1/*-
2 * Copyright (c) 2014 The FreeBSD Foundation
3 * All rights reserved.
4 *
5 * This software was developed by Andrew Turner under
6 * sponsorship from the FreeBSD Foundation.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <machine/asm.h>
31__FBSDID("$FreeBSD$");
32
33ENTRY(.rtld_start)
34	mov	x19, x0		/* Put ps_strings in a callee-saved register */
35	mov	x20, sp		/* And the stack pointer */
36
37	/* Handle the old style stack */
38	/* TODO: Remove this when the kernel correctly aligns the stack */
39	cbnz	x0, 1f
40	mov	x0, sp		/* sp points to the args */
41	and	sp, x0, #~0xf	/* Align the stack as needed */
42
431:	sub	sp, sp, #16	/* Make room for obj_main & exit proc */
44
45	mov	x1, sp		/* exit_proc */
46	add	x2, x1, #8	/* obj_main */
47	bl	_rtld		/* Call the loader */
48	mov	x8, x0		/* Backup the entry point */
49
50	ldr	x2, [sp]	/* Load cleanup */
51	ldr	x1, [sp, #8]	/* Load obj_main */
52	mov	x0, x19		/* Restore ps_strings */
53	mov	sp, x20		/* Restore the stack pointer */
54	br	x8		/* Jump to the entry point */
55END(.rtld_start)
56
57/*
58 * sp + 0 = &GOT[x + 3]
59 * sp + 8 = RA
60 * x16 = &GOT[2]
61 * x17 = &_rtld_bind_start
62 */
63ENTRY(_rtld_bind_start)
64	mov	x17, sp
65
66	/* Save the arguments */
67	stp	x0, x1, [sp, #-16]!
68	stp	x2, x3, [sp, #-16]!
69	stp	x4, x5, [sp, #-16]!
70	stp	x6, x7, [sp, #-16]!
71
72	/* Calculate reloff */
73	ldr	x2, [x17, #0]	/* Get the address of the entry */
74	sub	x1, x2, x16	/* Find its offset */
75	sub	x1, x1, #8	/* Adjust for x16 not being at offset 0 */
76	/* Each rela item has 3 entriesso we need reloff = 3 * index */
77	lsl	x3, x1, #1	/* x3 = 2 * offset */
78	add	x1, x1, x3	/* x1 = x3 + offset = 3 * offset */
79
80	/* Load obj */
81	ldr	x0, [x16, #-8]
82
83	/* Call into rtld */
84	bl	_rtld_bind
85
86	/* Restore the registers saved by the plt code */
87	ldp	xzr, x30, [sp, #(4 * 16)]
88
89	/* Backup the address to branch to */
90	mov	x16, x0
91
92	/* restore the arguments */
93	ldp	x6, x7, [sp], #16
94	ldp	x4, x5, [sp], #16
95	ldp	x2, x3, [sp], #16
96	ldp	x0, x1, [sp], #16
97	/* And the part of the stack the plt entry handled */
98	add	sp, sp, #16
99
100	/* Call into the correct function */
101	br	x16
102END(_rtld_bind_start)
103
104/*
105 * uint64_t _rtld_tlsdesc(struct tlsdesc *);
106 *
107 * struct tlsdesc {
108 *  uint64_t ptr;
109 *  uint64_t data;
110 * };
111 *
112 * Returns the data.
113 */
114ENTRY(_rtld_tlsdesc)
115	ldr	x0, [x0, #8]
116	ret
117END(_rtld_tlsdesc)
118
119/*
120 * uint64_t _rtld_tlsdesc_dynamic(struct tlsdesc *);
121 *
122 * TODO: We could lookup the saved index here to skip saving the entire stack.
123 */
124ENTRY(_rtld_tlsdesc_dynamic)
125	/* Store any registers we may use in rtld_tlsdesc_handle */
126	stp	x29, x30, [sp, #-(10 * 16)]!
127	mov	x29, sp
128	stp	x1, x2,   [sp, #(1 * 16)]
129	stp	x3, x4,   [sp, #(2 * 16)]
130	stp	x5, x6,   [sp, #(3 * 16)]
131	stp	x7, x8,   [sp, #(4 * 16)]
132	stp	x9, x10,  [sp, #(5 * 16)]
133	stp	x11, x12, [sp, #(6 * 16)]
134	stp	x13, x14, [sp, #(7 * 16)]
135	stp	x15, x16, [sp, #(8 * 16)]
136	stp	x17, x18, [sp, #(9 * 16)]
137
138	/* Find the tls offset */
139	ldr	x0, [x0, #8]
140	mov	x1, #1
141	bl	rtld_tlsdesc_handle
142
143	/* Restore the registers */
144	ldp	x17, x18, [sp, #(9 * 16)]
145	ldp	x15, x16, [sp, #(8 * 16)]
146	ldp	x13, x14, [sp, #(7 * 16)]
147	ldp	x11, x12, [sp, #(6 * 16)]
148	ldp	x9, x10,  [sp, #(5 * 16)]
149	ldp	x7, x8,   [sp, #(4 * 16)]
150	ldp	x5, x6,   [sp, #(3 * 16)]
151	ldp	x3, x4,   [sp, #(2 * 16)]
152	ldp	x1, x2,   [sp, #(1 * 16)]
153	ldp	x29, x30, [sp], #(10 * 16)
154
155	ret
156END(_rtld_tlsdesc_dynamic)
157