1/* $NetBSD: rtld_start.S,v 1.2 2015/03/27 23:14:53 matt 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#include <machine/asm.h> 33 34 .globl _C_LABEL(_rtld_relocate_nonplt_self) 35 .globl _C_LABEL(_rtld) 36 37/* 38 * void 39 * ___start(void (*cleanup)(void), 40 * const Obj_Entry *obj, 41 * struct ps_strings *ps_strings) 42 */ 43ENTRY(_rtld_start) 44 move s0, sp # save stack pointer 45 addi sp, sp, -4*__SIZEOF_POINTER__ 46 # adjust stack pointer 47 # -> 2*PTR_SIZE(sp) for atexit 48 # -> 3*PTR_SIZE(sp) for obj_main 49 move s1, a2 # save ps_strings pointer 50 51.L0: auipc gp, %pcrel_hi(_GLOBAL_OFFSET_TABLE_) 52 PTR_L t0, %pcrel_lo(.L0)(gp) # &_DYNAMIC 53.L1: auipc a0, %pcrel_hi(_DYNAMIC) 54 addi a0, a0, %pcrel_lo(.L1) 55 sub s2, a0, t0 # save for _rtld 56 move a1, s2 57 call _C_LABEL(_rtld_relocate_nonplt_self) 58 59 move a1, s2 # relocbase 60 addi a0, sp, 2*__SIZEOF_POINTER__ # sp 61 call _C_LABEL(_rtld) # a0 = _rtld(sp, relocbase) 62 mv t0, a0 63 64 PTR_L a0, 2*__SIZEOF_POINTER__(sp) # cleanup function 65 PTR_L a1, 3*__SIZEOF_POINTER__(sp) # obj_main entry 66 move a2, s1 # restore ps_strings 67 move sp, s0 # readjust stack 68 move s0, zero # break stack chain 69 jr t0 # _start(cleanup, obj_main, ps_strings); 70END(_rtld_start) 71 72#define XCALLFRAME_SIZ (12*SZREG) 73#define XCALLFRAME_RA (8*SZREG) 74#define XCALLFRAME_A7 (7*SZREG) 75#define XCALLFRAME_A6 (6*SZREG) 76#define XCALLFRAME_A5 (5*SZREG) 77#define XCALLFRAME_A4 (4*SZREG) 78#define XCALLFRAME_A3 (3*SZREG) 79#define XCALLFRAME_A2 (2*SZREG) 80#define XCALLFRAME_A1 (1*SZREG) 81#define XCALLFRAME_A0 (0*SZREG) 82 83/* 84 * t0 = obj pointer 85 * t1 = reloc offset 86 */ 87ENTRY_NP(_rtld_bind_start) 88 addi sp, sp, -XCALLFRAME_SIZ // save arguments on stack 89 REG_S a0, XCALLFRAME_A0(sp) 90 REG_S a1, XCALLFRAME_A1(sp) 91 REG_S a2, XCALLFRAME_A2(sp) 92 REG_S a3, XCALLFRAME_A3(sp) 93 REG_S a4, XCALLFRAME_A4(sp) 94 REG_S a5, XCALLFRAME_A5(sp) 95 REG_S a6, XCALLFRAME_A6(sp) 96 REG_S a7, XCALLFRAME_A7(sp) 97 REG_S ra, XCALLFRAME_RA(sp) 98 99 mv a0, t0 /* object from got.plt[1] */ 100 mv a1, t1 /* reloc offset */ 101 102 call _C_LABEL(_rtld_bind) 103 mv t0, a0 /* save function pointer */ 104 105 REG_L a0, XCALLFRAME_A0(sp) 106 REG_L a1, XCALLFRAME_A1(sp) 107 REG_L a2, XCALLFRAME_A2(sp) 108 REG_L a3, XCALLFRAME_A3(sp) 109 REG_L a4, XCALLFRAME_A4(sp) 110 REG_L a5, XCALLFRAME_A5(sp) 111 REG_L a6, XCALLFRAME_A6(sp) 112 REG_L a7, XCALLFRAME_A7(sp) 113 REG_L ra, XCALLFRAME_RA(sp) 114 addi sp, sp, XCALLFRAME_SIZ 115 jr t0 116END(_rtld_bind_start) 117