1/*      $NetBSD: rtld_start.S,v 1.4 2001/09/26 04:06:43 mycroft Exp $   */
2
3/*-
4 * Copyright (C) 1998   Tsubai Masanari
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 *    derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * $FreeBSD$
30 */
31
32#include <machine/asm.h>
33
34.extern _GLOBAL_OFFSET_TABLE_
35.extern _DYNAMIC
36
37_ENTRY(_rtld_start)
38	stdu    %r1,-144(%r1)	/* 16-byte aligned stack for reg saves +
39				exit_proc & obj _rtld args +
40				backchain & lrsave stack frame */
41	std     %r3,96(%r1)	/*  argc */
42	std     %r4,104(%r1)	/*  argv */
43	std     %r5,112(%r1)	/*  envp */
44/*	std     %r6,120(%r1)   *//*  obj (always 0) */
45/*	std     %r7,128(%r1)   *//*  cleanup (always 0) */
46	std     %r8,136(%r1)	/*  ps_strings */
47
48	/*
49	 * Perform initial relocation of ld-elf.so. Not as easy as it
50	 * sounds.
51	 *  - perform small forward branch to put PC into link reg
52	 *  - use link-time constants to determine offset to the
53	 *    _DYNAMIC section and the GOT. Add these to the PC to
54	 *    convert to absolute addresses.
55	 *  - call reloc_non_plt_self() to fix up ld-elf.so's relocations
56	 */
57
58	bl	1f
59	.llong	_DYNAMIC-.
601:
61	mflr	%r3		/* PC value at .llong */
62	ld	%r4,0(%r3)	/* offset to _DYNAMIC */
63	add	%r3,%r4,%r3	/* r3 = &_DYNAMIC, absolute value */
64
65	ld	%r4,-0x8000(%r2) /* First TOC entry is TOC base */
66	subf	%r4,%r4,%r2	/* Subtract from real TOC base to get base */
67
68	bl	reloc_non_plt_self /* reloc_non_plt_self(&_DYNAMIC,base) */
69	nop
70
71	/*
72	 * The _rtld() function likes to see a stack layout containing
73	 * { argc, argv[0], argv[1] ... argv[N], 0, env[0], ... , env[N] }
74	 * Since the PowerPC stack was 16-byte aligned at exec time, the
75	 * original stack layout has to be found by moving back a word
76	 * from the argv pointer.
77	 */
78	ld	%r4,104(%r1)
79        addi    %r3,%r4,-8	/* locate argc ptr, &argv[-1] */
80	addi	%r4,%r1,128	/* &exit_proc on stack */
81	addi	%r5,%r1,120	/* &obj_main on stack */
82
83	bl      _rtld		/* &_start = _rtld(sp, &exit_proc, &obj_main)*/
84	nop
85#if !defined(_CALL_ELF) || _CALL_ELF == 1
86	ld	%r2,8(%r3)
87	ld	%r11,16(%r3)
88	ld	%r3,0(%r3)
89#else
90	mr	%r12,%r3
91#endif
92	mtlr    %r3
93
94	/*
95	 * Restore args, with new obj/exit proc
96	 */
97	ld      %r3,96(%r1)     /* argc */
98	ld      %r4,104(%r1)	/* argv */
99	ld      %r5,112(%r1)	/* envp */
100	ld      %r6,120(%r1)	/* obj */
101	ld      %r7,128(%r1)	/* exit proc */
102	ld      %r8,136(%r1)	/* ps_strings */
103
104	blrl	/* _start(argc, argv, envp, obj, cleanup, ps_strings) */
105
106	li      %r0,1		/* _exit() */
107	sc
108
109/*
110 * _rtld_bind_start()
111 *
112 * Call into the MI binder. This routine is reached via the PLT call cell
113 *
114 * On entry, %r11 contains an object pointer and %r0 contains the PLT index.
115 *
116 * Save all registers, call into the binder to resolve and fixup the external
117 * routine, and then transfer to the external routine on return.
118 */
119	.globl  _rtld_bind
120
121_ENTRY(_rtld_bind_start)
122	mr	%r12,%r0		# save r0 (index) immediately to r12
123	mflr    %r0
124	std     %r0,16(%r1)		# save lr
125	mfcr    %r0
126	std     %r0,8(%r1)		# save cr
127
128	stdu    %r1,-48-12*8(%r1)	# stack space for 8 regs + header
129					#   + 2 save regs
130	std	%r3,64+0*8(%r1)		# save r3-r10 (arguments)
131	std	%r4,64+1*8(%r1)
132	std	%r5,64+2*8(%r1)
133	std	%r6,64+3*8(%r1)
134	std	%r7,64+4*8(%r1)
135	std	%r8,64+5*8(%r1)
136	std	%r9,64+6*8(%r1)
137	std	%r10,64+7*8(%r1)
138
139	mr	%r3,%r11
140	mulli	%r4,%r12,24		# Multiply index by sizeof(Elf_Rela)
141
142	bl      _rtld_bind		# target addr = _rtld_bind(obj, reloff)
143	nop
144
145#if !defined(_CALL_ELF) || _CALL_ELF == 1
146	ld	%r2,8(%r3)
147	ld	%r11,16(%r3)
148	ld	%r3,0(%r3)
149#else
150	mr	%r12,%r3
151#endif
152	mtctr   %r3			# move absolute target addr into ctr
153
154	ld	%r3,64+0*8(%r1)		# restore r3-r10
155	ld	%r4,64+1*8(%r1)
156	ld	%r5,64+2*8(%r1)
157	ld	%r6,64+3*8(%r1)
158	ld	%r7,64+4*8(%r1)
159	ld	%r8,64+5*8(%r1)
160	ld	%r9,64+6*8(%r1)
161	ld	%r10,64+7*8(%r1)
162
163	ld	%r1,0(%r1)		# restore stack
164	ld	%r0,8(%r1)		# restore cr
165	mtcr    %r0
166	ld	%r0,16(%r1)		# restore lr
167	mtlr    %r0
168
169	bctr				# jump to target
170
171	.section .note.GNU-stack,"",%progbits
172