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
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
|
/* Copyright (C) 2009-2019 Free Software Foundation, Inc.
Contributed by ARM Ltd.
This file is part of GDB.
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; either version 3 of the License, or
(at your option) any later version.
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.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "gdbsupport/common-defs.h"
#include "aarch64-insn.h"
/* Toggle this file's internal debugging dump. */
bool aarch64_debug = false;
/* Extract a signed value from a bit field within an instruction
encoding.
INSN is the instruction opcode.
WIDTH specifies the width of the bit field to extract (in bits).
OFFSET specifies the least significant bit of the field where bits
are numbered zero counting from least to most significant. */
static int32_t
extract_signed_bitfield (uint32_t insn, unsigned width, unsigned offset)
{
unsigned shift_l = sizeof (int32_t) * 8 - (offset + width);
unsigned shift_r = sizeof (int32_t) * 8 - width;
return ((int32_t) insn << shift_l) >> shift_r;
}
/* Determine if specified bits within an instruction opcode matches a
specific pattern.
INSN is the instruction opcode.
MASK specifies the bits within the opcode that are to be tested
against for a match with PATTERN. */
static int
decode_masked_match (uint32_t insn, uint32_t mask, uint32_t pattern)
{
return (insn & mask) == pattern;
}
/* Decode an opcode if it represents an ADR or ADRP instruction.
ADDR specifies the address of the opcode.
INSN specifies the opcode to test.
IS_ADRP receives the 'op' field from the decoded instruction.
RD receives the 'rd' field from the decoded instruction.
OFFSET receives the 'immhi:immlo' field from the decoded instruction.
Return 1 if the opcodes matches and is decoded, otherwise 0. */
int
aarch64_decode_adr (CORE_ADDR addr, uint32_t insn, int *is_adrp,
unsigned *rd, int32_t *offset)
{
/* adr 0ii1 0000 iiii iiii iiii iiii iiir rrrr */
/* adrp 1ii1 0000 iiii iiii iiii iiii iiir rrrr */
if (decode_masked_match (insn, 0x1f000000, 0x10000000))
{
uint32_t immlo = (insn >> 29) & 0x3;
int32_t immhi = extract_signed_bitfield (insn, 19, 5) << 2;
*is_adrp = (insn >> 31) & 0x1;
*rd = (insn >> 0) & 0x1f;
if (*is_adrp)
{
/* The ADRP instruction has an offset with a -/+ 4GB range,
encoded as (immhi:immlo * 4096). */
*offset = (immhi | immlo) * 4096;
}
else
*offset = (immhi | immlo);
if (aarch64_debug)
{
debug_printf ("decode: 0x%s 0x%x %s x%u, #?\n",
core_addr_to_string_nz (addr), insn,
*is_adrp ? "adrp" : "adr", *rd);
}
return 1;
}
return 0;
}
/* Decode an opcode if it represents an branch immediate or branch
and link immediate instruction.
ADDR specifies the address of the opcode.
INSN specifies the opcode to test.
IS_BL receives the 'op' bit from the decoded instruction.
OFFSET receives the immediate offset from the decoded instruction.
Return 1 if the opcodes matches and is decoded, otherwise 0. */
int
aarch64_decode_b (CORE_ADDR addr, uint32_t insn, int *is_bl,
int32_t *offset)
{
/* b 0001 01ii iiii iiii iiii iiii iiii iiii */
/* bl 1001 01ii iiii iiii iiii iiii iiii iiii */
if (decode_masked_match (insn, 0x7c000000, 0x14000000))
{
*is_bl = (insn >> 31) & 0x1;
*offset = extract_signed_bitfield (insn, 26, 0) << 2;
if (aarch64_debug)
{
debug_printf ("decode: 0x%s 0x%x %s 0x%s\n",
core_addr_to_string_nz (addr), insn,
*is_bl ? "bl" : "b",
core_addr_to_string_nz (addr + *offset));
}
return 1;
}
return 0;
}
/* Decode an opcode if it represents a conditional branch instruction.
ADDR specifies the address of the opcode.
INSN specifies the opcode to test.
COND receives the branch condition field from the decoded
instruction.
OFFSET receives the immediate offset from the decoded instruction.
Return 1 if the opcodes matches and is decoded, otherwise 0. */
int
aarch64_decode_bcond (CORE_ADDR addr, uint32_t insn, unsigned *cond,
int32_t *offset)
{
/* b.cond 0101 0100 iiii iiii iiii iiii iii0 cccc */
if (decode_masked_match (insn, 0xff000010, 0x54000000))
{
*cond = (insn >> 0) & 0xf;
*offset = extract_signed_bitfield (insn, 19, 5) << 2;
if (aarch64_debug)
{
debug_printf ("decode: 0x%s 0x%x b<%u> 0x%s\n",
core_addr_to_string_nz (addr), insn, *cond,
core_addr_to_string_nz (addr + *offset));
}
return 1;
}
return 0;
}
/* Decode an opcode if it represents a CBZ or CBNZ instruction.
ADDR specifies the address of the opcode.
INSN specifies the opcode to test.
IS64 receives the 'sf' field from the decoded instruction.
IS_CBNZ receives the 'op' field from the decoded instruction.
RN receives the 'rn' field from the decoded instruction.
OFFSET receives the 'imm19' field from the decoded instruction.
Return 1 if the opcodes matches and is decoded, otherwise 0. */
int
aarch64_decode_cb (CORE_ADDR addr, uint32_t insn, int *is64, int *is_cbnz,
unsigned *rn, int32_t *offset)
{
/* cbz T011 010o iiii iiii iiii iiii iiir rrrr */
/* cbnz T011 010o iiii iiii iiii iiii iiir rrrr */
if (decode_masked_match (insn, 0x7e000000, 0x34000000))
{
*rn = (insn >> 0) & 0x1f;
*is64 = (insn >> 31) & 0x1;
*is_cbnz = (insn >> 24) & 0x1;
*offset = extract_signed_bitfield (insn, 19, 5) << 2;
if (aarch64_debug)
{
debug_printf ("decode: 0x%s 0x%x %s 0x%s\n",
core_addr_to_string_nz (addr), insn,
*is_cbnz ? "cbnz" : "cbz",
core_addr_to_string_nz (addr + *offset));
}
return 1;
}
return 0;
}
/* Decode an opcode if it represents a TBZ or TBNZ instruction.
ADDR specifies the address of the opcode.
INSN specifies the opcode to test.
IS_TBNZ receives the 'op' field from the decoded instruction.
BIT receives the bit position field from the decoded instruction.
RT receives 'rt' field from the decoded instruction.
IMM receives 'imm' field from the decoded instruction.
Return 1 if the opcodes matches and is decoded, otherwise 0. */
int
aarch64_decode_tb (CORE_ADDR addr, uint32_t insn, int *is_tbnz,
unsigned *bit, unsigned *rt, int32_t *imm)
{
/* tbz b011 0110 bbbb biii iiii iiii iiir rrrr */
/* tbnz B011 0111 bbbb biii iiii iiii iiir rrrr */
if (decode_masked_match (insn, 0x7e000000, 0x36000000))
{
*rt = (insn >> 0) & 0x1f;
*is_tbnz = (insn >> 24) & 0x1;
*bit = ((insn >> (31 - 4)) & 0x20) | ((insn >> 19) & 0x1f);
*imm = extract_signed_bitfield (insn, 14, 5) << 2;
if (aarch64_debug)
{
debug_printf ("decode: 0x%s 0x%x %s x%u, #%u, 0x%s\n",
core_addr_to_string_nz (addr), insn,
*is_tbnz ? "tbnz" : "tbz", *rt, *bit,
core_addr_to_string_nz (addr + *imm));
}
return 1;
}
return 0;
}
/* Decode an opcode if it represents an LDR or LDRSW instruction taking a
literal offset from the current PC.
ADDR specifies the address of the opcode.
INSN specifies the opcode to test.
IS_W is set if the instruction is LDRSW.
IS64 receives size field from the decoded instruction.
RT receives the 'rt' field from the decoded instruction.
OFFSET receives the 'imm' field from the decoded instruction.
Return 1 if the opcodes matches and is decoded, otherwise 0. */
int
aarch64_decode_ldr_literal (CORE_ADDR addr, uint32_t insn, int *is_w,
int *is64, unsigned *rt, int32_t *offset)
{
/* LDR 0T01 1000 iiii iiii iiii iiii iiir rrrr */
/* LDRSW 1001 1000 iiii iiii iiii iiii iiir rrrr */
if ((insn & 0x3f000000) == 0x18000000)
{
*is_w = (insn >> 31) & 0x1;
if (*is_w)
{
/* LDRSW always takes a 64-bit destination registers. */
*is64 = 1;
}
else
*is64 = (insn >> 30) & 0x1;
*rt = (insn >> 0) & 0x1f;
*offset = extract_signed_bitfield (insn, 19, 5) << 2;
if (aarch64_debug)
debug_printf ("decode: %s 0x%x %s %s%u, #?\n",
core_addr_to_string_nz (addr), insn,
*is_w ? "ldrsw" : "ldr",
*is64 ? "x" : "w", *rt);
return 1;
}
return 0;
}
/* Visit an instruction INSN by VISITOR with all needed information in DATA.
PC relative instructions need to be handled specifically:
- B/BL
- B.COND
- CBZ/CBNZ
- TBZ/TBNZ
- ADR/ADRP
- LDR/LDRSW (literal) */
void
aarch64_relocate_instruction (uint32_t insn,
const struct aarch64_insn_visitor *visitor,
struct aarch64_insn_data *data)
{
int is_bl;
int is64;
int is_sw;
int is_cbnz;
int is_tbnz;
int is_adrp;
unsigned rn;
unsigned rt;
unsigned rd;
unsigned cond;
unsigned bit;
int32_t offset;
if (aarch64_decode_b (data->insn_addr, insn, &is_bl, &offset))
visitor->b (is_bl, offset, data);
else if (aarch64_decode_bcond (data->insn_addr, insn, &cond, &offset))
visitor->b_cond (cond, offset, data);
else if (aarch64_decode_cb (data->insn_addr, insn, &is64, &is_cbnz, &rn,
&offset))
visitor->cb (offset, is_cbnz, rn, is64, data);
else if (aarch64_decode_tb (data->insn_addr, insn, &is_tbnz, &bit, &rt,
&offset))
visitor->tb (offset, is_tbnz, rt, bit, data);
else if (aarch64_decode_adr (data->insn_addr, insn, &is_adrp, &rd, &offset))
visitor->adr (offset, rd, is_adrp, data);
else if (aarch64_decode_ldr_literal (data->insn_addr, insn, &is_sw, &is64,
&rt, &offset))
visitor->ldr_literal (offset, is_sw, rt, is64, data);
else
visitor->others (insn, data);
}
/* Write a 32-bit unsigned integer INSN info *BUF. Return the number of
instructions written (aka. 1). */
int
aarch64_emit_insn (uint32_t *buf, uint32_t insn)
{
*buf = insn;
return 1;
}
/* Helper function emitting a load or store instruction. */
int
aarch64_emit_load_store (uint32_t *buf, uint32_t size,
enum aarch64_opcodes opcode,
struct aarch64_register rt,
struct aarch64_register rn,
struct aarch64_memory_operand operand)
{
uint32_t op;
switch (operand.type)
{
case MEMORY_OPERAND_OFFSET:
{
op = ENCODE (1, 1, 24);
return aarch64_emit_insn (buf, opcode | ENCODE (size, 2, 30) | op
| ENCODE (operand.index >> 3, 12, 10)
| ENCODE (rn.num, 5, 5)
| ENCODE (rt.num, 5, 0));
}
case MEMORY_OPERAND_POSTINDEX:
{
uint32_t post_index = ENCODE (1, 2, 10);
op = ENCODE (0, 1, 24);
return aarch64_emit_insn (buf, opcode | ENCODE (size, 2, 30) | op
| post_index | ENCODE (operand.index, 9, 12)
| ENCODE (rn.num, 5, 5)
| ENCODE (rt.num, 5, 0));
}
case MEMORY_OPERAND_PREINDEX:
{
uint32_t pre_index = ENCODE (3, 2, 10);
op = ENCODE (0, 1, 24);
return aarch64_emit_insn (buf, opcode | ENCODE (size, 2, 30) | op
| pre_index | ENCODE (operand.index, 9, 12)
| ENCODE (rn.num, 5, 5)
| ENCODE (rt.num, 5, 0));
}
default:
return 0;
}
}
|