gdb/arch/aarch64-insn.c

   1 /* Copyright (C) 2009-2021 Free Software Foundation, Inc.
   2    Contributed by ARM Ltd.
   3
   4    This file is part of GDB.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #include "gdbsupport/common-defs.h"
  20 #include "aarch64-insn.h"
  21
  22 /* Toggle this file's internal debugging dump.  */
  23 bool aarch64_debug = false;
  24
  25 /* Determine if specified bits within an instruction opcode matches a
  26    specific pattern.
  27
  28    INSN is the instruction opcode.
  29
  30    MASK specifies the bits within the opcode that are to be tested
  31    against for a match with PATTERN.  */
  32
  33 static int
  34 decode_masked_match (uint32_t insn, uint32_t mask, uint32_t pattern)
  35 {
  36   return (insn & mask) == pattern;
  37 }
  38
  39 /* Decode an opcode if it represents an ADR or ADRP instruction.
  40
  41    ADDR specifies the address of the opcode.
  42    INSN specifies the opcode to test.
  43    IS_ADRP receives the 'op' field from the decoded instruction.
  44    RD receives the 'rd' field from the decoded instruction.
  45    OFFSET receives the 'immhi:immlo' field from the decoded instruction.
  46
  47    Return 1 if the opcodes matches and is decoded, otherwise 0.  */
  48
  49 int
  50 aarch64_decode_adr (CORE_ADDR addr, uint32_t insn, int *is_adrp,
  51                     unsigned *rd, int32_t *offset)
  52 {
  53   /* adr  0ii1 0000 iiii iiii iiii iiii iiir rrrr */
  54   /* adrp 1ii1 0000 iiii iiii iiii iiii iiir rrrr */
  55   if (decode_masked_match (insn, 0x1f000000, 0x10000000))
  56     {
  57       uint32_t immlo = (insn >> 29) & 0x3;
  58       int32_t immhi = sbits (insn, 5, 23) * 4;
  59
  60       *is_adrp = (insn >> 31) & 0x1;
  61       *rd = (insn >> 0) & 0x1f;
  62
  63       if (*is_adrp)
  64         {
  65           /* The ADRP instruction has an offset with a -/+ 4GB range,
  66              encoded as (immhi:immlo * 4096).  */
  67           *offset = (immhi | immlo) * 4096;
  68         }
  69       else
  70         *offset = (immhi | immlo);
  71
  72       aarch64_debug_printf ("decode: 0x%s 0x%x %s x%u, #?",
  73                             core_addr_to_string_nz (addr), insn,
  74                             *is_adrp ?  "adrp" : "adr", *rd);
  75       return 1;
  76     }
  77   return 0;
  78 }
  79
  80 /* Decode an opcode if it represents an branch immediate or branch
  81    and link immediate instruction.
  82
  83    ADDR specifies the address of the opcode.
  84    INSN specifies the opcode to test.
  85    IS_BL receives the 'op' bit from the decoded instruction.
  86    OFFSET receives the immediate offset from the decoded instruction.
  87
  88    Return 1 if the opcodes matches and is decoded, otherwise 0.  */
  89
  90 int
  91 aarch64_decode_b (CORE_ADDR addr, uint32_t insn, int *is_bl,
  92                   int32_t *offset)
  93 {
  94   /* b  0001 01ii iiii iiii iiii iiii iiii iiii */
  95   /* bl 1001 01ii iiii iiii iiii iiii iiii iiii */
  96   if (decode_masked_match (insn, 0x7c000000, 0x14000000))
  97     {
  98       *is_bl = (insn >> 31) & 0x1;
  99       *offset = sbits (insn, 0, 25) * 4;
 100
 101       if (aarch64_debug)
 102         {
 103           debug_printf ("decode: 0x%s 0x%x %s 0x%s\n",
 104                         core_addr_to_string_nz (addr), insn,
 105                         *is_bl ? "bl" : "b",
 106                         core_addr_to_string_nz (addr + *offset));
 107         }
 108
 109       return 1;
 110     }
 111   return 0;
 112 }
 113
 114 /* Decode an opcode if it represents a conditional branch instruction.
 115
 116    ADDR specifies the address of the opcode.
 117    INSN specifies the opcode to test.
 118    COND receives the branch condition field from the decoded
 119    instruction.
 120    OFFSET receives the immediate offset from the decoded instruction.
 121
 122    Return 1 if the opcodes matches and is decoded, otherwise 0.  */
 123
 124 int
 125 aarch64_decode_bcond (CORE_ADDR addr, uint32_t insn, unsigned *cond,
 126                       int32_t *offset)
 127 {
 128   /* b.cond  0101 0100 iiii iiii iiii iiii iii0 cccc */
 129   if (decode_masked_match (insn, 0xff000010, 0x54000000))
 130     {
 131       *cond = (insn >> 0) & 0xf;
 132       *offset = sbits (insn, 5, 23) * 4;
 133
 134       if (aarch64_debug)
 135         {
 136           debug_printf ("decode: 0x%s 0x%x b<%u> 0x%s\n",
 137                         core_addr_to_string_nz (addr), insn, *cond,
 138                         core_addr_to_string_nz (addr + *offset));
 139         }
 140       return 1;
 141     }
 142   return 0;
 143 }
 144
 145 /* Decode an opcode if it represents a CBZ or CBNZ instruction.
 146
 147    ADDR specifies the address of the opcode.
 148    INSN specifies the opcode to test.
 149    IS64 receives the 'sf' field from the decoded instruction.
 150    IS_CBNZ receives the 'op' field from the decoded instruction.
 151    RN receives the 'rn' field from the decoded instruction.
 152    OFFSET receives the 'imm19' field from the decoded instruction.
 153
 154    Return 1 if the opcodes matches and is decoded, otherwise 0.  */
 155
 156 int
 157 aarch64_decode_cb (CORE_ADDR addr, uint32_t insn, int *is64, int *is_cbnz,
 158                    unsigned *rn, int32_t *offset)
 159 {
 160   /* cbz  T011 010o iiii iiii iiii iiii iiir rrrr */
 161   /* cbnz T011 010o iiii iiii iiii iiii iiir rrrr */
 162   if (decode_masked_match (insn, 0x7e000000, 0x34000000))
 163     {
 164       *rn = (insn >> 0) & 0x1f;
 165       *is64 = (insn >> 31) & 0x1;
 166       *is_cbnz = (insn >> 24) & 0x1;
 167       *offset = sbits (insn, 5, 23) * 4;
 168
 169       if (aarch64_debug)
 170         {
 171           debug_printf ("decode: 0x%s 0x%x %s 0x%s\n",
 172                         core_addr_to_string_nz (addr), insn,
 173                         *is_cbnz ? "cbnz" : "cbz",
 174                         core_addr_to_string_nz (addr + *offset));
 175         }
 176       return 1;
 177     }
 178   return 0;
 179 }
 180
 181 /* Decode an opcode if it represents a TBZ or TBNZ instruction.
 182
 183    ADDR specifies the address of the opcode.
 184    INSN specifies the opcode to test.
 185    IS_TBNZ receives the 'op' field from the decoded instruction.
 186    BIT receives the bit position field from the decoded instruction.
 187    RT receives 'rt' field from the decoded instruction.
 188    IMM receives 'imm' field from the decoded instruction.
 189
 190    Return 1 if the opcodes matches and is decoded, otherwise 0.  */
 191
 192 int
 193 aarch64_decode_tb (CORE_ADDR addr, uint32_t insn, int *is_tbnz,
 194                    unsigned *bit, unsigned *rt, int32_t *imm)
 195 {
 196   /* tbz  b011 0110 bbbb biii iiii iiii iiir rrrr */
 197   /* tbnz B011 0111 bbbb biii iiii iiii iiir rrrr */
 198   if (decode_masked_match (insn, 0x7e000000, 0x36000000))
 199     {
 200       *rt = (insn >> 0) & 0x1f;
 201       *is_tbnz = (insn >> 24) & 0x1;
 202       *bit = ((insn >> (31 - 4)) & 0x20) | ((insn >> 19) & 0x1f);
 203       *imm = sbits (insn, 5, 18) * 4;
 204
 205       if (aarch64_debug)
 206         {
 207           debug_printf ("decode: 0x%s 0x%x %s x%u, #%u, 0x%s\n",
 208                         core_addr_to_string_nz (addr), insn,
 209                         *is_tbnz ? "tbnz" : "tbz", *rt, *bit,
 210                         core_addr_to_string_nz (addr + *imm));
 211         }
 212       return 1;
 213     }
 214   return 0;
 215 }
 216
 217 /* Decode an opcode if it represents an LDR or LDRSW instruction taking a
 218    literal offset from the current PC.
 219
 220    ADDR specifies the address of the opcode.
 221    INSN specifies the opcode to test.
 222    IS_W is set if the instruction is LDRSW.
 223    IS64 receives size field from the decoded instruction.
 224    RT receives the 'rt' field from the decoded instruction.
 225    OFFSET receives the 'imm' field from the decoded instruction.
 226
 227    Return 1 if the opcodes matches and is decoded, otherwise 0.  */
 228
 229 int
 230 aarch64_decode_ldr_literal (CORE_ADDR addr, uint32_t insn, int *is_w,
 231                             int *is64, unsigned *rt, int32_t *offset)
 232 {
 233   /* LDR    0T01 1000 iiii iiii iiii iiii iiir rrrr */
 234   /* LDRSW  1001 1000 iiii iiii iiii iiii iiir rrrr */
 235   if ((insn & 0x3f000000) == 0x18000000)
 236     {
 237       *is_w = (insn >> 31) & 0x1;
 238
 239       if (*is_w)
 240         {
 241           /* LDRSW always takes a 64-bit destination registers.  */
 242           *is64 = 1;
 243         }
 244       else
 245         *is64 = (insn >> 30) & 0x1;
 246
 247       *rt = (insn >> 0) & 0x1f;
 248       *offset = sbits (insn, 5, 23) * 4;
 249
 250       if (aarch64_debug)
 251         debug_printf ("decode: %s 0x%x %s %s%u, #?\n",
 252                       core_addr_to_string_nz (addr), insn,
 253                       *is_w ? "ldrsw" : "ldr",
 254                       *is64 ? "x" : "w", *rt);
 255
 256       return 1;
 257     }
 258
 259   return 0;
 260 }
 261
 262 /* Visit an instruction INSN by VISITOR with all needed information in DATA.
 263
 264    PC relative instructions need to be handled specifically:
 265
 266    - B/BL
 267    - B.COND
 268    - CBZ/CBNZ
 269    - TBZ/TBNZ
 270    - ADR/ADRP
 271    - LDR/LDRSW (literal)  */
 272
 273 void
 274 aarch64_relocate_instruction (uint32_t insn,
 275                               const struct aarch64_insn_visitor *visitor,
 276                               struct aarch64_insn_data *data)
 277 {
 278   int is_bl;
 279   int is64;
 280   int is_sw;
 281   int is_cbnz;
 282   int is_tbnz;
 283   int is_adrp;
 284   unsigned rn;
 285   unsigned rt;
 286   unsigned rd;
 287   unsigned cond;
 288   unsigned bit;
 289   int32_t offset;
 290
 291   if (aarch64_decode_b (data->insn_addr, insn, &is_bl, &offset))
 292     visitor->b (is_bl, offset, data);
 293   else if (aarch64_decode_bcond (data->insn_addr, insn, &cond, &offset))
 294     visitor->b_cond (cond, offset, data);
 295   else if (aarch64_decode_cb (data->insn_addr, insn, &is64, &is_cbnz, &rn,
 296                               &offset))
 297     visitor->cb (offset, is_cbnz, rn, is64, data);
 298   else if (aarch64_decode_tb (data->insn_addr, insn, &is_tbnz, &bit, &rt,
 299                               &offset))
 300     visitor->tb (offset, is_tbnz, rt, bit, data);
 301   else if (aarch64_decode_adr (data->insn_addr, insn, &is_adrp, &rd, &offset))
 302     visitor->adr (offset, rd, is_adrp, data);
 303   else if (aarch64_decode_ldr_literal (data->insn_addr, insn, &is_sw, &is64,
 304                                        &rt, &offset))
 305     visitor->ldr_literal (offset, is_sw, rt, is64, data);
 306   else
 307     visitor->others (insn, data);
 308 }
 309
 310 /* Write a 32-bit unsigned integer INSN info *BUF.  Return the number of
 311    instructions written (aka. 1).  */
 312
 313 int
 314 aarch64_emit_insn (uint32_t *buf, uint32_t insn)
 315 {
 316   *buf = insn;
 317   return 1;
 318 }
 319
 320 /* Helper function emitting a load or store instruction.  */
 321
 322 int
 323 aarch64_emit_load_store (uint32_t *buf, uint32_t size,
 324                          enum aarch64_opcodes opcode,
 325                          struct aarch64_register rt,
 326                          struct aarch64_register rn,
 327                          struct aarch64_memory_operand operand)
 328 {
 329   uint32_t op;
 330
 331   switch (operand.type)
 332     {
 333     case MEMORY_OPERAND_OFFSET:
 334       {
 335         op = ENCODE (1, 1, 24);
 336
 337         return aarch64_emit_insn (buf, opcode | ENCODE (size, 2, 30) | op
 338                                   | ENCODE (operand.index >> 3, 12, 10)
 339                                   | ENCODE (rn.num, 5, 5)
 340                                   | ENCODE (rt.num, 5, 0));
 341       }
 342     case MEMORY_OPERAND_POSTINDEX:
 343       {
 344         uint32_t post_index = ENCODE (1, 2, 10);
 345
 346         op = ENCODE (0, 1, 24);
 347
 348         return aarch64_emit_insn (buf, opcode | ENCODE (size, 2, 30) | op
 349                                   | post_index | ENCODE (operand.index, 9, 12)
 350                                   | ENCODE (rn.num, 5, 5)
 351                                   | ENCODE (rt.num, 5, 0));
 352       }
 353     case MEMORY_OPERAND_PREINDEX:
 354       {
 355         uint32_t pre_index = ENCODE (3, 2, 10);
 356
 357         op = ENCODE (0, 1, 24);
 358
 359         return aarch64_emit_insn (buf, opcode | ENCODE (size, 2, 30) | op
 360                                   | pre_index | ENCODE (operand.index, 9, 12)
 361                                   | ENCODE (rn.num, 5, 5)
 362                                   | ENCODE (rt.num, 5, 0));
 363       }
 364     default:
 365       return 0;
 366     }
 367 }