1/*- 2 * Copyright (c) 2014 The FreeBSD Foundation 3 * All rights reserved. 4 * 5 * This software was developed by Andrew Turner under 6 * sponsorship from the FreeBSD Foundation. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30#include <machine/asm.h> 31__FBSDID("$FreeBSD$"); 32 33ENTRY(.rtld_start) 34 mov x19, x0 /* Put ps_strings in a callee-saved register */ 35 mov x20, sp /* And the stack pointer */ 36 37 /* Handle the old style stack */ 38 /* TODO: Remove this when the kernel correctly aligns the stack */ 39 cbnz x0, 1f 40 mov x0, sp /* sp points to the args */ 41 and sp, x0, #~0xf /* Align the stack as needed */ 42 431: sub sp, sp, #16 /* Make room for obj_main & exit proc */ 44 45 mov x1, sp /* exit_proc */ 46 add x2, x1, #8 /* obj_main */ 47 bl _rtld /* Call the loader */ 48 mov x8, x0 /* Backup the entry point */ 49 50 ldr x2, [sp] /* Load cleanup */ 51 ldr x1, [sp, #8] /* Load obj_main */ 52 mov x0, x19 /* Restore ps_strings */ 53 mov sp, x20 /* Restore the stack pointer */ 54 br x8 /* Jump to the entry point */ 55END(.rtld_start) 56 57/* 58 * sp + 0 = &GOT[x + 3] 59 * sp + 8 = RA 60 * x16 = &GOT[2] 61 * x17 = &_rtld_bind_start 62 */ 63ENTRY(_rtld_bind_start) 64 mov x17, sp 65 66 /* Save the arguments */ 67 stp x0, x1, [sp, #-16]! 68 stp x2, x3, [sp, #-16]! 69 stp x4, x5, [sp, #-16]! 70 stp x6, x7, [sp, #-16]! 71 72 /* Calculate reloff */ 73 ldr x2, [x17, #0] /* Get the address of the entry */ 74 sub x1, x2, x16 /* Find its offset */ 75 sub x1, x1, #8 /* Adjust for x16 not being at offset 0 */ 76 /* Each rela item has 3 entriesso we need reloff = 3 * index */ 77 lsl x3, x1, #1 /* x3 = 2 * offset */ 78 add x1, x1, x3 /* x1 = x3 + offset = 3 * offset */ 79 80 /* Load obj */ 81 ldr x0, [x16, #-8] 82 83 /* Call into rtld */ 84 bl _rtld_bind 85 86 /* Restore the registers saved by the plt code */ 87 ldp xzr, x30, [sp, #(4 * 16)] 88 89 /* Backup the address to branch to */ 90 mov x16, x0 91 92 /* restore the arguments */ 93 ldp x6, x7, [sp], #16 94 ldp x4, x5, [sp], #16 95 ldp x2, x3, [sp], #16 96 ldp x0, x1, [sp], #16 97 /* And the part of the stack the plt entry handled */ 98 add sp, sp, #16 99 100 /* Call into the correct function */ 101 br x16 102END(_rtld_bind_start) 103 104/* 105 * uint64_t _rtld_tlsdesc(struct tlsdesc *); 106 * 107 * struct tlsdesc { 108 * uint64_t ptr; 109 * uint64_t data; 110 * }; 111 * 112 * Returns the data. 113 */ 114ENTRY(_rtld_tlsdesc) 115 ldr x0, [x0, #8] 116 ret 117END(_rtld_tlsdesc) 118 119/* 120 * uint64_t _rtld_tlsdesc_dynamic(struct tlsdesc *); 121 * 122 * TODO: We could lookup the saved index here to skip saving the entire stack. 123 */ 124ENTRY(_rtld_tlsdesc_dynamic) 125 /* Store any registers we may use in rtld_tlsdesc_handle */ 126 stp x29, x30, [sp, #-(10 * 16)]! 127 mov x29, sp 128 stp x1, x2, [sp, #(1 * 16)] 129 stp x3, x4, [sp, #(2 * 16)] 130 stp x5, x6, [sp, #(3 * 16)] 131 stp x7, x8, [sp, #(4 * 16)] 132 stp x9, x10, [sp, #(5 * 16)] 133 stp x11, x12, [sp, #(6 * 16)] 134 stp x13, x14, [sp, #(7 * 16)] 135 stp x15, x16, [sp, #(8 * 16)] 136 stp x17, x18, [sp, #(9 * 16)] 137 138 /* Find the tls offset */ 139 ldr x0, [x0, #8] 140 mov x1, #1 141 bl rtld_tlsdesc_handle 142 143 /* Restore the registers */ 144 ldp x17, x18, [sp, #(9 * 16)] 145 ldp x15, x16, [sp, #(8 * 16)] 146 ldp x13, x14, [sp, #(7 * 16)] 147 ldp x11, x12, [sp, #(6 * 16)] 148 ldp x9, x10, [sp, #(5 * 16)] 149 ldp x7, x8, [sp, #(4 * 16)] 150 ldp x5, x6, [sp, #(3 * 16)] 151 ldp x3, x4, [sp, #(2 * 16)] 152 ldp x1, x2, [sp, #(1 * 16)] 153 ldp x29, x30, [sp], #(10 * 16) 154 155 ret 156END(_rtld_tlsdesc_dynamic) 157