1 /* SPDX-License-Identifier: GPL-2.0 */
2 #include <linux/linkage.h>
3 #include <asm/assembler.h>
4 /*
5 * Function: v4t_late_abort
6 *
7 * Params : r2 = pt_regs
8 * : r4 = aborted context pc
9 * : r5 = aborted context psr
10 *
11 * Returns : r4-r5, r9-r11, r13 preserved
12 *
13 * Purpose : obtain information about current aborted instruction.
14 * Note: we read user space. This means we might cause a data
15 * abort here if the I-TLB and D-TLB aren't seeing the same
16 * picture. Unfortunately, this does happen. We live with it.
17 */
18 ENTRY(v4t_late_abort)
19 tst r5, #PSR_T_BIT @ check for thumb mode
20 #ifdef CONFIG_CPU_CP15_MMU
21 mrc p15, 0, r1, c5, c0, 0 @ get FSR
22 mrc p15, 0, r0, c6, c0, 0 @ get FAR
23 bic r1, r1, #1 << 11 | 1 << 10 @ clear bits 11 and 10 of FSR
24 #else
25 mov r0, #0 @ clear r0, r1 (no FSR/FAR)
26 mov r1, #0
27 #endif
28 bne .data_thumb_abort
29 ldr r8, [r4] @ read arm instruction
30 uaccess_disable ip @ disable userspace access
31 tst r8, #1 << 20 @ L = 1 -> write?
32 orreq r1, r1, #1 << 11 @ yes.
33 and r7, r8, #15 << 24
34 add pc, pc, r7, lsr #22 @ Now branch to the relevant processing routine
35 nop
36
37 /* 0 */ b .data_arm_lateldrhpost @ ldrh rd, [rn], #m/rm
38 /* 1 */ b .data_arm_lateldrhpre @ ldrh rd, [rn, #m/rm]
39 /* 2 */ b .data_unknown
40 /* 3 */ b .data_unknown
41 /* 4 */ b .data_arm_lateldrpostconst @ ldr rd, [rn], #m
42 /* 5 */ b .data_arm_lateldrpreconst @ ldr rd, [rn, #m]
43 /* 6 */ b .data_arm_lateldrpostreg @ ldr rd, [rn], rm
44 /* 7 */ b .data_arm_lateldrprereg @ ldr rd, [rn, rm]
45 /* 8 */ b .data_arm_ldmstm @ ldm*a rn, <rlist>
46 /* 9 */ b .data_arm_ldmstm @ ldm*b rn, <rlist>
47 /* a */ b .data_unknown
48 /* b */ b .data_unknown
49 /* c */ b do_DataAbort @ ldc rd, [rn], #m @ Same as ldr rd, [rn], #m
50 /* d */ b do_DataAbort @ ldc rd, [rn, #m]
51 /* e */ b .data_unknown
52 /* f */ b .data_unknown
53
54 .data_unknown_r9:
55 ldr r9, [sp], #4
56 .data_unknown: @ Part of jumptable
57 mov r0, r4
58 mov r1, r8
59 b baddataabort
60
61 .data_arm_ldmstm:
62 tst r8, #1 << 21 @ check writeback bit
63 beq do_DataAbort @ no writeback -> no fixup
64 str r9, [sp, #-4]!
65 mov r7, #0x11
66 orr r7, r7, #0x1100
67 and r6, r8, r7
68 and r9, r8, r7, lsl #1
69 add r6, r6, r9, lsr #1
70 and r9, r8, r7, lsl #2
71 add r6, r6, r9, lsr #2
72 and r9, r8, r7, lsl #3
73 add r6, r6, r9, lsr #3
74 add r6, r6, r6, lsr #8
75 add r6, r6, r6, lsr #4
76 and r6, r6, #15 @ r6 = no. of registers to transfer.
77 and r9, r8, #15 << 16 @ Extract 'n' from instruction
78 ldr r7, [r2, r9, lsr #14] @ Get register 'Rn'
79 tst r8, #1 << 23 @ Check U bit
80 subne r7, r7, r6, lsl #2 @ Undo increment
81 addeq r7, r7, r6, lsl #2 @ Undo decrement
82 str r7, [r2, r9, lsr #14] @ Put register 'Rn'
83 ldr r9, [sp], #4
84 b do_DataAbort
85
86 .data_arm_lateldrhpre:
87 tst r8, #1 << 21 @ Check writeback bit
88 beq do_DataAbort @ No writeback -> no fixup
89 .data_arm_lateldrhpost:
90 str r9, [sp, #-4]!
91 and r9, r8, #0x00f @ get Rm / low nibble of immediate value
92 tst r8, #1 << 22 @ if (immediate offset)
93 andne r6, r8, #0xf00 @ { immediate high nibble
94 orrne r6, r9, r6, lsr #4 @ combine nibbles } else
95 ldreq r6, [r2, r9, lsl #2] @ { load Rm value }
96 .data_arm_apply_r6_and_rn:
97 and r9, r8, #15 << 16 @ Extract 'n' from instruction
98 ldr r7, [r2, r9, lsr #14] @ Get register 'Rn'
99 tst r8, #1 << 23 @ Check U bit
100 subne r7, r7, r6 @ Undo incrmenet
101 addeq r7, r7, r6 @ Undo decrement
102 str r7, [r2, r9, lsr #14] @ Put register 'Rn'
103 ldr r9, [sp], #4
104 b do_DataAbort
105
106 .data_arm_lateldrpreconst:
107 tst r8, #1 << 21 @ check writeback bit
108 beq do_DataAbort @ no writeback -> no fixup
109 .data_arm_lateldrpostconst:
110 movs r6, r8, lsl #20 @ Get offset
111 beq do_DataAbort @ zero -> no fixup
112 str r9, [sp, #-4]!
113 and r9, r8, #15 << 16 @ Extract 'n' from instruction
114 ldr r7, [r2, r9, lsr #14] @ Get register 'Rn'
115 tst r8, #1 << 23 @ Check U bit
116 subne r7, r7, r6, lsr #20 @ Undo increment
117 addeq r7, r7, r6, lsr #20 @ Undo decrement
118 str r7, [r2, r9, lsr #14] @ Put register 'Rn'
119 ldr r9, [sp], #4
120 b do_DataAbort
121
122 .data_arm_lateldrprereg:
123 tst r8, #1 << 21 @ check writeback bit
124 beq do_DataAbort @ no writeback -> no fixup
125 .data_arm_lateldrpostreg:
126 and r7, r8, #15 @ Extract 'm' from instruction
127 ldr r6, [r2, r7, lsl #2] @ Get register 'Rm'
128 str r9, [sp, #-4]!
129 mov r9, r8, lsr #7 @ get shift count
130 ands r9, r9, #31
131 and r7, r8, #0x70 @ get shift type
132 orreq r7, r7, #8 @ shift count = 0
133 add pc, pc, r7
134 nop
135
136 mov r6, r6, lsl r9 @ 0: LSL #!0
137 b .data_arm_apply_r6_and_rn
138 b .data_arm_apply_r6_and_rn @ 1: LSL #0
139 nop
140 b .data_unknown_r9 @ 2: MUL?
141 nop
142 b .data_unknown_r9 @ 3: MUL?
143 nop
144 mov r6, r6, lsr r9 @ 4: LSR #!0
145 b .data_arm_apply_r6_and_rn
146 mov r6, r6, lsr #32 @ 5: LSR #32
147 b .data_arm_apply_r6_and_rn
148 b .data_unknown_r9 @ 6: MUL?
149 nop
150 b .data_unknown_r9 @ 7: MUL?
151 nop
152 mov r6, r6, asr r9 @ 8: ASR #!0
153 b .data_arm_apply_r6_and_rn
154 mov r6, r6, asr #32 @ 9: ASR #32
155 b .data_arm_apply_r6_and_rn
156 b .data_unknown_r9 @ A: MUL?
157 nop
158 b .data_unknown_r9 @ B: MUL?
159 nop
160 mov r6, r6, ror r9 @ C: ROR #!0
161 b .data_arm_apply_r6_and_rn
162 mov r6, r6, rrx @ D: RRX
163 b .data_arm_apply_r6_and_rn
164 b .data_unknown_r9 @ E: MUL?
165 nop
166 b .data_unknown_r9 @ F: MUL?
167
168 .data_thumb_abort:
169 ldrh r8, [r4] @ read instruction
170 uaccess_disable ip @ disable userspace access
171 tst r8, #1 << 11 @ L = 1 -> write?
172 orreq r1, r1, #1 << 8 @ yes
173 and r7, r8, #15 << 12
174 add pc, pc, r7, lsr #10 @ lookup in table
175 nop
176
177 /* 0 */ b .data_unknown
178 /* 1 */ b .data_unknown
179 /* 2 */ b .data_unknown
180 /* 3 */ b .data_unknown
181 /* 4 */ b .data_unknown
182 /* 5 */ b .data_thumb_reg
183 /* 6 */ b do_DataAbort
184 /* 7 */ b do_DataAbort
185 /* 8 */ b do_DataAbort
186 /* 9 */ b do_DataAbort
187 /* A */ b .data_unknown
188 /* B */ b .data_thumb_pushpop
189 /* C */ b .data_thumb_ldmstm
190 /* D */ b .data_unknown
191 /* E */ b .data_unknown
192 /* F */ b .data_unknown
193
194 .data_thumb_reg:
195 tst r8, #1 << 9
196 beq do_DataAbort
197 tst r8, #1 << 10 @ If 'S' (signed) bit is set
198 movne r1, #0 @ it must be a load instr
199 b do_DataAbort
200
201 .data_thumb_pushpop:
202 tst r8, #1 << 10
203 beq .data_unknown
204 str r9, [sp, #-4]!
205 and r6, r8, #0x55 @ hweight8(r8) + R bit
206 and r9, r8, #0xaa
207 add r6, r6, r9, lsr #1
208 and r9, r6, #0xcc
209 and r6, r6, #0x33
210 add r6, r6, r9, lsr #2
211 movs r7, r8, lsr #9 @ C = r8 bit 8 (R bit)
212 adc r6, r6, r6, lsr #4 @ high + low nibble + R bit
213 and r6, r6, #15 @ number of regs to transfer
214 ldr r7, [r2, #13 << 2]
215 tst r8, #1 << 11
216 addeq r7, r7, r6, lsl #2 @ increment SP if PUSH
217 subne r7, r7, r6, lsl #2 @ decrement SP if POP
218 str r7, [r2, #13 << 2]
219 ldr r9, [sp], #4
220 b do_DataAbort
221
222 .data_thumb_ldmstm:
223 str r9, [sp, #-4]!
224 and r6, r8, #0x55 @ hweight8(r8)
225 and r9, r8, #0xaa
226 add r6, r6, r9, lsr #1
227 and r9, r6, #0xcc
228 and r6, r6, #0x33
229 add r6, r6, r9, lsr #2
230 add r6, r6, r6, lsr #4
231 and r9, r8, #7 << 8
232 ldr r7, [r2, r9, lsr #6]
233 and r6, r6, #15 @ number of regs to transfer
234 sub r7, r7, r6, lsl #2 @ always decrement
235 str r7, [r2, r9, lsr #6]
236 ldr r9, [sp], #4
237 b do_DataAbort
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