rtld_start.S revision 1.1
1 /* $NetBSD: rtld_start.S,v 1.1 2000/07/13 23:14:18 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 42 /* 43 * ELF: 44 * On startup the stack should contain 16 extended word register save area, 45 * followed by the arg count, etc. 46 * 47 * _rtld() expects the stack pointer to point to two longwords for argument 48 * return followed by argc, etc. We need to create a pointer to 49 * &argc + 16 and pass that in. The return args will be in those locations. 50 * 51 * NB: We are violating the ELF spec by passing a pointer to the ps strings in 52 * %g1 instead of a termination routine. 53 */ 54 55 /* Offset of ARGC from bottom of stack */ 56 #define ARGC (16*8) 57 58 .section ".text" 59 .align 16 60 .global _rtld_start 61 .type _rtld_start,@function 62 _rtld_start: 63 mov 0, %fp /* Erect a fence post for ourselves */ 64 mov %g1, %l1 /* save ps_strings */ 65 sub %sp, 16, %sp /* Make room for return args */ 66 add %sp, BIAS+(16*8), %l0 /* Now %l0 points at our return arg space. */ 67 68 call _rtld 69 mov %l0, %o0 70 71 ldx [%l0], %g3 /* arg: cleanup */ 72 ldx [%l0 + 8], %g2 /* arg: obj */ 73 add %sp, 16, %sp /* restore stack pointer */ 74 75 jmp %o0 76 mov %l1, %g1 /* restore ps_strings */ 77 78 79 /* 80 * We have two separate entry points to the runtime linker. 81 * I'm implementing this following the SPARC 82 * 83 * _rtld_bind_start_0(x, y) is called from .PLT0, and is used for 84 * PLT entries above 32768. 85 * 86 * _rtld_bind_start_1(x, y) is called from .PLT1, and is used for 87 * PLT entries below 32768. 88 * 89 * The first two entries of PLT2 contain the xword object pointer. 90 * 91 * These routines are called with two longword arguments, 92 * x and y. To calculate the address of the entry, 93 * _rtld_bind_start_1(x, y) does: 94 * 95 * n = x >> 15; 96 * 97 * and _rtld_bind_start_0(x, y) does: 98 * 99 * i = x - y + 1048596; 100 * n = 32768 + (i/5120)*160 + (i%5120)/24; 101 * 102 * Neither routine needs to issue a save since it's already been 103 * done in the PLT entry. 104 */ 105 106 .section ".text" 107 .align 4 108 .global _rtld_bind_start 109 .type _rtld_bind_start,@function 110 _rtld_bind_start_0: # (obj, reloff) 111 sethi %hi(1048596), %l1 112 sub %o0, %o1, %l0 /* x - y */ 113 or %l1, %lo(1048596), %l1 114 add %l0, %l1, %l0 /* x - y + 1048596 */ 115 116 sdivx %l0, 5120, %l1 /* Calculate i/5120 */ 117 ldx [%o1 + (10*4)], %o0 /* Load object pointer from PLT2 */ 118 sub %l0, %l1, %l2 /* And i%5120 */ 119 120 /* Let the division churn for a bit. */ 121 sdivx %l2, 14, %l4 /* (i%5120)/24 */ 122 123 /* 160 is (32 * 5) or (32 * (4 + 1)) */ 124 sllx %l1, 2, %l3 /* 4 * (i/5120) */ 125 add %l1, %l3, %l3 /* 5 * (i/5120) */ 126 sllx %l3, 5, %l3 /* 32 * 5 * (i/5120) */ 127 128 sethi %hi(32768), %l6 129 add %l3, %l4, %l5 /* %l5 = (i/5120)*160 + (i%5120)/24; */ 130 add %l5, %l6, %l5 131 call _rtld_bind /* Call _rtld_bind(obj, offset) */ 132 sub %l5, 4, %o1 /* The first 4 entries are reserved. */ 133 jmp %o0 /* return value == function address */ 134 restore /* Dump our stack frame */ 135 136 137 .section ".text" 138 .align 4 139 .global _rtld_bind_start 140 .type _rtld_bind_start,@function 141 _rtld_bind_start_1: # (obj, reloff) 142 srax %o0, 15, %o2 /* %o0 points to our PLT slot */ 143 ldx [%o1 + 8], %o0 /* The object pointer is at [%o1 + 8] */ 144 call _rtld_bind /* Call _rtld_bind(obj, offset) */ 145 sub %o2, 4*32, %o1 /* The first 4 entries are reserved. */ 146 jmp %o0 /* return value == function address */ 147 restore /* Dump our stack frame */ 148 149
Indexes created Thu Oct 02 01:09:59 GMT 2025