gdb/ppc64-tdep.c

   1 /* Common target-dependent code for ppc64 GDB, the GNU debugger.
   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 "frame.h"
  22 #include "gdbcore.h"
  23 #include "infrun.h"
  24 #include "ppc-tdep.h"
  25 #include "ppc64-tdep.h"
  26 #include "elf-bfd.h"
  27
  28 /* Macros for matching instructions.  Note that, since all the
  29    operands are masked off before they're or-ed into the instruction,
  30    you can use -1 to make masks.  */
  31
  32 #define insn_d(opcd, rts, ra, d)                \
  33   ((((unsigned (opcd)) & 0x3f) << 26)           \
  34    | (((unsigned (rts)) & 0x1f) << 21)          \
  35    | (((unsigned (ra)) & 0x1f) << 16)           \
  36    | ((unsigned (d)) & 0xffff))
  37
  38 #define insn_ds(opcd, rts, ra, d, xo)           \
  39   ((((unsigned (opcd)) & 0x3f) << 26)                      \
  40    | (((unsigned (rts)) & 0x1f) << 21)                     \
  41    | (((unsigned (ra)) & 0x1f) << 16)                      \
  42    | ((unsigned (d)) & 0xfffc)                             \
  43    | ((unsigned (xo)) & 0x3))
  44
  45 #define insn_xfx(opcd, rts, spr, xo)            \
  46   ((((unsigned (opcd)) & 0x3f) << 26)                      \
  47    | (((unsigned (rts)) & 0x1f) << 21)                     \
  48    | (((unsigned (spr)) & 0x1f) << 16)                     \
  49    | (((unsigned (spr)) & 0x3e0) << 6)                     \
  50    | (((unsigned (xo)) & 0x3ff) << 1))
  51
  52 #define prefix(a, b, R, do)                                \
  53   (((0x1) << 26)                                           \
  54    | (((unsigned (a)) & 0x3) << 24)                        \
  55    | (((unsigned (b)) & 0x1) << 23)                        \
  56    | (((unsigned (R)) & 0x1) << 20)                        \
  57    | ((unsigned (do)) & 0x3ffff))
  58
  59 #define insn_md(opcd, ra, rs, sh, me, rc)                  \
  60   ((((unsigned (opcd)) & 0x3f) << 26)                      \
  61    | (((unsigned (rs)) & 0x1f) << 21)                      \
  62    | (((unsigned (ra)) & 0x1f) << 16)                      \
  63    | (((unsigned (sh)) & 0x3e) << 11)                      \
  64    | (((unsigned (me)) & 0x3f) << 25)                      \
  65    | (((unsigned (sh)) & 0x1)  << 1)                       \
  66    | ((unsigned (rc)) & 0x1))
  67
  68 #define insn_x(opcd, rt, ra, rb, opc2)                     \
  69   ((((unsigned (opcd)) & 0x3f) << 26)                      \
  70    | (((unsigned (rt)) & 0x1f) << 21)                      \
  71    | (((unsigned (ra)) & 0x1f) << 16)                      \
  72    | (((unsigned (rb)) & 0x3e) << 11)                      \
  73    | (((unsigned (opc2)) & 0x3FF) << 1))
  74
  75 #define insn_xo(opcd, rt, ra, rb, oe, rc, opc2)            \
  76   ((((unsigned (opcd)) & 0x3f) << 26)                      \
  77    | (((unsigned (rt)) & 0x1f) << 21)                      \
  78    | (((unsigned (ra)) & 0x1f) << 16)                      \
  79    | (((unsigned (rb)) & 0x3e) << 11)                      \
  80    | (((unsigned (oe)) & 0x1) << 10)                       \
  81    | (((unsigned (opc2)) & 0x1FF) << 1)                    \
  82    | (((unsigned (rc)))))
  83
  84 /* PLT_OFF is the TOC-relative offset of a 64-bit PowerPC PLT entry.
  85    Return the function's entry point.  */
  86
  87 static CORE_ADDR
  88 ppc64_plt_entry_point (frame_info_ptr frame, CORE_ADDR plt_off)
  89 {
  90   struct gdbarch *gdbarch = get_frame_arch (frame);
  91   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  92   ppc_gdbarch_tdep *tdep = gdbarch_tdep<ppc_gdbarch_tdep> (gdbarch);
  93   CORE_ADDR tocp;
  94
  95   if (execution_direction == EXEC_REVERSE)
  96     {
  97       /* If executing in reverse, r2 will have been stored to the stack.  */
  98       CORE_ADDR sp = get_frame_register_unsigned (frame,
  99                                                   tdep->ppc_gp0_regnum + 1);
 100       unsigned int sp_off = tdep->elf_abi == POWERPC_ELF_V1 ? 40 : 24;
 101       tocp = read_memory_unsigned_integer (sp + sp_off, 8, byte_order);
 102     }
 103   else
 104     tocp = get_frame_register_unsigned (frame, tdep->ppc_gp0_regnum + 2);
 105
 106   /* The first word of the PLT entry is the function entry point.  */
 107   return read_memory_unsigned_integer (tocp + plt_off, 8, byte_order);
 108 }
 109
 110 static CORE_ADDR
 111 ppc64_plt_pcrel_entry_point (frame_info_ptr frame, CORE_ADDR plt_off,
 112                              CORE_ADDR pc)
 113 {
 114   struct gdbarch *gdbarch = get_frame_arch (frame);
 115   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 116
 117   /* Execution direction doesn't matter, entry is pc + plt_off either way.
 118      The first word of the PLT entry is the function entry point.  */
 119   return read_memory_unsigned_integer (pc + plt_off, 8, byte_order);
 120 }
 121
 122 /* Patterns for the standard linkage functions.  These are built by
 123    build_plt_stub in bfd/elf64-ppc.c.  */
 124
 125 /* Old ELFv1 PLT call stub.  */
 126
 127 static const struct ppc_insn_pattern ppc64_standard_linkage1[] =
 128   {
 129     /* addis r12, r2, <any> */
 130     { insn_d (-1, -1, -1, 0), insn_d (15, 12, 2, 0), 0 },
 131
 132     /* std r2, 40(r1) */
 133     { (unsigned) -1, insn_ds (62, 2, 1, 40, 0), 0 },
 134
 135     /* ld r11, <any>(r12) */
 136     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 12, 0, 0), 0 },
 137
 138     /* addis r12, r12, 1 <optional> */
 139     { insn_d (-1, -1, -1, -1), insn_d (15, 12, 12, 1), 1 },
 140
 141     /* ld r2, <any>(r12) */
 142     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 2, 12, 0, 0), 0 },
 143
 144     /* addis r12, r12, 1 <optional> */
 145     { insn_d (-1, -1, -1, -1), insn_d (15, 12, 12, 1), 1 },
 146
 147     /* mtctr r11 */
 148     { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 11, 9, 467), 0 },
 149
 150     /* ld r11, <any>(r12) <optional> */
 151     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 12, 0, 0), 1 },
 152
 153     /* bctr */
 154     { (unsigned) -1, 0x4e800420, 0 },
 155
 156     { 0, 0, 0 }
 157   };
 158
 159 /* ELFv1 PLT call stub to access PLT entries more than +/- 32k from r2.
 160    Also supports older stub with different placement of std 2,40(1),
 161    a stub that omits the std 2,40(1), and both versions of power7
 162    thread safety read barriers.  Note that there are actually two more
 163    instructions following "cmpldi r2, 0", "bnectr+" and "b <glink_i>",
 164    but there isn't any need to match them.  */
 165
 166 static const struct ppc_insn_pattern ppc64_standard_linkage2[] =
 167   {
 168     /* std r2, 40(r1) <optional> */
 169     { (unsigned) -1, insn_ds (62, 2, 1, 40, 0), 1 },
 170
 171     /* addis r12, r2, <any> */
 172     { insn_d (-1, -1, -1, 0), insn_d (15, 12, 2, 0), 0 },
 173
 174     /* std r2, 40(r1) <optional> */
 175     { (unsigned) -1, insn_ds (62, 2, 1, 40, 0), 1 },
 176
 177     /* ld r11, <any>(r12) */
 178     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 12, 0, 0), 0 },
 179
 180     /* addi r12, r12, <any> <optional> */
 181     { insn_d (-1, -1, -1, 0), insn_d (14, 12, 12, 0), 1 },
 182
 183     /* mtctr r11 */
 184     { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 11, 9, 467), 0 },
 185
 186     /* xor r11, r11, r11 <optional> */
 187     { (unsigned) -1, 0x7d6b5a78, 1 },
 188
 189     /* add r12, r12, r11 <optional> */
 190     { (unsigned) -1, 0x7d8c5a14, 1 },
 191
 192     /* ld r2, <any>(r12) */
 193     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 2, 12, 0, 0), 0 },
 194
 195     /* ld r11, <any>(r12) <optional> */
 196     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 12, 0, 0), 1 },
 197
 198     /* bctr <optional> */
 199     { (unsigned) -1, 0x4e800420, 1 },
 200
 201     /* cmpldi r2, 0 <optional> */
 202     { (unsigned) -1, 0x28220000, 1 },
 203
 204     { 0, 0, 0 }
 205   };
 206
 207 /* ELFv1 PLT call stub to access PLT entries within +/- 32k of r2.  */
 208
 209 static const struct ppc_insn_pattern ppc64_standard_linkage3[] =
 210   {
 211     /* std r2, 40(r1) <optional> */
 212     { (unsigned) -1, insn_ds (62, 2, 1, 40, 0), 1 },
 213
 214     /* ld r11, <any>(r2) */
 215     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 2, 0, 0), 0 },
 216
 217     /* addi r2, r2, <any> <optional> */
 218     { insn_d (-1, -1, -1, 0), insn_d (14, 2, 2, 0), 1 },
 219
 220     /* mtctr r11 */
 221     { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 11, 9, 467), 0 },
 222
 223     /* xor r11, r11, r11 <optional> */
 224     { (unsigned) -1, 0x7d6b5a78, 1 },
 225
 226     /* add r2, r2, r11 <optional> */
 227     { (unsigned) -1, 0x7c425a14, 1 },
 228
 229     /* ld r11, <any>(r2) <optional> */
 230     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 2, 0, 0), 1 },
 231
 232     /* ld r2, <any>(r2) */
 233     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 2, 2, 0, 0), 0 },
 234
 235     /* bctr <optional> */
 236     { (unsigned) -1, 0x4e800420, 1 },
 237
 238     /* cmpldi r2, 0 <optional> */
 239     { (unsigned) -1, 0x28220000, 1 },
 240
 241     { 0, 0, 0 }
 242   };
 243
 244 /* ELFv1 PLT call stub to access PLT entries more than +/- 32k from r2.
 245    A more modern variant of ppc64_standard_linkage2 differing in
 246    register usage.  */
 247
 248 static const struct ppc_insn_pattern ppc64_standard_linkage4[] =
 249   {
 250     /* std r2, 40(r1) <optional> */
 251     { (unsigned) -1, insn_ds (62, 2, 1, 40, 0), 1 },
 252
 253     /* addis r11, r2, <any> */
 254     { insn_d (-1, -1, -1, 0), insn_d (15, 11, 2, 0), 0 },
 255
 256     /* ld r12, <any>(r11) */
 257     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 12, 11, 0, 0), 0 },
 258
 259     /* addi r11, r11, <any> <optional> */
 260     { insn_d (-1, -1, -1, 0), insn_d (14, 11, 11, 0), 1 },
 261
 262     /* mtctr r12 */
 263     { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 },
 264
 265     /* xor r2, r12, r12 <optional> */
 266     { (unsigned) -1, 0x7d826278, 1 },
 267
 268     /* add r11, r11, r2 <optional> */
 269     { (unsigned) -1, 0x7d6b1214, 1 },
 270
 271     /* ld r2, <any>(r11) */
 272     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 2, 11, 0, 0), 0 },
 273
 274     /* ld r11, <any>(r11) <optional> */
 275     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 11, 0, 0), 1 },
 276
 277     /* bctr <optional> */
 278     { (unsigned) -1, 0x4e800420, 1 },
 279
 280     /* cmpldi r2, 0 <optional> */
 281     { (unsigned) -1, 0x28220000, 1 },
 282
 283     { 0, 0, 0 }
 284   };
 285
 286 /* ELFv1 PLT call stub to access PLT entries within +/- 32k of r2.
 287    A more modern variant of ppc64_standard_linkage3 differing in
 288    register usage.  */
 289
 290 static const struct ppc_insn_pattern ppc64_standard_linkage5[] =
 291   {
 292     /* std r2, 40(r1) <optional> */
 293     { (unsigned) -1, insn_ds (62, 2, 1, 40, 0), 1 },
 294
 295     /* ld r12, <any>(r2) */
 296     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 12, 2, 0, 0), 0 },
 297
 298     /* addi r2, r2, <any> <optional> */
 299     { insn_d (-1, -1, -1, 0), insn_d (14, 2, 2, 0), 1 },
 300
 301     /* mtctr r12 */
 302     { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 },
 303
 304     /* xor r11, r12, r12 <optional> */
 305     { (unsigned) -1, 0x7d8b6278, 1 },
 306
 307     /* add r2, r2, r11 <optional> */
 308     { (unsigned) -1, 0x7c425a14, 1 },
 309
 310     /* ld r11, <any>(r2) <optional> */
 311     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 2, 0, 0), 1 },
 312
 313     /* ld r2, <any>(r2) */
 314     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 2, 2, 0, 0), 0 },
 315
 316     /* bctr <optional> */
 317     { (unsigned) -1, 0x4e800420, 1 },
 318
 319     /* cmpldi r2, 0 <optional> */
 320     { (unsigned) -1, 0x28220000, 1 },
 321
 322     { 0, 0, 0 }
 323   };
 324
 325 /* ELFv2 PLT call stub to access PLT entries more than +/- 32k from r2.  */
 326
 327 static const struct ppc_insn_pattern ppc64_standard_linkage6[] =
 328   {
 329     /* std r2, 24(r1) <optional> */
 330     { (unsigned) -1, insn_ds (62, 2, 1, 24, 0), 1 },
 331
 332     /* addis r11, r2, <any> */
 333     { insn_d (-1, -1, -1, 0), insn_d (15, 11, 2, 0), 0 },
 334
 335     /* ld r12, <any>(r11) */
 336     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 12, 11, 0, 0), 0 },
 337
 338     /* mtctr r12 */
 339     { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 },
 340
 341     /* bctr */
 342     { (unsigned) -1, 0x4e800420, 0 },
 343
 344     { 0, 0, 0 }
 345   };
 346
 347 /* ELFv2 PLT call stub to access PLT entries within +/- 32k of r2.  */
 348
 349 static const struct ppc_insn_pattern ppc64_standard_linkage7[] =
 350   {
 351     /* std r2, 24(r1) <optional> */
 352     { (unsigned) -1, insn_ds (62, 2, 1, 24, 0), 1 },
 353
 354     /* ld r12, <any>(r2) */
 355     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 12, 2, 0, 0), 0 },
 356
 357     /* mtctr r12 */
 358     { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 },
 359
 360     /* bctr */
 361     { (unsigned) -1, 0x4e800420, 0 },
 362
 363     { 0, 0, 0 }
 364   };
 365
 366 /* ELFv2 PLT call stub to access PLT entries more than +/- 32k from r2,
 367    supporting fusion.  */
 368
 369 static const struct ppc_insn_pattern ppc64_standard_linkage8[] =
 370   {
 371     /* std r2, 24(r1) <optional> */
 372     { (unsigned) -1, insn_ds (62, 2, 1, 24, 0), 1 },
 373
 374     /* addis r12, r2, <any> */
 375     { insn_d (-1, -1, -1, 0), insn_d (15, 12, 2, 0), 0 },
 376
 377     /* ld r12, <any>(r12) */
 378     { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 12, 12, 0, 0), 0 },
 379
 380     /* mtctr r12 */
 381     { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 },
 382
 383     /* bctr */
 384     { (unsigned) -1, 0x4e800420, 0 },
 385
 386     { 0, 0, 0 }
 387   };
 388
 389 /* Power 10 ELFv2 PLT call stubs */
 390 static const struct ppc_insn_pattern ppc64_standard_linkage9[] =
 391   {
 392     /* std   %r2,0+40(%r1)   <optional> */
 393     { insn_ds (-1, -1, -1, 0, 1), insn_ds (62, 2, 1, 40, 0), 1 },
 394
 395     /* pld r12, <any> */
 396     { prefix (-1, -1, 1, 0), prefix (0, 0, 1, 0), 0 },
 397     { insn_d (-1, -1, -1, 0), insn_d (57, 12, 0, 0), 0 },
 398
 399     /* mtctr r12  */
 400     { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 },
 401
 402     /* bctr   */
 403     { (unsigned) -1, 0x4e800420, 0 },
 404
 405     { 0, 0, 0 }
 406   };
 407
 408 static const struct ppc_insn_pattern ppc64_standard_linkage10[] =
 409   {
 410     /* std   %r2,0+40(%r1)    <optional> */
 411     { insn_ds (-1, -1, -1, 0, 1), insn_ds (62, 2, 1, 40, 0), 1 },
 412
 413     /* paddi r12,<any> */
 414     { prefix (-1, -1, 1, 0), prefix (2, 0, 1, 0), 0 },
 415     { insn_d (-1, -1, -1, 0), insn_d (14, 12, 0, 0), 0 },
 416
 417     /* mtctr r12  <optional> */
 418     { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 },
 419
 420     /* bctr   */
 421     { (unsigned) -1, 0x4e800420, 0 },
 422
 423     { 0, 0, 0 }
 424   };
 425
 426 static const struct ppc_insn_pattern ppc64_standard_linkage11[] =
 427   {
 428     /* std   %r2,0+40(%r1)   <optional> */
 429     { insn_ds (-1, -1, -1, 0, 1), insn_ds (62, 2, 1, 40, 0), 1 },
 430
 431     /* li %r11,0     <optional> */
 432     { insn_d (-1, -1, -1, 0), insn_d (14, 11, 0, 0), 1 },
 433
 434     /* sldi  %r11,%r11,34   <eq to rldicr rx,ry,n, 63-n> <optional>  */
 435     { insn_md (-1, -1, -1, 0, 0, 1), insn_md (30, 11, 11, 34, 63-34, 0), 1 },
 436
 437     /* paddi r12, <any> */
 438     { prefix (-1, -1, 1, 0), prefix (2, 0, 1, 0), 0 },
 439     { insn_d (-1, -1, -1, 0), insn_d (14, 12, 0, 0), 0 },
 440
 441     /* ldx   %r12,%r11,%r12  <optional> */
 442     { (unsigned) -1, insn_x (31, 12, 11, 12, 21), 1 },
 443
 444     /* add   %r12,%r11,%r12  <optional> */
 445     { (unsigned) -1, insn_xo (31, 12, 11, 12, 0, 0, 40), 1 },
 446
 447     /* mtctr r12   */
 448     { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 },
 449
 450     /* bctr   */ // 13, 14, 15, 16
 451     { (unsigned) -1, 0x4e800420, 0 },
 452
 453     { 0, 0, 0 }
 454   };
 455
 456 static const struct ppc_insn_pattern ppc64_standard_linkage12[] =
 457   {
 458     /* std   %r2,0+40(%r1)    <optional>  */
 459     { insn_ds (-1, -1, -1, 0, 1), insn_ds (62, 2, 1, 40, 0), 1 },
 460
 461     /* lis %r11,xxx@ha <equivalent addis rx, 0, val> */
 462     /* addis r12, r2, <any> */
 463     { insn_d (-1, -1, -1, 0), insn_d (15, 12, 2, 0), 0 },
 464
 465     /* ori   %r11,%r11,xxx@l */
 466     { insn_d (-1, -1, -1, 0), insn_d (24, 11, 11, 0), 0 },
 467
 468     /* sldi  %r11,%r11,34 <optional> */
 469     { (unsigned) -1, insn_md (30, 11, 11, 34, 63-34, 0), 1 },
 470
 471     /*paddi r12,<any> */
 472     { prefix (-1, -1, 1, 0), prefix (2, 0, 1, 0), 0 },
 473     { insn_d (-1, -1, -1, 0), insn_d (14, 12, 0, 0), 0 },
 474
 475     /* sldi  %r11,%r11,34 <optional> */
 476     { (unsigned) -1, insn_md (30, 11, 11, 34, 63-34, 0), 1 },
 477
 478     /* ldx   %r12,%r11,%r12 <optional> */
 479     { (unsigned) -1, insn_x (31, 12, 11, 12, 21), 1 },
 480
 481     /* add   %r12,%r11,%r12 <optional> */
 482     { (unsigned) -1, insn_xo (31, 12, 11, 12, 0, 0, 40), 1 },
 483
 484     /* mtctr r12  */
 485     { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 },
 486
 487     /* bctr  */ // 17, 18, 19, 20
 488     { (unsigned) -1, 0x4e800420, 0 },
 489
 490     { 0, 0, 0 }
 491   };
 492
 493 /* When the dynamic linker is doing lazy symbol resolution, the first
 494    call to a function in another object will go like this:
 495
 496    - The user's function calls the linkage function:
 497
 498         100003d4:   4b ff ff ad     bl      10000380 <nnnn.plt_call.printf>
 499         100003d8:   e8 41 00 28     ld      r2,40(r1)
 500
 501    - The linkage function loads the entry point and toc pointer from
 502      the function descriptor in the PLT, and jumps to it:
 503
 504      <nnnn.plt_call.printf>:
 505         10000380:   f8 41 00 28     std     r2,40(r1)
 506         10000384:   e9 62 80 78     ld      r11,-32648(r2)
 507         10000388:   7d 69 03 a6     mtctr   r11
 508         1000038c:   e8 42 80 80     ld      r2,-32640(r2)
 509         10000390:   28 22 00 00     cmpldi  r2,0
 510         10000394:   4c e2 04 20     bnectr+
 511         10000398:   48 00 03 a0     b       10000738 <printf@plt>
 512
 513    - But since this is the first time that PLT entry has been used, it
 514      sends control to its glink entry.  That loads the number of the
 515      PLT entry and jumps to the common glink0 code:
 516
 517      <printf@plt>:
 518         10000738:   38 00 00 01     li      r0,1
 519         1000073c:   4b ff ff bc     b       100006f8 <__glink_PLTresolve>
 520
 521    - The common glink0 code then transfers control to the dynamic
 522      linker's fixup code:
 523
 524         100006f0:   0000000000010440 .quad plt0 - (. + 16)
 525      <__glink_PLTresolve>:
 526         100006f8:   7d 88 02 a6     mflr    r12
 527         100006fc:   42 9f 00 05     bcl     20,4*cr7+so,10000700
 528         10000700:   7d 68 02 a6     mflr    r11
 529         10000704:   e8 4b ff f0     ld      r2,-16(r11)
 530         10000708:   7d 88 03 a6     mtlr    r12
 531         1000070c:   7d 82 5a 14     add     r12,r2,r11
 532         10000710:   e9 6c 00 00     ld      r11,0(r12)
 533         10000714:   e8 4c 00 08     ld      r2,8(r12)
 534         10000718:   7d 69 03 a6     mtctr   r11
 535         1000071c:   e9 6c 00 10     ld      r11,16(r12)
 536         10000720:   4e 80 04 20     bctr
 537
 538    Eventually, this code will figure out how to skip all of this,
 539    including the dynamic linker.  At the moment, we just get through
 540    the linkage function.  */
 541
 542 /* If the current thread is about to execute a series of instructions
 543    matching the ppc64_standard_linkage pattern, and INSN is the result
 544    from that pattern match, return the code address to which the
 545    standard linkage function will send them.  (This doesn't deal with
 546    dynamic linker lazy symbol resolution stubs.)  */
 547
 548 static CORE_ADDR
 549 ppc64_standard_linkage1_target (frame_info_ptr frame, unsigned int *insn)
 550 {
 551   CORE_ADDR plt_off = ((ppc_insn_d_field (insn[0]) << 16)
 552                        + ppc_insn_ds_field (insn[2]));
 553
 554   return ppc64_plt_entry_point (frame, plt_off);
 555 }
 556
 557 static CORE_ADDR
 558 ppc64_standard_linkage2_target (frame_info_ptr frame, unsigned int *insn)
 559 {
 560   CORE_ADDR plt_off = ((ppc_insn_d_field (insn[1]) << 16)
 561                        + ppc_insn_ds_field (insn[3]));
 562
 563   return ppc64_plt_entry_point (frame, plt_off);
 564 }
 565
 566 static CORE_ADDR
 567 ppc64_standard_linkage3_target (frame_info_ptr frame, unsigned int *insn)
 568 {
 569   CORE_ADDR plt_off = ppc_insn_ds_field (insn[1]);
 570
 571   return ppc64_plt_entry_point (frame, plt_off);
 572 }
 573
 574 static CORE_ADDR
 575 ppc64_standard_linkage4_target (frame_info_ptr frame, unsigned int *insn)
 576 {
 577   CORE_ADDR plt_off = ((ppc_insn_d_field (insn[1]) << 16)
 578                        + ppc_insn_ds_field (insn[2]));
 579
 580   return ppc64_plt_entry_point (frame, plt_off);
 581 }
 582
 583 static CORE_ADDR
 584 ppc64_pcrel_linkage1_target (frame_info_ptr frame, unsigned int *insn,
 585                              CORE_ADDR pc)
 586 {
 587   /* insn[0] is for the std instruction.  */
 588   CORE_ADDR plt_off = ppc_insn_prefix_dform (insn[1], insn[2]);
 589
 590   return ppc64_plt_pcrel_entry_point (frame, plt_off, pc);
 591 }
 592
 593 static CORE_ADDR
 594 ppc64_pcrel_linkage2_target (frame_info_ptr frame, unsigned int *insn,
 595                              CORE_ADDR pc)
 596 {
 597   CORE_ADDR plt_off;
 598
 599   /* insn[0] is for the std instruction.
 600      insn[1] is for the  li r11 instruction  */
 601   plt_off = ppc_insn_prefix_dform (insn[2], insn[3]);
 602
 603   return ppc64_plt_pcrel_entry_point (frame, plt_off, pc);
 604 }
 605
 606
 607 /* Given that we've begun executing a call trampoline at PC, return
 608    the entry point of the function the trampoline will go to.
 609
 610    When the execution direction is EXEC_REVERSE, scan backward to
 611    check whether we are in the middle of a PLT stub.  */
 612
 613 static CORE_ADDR
 614 ppc64_skip_trampoline_code_1 (frame_info_ptr frame, CORE_ADDR pc)
 615 {
 616 #define MAX(a,b) ((a) > (b) ? (a) : (b))
 617   unsigned int insns[MAX (MAX (MAX (ARRAY_SIZE (ppc64_standard_linkage1),
 618                                     ARRAY_SIZE (ppc64_standard_linkage2)),
 619                                MAX (ARRAY_SIZE (ppc64_standard_linkage3),
 620                                     ARRAY_SIZE (ppc64_standard_linkage4))),
 621                       MAX(MAX (MAX (ARRAY_SIZE (ppc64_standard_linkage5),
 622                                     ARRAY_SIZE (ppc64_standard_linkage6)),
 623                                MAX (ARRAY_SIZE (ppc64_standard_linkage7),
 624                                     ARRAY_SIZE (ppc64_standard_linkage8))),
 625                           MAX (MAX (ARRAY_SIZE (ppc64_standard_linkage9),
 626                                     ARRAY_SIZE (ppc64_standard_linkage10)),
 627                                MAX (ARRAY_SIZE (ppc64_standard_linkage11),
 628                                     ARRAY_SIZE (ppc64_standard_linkage12)))))
 629
 630                      - 1];
 631   CORE_ADDR target;
 632   int scan_limit, i;
 633
 634   scan_limit = 1;
 635   /* When reverse-debugging, scan backward to check whether we are
 636      in the middle of trampoline code.  */
 637   if (execution_direction == EXEC_REVERSE)
 638     scan_limit = ARRAY_SIZE (insns) - 1;
 639
 640   for (i = 0; i < scan_limit; i++)
 641     {
 642       if (i < ARRAY_SIZE (ppc64_standard_linkage12) - 1
 643           && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage12, insns))
 644         pc = ppc64_pcrel_linkage1_target (frame, insns, pc);
 645       else if (i < ARRAY_SIZE (ppc64_standard_linkage11) - 1
 646           && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage11, insns))
 647         pc = ppc64_pcrel_linkage2_target (frame, insns, pc);
 648       else if (i < ARRAY_SIZE (ppc64_standard_linkage10) - 1
 649           && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage10, insns))
 650         pc = ppc64_pcrel_linkage1_target (frame, insns, pc);
 651       else if (i < ARRAY_SIZE (ppc64_standard_linkage9) - 1
 652           && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage9, insns))
 653         pc = ppc64_pcrel_linkage1_target (frame, insns, pc);
 654       else if (i < ARRAY_SIZE (ppc64_standard_linkage8) - 1
 655           && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage8, insns))
 656         pc = ppc64_standard_linkage4_target (frame, insns);
 657       else if (i < ARRAY_SIZE (ppc64_standard_linkage7) - 1
 658                && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage7,
 659                                            insns))
 660         pc = ppc64_standard_linkage3_target (frame, insns);
 661       else if (i < ARRAY_SIZE (ppc64_standard_linkage6) - 1
 662                && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage6,
 663                                            insns))
 664         pc = ppc64_standard_linkage4_target (frame, insns);
 665       else if (i < ARRAY_SIZE (ppc64_standard_linkage5) - 1
 666                && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage5,
 667                                            insns)
 668                && (insns[8] != 0 || insns[9] != 0))
 669         pc = ppc64_standard_linkage3_target (frame, insns);
 670       else if (i < ARRAY_SIZE (ppc64_standard_linkage4) - 1
 671                && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage4,
 672                                            insns)
 673                && (insns[9] != 0 || insns[10] != 0))
 674         pc = ppc64_standard_linkage4_target (frame, insns);
 675       else if (i < ARRAY_SIZE (ppc64_standard_linkage3) - 1
 676                && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage3,
 677                                            insns)
 678                && (insns[8] != 0 || insns[9] != 0))
 679         pc = ppc64_standard_linkage3_target (frame, insns);
 680       else if (i < ARRAY_SIZE (ppc64_standard_linkage2) - 1
 681                && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage2,
 682                                            insns)
 683                && (insns[10] != 0 || insns[11] != 0))
 684         pc = ppc64_standard_linkage2_target (frame, insns);
 685       else if (i < ARRAY_SIZE (ppc64_standard_linkage1) - 1
 686                && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage1,
 687                                            insns))
 688         pc = ppc64_standard_linkage1_target (frame, insns);
 689       else
 690         {
 691           /* Scan backward one more instruction if it doesn't match.  */
 692           pc -= 4;
 693           continue;
 694         }
 695
 696       /* The PLT descriptor will either point to the already resolved target
 697          address, or else to a glink stub.  As the latter carry synthetic @plt
 698          symbols, find_solib_trampoline_target should be able to resolve them.  */
 699       target = find_solib_trampoline_target (frame, pc);
 700       return target ? target : pc;
 701   }
 702
 703   return 0;
 704 }
 705
 706 /* Wrapper of ppc64_skip_trampoline_code_1 checking also
 707    ppc_elfv2_skip_entrypoint.  */
 708
 709 CORE_ADDR
 710 ppc64_skip_trampoline_code (frame_info_ptr frame, CORE_ADDR pc)
 711 {
 712   struct gdbarch *gdbarch = get_frame_arch (frame);
 713
 714   pc = ppc64_skip_trampoline_code_1 (frame, pc);
 715   if (pc != 0 && gdbarch_skip_entrypoint_p (gdbarch))
 716     pc = gdbarch_skip_entrypoint (gdbarch, pc);
 717   return pc;
 718 }
 719
 720 /* Support for convert_from_func_ptr_addr (ARCH, ADDR, TARG) on PPC64
 721    GNU/Linux.
 722
 723    Usually a function pointer's representation is simply the address
 724    of the function.  On GNU/Linux on the PowerPC however, a function
 725    pointer may be a pointer to a function descriptor.
 726
 727    For PPC64, a function descriptor is a TOC entry, in a data section,
 728    which contains three words: the first word is the address of the
 729    function, the second word is the TOC pointer (r2), and the third word
 730    is the static chain value.
 731
 732    Throughout GDB it is currently assumed that a function pointer contains
 733    the address of the function, which is not easy to fix.  In addition, the
 734    conversion of a function address to a function pointer would
 735    require allocation of a TOC entry in the inferior's memory space,
 736    with all its drawbacks.  To be able to call C++ virtual methods in
 737    the inferior (which are called via function pointers),
 738    find_function_addr uses this function to get the function address
 739    from a function pointer.
 740
 741    If ADDR points at what is clearly a function descriptor, transform
 742    it into the address of the corresponding function, if needed.  Be
 743    conservative, otherwise GDB will do the transformation on any
 744    random addresses such as occur when there is no symbol table.  */
 745
 746 CORE_ADDR
 747 ppc64_convert_from_func_ptr_addr (struct gdbarch *gdbarch,
 748                                         CORE_ADDR addr,
 749                                         struct target_ops *targ)
 750 {
 751   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 752   const struct target_section *s = target_section_by_addr (targ, addr);
 753
 754   /* Check if ADDR points to a function descriptor.  */
 755   if (s && strcmp (s->the_bfd_section->name, ".opd") == 0)
 756     {
 757       /* There may be relocations that need to be applied to the .opd
 758          section.  Unfortunately, this function may be called at a time
 759          where these relocations have not yet been performed -- this can
 760          happen for example shortly after a library has been loaded with
 761          dlopen, but ld.so has not yet applied the relocations.
 762
 763          To cope with both the case where the relocation has been applied,
 764          and the case where it has not yet been applied, we do *not* read
 765          the (maybe) relocated value from target memory, but we instead
 766          read the non-relocated value from the BFD, and apply the relocation
 767          offset manually.
 768
 769          This makes the assumption that all .opd entries are always relocated
 770          by the same offset the section itself was relocated.  This should
 771          always be the case for GNU/Linux executables and shared libraries.
 772          Note that other kind of object files (e.g. those added via
 773          add-symbol-files) will currently never end up here anyway, as this
 774          function accesses *target* sections only; only the main exec and
 775          shared libraries are ever added to the target.  */
 776
 777       gdb_byte buf[8];
 778       int res;
 779
 780       res = bfd_get_section_contents (s->the_bfd_section->owner,
 781                                       s->the_bfd_section,
 782                                       &buf, addr - s->addr, 8);
 783       if (res != 0)
 784         return (extract_unsigned_integer (buf, 8, byte_order)
 785                 - bfd_section_vma (s->the_bfd_section) + s->addr);
 786    }
 787
 788   return addr;
 789 }
 790
 791 /* A synthetic 'dot' symbols on ppc64 has the udata.p entry pointing
 792    back to the original ELF symbol it was derived from.  Get the size
 793    from that symbol.  */
 794
 795 void
 796 ppc64_elf_make_msymbol_special (asymbol *sym, struct minimal_symbol *msym)
 797 {
 798   if ((sym->flags & BSF_SYNTHETIC) != 0 && sym->udata.p != NULL)
 799     {
 800       elf_symbol_type *elf_sym = (elf_symbol_type *) sym->udata.p;
 801       msym->set_size (elf_sym->internal_elf_sym.st_size);
 802     }
 803 }