rtld_start.S revision 1.3
1 /* $NetBSD: rtld_start.S,v 1.3 2018/09/20 18:41:05 jakllsch Exp $ */ 2 3 /*- 4 * Copyright (c) 2014 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Matt Thomas of 3am Software Foundry. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /*- 33 * Copyright (c) 2014 The FreeBSD Foundation 34 * All rights reserved. 35 * 36 * This software was developed by Andrew Turner under 37 * sponsorship from the FreeBSD Foundation. 38 * 39 * Redistribution and use in source and binary forms, with or without 40 * modification, are permitted provided that the following conditions 41 * are met: 42 * 1. Redistributions of source code must retain the above copyright 43 * notice, this list of conditions and the following disclaimer. 44 * 2. Redistributions in binary form must reproduce the above copyright 45 * notice, this list of conditions and the following disclaimer in the 46 * documentation and/or other materials provided with the distribution. 47 * 48 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 49 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 50 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 51 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 52 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 53 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 54 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 55 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 56 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 57 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 58 * SUCH DAMAGE. 59 */ 60 61 #include <machine/asm.h> 62 63 RCSID("$NetBSD: rtld_start.S,v 1.3 2018/09/20 18:41:05 jakllsch Exp $") 64 65 /* 66 * void _rtld_start(void (*cleanup)(void), const Obj_Entry *obj, 67 * struct ps_strings *ps_strings); 68 * 69 * X0 = NULL 70 * X1 = NULL 71 * X2 = ps_strings 72 * X30 (LR) = 0 73 * X29 (FP) = 0 74 */ 75 ENTRY_NP(_rtld_start) 76 mov x24, x2 /* save ps_strings */ 77 78 adrp x1, :got:_DYNAMIC /* load _DYNAMIC offset from GOT */ 79 ldr x1, [x1, #:got_lo12:_DYNAMIC] 80 81 adrp x0, _DYNAMIC /* get &_DYNAMIC */ 82 add x0, x0, #:lo12:_DYNAMIC 83 84 sub x25, x0, x1 /* relocbase = &_DYNAMIC - GOT:_DYNAMIC */ 85 mov x1, x25 /* pass as 2nd argument */ 86 bl _C_LABEL(_rtld_relocate_nonplt_self) 87 88 sub sp, sp, #16 /* reserve space for returns */ 89 mov x0, sp /* pointer to reserved space */ 90 mov x1, x25 /* pass relocbase */ 91 bl _C_LABEL(_rtld) 92 mov x17, x0 /* save entry point */ 93 94 ldp x0, x1, [sp], #16 /* pop cleanup & obj_main */ 95 mov x2, x24 /* restore ps_strings */ 96 97 br x17 /* call saved entry point */ 98 END(_rtld_start) 99 100 /* 101 * Upon entry from plt0 entry: 102 * 103 * SP+0 = &PLTGOT[n + 3] 104 * SP+8 = return addr 105 * X16 = &PLTGOT[2] 106 */ 107 ENTRY_NP(_rtld_bind_start) 108 ldr x9, [sp] /* x9 = &PLTGOT[n+3] */ 109 110 /* save x0-x8 for arguments */ 111 stp x0, x1, [sp, #-16]! 112 stp x2, x3, [sp, #-16]! 113 stp x4, x5, [sp, #-16]! 114 stp x6, x7, [sp, #-16]! 115 stp x8, xzr, [sp, #-16]! 116 117 /* save q0-q7 for arguments */ 118 stp q0, q1, [sp, #-32]! 119 stp q2, q3, [sp, #-32]! 120 stp q4, q5, [sp, #-32]! 121 stp q6, q7, [sp, #-32]! 122 123 ldr x0, [x16, #-8] /* x0 = PLTGOT[1] */ 124 sub x1, x9, x16 /* x1 = &PLTGOT[n+3] - &PLTGOT[1] = offset+8 */ 125 sub x1, x1, #8 /* x1 = offset */ 126 lsr x1, x1, #3 /* x1 /= sizeof(void *) */ 127 128 bl _C_LABEL(_rtld_bind) 129 mov x17, x0 /* save result */ 130 131 /* restore q0-q7 for arguments */ 132 ldp q6, q7, [sp], #32 133 ldp q4, q5, [sp], #32 134 ldp q2, q3, [sp], #32 135 ldp q0, q1, [sp], #32 136 137 /* restore x0-x8 for arguments */ 138 ldp x8, xzr, [sp], #16 139 ldp x6, x7, [sp], #16 140 ldp x4, x5, [sp], #16 141 ldp x2, x3, [sp], #16 142 ldp x0, x1, [sp], #16 143 144 ldp xzr, lr, [sp], #16 /* restore original lr pushed by plt0 */ 145 br x17 /* call bound function */ 146 END(_rtld_bind_start) 147 148 149 ENTRY(_rtld_tlsdesc) 150 ldr x0, [x0, #8] 151 ret 152 END(_rtld_tlsdesc) 153 154 /* 155 * uint64_t _rtld_tlsdesc_dynamic(struct tlsdesc *); 156 * 157 * TODO: We could lookup the saved index here to skip saving the entire stack. 158 */ 159 ENTRY(_rtld_tlsdesc_dynamic) 160 /* Store any registers we may use in rtld_tlsdesc_handle */ 161 stp x29, x30, [sp, #-(10 * 16)]! 162 mov x29, sp 163 stp x1, x2, [sp, #(1 * 16)] 164 stp x3, x4, [sp, #(2 * 16)] 165 stp x5, x6, [sp, #(3 * 16)] 166 stp x7, x8, [sp, #(4 * 16)] 167 stp x9, x10, [sp, #(5 * 16)] 168 stp x11, x12, [sp, #(6 * 16)] 169 stp x13, x14, [sp, #(7 * 16)] 170 stp x15, x16, [sp, #(8 * 16)] 171 stp x17, x18, [sp, #(9 * 16)] 172 173 /* Find the tls offset */ 174 ldr x0, [x0, #8] 175 mov x1, #1 176 bl _rtld_tlsdesc_handle 177 178 /* Restore the registers */ 179 ldp x17, x18, [sp, #(9 * 16)] 180 ldp x15, x16, [sp, #(8 * 16)] 181 ldp x13, x14, [sp, #(7 * 16)] 182 ldp x11, x12, [sp, #(6 * 16)] 183 ldp x9, x10, [sp, #(5 * 16)] 184 ldp x7, x8, [sp, #(4 * 16)] 185 ldp x5, x6, [sp, #(3 * 16)] 186 ldp x3, x4, [sp, #(2 * 16)] 187 ldp x1, x2, [sp, #(1 * 16)] 188 ldp x29, x30, [sp], #(10 * 16) 189 190 ret 191 END(_rtld_tlsdesc_dynamic) 192
Indexes created Tue Oct 07 21:09:53 GMT 2025