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
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
/*
* This file is part of the coreboot project.
*
* Copyright 2014 Google Inc.
*
* 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.
*/
/*
* transition_asm.S: This file handles the entry and exit from an exception
*
* Flow: exception --> exc_vectors --> exc_entry --> exc_dispatch -->
* exc_exit
* Transition Flow: transition --> trans_switch --> exc_exit
*
* |---| Exception Entry |---|
*
* On exception entry, it saves all the xregs on SP_ELx since SP_ELx is
* selected on entry. Some dummy pushes are performed to create space for
* elx_state structure. It then passes pointer to this saved set of regs and
* a unique id(for identifying exception) to exc_entry.
*
* |---| Exception Transition Dispatch |---|
*
* This is the C-component of exception entry. It does the work of initializing
* the exc_state registers. Finally it calls exception dispatch implemented by
* the user. This is point of no-return.
*
* |---| Exception Dispatch |---|
*
* User of this functionality is expected to implement exc_dispatch which
* acts as entry point for it. Once exception handling is complete, the user
* needs to call exc_exit with pointer to struct regs.
*
* |---| Exception Exit |---|
*
* Once exc_dispatch is done with handling the exception based on the id passed
* to it, it needs to call exc_exit with pointer to struct regs. This is done to
* unwind the exception stack by popping off all the xregs.
*
* |---| Exception Transition Exit |---|
*
* This routine makes SP_EL0 point to the regs structure passed and continues
* onto the exception exit routine described above. This is the reason that
* transition library does not handle initialization of SP_EL0 for the program
* to be executed.
*/
#include <arch/asm.h>
#include <arch/lib_helpers.h>
#include <arch/transition.h>
.macro eentry lbl id
.align 7
\lbl:
stp x29, x30, [sp, #STACK_PUSH_BYTES]!
bl exc_prologue
mov x1, \id
mov x0, sp
b exc_entry
.endm
/*
* exc_vectors: Entry point for an exception
*/
ENTRY_WITH_ALIGN(exc_vectors, 11)
eentry sync_curr_sp0, #EXC_VID_CUR_SP_EL0_SYNC
eentry irq_curr_sp0, #EXC_VID_CUR_SP_EL0_IRQ
eentry fiq_curr_sp0, #EXC_VID_CUR_SP_EL0_FIRQ
eentry serror_curr_sp0, #EXC_VID_CUR_SP_EL0_SERR
eentry sync_curr_spx, #EXC_VID_CUR_SP_ELX_SYNC
eentry irq_curr_spx, #EXC_VID_CUR_SP_ELX_IRQ
eentry fiq_curr_spx, #EXC_VID_CUR_SP_ELX_FIQ
eentry serror_curr_spx, #EXC_VID_CUR_SP_ELX_SERR
eentry sync_lower_64, #EXC_VID_LOW64_SYNC
eentry irq_lower_64, #EXC_VID_LOW64_IRQ
eentry fiq_lower_64, #EXC_VID_LOW64_FIQ
eentry serror_lower_64, #EXC_VID_LOW64_SERR
eentry sync_lower_32, #EXC_VID_LOW32_SYNC
eentry irq_lower_32, #EXC_VID_LOW32_IRQ
eentry fiq_lower_32, #EXC_VID_LOW32_FIQ
eentry serror_lower_32, #EXC_VID_LOW32_SERR
ENDPROC(exc_vectors)
ENTRY(exc_prologue)
stp x27, x28, [sp, #STACK_PUSH_BYTES]!
stp x25, x26, [sp, #STACK_PUSH_BYTES]!
stp x23, x24, [sp, #STACK_PUSH_BYTES]!
stp x21, x22, [sp, #STACK_PUSH_BYTES]!
stp x19, x20, [sp, #STACK_PUSH_BYTES]!
stp x17, x18, [sp, #STACK_PUSH_BYTES]!
stp x15, x16, [sp, #STACK_PUSH_BYTES]!
stp x13, x14, [sp, #STACK_PUSH_BYTES]!
stp x11, x12, [sp, #STACK_PUSH_BYTES]!
stp x9, x10, [sp, #STACK_PUSH_BYTES]!
stp x7, x8, [sp, #STACK_PUSH_BYTES]!
stp x5, x6, [sp, #STACK_PUSH_BYTES]!
stp x3, x4, [sp, #STACK_PUSH_BYTES]!
stp x1, x2, [sp, #STACK_PUSH_BYTES]!
/* xzr pushed as place holder for sp */
stp xzr, x0, [sp, #STACK_PUSH_BYTES]!
/*
* xzr pushed as place holder for:
* 1. sp_elx and elr
*/
stp xzr, xzr, [sp, #STACK_PUSH_BYTES]!
/* 2. spsr and sp_el0 */
stp xzr, xzr, [sp, #STACK_PUSH_BYTES]!
ret
ENDPROC(exc_prologue)
/*
* trans_switch: Set SPSel to use SP_EL0
* x0 = regs structure
*/
ENTRY(trans_switch)
msr SPSel, #SPSR_USE_L
b exc_exit
ENDPROC(trans_switch)
/*
* exc_exit: Return from exception by restoring saved state of xregs
* x0 = regs structure
*/
ENTRY(exc_exit)
/* Unwind the stack by making sp point to regs structure */
mov sp, x0
/* Load registers x0-x30 */
ldp xzr, x0, [sp], #STACK_POP_BYTES
ldp x1, x2, [sp], #STACK_POP_BYTES
ldp x3, x4, [sp], #STACK_POP_BYTES
ldp x5, x6, [sp], #STACK_POP_BYTES
ldp x7, x8, [sp], #STACK_POP_BYTES
ldp x9, x10, [sp], #STACK_POP_BYTES
ldp x11, x12, [sp], #STACK_POP_BYTES
ldp x13, x14, [sp], #STACK_POP_BYTES
ldp x15, x16, [sp], #STACK_POP_BYTES
ldp x17, x18, [sp], #STACK_POP_BYTES
ldp x19, x20, [sp], #STACK_POP_BYTES
ldp x21, x22, [sp], #STACK_POP_BYTES
ldp x23, x24, [sp], #STACK_POP_BYTES
ldp x25, x26, [sp], #STACK_POP_BYTES
ldp x27, x28, [sp], #STACK_POP_BYTES
ldp x29, x30, [sp], #STACK_POP_BYTES
eret
ENDPROC(exc_exit)
/*
* exception_init_asm: Initialize VBAR and point SP_EL3 to exception stack.
* x0 = end of exception stack
*/
ENTRY(exception_init_asm)
msr SPSel, #SPSR_USE_H
mov sp, x0
msr SPSel, #SPSR_USE_L
adr x0, exc_vectors
msr vbar_el3, x0
dsb sy
isb
ret
ENDPROC(exception_init_asm)
|
