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
|
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2013 Free Software Foundation, Inc.
*
* GRUB 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, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB 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 GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/offsets.h>
#include <grub/symbol.h>
#include <grub/machine/kernel.h>
/*
* uboot_syscall():
* This function is effectively a veneer, so it cannot
* modify the stack or corrupt any registers other than
* r12 (ip). Furthermore it needs to restore r8 for
* U-Boot (Global Data Pointer) and preserve it for Grub.
*/
FUNCTION(grub_uboot_syscall)
str r8, transition_space
str lr, transition_space + 4
str r9, transition_space + 8
ldr ip, saved_registers_ptr
ldr r8, [ip, #4 * 8]
ldr r9, [ip, #4 * 9]
bl do_syscall
ldr r8, transition_space
ldr lr, transition_space + 4
ldr r9, transition_space + 8
bx lr
do_syscall:
ldr ip, grub_uboot_syscall_ptr
bx ip
FUNCTION(grub_uboot_return)
ldr ip, saved_registers_ptr
ldr sp, [ip, #4 * 4]
pop {r4-r12, lr}
mov sp, r12
bx lr
.align 3
@ GRUB context stack space
transition_space:
.long 0 @ r8
.long 0 @ lr
.long 0 @ r9
saved_registers_ptr:
.long EXT_C(grub_arm_saved_registers)
VARIABLE(grub_uboot_syscall_ptr)
.long 0 @
END
|
