gdb/rs6000-lynx178-tdep.c

   1 /* Copyright (C) 2012-2017 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 "value.h"
  26 #include "xcoffread.h"
  27
  28 /* Implement the "push_dummy_call" gdbarch method.  */
  29
  30 static CORE_ADDR
  31 rs6000_lynx178_push_dummy_call (struct gdbarch *gdbarch,
  32                                 struct value *function,
  33                                 struct regcache *regcache, CORE_ADDR bp_addr,
  34                                 int nargs, struct value **args, CORE_ADDR sp,
  35                                 int struct_return, CORE_ADDR struct_addr)
  36 {
  37   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  38   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  39   int ii;
  40   int len = 0;
  41   int argno;                    /* current argument number */
  42   int argbytes;                 /* current argument byte */
  43   gdb_byte tmp_buffer[50];
  44   int f_argno = 0;              /* current floating point argno */
  45   int wordsize = gdbarch_tdep (gdbarch)->wordsize;
  46   CORE_ADDR func_addr = find_function_addr (function, NULL);
  47
  48   struct value *arg = 0;
  49   struct type *type;
  50
  51   ULONGEST saved_sp;
  52
  53   /* The calling convention this function implements assumes the
  54      processor has floating-point registers.  We shouldn't be using it
  55      on PPC variants that lack them.  */
  56   gdb_assert (ppc_floating_point_unit_p (gdbarch));
  57
  58   /* The first eight words of ther arguments are passed in registers.
  59      Copy them appropriately.  */
  60   ii = 0;
  61
  62   /* If the function is returning a `struct', then the first word
  63      (which will be passed in r3) is used for struct return address.
  64      In that case we should advance one word and start from r4
  65      register to copy parameters.  */
  66   if (struct_return)
  67     {
  68       regcache_raw_write_unsigned (regcache, tdep->ppc_gp0_regnum + 3,
  69                                    struct_addr);
  70       ii++;
  71     }
  72
  73   /* Effectively indirect call... gcc does...
  74
  75      return_val example( float, int);
  76
  77      eabi:
  78      float in fp0, int in r3
  79      offset of stack on overflow 8/16
  80      for varargs, must go by type.
  81      power open:
  82      float in r3&r4, int in r5
  83      offset of stack on overflow different
  84      both:
  85      return in r3 or f0.  If no float, must study how gcc emulates floats;
  86      pay attention to arg promotion.
  87      User may have to cast\args to handle promotion correctly
  88      since gdb won't know if prototype supplied or not.  */
  89
  90   for (argno = 0, argbytes = 0; argno < nargs && ii < 8; ++ii)
  91     {
  92       int reg_size = register_size (gdbarch, ii + 3);
  93
  94       arg = args[argno];
  95       type = check_typedef (value_type (arg));
  96       len = TYPE_LENGTH (type);
  97
  98       if (TYPE_CODE (type) == TYPE_CODE_FLT)
  99         {
 100
 101           /* Floating point arguments are passed in fpr's, as well as gpr's.
 102              There are 13 fpr's reserved for passing parameters.  At this point
 103              there is no way we would run out of them.
 104
 105              Always store the floating point value using the register's
 106              floating-point format.  */
 107           const int fp_regnum = tdep->ppc_fp0_regnum + 1 + f_argno;
 108           gdb_byte reg_val[PPC_MAX_REGISTER_SIZE];
 109           struct type *reg_type = register_type (gdbarch, fp_regnum);
 110
 111           gdb_assert (len <= 8);
 112
 113           convert_typed_floating (value_contents (arg), type,
 114                                   reg_val, reg_type);
 115           regcache_cooked_write (regcache, fp_regnum, reg_val);
 116           ++f_argno;
 117         }
 118
 119       if (len > reg_size)
 120         {
 121
 122           /* Argument takes more than one register.  */
 123           while (argbytes < len)
 124             {
 125               gdb_byte word[PPC_MAX_REGISTER_SIZE];
 126               memset (word, 0, reg_size);
 127               memcpy (word,
 128                       ((char *) value_contents (arg)) + argbytes,
 129                       (len - argbytes) > reg_size
 130                         ? reg_size : len - argbytes);
 131               regcache_cooked_write (regcache,
 132                                     tdep->ppc_gp0_regnum + 3 + ii,
 133                                     word);
 134               ++ii, argbytes += reg_size;
 135
 136               if (ii >= 8)
 137                 goto ran_out_of_registers_for_arguments;
 138             }
 139           argbytes = 0;
 140           --ii;
 141         }
 142       else
 143         {
 144           /* Argument can fit in one register.  No problem.  */
 145           gdb_byte word[PPC_MAX_REGISTER_SIZE];
 146
 147           memset (word, 0, reg_size);
 148           memcpy (word, value_contents (arg), len);
 149           regcache_cooked_write (regcache, tdep->ppc_gp0_regnum + 3 +ii, word);
 150         }
 151       ++argno;
 152     }
 153
 154 ran_out_of_registers_for_arguments:
 155
 156   regcache_cooked_read_unsigned (regcache,
 157                                  gdbarch_sp_regnum (gdbarch),
 158                                  &saved_sp);
 159
 160   /* Location for 8 parameters are always reserved.  */
 161   sp -= wordsize * 8;
 162
 163   /* Another six words for back chain, TOC register, link register, etc.  */
 164   sp -= wordsize * 6;
 165
 166   /* Stack pointer must be quadword aligned.  */
 167   sp = align_down (sp, 16);
 168
 169   /* If there are more arguments, allocate space for them in
 170      the stack, then push them starting from the ninth one.  */
 171
 172   if ((argno < nargs) || argbytes)
 173     {
 174       int space = 0, jj;
 175
 176       if (argbytes)
 177         {
 178           space += align_up (len - argbytes, 4);
 179           jj = argno + 1;
 180         }
 181       else
 182         jj = argno;
 183
 184       for (; jj < nargs; ++jj)
 185         {
 186           struct value *val = args[jj];
 187
 188           space += align_up (TYPE_LENGTH (value_type (val)), 4);
 189         }
 190
 191       /* Add location required for the rest of the parameters.  */
 192       space = align_up (space, 16);
 193       sp -= space;
 194
 195       /* This is another instance we need to be concerned about
 196          securing our stack space.  If we write anything underneath %sp
 197          (r1), we might conflict with the kernel who thinks he is free
 198          to use this area.  So, update %sp first before doing anything
 199          else.  */
 200
 201       regcache_raw_write_signed (regcache,
 202                                  gdbarch_sp_regnum (gdbarch), sp);
 203
 204       /* If the last argument copied into the registers didn't fit there
 205          completely, push the rest of it into stack.  */
 206
 207       if (argbytes)
 208         {
 209           write_memory (sp + 24 + (ii * 4),
 210                         value_contents (arg) + argbytes,
 211                         len - argbytes);
 212           ++argno;
 213           ii += align_up (len - argbytes, 4) / 4;
 214         }
 215
 216       /* Push the rest of the arguments into stack.  */
 217       for (; argno < nargs; ++argno)
 218         {
 219
 220           arg = args[argno];
 221           type = check_typedef (value_type (arg));
 222           len = TYPE_LENGTH (type);
 223
 224
 225           /* Float types should be passed in fpr's, as well as in the
 226              stack.  */
 227           if (TYPE_CODE (type) == TYPE_CODE_FLT && f_argno < 13)
 228             {
 229
 230               gdb_assert (len <= 8);
 231
 232               regcache_cooked_write (regcache,
 233                                      tdep->ppc_fp0_regnum + 1 + f_argno,
 234                                      value_contents (arg));
 235               ++f_argno;
 236             }
 237
 238           write_memory (sp + 24 + (ii * 4), value_contents (arg), len);
 239           ii += align_up (len, 4) / 4;
 240         }
 241     }
 242
 243   /* Set the stack pointer.  According to the ABI, the SP is meant to
 244      be set _before_ the corresponding stack space is used.  On AIX,
 245      this even applies when the target has been completely stopped!
 246      Not doing this can lead to conflicts with the kernel which thinks
 247      that it still has control over this not-yet-allocated stack
 248      region.  */
 249   regcache_raw_write_signed (regcache, gdbarch_sp_regnum (gdbarch), sp);
 250
 251   /* Set back chain properly.  */
 252   store_unsigned_integer (tmp_buffer, wordsize, byte_order, saved_sp);
 253   write_memory (sp, tmp_buffer, wordsize);
 254
 255   /* Point the inferior function call's return address at the dummy's
 256      breakpoint.  */
 257   regcache_raw_write_signed (regcache, tdep->ppc_lr_regnum, bp_addr);
 258
 259   target_store_registers (regcache, -1);
 260   return sp;
 261 }
 262
 263 /* Implement the "return_value" gdbarch method.  */
 264
 265 static enum return_value_convention
 266 rs6000_lynx178_return_value (struct gdbarch *gdbarch, struct value *function,
 267                              struct type *valtype, struct regcache *regcache,
 268                              gdb_byte *readbuf, const gdb_byte *writebuf)
 269 {
 270   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 271   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 272
 273   /* The calling convention this function implements assumes the
 274      processor has floating-point registers.  We shouldn't be using it
 275      on PowerPC variants that lack them.  */
 276   gdb_assert (ppc_floating_point_unit_p (gdbarch));
 277
 278   /* AltiVec extension: Functions that declare a vector data type as a
 279      return value place that return value in VR2.  */
 280   if (TYPE_CODE (valtype) == TYPE_CODE_ARRAY && TYPE_VECTOR (valtype)
 281       && TYPE_LENGTH (valtype) == 16)
 282     {
 283       if (readbuf)
 284         regcache_cooked_read (regcache, tdep->ppc_vr0_regnum + 2, readbuf);
 285       if (writebuf)
 286         regcache_cooked_write (regcache, tdep->ppc_vr0_regnum + 2, writebuf);
 287
 288       return RETURN_VALUE_REGISTER_CONVENTION;
 289     }
 290
 291   /* If the called subprogram returns an aggregate, there exists an
 292      implicit first argument, whose value is the address of a caller-
 293      allocated buffer into which the callee is assumed to store its
 294      return value.  All explicit parameters are appropriately
 295      relabeled.  */
 296   if (TYPE_CODE (valtype) == TYPE_CODE_STRUCT
 297       || TYPE_CODE (valtype) == TYPE_CODE_UNION
 298       || TYPE_CODE (valtype) == TYPE_CODE_ARRAY)
 299     return RETURN_VALUE_STRUCT_CONVENTION;
 300
 301   /* Scalar floating-point values are returned in FPR1 for float or
 302      double, and in FPR1:FPR2 for quadword precision.  Fortran
 303      complex*8 and complex*16 are returned in FPR1:FPR2, and
 304      complex*32 is returned in FPR1:FPR4.  */
 305   if (TYPE_CODE (valtype) == TYPE_CODE_FLT
 306       && (TYPE_LENGTH (valtype) == 4 || TYPE_LENGTH (valtype) == 8))
 307     {
 308       struct type *regtype = register_type (gdbarch, tdep->ppc_fp0_regnum);
 309       gdb_byte regval[8];
 310
 311       /* FIXME: kettenis/2007-01-01: Add support for quadword
 312          precision and complex.  */
 313
 314       if (readbuf)
 315         {
 316           regcache_cooked_read (regcache, tdep->ppc_fp0_regnum + 1, regval);
 317           convert_typed_floating (regval, regtype, readbuf, valtype);
 318         }
 319       if (writebuf)
 320         {
 321           convert_typed_floating (writebuf, valtype, regval, regtype);
 322           regcache_cooked_write (regcache, tdep->ppc_fp0_regnum + 1, regval);
 323         }
 324
 325       return RETURN_VALUE_REGISTER_CONVENTION;
 326   }
 327
 328   /* Values of the types int, long, short, pointer, and char (length
 329      is less than or equal to four bytes), as well as bit values of
 330      lengths less than or equal to 32 bits, must be returned right
 331      justified in GPR3 with signed values sign extended and unsigned
 332      values zero extended, as necessary.  */
 333   if (TYPE_LENGTH (valtype) <= tdep->wordsize)
 334     {
 335       if (readbuf)
 336         {
 337           ULONGEST regval;
 338
 339           /* For reading we don't have to worry about sign extension.  */
 340           regcache_cooked_read_unsigned (regcache, tdep->ppc_gp0_regnum + 3,
 341                                          &regval);
 342           store_unsigned_integer (readbuf, TYPE_LENGTH (valtype), byte_order,
 343                                   regval);
 344         }
 345       if (writebuf)
 346         {
 347           /* For writing, use unpack_long since that should handle any
 348              required sign extension.  */
 349           regcache_cooked_write_unsigned (regcache, tdep->ppc_gp0_regnum + 3,
 350                                           unpack_long (valtype, writebuf));
 351         }
 352
 353       return RETURN_VALUE_REGISTER_CONVENTION;
 354     }
 355
 356   /* Eight-byte non-floating-point scalar values must be returned in
 357      GPR3:GPR4.  */
 358
 359   if (TYPE_LENGTH (valtype) == 8)
 360     {
 361       gdb_assert (TYPE_CODE (valtype) != TYPE_CODE_FLT);
 362       gdb_assert (tdep->wordsize == 4);
 363
 364       if (readbuf)
 365         {
 366           gdb_byte regval[8];
 367
 368           regcache_cooked_read (regcache, tdep->ppc_gp0_regnum + 3, regval);
 369           regcache_cooked_read (regcache, tdep->ppc_gp0_regnum + 4,
 370                                 regval + 4);
 371           memcpy (readbuf, regval, 8);
 372         }
 373       if (writebuf)
 374         {
 375           regcache_cooked_write (regcache, tdep->ppc_gp0_regnum + 3, writebuf);
 376           regcache_cooked_write (regcache, tdep->ppc_gp0_regnum + 4,
 377                                  writebuf + 4);
 378         }
 379
 380       return RETURN_VALUE_REGISTER_CONVENTION;
 381     }
 382
 383   return RETURN_VALUE_STRUCT_CONVENTION;
 384 }
 385
 386 /* PowerPC Lynx178 OSABI sniffer.  */
 387
 388 static enum gdb_osabi
 389 rs6000_lynx178_osabi_sniffer (bfd *abfd)
 390 {
 391   if (bfd_get_flavour (abfd) != bfd_target_xcoff_flavour)
 392     return GDB_OSABI_UNKNOWN;
 393
 394   /* The only noticeable difference between Lynx178 XCOFF files and
 395      AIX XCOFF files comes from the fact that there are no shared
 396      libraries on Lynx178.  So if the number of import files is
 397      different from zero, it cannot be a Lynx178 binary.  */
 398   if (xcoff_get_n_import_files (abfd) != 0)
 399     return GDB_OSABI_UNKNOWN;
 400
 401   return GDB_OSABI_LYNXOS178;
 402 }
 403
 404 /* Callback for powerpc-lynx178 initialization.  */
 405
 406 static void
 407 rs6000_lynx178_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch)
 408 {
 409   set_gdbarch_push_dummy_call (gdbarch, rs6000_lynx178_push_dummy_call);
 410   set_gdbarch_return_value (gdbarch, rs6000_lynx178_return_value);
 411   set_gdbarch_long_double_bit (gdbarch, 8 * TARGET_CHAR_BIT);
 412 }
 413
 414 void
 415 _initialize_rs6000_lynx178_tdep (void)
 416 {
 417   gdbarch_register_osabi_sniffer (bfd_arch_rs6000,
 418                                   bfd_target_xcoff_flavour,
 419                                   rs6000_lynx178_osabi_sniffer);
 420   gdbarch_register_osabi (bfd_arch_rs6000, 0, GDB_OSABI_LYNXOS178,
 421                           rs6000_lynx178_init_osabi);
 422 }
 423