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
/*
* Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <assert_macros.S>
#include <asm_macros.S>
#include <assert_macros.S>
#include <bl31/ea_handle.h>
#include <context.h>
#include <lib/extensions/ras_arch.h>
.globl handle_lower_el_ea_esb
.globl enter_lower_el_sync_ea
.globl enter_lower_el_async_ea
/*
* Function to delegate External Aborts synchronized by ESB instruction at EL3
* vector entry. This function assumes GP registers x0-x29 have been saved, and
* are available for use. It delegates the handling of the EA to platform
* handler, and returns only upon successfully handling the EA; otherwise
* panics. On return from this function, the original exception handler is
* expected to resume.
*/
func handle_lower_el_ea_esb
mov x0, #ERROR_EA_ESB
mrs x1, DISR_EL1
b ea_proceed
endfunc handle_lower_el_ea_esb
/*
* This function forms the tail end of Synchronous Exception entry from lower
* EL, and expects to handle only Synchronous External Aborts from lower EL. If
* any other kind of exception is detected, then this function reports unhandled
* exception.
*
* Since it's part of exception vector, this function doesn't expect any GP
* registers to have been saved. It delegates the handling of the EA to platform
* handler, and upon successfully handling the EA, exits EL3; otherwise panics.
*/
func enter_lower_el_sync_ea
/*
* Explicitly save x30 so as to free up a register and to enable
* branching.
*/
str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
mrs x30, esr_el3
ubfx x30, x30, #ESR_EC_SHIFT, #ESR_EC_LENGTH
/* Check for I/D aborts from lower EL */
cmp x30, #EC_IABORT_LOWER_EL
b.eq 1f
cmp x30, #EC_DABORT_LOWER_EL
b.ne 2f
1:
/* Test for EA bit in the instruction syndrome */
mrs x30, esr_el3
tbz x30, #ESR_ISS_EABORT_EA_BIT, 2f
/* Save GP registers */
bl save_gp_registers
/* Save ARMv8.3-PAuth registers and load firmware key */
#if CTX_INCLUDE_PAUTH_REGS
bl pauth_context_save
#endif
#if ENABLE_PAUTH
bl pauth_load_bl_apiakey
#endif
/* Setup exception class and syndrome arguments for platform handler */
mov x0, #ERROR_EA_SYNC
mrs x1, esr_el3
adr x30, el3_exit
b delegate_sync_ea
2:
/* Synchronous exceptions other than the above are assumed to be EA */
ldr x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
no_ret report_unhandled_exception
endfunc enter_lower_el_sync_ea
/*
* This function handles SErrors from lower ELs.
*
* Since it's part of exception vector, this function doesn't expect any GP
* registers to have been saved. It delegates the handling of the EA to platform
* handler, and upon successfully handling the EA, exits EL3; otherwise panics.
*/
func enter_lower_el_async_ea
/*
* Explicitly save x30 so as to free up a register and to enable
* branching
*/
str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
/* Save GP registers */
bl save_gp_registers
/* Save ARMv8.3-PAuth registers and load firmware key */
#if CTX_INCLUDE_PAUTH_REGS
bl pauth_context_save
#endif
#if ENABLE_PAUTH
bl pauth_load_bl_apiakey
#endif
/* Setup exception class and syndrome arguments for platform handler */
mov x0, #ERROR_EA_ASYNC
mrs x1, esr_el3
adr x30, el3_exit
b delegate_async_ea
endfunc enter_lower_el_async_ea
/*
* Prelude for Synchronous External Abort handling. This function assumes that
* all GP registers have been saved by the caller.
*
* x0: EA reason
* x1: EA syndrome
*/
func delegate_sync_ea
#if RAS_EXTENSION
/*
* Check for Uncontainable error type. If so, route to the platform
* fatal error handler rather than the generic EA one.
*/
ubfx x2, x1, #EABORT_SET_SHIFT, #EABORT_SET_WIDTH
cmp x2, #ERROR_STATUS_SET_UC
b.ne 1f
/* Check fault status code */
ubfx x3, x1, #EABORT_DFSC_SHIFT, #EABORT_DFSC_WIDTH
cmp x3, #SYNC_EA_FSC
b.ne 1f
no_ret plat_handle_uncontainable_ea
1:
#endif
b ea_proceed
endfunc delegate_sync_ea
/*
* Prelude for Asynchronous External Abort handling. This function assumes that
* all GP registers have been saved by the caller.
*
* x0: EA reason
* x1: EA syndrome
*/
func delegate_async_ea
#if RAS_EXTENSION
/*
* Check for Implementation Defined Syndrome. If so, skip checking
* Uncontainable error type from the syndrome as the format is unknown.
*/
tbnz x1, #SERROR_IDS_BIT, 1f
/*
* Check for Uncontainable error type. If so, route to the platform
* fatal error handler rather than the generic EA one.
*/
ubfx x2, x1, #EABORT_AET_SHIFT, #EABORT_AET_WIDTH
cmp x2, #ERROR_STATUS_UET_UC
b.ne 1f
/* Check DFSC for SError type */
ubfx x3, x1, #EABORT_DFSC_SHIFT, #EABORT_DFSC_WIDTH
cmp x3, #DFSC_SERROR
b.ne 1f
no_ret plat_handle_uncontainable_ea
1:
#endif
b ea_proceed
endfunc delegate_async_ea
/*
* Delegate External Abort handling to platform's EA handler. This function
* assumes that all GP registers have been saved by the caller.
*
* x0: EA reason
* x1: EA syndrome
*/
func ea_proceed
/*
* If the ESR loaded earlier is not zero, we were processing an EA
* already, and this is a double fault.
*/
ldr x5, [sp, #CTX_EL3STATE_OFFSET + CTX_ESR_EL3]
cbz x5, 1f
no_ret plat_handle_double_fault
1:
/* Save EL3 state */
mrs x2, spsr_el3
mrs x3, elr_el3
stp x2, x3, [sp, #CTX_EL3STATE_OFFSET + CTX_SPSR_EL3]
/*
* Save ESR as handling might involve lower ELs, and returning back to
* EL3 from there would trample the original ESR.
*/
mrs x4, scr_el3
mrs x5, esr_el3
stp x4, x5, [sp, #CTX_EL3STATE_OFFSET + CTX_SCR_EL3]
/*
* Setup rest of arguments, and call platform External Abort handler.
*
* x0: EA reason (already in place)
* x1: Exception syndrome (already in place).
* x2: Cookie (unused for now).
* x3: Context pointer.
* x4: Flags (security state from SCR for now).
*/
mov x2, xzr
mov x3, sp
ubfx x4, x4, #0, #1
/* Switch to runtime stack */
ldr x5, [sp, #CTX_EL3STATE_OFFSET + CTX_RUNTIME_SP]
msr spsel, #0
mov sp, x5
mov x29, x30
#if ENABLE_ASSERTIONS
/* Stash the stack pointer */
mov x28, sp
#endif
bl plat_ea_handler
#if ENABLE_ASSERTIONS
/*
* Error handling flows might involve long jumps; so upon returning from
* the platform error handler, validate that the we've completely
* unwound the stack.
*/
mov x27, sp
cmp x28, x27
ASM_ASSERT(eq)
#endif
/* Make SP point to context */
msr spsel, #1
/* Restore EL3 state and ESR */
ldp x1, x2, [sp, #CTX_EL3STATE_OFFSET + CTX_SPSR_EL3]
msr spsr_el3, x1
msr elr_el3, x2
/* Restore ESR_EL3 and SCR_EL3 */
ldp x3, x4, [sp, #CTX_EL3STATE_OFFSET + CTX_SCR_EL3]
msr scr_el3, x3
msr esr_el3, x4
#if ENABLE_ASSERTIONS
cmp x4, xzr
ASM_ASSERT(ne)
#endif
/* Clear ESR storage */
str xzr, [sp, #CTX_EL3STATE_OFFSET + CTX_ESR_EL3]
ret x29
endfunc ea_proceed