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
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
|
#------------------------------------------------------------------------------
#
# Use ARMv6 instruction to operate on a single stack
#
# Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
# Copyright (c) 2014, ARM Limited. All rights reserved.<BR>
#
# This program and the accompanying materials
# are licensed and made available under the terms and conditions of the BSD License
# which accompanies this distribution. The full text of the license may be found at
# http://opensource.org/licenses/bsd-license.php
#
# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
#
#------------------------------------------------------------------------------
#include <Library/PcdLib.h>
/*
This is the stack constructed by the exception handler (low address to high address)
# R0 - IFAR is EFI_SYSTEM_CONTEXT for ARM
Reg Offset
=== ======
R0 0x00 # stmfd SP!,{R0-R12}
R1 0x04
R2 0x08
R3 0x0c
R4 0x10
R5 0x14
R6 0x18
R7 0x1c
R8 0x20
R9 0x24
R10 0x28
R11 0x2c
R12 0x30
SP 0x34 # reserved via subtraction 0x20 (32) from SP
LR 0x38
PC 0x3c
CPSR 0x40
DFSR 0x44
DFAR 0x48
IFSR 0x4c
IFAR 0x50
LR 0x54 # SVC Link register (we need to restore it)
LR 0x58 # pushed by srsfd
CPSR 0x5c
*/
GCC_ASM_EXPORT(ExceptionHandlersStart)
GCC_ASM_EXPORT(ExceptionHandlersEnd)
GCC_ASM_EXPORT(CommonExceptionEntry)
GCC_ASM_EXPORT(AsmCommonExceptionEntry)
GCC_ASM_EXPORT(CommonCExceptionHandler)
.text
#if !defined(__APPLE__)
.fpu neon @ makes vpush/vpop assemble
#endif
.align 5
//
// This code gets copied to the ARM vector table
// ExceptionHandlersStart - ExceptionHandlersEnd gets copied
//
ASM_PFX(ExceptionHandlersStart):
ASM_PFX(Reset):
b ASM_PFX(ResetEntry)
ASM_PFX(UndefinedInstruction):
b ASM_PFX(UndefinedInstructionEntry)
ASM_PFX(SoftwareInterrupt):
b ASM_PFX(SoftwareInterruptEntry)
ASM_PFX(PrefetchAbort):
b ASM_PFX(PrefetchAbortEntry)
ASM_PFX(DataAbort):
b ASM_PFX(DataAbortEntry)
ASM_PFX(ReservedException):
b ASM_PFX(ReservedExceptionEntry)
ASM_PFX(Irq):
b ASM_PFX(IrqEntry)
ASM_PFX(Fiq):
b ASM_PFX(FiqEntry)
ASM_PFX(ResetEntry):
srsdb #0x13! @ Store return state on SVC stack
@ We are already in SVC mode
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov R0,#0 @ ExceptionType
ldr R1,ASM_PFX(CommonExceptionEntry)
bx R1
ASM_PFX(UndefinedInstructionEntry):
sub LR, LR, #4 @ Only -2 for Thumb, adjust in CommonExceptionEntry
srsdb #0x13! @ Store return state on SVC stack
cps #0x13 @ Switch to SVC for common stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov R0,#1 @ ExceptionType
ldr R1,ASM_PFX(CommonExceptionEntry)
bx R1
ASM_PFX(SoftwareInterruptEntry):
srsdb #0x13! @ Store return state on SVC stack
@ We are already in SVC mode
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov R0,#2 @ ExceptionType
ldr R1,ASM_PFX(CommonExceptionEntry)
bx R1
ASM_PFX(PrefetchAbortEntry):
sub LR,LR,#4
srsdb #0x13! @ Store return state on SVC stack
cps #0x13 @ Switch to SVC for common stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov R0,#3 @ ExceptionType
ldr R1,ASM_PFX(CommonExceptionEntry)
bx R1
ASM_PFX(DataAbortEntry):
sub LR,LR,#8
srsdb #0x13! @ Store return state on SVC stack
cps #0x13 @ Switch to SVC for common stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov R0,#4
ldr R1,ASM_PFX(CommonExceptionEntry)
bx R1
ASM_PFX(ReservedExceptionEntry):
srsdb #0x13! @ Store return state on SVC stack
cps #0x13 @ Switch to SVC for common stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov R0,#5
ldr R1,ASM_PFX(CommonExceptionEntry)
bx R1
ASM_PFX(IrqEntry):
sub LR,LR,#4
srsdb #0x13! @ Store return state on SVC stack
cps #0x13 @ Switch to SVC for common stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov R0,#6 @ ExceptionType
ldr R1,ASM_PFX(CommonExceptionEntry)
bx R1
ASM_PFX(FiqEntry):
sub LR,LR,#4
srsdb #0x13! @ Store return state on SVC stack
cps #0x13 @ Switch to SVC for common stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
@ Since we have already switch to SVC R8_fiq - R12_fiq
@ never get used or saved
mov R0,#7 @ ExceptionType
ldr R1,ASM_PFX(CommonExceptionEntry)
bx R1
//
// This gets patched by the C code that patches in the vector table
//
ASM_PFX(CommonExceptionEntry):
.word ASM_PFX(AsmCommonExceptionEntry)
ASM_PFX(ExceptionHandlersEnd):
//
// This code runs from CpuDxe driver loaded address. It is patched into
// CommonExceptionEntry.
//
ASM_PFX(AsmCommonExceptionEntry):
mrc p15, 0, R1, c6, c0, 2 @ Read IFAR
str R1, [SP, #0x50] @ Store it in EFI_SYSTEM_CONTEXT_ARM.IFAR
mrc p15, 0, R1, c5, c0, 1 @ Read IFSR
str R1, [SP, #0x4c] @ Store it in EFI_SYSTEM_CONTEXT_ARM.IFSR
mrc p15, 0, R1, c6, c0, 0 @ Read DFAR
str R1, [SP, #0x48] @ Store it in EFI_SYSTEM_CONTEXT_ARM.DFAR
mrc p15, 0, R1, c5, c0, 0 @ Read DFSR
str R1, [SP, #0x44] @ Store it in EFI_SYSTEM_CONTEXT_ARM.DFSR
ldr R1, [SP, #0x5c] @ srsdb saved pre-exception CPSR on the stack
str R1, [SP, #0x40] @ Store it in EFI_SYSTEM_CONTEXT_ARM.CPSR
add R2, SP, #0x38 @ Make R2 point to EFI_SYSTEM_CONTEXT_ARM.LR
and R3, R1, #0x1f @ Check CPSR to see if User or System Mode
cmp R3, #0x1f @ if ((CPSR == 0x10) || (CPSR == 0x1f))
cmpne R3, #0x10 @
stmeqed R2, {lr}^ @ save unbanked lr
@ else
stmneed R2, {lr} @ save SVC lr
ldr R5, [SP, #0x58] @ PC is the LR pushed by srsfd
@ Check to see if we have to adjust for Thumb entry
sub r4, r0, #1 @ if (ExceptionType == 1 || ExceptionType == 2)) {
cmp r4, #1 @ // UND & SVC have differnt LR adjust for Thumb
bhi NoAdjustNeeded
tst r1, #0x20 @ if ((CPSR & T)) == T) { // Thumb Mode on entry
addne R5, R5, #2 @ PC += 2;
strne R5,[SP,#0x58] @ Update LR value pushed by srsfd
NoAdjustNeeded:
str R5, [SP, #0x3c] @ Store it in EFI_SYSTEM_CONTEXT_ARM.PC
add R1, SP, #0x60 @ We pushed 0x60 bytes on the stack
str R1, [SP, #0x34] @ Store it in EFI_SYSTEM_CONTEXT_ARM.SP
@ R0 is ExceptionType
mov R1,SP @ R1 is SystemContext
#if (FixedPcdGet32(PcdVFPEnabled))
vpush {d0-d15} @ save vstm registers in case they are used in optimizations
#endif
mov R4, SP @ Save current SP
tst R4, #4
subne SP, SP, #4 @ Adjust SP if not 8-byte aligned
/*
VOID
EFIAPI
CommonCExceptionHandler (
IN EFI_EXCEPTION_TYPE ExceptionType, R0
IN OUT EFI_SYSTEM_CONTEXT SystemContext R1
)
*/
blx ASM_PFX(CommonCExceptionHandler) @ Call exception handler
mov SP, R4 @ Restore SP
#if (FixedPcdGet32(PcdVFPEnabled))
vpop {d0-d15}
#endif
ldr R1, [SP, #0x4c] @ Restore EFI_SYSTEM_CONTEXT_ARM.IFSR
mcr p15, 0, R1, c5, c0, 1 @ Write IFSR
ldr R1, [SP, #0x44] @ Restore EFI_SYSTEM_CONTEXT_ARM.DFSR
mcr p15, 0, R1, c5, c0, 0 @ Write DFSR
ldr R1,[SP,#0x3c] @ EFI_SYSTEM_CONTEXT_ARM.PC
str R1,[SP,#0x58] @ Store it back to srsfd stack slot so it can be restored
ldr R1,[SP,#0x40] @ EFI_SYSTEM_CONTEXT_ARM.CPSR
str R1,[SP,#0x5c] @ Store it back to srsfd stack slot so it can be restored
add R3, SP, #0x54 @ Make R3 point to SVC LR saved on entry
add R2, SP, #0x38 @ Make R2 point to EFI_SYSTEM_CONTEXT_ARM.LR
and R1, R1, #0x1f @ Check to see if User or System Mode
cmp R1, #0x1f @ if ((CPSR == 0x10) || (CPSR == 0x1f))
cmpne R1, #0x10 @
ldmeqed R2, {lr}^ @ restore unbanked lr
@ else
ldmneed R3, {lr} @ restore SVC lr, via ldmfd SP!, {LR}
ldmfd SP!,{R0-R12} @ Restore general purpose registers
@ Exception handler can not change SP
add SP,SP,#0x20 @ Clear out the remaining stack space
ldmfd SP!,{LR} @ restore the link register for this context
rfefd SP! @ return from exception via srsfd stack slot
|
