ldasm.S revision 1.7
1/* $OpenBSD: ldasm.S,v 1.7 2018/10/01 22:53:48 mortimer Exp $ */ 2 3/* 4 * Copyright (c) 2016 Dale Rahn 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 19 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 */ 28 29#define DL_DATA_SIZE (16 * 8) /* XXX */ 30#include <machine/asm.h> 31#include <sys/syscall.h> 32 33ENTRY(_dl_start) 34 mov x29, sp 35 // need to worry about alignment, I think not? 36 mov x19, sp 37 sub sp, sp, #8+8+DL_DATA_SIZE // dl_data size 38 add x20, sp, #4 // dl_data 39 mov x21, lr // save old lr 40 41 mov x0, x29 // original stack 42 mov x1, x20 // dl_data 43 44 adrp x2, _DYNAMIC /* &_DYNAMIC */ 45 add x2, x2, #:lo12:_DYNAMIC 46 47 bl _dl_boot_bind 48 49 add x0, x29, #8 // argv 50 ldr x1, [x29] // load argc 51 add x1, x0, x1, lsl #3 // envp = argv + argc * 8 52 add x1, x1, #8 // + 8 53 ldr x2, [x20, #7*8] // loff from dl_data 54 mov x3, x20 // dl_data 55 bl _dl_boot 56 57 mov sp, x29 // move stack back 58 mov x29, xzr // clear frame back pointer 59 mov lr, xzr 60 61 adrp x8, :got:_dl_dtors 62 ldr x2, [x8, :got_lo12:_dl_dtors] 63 64 br x0 65 66ENTRY(_dl_bind_start) 67 /* 68 * x16 is pointer to pltgot[2] 69 * x17 is available as scratch register 70 * return address and pointer to pltgot entry for this 71 * relocation are on the stack 72 */ 73 mov x17, sp 74 75 // save parameter/result registers 76 stp x0, x1, [sp, #-16]! 77 stp x2, x3, [sp, #-16]! 78 stp x4, x5, [sp, #-16]! 79 stp x6, x7, [sp, #-16]! 80 stp x8, xzr, [sp, #-16]! 81 82 /* 83 * no need to save v0-v9 as ld.so is compiled with 84 * -march=armv8-a+nofp+nosimd and therefore doesn't touch the 85 * SIMD and Floating-Point registers 86 */ 87 88 ldr x0, [x16, #-8] // object 89 ldr x2, [x17] 90 sub x1, x2, x16 91 sub x1, x1, #8 92 lsr x1, x1, #3 // relidx 93 bl _dl_bind 94 mov x17, x0 95 96 // restore parameter/result registers 97 ldp x8, xzr, [sp], #16 98 ldp x6, x7, [sp], #16 99 ldp x4, x5, [sp], #16 100 ldp x2, x3, [sp], #16 101 ldp x0, x1, [sp], #16 102 103 // restore LR saved by PLT stub 104 ldp xzr, x30, [sp], #16 105 br x17 106 107ENTRY(_rtld_tlsdesc) 108 RETGUARD_SETUP(_rtld_tlsdesc, x15) 109 ldr x0, [x0, #8] 110 RETGUARD_CHECK(_rtld_tlsdesc, x15) 111 ret 112