1/* $NetBSD: rtld_start.S,v 1.6 2023/05/07 12:41:48 skrll 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#define PTRSZ __SIZEOF_POINTER__ 38 39/* 40 * void 41 * ___start( 42 * void (*cleanup)(void), 43 * struct ps_strings *ps_strings 44 * ) 45 */ 46 47ENTRY(_rtld_start) 48 mv s0, sp # save stack pointer 49 addi sp, sp, -4 * PTRSZ # adjust stack pointer 50 # -> 2 * PTR_SIZE(sp) for atexit 51 # -> 3 * PTR_SIZE(sp) for obj_main 52 mv s1, a1 # save ps_strings pointer 53 54.L0: auipc gp, %pcrel_hi(_GLOBAL_OFFSET_TABLE_) 55 PTR_L t0, %pcrel_lo(.L0)(gp) # &_DYNAMIC 56.L1: auipc a0, %pcrel_hi(_DYNAMIC) 57 addi a0, a0, %pcrel_lo(.L1) 58 sub s2, a0, t0 # save for _rtld 59 mv a1, s2 60 call _C_LABEL(_rtld_relocate_nonplt_self) 61 62 mv a1, s2 # relocbase 63 addi a0, sp, 2 * PTRSZ # sp 64 call _C_LABEL(_rtld) # a0 = _rtld(sp, relocbase) 65 mv t0, a0 66 67 PTR_L a0, 2 * PTRSZ(sp) # cleanup function 68// PTR_L a1, 3 * PTRSZ(sp) # obj_main pointer (not used) 69 mv a1, s1 # restore ps_strings 70 mv sp, s0 # restore stack pointer 71 mv s0, zero # break stack chain 72 jr t0 # _start(cleanup, ps_strings); 73END(_rtld_start) 74 75/* 76 * Needs to be 12 so that stack alignment is preserved on both RV32 and RV64. 77 */ 78 79#define XCALLFRAME_SIZ (12 * SZREG) 80#define XCALLFRAME_RA ( 8 * SZREG) 81#define XCALLFRAME_A7 ( 7 * SZREG) 82#define XCALLFRAME_A6 ( 6 * SZREG) 83#define XCALLFRAME_A5 ( 5 * SZREG) 84#define XCALLFRAME_A4 ( 4 * SZREG) 85#define XCALLFRAME_A3 ( 3 * SZREG) 86#define XCALLFRAME_A2 ( 2 * SZREG) 87#define XCALLFRAME_A1 ( 1 * SZREG) 88#define XCALLFRAME_A0 ( 0 * SZREG) 89 90/* 91 * t0 = obj pointer 92 * t1 = reloc offset 93 */ 94ENTRY_NP(_rtld_bind_start) 95 addi sp, sp, -XCALLFRAME_SIZ // save arguments on stack 96 REG_S a0, XCALLFRAME_A0(sp) 97 REG_S a1, XCALLFRAME_A1(sp) 98 REG_S a2, XCALLFRAME_A2(sp) 99 REG_S a3, XCALLFRAME_A3(sp) 100 REG_S a4, XCALLFRAME_A4(sp) 101 REG_S a5, XCALLFRAME_A5(sp) 102 REG_S a6, XCALLFRAME_A6(sp) 103 REG_S a7, XCALLFRAME_A7(sp) 104 REG_S ra, XCALLFRAME_RA(sp) 105 106 mv a0, t0 /* object from got.plt[1] */ 107 mv a1, t1 /* reloc offset */ 108 109 call _C_LABEL(_rtld_bind) 110 mv t0, a0 /* save function pointer */ 111 112 REG_L a0, XCALLFRAME_A0(sp) 113 REG_L a1, XCALLFRAME_A1(sp) 114 REG_L a2, XCALLFRAME_A2(sp) 115 REG_L a3, XCALLFRAME_A3(sp) 116 REG_L a4, XCALLFRAME_A4(sp) 117 REG_L a5, XCALLFRAME_A5(sp) 118 REG_L a6, XCALLFRAME_A6(sp) 119 REG_L a7, XCALLFRAME_A7(sp) 120 REG_L ra, XCALLFRAME_RA(sp) 121 addi sp, sp, XCALLFRAME_SIZ 122 jr t0 123END(_rtld_bind_start) 124