1 /* Common target-dependent code for ppc64 GDB, the GNU debugger. 2 3 Copyright (C) 1986-2015 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 ((((opcd) & 0x3f) << 26) \ 34 | (((rts) & 0x1f) << 21) \ 35 | (((ra) & 0x1f) << 16) \ 36 | ((d) & 0xffff)) 37 38 #define insn_ds(opcd, rts, ra, d, xo) \ 39 ((((opcd) & 0x3f) << 26) \ 40 | (((rts) & 0x1f) << 21) \ 41 | (((ra) & 0x1f) << 16) \ 42 | ((d) & 0xfffc) \ 43 | ((xo) & 0x3)) 44 45 #define insn_xfx(opcd, rts, spr, xo) \ 46 ((((opcd) & 0x3f) << 26) \ 47 | (((rts) & 0x1f) << 21) \ 48 | (((spr) & 0x1f) << 16) \ 49 | (((spr) & 0x3e0) << 6) \ 50 | (((xo) & 0x3ff) << 1)) 51 52 /* If PLT is the address of a 64-bit PowerPC PLT entry, 53 return the function's entry point. */ 54 55 static CORE_ADDR 56 ppc64_plt_entry_point (struct gdbarch *gdbarch, CORE_ADDR plt) 57 { 58 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); 59 /* The first word of the PLT entry is the function entry point. */ 60 return (CORE_ADDR) read_memory_unsigned_integer (plt, 8, byte_order); 61 } 62 63 /* Patterns for the standard linkage functions. These are built by 64 build_plt_stub in bfd/elf64-ppc.c. */ 65 66 /* Old ELFv1 PLT call stub. */ 67 68 static struct ppc_insn_pattern ppc64_standard_linkage1[] = 69 { 70 /* addis r12, r2, <any> */ 71 { insn_d (-1, -1, -1, 0), insn_d (15, 12, 2, 0), 0 }, 72 73 /* std r2, 40(r1) */ 74 { -1, insn_ds (62, 2, 1, 40, 0), 0 }, 75 76 /* ld r11, <any>(r12) */ 77 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 12, 0, 0), 0 }, 78 79 /* addis r12, r12, 1 <optional> */ 80 { insn_d (-1, -1, -1, -1), insn_d (15, 12, 12, 1), 1 }, 81 82 /* ld r2, <any>(r12) */ 83 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 2, 12, 0, 0), 0 }, 84 85 /* addis r12, r12, 1 <optional> */ 86 { insn_d (-1, -1, -1, -1), insn_d (15, 12, 12, 1), 1 }, 87 88 /* mtctr r11 */ 89 { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 11, 9, 467), 0 }, 90 91 /* ld r11, <any>(r12) <optional> */ 92 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 12, 0, 0), 1 }, 93 94 /* bctr */ 95 { -1, 0x4e800420, 0 }, 96 97 { 0, 0, 0 } 98 }; 99 100 /* ELFv1 PLT call stub to access PLT entries more than +/- 32k from r2. 101 Also supports older stub with different placement of std 2,40(1), 102 a stub that omits the std 2,40(1), and both versions of power7 103 thread safety read barriers. Note that there are actually two more 104 instructions following "cmpldi r2, 0", "bnectr+" and "b <glink_i>", 105 but there isn't any need to match them. */ 106 107 static struct ppc_insn_pattern ppc64_standard_linkage2[] = 108 { 109 /* std r2, 40(r1) <optional> */ 110 { -1, insn_ds (62, 2, 1, 40, 0), 1 }, 111 112 /* addis r12, r2, <any> */ 113 { insn_d (-1, -1, -1, 0), insn_d (15, 12, 2, 0), 0 }, 114 115 /* std r2, 40(r1) <optional> */ 116 { -1, insn_ds (62, 2, 1, 40, 0), 1 }, 117 118 /* ld r11, <any>(r12) */ 119 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 12, 0, 0), 0 }, 120 121 /* addi r12, r12, <any> <optional> */ 122 { insn_d (-1, -1, -1, 0), insn_d (14, 12, 12, 0), 1 }, 123 124 /* mtctr r11 */ 125 { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 11, 9, 467), 0 }, 126 127 /* xor r11, r11, r11 <optional> */ 128 { -1, 0x7d6b5a78, 1 }, 129 130 /* add r12, r12, r11 <optional> */ 131 { -1, 0x7d8c5a14, 1 }, 132 133 /* ld r2, <any>(r12) */ 134 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 2, 12, 0, 0), 0 }, 135 136 /* ld r11, <any>(r12) <optional> */ 137 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 12, 0, 0), 1 }, 138 139 /* bctr <optional> */ 140 { -1, 0x4e800420, 1 }, 141 142 /* cmpldi r2, 0 <optional> */ 143 { -1, 0x28220000, 1 }, 144 145 { 0, 0, 0 } 146 }; 147 148 /* ELFv1 PLT call stub to access PLT entries within +/- 32k of r2. */ 149 150 static struct ppc_insn_pattern ppc64_standard_linkage3[] = 151 { 152 /* std r2, 40(r1) <optional> */ 153 { -1, insn_ds (62, 2, 1, 40, 0), 1 }, 154 155 /* ld r11, <any>(r2) */ 156 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 2, 0, 0), 0 }, 157 158 /* addi r2, r2, <any> <optional> */ 159 { insn_d (-1, -1, -1, 0), insn_d (14, 2, 2, 0), 1 }, 160 161 /* mtctr r11 */ 162 { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 11, 9, 467), 0 }, 163 164 /* xor r11, r11, r11 <optional> */ 165 { -1, 0x7d6b5a78, 1 }, 166 167 /* add r2, r2, r11 <optional> */ 168 { -1, 0x7c425a14, 1 }, 169 170 /* ld r11, <any>(r2) <optional> */ 171 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 2, 0, 0), 1 }, 172 173 /* ld r2, <any>(r2) */ 174 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 2, 2, 0, 0), 0 }, 175 176 /* bctr <optional> */ 177 { -1, 0x4e800420, 1 }, 178 179 /* cmpldi r2, 0 <optional> */ 180 { -1, 0x28220000, 1 }, 181 182 { 0, 0, 0 } 183 }; 184 185 /* ELFv1 PLT call stub to access PLT entries more than +/- 32k from r2. 186 A more modern variant of ppc64_standard_linkage2 differing in 187 register usage. */ 188 189 static struct ppc_insn_pattern ppc64_standard_linkage4[] = 190 { 191 /* std r2, 40(r1) <optional> */ 192 { -1, insn_ds (62, 2, 1, 40, 0), 1 }, 193 194 /* addis r11, r2, <any> */ 195 { insn_d (-1, -1, -1, 0), insn_d (15, 11, 2, 0), 0 }, 196 197 /* ld r12, <any>(r11) */ 198 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 12, 11, 0, 0), 0 }, 199 200 /* addi r11, r11, <any> <optional> */ 201 { insn_d (-1, -1, -1, 0), insn_d (14, 11, 11, 0), 1 }, 202 203 /* mtctr r12 */ 204 { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 }, 205 206 /* xor r2, r12, r12 <optional> */ 207 { -1, 0x7d826278, 1 }, 208 209 /* add r11, r11, r2 <optional> */ 210 { -1, 0x7d6b1214, 1 }, 211 212 /* ld r2, <any>(r11) */ 213 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 2, 11, 0, 0), 0 }, 214 215 /* ld r11, <any>(r11) <optional> */ 216 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 11, 0, 0), 1 }, 217 218 /* bctr <optional> */ 219 { -1, 0x4e800420, 1 }, 220 221 /* cmpldi r2, 0 <optional> */ 222 { -1, 0x28220000, 1 }, 223 224 { 0, 0, 0 } 225 }; 226 227 /* ELFv1 PLT call stub to access PLT entries within +/- 32k of r2. 228 A more modern variant of ppc64_standard_linkage3 differing in 229 register usage. */ 230 231 static struct ppc_insn_pattern ppc64_standard_linkage5[] = 232 { 233 /* std r2, 40(r1) <optional> */ 234 { -1, insn_ds (62, 2, 1, 40, 0), 1 }, 235 236 /* ld r12, <any>(r2) */ 237 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 12, 2, 0, 0), 0 }, 238 239 /* addi r2, r2, <any> <optional> */ 240 { insn_d (-1, -1, -1, 0), insn_d (14, 2, 2, 0), 1 }, 241 242 /* mtctr r12 */ 243 { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 }, 244 245 /* xor r11, r12, r12 <optional> */ 246 { -1, 0x7d8b6278, 1 }, 247 248 /* add r2, r2, r11 <optional> */ 249 { -1, 0x7c425a14, 1 }, 250 251 /* ld r11, <any>(r2) <optional> */ 252 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 2, 0, 0), 1 }, 253 254 /* ld r2, <any>(r2) */ 255 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 2, 2, 0, 0), 0 }, 256 257 /* bctr <optional> */ 258 { -1, 0x4e800420, 1 }, 259 260 /* cmpldi r2, 0 <optional> */ 261 { -1, 0x28220000, 1 }, 262 263 { 0, 0, 0 } 264 }; 265 266 /* ELFv2 PLT call stub to access PLT entries more than +/- 32k from r2. */ 267 268 static struct ppc_insn_pattern ppc64_standard_linkage6[] = 269 { 270 /* std r2, 24(r1) <optional> */ 271 { -1, insn_ds (62, 2, 1, 24, 0), 1 }, 272 273 /* addis r11, r2, <any> */ 274 { insn_d (-1, -1, -1, 0), insn_d (15, 11, 2, 0), 0 }, 275 276 /* ld r12, <any>(r11) */ 277 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 12, 11, 0, 0), 0 }, 278 279 /* mtctr r12 */ 280 { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 }, 281 282 /* bctr */ 283 { -1, 0x4e800420, 0 }, 284 285 { 0, 0, 0 } 286 }; 287 288 /* ELFv2 PLT call stub to access PLT entries within +/- 32k of r2. */ 289 290 static struct ppc_insn_pattern ppc64_standard_linkage7[] = 291 { 292 /* std r2, 24(r1) <optional> */ 293 { -1, insn_ds (62, 2, 1, 24, 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 /* mtctr r12 */ 299 { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 }, 300 301 /* bctr */ 302 { -1, 0x4e800420, 0 }, 303 304 { 0, 0, 0 } 305 }; 306 307 /* ELFv2 PLT call stub to access PLT entries more than +/- 32k from r2, 308 supporting fusion. */ 309 310 static struct ppc_insn_pattern ppc64_standard_linkage8[] = 311 { 312 /* std r2, 24(r1) <optional> */ 313 { -1, insn_ds (62, 2, 1, 24, 0), 1 }, 314 315 /* addis r12, r2, <any> */ 316 { insn_d (-1, -1, -1, 0), insn_d (15, 12, 2, 0), 0 }, 317 318 /* ld r12, <any>(r12) */ 319 { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 12, 12, 0, 0), 0 }, 320 321 /* mtctr r12 */ 322 { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 12, 9, 467), 0 }, 323 324 /* bctr */ 325 { -1, 0x4e800420, 0 }, 326 327 { 0, 0, 0 } 328 }; 329 330 /* When the dynamic linker is doing lazy symbol resolution, the first 331 call to a function in another object will go like this: 332 333 - The user's function calls the linkage function: 334 335 100003d4: 4b ff ff ad bl 10000380 <nnnn.plt_call.printf> 336 100003d8: e8 41 00 28 ld r2,40(r1) 337 338 - The linkage function loads the entry point and toc pointer from 339 the function descriptor in the PLT, and jumps to it: 340 341 <nnnn.plt_call.printf>: 342 10000380: f8 41 00 28 std r2,40(r1) 343 10000384: e9 62 80 78 ld r11,-32648(r2) 344 10000388: 7d 69 03 a6 mtctr r11 345 1000038c: e8 42 80 80 ld r2,-32640(r2) 346 10000390: 28 22 00 00 cmpldi r2,0 347 10000394: 4c e2 04 20 bnectr+ 348 10000398: 48 00 03 a0 b 10000738 <printf@plt> 349 350 - But since this is the first time that PLT entry has been used, it 351 sends control to its glink entry. That loads the number of the 352 PLT entry and jumps to the common glink0 code: 353 354 <printf@plt>: 355 10000738: 38 00 00 01 li r0,1 356 1000073c: 4b ff ff bc b 100006f8 <__glink_PLTresolve> 357 358 - The common glink0 code then transfers control to the dynamic 359 linker's fixup code: 360 361 100006f0: 0000000000010440 .quad plt0 - (. + 16) 362 <__glink_PLTresolve>: 363 100006f8: 7d 88 02 a6 mflr r12 364 100006fc: 42 9f 00 05 bcl 20,4*cr7+so,10000700 365 10000700: 7d 68 02 a6 mflr r11 366 10000704: e8 4b ff f0 ld r2,-16(r11) 367 10000708: 7d 88 03 a6 mtlr r12 368 1000070c: 7d 82 5a 14 add r12,r2,r11 369 10000710: e9 6c 00 00 ld r11,0(r12) 370 10000714: e8 4c 00 08 ld r2,8(r12) 371 10000718: 7d 69 03 a6 mtctr r11 372 1000071c: e9 6c 00 10 ld r11,16(r12) 373 10000720: 4e 80 04 20 bctr 374 375 Eventually, this code will figure out how to skip all of this, 376 including the dynamic linker. At the moment, we just get through 377 the linkage function. */ 378 379 /* If the current thread is about to execute a series of instructions 380 at PC matching the ppc64_standard_linkage pattern, and INSN is the result 381 from that pattern match, return the code address to which the 382 standard linkage function will send them. (This doesn't deal with 383 dynamic linker lazy symbol resolution stubs.) */ 384 385 static CORE_ADDR 386 ppc64_standard_linkage1_target (struct frame_info *frame, 387 CORE_ADDR pc, unsigned int *insn) 388 { 389 struct gdbarch *gdbarch = get_frame_arch (frame); 390 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); 391 392 /* The address of the PLT entry this linkage function references. */ 393 CORE_ADDR plt 394 = ((CORE_ADDR) get_frame_register_unsigned (frame, 395 tdep->ppc_gp0_regnum + 2) 396 + (ppc_insn_d_field (insn[0]) << 16) 397 + ppc_insn_ds_field (insn[2])); 398 399 return ppc64_plt_entry_point (gdbarch, plt); 400 } 401 402 static CORE_ADDR 403 ppc64_standard_linkage2_target (struct frame_info *frame, 404 CORE_ADDR pc, unsigned int *insn) 405 { 406 struct gdbarch *gdbarch = get_frame_arch (frame); 407 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); 408 409 /* The address of the PLT entry this linkage function references. */ 410 CORE_ADDR plt 411 = ((CORE_ADDR) get_frame_register_unsigned (frame, 412 tdep->ppc_gp0_regnum + 2) 413 + (ppc_insn_d_field (insn[1]) << 16) 414 + ppc_insn_ds_field (insn[3])); 415 416 return ppc64_plt_entry_point (gdbarch, plt); 417 } 418 419 static CORE_ADDR 420 ppc64_standard_linkage3_target (struct frame_info *frame, 421 CORE_ADDR pc, unsigned int *insn) 422 { 423 struct gdbarch *gdbarch = get_frame_arch (frame); 424 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); 425 426 /* The address of the PLT entry this linkage function references. */ 427 CORE_ADDR plt 428 = ((CORE_ADDR) get_frame_register_unsigned (frame, 429 tdep->ppc_gp0_regnum + 2) 430 + ppc_insn_ds_field (insn[1])); 431 432 return ppc64_plt_entry_point (gdbarch, plt); 433 } 434 435 static CORE_ADDR 436 ppc64_standard_linkage4_target (struct frame_info *frame, 437 CORE_ADDR pc, unsigned int *insn) 438 { 439 struct gdbarch *gdbarch = get_frame_arch (frame); 440 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); 441 442 CORE_ADDR plt 443 = ((CORE_ADDR) get_frame_register_unsigned (frame, tdep->ppc_gp0_regnum + 2) 444 + (ppc_insn_d_field (insn[1]) << 16) 445 + ppc_insn_ds_field (insn[2])); 446 447 return ppc64_plt_entry_point (gdbarch, plt); 448 } 449 450 451 /* Given that we've begun executing a call trampoline at PC, return 452 the entry point of the function the trampoline will go to. 453 454 When the execution direction is EXEC_REVERSE, scan backward to 455 check whether we are in the middle of a PLT stub. */ 456 457 CORE_ADDR 458 ppc64_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc) 459 { 460 #define MAX(a,b) ((a) > (b) ? (a) : (b)) 461 unsigned int insns[MAX (MAX (MAX (ARRAY_SIZE (ppc64_standard_linkage1), 462 ARRAY_SIZE (ppc64_standard_linkage2)), 463 MAX (ARRAY_SIZE (ppc64_standard_linkage3), 464 ARRAY_SIZE (ppc64_standard_linkage4))), 465 MAX (MAX (ARRAY_SIZE (ppc64_standard_linkage5), 466 ARRAY_SIZE (ppc64_standard_linkage6)), 467 MAX (ARRAY_SIZE (ppc64_standard_linkage7), 468 ARRAY_SIZE (ppc64_standard_linkage8)))) 469 - 1]; 470 CORE_ADDR target; 471 int scan_limit, i; 472 473 scan_limit = 1; 474 /* When reverse-debugging, scan backward to check whether we are 475 in the middle of trampoline code. */ 476 if (execution_direction == EXEC_REVERSE) 477 scan_limit = ARRAY_SIZE (insns) - 1; 478 479 for (i = 0; i < scan_limit; i++) 480 { 481 if (i < ARRAY_SIZE (ppc64_standard_linkage8) - 1 482 && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage8, insns)) 483 pc = ppc64_standard_linkage4_target (frame, pc, insns); 484 else if (i < ARRAY_SIZE (ppc64_standard_linkage7) - 1 485 && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage7, 486 insns)) 487 pc = ppc64_standard_linkage3_target (frame, pc, insns); 488 else if (i < ARRAY_SIZE (ppc64_standard_linkage6) - 1 489 && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage6, 490 insns)) 491 pc = ppc64_standard_linkage4_target (frame, pc, insns); 492 else if (i < ARRAY_SIZE (ppc64_standard_linkage5) - 1 493 && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage5, 494 insns) 495 && (insns[8] != 0 || insns[9] != 0)) 496 pc = ppc64_standard_linkage3_target (frame, pc, insns); 497 else if (i < ARRAY_SIZE (ppc64_standard_linkage4) - 1 498 && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage4, 499 insns) 500 && (insns[9] != 0 || insns[10] != 0)) 501 pc = ppc64_standard_linkage4_target (frame, pc, insns); 502 else if (i < ARRAY_SIZE (ppc64_standard_linkage3) - 1 503 && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage3, 504 insns) 505 && (insns[8] != 0 || insns[9] != 0)) 506 pc = ppc64_standard_linkage3_target (frame, pc, insns); 507 else if (i < ARRAY_SIZE (ppc64_standard_linkage2) - 1 508 && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage2, 509 insns) 510 && (insns[10] != 0 || insns[11] != 0)) 511 pc = ppc64_standard_linkage2_target (frame, pc, insns); 512 else if (i < ARRAY_SIZE (ppc64_standard_linkage1) - 1 513 && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage1, 514 insns)) 515 pc = ppc64_standard_linkage1_target (frame, pc, insns); 516 else 517 { 518 /* Scan backward one more instructions if doesn't match. */ 519 pc -= 4; 520 continue; 521 } 522 523 /* The PLT descriptor will either point to the already resolved target 524 address, or else to a glink stub. As the latter carry synthetic @plt 525 symbols, find_solib_trampoline_target should be able to resolve them. */ 526 target = find_solib_trampoline_target (frame, pc); 527 return target ? target : pc; 528 } 529 530 return 0; 531 } 532 533 /* Support for convert_from_func_ptr_addr (ARCH, ADDR, TARG) on PPC64 534 GNU/Linux. 535 536 Usually a function pointer's representation is simply the address 537 of the function. On GNU/Linux on the PowerPC however, a function 538 pointer may be a pointer to a function descriptor. 539 540 For PPC64, a function descriptor is a TOC entry, in a data section, 541 which contains three words: the first word is the address of the 542 function, the second word is the TOC pointer (r2), and the third word 543 is the static chain value. 544 545 Throughout GDB it is currently assumed that a function pointer contains 546 the address of the function, which is not easy to fix. In addition, the 547 conversion of a function address to a function pointer would 548 require allocation of a TOC entry in the inferior's memory space, 549 with all its drawbacks. To be able to call C++ virtual methods in 550 the inferior (which are called via function pointers), 551 find_function_addr uses this function to get the function address 552 from a function pointer. 553 554 If ADDR points at what is clearly a function descriptor, transform 555 it into the address of the corresponding function, if needed. Be 556 conservative, otherwise GDB will do the transformation on any 557 random addresses such as occur when there is no symbol table. */ 558 559 CORE_ADDR 560 ppc64_convert_from_func_ptr_addr (struct gdbarch *gdbarch, 561 CORE_ADDR addr, 562 struct target_ops *targ) 563 { 564 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); 565 struct target_section *s = target_section_by_addr (targ, addr); 566 567 /* Check if ADDR points to a function descriptor. */ 568 if (s && strcmp (s->the_bfd_section->name, ".opd") == 0) 569 { 570 /* There may be relocations that need to be applied to the .opd 571 section. Unfortunately, this function may be called at a time 572 where these relocations have not yet been performed -- this can 573 happen for example shortly after a library has been loaded with 574 dlopen, but ld.so has not yet applied the relocations. 575 576 To cope with both the case where the relocation has been applied, 577 and the case where it has not yet been applied, we do *not* read 578 the (maybe) relocated value from target memory, but we instead 579 read the non-relocated value from the BFD, and apply the relocation 580 offset manually. 581 582 This makes the assumption that all .opd entries are always relocated 583 by the same offset the section itself was relocated. This should 584 always be the case for GNU/Linux executables and shared libraries. 585 Note that other kind of object files (e.g. those added via 586 add-symbol-files) will currently never end up here anyway, as this 587 function accesses *target* sections only; only the main exec and 588 shared libraries are ever added to the target. */ 589 590 gdb_byte buf[8]; 591 int res; 592 593 res = bfd_get_section_contents (s->the_bfd_section->owner, 594 s->the_bfd_section, 595 &buf, addr - s->addr, 8); 596 if (res != 0) 597 return extract_unsigned_integer (buf, 8, byte_order) 598 - bfd_section_vma (s->bfd, s->the_bfd_section) + s->addr; 599 } 600 601 return addr; 602 } 603 604 /* A synthetic 'dot' symbols on ppc64 has the udata.p entry pointing 605 back to the original ELF symbol it was derived from. Get the size 606 from that symbol. */ 607 608 void 609 ppc64_elf_make_msymbol_special (asymbol *sym, struct minimal_symbol *msym) 610 { 611 if ((sym->flags & BSF_SYNTHETIC) != 0 && sym->udata.p != NULL) 612 { 613 elf_symbol_type *elf_sym = (elf_symbol_type *) sym->udata.p; 614 SET_MSYMBOL_SIZE (msym, elf_sym->internal_elf_sym.st_size); 615 } 616 } 617