gdb/vax-tdep.c

   1 /* Target-dependent code for the VAX.
   2
   3    Copyright (C) 1986-2016 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "arch-utils.h"
  22 #include "dis-asm.h"
  23 #include "floatformat.h"
  24 #include "frame.h"
  25 #include "frame-base.h"
  26 #include "frame-unwind.h"
  27 #include "gdbcore.h"
  28 #include "gdbtypes.h"
  29 #include "osabi.h"
  30 #include "regcache.h"
  31 #include "regset.h"
  32 #include "trad-frame.h"
  33 #include "value.h"
  34
  35 #include "vax-tdep.h"
  36
  37 /* Return the name of register REGNUM.  */
  38
  39 static const char *
  40 vax_register_name (struct gdbarch *gdbarch, int regnum)
  41 {
  42   static char *register_names[] =
  43   {
  44     "r0", "r1", "r2",  "r3",  "r4", "r5", "r6", "r7",
  45     "r8", "r9", "r10", "r11", "ap", "fp", "sp", "pc",
  46     "ps",
  47   };
  48
  49   if (regnum >= 0 && regnum < ARRAY_SIZE (register_names))
  50     return register_names[regnum];
  51
  52   return NULL;
  53 }
  54
  55 /* Return the GDB type object for the "standard" data type of data in
  56    register REGNUM.  */
  57
  58 static struct type *
  59 vax_register_type (struct gdbarch *gdbarch, int regnum)
  60 {
  61   return builtin_type (gdbarch)->builtin_int;
  62 }
  63 \f
  64 /* Core file support.  */
  65
  66 /* Supply register REGNUM from the buffer specified by GREGS and LEN
  67    in the general-purpose register set REGSET to register cache
  68    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  69
  70 static void
  71 vax_supply_gregset (const struct regset *regset, struct regcache *regcache,
  72                     int regnum, const void *gregs, size_t len)
  73 {
  74   const gdb_byte *regs = (const gdb_byte *) gregs;
  75   int i;
  76
  77   for (i = 0; i < VAX_NUM_REGS; i++)
  78     {
  79       if (regnum == i || regnum == -1)
  80         regcache_raw_supply (regcache, i, regs + i * 4);
  81     }
  82 }
  83
  84 /* VAX register set.  */
  85
  86 static const struct regset vax_gregset =
  87 {
  88   NULL,
  89   vax_supply_gregset
  90 };
  91
  92 /* Iterate over core file register note sections.  */
  93
  94 static void
  95 vax_iterate_over_regset_sections (struct gdbarch *gdbarch,
  96                                   iterate_over_regset_sections_cb *cb,
  97                                   void *cb_data,
  98                                   const struct regcache *regcache)
  99 {
 100   cb (".reg", VAX_NUM_REGS * 4, &vax_gregset, NULL, cb_data);
 101 }
 102 \f
 103 /* The VAX UNIX calling convention uses R1 to pass a structure return
 104    value address instead of passing it as a first (hidden) argument as
 105    the VMS calling convention suggests.  */
 106
 107 static CORE_ADDR
 108 vax_store_arguments (struct regcache *regcache, int nargs,
 109                      struct value **args, CORE_ADDR sp)
 110 {
 111   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 112   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 113   gdb_byte buf[4];
 114   int count = 0;
 115   int i;
 116
 117   /* We create an argument list on the stack, and make the argument
 118      pointer to it.  */
 119
 120   /* Push arguments in reverse order.  */
 121   for (i = nargs - 1; i >= 0; i--)
 122     {
 123       int len = TYPE_LENGTH (value_enclosing_type (args[i]));
 124
 125       sp -= (len + 3) & ~3;
 126       count += (len + 3) / 4;
 127       write_memory (sp, value_contents_all (args[i]), len);
 128     }
 129
 130   /* Push argument count.  */
 131   sp -= 4;
 132   store_unsigned_integer (buf, 4, byte_order, count);
 133   write_memory (sp, buf, 4);
 134
 135   /* Update the argument pointer.  */
 136   store_unsigned_integer (buf, 4, byte_order, sp);
 137   regcache_cooked_write (regcache, VAX_AP_REGNUM, buf);
 138
 139   return sp;
 140 }
 141
 142 static CORE_ADDR
 143 vax_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
 144                      struct regcache *regcache, CORE_ADDR bp_addr, int nargs,
 145                      struct value **args, CORE_ADDR sp, int struct_return,
 146                      CORE_ADDR struct_addr)
 147 {
 148   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 149   CORE_ADDR fp = sp;
 150   gdb_byte buf[4];
 151
 152   /* Set up the function arguments.  */
 153   sp = vax_store_arguments (regcache, nargs, args, sp);
 154
 155   /* Store return value address.  */
 156   if (struct_return)
 157     regcache_cooked_write_unsigned (regcache, VAX_R1_REGNUM, struct_addr);
 158
 159   /* Store return address in the PC slot.  */
 160   sp -= 4;
 161   store_unsigned_integer (buf, 4, byte_order, bp_addr);
 162   write_memory (sp, buf, 4);
 163
 164   /* Store the (fake) frame pointer in the FP slot.  */
 165   sp -= 4;
 166   store_unsigned_integer (buf, 4, byte_order, fp);
 167   write_memory (sp, buf, 4);
 168
 169   /* Skip the AP slot.  */
 170   sp -= 4;
 171
 172   /* Store register save mask and control bits.  */
 173   sp -= 4;
 174   store_unsigned_integer (buf, 4, byte_order, 0);
 175   write_memory (sp, buf, 4);
 176
 177   /* Store condition handler.  */
 178   sp -= 4;
 179   store_unsigned_integer (buf, 4, byte_order, 0);
 180   write_memory (sp, buf, 4);
 181
 182   /* Update the stack pointer and frame pointer.  */
 183   store_unsigned_integer (buf, 4, byte_order, sp);
 184   regcache_cooked_write (regcache, VAX_SP_REGNUM, buf);
 185   regcache_cooked_write (regcache, VAX_FP_REGNUM, buf);
 186
 187   /* Return the saved (fake) frame pointer.  */
 188   return fp;
 189 }
 190
 191 static struct frame_id
 192 vax_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
 193 {
 194   CORE_ADDR fp;
 195
 196   fp = get_frame_register_unsigned (this_frame, VAX_FP_REGNUM);
 197   return frame_id_build (fp, get_frame_pc (this_frame));
 198 }
 199 \f
 200
 201 static enum return_value_convention
 202 vax_return_value (struct gdbarch *gdbarch, struct value *function,
 203                   struct type *type, struct regcache *regcache,
 204                   gdb_byte *readbuf, const gdb_byte *writebuf)
 205 {
 206   int len = TYPE_LENGTH (type);
 207   gdb_byte buf[8];
 208
 209   if (TYPE_CODE (type) == TYPE_CODE_STRUCT
 210       || TYPE_CODE (type) == TYPE_CODE_UNION
 211       || TYPE_CODE (type) == TYPE_CODE_ARRAY)
 212     {
 213       /* The default on VAX is to return structures in static memory.
 214          Consequently a function must return the address where we can
 215          find the return value.  */
 216
 217       if (readbuf)
 218         {
 219           ULONGEST addr;
 220
 221           regcache_raw_read_unsigned (regcache, VAX_R0_REGNUM, &addr);
 222           read_memory (addr, readbuf, len);
 223         }
 224
 225       return RETURN_VALUE_ABI_RETURNS_ADDRESS;
 226     }
 227
 228   if (readbuf)
 229     {
 230       /* Read the contents of R0 and (if necessary) R1.  */
 231       regcache_cooked_read (regcache, VAX_R0_REGNUM, buf);
 232       if (len > 4)
 233         regcache_cooked_read (regcache, VAX_R1_REGNUM, buf + 4);
 234       memcpy (readbuf, buf, len);
 235     }
 236   if (writebuf)
 237     {
 238       /* Read the contents to R0 and (if necessary) R1.  */
 239       memcpy (buf, writebuf, len);
 240       regcache_cooked_write (regcache, VAX_R0_REGNUM, buf);
 241       if (len > 4)
 242         regcache_cooked_write (regcache, VAX_R1_REGNUM, buf + 4);
 243     }
 244
 245   return RETURN_VALUE_REGISTER_CONVENTION;
 246 }
 247 \f
 248
 249 /* Use the program counter to determine the contents and size of a
 250    breakpoint instruction.  Return a pointer to a string of bytes that
 251    encode a breakpoint instruction, store the length of the string in
 252    *LEN and optionally adjust *PC to point to the correct memory
 253    location for inserting the breakpoint.  */
 254
 255 static gdb_byte break_insn[] = { 3 };
 256
 257 GDBARCH_BREAKPOINT_MANIPULATION (vax, break_insn)
 258 \f
 259 /* Advance PC across any function entry prologue instructions
 260    to reach some "real" code.  */
 261
 262 static CORE_ADDR
 263 vax_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
 264 {
 265   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 266   gdb_byte op = read_memory_unsigned_integer (pc, 1, byte_order);
 267
 268   if (op == 0x11)
 269     pc += 2;                    /* skip brb */
 270   if (op == 0x31)
 271     pc += 3;                    /* skip brw */
 272   if (op == 0xC2
 273       && read_memory_unsigned_integer (pc + 2, 1, byte_order) == 0x5E)
 274     pc += 3;                    /* skip subl2 */
 275   if (op == 0x9E
 276       && read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xAE
 277       && read_memory_unsigned_integer (pc + 3, 1, byte_order) == 0x5E)
 278     pc += 4;                    /* skip movab */
 279   if (op == 0x9E
 280       && read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xCE
 281       && read_memory_unsigned_integer (pc + 4, 1, byte_order) == 0x5E)
 282     pc += 5;                    /* skip movab */
 283   if (op == 0x9E
 284       && read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xEE
 285       && read_memory_unsigned_integer (pc + 6, 1, byte_order) == 0x5E)
 286     pc += 7;                    /* skip movab */
 287
 288   return pc;
 289 }
 290 \f
 291
 292 /* Unwinding the stack is relatively easy since the VAX has a
 293    dedicated frame pointer, and frames are set up automatically as the
 294    result of a function call.  Most of the relevant information can be
 295    inferred from the documentation of the Procedure Call Instructions
 296    in the VAX MACRO and Instruction Set Reference Manual.  */
 297
 298 struct vax_frame_cache
 299 {
 300   /* Base address.  */
 301   CORE_ADDR base;
 302
 303   /* Table of saved registers.  */
 304   struct trad_frame_saved_reg *saved_regs;
 305 };
 306
 307 static struct vax_frame_cache *
 308 vax_frame_cache (struct frame_info *this_frame, void **this_cache)
 309 {
 310   struct vax_frame_cache *cache;
 311   CORE_ADDR addr;
 312   ULONGEST mask;
 313   int regnum;
 314
 315   if (*this_cache)
 316     return (struct vax_frame_cache *) *this_cache;
 317
 318   /* Allocate a new cache.  */
 319   cache = FRAME_OBSTACK_ZALLOC (struct vax_frame_cache);
 320   cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);
 321
 322   /* The frame pointer is used as the base for the frame.  */
 323   cache->base = get_frame_register_unsigned (this_frame, VAX_FP_REGNUM);
 324   if (cache->base == 0)
 325     return cache;
 326
 327   /* The register save mask and control bits determine the layout of
 328      the stack frame.  */
 329   mask = get_frame_memory_unsigned (this_frame, cache->base + 4, 4) >> 16;
 330
 331   /* These are always saved.  */
 332   cache->saved_regs[VAX_PC_REGNUM].addr = cache->base + 16;
 333   cache->saved_regs[VAX_FP_REGNUM].addr = cache->base + 12;
 334   cache->saved_regs[VAX_AP_REGNUM].addr = cache->base + 8;
 335   cache->saved_regs[VAX_PS_REGNUM].addr = cache->base + 4;
 336
 337   /* Scan the register save mask and record the location of the saved
 338      registers.  */
 339   addr = cache->base + 20;
 340   for (regnum = 0; regnum < VAX_AP_REGNUM; regnum++)
 341     {
 342       if (mask & (1 << regnum))
 343         {
 344           cache->saved_regs[regnum].addr = addr;
 345           addr += 4;
 346         }
 347     }
 348
 349   /* The CALLS/CALLG flag determines whether this frame has a General
 350      Argument List or a Stack Argument List.  */
 351   if (mask & (1 << 13))
 352     {
 353       ULONGEST numarg;
 354
 355       /* This is a procedure with Stack Argument List.  Adjust the
 356          stack address for the arguments that were pushed onto the
 357          stack.  The return instruction will automatically pop the
 358          arguments from the stack.  */
 359       numarg = get_frame_memory_unsigned (this_frame, addr, 1);
 360       addr += 4 + numarg * 4;
 361     }
 362
 363   /* Bits 1:0 of the stack pointer were saved in the control bits.  */
 364   trad_frame_set_value (cache->saved_regs, VAX_SP_REGNUM, addr + (mask >> 14));
 365
 366   return cache;
 367 }
 368
 369 static void
 370 vax_frame_this_id (struct frame_info *this_frame, void **this_cache,
 371                    struct frame_id *this_id)
 372 {
 373   struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);
 374
 375   /* This marks the outermost frame.  */
 376   if (cache->base == 0)
 377     return;
 378
 379   (*this_id) = frame_id_build (cache->base, get_frame_func (this_frame));
 380 }
 381
 382 static struct value *
 383 vax_frame_prev_register (struct frame_info *this_frame,
 384                          void **this_cache, int regnum)
 385 {
 386   struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);
 387
 388   return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum);
 389 }
 390
 391 static const struct frame_unwind vax_frame_unwind =
 392 {
 393   NORMAL_FRAME,
 394   default_frame_unwind_stop_reason,
 395   vax_frame_this_id,
 396   vax_frame_prev_register,
 397   NULL,
 398   default_frame_sniffer
 399 };
 400 \f
 401
 402 static CORE_ADDR
 403 vax_frame_base_address (struct frame_info *this_frame, void **this_cache)
 404 {
 405   struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);
 406
 407   return cache->base;
 408 }
 409
 410 static CORE_ADDR
 411 vax_frame_args_address (struct frame_info *this_frame, void **this_cache)
 412 {
 413   return get_frame_register_unsigned (this_frame, VAX_AP_REGNUM);
 414 }
 415
 416 static const struct frame_base vax_frame_base =
 417 {
 418   &vax_frame_unwind,
 419   vax_frame_base_address,
 420   vax_frame_base_address,
 421   vax_frame_args_address
 422 };
 423
 424 /* Return number of arguments for FRAME.  */
 425
 426 static int
 427 vax_frame_num_args (struct frame_info *frame)
 428 {
 429   CORE_ADDR args;
 430
 431   /* Assume that the argument pointer for the outermost frame is
 432      hosed, as is the case on NetBSD/vax ELF.  */
 433   if (get_frame_base_address (frame) == 0)
 434     return 0;
 435
 436   args = get_frame_register_unsigned (frame, VAX_AP_REGNUM);
 437   return get_frame_memory_unsigned (frame, args, 1);
 438 }
 439
 440 static CORE_ADDR
 441 vax_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
 442 {
 443   return frame_unwind_register_unsigned (next_frame, VAX_PC_REGNUM);
 444 }
 445 \f
 446
 447 /* Initialize the current architecture based on INFO.  If possible, re-use an
 448    architecture from ARCHES, which is a list of architectures already created
 449    during this debugging session.
 450
 451    Called e.g. at program startup, when reading a core file, and when reading
 452    a binary file.  */
 453
 454 static struct gdbarch *
 455 vax_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 456 {
 457   struct gdbarch *gdbarch;
 458
 459   /* If there is already a candidate, use it.  */
 460   arches = gdbarch_list_lookup_by_info (arches, &info);
 461   if (arches != NULL)
 462     return arches->gdbarch;
 463
 464   gdbarch = gdbarch_alloc (&info, NULL);
 465
 466   set_gdbarch_float_format (gdbarch, floatformats_vax_f);
 467   set_gdbarch_double_format (gdbarch, floatformats_vax_d);
 468   set_gdbarch_long_double_format (gdbarch, floatformats_vax_d);
 469   set_gdbarch_long_double_bit (gdbarch, 64);
 470
 471   /* Register info */
 472   set_gdbarch_num_regs (gdbarch, VAX_NUM_REGS);
 473   set_gdbarch_register_name (gdbarch, vax_register_name);
 474   set_gdbarch_register_type (gdbarch, vax_register_type);
 475   set_gdbarch_sp_regnum (gdbarch, VAX_SP_REGNUM);
 476   set_gdbarch_pc_regnum (gdbarch, VAX_PC_REGNUM);
 477   set_gdbarch_ps_regnum (gdbarch, VAX_PS_REGNUM);
 478
 479   set_gdbarch_iterate_over_regset_sections
 480     (gdbarch, vax_iterate_over_regset_sections);
 481
 482   /* Frame and stack info */
 483   set_gdbarch_skip_prologue (gdbarch, vax_skip_prologue);
 484   set_gdbarch_frame_num_args (gdbarch, vax_frame_num_args);
 485   set_gdbarch_frame_args_skip (gdbarch, 4);
 486
 487   /* Stack grows downward.  */
 488   set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
 489
 490   /* Return value info */
 491   set_gdbarch_return_value (gdbarch, vax_return_value);
 492
 493   /* Call dummy code.  */
 494   set_gdbarch_push_dummy_call (gdbarch, vax_push_dummy_call);
 495   set_gdbarch_dummy_id (gdbarch, vax_dummy_id);
 496
 497   /* Breakpoint info */
 498   SET_GDBARCH_BREAKPOINT_MANIPULATION (vax);
 499
 500   /* Misc info */
 501   set_gdbarch_deprecated_function_start_offset (gdbarch, 2);
 502   set_gdbarch_believe_pcc_promotion (gdbarch, 1);
 503
 504   set_gdbarch_print_insn (gdbarch, print_insn_vax);
 505
 506   set_gdbarch_unwind_pc (gdbarch, vax_unwind_pc);
 507
 508   frame_base_set_default (gdbarch, &vax_frame_base);
 509
 510   /* Hook in ABI-specific overrides, if they have been registered.  */
 511   gdbarch_init_osabi (info, gdbarch);
 512
 513   frame_unwind_append_unwinder (gdbarch, &vax_frame_unwind);
 514
 515   return (gdbarch);
 516 }
 517
 518 /* Provide a prototype to silence -Wmissing-prototypes.  */
 519 void _initialize_vax_tdep (void);
 520
 521 void
 522 _initialize_vax_tdep (void)
 523 {
 524   gdbarch_register (bfd_arch_vax, vax_gdbarch_init, NULL);
 525 }