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98bc0c8c | 1 | #------------------------------------------------------------------------------ |
2 | # | |
3 | # Use ARMv6 instruction to operate on a single stack | |
4 | # | |
5 | # Copyright (c) 2008-2010 Apple Inc. All rights reserved. | |
6 | # | |
7 | # All rights reserved. This program and the accompanying materials | |
8 | # are licensed and made available under the terms and conditions of the BSD License | |
9 | # which accompanies this distribution. The full text of the license may be found at | |
10 | # http://opensource.org/licenses/bsd-license.php | |
11 | # | |
12 | # THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, | |
13 | # WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. | |
14 | # | |
15 | #------------------------------------------------------------------------------ | |
16 | ||
17 | /* | |
18 | ||
19 | This is the stack constructed by the exception handler (low address to high address) | |
20 | # R0 - IFAR is EFI_SYSTEM_CONTEXT for ARM | |
21 | Reg Offset | |
22 | === ====== | |
23 | R0 0x00 # stmfd SP!,{R0-R12} | |
24 | R1 0x04 | |
25 | R2 0x08 | |
26 | R3 0x0c | |
27 | R4 0x10 | |
28 | R5 0x14 | |
29 | R6 0x18 | |
30 | R7 0x1c | |
31 | R8 0x20 | |
32 | R9 0x24 | |
33 | R10 0x28 | |
34 | R11 0x2c | |
35 | R12 0x30 | |
36 | SP 0x34 # reserved via adding 0x20 (32) to the SP | |
37 | LR 0x38 | |
38 | PC 0x3c | |
39 | CPSR 0x40 | |
40 | DFSR 0x44 | |
41 | DFAR 0x48 | |
42 | IFSR 0x4c | |
43 | IFAR 0x50 | |
44 | ||
45 | LR 0x54 # SVC Link register (we need to restore it) | |
46 | ||
47 | LR 0x58 # pushed by srsfd | |
48 | CPSR 0x5c | |
49 | ||
50 | */ | |
51 | ||
52 | ||
53 | .globl ASM_PFX(ExceptionHandlersStart) | |
54 | .globl ASM_PFX(ExceptionHandlersEnd) | |
55 | .globl ASM_PFX(CommonExceptionEntry) | |
56 | .globl ASM_PFX(AsmCommonExceptionEntry) | |
57 | .globl ASM_PFX(CommonCExceptionHandler) | |
58 | ||
59 | .text | |
60 | .align 3 | |
61 | ||
62 | ||
63 | // | |
64 | // This code gets copied to the ARM vector table | |
65 | // ExceptionHandlersStart - ExceptionHandlersEnd gets copied | |
66 | // | |
67 | ASM_PFX(ExceptionHandlersStart): | |
68 | ||
69 | ASM_PFX(Reset): | |
70 | b ASM_PFX(ResetEntry) | |
71 | ||
72 | ASM_PFX(UndefinedInstruction): | |
73 | b ASM_PFX(UndefinedInstructionEntry) | |
74 | ||
75 | ASM_PFX(SoftwareInterrupt): | |
76 | b ASM_PFX(SoftwareInterruptEntry) | |
77 | ||
78 | ASM_PFX(PrefetchAbort): | |
79 | b ASM_PFX(PrefetchAbortEntry) | |
80 | ||
81 | ASM_PFX(DataAbort): | |
82 | b ASM_PFX(DataAbortEntry) | |
83 | ||
84 | ASM_PFX(ReservedException): | |
85 | b ASM_PFX(ReservedExceptionEntry) | |
86 | ||
87 | ASM_PFX(Irq): | |
88 | b ASM_PFX(IrqEntry) | |
89 | ||
90 | ASM_PFX(Fiq): | |
91 | b ASM_PFX(FiqEntry) | |
92 | ||
93 | ASM_PFX(ResetEntry): | |
94 | srsdb #0x13! @ Store return state on SVC stack | |
95 | @ We are already in SVC mode | |
96 | ||
97 | stmfd SP!,{LR} @ Store the link register for the current mode | |
98 | sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR | |
99 | stmfd SP!,{R0-R12} @ Store the register state | |
100 | ||
101 | mov R0,#0 @ ExceptionType | |
102 | ldr R1,ASM_PFX(CommonExceptionEntry) | |
103 | bx R1 | |
104 | ||
105 | ASM_PFX(UndefinedInstructionEntry): | |
106 | sub LR, LR, #4 @ Only -2 for Thumb, adjust in CommonExceptionEntry | |
107 | srsdb #0x13! @ Store return state on SVC stack | |
108 | cps #0x13 @ Switch to SVC for common stack | |
109 | stmfd SP!,{LR} @ Store the link register for the current mode | |
110 | sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR | |
111 | stmfd SP!,{R0-R12} @ Store the register state | |
112 | ||
113 | mov R0,#1 @ ExceptionType | |
114 | ldr R1,ASM_PFX(CommonExceptionEntry) | |
115 | bx R1 | |
116 | ||
117 | ASM_PFX(SoftwareInterruptEntry): | |
118 | sub LR, LR, #4 @ Only -2 for Thumb, adjust in CommonExceptionEntry | |
119 | srsdb #0x13! @ Store return state on SVC stack | |
120 | @ We are already in SVC mode | |
121 | stmfd SP!,{LR} @ Store the link register for the current mode | |
122 | sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR | |
123 | stmfd SP!,{R0-R12} @ Store the register state | |
124 | ||
125 | mov R0,#2 @ ExceptionType | |
126 | ldr R1,ASM_PFX(CommonExceptionEntry) | |
127 | bx R1 | |
128 | ||
129 | ASM_PFX(PrefetchAbortEntry): | |
130 | sub LR,LR,#4 | |
131 | srsdb #0x13! @ Store return state on SVC stack | |
132 | cps #0x13 @ Switch to SVC for common stack | |
133 | stmfd SP!,{LR} @ Store the link register for the current mode | |
134 | sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR | |
135 | stmfd SP!,{R0-R12} @ Store the register state | |
136 | ||
137 | mov R0,#3 @ ExceptionType | |
138 | ldr R1,ASM_PFX(CommonExceptionEntry) | |
139 | bx R1 | |
140 | ||
141 | ASM_PFX(DataAbortEntry): | |
142 | sub LR,LR,#8 | |
143 | srsdb #0x13! @ Store return state on SVC stack | |
144 | cps #0x13 @ Switch to SVC for common stack | |
145 | stmfd SP!,{LR} @ Store the link register for the current mode | |
146 | sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR | |
147 | stmfd SP!,{R0-R12} @ Store the register state | |
148 | ||
149 | mov R0,#4 | |
150 | ldr R1,ASM_PFX(CommonExceptionEntry) | |
151 | bx R1 | |
152 | ||
153 | ASM_PFX(ReservedExceptionEntry): | |
154 | srsdb #0x13! @ Store return state on SVC stack | |
155 | cps #0x13 @ Switch to SVC for common stack | |
156 | stmfd SP!,{LR} @ Store the link register for the current mode | |
157 | sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR | |
158 | stmfd SP!,{R0-R12} @ Store the register state | |
159 | ||
160 | mov R0,#5 | |
161 | ldr R1,ASM_PFX(CommonExceptionEntry) | |
162 | bx R1 | |
163 | ||
164 | ASM_PFX(IrqEntry): | |
165 | sub LR,LR,#4 | |
166 | srsdb #0x13! @ Store return state on SVC stack | |
167 | cps #0x13 @ Switch to SVC for common stack | |
168 | stmfd SP!,{LR} @ Store the link register for the current mode | |
169 | sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR | |
170 | stmfd SP!,{R0-R12} @ Store the register state | |
171 | ||
172 | mov R0,#6 @ ExceptionType | |
173 | ldr R1,ASM_PFX(CommonExceptionEntry) | |
174 | bx R1 | |
175 | ||
176 | ASM_PFX(FiqEntry): | |
177 | sub LR,LR,#4 | |
178 | srsdb #0x13! @ Store return state on SVC stack | |
179 | cps #0x13 @ Switch to SVC for common stack | |
180 | stmfd SP!,{LR} @ Store the link register for the current mode | |
181 | sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR | |
182 | stmfd SP!,{R0-R12} @ Store the register state | |
183 | @ Since we have already switch to SVC R8_fiq - R12_fiq | |
184 | @ never get used or saved | |
185 | mov R0,#7 @ ExceptionType | |
186 | ldr R1,ASM_PFX(CommonExceptionEntry) | |
187 | bx R1 | |
188 | ||
189 | // | |
190 | // This gets patched by the C code that patches in the vector table | |
191 | // | |
192 | ASM_PFX(CommonExceptionEntry): | |
193 | .byte 0x12 | |
194 | .byte 0x34 | |
195 | .byte 0x56 | |
196 | .byte 0x78 | |
197 | ||
198 | ASM_PFX(ExceptionHandlersEnd): | |
199 | ||
200 | // | |
201 | // This code runs from CpuDxe driver loaded address. It is patched into | |
202 | // CommonExceptionEntry. | |
203 | // | |
204 | ASM_PFX(AsmCommonExceptionEntry): | |
205 | mrc p15, 0, R1, c6, c0, 2 @ Read IFAR | |
206 | str R1, [SP, #0x50] @ Store it in EFI_SYSTEM_CONTEXT_ARM.IFAR | |
207 | ||
208 | mrc p15, 0, R1, c5, c0, 1 @ Read IFSR | |
209 | str R1, [SP, #0x4c] @ Store it in EFI_SYSTEM_CONTEXT_ARM.IFSR | |
210 | ||
211 | mrc p15, 0, R1, c6, c0, 0 @ Read DFAR | |
212 | str R1, [SP, #0x48] @ Store it in EFI_SYSTEM_CONTEXT_ARM.DFAR | |
213 | ||
214 | mrc p15, 0, R1, c5, c0, 0 @ Read DFSR | |
215 | str R1, [SP, #0x44] @ Store it in EFI_SYSTEM_CONTEXT_ARM.DFSR | |
216 | ||
217 | ldr R1, [SP, #0x5c] @ srsdb saved pre-exception CPSR on the stack | |
218 | str R1, [SP, #0x40] @ Store it in EFI_SYSTEM_CONTEXT_ARM.CPSR | |
219 | ||
220 | add R2, SP, #0x38 @ Make R2 point to EFI_SYSTEM_CONTEXT_ARM.LR | |
221 | and R3, R1, #0x1f @ Check CPSR to see if User or System Mode | |
222 | cmp R3, #0x1f @ if ((CPSR == 0x10) || (CPSR == 0x1df)) | |
223 | cmpne R3, #0x10 @ | |
224 | stmeqed R2, {lr}^ @ save unbanked lr | |
225 | @ else | |
226 | stmneed R2, {lr} @ save SVC lr | |
227 | ||
228 | ||
229 | ldr R5, [SP, #0x58] @ PC is the LR pushed by srsfd | |
230 | @ Check to see if we have to adjust for Thumb entry | |
231 | sub r4, r0, #1 @ if (ExceptionType == 1 || ExceptionType ==2)) { | |
232 | cmp r4, #1 @ // UND & SVC have differnt LR adjust for Thumb | |
233 | bhi NoAdjustNeeded | |
234 | ||
235 | tst r1, #0x20 @ if ((CPSR & T)) == T) { // Thumb Mode on entry | |
236 | addne R5, R5, #2 @ PC += 2@ | |
237 | str R5,[SP,#0x58] @ Update LR value pused by srsfd | |
238 | ||
239 | NoAdjustNeeded: | |
240 | ||
241 | str R5, [SP, #0x3c] @ Store it in EFI_SYSTEM_CONTEXT_ARM.PC | |
242 | ||
243 | sub R1, SP, #0x60 @ We pused 0x60 bytes on the stack | |
244 | str R1, [SP, #0x34] @ Store it in EFI_SYSTEM_CONTEXT_ARM.SP | |
245 | ||
246 | @ R0 is ExceptionType | |
247 | mov R1,SP @ R1 is SystemContext | |
248 | ||
249 | /* | |
250 | VOID | |
251 | EFIAPI | |
252 | CommonCExceptionHandler ( | |
253 | IN EFI_EXCEPTION_TYPE ExceptionType, R0 | |
254 | IN OUT EFI_SYSTEM_CONTEXT SystemContext R1 | |
255 | ) | |
256 | ||
257 | */ | |
258 | blx ASM_PFX(CommonCExceptionHandler) @ Call exception handler | |
bb02cb80 | 259 | |
260 | ldr R1, [SP, #0x4c] @ Restore EFI_SYSTEM_CONTEXT_ARM.IFSR | |
261 | mcr p15, 0, R1, c5, c0, 1 @ Write IFSR | |
262 | ||
263 | ldr R1, [SP, #0x44] @ sRestore EFI_SYSTEM_CONTEXT_ARM.DFSR | |
264 | mcr p15, 0, R1, c5, c0, 0 @ Write DFSR | |
98bc0c8c | 265 | |
266 | ldr R1,[SP,#0x3c] @ EFI_SYSTEM_CONTEXT_ARM.PC | |
267 | str R1,[SP,#0x58] @ Store it back to srsfd stack slot so it can be restored | |
268 | ||
269 | ldr R1,[SP,#0x40] @ EFI_SYSTEM_CONTEXT_ARM.CPSR | |
270 | str R1,[SP,#0x5c] @ Store it back to srsfd stack slot so it can be restored | |
271 | ||
272 | add R3, SP, #0x54 @ Make R3 point to SVC LR saved on entry | |
273 | add R2, SP, #0x38 @ Make R2 point to EFI_SYSTEM_CONTEXT_ARM.LR | |
274 | and R1, R1, #0x1f @ Check to see if User or System Mode | |
275 | cmp R1, #0x1f @ if ((CPSR == 0x10) || (CPSR == 0x1f)) | |
276 | cmpne R1, #0x10 @ | |
277 | ldmeqed R2, {lr}^ @ restore unbanked lr | |
278 | @ else | |
279 | ldmneed R3, {lr} @ restore SVC lr, via ldmfd SP!, {LR} | |
280 | ||
281 | ldmfd SP!,{R0-R12} @ Restore general purpose registers | |
282 | @ Exception handler can not change SP | |
283 | ||
284 | add SP,SP,#0x20 @ Clear out the remaining stack space | |
285 | ldmfd SP!,{LR} @ restore the link register for this context | |
286 | rfefd SP! @ return from exception via srsfd stack slot | |
287 |