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rtld_start.S revision 1.3 
      1 /*	$NetBSD: rtld_start.S,v 1.3 2022/12/03 09:39:44 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 /*
     38  * void
     39  * ___start(void (*cleanup)(void),
     40  *     const Obj_Entry *obj,
     41  *     struct ps_strings *ps_strings)
     42  */
     43 ENTRY(_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);
     70 END(_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  */
     87 ENTRY_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
    116 END(_rtld_bind_start)
    117