduardo Horvath. 6 * Copyright (c) 1999 The NetBSD Foundation, Inc. 7 * All rights reserved. 8 * 9 * This code is derived from software contributed to The NetBSD Foundation 10 * by Christos Zoulas and Paul Kranenburg. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the NetBSD 23 * Foundation, Inc. and its contributors. 24 * 4. Neither the name of The NetBSD Foundation nor the names of its 25 * contributors may be used to endorse or promote products derived 26 * from this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 29 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 30 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 31 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 32 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 33 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 34 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 35 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 36 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 37 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 38 * POSSIBILITY OF SUCH DAMAGE. 39 * 40 * $FreeBSD: head/libexec/rtld-elf/sparc64/rtld_start.S 117211 2003-07-04 00:05:15Z jake $ 41 */ 42 43#include <machine/asm.h> 44 45/* 46 * ELF: 47 * On startup the stack should contain 16 extended word register save 48 * area, followed by the arg count, etc. 49 */ 50 51ENTRY(.rtld_start) 52 clr %fp 53 mov %o0, %l0 54 mov %o3, %l1 55 56 sub %sp, 16, %sp 57 add %sp, SPOFF + CCFSZ + 0x0, %o1 58 call _rtld 59 add %sp, SPOFF + CCFSZ + 0x8, %o2 60 61 ldx [%sp + SPOFF + CCFSZ + 0x0], %o1 62 ldx [%sp + SPOFF + CCFSZ + 0x8], %o2 63 add %sp, 16, %sp 64 65 mov %l1, %o3 66 jmp %o0 67 mov %l0, %o0 68END(.rtld_start) 69 70/* 71 * Find the address of _DYNAMIC by disassembling a call instruction to it. 72 * Binutils may not fill in the GOT as expected on other architectures. 73 */ 74 75ENTRY(rtld_dynamic) 76 save %sp, -CCFSZ, %sp 77 call 1f 78 nop 79 call _DYNAMIC + 8 801: lduw [%o7 + 8], %o0 81 sll %o0, 2, %o0 82 sra %o0, 0, %o0 83 ret 84 restore %o0, %o7, %o0 85END(rtld_dynamic) 86 87 /* 88 * We have two separate entry points to the runtime linker. 89 * I'm implementing this following the SPARC v9 ABI spec. 90 * 91 * _rtld_bind_start_0(x, y) is called from .PLT0, and is used for 92 * PLT entries above 32768. 93 * 94 * _rtld_bind_start_1(x, y) is called from .PLT1, and is used for 95 * PLT entries below 32768. 96 * 97 * The first two entries of PLT2 contain the xword object pointer. 98 * 99 * These routines are called with two longword arguments, 100 * x and y. To calculate the address of the entry, 101 * _rtld_bind_start_1(x, y) does: 102 * 103 * n = x >> 15; 104 * 105 * and _rtld_bind_start_0(x, y) should do, according to the SCD: 106 * 107 * i = x - y - 1048596; 108 * n = 32768 + (i/5120)*160 + (i%5120)/24; 109 * 110 * Note that the number of 1048596 from above is incorrect; rather, 111 * we need to use HIPLTOFFS as defined below. 112 * 113 * Neither routine needs to issue a save since it's already been 114 * done in the PLT entry. 115 */ 116 117#define NPLTLOSLOTS 32768 118#define PLTSLOTSZ 32 119/* 120 * - 16 to compensate for the difference of the positions of the jumps that 121 * generate the arguments in .PLT0 and the high plt entry. 122 */ 123#define HIPLTOFFS (NPLTLOSLOTS * PLTSLOTSZ - 16) 124 125ENTRY(_rtld_bind_start_0) 126 sethi %hi(HIPLTOFFS), %l1 127 or %l1, %lo(HIPLTOFFS), %l1 128 sub %o0, %o1, %l0 /* x - y */ 129 sub %l0, %l1, %l0 /* i = x - y - HIPLTOFFS */ 130 sethi %hi(5120), %l7 131 sdivx %l0, %l7, %l1 /* Calculate i / 5120 */ 132 mulx %l1, %l7, %l3 133 sub %l0, %l3, %l2 /* And i % 5120 */ 134 mulx %l1, 160, %l5 /* (i / 5120) * 160 */ 135 sdivx %l2, 24, %l4 /* (i % 5120) / 24 */ 136 sethi %hi(NPLTLOSLOTS), %l6 137 add %l4, %l5, %l4 /* (i / 5120) * 160 + (i % 5120) / 24 */ 138 add %l4, %l6, %l4 /* + NPLTLOSLOTS */ 139 sub %l4, 4, %l4 /* XXX: 4 entries are reserved */ 140 141 sllx %l4, 1, %l5 /* Each element is an Elf_Rela which */ 142 add %l5, %l4, %l4 /* is 3 longwords or 24 bytes. */ 143 sllx %l4, 3, %l4 /* So multiply by 24. */ 144 145 ldx [%o1 + (10*4)], %o0 /* Load object pointer from PLT2 */ 146 147 call _rtld_bind /* Call _rtld_bind(obj, offset) */ 148 mov %l4, %o1 149 150 jmp %o0 /* return value == function address */ 151 restore /* Dump our stack frame */ 152END(_rtld_bind_start_0) 153 154ENTRY(_rtld_bind_start_1) 155 srax %o0, 15, %o2 /* %o0 is the index to our PLT slot */ 156 sub %o2, 4, %o2 /* XXX: 4 entries are reserved */ 157 158 sllx %o2, 1, %o3 /* Each element is an Elf_Rela which */ 159 add %o3, %o2, %o2 /* is 3 longwords or 24 bytes. */ 160 sllx %o2, 3, %o2 /* So multiply by 24. */ 161 162 ldx [%o1 + 8], %o0 /* The object pointer is at [%o1 + 8] */ 163 164 call _rtld_bind /* Call _rtld_bind(obj, offset) */ 165 mov %o2, %o1 166 167 jmp %o0 /* return value == function address */ 168 restore /* Dump our stack frame */ 169END(_rtld_bind_start_1) 170