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
42	/* Save and restore only initial argv, because _rtld will modify
43	 * argv and envp if invoked explicitly, making it necessary to
44	 * load the (possibly) adjusted values from the stack.
45	 */
46	std     %r4,104(%r1)	/*  argv */
47/*	std     %r6,120(%r1)   *//*  obj (always 0) */
48/*	std     %r7,128(%r1)   *//*  cleanup (always 0) */
49	std     %r8,136(%r1)	/*  ps_strings */
50
51	/*
52	 * Perform initial relocation of ld-elf.so. Not as easy as it
53	 * sounds.
54	 *  - perform small forward branch to put PC into link reg
55	 *  - use link-time constants to determine offset to the
56	 *    _DYNAMIC section and the GOT. Add these to the PC to
57	 *    convert to absolute addresses.
58	 *  - call reloc_non_plt_self() to fix up ld-elf.so's relocations
59	 */
60
61	bl	1f
62	.llong	_DYNAMIC-.
631:
64	mflr	%r3		/* PC value at .llong */
65	ld	%r4,0(%r3)	/* offset to _DYNAMIC */
66	add	%r3,%r4,%r3	/* r3 = &_DYNAMIC, absolute value */
67
68	ld	%r4,-0x8000(%r2) /* First TOC entry is TOC base */
69	subf	%r4,%r4,%r2	/* Subtract from real TOC base to get base */
70
71	bl	reloc_non_plt_self /* reloc_non_plt_self(&_DYNAMIC,base) */
72	nop
73
74	/*
75	 * The _rtld() function likes to see a stack layout containing
76	 * { argc, argv[0], argv[1] ... argv[N], 0, env[0], ... , env[N] }
77	 * Since the PowerPC stack was 16-byte aligned at exec time, the
78	 * original stack layout has to be found by moving back a word
79	 * from the argv pointer.
80	 */
81	ld	%r4,104(%r1)
82        addi    %r3,%r4,-8	/* locate argc ptr, &argv[-1] */
83	addi	%r4,%r1,128	/* &exit_proc on stack */
84	addi	%r5,%r1,120	/* &obj_main on stack */
85
86	bl      _rtld		/* &_start = _rtld(sp, &exit_proc, &obj_main)*/
87	nop
88#if !defined(_CALL_ELF) || _CALL_ELF == 1
89	ld	%r2,8(%r3)
90	ld	%r11,16(%r3)
91	ld	%r3,0(%r3)
92#else
93	mr	%r12,%r3
94#endif
95	mtlr    %r3
96
97	/*
98	 * Restore args, with new obj/exit proc
99	 */
100	ld	%r4,104(%r1)	/* argv */
101	ld	%r3,-8(%r4)	/* argc */
102
103	/* envp = argv + argc + 1 */
104	addi	%r5,%r3,1
105	sldi	%r5,%r5,3	/* x8 */
106	add	%r5,%r4,%r5
107
108	ld      %r6,120(%r1)	/* obj */
109	ld      %r7,128(%r1)	/* exit proc */
110	ld      %r8,136(%r1)	/* ps_strings */
111
112	blrl	/* _start(argc, argv, envp, obj, cleanup, ps_strings) */
113
114	li      %r0,1		/* _exit() */
115	sc
116
117/*
118 * _rtld_bind_start()
119 *
120 * Call into the MI binder. This routine is reached via the PLT call cell
121 *
122 * On entry, %r11 contains an object pointer and %r0 contains the PLT index.
123 *
124 * Save all registers, call into the binder to resolve and fixup the external
125 * routine, and then transfer to the external routine on return.
126 */
127	.globl  _rtld_bind
128
129_ENTRY(_rtld_bind_start)
130	mr	%r12,%r0		# save r0 (index) immediately to r12
131	mflr    %r0
132	std     %r0,16(%r1)		# save lr
133	mfcr    %r0
134	std     %r0,8(%r1)		# save cr
135
136	stdu    %r1,-48-12*8(%r1)	# stack space for 8 regs + header
137					#   + 2 save regs
138	std	%r3,64+0*8(%r1)		# save r3-r10 (arguments)
139	std	%r4,64+1*8(%r1)
140	std	%r5,64+2*8(%r1)
141	std	%r6,64+3*8(%r1)
142	std	%r7,64+4*8(%r1)
143	std	%r8,64+5*8(%r1)
144	std	%r9,64+6*8(%r1)
145	std	%r10,64+7*8(%r1)
146
147	mr	%r3,%r11
148	mulli	%r4,%r12,24		# Multiply index by sizeof(Elf_Rela)
149
150	bl      _rtld_bind		# target addr = _rtld_bind(obj, reloff)
151	nop
152
153#if !defined(_CALL_ELF) || _CALL_ELF == 1
154	ld	%r2,8(%r3)
155	ld	%r11,16(%r3)
156	ld	%r3,0(%r3)
157#else
158	mr	%r12,%r3
159#endif
160	mtctr   %r3			# move absolute target addr into ctr
161
162	ld	%r3,64+0*8(%r1)		# restore r3-r10
163	ld	%r4,64+1*8(%r1)
164	ld	%r5,64+2*8(%r1)
165	ld	%r6,64+3*8(%r1)
166	ld	%r7,64+4*8(%r1)
167	ld	%r8,64+5*8(%r1)
168	ld	%r9,64+6*8(%r1)
169	ld	%r10,64+7*8(%r1)
170
171	ld	%r1,0(%r1)		# restore stack
172	ld	%r0,8(%r1)		# restore cr
173	mtcr    %r0
174	ld	%r0,16(%r1)		# restore lr
175	mtlr    %r0
176
177	bctr				# jump to target
178
179	.section .note.GNU-stack,"",%progbits
180