gdb/rs6000-lynx178-tdep.c

   1 /* Copyright (C) 2012-2024 Free Software Foundation, Inc.
   2
   3    This file is part of GDB.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #include "defs.h"
  19 #include "osabi.h"
  20 #include "regcache.h"
  21 #include "gdbcore.h"
  22 #include "gdbtypes.h"
  23 #include "infcall.h"
  24 #include "ppc-tdep.h"
  25 #include "target-float.h"
  26 #include "value.h"
  27 #include "xcoffread.h"
  28
  29 /* Implement the "push_dummy_call" gdbarch method.  */
  30
  31 static CORE_ADDR
  32 rs6000_lynx178_push_dummy_call (struct gdbarch *gdbarch,
  33                                 struct value *function,
  34                                 struct regcache *regcache, CORE_ADDR bp_addr,
  35                                 int nargs, struct value **args, CORE_ADDR sp,
  36                                 function_call_return_method return_method,
  37                                 CORE_ADDR struct_addr)
  38 {
  39   ppc_gdbarch_tdep *tdep = gdbarch_tdep<ppc_gdbarch_tdep> (gdbarch);
  40   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  41   int ii;
  42   int len = 0;
  43   int argno;                    /* current argument number */
  44   int argbytes;                 /* current argument byte */
  45   gdb_byte tmp_buffer[50];
  46   int f_argno = 0;              /* current floating point argno */
  47   int wordsize = tdep->wordsize;
  48
  49   struct value *arg = 0;
  50   struct type *type;
  51
  52   ULONGEST saved_sp;
  53
  54   /* The calling convention this function implements assumes the
  55      processor has floating-point registers.  We shouldn't be using it
  56      on PPC variants that lack them.  */
  57   gdb_assert (ppc_floating_point_unit_p (gdbarch));
  58
  59   /* The first eight words of ther arguments are passed in registers.
  60      Copy them appropriately.  */
  61   ii = 0;
  62
  63   /* If the function is returning a `struct', then the first word
  64      (which will be passed in r3) is used for struct return address.
  65      In that case we should advance one word and start from r4
  66      register to copy parameters.  */
  67   if (return_method == return_method_struct)
  68     {
  69       regcache_raw_write_unsigned (regcache, tdep->ppc_gp0_regnum + 3,
  70                                    struct_addr);
  71       ii++;
  72     }
  73
  74   /* Effectively indirect call... gcc does...
  75
  76      return_val example( float, int);
  77
  78      eabi:
  79      float in fp0, int in r3
  80      offset of stack on overflow 8/16
  81      for varargs, must go by type.
  82      power open:
  83      float in r3&r4, int in r5
  84      offset of stack on overflow different
  85      both:
  86      return in r3 or f0.  If no float, must study how gcc emulates floats;
  87      pay attention to arg promotion.
  88      User may have to cast\args to handle promotion correctly
  89      since gdb won't know if prototype supplied or not.  */
  90
  91   for (argno = 0, argbytes = 0; argno < nargs && ii < 8; ++ii)
  92     {
  93       int reg_size = register_size (gdbarch, ii + 3);
  94
  95       arg = args[argno];
  96       type = check_typedef (arg->type ());
  97       len = type->length ();
  98
  99       if (type->code () == TYPE_CODE_FLT)
 100         {
 101
 102           /* Floating point arguments are passed in fpr's, as well as gpr's.
 103              There are 13 fpr's reserved for passing parameters.  At this point
 104              there is no way we would run out of them.
 105
 106              Always store the floating point value using the register's
 107              floating-point format.  */
 108           const int fp_regnum = tdep->ppc_fp0_regnum + 1 + f_argno;
 109           gdb_byte reg_val[PPC_MAX_REGISTER_SIZE];
 110           struct type *reg_type = register_type (gdbarch, fp_regnum);
 111
 112           gdb_assert (len <= 8);
 113
 114           target_float_convert (arg->contents ().data (), type, reg_val,
 115                                 reg_type);
 116           regcache->cooked_write (fp_regnum, reg_val);
 117           ++f_argno;
 118         }
 119
 120       if (len > reg_size)
 121         {
 122
 123           /* Argument takes more than one register.  */
 124           while (argbytes < len)
 125             {
 126               gdb_byte word[PPC_MAX_REGISTER_SIZE];
 127               memset (word, 0, reg_size);
 128               memcpy (word,
 129                       ((char *) arg->contents ().data ()) + argbytes,
 130                       (len - argbytes) > reg_size
 131                         ? reg_size : len - argbytes);
 132               regcache->cooked_write (tdep->ppc_gp0_regnum + 3 + ii, word);
 133               ++ii, argbytes += reg_size;
 134
 135               if (ii >= 8)
 136                 goto ran_out_of_registers_for_arguments;
 137             }
 138           argbytes = 0;
 139           --ii;
 140         }
 141       else
 142         {
 143           /* Argument can fit in one register.  No problem.  */
 144           gdb_byte word[PPC_MAX_REGISTER_SIZE];
 145
 146           memset (word, 0, reg_size);
 147           memcpy (word, arg->contents ().data (), len);
 148           regcache->cooked_write (tdep->ppc_gp0_regnum + 3 +ii, word);
 149         }
 150       ++argno;
 151     }
 152
 153 ran_out_of_registers_for_arguments:
 154
 155   regcache_cooked_read_unsigned (regcache,
 156                                  gdbarch_sp_regnum (gdbarch),
 157                                  &saved_sp);
 158
 159   /* Location for 8 parameters are always reserved.  */
 160   sp -= wordsize * 8;
 161
 162   /* Another six words for back chain, TOC register, link register, etc.  */
 163   sp -= wordsize * 6;
 164
 165   /* Stack pointer must be quadword aligned.  */
 166   sp = align_down (sp, 16);
 167
 168   /* If there are more arguments, allocate space for them in
 169      the stack, then push them starting from the ninth one.  */
 170
 171   if ((argno < nargs) || argbytes)
 172     {
 173       int space = 0, jj;
 174
 175       if (argbytes)
 176         {
 177           space += align_up (len - argbytes, 4);
 178           jj = argno + 1;
 179         }
 180       else
 181         jj = argno;
 182
 183       for (; jj < nargs; ++jj)
 184         {
 185           struct value *val = args[jj];
 186
 187           space += align_up (val->type ()->length (), 4);
 188         }
 189
 190       /* Add location required for the rest of the parameters.  */
 191       space = align_up (space, 16);
 192       sp -= space;
 193
 194       /* This is another instance we need to be concerned about
 195          securing our stack space.  If we write anything underneath %sp
 196          (r1), we might conflict with the kernel who thinks he is free
 197          to use this area.  So, update %sp first before doing anything
 198          else.  */
 199
 200       regcache_raw_write_signed (regcache,
 201                                  gdbarch_sp_regnum (gdbarch), sp);
 202
 203       /* If the last argument copied into the registers didn't fit there
 204          completely, push the rest of it into stack.  */
 205
 206       if (argbytes)
 207         {
 208           write_memory (sp + 24 + (ii * 4),
 209                         arg->contents ().data () + argbytes,
 210                         len - argbytes);
 211           ++argno;
 212           ii += align_up (len - argbytes, 4) / 4;
 213         }
 214
 215       /* Push the rest of the arguments into stack.  */
 216       for (; argno < nargs; ++argno)
 217         {
 218
 219           arg = args[argno];
 220           type = check_typedef (arg->type ());
 221           len = type->length ();
 222
 223
 224           /* Float types should be passed in fpr's, as well as in the
 225              stack.  */
 226           if (type->code () == TYPE_CODE_FLT && f_argno < 13)
 227             {
 228
 229               gdb_assert (len <= 8);
 230
 231               regcache->cooked_write (tdep->ppc_fp0_regnum + 1 + f_argno,
 232                                       arg->contents ().data ());
 233               ++f_argno;
 234             }
 235
 236           write_memory (sp + 24 + (ii * 4), arg->contents ().data (), len);
 237           ii += align_up (len, 4) / 4;
 238         }
 239     }
 240
 241   /* Set the stack pointer.  According to the ABI, the SP is meant to
 242      be set _before_ the corresponding stack space is used.  On AIX,
 243      this even applies when the target has been completely stopped!
 244      Not doing this can lead to conflicts with the kernel which thinks
 245      that it still has control over this not-yet-allocated stack
 246      region.  */
 247   regcache_raw_write_signed (regcache, gdbarch_sp_regnum (gdbarch), sp);
 248
 249   /* Set back chain properly.  */
 250   store_unsigned_integer (tmp_buffer, wordsize, byte_order, saved_sp);
 251   write_memory (sp, tmp_buffer, wordsize);
 252
 253   /* Point the inferior function call's return address at the dummy's
 254      breakpoint.  */
 255   regcache_raw_write_signed (regcache, tdep->ppc_lr_regnum, bp_addr);
 256
 257   target_store_registers (regcache, -1);
 258   return sp;
 259 }
 260
 261 /* Implement the "return_value" gdbarch method.  */
 262
 263 static enum return_value_convention
 264 rs6000_lynx178_return_value (struct gdbarch *gdbarch, struct value *function,
 265                              struct type *valtype, struct regcache *regcache,
 266                              gdb_byte *readbuf, const gdb_byte *writebuf)
 267 {
 268   ppc_gdbarch_tdep *tdep = gdbarch_tdep<ppc_gdbarch_tdep> (gdbarch);
 269   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 270
 271   /* The calling convention this function implements assumes the
 272      processor has floating-point registers.  We shouldn't be using it
 273      on PowerPC variants that lack them.  */
 274   gdb_assert (ppc_floating_point_unit_p (gdbarch));
 275
 276   /* AltiVec extension: Functions that declare a vector data type as a
 277      return value place that return value in VR2.  */
 278   if (valtype->code () == TYPE_CODE_ARRAY && valtype->is_vector ()
 279       && valtype->length () == 16)
 280     {
 281       if (readbuf)
 282         regcache->cooked_read (tdep->ppc_vr0_regnum + 2, readbuf);
 283       if (writebuf)
 284         regcache->cooked_write (tdep->ppc_vr0_regnum + 2, writebuf);
 285
 286       return RETURN_VALUE_REGISTER_CONVENTION;
 287     }
 288
 289   /* If the called subprogram returns an aggregate, there exists an
 290      implicit first argument, whose value is the address of a caller-
 291      allocated buffer into which the callee is assumed to store its
 292      return value.  All explicit parameters are appropriately
 293      relabeled.  */
 294   if (valtype->code () == TYPE_CODE_STRUCT
 295       || valtype->code () == TYPE_CODE_UNION
 296       || valtype->code () == TYPE_CODE_ARRAY)
 297     return RETURN_VALUE_STRUCT_CONVENTION;
 298
 299   /* Scalar floating-point values are returned in FPR1 for float or
 300      double, and in FPR1:FPR2 for quadword precision.  Fortran
 301      complex*8 and complex*16 are returned in FPR1:FPR2, and
 302      complex*32 is returned in FPR1:FPR4.  */
 303   if (valtype->code () == TYPE_CODE_FLT
 304       && (valtype->length () == 4 || valtype->length () == 8))
 305     {
 306       struct type *regtype = register_type (gdbarch, tdep->ppc_fp0_regnum);
 307       gdb_byte regval[8];
 308
 309       /* FIXME: kettenis/2007-01-01: Add support for quadword
 310          precision and complex.  */
 311
 312       if (readbuf)
 313         {
 314           regcache->cooked_read (tdep->ppc_fp0_regnum + 1, regval);
 315           target_float_convert (regval, regtype, readbuf, valtype);
 316         }
 317       if (writebuf)
 318         {
 319           target_float_convert (writebuf, valtype, regval, regtype);
 320           regcache->cooked_write (tdep->ppc_fp0_regnum + 1, regval);
 321         }
 322
 323       return RETURN_VALUE_REGISTER_CONVENTION;
 324   }
 325
 326   /* Values of the types int, long, short, pointer, and char (length
 327      is less than or equal to four bytes), as well as bit values of
 328      lengths less than or equal to 32 bits, must be returned right
 329      justified in GPR3 with signed values sign extended and unsigned
 330      values zero extended, as necessary.  */
 331   if (valtype->length () <= tdep->wordsize)
 332     {
 333       if (readbuf)
 334         {
 335           ULONGEST regval;
 336
 337           /* For reading we don't have to worry about sign extension.  */
 338           regcache_cooked_read_unsigned (regcache, tdep->ppc_gp0_regnum + 3,
 339                                          &regval);
 340           store_unsigned_integer (readbuf, valtype->length (), byte_order,
 341                                   regval);
 342         }
 343       if (writebuf)
 344         {
 345           /* For writing, use unpack_long since that should handle any
 346              required sign extension.  */
 347           regcache_cooked_write_unsigned (regcache, tdep->ppc_gp0_regnum + 3,
 348                                           unpack_long (valtype, writebuf));
 349         }
 350
 351       return RETURN_VALUE_REGISTER_CONVENTION;
 352     }
 353
 354   /* Eight-byte non-floating-point scalar values must be returned in
 355      GPR3:GPR4.  */
 356
 357   if (valtype->length () == 8)
 358     {
 359       gdb_assert (valtype->code () != TYPE_CODE_FLT);
 360       gdb_assert (tdep->wordsize == 4);
 361
 362       if (readbuf)
 363         {
 364           gdb_byte regval[8];
 365
 366           regcache->cooked_read (tdep->ppc_gp0_regnum + 3, regval);
 367           regcache->cooked_read (tdep->ppc_gp0_regnum + 4, regval + 4);
 368           memcpy (readbuf, regval, 8);
 369         }
 370       if (writebuf)
 371         {
 372           regcache->cooked_write (tdep->ppc_gp0_regnum + 3, writebuf);
 373           regcache->cooked_write (tdep->ppc_gp0_regnum + 4, writebuf + 4);
 374         }
 375
 376       return RETURN_VALUE_REGISTER_CONVENTION;
 377     }
 378
 379   return RETURN_VALUE_STRUCT_CONVENTION;
 380 }
 381
 382 /* PowerPC Lynx178 OSABI sniffer.  */
 383
 384 static enum gdb_osabi
 385 rs6000_lynx178_osabi_sniffer (bfd *abfd)
 386 {
 387   if (bfd_get_flavour (abfd) != bfd_target_xcoff_flavour)
 388     return GDB_OSABI_UNKNOWN;
 389
 390   /* The only noticeable difference between Lynx178 XCOFF files and
 391      AIX XCOFF files comes from the fact that there are no shared
 392      libraries on Lynx178.  So if the number of import files is
 393      different from zero, it cannot be a Lynx178 binary.  */
 394   if (xcoff_get_n_import_files (abfd) != 0)
 395     return GDB_OSABI_UNKNOWN;
 396
 397   return GDB_OSABI_LYNXOS178;
 398 }
 399
 400 /* Callback for powerpc-lynx178 initialization.  */
 401
 402 static void
 403 rs6000_lynx178_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch)
 404 {
 405   set_gdbarch_push_dummy_call (gdbarch, rs6000_lynx178_push_dummy_call);
 406   set_gdbarch_return_value (gdbarch, rs6000_lynx178_return_value);
 407   set_gdbarch_long_double_bit (gdbarch, 8 * TARGET_CHAR_BIT);
 408 }
 409
 410 void _initialize_rs6000_lynx178_tdep ();
 411 void
 412 _initialize_rs6000_lynx178_tdep ()
 413 {
 414   gdbarch_register_osabi_sniffer (bfd_arch_rs6000,
 415                                   bfd_target_xcoff_flavour,
 416                                   rs6000_lynx178_osabi_sniffer);
 417   gdbarch_register_osabi (bfd_arch_rs6000, 0, GDB_OSABI_LYNXOS178,
 418                           rs6000_lynx178_init_osabi);
 419 }
 420