gdb/vax-tdep.c

   1 /* Target-dependent code for the VAX.
   2
   3    Copyright (C) 1986-2023 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 "frame.h"
  24 #include "frame-base.h"
  25 #include "frame-unwind.h"
  26 #include "gdbcore.h"
  27 #include "gdbtypes.h"
  28 #include "osabi.h"
  29 #include "regcache.h"
  30 #include "regset.h"
  31 #include "trad-frame.h"
  32 #include "value.h"
  33
  34 #include "vax-tdep.h"
  35
  36 /* Return the name of register REGNUM.  */
  37
  38 static const char *
  39 vax_register_name (struct gdbarch *gdbarch, int regnum)
  40 {
  41   static const char *register_names[] =
  42   {
  43     "r0", "r1", "r2",  "r3",  "r4", "r5", "r6", "r7",
  44     "r8", "r9", "r10", "r11", "ap", "fp", "sp", "pc",
  45     "ps",
  46   };
  47
  48   gdb_static_assert (VAX_NUM_REGS == ARRAY_SIZE (register_names));
  49   return register_names[regnum];
  50 }
  51
  52 /* Return the GDB type object for the "standard" data type of data in
  53    register REGNUM.  */
  54
  55 static struct type *
  56 vax_register_type (struct gdbarch *gdbarch, int regnum)
  57 {
  58   return builtin_type (gdbarch)->builtin_int;
  59 }
  60 \f
  61 /* Core file support.  */
  62
  63 /* Supply register REGNUM from the buffer specified by GREGS and LEN
  64    in the general-purpose register set REGSET to register cache
  65    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  66
  67 static void
  68 vax_supply_gregset (const struct regset *regset, struct regcache *regcache,
  69                     int regnum, const void *gregs, size_t len)
  70 {
  71   const gdb_byte *regs = (const gdb_byte *) gregs;
  72   int i;
  73
  74   for (i = 0; i < VAX_NUM_REGS; i++)
  75     {
  76       if (regnum == i || regnum == -1)
  77         regcache->raw_supply (i, regs + i * 4);
  78     }
  79 }
  80
  81 /* VAX register set.  */
  82
  83 static const struct regset vax_gregset =
  84 {
  85   NULL,
  86   vax_supply_gregset
  87 };
  88
  89 /* Iterate over core file register note sections.  */
  90
  91 static void
  92 vax_iterate_over_regset_sections (struct gdbarch *gdbarch,
  93                                   iterate_over_regset_sections_cb *cb,
  94                                   void *cb_data,
  95                                   const struct regcache *regcache)
  96 {
  97   cb (".reg", VAX_NUM_REGS * 4, VAX_NUM_REGS * 4, &vax_gregset, NULL, cb_data);
  98 }
  99 \f
 100 /* The VAX UNIX calling convention uses R1 to pass a structure return
 101    value address instead of passing it as a first (hidden) argument as
 102    the VMS calling convention suggests.  */
 103
 104 static CORE_ADDR
 105 vax_store_arguments (struct regcache *regcache, int nargs,
 106                      struct value **args, CORE_ADDR sp)
 107 {
 108   struct gdbarch *gdbarch = regcache->arch ();
 109   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 110   gdb_byte buf[4];
 111   int count = 0;
 112   int i;
 113
 114   /* We create an argument list on the stack, and make the argument
 115      pointer to it.  */
 116
 117   /* Push arguments in reverse order.  */
 118   for (i = nargs - 1; i >= 0; i--)
 119     {
 120       int len = args[i]->enclosing_type ()->length ();
 121
 122       sp -= (len + 3) & ~3;
 123       count += (len + 3) / 4;
 124       write_memory (sp, args[i]->contents_all ().data (), len);
 125     }
 126
 127   /* Push argument count.  */
 128   sp -= 4;
 129   store_unsigned_integer (buf, 4, byte_order, count);
 130   write_memory (sp, buf, 4);
 131
 132   /* Update the argument pointer.  */
 133   store_unsigned_integer (buf, 4, byte_order, sp);
 134   regcache->cooked_write (VAX_AP_REGNUM, buf);
 135
 136   return sp;
 137 }
 138
 139 static CORE_ADDR
 140 vax_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
 141                      struct regcache *regcache, CORE_ADDR bp_addr, int nargs,
 142                      struct value **args, CORE_ADDR sp,
 143                      function_call_return_method return_method,
 144                      CORE_ADDR struct_addr)
 145 {
 146   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 147   CORE_ADDR fp = sp;
 148   gdb_byte buf[4];
 149
 150   /* Set up the function arguments.  */
 151   sp = vax_store_arguments (regcache, nargs, args, sp);
 152
 153   /* Store return value address.  */
 154   if (return_method == return_method_struct)
 155     regcache_cooked_write_unsigned (regcache, VAX_R1_REGNUM, struct_addr);
 156
 157   /* Store return address in the PC slot.  */
 158   sp -= 4;
 159   store_unsigned_integer (buf, 4, byte_order, bp_addr);
 160   write_memory (sp, buf, 4);
 161
 162   /* Store the (fake) frame pointer in the FP slot.  */
 163   sp -= 4;
 164   store_unsigned_integer (buf, 4, byte_order, fp);
 165   write_memory (sp, buf, 4);
 166
 167   /* Skip the AP slot.  */
 168   sp -= 4;
 169
 170   /* Store register save mask and control bits.  */
 171   sp -= 4;
 172   store_unsigned_integer (buf, 4, byte_order, 0);
 173   write_memory (sp, buf, 4);
 174
 175   /* Store condition handler.  */
 176   sp -= 4;
 177   store_unsigned_integer (buf, 4, byte_order, 0);
 178   write_memory (sp, buf, 4);
 179
 180   /* Update the stack pointer and frame pointer.  */
 181   store_unsigned_integer (buf, 4, byte_order, sp);
 182   regcache->cooked_write (VAX_SP_REGNUM, buf);
 183   regcache->cooked_write (VAX_FP_REGNUM, buf);
 184
 185   /* Return the saved (fake) frame pointer.  */
 186   return fp;
 187 }
 188
 189 static struct frame_id
 190 vax_dummy_id (struct gdbarch *gdbarch, frame_info_ptr this_frame)
 191 {
 192   CORE_ADDR fp;
 193
 194   fp = get_frame_register_unsigned (this_frame, VAX_FP_REGNUM);
 195   return frame_id_build (fp, get_frame_pc (this_frame));
 196 }
 197 \f
 198
 199 static enum return_value_convention
 200 vax_return_value (struct gdbarch *gdbarch, struct value *function,
 201                   struct type *type, struct regcache *regcache,
 202                   gdb_byte *readbuf, const gdb_byte *writebuf)
 203 {
 204   int len = type->length ();
 205   gdb_byte buf[8];
 206
 207   if (type->code () == TYPE_CODE_STRUCT
 208       || type->code () == TYPE_CODE_UNION
 209       || type->code () == TYPE_CODE_ARRAY)
 210     {
 211       /* The default on VAX is to return structures in static memory.
 212          Consequently a function must return the address where we can
 213          find the return value.  */
 214
 215       if (readbuf)
 216         {
 217           ULONGEST addr;
 218
 219           regcache_raw_read_unsigned (regcache, VAX_R0_REGNUM, &addr);
 220           read_memory (addr, readbuf, len);
 221         }
 222
 223       return RETURN_VALUE_ABI_RETURNS_ADDRESS;
 224     }
 225
 226   if (readbuf)
 227     {
 228       /* Read the contents of R0 and (if necessary) R1.  */
 229       regcache->cooked_read (VAX_R0_REGNUM, buf);
 230       if (len > 4)
 231         regcache->cooked_read (VAX_R1_REGNUM, buf + 4);
 232       memcpy (readbuf, buf, len);
 233     }
 234   if (writebuf)
 235     {
 236       /* Read the contents to R0 and (if necessary) R1.  */
 237       memcpy (buf, writebuf, len);
 238       regcache->cooked_write (VAX_R0_REGNUM, buf);
 239       if (len > 4)
 240         regcache->cooked_write (VAX_R1_REGNUM, buf + 4);
 241     }
 242
 243   return RETURN_VALUE_REGISTER_CONVENTION;
 244 }
 245 \f
 246
 247 /* Use the program counter to determine the contents and size of a
 248    breakpoint instruction.  Return a pointer to a string of bytes that
 249    encode a breakpoint instruction, store the length of the string in
 250    *LEN and optionally adjust *PC to point to the correct memory
 251    location for inserting the breakpoint.  */
 252
 253 constexpr gdb_byte vax_break_insn[] = { 3 };
 254
 255 typedef BP_MANIPULATION (vax_break_insn) vax_breakpoint;
 256 \f
 257 /* Advance PC across any function entry prologue instructions
 258    to reach some "real" code.  */
 259
 260 static CORE_ADDR
 261 vax_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
 262 {
 263   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 264   gdb_byte op = read_memory_unsigned_integer (pc, 1, byte_order);
 265
 266   if (op == 0x11)
 267     pc += 2;                    /* skip brb */
 268   if (op == 0x31)
 269     pc += 3;                    /* skip brw */
 270   if (op == 0xC2
 271       && read_memory_unsigned_integer (pc + 2, 1, byte_order) == 0x5E)
 272     pc += 3;                    /* skip subl2 */
 273   if (op == 0x9E
 274       && read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xAE
 275       && read_memory_unsigned_integer (pc + 3, 1, byte_order) == 0x5E)
 276     pc += 4;                    /* skip movab */
 277   if (op == 0x9E
 278       && read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xCE
 279       && read_memory_unsigned_integer (pc + 4, 1, byte_order) == 0x5E)
 280     pc += 5;                    /* skip movab */
 281   if (op == 0x9E
 282       && read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xEE
 283       && read_memory_unsigned_integer (pc + 6, 1, byte_order) == 0x5E)
 284     pc += 7;                    /* skip movab */
 285
 286   return pc;
 287 }
 288 \f
 289
 290 /* Unwinding the stack is relatively easy since the VAX has a
 291    dedicated frame pointer, and frames are set up automatically as the
 292    result of a function call.  Most of the relevant information can be
 293    inferred from the documentation of the Procedure Call Instructions
 294    in the VAX MACRO and Instruction Set Reference Manual.  */
 295
 296 struct vax_frame_cache
 297 {
 298   /* Base address.  */
 299   CORE_ADDR base;
 300
 301   /* Table of saved registers.  */
 302   trad_frame_saved_reg *saved_regs;
 303 };
 304
 305 static struct vax_frame_cache *
 306 vax_frame_cache (frame_info_ptr this_frame, void **this_cache)
 307 {
 308   struct vax_frame_cache *cache;
 309   CORE_ADDR addr;
 310   ULONGEST mask;
 311   int regnum;
 312
 313   if (*this_cache)
 314     return (struct vax_frame_cache *) *this_cache;
 315
 316   /* Allocate a new cache.  */
 317   cache = FRAME_OBSTACK_ZALLOC (struct vax_frame_cache);
 318   cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);
 319
 320   /* The frame pointer is used as the base for the frame.  */
 321   cache->base = get_frame_register_unsigned (this_frame, VAX_FP_REGNUM);
 322   if (cache->base == 0)
 323     return cache;
 324
 325   /* The register save mask and control bits determine the layout of
 326      the stack frame.  */
 327   mask = get_frame_memory_unsigned (this_frame, cache->base + 4, 4) >> 16;
 328
 329   /* These are always saved.  */
 330   cache->saved_regs[VAX_PC_REGNUM].set_addr (cache->base + 16);
 331   cache->saved_regs[VAX_FP_REGNUM].set_addr (cache->base + 12);
 332   cache->saved_regs[VAX_AP_REGNUM].set_addr (cache->base + 8);
 333   cache->saved_regs[VAX_PS_REGNUM].set_addr (cache->base + 4);
 334
 335   /* Scan the register save mask and record the location of the saved
 336      registers.  */
 337   addr = cache->base + 20;
 338   for (regnum = 0; regnum < VAX_AP_REGNUM; regnum++)
 339     {
 340       if (mask & (1 << regnum))
 341         {
 342           cache->saved_regs[regnum].set_addr (addr);
 343           addr += 4;
 344         }
 345     }
 346
 347   /* The CALLS/CALLG flag determines whether this frame has a General
 348      Argument List or a Stack Argument List.  */
 349   if (mask & (1 << 13))
 350     {
 351       ULONGEST numarg;
 352
 353       /* This is a procedure with Stack Argument List.  Adjust the
 354          stack address for the arguments that were pushed onto the
 355          stack.  The return instruction will automatically pop the
 356          arguments from the stack.  */
 357       numarg = get_frame_memory_unsigned (this_frame, addr, 1);
 358       addr += 4 + numarg * 4;
 359     }
 360
 361   /* Bits 1:0 of the stack pointer were saved in the control bits.  */
 362   cache->saved_regs[VAX_SP_REGNUM].set_value (addr + (mask >> 14));
 363
 364   return cache;
 365 }
 366
 367 static void
 368 vax_frame_this_id (frame_info_ptr this_frame, void **this_cache,
 369                    struct frame_id *this_id)
 370 {
 371   struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);
 372
 373   /* This marks the outermost frame.  */
 374   if (cache->base == 0)
 375     return;
 376
 377   (*this_id) = frame_id_build (cache->base, get_frame_func (this_frame));
 378 }
 379
 380 static struct value *
 381 vax_frame_prev_register (frame_info_ptr this_frame,
 382                          void **this_cache, int regnum)
 383 {
 384   struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);
 385
 386   return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum);
 387 }
 388
 389 static const struct frame_unwind vax_frame_unwind =
 390 {
 391   "vax prologue",
 392   NORMAL_FRAME,
 393   default_frame_unwind_stop_reason,
 394   vax_frame_this_id,
 395   vax_frame_prev_register,
 396   NULL,
 397   default_frame_sniffer
 398 };
 399 \f
 400
 401 static CORE_ADDR
 402 vax_frame_base_address (frame_info_ptr this_frame, void **this_cache)
 403 {
 404   struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);
 405
 406   return cache->base;
 407 }
 408
 409 static CORE_ADDR
 410 vax_frame_args_address (frame_info_ptr this_frame, void **this_cache)
 411 {
 412   return get_frame_register_unsigned (this_frame, VAX_AP_REGNUM);
 413 }
 414
 415 static const struct frame_base vax_frame_base =
 416 {
 417   &vax_frame_unwind,
 418   vax_frame_base_address,
 419   vax_frame_base_address,
 420   vax_frame_args_address
 421 };
 422
 423 /* Return number of arguments for FRAME.  */
 424
 425 static int
 426 vax_frame_num_args (frame_info_ptr frame)
 427 {
 428   CORE_ADDR args;
 429
 430   /* Assume that the argument pointer for the outermost frame is
 431      hosed, as is the case on NetBSD/vax ELF.  */
 432   if (get_frame_base_address (frame) == 0)
 433     return 0;
 434
 435   args = get_frame_register_unsigned (frame, VAX_AP_REGNUM);
 436   return get_frame_memory_unsigned (frame, args, 1);
 437 }
 438
 439 \f
 440
 441 /* Initialize the current architecture based on INFO.  If possible, re-use an
 442    architecture from ARCHES, which is a list of architectures already created
 443    during this debugging session.
 444
 445    Called e.g. at program startup, when reading a core file, and when reading
 446    a binary file.  */
 447
 448 static struct gdbarch *
 449 vax_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 450 {
 451   struct gdbarch *gdbarch;
 452
 453   /* If there is already a candidate, use it.  */
 454   arches = gdbarch_list_lookup_by_info (arches, &info);
 455   if (arches != NULL)
 456     return arches->gdbarch;
 457
 458   gdbarch = gdbarch_alloc (&info, NULL);
 459
 460   set_gdbarch_float_format (gdbarch, floatformats_vax_f);
 461   set_gdbarch_double_format (gdbarch, floatformats_vax_d);
 462   set_gdbarch_long_double_format (gdbarch, floatformats_vax_d);
 463   set_gdbarch_long_double_bit (gdbarch, 64);
 464
 465   /* Register info */
 466   set_gdbarch_num_regs (gdbarch, VAX_NUM_REGS);
 467   set_gdbarch_register_name (gdbarch, vax_register_name);
 468   set_gdbarch_register_type (gdbarch, vax_register_type);
 469   set_gdbarch_sp_regnum (gdbarch, VAX_SP_REGNUM);
 470   set_gdbarch_pc_regnum (gdbarch, VAX_PC_REGNUM);
 471   set_gdbarch_ps_regnum (gdbarch, VAX_PS_REGNUM);
 472
 473   set_gdbarch_iterate_over_regset_sections
 474     (gdbarch, vax_iterate_over_regset_sections);
 475
 476   /* Frame and stack info */
 477   set_gdbarch_skip_prologue (gdbarch, vax_skip_prologue);
 478   set_gdbarch_frame_num_args (gdbarch, vax_frame_num_args);
 479   set_gdbarch_frame_args_skip (gdbarch, 4);
 480
 481   /* Stack grows downward.  */
 482   set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
 483
 484   /* Return value info */
 485   set_gdbarch_return_value (gdbarch, vax_return_value);
 486
 487   /* Call dummy code.  */
 488   set_gdbarch_push_dummy_call (gdbarch, vax_push_dummy_call);
 489   set_gdbarch_dummy_id (gdbarch, vax_dummy_id);
 490
 491   /* Breakpoint info */
 492   set_gdbarch_breakpoint_kind_from_pc (gdbarch, vax_breakpoint::kind_from_pc);
 493   set_gdbarch_sw_breakpoint_from_kind (gdbarch, vax_breakpoint::bp_from_kind);
 494
 495   /* Misc info */
 496   set_gdbarch_deprecated_function_start_offset (gdbarch, 2);
 497   set_gdbarch_believe_pcc_promotion (gdbarch, 1);
 498
 499   frame_base_set_default (gdbarch, &vax_frame_base);
 500
 501   /* Hook in ABI-specific overrides, if they have been registered.  */
 502   gdbarch_init_osabi (info, gdbarch);
 503
 504   frame_unwind_append_unwinder (gdbarch, &vax_frame_unwind);
 505
 506   return (gdbarch);
 507 }
 508
 509 void _initialize_vax_tdep ();
 510 void
 511 _initialize_vax_tdep ()
 512 {
 513   gdbarch_register (bfd_arch_vax, vax_gdbarch_init, NULL);
 514 }