gdb/vax-tdep.c

   1 /* Target-dependent code for the VAX.
   2
   3    Copyright (C) 1986, 1989, 1991, 1992, 1995, 1996, 1998, 1999, 2000, 2002,
   4    2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011
   5    Free Software Foundation, Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22 #include "defs.h"
  23 #include "arch-utils.h"
  24 #include "dis-asm.h"
  25 #include "floatformat.h"
  26 #include "frame.h"
  27 #include "frame-base.h"
  28 #include "frame-unwind.h"
  29 #include "gdbcore.h"
  30 #include "gdbtypes.h"
  31 #include "osabi.h"
  32 #include "regcache.h"
  33 #include "regset.h"
  34 #include "trad-frame.h"
  35 #include "value.h"
  36
  37 #include "gdb_string.h"
  38
  39 #include "vax-tdep.h"
  40
  41 /* Return the name of register REGNUM.  */
  42
  43 static const char *
  44 vax_register_name (struct gdbarch *gdbarch, int regnum)
  45 {
  46   static char *register_names[] =
  47   {
  48     "r0", "r1", "r2",  "r3",  "r4", "r5", "r6", "r7",
  49     "r8", "r9", "r10", "r11", "ap", "fp", "sp", "pc",
  50     "ps",
  51   };
  52
  53   if (regnum >= 0 && regnum < ARRAY_SIZE (register_names))
  54     return register_names[regnum];
  55
  56   return NULL;
  57 }
  58
  59 /* Return the GDB type object for the "standard" data type of data in
  60    register REGNUM.  */
  61
  62 static struct type *
  63 vax_register_type (struct gdbarch *gdbarch, int regnum)
  64 {
  65   return builtin_type (gdbarch)->builtin_int;
  66 }
  67 \f
  68 /* Core file support.  */
  69
  70 /* Supply register REGNUM from the buffer specified by GREGS and LEN
  71    in the general-purpose register set REGSET to register cache
  72    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  73
  74 static void
  75 vax_supply_gregset (const struct regset *regset, struct regcache *regcache,
  76                     int regnum, const void *gregs, size_t len)
  77 {
  78   const gdb_byte *regs = gregs;
  79   int i;
  80
  81   for (i = 0; i < VAX_NUM_REGS; i++)
  82     {
  83       if (regnum == i || regnum == -1)
  84         regcache_raw_supply (regcache, i, regs + i * 4);
  85     }
  86 }
  87
  88 /* VAX register set.  */
  89
  90 static struct regset vax_gregset =
  91 {
  92   NULL,
  93   vax_supply_gregset
  94 };
  95
  96 /* Return the appropriate register set for the core section identified
  97    by SECT_NAME and SECT_SIZE.  */
  98
  99 static const struct regset *
 100 vax_regset_from_core_section (struct gdbarch *gdbarch,
 101                               const char *sect_name, size_t sect_size)
 102 {
 103   if (strcmp (sect_name, ".reg") == 0 && sect_size >= VAX_NUM_REGS * 4)
 104     return &vax_gregset;
 105
 106   return NULL;
 107 }
 108 \f
 109 /* The VAX UNIX calling convention uses R1 to pass a structure return
 110    value address instead of passing it as a first (hidden) argument as
 111    the VMS calling convention suggests.  */
 112
 113 static CORE_ADDR
 114 vax_store_arguments (struct regcache *regcache, int nargs,
 115                      struct value **args, CORE_ADDR sp)
 116 {
 117   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 118   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 119   gdb_byte buf[4];
 120   int count = 0;
 121   int i;
 122
 123   /* We create an argument list on the stack, and make the argument
 124      pointer to it.  */
 125
 126   /* Push arguments in reverse order.  */
 127   for (i = nargs - 1; i >= 0; i--)
 128     {
 129       int len = TYPE_LENGTH (value_enclosing_type (args[i]));
 130
 131       sp -= (len + 3) & ~3;
 132       count += (len + 3) / 4;
 133       write_memory (sp, value_contents_all (args[i]), len);
 134     }
 135
 136   /* Push argument count.  */
 137   sp -= 4;
 138   store_unsigned_integer (buf, 4, byte_order, count);
 139   write_memory (sp, buf, 4);
 140
 141   /* Update the argument pointer.  */
 142   store_unsigned_integer (buf, 4, byte_order, sp);
 143   regcache_cooked_write (regcache, VAX_AP_REGNUM, buf);
 144
 145   return sp;
 146 }
 147
 148 static CORE_ADDR
 149 vax_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
 150                      struct regcache *regcache, CORE_ADDR bp_addr, int nargs,
 151                      struct value **args, CORE_ADDR sp, int struct_return,
 152                      CORE_ADDR struct_addr)
 153 {
 154   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 155   CORE_ADDR fp = sp;
 156   gdb_byte buf[4];
 157
 158   /* Set up the function arguments.  */
 159   sp = vax_store_arguments (regcache, nargs, args, sp);
 160
 161   /* Store return value address.  */
 162   if (struct_return)
 163     regcache_cooked_write_unsigned (regcache, VAX_R1_REGNUM, struct_addr);
 164
 165   /* Store return address in the PC slot.  */
 166   sp -= 4;
 167   store_unsigned_integer (buf, 4, byte_order, bp_addr);
 168   write_memory (sp, buf, 4);
 169
 170   /* Store the (fake) frame pointer in the FP slot.  */
 171   sp -= 4;
 172   store_unsigned_integer (buf, 4, byte_order, fp);
 173   write_memory (sp, buf, 4);
 174
 175   /* Skip the AP slot.  */
 176   sp -= 4;
 177
 178   /* Store register save mask and control bits.  */
 179   sp -= 4;
 180   store_unsigned_integer (buf, 4, byte_order, 0);
 181   write_memory (sp, buf, 4);
 182
 183   /* Store condition handler.  */
 184   sp -= 4;
 185   store_unsigned_integer (buf, 4, byte_order, 0);
 186   write_memory (sp, buf, 4);
 187
 188   /* Update the stack pointer and frame pointer.  */
 189   store_unsigned_integer (buf, 4, byte_order, sp);
 190   regcache_cooked_write (regcache, VAX_SP_REGNUM, buf);
 191   regcache_cooked_write (regcache, VAX_FP_REGNUM, buf);
 192
 193   /* Return the saved (fake) frame pointer.  */
 194   return fp;
 195 }
 196
 197 static struct frame_id
 198 vax_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
 199 {
 200   CORE_ADDR fp;
 201
 202   fp = get_frame_register_unsigned (this_frame, VAX_FP_REGNUM);
 203   return frame_id_build (fp, get_frame_pc (this_frame));
 204 }
 205 \f
 206
 207 static enum return_value_convention
 208 vax_return_value (struct gdbarch *gdbarch, struct type *func_type,
 209                   struct type *type, struct regcache *regcache,
 210                   gdb_byte *readbuf, const gdb_byte *writebuf)
 211 {
 212   int len = TYPE_LENGTH (type);
 213   gdb_byte buf[8];
 214
 215   if (TYPE_CODE (type) == TYPE_CODE_STRUCT
 216       || TYPE_CODE (type) == TYPE_CODE_UNION
 217       || TYPE_CODE (type) == TYPE_CODE_ARRAY)
 218     {
 219       /* The default on VAX is to return structures in static memory.
 220          Consequently a function must return the address where we can
 221          find the return value.  */
 222
 223       if (readbuf)
 224         {
 225           ULONGEST addr;
 226
 227           regcache_raw_read_unsigned (regcache, VAX_R0_REGNUM, &addr);
 228           read_memory (addr, readbuf, len);
 229         }
 230
 231       return RETURN_VALUE_ABI_RETURNS_ADDRESS;
 232     }
 233
 234   if (readbuf)
 235     {
 236       /* Read the contents of R0 and (if necessary) R1.  */
 237       regcache_cooked_read (regcache, VAX_R0_REGNUM, buf);
 238       if (len > 4)
 239         regcache_cooked_read (regcache, VAX_R1_REGNUM, buf + 4);
 240       memcpy (readbuf, buf, len);
 241     }
 242   if (writebuf)
 243     {
 244       /* Read the contents to R0 and (if necessary) R1.  */
 245       memcpy (buf, writebuf, len);
 246       regcache_cooked_write (regcache, VAX_R0_REGNUM, buf);
 247       if (len > 4)
 248         regcache_cooked_write (regcache, VAX_R1_REGNUM, buf + 4);
 249     }
 250
 251   return RETURN_VALUE_REGISTER_CONVENTION;
 252 }
 253 \f
 254
 255 /* Use the program counter to determine the contents and size of a
 256    breakpoint instruction.  Return a pointer to a string of bytes that
 257    encode a breakpoint instruction, store the length of the string in
 258    *LEN and optionally adjust *PC to point to the correct memory
 259    location for inserting the breakpoint.  */
 260
 261 static const gdb_byte *
 262 vax_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pc, int *len)
 263 {
 264   static gdb_byte break_insn[] = { 3 };
 265
 266   *len = sizeof (break_insn);
 267   return break_insn;
 268 }
 269 \f
 270 /* Advance PC across any function entry prologue instructions
 271    to reach some "real" code.  */
 272
 273 static CORE_ADDR
 274 vax_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
 275 {
 276   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 277   gdb_byte op = read_memory_unsigned_integer (pc, 1, byte_order);
 278
 279   if (op == 0x11)
 280     pc += 2;                    /* skip brb */
 281   if (op == 0x31)
 282     pc += 3;                    /* skip brw */
 283   if (op == 0xC2
 284       && read_memory_unsigned_integer (pc + 2, 1, byte_order) == 0x5E)
 285     pc += 3;                    /* skip subl2 */
 286   if (op == 0x9E
 287       && read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xAE
 288       && read_memory_unsigned_integer (pc + 3, 1, byte_order) == 0x5E)
 289     pc += 4;                    /* skip movab */
 290   if (op == 0x9E
 291       && read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xCE
 292       && read_memory_unsigned_integer (pc + 4, 1, byte_order) == 0x5E)
 293     pc += 5;                    /* skip movab */
 294   if (op == 0x9E
 295       && read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xEE
 296       && read_memory_unsigned_integer (pc + 6, 1, byte_order) == 0x5E)
 297     pc += 7;                    /* skip movab */
 298
 299   return pc;
 300 }
 301 \f
 302
 303 /* Unwinding the stack is relatively easy since the VAX has a
 304    dedicated frame pointer, and frames are set up automatically as the
 305    result of a function call.  Most of the relevant information can be
 306    inferred from the documentation of the Procedure Call Instructions
 307    in the VAX MACRO and Instruction Set Reference Manual.  */
 308
 309 struct vax_frame_cache
 310 {
 311   /* Base address.  */
 312   CORE_ADDR base;
 313
 314   /* Table of saved registers.  */
 315   struct trad_frame_saved_reg *saved_regs;
 316 };
 317
 318 static struct vax_frame_cache *
 319 vax_frame_cache (struct frame_info *this_frame, void **this_cache)
 320 {
 321   struct vax_frame_cache *cache;
 322   CORE_ADDR addr;
 323   ULONGEST mask;
 324   int regnum;
 325
 326   if (*this_cache)
 327     return *this_cache;
 328
 329   /* Allocate a new cache.  */
 330   cache = FRAME_OBSTACK_ZALLOC (struct vax_frame_cache);
 331   cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);
 332
 333   /* The frame pointer is used as the base for the frame.  */
 334   cache->base = get_frame_register_unsigned (this_frame, VAX_FP_REGNUM);
 335   if (cache->base == 0)
 336     return cache;
 337
 338   /* The register save mask and control bits determine the layout of
 339      the stack frame.  */
 340   mask = get_frame_memory_unsigned (this_frame, cache->base + 4, 4) >> 16;
 341
 342   /* These are always saved.  */
 343   cache->saved_regs[VAX_PC_REGNUM].addr = cache->base + 16;
 344   cache->saved_regs[VAX_FP_REGNUM].addr = cache->base + 12;
 345   cache->saved_regs[VAX_AP_REGNUM].addr = cache->base + 8;
 346   cache->saved_regs[VAX_PS_REGNUM].addr = cache->base + 4;
 347
 348   /* Scan the register save mask and record the location of the saved
 349      registers.  */
 350   addr = cache->base + 20;
 351   for (regnum = 0; regnum < VAX_AP_REGNUM; regnum++)
 352     {
 353       if (mask & (1 << regnum))
 354         {
 355           cache->saved_regs[regnum].addr = addr;
 356           addr += 4;
 357         }
 358     }
 359
 360   /* The CALLS/CALLG flag determines whether this frame has a General
 361      Argument List or a Stack Argument List.  */
 362   if (mask & (1 << 13))
 363     {
 364       ULONGEST numarg;
 365
 366       /* This is a procedure with Stack Argument List.  Adjust the
 367          stack address for the arguments that were pushed onto the
 368          stack.  The return instruction will automatically pop the
 369          arguments from the stack.  */
 370       numarg = get_frame_memory_unsigned (this_frame, addr, 1);
 371       addr += 4 + numarg * 4;
 372     }
 373
 374   /* Bits 1:0 of the stack pointer were saved in the control bits.  */
 375   trad_frame_set_value (cache->saved_regs, VAX_SP_REGNUM, addr + (mask >> 14));
 376
 377   return cache;
 378 }
 379
 380 static void
 381 vax_frame_this_id (struct frame_info *this_frame, void **this_cache,
 382                    struct frame_id *this_id)
 383 {
 384   struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);
 385
 386   /* This marks the outermost frame.  */
 387   if (cache->base == 0)
 388     return;
 389
 390   (*this_id) = frame_id_build (cache->base, get_frame_func (this_frame));
 391 }
 392
 393 static struct value *
 394 vax_frame_prev_register (struct frame_info *this_frame,
 395                          void **this_cache, int regnum)
 396 {
 397   struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);
 398
 399   return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum);
 400 }
 401
 402 static const struct frame_unwind vax_frame_unwind =
 403 {
 404   NORMAL_FRAME,
 405   vax_frame_this_id,
 406   vax_frame_prev_register,
 407   NULL,
 408   default_frame_sniffer
 409 };
 410 \f
 411
 412 static CORE_ADDR
 413 vax_frame_base_address (struct frame_info *this_frame, void **this_cache)
 414 {
 415   struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);
 416
 417   return cache->base;
 418 }
 419
 420 static CORE_ADDR
 421 vax_frame_args_address (struct frame_info *this_frame, void **this_cache)
 422 {
 423   return get_frame_register_unsigned (this_frame, VAX_AP_REGNUM);
 424 }
 425
 426 static const struct frame_base vax_frame_base =
 427 {
 428   &vax_frame_unwind,
 429   vax_frame_base_address,
 430   vax_frame_base_address,
 431   vax_frame_args_address
 432 };
 433
 434 /* Return number of arguments for FRAME.  */
 435
 436 static int
 437 vax_frame_num_args (struct frame_info *frame)
 438 {
 439   CORE_ADDR args;
 440
 441   /* Assume that the argument pointer for the outermost frame is
 442      hosed, as is the case on NetBSD/vax ELF.  */
 443   if (get_frame_base_address (frame) == 0)
 444     return 0;
 445
 446   args = get_frame_register_unsigned (frame, VAX_AP_REGNUM);
 447   return get_frame_memory_unsigned (frame, args, 1);
 448 }
 449
 450 static CORE_ADDR
 451 vax_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
 452 {
 453   return frame_unwind_register_unsigned (next_frame, VAX_PC_REGNUM);
 454 }
 455 \f
 456
 457 /* Initialize the current architecture based on INFO.  If possible, re-use an
 458    architecture from ARCHES, which is a list of architectures already created
 459    during this debugging session.
 460
 461    Called e.g. at program startup, when reading a core file, and when reading
 462    a binary file.  */
 463
 464 static struct gdbarch *
 465 vax_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 466 {
 467   struct gdbarch *gdbarch;
 468
 469   /* If there is already a candidate, use it.  */
 470   arches = gdbarch_list_lookup_by_info (arches, &info);
 471   if (arches != NULL)
 472     return arches->gdbarch;
 473
 474   gdbarch = gdbarch_alloc (&info, NULL);
 475
 476   set_gdbarch_float_format (gdbarch, floatformats_vax_f);
 477   set_gdbarch_double_format (gdbarch, floatformats_vax_d);
 478   set_gdbarch_long_double_format (gdbarch, floatformats_vax_d);
 479   set_gdbarch_long_double_bit (gdbarch, 64);
 480
 481   /* Register info */
 482   set_gdbarch_num_regs (gdbarch, VAX_NUM_REGS);
 483   set_gdbarch_register_name (gdbarch, vax_register_name);
 484   set_gdbarch_register_type (gdbarch, vax_register_type);
 485   set_gdbarch_sp_regnum (gdbarch, VAX_SP_REGNUM);
 486   set_gdbarch_pc_regnum (gdbarch, VAX_PC_REGNUM);
 487   set_gdbarch_ps_regnum (gdbarch, VAX_PS_REGNUM);
 488
 489   set_gdbarch_regset_from_core_section
 490     (gdbarch, vax_regset_from_core_section);
 491
 492   /* Frame and stack info */
 493   set_gdbarch_skip_prologue (gdbarch, vax_skip_prologue);
 494   set_gdbarch_frame_num_args (gdbarch, vax_frame_num_args);
 495   set_gdbarch_frame_args_skip (gdbarch, 4);
 496
 497   /* Stack grows downward.  */
 498   set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
 499
 500   /* Return value info */
 501   set_gdbarch_return_value (gdbarch, vax_return_value);
 502
 503   /* Call dummy code.  */
 504   set_gdbarch_push_dummy_call (gdbarch, vax_push_dummy_call);
 505   set_gdbarch_dummy_id (gdbarch, vax_dummy_id);
 506
 507   /* Breakpoint info */
 508   set_gdbarch_breakpoint_from_pc (gdbarch, vax_breakpoint_from_pc);
 509
 510   /* Misc info */
 511   set_gdbarch_deprecated_function_start_offset (gdbarch, 2);
 512   set_gdbarch_believe_pcc_promotion (gdbarch, 1);
 513
 514   set_gdbarch_print_insn (gdbarch, print_insn_vax);
 515
 516   set_gdbarch_unwind_pc (gdbarch, vax_unwind_pc);
 517
 518   frame_base_set_default (gdbarch, &vax_frame_base);
 519
 520   /* Hook in ABI-specific overrides, if they have been registered.  */
 521   gdbarch_init_osabi (info, gdbarch);
 522
 523   frame_unwind_append_unwinder (gdbarch, &vax_frame_unwind);
 524
 525   return (gdbarch);
 526 }
 527
 528 /* Provide a prototype to silence -Wmissing-prototypes.  */
 529 void _initialize_vax_tdep (void);
 530
 531 void
 532 _initialize_vax_tdep (void)
 533 {
 534   gdbarch_register (bfd_arch_vax, vax_gdbarch_init, NULL);
 535 }