gdbserver/ax.cc

   1 /* Agent expression code for remote server.
   2    Copyright (C) 2009-2021 Free Software Foundation, Inc.
   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 "server.h"
  20 #include "ax.h"
  21 #include "gdbsupport/format.h"
  22 #include "tracepoint.h"
  23 #include "gdbsupport/rsp-low.h"
  24
  25 static void ax_vdebug (const char *, ...) ATTRIBUTE_PRINTF (1, 2);
  26
  27 #ifdef IN_PROCESS_AGENT
  28 bool debug_agent = 0;
  29 #endif
  30
  31 static void
  32 ax_vdebug (const char *fmt, ...)
  33 {
  34   char buf[1024];
  35   va_list ap;
  36
  37   va_start (ap, fmt);
  38   vsprintf (buf, fmt, ap);
  39 #ifdef IN_PROCESS_AGENT
  40   fprintf (stderr, PROG "/ax: %s\n", buf);
  41 #else
  42   debug_printf (PROG "/ax: %s\n", buf);
  43 #endif
  44   va_end (ap);
  45 }
  46
  47 #define ax_debug_1(level, fmt, args...) \
  48   do {                                          \
  49     if (level <= debug_threads)                 \
  50       ax_vdebug ((fmt), ##args);                \
  51   } while (0)
  52
  53 #define ax_debug(FMT, args...)          \
  54   ax_debug_1 (1, FMT, ##args)
  55
  56 /* This enum must exactly match what is documented in
  57    gdb/doc/agentexpr.texi, including all the numerical values.  */
  58
  59 enum gdb_agent_op
  60   {
  61 #define DEFOP(NAME, SIZE, DATA_SIZE, CONSUMED, PRODUCED, VALUE)  \
  62     gdb_agent_op_ ## NAME = VALUE,
  63 #include "gdbsupport/ax.def"
  64 #undef DEFOP
  65     gdb_agent_op_last
  66   };
  67
  68 static const char * const gdb_agent_op_names [gdb_agent_op_last] =
  69   {
  70     "?undef?"
  71 #define DEFOP(NAME, SIZE, DATA_SIZE, CONSUMED, PRODUCED, VALUE)  , # NAME
  72 #include "gdbsupport/ax.def"
  73 #undef DEFOP
  74   };
  75
  76 #ifndef IN_PROCESS_AGENT
  77 static const unsigned char gdb_agent_op_sizes [gdb_agent_op_last] =
  78   {
  79     0
  80 #define DEFOP(NAME, SIZE, DATA_SIZE, CONSUMED, PRODUCED, VALUE)  , SIZE
  81 #include "gdbsupport/ax.def"
  82 #undef DEFOP
  83   };
  84 #endif
  85
  86 /* A wrapper for gdb_agent_op_names that does some bounds-checking.  */
  87
  88 static const char *
  89 gdb_agent_op_name (int op)
  90 {
  91   if (op < 0 || op >= gdb_agent_op_last || gdb_agent_op_names[op] == NULL)
  92     return "?undef?";
  93   return gdb_agent_op_names[op];
  94 }
  95
  96 #ifndef IN_PROCESS_AGENT
  97
  98 /* The packet form of an agent expression consists of an 'X', number
  99    of bytes in expression, a comma, and then the bytes.  */
 100
 101 struct agent_expr *
 102 gdb_parse_agent_expr (const char **actparm)
 103 {
 104   const char *act = *actparm;
 105   ULONGEST xlen;
 106   struct agent_expr *aexpr;
 107
 108   ++act;  /* skip the X */
 109   act = unpack_varlen_hex (act, &xlen);
 110   ++act;  /* skip a comma */
 111   aexpr = XNEW (struct agent_expr);
 112   aexpr->length = xlen;
 113   aexpr->bytes = (unsigned char *) xmalloc (xlen);
 114   hex2bin (act, aexpr->bytes, xlen);
 115   *actparm = act + (xlen * 2);
 116   return aexpr;
 117 }
 118
 119 void
 120 gdb_free_agent_expr (struct agent_expr *aexpr)
 121 {
 122   if (aexpr != NULL)
 123     {
 124       free (aexpr->bytes);
 125       free (aexpr);
 126     }
 127 }
 128
 129 /* Convert the bytes of an agent expression back into hex digits, so
 130    they can be printed or uploaded.  This allocates the buffer,
 131    callers should free when they are done with it.  */
 132
 133 char *
 134 gdb_unparse_agent_expr (struct agent_expr *aexpr)
 135 {
 136   char *rslt;
 137
 138   rslt = (char *) xmalloc (2 * aexpr->length + 1);
 139   bin2hex (aexpr->bytes, rslt, aexpr->length);
 140   return rslt;
 141 }
 142
 143 /* Bytecode compilation.  */
 144
 145 CORE_ADDR current_insn_ptr;
 146
 147 int emit_error;
 148
 149 static struct bytecode_address
 150 {
 151   int pc;
 152   CORE_ADDR address;
 153   int goto_pc;
 154   /* Offset and size of field to be modified in the goto block.  */
 155   int from_offset, from_size;
 156   struct bytecode_address *next;
 157 } *bytecode_address_table;
 158
 159 void
 160 emit_prologue (void)
 161 {
 162   target_emit_ops ()->emit_prologue ();
 163 }
 164
 165 void
 166 emit_epilogue (void)
 167 {
 168   target_emit_ops ()->emit_epilogue ();
 169 }
 170
 171 static void
 172 emit_add (void)
 173 {
 174   target_emit_ops ()->emit_add ();
 175 }
 176
 177 static void
 178 emit_sub (void)
 179 {
 180   target_emit_ops ()->emit_sub ();
 181 }
 182
 183 static void
 184 emit_mul (void)
 185 {
 186   target_emit_ops ()->emit_mul ();
 187 }
 188
 189 static void
 190 emit_lsh (void)
 191 {
 192   target_emit_ops ()->emit_lsh ();
 193 }
 194
 195 static void
 196 emit_rsh_signed (void)
 197 {
 198   target_emit_ops ()->emit_rsh_signed ();
 199 }
 200
 201 static void
 202 emit_rsh_unsigned (void)
 203 {
 204   target_emit_ops ()->emit_rsh_unsigned ();
 205 }
 206
 207 static void
 208 emit_ext (int arg)
 209 {
 210   target_emit_ops ()->emit_ext (arg);
 211 }
 212
 213 static void
 214 emit_log_not (void)
 215 {
 216   target_emit_ops ()->emit_log_not ();
 217 }
 218
 219 static void
 220 emit_bit_and (void)
 221 {
 222   target_emit_ops ()->emit_bit_and ();
 223 }
 224
 225 static void
 226 emit_bit_or (void)
 227 {
 228   target_emit_ops ()->emit_bit_or ();
 229 }
 230
 231 static void
 232 emit_bit_xor (void)
 233 {
 234   target_emit_ops ()->emit_bit_xor ();
 235 }
 236
 237 static void
 238 emit_bit_not (void)
 239 {
 240   target_emit_ops ()->emit_bit_not ();
 241 }
 242
 243 static void
 244 emit_equal (void)
 245 {
 246   target_emit_ops ()->emit_equal ();
 247 }
 248
 249 static void
 250 emit_less_signed (void)
 251 {
 252   target_emit_ops ()->emit_less_signed ();
 253 }
 254
 255 static void
 256 emit_less_unsigned (void)
 257 {
 258   target_emit_ops ()->emit_less_unsigned ();
 259 }
 260
 261 static void
 262 emit_ref (int size)
 263 {
 264   target_emit_ops ()->emit_ref (size);
 265 }
 266
 267 static void
 268 emit_if_goto (int *offset_p, int *size_p)
 269 {
 270   target_emit_ops ()->emit_if_goto (offset_p, size_p);
 271 }
 272
 273 static void
 274 emit_goto (int *offset_p, int *size_p)
 275 {
 276   target_emit_ops ()->emit_goto (offset_p, size_p);
 277 }
 278
 279 static void
 280 write_goto_address (CORE_ADDR from, CORE_ADDR to, int size)
 281 {
 282   target_emit_ops ()->write_goto_address (from, to, size);
 283 }
 284
 285 static void
 286 emit_const (LONGEST num)
 287 {
 288   target_emit_ops ()->emit_const (num);
 289 }
 290
 291 static void
 292 emit_reg (int reg)
 293 {
 294   target_emit_ops ()->emit_reg (reg);
 295 }
 296
 297 static void
 298 emit_pop (void)
 299 {
 300   target_emit_ops ()->emit_pop ();
 301 }
 302
 303 static void
 304 emit_stack_flush (void)
 305 {
 306   target_emit_ops ()->emit_stack_flush ();
 307 }
 308
 309 static void
 310 emit_zero_ext (int arg)
 311 {
 312   target_emit_ops ()->emit_zero_ext (arg);
 313 }
 314
 315 static void
 316 emit_swap (void)
 317 {
 318   target_emit_ops ()->emit_swap ();
 319 }
 320
 321 static void
 322 emit_stack_adjust (int n)
 323 {
 324   target_emit_ops ()->emit_stack_adjust (n);
 325 }
 326
 327 /* FN's prototype is `LONGEST(*fn)(int)'.  */
 328
 329 static void
 330 emit_int_call_1 (CORE_ADDR fn, int arg1)
 331 {
 332   target_emit_ops ()->emit_int_call_1 (fn, arg1);
 333 }
 334
 335 /* FN's prototype is `void(*fn)(int,LONGEST)'.  */
 336
 337 static void
 338 emit_void_call_2 (CORE_ADDR fn, int arg1)
 339 {
 340   target_emit_ops ()->emit_void_call_2 (fn, arg1);
 341 }
 342
 343 static void
 344 emit_eq_goto (int *offset_p, int *size_p)
 345 {
 346   target_emit_ops ()->emit_eq_goto (offset_p, size_p);
 347 }
 348
 349 static void
 350 emit_ne_goto (int *offset_p, int *size_p)
 351 {
 352   target_emit_ops ()->emit_ne_goto (offset_p, size_p);
 353 }
 354
 355 static void
 356 emit_lt_goto (int *offset_p, int *size_p)
 357 {
 358   target_emit_ops ()->emit_lt_goto (offset_p, size_p);
 359 }
 360
 361 static void
 362 emit_ge_goto (int *offset_p, int *size_p)
 363 {
 364   target_emit_ops ()->emit_ge_goto (offset_p, size_p);
 365 }
 366
 367 static void
 368 emit_gt_goto (int *offset_p, int *size_p)
 369 {
 370   target_emit_ops ()->emit_gt_goto (offset_p, size_p);
 371 }
 372
 373 static void
 374 emit_le_goto (int *offset_p, int *size_p)
 375 {
 376   target_emit_ops ()->emit_le_goto (offset_p, size_p);
 377 }
 378
 379 /* Scan an agent expression for any evidence that the given PC is the
 380    target of a jump bytecode in the expression.  */
 381
 382 static int
 383 is_goto_target (struct agent_expr *aexpr, int pc)
 384 {
 385   int i;
 386   unsigned char op;
 387
 388   for (i = 0; i < aexpr->length; i += 1 + gdb_agent_op_sizes[op])
 389     {
 390       op = aexpr->bytes[i];
 391
 392       if (op == gdb_agent_op_goto || op == gdb_agent_op_if_goto)
 393         {
 394           int target = (aexpr->bytes[i + 1] << 8) + aexpr->bytes[i + 2];
 395           if (target == pc)
 396             return 1;
 397         }
 398     }
 399
 400   return 0;
 401 }
 402
 403 /* Given an agent expression, turn it into native code.  */
 404
 405 enum eval_result_type
 406 compile_bytecodes (struct agent_expr *aexpr)
 407 {
 408   int pc = 0;
 409   int done = 0;
 410   unsigned char op, next_op;
 411   int arg;
 412   /* This is only used to build 64-bit value for constants.  */
 413   ULONGEST top;
 414   struct bytecode_address *aentry, *aentry2;
 415
 416 #define UNHANDLED                                       \
 417   do                                                    \
 418     {                                                   \
 419       ax_debug ("Cannot compile op 0x%x\n", op);        \
 420       return expr_eval_unhandled_opcode;                \
 421     } while (0)
 422
 423   if (aexpr->length == 0)
 424     {
 425       ax_debug ("empty agent expression\n");
 426       return expr_eval_empty_expression;
 427     }
 428
 429   bytecode_address_table = NULL;
 430
 431   while (!done)
 432     {
 433       op = aexpr->bytes[pc];
 434
 435       ax_debug ("About to compile op 0x%x, pc=%d\n", op, pc);
 436
 437       /* Record the compiled-code address of the bytecode, for use by
 438          jump instructions.  */
 439       aentry = XNEW (struct bytecode_address);
 440       aentry->pc = pc;
 441       aentry->address = current_insn_ptr;
 442       aentry->goto_pc = -1;
 443       aentry->from_offset = aentry->from_size = 0;
 444       aentry->next = bytecode_address_table;
 445       bytecode_address_table = aentry;
 446
 447       ++pc;
 448
 449       emit_error = 0;
 450
 451       switch (op)
 452         {
 453         case gdb_agent_op_add:
 454           emit_add ();
 455           break;
 456
 457         case gdb_agent_op_sub:
 458           emit_sub ();
 459           break;
 460
 461         case gdb_agent_op_mul:
 462           emit_mul ();
 463           break;
 464
 465         case gdb_agent_op_div_signed:
 466           UNHANDLED;
 467           break;
 468
 469         case gdb_agent_op_div_unsigned:
 470           UNHANDLED;
 471           break;
 472
 473         case gdb_agent_op_rem_signed:
 474           UNHANDLED;
 475           break;
 476
 477         case gdb_agent_op_rem_unsigned:
 478           UNHANDLED;
 479           break;
 480
 481         case gdb_agent_op_lsh:
 482           emit_lsh ();
 483           break;
 484
 485         case gdb_agent_op_rsh_signed:
 486           emit_rsh_signed ();
 487           break;
 488
 489         case gdb_agent_op_rsh_unsigned:
 490           emit_rsh_unsigned ();
 491           break;
 492
 493         case gdb_agent_op_trace:
 494           UNHANDLED;
 495           break;
 496
 497         case gdb_agent_op_trace_quick:
 498           UNHANDLED;
 499           break;
 500
 501         case gdb_agent_op_log_not:
 502           emit_log_not ();
 503           break;
 504
 505         case gdb_agent_op_bit_and:
 506           emit_bit_and ();
 507           break;
 508
 509         case gdb_agent_op_bit_or:
 510           emit_bit_or ();
 511           break;
 512
 513         case gdb_agent_op_bit_xor:
 514           emit_bit_xor ();
 515           break;
 516
 517         case gdb_agent_op_bit_not:
 518           emit_bit_not ();
 519           break;
 520
 521         case gdb_agent_op_equal:
 522           next_op = aexpr->bytes[pc];
 523           if (next_op == gdb_agent_op_if_goto
 524               && !is_goto_target (aexpr, pc)
 525               && target_emit_ops ()->emit_eq_goto)
 526             {
 527               ax_debug ("Combining equal & if_goto");
 528               pc += 1;
 529               aentry->pc = pc;
 530               arg = aexpr->bytes[pc++];
 531               arg = (arg << 8) + aexpr->bytes[pc++];
 532               aentry->goto_pc = arg;
 533               emit_eq_goto (&(aentry->from_offset), &(aentry->from_size));
 534             }
 535           else if (next_op == gdb_agent_op_log_not
 536                    && (aexpr->bytes[pc + 1] == gdb_agent_op_if_goto)
 537                    && !is_goto_target (aexpr, pc + 1)
 538                    && target_emit_ops ()->emit_ne_goto)
 539             {
 540               ax_debug ("Combining equal & log_not & if_goto");
 541               pc += 2;
 542               aentry->pc = pc;
 543               arg = aexpr->bytes[pc++];
 544               arg = (arg << 8) + aexpr->bytes[pc++];
 545               aentry->goto_pc = arg;
 546               emit_ne_goto (&(aentry->from_offset), &(aentry->from_size));
 547             }
 548           else
 549             emit_equal ();
 550           break;
 551
 552         case gdb_agent_op_less_signed:
 553           next_op = aexpr->bytes[pc];
 554           if (next_op == gdb_agent_op_if_goto
 555               && !is_goto_target (aexpr, pc))
 556             {
 557               ax_debug ("Combining less_signed & if_goto");
 558               pc += 1;
 559               aentry->pc = pc;
 560               arg = aexpr->bytes[pc++];
 561               arg = (arg << 8) + aexpr->bytes[pc++];
 562               aentry->goto_pc = arg;
 563               emit_lt_goto (&(aentry->from_offset), &(aentry->from_size));
 564             }
 565           else if (next_op == gdb_agent_op_log_not
 566                    && !is_goto_target (aexpr, pc)
 567                    && (aexpr->bytes[pc + 1] == gdb_agent_op_if_goto)
 568                    && !is_goto_target (aexpr, pc + 1))
 569             {
 570               ax_debug ("Combining less_signed & log_not & if_goto");
 571               pc += 2;
 572               aentry->pc = pc;
 573               arg = aexpr->bytes[pc++];
 574               arg = (arg << 8) + aexpr->bytes[pc++];
 575               aentry->goto_pc = arg;
 576               emit_ge_goto (&(aentry->from_offset), &(aentry->from_size));
 577             }
 578           else
 579             emit_less_signed ();
 580           break;
 581
 582         case gdb_agent_op_less_unsigned:
 583           emit_less_unsigned ();
 584           break;
 585
 586         case gdb_agent_op_ext:
 587           arg = aexpr->bytes[pc++];
 588           if (arg < (sizeof (LONGEST) * 8))
 589             emit_ext (arg);
 590           break;
 591
 592         case gdb_agent_op_ref8:
 593           emit_ref (1);
 594           break;
 595
 596         case gdb_agent_op_ref16:
 597           emit_ref (2);
 598           break;
 599
 600         case gdb_agent_op_ref32:
 601           emit_ref (4);
 602           break;
 603
 604         case gdb_agent_op_ref64:
 605           emit_ref (8);
 606           break;
 607
 608         case gdb_agent_op_if_goto:
 609           arg = aexpr->bytes[pc++];
 610           arg = (arg << 8) + aexpr->bytes[pc++];
 611           aentry->goto_pc = arg;
 612           emit_if_goto (&(aentry->from_offset), &(aentry->from_size));
 613           break;
 614
 615         case gdb_agent_op_goto:
 616           arg = aexpr->bytes[pc++];
 617           arg = (arg << 8) + aexpr->bytes[pc++];
 618           aentry->goto_pc = arg;
 619           emit_goto (&(aentry->from_offset), &(aentry->from_size));
 620           break;
 621
 622         case gdb_agent_op_const8:
 623           emit_stack_flush ();
 624           top = aexpr->bytes[pc++];
 625           emit_const (top);
 626           break;
 627
 628         case gdb_agent_op_const16:
 629           emit_stack_flush ();
 630           top = aexpr->bytes[pc++];
 631           top = (top << 8) + aexpr->bytes[pc++];
 632           emit_const (top);
 633           break;
 634
 635         case gdb_agent_op_const32:
 636           emit_stack_flush ();
 637           top = aexpr->bytes[pc++];
 638           top = (top << 8) + aexpr->bytes[pc++];
 639           top = (top << 8) + aexpr->bytes[pc++];
 640           top = (top << 8) + aexpr->bytes[pc++];
 641           emit_const (top);
 642           break;
 643
 644         case gdb_agent_op_const64:
 645           emit_stack_flush ();
 646           top = aexpr->bytes[pc++];
 647           top = (top << 8) + aexpr->bytes[pc++];
 648           top = (top << 8) + aexpr->bytes[pc++];
 649           top = (top << 8) + aexpr->bytes[pc++];
 650           top = (top << 8) + aexpr->bytes[pc++];
 651           top = (top << 8) + aexpr->bytes[pc++];
 652           top = (top << 8) + aexpr->bytes[pc++];
 653           top = (top << 8) + aexpr->bytes[pc++];
 654           emit_const (top);
 655           break;
 656
 657         case gdb_agent_op_reg:
 658           emit_stack_flush ();
 659           arg = aexpr->bytes[pc++];
 660           arg = (arg << 8) + aexpr->bytes[pc++];
 661           emit_reg (arg);
 662           break;
 663
 664         case gdb_agent_op_end:
 665           ax_debug ("At end of expression\n");
 666
 667           /* Assume there is one stack element left, and that it is
 668              cached in "top" where emit_epilogue can get to it.  */
 669           emit_stack_adjust (1);
 670
 671           done = 1;
 672           break;
 673
 674         case gdb_agent_op_dup:
 675           /* In our design, dup is equivalent to stack flushing.  */
 676           emit_stack_flush ();
 677           break;
 678
 679         case gdb_agent_op_pop:
 680           emit_pop ();
 681           break;
 682
 683         case gdb_agent_op_zero_ext:
 684           arg = aexpr->bytes[pc++];
 685           if (arg < (sizeof (LONGEST) * 8))
 686             emit_zero_ext (arg);
 687           break;
 688
 689         case gdb_agent_op_swap:
 690           next_op = aexpr->bytes[pc];
 691           /* Detect greater-than comparison sequences.  */
 692           if (next_op == gdb_agent_op_less_signed
 693               && !is_goto_target (aexpr, pc)
 694               && (aexpr->bytes[pc + 1] == gdb_agent_op_if_goto)
 695               && !is_goto_target (aexpr, pc + 1))
 696             {
 697               ax_debug ("Combining swap & less_signed & if_goto");
 698               pc += 2;
 699               aentry->pc = pc;
 700               arg = aexpr->bytes[pc++];
 701               arg = (arg << 8) + aexpr->bytes[pc++];
 702               aentry->goto_pc = arg;
 703               emit_gt_goto (&(aentry->from_offset), &(aentry->from_size));
 704             }
 705           else if (next_op == gdb_agent_op_less_signed
 706                    && !is_goto_target (aexpr, pc)
 707                    && (aexpr->bytes[pc + 1] == gdb_agent_op_log_not)
 708                    && !is_goto_target (aexpr, pc + 1)
 709                    && (aexpr->bytes[pc + 2] == gdb_agent_op_if_goto)
 710                    && !is_goto_target (aexpr, pc + 2))
 711             {
 712               ax_debug ("Combining swap & less_signed & log_not & if_goto");
 713               pc += 3;
 714               aentry->pc = pc;
 715               arg = aexpr->bytes[pc++];
 716               arg = (arg << 8) + aexpr->bytes[pc++];
 717               aentry->goto_pc = arg;
 718               emit_le_goto (&(aentry->from_offset), &(aentry->from_size));
 719             }
 720           else
 721             emit_swap ();
 722           break;
 723
 724         case gdb_agent_op_getv:
 725           emit_stack_flush ();
 726           arg = aexpr->bytes[pc++];
 727           arg = (arg << 8) + aexpr->bytes[pc++];
 728           emit_int_call_1 (get_get_tsv_func_addr (),
 729                            arg);
 730           break;
 731
 732         case gdb_agent_op_setv:
 733           arg = aexpr->bytes[pc++];
 734           arg = (arg << 8) + aexpr->bytes[pc++];
 735           emit_void_call_2 (get_set_tsv_func_addr (),
 736                             arg);
 737           break;
 738
 739         case gdb_agent_op_tracev:
 740           UNHANDLED;
 741           break;
 742
 743           /* GDB never (currently) generates any of these ops.  */
 744         case gdb_agent_op_float:
 745         case gdb_agent_op_ref_float:
 746         case gdb_agent_op_ref_double:
 747         case gdb_agent_op_ref_long_double:
 748         case gdb_agent_op_l_to_d:
 749         case gdb_agent_op_d_to_l:
 750         case gdb_agent_op_trace16:
 751           UNHANDLED;
 752           break;
 753
 754         default:
 755           ax_debug ("Agent expression op 0x%x not recognized\n", op);
 756           /* Don't struggle on, things will just get worse.  */
 757           return expr_eval_unrecognized_opcode;
 758         }
 759
 760       /* This catches errors that occur in target-specific code
 761          emission.  */
 762       if (emit_error)
 763         {
 764           ax_debug ("Error %d while emitting code for %s\n",
 765                     emit_error, gdb_agent_op_name (op));
 766           return expr_eval_unhandled_opcode;
 767         }
 768
 769       ax_debug ("Op %s compiled\n", gdb_agent_op_name (op));
 770     }
 771
 772   /* Now fill in real addresses as goto destinations.  */
 773   for (aentry = bytecode_address_table; aentry; aentry = aentry->next)
 774     {
 775       int written = 0;
 776
 777       if (aentry->goto_pc < 0)
 778         continue;
 779
 780       /* Find the location that we are going to, and call back into
 781          target-specific code to write the actual address or
 782          displacement.  */
 783       for (aentry2 = bytecode_address_table; aentry2; aentry2 = aentry2->next)
 784         {
 785           if (aentry2->pc == aentry->goto_pc)
 786             {
 787               ax_debug ("Want to jump from %s to %s\n",
 788                         paddress (aentry->address),
 789                         paddress (aentry2->address));
 790               write_goto_address (aentry->address + aentry->from_offset,
 791                                   aentry2->address, aentry->from_size);
 792               written = 1;
 793               break;
 794             }
 795         }
 796
 797       /* Error out if we didn't find a destination.  */
 798       if (!written)
 799         {
 800           ax_debug ("Destination of goto %d not found\n",
 801                     aentry->goto_pc);
 802           return expr_eval_invalid_goto;
 803         }
 804     }
 805
 806   return expr_eval_no_error;
 807 }
 808
 809 #endif
 810
 811 /* Make printf-type calls using arguments supplied from the host.  We
 812    need to parse the format string ourselves, and call the formatting
 813    function with one argument at a time, partly because there is no
 814    safe portable way to construct a varargs call, and partly to serve
 815    as a security barrier against bad format strings that might get
 816    in.  */
 817
 818 static void
 819 ax_printf (CORE_ADDR fn, CORE_ADDR chan, const char *format,
 820            int nargs, ULONGEST *args)
 821 {
 822   const char *f = format;
 823   int i;
 824   const char *current_substring;
 825   int nargs_wanted;
 826
 827   ax_debug ("Printf of \"%s\" with %d args", format, nargs);
 828
 829   format_pieces fpieces (&f);
 830
 831   nargs_wanted = 0;
 832   for (auto &&piece : fpieces)
 833     if (piece.argclass != literal_piece)
 834       ++nargs_wanted;
 835
 836   if (nargs != nargs_wanted)
 837     error (_("Wrong number of arguments for specified format-string"));
 838
 839   i = 0;
 840   for (auto &&piece : fpieces)
 841     {
 842       current_substring = piece.string;
 843       ax_debug ("current substring is '%s', class is %d",
 844                 current_substring, piece.argclass);
 845       switch (piece.argclass)
 846         {
 847         case string_arg:
 848           {
 849             gdb_byte *str;
 850             CORE_ADDR tem;
 851             int j;
 852
 853             tem = args[i];
 854             if (tem == 0)
 855               {
 856                 printf (current_substring, "(null)");
 857                 break;
 858               }
 859
 860             /* This is a %s argument.  Find the length of the string.  */
 861             for (j = 0;; j++)
 862               {
 863                 gdb_byte c;
 864
 865                 read_inferior_memory (tem + j, &c, 1);
 866                 if (c == 0)
 867                   break;
 868               }
 869
 870               /* Copy the string contents into a string inside GDB.  */
 871               str = (gdb_byte *) alloca (j + 1);
 872               if (j != 0)
 873                 read_inferior_memory (tem, str, j);
 874               str[j] = 0;
 875
 876               printf (current_substring, (char *) str);
 877             }
 878             break;
 879
 880           case long_long_arg:
 881 #if defined (CC_HAS_LONG_LONG) && defined (PRINTF_HAS_LONG_LONG)
 882             {
 883               long long val = args[i];
 884
 885               printf (current_substring, val);
 886               break;
 887             }
 888 #else
 889             error (_("long long not supported in agent printf"));
 890 #endif
 891         case int_arg:
 892           {
 893             int val = args[i];
 894
 895             printf (current_substring, val);
 896             break;
 897           }
 898
 899         case long_arg:
 900           {
 901             long val = args[i];
 902
 903             printf (current_substring, val);
 904             break;
 905           }
 906
 907         case size_t_arg:
 908           {
 909             size_t val = args[i];
 910
 911             printf (current_substring, val);
 912             break;
 913           }
 914
 915         case literal_piece:
 916           /* Print a portion of the format string that has no
 917              directives.  Note that this will not include any
 918              ordinary %-specs, but it might include "%%".  That is
 919              why we use printf_filtered and not puts_filtered here.
 920              Also, we pass a dummy argument because some platforms
 921              have modified GCC to include -Wformat-security by
 922              default, which will warn here if there is no
 923              argument.  */
 924           printf (current_substring, 0);
 925           break;
 926
 927         default:
 928           error (_("Format directive in '%s' not supported in agent printf"),
 929                  current_substring);
 930         }
 931
 932       /* Maybe advance to the next argument.  */
 933       if (piece.argclass != literal_piece)
 934         ++i;
 935     }
 936
 937   fflush (stdout);
 938 }
 939
 940 /* The agent expression evaluator, as specified by the GDB docs. It
 941    returns 0 if everything went OK, and a nonzero error code
 942    otherwise.  */
 943
 944 enum eval_result_type
 945 gdb_eval_agent_expr (struct eval_agent_expr_context *ctx,
 946                      struct agent_expr *aexpr,
 947                      ULONGEST *rslt)
 948 {
 949   int pc = 0;
 950 #define STACK_MAX 100
 951   ULONGEST stack[STACK_MAX], top;
 952   int sp = 0;
 953   unsigned char op;
 954   int arg;
 955
 956   /* This union is a convenient way to convert representations.  For
 957      now, assume a standard architecture where the hardware integer
 958      types have 8, 16, 32, 64 bit types.  A more robust solution would
 959      be to import stdint.h from gnulib.  */
 960   union
 961   {
 962     union
 963     {
 964       unsigned char bytes[1];
 965       unsigned char val;
 966     } u8;
 967     union
 968     {
 969       unsigned char bytes[2];
 970       unsigned short val;
 971     } u16;
 972     union
 973     {
 974       unsigned char bytes[4];
 975       unsigned int val;
 976     } u32;
 977     union
 978     {
 979       unsigned char bytes[8];
 980       ULONGEST val;
 981     } u64;
 982   } cnv;
 983
 984   if (aexpr->length == 0)
 985     {
 986       ax_debug ("empty agent expression");
 987       return expr_eval_empty_expression;
 988     }
 989
 990   /* Cache the stack top in its own variable. Much of the time we can
 991      operate on this variable, rather than dinking with the stack. It
 992      needs to be copied to the stack when sp changes.  */
 993   top = 0;
 994
 995   while (1)
 996     {
 997       op = aexpr->bytes[pc++];
 998
 999       ax_debug ("About to interpret byte 0x%x", op);
1000
1001       switch (op)
1002         {
1003         case gdb_agent_op_add:
1004           top += stack[--sp];
1005           break;
1006
1007         case gdb_agent_op_sub:
1008           top = stack[--sp] - top;
1009           break;
1010
1011         case gdb_agent_op_mul:
1012           top *= stack[--sp];
1013           break;
1014
1015         case gdb_agent_op_div_signed:
1016           if (top == 0)
1017             {
1018               ax_debug ("Attempted to divide by zero");
1019               return expr_eval_divide_by_zero;
1020             }
1021           top = ((LONGEST) stack[--sp]) / ((LONGEST) top);
1022           break;
1023
1024         case gdb_agent_op_div_unsigned:
1025           if (top == 0)
1026             {
1027               ax_debug ("Attempted to divide by zero");
1028               return expr_eval_divide_by_zero;
1029             }
1030           top = stack[--sp] / top;
1031           break;
1032
1033         case gdb_agent_op_rem_signed:
1034           if (top == 0)
1035             {
1036               ax_debug ("Attempted to divide by zero");
1037               return expr_eval_divide_by_zero;
1038             }
1039           top = ((LONGEST) stack[--sp]) % ((LONGEST) top);
1040           break;
1041
1042         case gdb_agent_op_rem_unsigned:
1043           if (top == 0)
1044             {
1045               ax_debug ("Attempted to divide by zero");
1046               return expr_eval_divide_by_zero;
1047             }
1048           top = stack[--sp] % top;
1049           break;
1050
1051         case gdb_agent_op_lsh:
1052           top = stack[--sp] << top;
1053           break;
1054
1055         case gdb_agent_op_rsh_signed:
1056           top = ((LONGEST) stack[--sp]) >> top;
1057           break;
1058
1059         case gdb_agent_op_rsh_unsigned:
1060           top = stack[--sp] >> top;
1061           break;
1062
1063         case gdb_agent_op_trace:
1064           agent_mem_read (ctx, NULL, (CORE_ADDR) stack[--sp],
1065                           (ULONGEST) top);
1066           if (--sp >= 0)
1067             top = stack[sp];
1068           break;
1069
1070         case gdb_agent_op_trace_quick:
1071           arg = aexpr->bytes[pc++];
1072           agent_mem_read (ctx, NULL, (CORE_ADDR) top, (ULONGEST) arg);
1073           break;
1074
1075         case gdb_agent_op_log_not:
1076           top = !top;
1077           break;
1078
1079         case gdb_agent_op_bit_and:
1080           top &= stack[--sp];
1081           break;
1082
1083         case gdb_agent_op_bit_or:
1084           top |= stack[--sp];
1085           break;
1086
1087         case gdb_agent_op_bit_xor:
1088           top ^= stack[--sp];
1089           break;
1090
1091         case gdb_agent_op_bit_not:
1092           top = ~top;
1093           break;
1094
1095         case gdb_agent_op_equal:
1096           top = (stack[--sp] == top);
1097           break;
1098
1099         case gdb_agent_op_less_signed:
1100           top = (((LONGEST) stack[--sp]) < ((LONGEST) top));
1101           break;
1102
1103         case gdb_agent_op_less_unsigned:
1104           top = (stack[--sp] < top);
1105           break;
1106
1107         case gdb_agent_op_ext:
1108           arg = aexpr->bytes[pc++];
1109           if (arg < (sizeof (LONGEST) * 8))
1110             {
1111               LONGEST mask = 1 << (arg - 1);
1112               top &= ((LONGEST) 1 << arg) - 1;
1113               top = (top ^ mask) - mask;
1114             }
1115           break;
1116
1117         case gdb_agent_op_ref8:
1118           agent_mem_read (ctx, cnv.u8.bytes, (CORE_ADDR) top, 1);
1119           top = cnv.u8.val;
1120           break;
1121
1122         case gdb_agent_op_ref16:
1123           agent_mem_read (ctx, cnv.u16.bytes, (CORE_ADDR) top, 2);
1124           top = cnv.u16.val;
1125           break;
1126
1127         case gdb_agent_op_ref32:
1128           agent_mem_read (ctx, cnv.u32.bytes, (CORE_ADDR) top, 4);
1129           top = cnv.u32.val;
1130           break;
1131
1132         case gdb_agent_op_ref64:
1133           agent_mem_read (ctx, cnv.u64.bytes, (CORE_ADDR) top, 8);
1134           top = cnv.u64.val;
1135           break;
1136
1137         case gdb_agent_op_if_goto:
1138           if (top)
1139             pc = (aexpr->bytes[pc] << 8) + (aexpr->bytes[pc + 1]);
1140           else
1141             pc += 2;
1142           if (--sp >= 0)
1143             top = stack[sp];
1144           break;
1145
1146         case gdb_agent_op_goto:
1147           pc = (aexpr->bytes[pc] << 8) + (aexpr->bytes[pc + 1]);
1148           break;
1149
1150         case gdb_agent_op_const8:
1151           /* Flush the cached stack top.  */
1152           stack[sp++] = top;
1153           top = aexpr->bytes[pc++];
1154           break;
1155
1156         case gdb_agent_op_const16:
1157           /* Flush the cached stack top.  */
1158           stack[sp++] = top;
1159           top = aexpr->bytes[pc++];
1160           top = (top << 8) + aexpr->bytes[pc++];
1161           break;
1162
1163         case gdb_agent_op_const32:
1164           /* Flush the cached stack top.  */
1165           stack[sp++] = top;
1166           top = aexpr->bytes[pc++];
1167           top = (top << 8) + aexpr->bytes[pc++];
1168           top = (top << 8) + aexpr->bytes[pc++];
1169           top = (top << 8) + aexpr->bytes[pc++];
1170           break;
1171
1172         case gdb_agent_op_const64:
1173           /* Flush the cached stack top.  */
1174           stack[sp++] = top;
1175           top = aexpr->bytes[pc++];
1176           top = (top << 8) + aexpr->bytes[pc++];
1177           top = (top << 8) + aexpr->bytes[pc++];
1178           top = (top << 8) + aexpr->bytes[pc++];
1179           top = (top << 8) + aexpr->bytes[pc++];
1180           top = (top << 8) + aexpr->bytes[pc++];
1181           top = (top << 8) + aexpr->bytes[pc++];
1182           top = (top << 8) + aexpr->bytes[pc++];
1183           break;
1184
1185         case gdb_agent_op_reg:
1186           /* Flush the cached stack top.  */
1187           stack[sp++] = top;
1188           arg = aexpr->bytes[pc++];
1189           arg = (arg << 8) + aexpr->bytes[pc++];
1190           {
1191             int regnum = arg;
1192             struct regcache *regcache = ctx->regcache;
1193
1194             switch (register_size (regcache->tdesc, regnum))
1195               {
1196               case 8:
1197                 collect_register (regcache, regnum, cnv.u64.bytes);
1198                 top = cnv.u64.val;
1199                 break;
1200               case 4:
1201                 collect_register (regcache, regnum, cnv.u32.bytes);
1202                 top = cnv.u32.val;
1203                 break;
1204               case 2:
1205                 collect_register (regcache, regnum, cnv.u16.bytes);
1206                 top = cnv.u16.val;
1207                 break;
1208               case 1:
1209                 collect_register (regcache, regnum, cnv.u8.bytes);
1210                 top = cnv.u8.val;
1211                 break;
1212               default:
1213                 internal_error (__FILE__, __LINE__,
1214                                 "unhandled register size");
1215               }
1216           }
1217           break;
1218
1219         case gdb_agent_op_end:
1220           ax_debug ("At end of expression, sp=%d, stack top cache=0x%s",
1221                     sp, pulongest (top));
1222           if (rslt)
1223             {
1224               if (sp <= 0)
1225                 {
1226                   /* This should be an error */
1227                   ax_debug ("Stack is empty, nothing to return");
1228                   return expr_eval_empty_stack;
1229                 }
1230               *rslt = top;
1231             }
1232           return expr_eval_no_error;
1233
1234         case gdb_agent_op_dup:
1235           stack[sp++] = top;
1236           break;
1237
1238         case gdb_agent_op_pop:
1239           if (--sp >= 0)
1240             top = stack[sp];
1241           break;
1242
1243         case gdb_agent_op_pick:
1244           arg = aexpr->bytes[pc++];
1245           stack[sp] = top;
1246           top = stack[sp - arg];
1247           ++sp;
1248           break;
1249
1250         case gdb_agent_op_rot:
1251           {
1252             ULONGEST tem = stack[sp - 1];
1253
1254             stack[sp - 1] = stack[sp - 2];
1255             stack[sp - 2] = top;
1256             top = tem;
1257           }
1258           break;
1259
1260         case gdb_agent_op_zero_ext:
1261           arg = aexpr->bytes[pc++];
1262           if (arg < (sizeof (LONGEST) * 8))
1263             top &= ((LONGEST) 1 << arg) - 1;
1264           break;
1265
1266         case gdb_agent_op_swap:
1267           /* Interchange top two stack elements, making sure top gets
1268              copied back onto stack.  */
1269           stack[sp] = top;
1270           top = stack[sp - 1];
1271           stack[sp - 1] = stack[sp];
1272           break;
1273
1274         case gdb_agent_op_getv:
1275           /* Flush the cached stack top.  */
1276           stack[sp++] = top;
1277           arg = aexpr->bytes[pc++];
1278           arg = (arg << 8) + aexpr->bytes[pc++];
1279           top = agent_get_trace_state_variable_value (arg);
1280           break;
1281
1282         case gdb_agent_op_setv:
1283           arg = aexpr->bytes[pc++];
1284           arg = (arg << 8) + aexpr->bytes[pc++];
1285           agent_set_trace_state_variable_value (arg, top);
1286           /* Note that we leave the value on the stack, for the
1287              benefit of later/enclosing expressions.  */
1288           break;
1289
1290         case gdb_agent_op_tracev:
1291           arg = aexpr->bytes[pc++];
1292           arg = (arg << 8) + aexpr->bytes[pc++];
1293           agent_tsv_read (ctx, arg);
1294           break;
1295
1296         case gdb_agent_op_tracenz:
1297           agent_mem_read_string (ctx, NULL, (CORE_ADDR) stack[--sp],
1298                                  (ULONGEST) top);
1299           if (--sp >= 0)
1300             top = stack[sp];
1301           break;
1302
1303         case gdb_agent_op_printf:
1304           {
1305             int nargs, slen, i;
1306             CORE_ADDR fn = 0, chan = 0;
1307             /* Can't have more args than the entire size of the stack.  */
1308             ULONGEST args[STACK_MAX];
1309             char *format;
1310
1311             nargs = aexpr->bytes[pc++];
1312             slen = aexpr->bytes[pc++];
1313             slen = (slen << 8) + aexpr->bytes[pc++];
1314             format = (char *) &(aexpr->bytes[pc]);
1315             pc += slen;
1316             /* Pop function and channel.  */
1317             fn = top;
1318             if (--sp >= 0)
1319               top = stack[sp];
1320             chan = top;
1321             if (--sp >= 0)
1322               top = stack[sp];
1323             /* Pop arguments into a dedicated array.  */
1324             for (i = 0; i < nargs; ++i)
1325               {
1326                 args[i] = top;
1327                 if (--sp >= 0)
1328                   top = stack[sp];
1329               }
1330
1331             /* A bad format string means something is very wrong; give
1332                up immediately.  */
1333             if (format[slen - 1] != '\0')
1334               error (_("Unterminated format string in printf bytecode"));
1335
1336             ax_printf (fn, chan, format, nargs, args);
1337           }
1338           break;
1339
1340           /* GDB never (currently) generates any of these ops.  */
1341         case gdb_agent_op_float:
1342         case gdb_agent_op_ref_float:
1343         case gdb_agent_op_ref_double:
1344         case gdb_agent_op_ref_long_double:
1345         case gdb_agent_op_l_to_d:
1346         case gdb_agent_op_d_to_l:
1347         case gdb_agent_op_trace16:
1348           ax_debug ("Agent expression op 0x%x valid, but not handled",
1349                     op);
1350           /* If ever GDB generates any of these, we don't have the
1351              option of ignoring.  */
1352           return expr_eval_unhandled_opcode;
1353
1354         default:
1355           ax_debug ("Agent expression op 0x%x not recognized", op);
1356           /* Don't struggle on, things will just get worse.  */
1357           return expr_eval_unrecognized_opcode;
1358         }
1359
1360       /* Check for stack badness.  */
1361       if (sp >= (STACK_MAX - 1))
1362         {
1363           ax_debug ("Expression stack overflow");
1364           return expr_eval_stack_overflow;
1365         }
1366
1367       if (sp < 0)
1368         {
1369           ax_debug ("Expression stack underflow");
1370           return expr_eval_stack_underflow;
1371         }
1372
1373       ax_debug ("Op %s -> sp=%d, top=0x%s",
1374                 gdb_agent_op_name (op), sp, phex_nz (top, 0));
1375     }
1376 }