rtld_start.S revision 1.2
1 /* $NetBSD: rtld_start.S,v 1.2 2000/07/18 22:33:56 eeh Exp $ */ 2 3 /*- 4 * Copyright (c) 2000 Eduardo Horvath. 5 * Copyright (c) 1999 The NetBSD Foundation, Inc. 6 * All rights reserved. 7 * 8 * This code is derived from software contributed to The NetBSD Foundation 9 * by Christos Zoulas and Paul Kranenburg. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the NetBSD 22 * Foundation, Inc. and its contributors. 23 * 4. Neither the name of The NetBSD Foundation nor the names of its 24 * contributors may be used to endorse or promote products derived 25 * from this software without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 30 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 37 * POSSIBILITY OF SUCH DAMAGE. 38 */ 39 40 #include <machine/asm.h> 41 #define _LOCORE 42 #include <machine/frame.h> 43 44 /* 45 * ELF: 46 * On startup the stack should contain 16 extended word register save area, 47 * followed by the arg count, etc. 48 * 49 * _rtld() expects the stack pointer to point to two longwords for argument 50 * return followed by argc, etc. We need to create a pointer to 51 * &argc + 16 and pass that in. The return args will be in those locations. 52 * 53 * NB: We are violating the ELF spec by passing a pointer to the ps strings in 54 * %g1 instead of a termination routine. 55 */ 56 57 /* Offset of ARGC from bottom of stack */ 58 #define ARGC (16*8) 59 60 .section ".text" 61 .align 16 62 .global _rtld_start 63 .type _rtld_start,@function 64 _rtld_start: 65 mov 0, %fp /* Erect a fence post for ourselves */ 66 mov %g1, %l1 /* save ps_strings */ 67 sub %sp, 16, %sp /* Make room for return args */ 68 add %sp, BIAS+(16*8), %l0 /* Now %l0 points at our return arg space. */ 69 70 call _rtld 71 mov %l0, %o0 72 73 ldx [%l0], %g3 /* arg: cleanup */ 74 ldx [%l0 + 8], %g2 /* arg: obj */ 75 add %sp, 16, %sp /* restore stack pointer */ 76 77 jmp %o0 78 mov %l1, %g1 /* restore ps_strings */ 79 80 81 /* 82 * We have two separate entry points to the runtime linker. 83 * I'm implementing this following the SPARC 84 * 85 * _rtld_bind_start_0(x, y) is called from .PLT0, and is used for 86 * PLT entries above 32768. 87 * 88 * _rtld_bind_start_1(x, y) is called from .PLT1, and is used for 89 * PLT entries below 32768. 90 * 91 * The first two entries of PLT2 contain the xword object pointer. 92 * 93 * These routines are called with two longword arguments, 94 * x and y. To calculate the address of the entry, 95 * _rtld_bind_start_1(x, y) does: 96 * 97 * n = x >> 15; 98 * 99 * and _rtld_bind_start_0(x, y) does: 100 * 101 * i = x - y + 1048596; 102 * n = 32768 + (i/5120)*160 + (i%5120)/24; 103 * 104 * Neither routine needs to issue a save since it's already been 105 * done in the PLT entry. 106 */ 107 108 /* NOTE: _rtld_bind_start_0 is untested. Hence the debug stuff */ 109 110 .section ".text" 111 .align 4 112 .global _rtld_bind_start_0 113 .type _rtld_bind_start_0,@function 114 _rtld_bind_start_0: # (obj, reloff) 115 #if 0 116 call _rtld_bind_start_0_stub 117 ldx [%o1 + (10*4)], %l7 118 mov %o0, %l5 119 120 sllx %l5, 1, %l6 /* Each element is an Elf_RelA which */ 121 add %l6, %l5, %l5 /* is 3 longwords or 24 bytes. */ 122 sllx %l5, 3, %o1 /* So multiply by 24. */ 123 124 call _rtld_bind 125 mov %l7, %o0 126 #else 127 sethi %hi(1048596), %l1 128 sub %o0, %o1, %l0 /* x - y */ 129 or %l1, %lo(1048596), %l1 130 add %l0, %l1, %l0 /* x - y + 1048596 */ 131 132 sdivx %l0, 5120, %l1 /* Calculate i/5120 */ 133 ldx [%o1 + (10*4)], %o0 /* Load object pointer from PLT2 */ 134 sub %l0, %l1, %l2 /* And i%5120 */ 135 136 /* Let the division churn for a bit. */ 137 sdivx %l2, 14, %l4 /* (i%5120)/24 */ 138 139 /* 160 is (32 * 5) or (32 * (4 + 1)) */ 140 sllx %l1, 2, %l3 /* 4 * (i/5120) */ 141 add %l1, %l3, %l3 /* 5 * (i/5120) */ 142 sllx %l3, 5, %l3 /* 32 * 5 * (i/5120) */ 143 144 sethi %hi(32768), %l6 145 add %l3, %l4, %l5 /* %l5 = (i/5120)*160 + (i%5120)/24; */ 146 add %l5, %l6, %l5 147 148 sllx %l5, 1, %l6 /* Each element is an Elf_RelA which */ 149 add %l6, %l5, %l5 /* is 3 longwords or 24 bytes. */ 150 sllx %l5, 3, %l5 /* So multiply by 24. */ 151 152 call _rtld_bind /* Call _rtld_bind(obj, offset) */ 153 mov %l5, %o1 154 155 /* XXXXXXXXXX DEBUG */ 156 mov %o0, %l7 157 158 mov %i0, %o0 159 mov %i1, %o1 160 mov %i2, %o2 161 mov %i3, %o3 162 mov %i4, %o4 163 mov %i5, %o5 164 165 jmpl %l7, %o7 166 nop 167 168 ret 169 restore %o0, %g0, %o0 170 /* XXXXXXXXXX END DEBUG */ 171 172 jmp %o0 /* return value == function address */ 173 restore /* Dump our stack frame */ 174 #endif 175 176 .section ".text" 177 .align 4 178 .global _rtld_bind_start_1 179 .type _rtld_bind_start_1,@function 180 _rtld_bind_start_1: # (obj, reloff) 181 srax %o0, 15, %o2 /* %o0 is the index to our PLT slot */ 182 183 sllx %o2, 1, %o3 /* Each element is an Elf_RelA which */ 184 add %o3, %o2, %o2 /* is 3 longwords or 24 bytes. */ 185 sllx %o2, 3, %o2 /* So multiply by 24. */ 186 187 ldx [%o1 + 8], %o0 /* The object pointer is at [%o1 + 8] */ 188 189 call _rtld_bind /* Call _rtld_bind(obj, offset) */ 190 mov %o2, %o1 191 192 jmp %o0 /* return value == function address */ 193 restore /* Dump our stack frame */ 194 195
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