1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
|
/*
* This file is part of the libpayload project.
*
* Copyright (C) 2014 Imagination Technologies
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc.
*/
#include <arch/cpu.h>
/* Disable interrupts and mark the kernel mode */
.macro setup_c0_status clr
.set push
mfc0 $t0, $CP0_STATUS
or $t0, ST0_CU0 | 0x1f | \clr
xor $t0, 0x1f | \clr
mtc0 $t0, $CP0_STATUS
.set noreorder
sll $zero, 3
.set pop
.endm
/* Don't reorder instructions */
.set noreorder
.align 4
.global cb_header_ptr
cb_header_ptr:
.word 0
.global old_sp
old_sp:
.word 0
.global _entry, _leave
.text
/* Our entry point */
_entry:
/*
* This function saves off the previous stack and switches us to our
* own execution environment.
*/
/* Clear watch and cause registers */
mtc0 $zero, $CP0_WATCHLO
mtc0 $zero, $CP0_WATCHHI
mtc0 $zero, $CP0_CAUSE
/* Disable interrupts */
setup_c0_status 0
/* Don't use at in synthetic instr. */
.set noat
/* Init timer */
mtc0 $zero, $CP0_COUNT
mtc0 $zero, $CP0_COMPARE
/* Initialize $gp */
bal 1f
nop
.word _gp
1:
lw $gp, 0($ra)
/* Clear .bss: start_bss = _edata, end_bss = _end */
la $t0, _edata
sw $zero, ($t0)
la $t1, _end - 4
clear_bss:
addiu $t0, 4
sw $zero, ($t0)
bne $t0, $t1, clear_bss
nop
/* Save off the location of the coreboot tables */
la $at, cb_header_ptr
sw $a0, 0x00($at)
/* Save old stack pointer */
la $at, old_sp
sw $sp, 0x00($at)
/* Setup new stack */
la $sp, _stack
/* Let's rock */
la $a2, start_main
jalr $a2
nop
_leave:
/* Restore old stack. */
lw $sp, old_sp
/* Return to the original context. */
eret
|
