gdb/lm32-tdep.c

   1 /* Target-dependent code for Lattice Mico32 processor, for GDB.
   2    Contributed by Jon Beniston <jon@beniston.com>
   3
   4    Copyright (C) 2009-2020 Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22 #include "frame.h"
  23 #include "frame-unwind.h"
  24 #include "frame-base.h"
  25 #include "inferior.h"
  26 #include "dis-asm.h"
  27 #include "symfile.h"
  28 #include "remote.h"
  29 #include "gdbcore.h"
  30 #include "gdb/sim-lm32.h"
  31 #include "gdb/callback.h"
  32 #include "gdb/remote-sim.h"
  33 #include "sim-regno.h"
  34 #include "arch-utils.h"
  35 #include "regcache.h"
  36 #include "trad-frame.h"
  37 #include "reggroups.h"
  38 #include "opcodes/lm32-desc.h"
  39 #include <algorithm>
  40
  41 /* Macros to extract fields from an instruction.  */
  42 #define LM32_OPCODE(insn)       ((insn >> 26) & 0x3f)
  43 #define LM32_REG0(insn)         ((insn >> 21) & 0x1f)
  44 #define LM32_REG1(insn)         ((insn >> 16) & 0x1f)
  45 #define LM32_REG2(insn)         ((insn >> 11) & 0x1f)
  46 #define LM32_IMM16(insn)        ((((long)insn & 0xffff) << 16) >> 16)
  47
  48 struct gdbarch_tdep
  49 {
  50   /* gdbarch target dependent data here.  Currently unused for LM32.  */
  51 };
  52
  53 struct lm32_frame_cache
  54 {
  55   /* The frame's base.  Used when constructing a frame ID.  */
  56   CORE_ADDR base;
  57   CORE_ADDR pc;
  58   /* Size of frame.  */
  59   int size;
  60   /* Table indicating the location of each and every register.  */
  61   struct trad_frame_saved_reg *saved_regs;
  62 };
  63
  64 /* Add the available register groups.  */
  65
  66 static void
  67 lm32_add_reggroups (struct gdbarch *gdbarch)
  68 {
  69   reggroup_add (gdbarch, general_reggroup);
  70   reggroup_add (gdbarch, all_reggroup);
  71   reggroup_add (gdbarch, system_reggroup);
  72 }
  73
  74 /* Return whether a given register is in a given group.  */
  75
  76 static int
  77 lm32_register_reggroup_p (struct gdbarch *gdbarch, int regnum,
  78                           struct reggroup *group)
  79 {
  80   if (group == general_reggroup)
  81     return ((regnum >= SIM_LM32_R0_REGNUM) && (regnum <= SIM_LM32_RA_REGNUM))
  82       || (regnum == SIM_LM32_PC_REGNUM);
  83   else if (group == system_reggroup)
  84     return ((regnum >= SIM_LM32_EA_REGNUM) && (regnum <= SIM_LM32_BA_REGNUM))
  85       || ((regnum >= SIM_LM32_EID_REGNUM) && (regnum <= SIM_LM32_IP_REGNUM));
  86   return default_register_reggroup_p (gdbarch, regnum, group);
  87 }
  88
  89 /* Return a name that corresponds to the given register number.  */
  90
  91 static const char *
  92 lm32_register_name (struct gdbarch *gdbarch, int reg_nr)
  93 {
  94   static const char *register_names[] = {
  95     "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
  96     "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
  97     "r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23",
  98     "r24", "r25", "gp", "fp", "sp", "ra", "ea", "ba",
  99     "PC", "EID", "EBA", "DEBA", "IE", "IM", "IP"
 100   };
 101
 102   if ((reg_nr < 0) || (reg_nr >= ARRAY_SIZE (register_names)))
 103     return NULL;
 104   else
 105     return register_names[reg_nr];
 106 }
 107
 108 /* Return type of register.  */
 109
 110 static struct type *
 111 lm32_register_type (struct gdbarch *gdbarch, int reg_nr)
 112 {
 113   return builtin_type (gdbarch)->builtin_int32;
 114 }
 115
 116 /* Return non-zero if a register can't be written.  */
 117
 118 static int
 119 lm32_cannot_store_register (struct gdbarch *gdbarch, int regno)
 120 {
 121   return (regno == SIM_LM32_R0_REGNUM) || (regno == SIM_LM32_EID_REGNUM);
 122 }
 123
 124 /* Analyze a function's prologue.  */
 125
 126 static CORE_ADDR
 127 lm32_analyze_prologue (struct gdbarch *gdbarch,
 128                        CORE_ADDR pc, CORE_ADDR limit,
 129                        struct lm32_frame_cache *info)
 130 {
 131   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 132   unsigned long instruction;
 133
 134   /* Keep reading though instructions, until we come across an instruction
 135      that isn't likely to be part of the prologue.  */
 136   info->size = 0;
 137   for (; pc < limit; pc += 4)
 138     {
 139
 140       /* Read an instruction.  */
 141       instruction = read_memory_integer (pc, 4, byte_order);
 142
 143       if ((LM32_OPCODE (instruction) == OP_SW)
 144           && (LM32_REG0 (instruction) == SIM_LM32_SP_REGNUM))
 145         {
 146           /* Any stack displaced store is likely part of the prologue.
 147              Record that the register is being saved, and the offset
 148              into the stack.  */
 149           info->saved_regs[LM32_REG1 (instruction)].addr =
 150             LM32_IMM16 (instruction);
 151         }
 152       else if ((LM32_OPCODE (instruction) == OP_ADDI)
 153                && (LM32_REG1 (instruction) == SIM_LM32_SP_REGNUM))
 154         {
 155           /* An add to the SP is likely to be part of the prologue.
 156              Adjust stack size by whatever the instruction adds to the sp.  */
 157           info->size -= LM32_IMM16 (instruction);
 158         }
 159       else if (                 /* add fp,fp,sp */
 160                 ((LM32_OPCODE (instruction) == OP_ADD)
 161                  && (LM32_REG2 (instruction) == SIM_LM32_FP_REGNUM)
 162                  && (LM32_REG0 (instruction) == SIM_LM32_FP_REGNUM)
 163                  && (LM32_REG1 (instruction) == SIM_LM32_SP_REGNUM))
 164                 /* mv fp,imm */
 165                 || ((LM32_OPCODE (instruction) == OP_ADDI)
 166                     && (LM32_REG1 (instruction) == SIM_LM32_FP_REGNUM)
 167                     && (LM32_REG0 (instruction) == SIM_LM32_R0_REGNUM)))
 168         {
 169           /* Likely to be in the prologue for functions that require
 170              a frame pointer.  */
 171         }
 172       else
 173         {
 174           /* Any other instruction is likely not to be part of the
 175              prologue.  */
 176           break;
 177         }
 178     }
 179
 180   return pc;
 181 }
 182
 183 /* Return PC of first non prologue instruction, for the function at the
 184    specified address.  */
 185
 186 static CORE_ADDR
 187 lm32_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
 188 {
 189   CORE_ADDR func_addr, limit_pc;
 190   struct lm32_frame_cache frame_info;
 191   struct trad_frame_saved_reg saved_regs[SIM_LM32_NUM_REGS];
 192
 193   /* See if we can determine the end of the prologue via the symbol table.
 194      If so, then return either PC, or the PC after the prologue, whichever
 195      is greater.  */
 196   if (find_pc_partial_function (pc, NULL, &func_addr, NULL))
 197     {
 198       CORE_ADDR post_prologue_pc
 199         = skip_prologue_using_sal (gdbarch, func_addr);
 200       if (post_prologue_pc != 0)
 201         return std::max (pc, post_prologue_pc);
 202     }
 203
 204   /* Can't determine prologue from the symbol table, need to examine
 205      instructions.  */
 206
 207   /* Find an upper limit on the function prologue using the debug
 208      information.  If the debug information could not be used to provide
 209      that bound, then use an arbitrary large number as the upper bound.  */
 210   limit_pc = skip_prologue_using_sal (gdbarch, pc);
 211   if (limit_pc == 0)
 212     limit_pc = pc + 100;        /* Magic.  */
 213
 214   frame_info.saved_regs = saved_regs;
 215   return lm32_analyze_prologue (gdbarch, pc, limit_pc, &frame_info);
 216 }
 217
 218 /* Create a breakpoint instruction.  */
 219 constexpr gdb_byte lm32_break_insn[4] = { OP_RAISE << 2, 0, 0, 2 };
 220
 221 typedef BP_MANIPULATION (lm32_break_insn) lm32_breakpoint;
 222
 223
 224 /* Setup registers and stack for faking a call to a function in the
 225    inferior.  */
 226
 227 static CORE_ADDR
 228 lm32_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
 229                       struct regcache *regcache, CORE_ADDR bp_addr,
 230                       int nargs, struct value **args, CORE_ADDR sp,
 231                       function_call_return_method return_method,
 232                       CORE_ADDR struct_addr)
 233 {
 234   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 235   int first_arg_reg = SIM_LM32_R1_REGNUM;
 236   int num_arg_regs = 8;
 237   int i;
 238
 239   /* Set the return address.  */
 240   regcache_cooked_write_signed (regcache, SIM_LM32_RA_REGNUM, bp_addr);
 241
 242   /* If we're returning a large struct, a pointer to the address to
 243      store it at is passed as a first hidden parameter.  */
 244   if (return_method == return_method_struct)
 245     {
 246       regcache_cooked_write_unsigned (regcache, first_arg_reg, struct_addr);
 247       first_arg_reg++;
 248       num_arg_regs--;
 249       sp -= 4;
 250     }
 251
 252   /* Setup parameters.  */
 253   for (i = 0; i < nargs; i++)
 254     {
 255       struct value *arg = args[i];
 256       struct type *arg_type = check_typedef (value_type (arg));
 257       gdb_byte *contents;
 258       ULONGEST val;
 259
 260       /* Promote small integer types to int.  */
 261       switch (TYPE_CODE (arg_type))
 262         {
 263         case TYPE_CODE_INT:
 264         case TYPE_CODE_BOOL:
 265         case TYPE_CODE_CHAR:
 266         case TYPE_CODE_RANGE:
 267         case TYPE_CODE_ENUM:
 268           if (TYPE_LENGTH (arg_type) < 4)
 269             {
 270               arg_type = builtin_type (gdbarch)->builtin_int32;
 271               arg = value_cast (arg_type, arg);
 272             }
 273           break;
 274         }
 275
 276       /* FIXME: Handle structures.  */
 277
 278       contents = (gdb_byte *) value_contents (arg);
 279       val = extract_unsigned_integer (contents, TYPE_LENGTH (arg_type),
 280                                       byte_order);
 281
 282       /* First num_arg_regs parameters are passed by registers,
 283          and the rest are passed on the stack.  */
 284       if (i < num_arg_regs)
 285         regcache_cooked_write_unsigned (regcache, first_arg_reg + i, val);
 286       else
 287         {
 288           write_memory_unsigned_integer (sp, TYPE_LENGTH (arg_type), byte_order,
 289                                          val);
 290           sp -= 4;
 291         }
 292     }
 293
 294   /* Update stack pointer.  */
 295   regcache_cooked_write_signed (regcache, SIM_LM32_SP_REGNUM, sp);
 296
 297   /* Return adjusted stack pointer.  */
 298   return sp;
 299 }
 300
 301 /* Extract return value after calling a function in the inferior.  */
 302
 303 static void
 304 lm32_extract_return_value (struct type *type, struct regcache *regcache,
 305                            gdb_byte *valbuf)
 306 {
 307   struct gdbarch *gdbarch = regcache->arch ();
 308   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 309   ULONGEST l;
 310   CORE_ADDR return_buffer;
 311
 312   if (TYPE_CODE (type) != TYPE_CODE_STRUCT
 313       && TYPE_CODE (type) != TYPE_CODE_UNION
 314       && TYPE_CODE (type) != TYPE_CODE_ARRAY && TYPE_LENGTH (type) <= 4)
 315     {
 316       /* Return value is returned in a single register.  */
 317       regcache_cooked_read_unsigned (regcache, SIM_LM32_R1_REGNUM, &l);
 318       store_unsigned_integer (valbuf, TYPE_LENGTH (type), byte_order, l);
 319     }
 320   else if ((TYPE_CODE (type) == TYPE_CODE_INT) && (TYPE_LENGTH (type) == 8))
 321     {
 322       /* 64-bit values are returned in a register pair.  */
 323       regcache_cooked_read_unsigned (regcache, SIM_LM32_R1_REGNUM, &l);
 324       memcpy (valbuf, &l, 4);
 325       regcache_cooked_read_unsigned (regcache, SIM_LM32_R2_REGNUM, &l);
 326       memcpy (valbuf + 4, &l, 4);
 327     }
 328   else
 329     {
 330       /* Aggregate types greater than a single register are returned
 331          in memory.  FIXME: Unless they are only 2 regs?.  */
 332       regcache_cooked_read_unsigned (regcache, SIM_LM32_R1_REGNUM, &l);
 333       return_buffer = l;
 334       read_memory (return_buffer, valbuf, TYPE_LENGTH (type));
 335     }
 336 }
 337
 338 /* Write into appropriate registers a function return value of type
 339    TYPE, given in virtual format.  */
 340 static void
 341 lm32_store_return_value (struct type *type, struct regcache *regcache,
 342                          const gdb_byte *valbuf)
 343 {
 344   struct gdbarch *gdbarch = regcache->arch ();
 345   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 346   ULONGEST val;
 347   int len = TYPE_LENGTH (type);
 348
 349   if (len <= 4)
 350     {
 351       val = extract_unsigned_integer (valbuf, len, byte_order);
 352       regcache_cooked_write_unsigned (regcache, SIM_LM32_R1_REGNUM, val);
 353     }
 354   else if (len <= 8)
 355     {
 356       val = extract_unsigned_integer (valbuf, 4, byte_order);
 357       regcache_cooked_write_unsigned (regcache, SIM_LM32_R1_REGNUM, val);
 358       val = extract_unsigned_integer (valbuf + 4, len - 4, byte_order);
 359       regcache_cooked_write_unsigned (regcache, SIM_LM32_R2_REGNUM, val);
 360     }
 361   else
 362     error (_("lm32_store_return_value: type length too large."));
 363 }
 364
 365 /* Determine whether a functions return value is in a register or memory.  */
 366 static enum return_value_convention
 367 lm32_return_value (struct gdbarch *gdbarch, struct value *function,
 368                    struct type *valtype, struct regcache *regcache,
 369                    gdb_byte *readbuf, const gdb_byte *writebuf)
 370 {
 371   enum type_code code = TYPE_CODE (valtype);
 372
 373   if (code == TYPE_CODE_STRUCT
 374       || code == TYPE_CODE_UNION
 375       || code == TYPE_CODE_ARRAY || TYPE_LENGTH (valtype) > 8)
 376     return RETURN_VALUE_STRUCT_CONVENTION;
 377
 378   if (readbuf)
 379     lm32_extract_return_value (valtype, regcache, readbuf);
 380   if (writebuf)
 381     lm32_store_return_value (valtype, regcache, writebuf);
 382
 383   return RETURN_VALUE_REGISTER_CONVENTION;
 384 }
 385
 386 /* Put here the code to store, into fi->saved_regs, the addresses of
 387    the saved registers of frame described by FRAME_INFO.  This
 388    includes special registers such as pc and fp saved in special ways
 389    in the stack frame.  sp is even more special: the address we return
 390    for it IS the sp for the next frame.  */
 391
 392 static struct lm32_frame_cache *
 393 lm32_frame_cache (struct frame_info *this_frame, void **this_prologue_cache)
 394 {
 395   CORE_ADDR current_pc;
 396   ULONGEST prev_sp;
 397   ULONGEST this_base;
 398   struct lm32_frame_cache *info;
 399   int i;
 400
 401   if ((*this_prologue_cache))
 402     return (struct lm32_frame_cache *) (*this_prologue_cache);
 403
 404   info = FRAME_OBSTACK_ZALLOC (struct lm32_frame_cache);
 405   (*this_prologue_cache) = info;
 406   info->saved_regs = trad_frame_alloc_saved_regs (this_frame);
 407
 408   info->pc = get_frame_func (this_frame);
 409   current_pc = get_frame_pc (this_frame);
 410   lm32_analyze_prologue (get_frame_arch (this_frame),
 411                          info->pc, current_pc, info);
 412
 413   /* Compute the frame's base, and the previous frame's SP.  */
 414   this_base = get_frame_register_unsigned (this_frame, SIM_LM32_SP_REGNUM);
 415   prev_sp = this_base + info->size;
 416   info->base = this_base;
 417
 418   /* Convert callee save offsets into addresses.  */
 419   for (i = 0; i < gdbarch_num_regs (get_frame_arch (this_frame)) - 1; i++)
 420     {
 421       if (trad_frame_addr_p (info->saved_regs, i))
 422         info->saved_regs[i].addr = this_base + info->saved_regs[i].addr;
 423     }
 424
 425   /* The call instruction moves the caller's PC in the callee's RA register.
 426      Since this is an unwind, do the reverse.  Copy the location of RA register
 427      into PC (the address / regnum) so that a request for PC will be
 428      converted into a request for the RA register.  */
 429   info->saved_regs[SIM_LM32_PC_REGNUM] = info->saved_regs[SIM_LM32_RA_REGNUM];
 430
 431   /* The previous frame's SP needed to be computed.  Save the computed
 432      value.  */
 433   trad_frame_set_value (info->saved_regs, SIM_LM32_SP_REGNUM, prev_sp);
 434
 435   return info;
 436 }
 437
 438 static void
 439 lm32_frame_this_id (struct frame_info *this_frame, void **this_cache,
 440                     struct frame_id *this_id)
 441 {
 442   struct lm32_frame_cache *cache = lm32_frame_cache (this_frame, this_cache);
 443
 444   /* This marks the outermost frame.  */
 445   if (cache->base == 0)
 446     return;
 447
 448   (*this_id) = frame_id_build (cache->base, cache->pc);
 449 }
 450
 451 static struct value *
 452 lm32_frame_prev_register (struct frame_info *this_frame,
 453                           void **this_prologue_cache, int regnum)
 454 {
 455   struct lm32_frame_cache *info;
 456
 457   info = lm32_frame_cache (this_frame, this_prologue_cache);
 458   return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
 459 }
 460
 461 static const struct frame_unwind lm32_frame_unwind = {
 462   NORMAL_FRAME,
 463   default_frame_unwind_stop_reason,
 464   lm32_frame_this_id,
 465   lm32_frame_prev_register,
 466   NULL,
 467   default_frame_sniffer
 468 };
 469
 470 static CORE_ADDR
 471 lm32_frame_base_address (struct frame_info *this_frame, void **this_cache)
 472 {
 473   struct lm32_frame_cache *info = lm32_frame_cache (this_frame, this_cache);
 474
 475   return info->base;
 476 }
 477
 478 static const struct frame_base lm32_frame_base = {
 479   &lm32_frame_unwind,
 480   lm32_frame_base_address,
 481   lm32_frame_base_address,
 482   lm32_frame_base_address
 483 };
 484
 485 static CORE_ADDR
 486 lm32_frame_align (struct gdbarch *gdbarch, CORE_ADDR sp)
 487 {
 488   /* Align to the size of an instruction (so that they can safely be
 489      pushed onto the stack.  */
 490   return sp & ~3;
 491 }
 492
 493 static struct gdbarch *
 494 lm32_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 495 {
 496   struct gdbarch *gdbarch;
 497   struct gdbarch_tdep *tdep;
 498
 499   /* If there is already a candidate, use it.  */
 500   arches = gdbarch_list_lookup_by_info (arches, &info);
 501   if (arches != NULL)
 502     return arches->gdbarch;
 503
 504   /* None found, create a new architecture from the information provided.  */
 505   tdep = XCNEW (struct gdbarch_tdep);
 506   gdbarch = gdbarch_alloc (&info, tdep);
 507
 508   /* Type sizes.  */
 509   set_gdbarch_short_bit (gdbarch, 16);
 510   set_gdbarch_int_bit (gdbarch, 32);
 511   set_gdbarch_long_bit (gdbarch, 32);
 512   set_gdbarch_long_long_bit (gdbarch, 64);
 513   set_gdbarch_float_bit (gdbarch, 32);
 514   set_gdbarch_double_bit (gdbarch, 64);
 515   set_gdbarch_long_double_bit (gdbarch, 64);
 516   set_gdbarch_ptr_bit (gdbarch, 32);
 517
 518   /* Register info.  */
 519   set_gdbarch_num_regs (gdbarch, SIM_LM32_NUM_REGS);
 520   set_gdbarch_sp_regnum (gdbarch, SIM_LM32_SP_REGNUM);
 521   set_gdbarch_pc_regnum (gdbarch, SIM_LM32_PC_REGNUM);
 522   set_gdbarch_register_name (gdbarch, lm32_register_name);
 523   set_gdbarch_register_type (gdbarch, lm32_register_type);
 524   set_gdbarch_cannot_store_register (gdbarch, lm32_cannot_store_register);
 525
 526   /* Frame info.  */
 527   set_gdbarch_skip_prologue (gdbarch, lm32_skip_prologue);
 528   set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
 529   set_gdbarch_decr_pc_after_break (gdbarch, 0);
 530   set_gdbarch_frame_args_skip (gdbarch, 0);
 531
 532   /* Frame unwinding.  */
 533   set_gdbarch_frame_align (gdbarch, lm32_frame_align);
 534   frame_base_set_default (gdbarch, &lm32_frame_base);
 535   frame_unwind_append_unwinder (gdbarch, &lm32_frame_unwind);
 536
 537   /* Breakpoints.  */
 538   set_gdbarch_breakpoint_kind_from_pc (gdbarch, lm32_breakpoint::kind_from_pc);
 539   set_gdbarch_sw_breakpoint_from_kind (gdbarch, lm32_breakpoint::bp_from_kind);
 540   set_gdbarch_have_nonsteppable_watchpoint (gdbarch, 1);
 541
 542   /* Calling functions in the inferior.  */
 543   set_gdbarch_push_dummy_call (gdbarch, lm32_push_dummy_call);
 544   set_gdbarch_return_value (gdbarch, lm32_return_value);
 545
 546   lm32_add_reggroups (gdbarch);
 547   set_gdbarch_register_reggroup_p (gdbarch, lm32_register_reggroup_p);
 548
 549   return gdbarch;
 550 }
 551
 552 void _initialize_lm32_tdep ();
 553 void
 554 _initialize_lm32_tdep ()
 555 {
 556   register_gdbarch_init (bfd_arch_lm32, lm32_gdbarch_init);
 557 }