1 /* Kernel module help for PPC64. 2 Copyright (C) 2001, 2003 Rusty Russell IBM Corporation. 3 4 This program is free software; you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 2 of the License, or 7 (at your option) any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program; if not, write to the Free Software 16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 17 */ 18 19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 20 21 #include <linux/module.h> 22 #include <linux/elf.h> 23 #include <linux/moduleloader.h> 24 #include <linux/err.h> 25 #include <linux/vmalloc.h> 26 #include <linux/ftrace.h> 27 #include <linux/bug.h> 28 #include <linux/uaccess.h> 29 #include <asm/module.h> 30 #include <asm/firmware.h> 31 #include <asm/code-patching.h> 32 #include <linux/sort.h> 33 #include <asm/setup.h> 34 #include <asm/sections.h> 35 36 /* FIXME: We don't do .init separately. To do this, we'd need to have 37 a separate r2 value in the init and core section, and stub between 38 them, too. 39 40 Using a magic allocator which places modules within 32MB solves 41 this, and makes other things simpler. Anton? 42 --RR. */ 43 44 #ifdef PPC64_ELF_ABI_v2 45 46 /* An address is simply the address of the function. */ 47 typedef unsigned long func_desc_t; 48 49 static func_desc_t func_desc(unsigned long addr) 50 { 51 return addr; 52 } 53 static unsigned long func_addr(unsigned long addr) 54 { 55 return addr; 56 } 57 static unsigned long stub_func_addr(func_desc_t func) 58 { 59 return func; 60 } 61 62 /* PowerPC64 specific values for the Elf64_Sym st_other field. */ 63 #define STO_PPC64_LOCAL_BIT 5 64 #define STO_PPC64_LOCAL_MASK (7 << STO_PPC64_LOCAL_BIT) 65 #define PPC64_LOCAL_ENTRY_OFFSET(other) \ 66 (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2) 67 68 static unsigned int local_entry_offset(const Elf64_Sym *sym) 69 { 70 /* sym->st_other indicates offset to local entry point 71 * (otherwise it will assume r12 is the address of the start 72 * of function and try to derive r2 from it). */ 73 return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other); 74 } 75 #else 76 77 /* An address is address of the OPD entry, which contains address of fn. */ 78 typedef struct ppc64_opd_entry func_desc_t; 79 80 static func_desc_t func_desc(unsigned long addr) 81 { 82 return *(struct ppc64_opd_entry *)addr; 83 } 84 static unsigned long func_addr(unsigned long addr) 85 { 86 return func_desc(addr).funcaddr; 87 } 88 static unsigned long stub_func_addr(func_desc_t func) 89 { 90 return func.funcaddr; 91 } 92 static unsigned int local_entry_offset(const Elf64_Sym *sym) 93 { 94 return 0; 95 } 96 #endif 97 98 #define STUB_MAGIC 0x73747562 /* stub */ 99 100 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into 101 the kernel itself). But on PPC64, these need to be used for every 102 jump, actually, to reset r2 (TOC+0x8000). */ 103 struct ppc64_stub_entry 104 { 105 /* 28 byte jump instruction sequence (7 instructions). We only 106 * need 6 instructions on ABIv2 but we always allocate 7 so 107 * so we don't have to modify the trampoline load instruction. */ 108 u32 jump[7]; 109 /* Used by ftrace to identify stubs */ 110 u32 magic; 111 /* Data for the above code */ 112 func_desc_t funcdata; 113 }; 114 115 /* 116 * PPC64 uses 24 bit jumps, but we need to jump into other modules or 117 * the kernel which may be further. So we jump to a stub. 118 * 119 * For ELFv1 we need to use this to set up the new r2 value (aka TOC 120 * pointer). For ELFv2 it's the callee's responsibility to set up the 121 * new r2, but for both we need to save the old r2. 122 * 123 * We could simply patch the new r2 value and function pointer into 124 * the stub, but it's significantly shorter to put these values at the 125 * end of the stub code, and patch the stub address (32-bits relative 126 * to the TOC ptr, r2) into the stub. 127 */ 128 129 static u32 ppc64_stub_insns[] = { 130 0x3d620000, /* addis r11,r2, <high> */ 131 0x396b0000, /* addi r11,r11, <low> */ 132 /* Save current r2 value in magic place on the stack. */ 133 0xf8410000|R2_STACK_OFFSET, /* std r2,R2_STACK_OFFSET(r1) */ 134 0xe98b0020, /* ld r12,32(r11) */ 135 #ifdef PPC64_ELF_ABI_v1 136 /* Set up new r2 from function descriptor */ 137 0xe84b0028, /* ld r2,40(r11) */ 138 #endif 139 0x7d8903a6, /* mtctr r12 */ 140 0x4e800420 /* bctr */ 141 }; 142 143 #ifdef CONFIG_DYNAMIC_FTRACE 144 int module_trampoline_target(struct module *mod, unsigned long addr, 145 unsigned long *target) 146 { 147 struct ppc64_stub_entry *stub; 148 func_desc_t funcdata; 149 u32 magic; 150 151 if (!within_module_core(addr, mod)) { 152 pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name); 153 return -EFAULT; 154 } 155 156 stub = (struct ppc64_stub_entry *)addr; 157 158 if (probe_kernel_read(&magic, &stub->magic, sizeof(magic))) { 159 pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name); 160 return -EFAULT; 161 } 162 163 if (magic != STUB_MAGIC) { 164 pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name); 165 return -EFAULT; 166 } 167 168 if (probe_kernel_read(&funcdata, &stub->funcdata, sizeof(funcdata))) { 169 pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name); 170 return -EFAULT; 171 } 172 173 *target = stub_func_addr(funcdata); 174 175 return 0; 176 } 177 #endif 178 179 /* Count how many different 24-bit relocations (different symbol, 180 different addend) */ 181 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num) 182 { 183 unsigned int i, r_info, r_addend, _count_relocs; 184 185 /* FIXME: Only count external ones --RR */ 186 _count_relocs = 0; 187 r_info = 0; 188 r_addend = 0; 189 for (i = 0; i < num; i++) 190 /* Only count 24-bit relocs, others don't need stubs */ 191 if (ELF64_R_TYPE(rela[i].r_info) == R_PPC_REL24 && 192 (r_info != ELF64_R_SYM(rela[i].r_info) || 193 r_addend != rela[i].r_addend)) { 194 _count_relocs++; 195 r_info = ELF64_R_SYM(rela[i].r_info); 196 r_addend = rela[i].r_addend; 197 } 198 199 return _count_relocs; 200 } 201 202 static int relacmp(const void *_x, const void *_y) 203 { 204 const Elf64_Rela *x, *y; 205 206 y = (Elf64_Rela *)_x; 207 x = (Elf64_Rela *)_y; 208 209 /* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to 210 * make the comparison cheaper/faster. It won't affect the sorting or 211 * the counting algorithms' performance 212 */ 213 if (x->r_info < y->r_info) 214 return -1; 215 else if (x->r_info > y->r_info) 216 return 1; 217 else if (x->r_addend < y->r_addend) 218 return -1; 219 else if (x->r_addend > y->r_addend) 220 return 1; 221 else 222 return 0; 223 } 224 225 static void relaswap(void *_x, void *_y, int size) 226 { 227 uint64_t *x, *y, tmp; 228 int i; 229 230 y = (uint64_t *)_x; 231 x = (uint64_t *)_y; 232 233 for (i = 0; i < sizeof(Elf64_Rela) / sizeof(uint64_t); i++) { 234 tmp = x[i]; 235 x[i] = y[i]; 236 y[i] = tmp; 237 } 238 } 239 240 /* Get size of potential trampolines required. */ 241 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr, 242 const Elf64_Shdr *sechdrs) 243 { 244 /* One extra reloc so it's always 0-funcaddr terminated */ 245 unsigned long relocs = 1; 246 unsigned i; 247 248 /* Every relocated section... */ 249 for (i = 1; i < hdr->e_shnum; i++) { 250 if (sechdrs[i].sh_type == SHT_RELA) { 251 pr_debug("Found relocations in section %u\n", i); 252 pr_debug("Ptr: %p. Number: %Lu\n", 253 (void *)sechdrs[i].sh_addr, 254 sechdrs[i].sh_size / sizeof(Elf64_Rela)); 255 256 /* Sort the relocation information based on a symbol and 257 * addend key. This is a stable O(n*log n) complexity 258 * alogrithm but it will reduce the complexity of 259 * count_relocs() to linear complexity O(n) 260 */ 261 sort((void *)sechdrs[i].sh_addr, 262 sechdrs[i].sh_size / sizeof(Elf64_Rela), 263 sizeof(Elf64_Rela), relacmp, relaswap); 264 265 relocs += count_relocs((void *)sechdrs[i].sh_addr, 266 sechdrs[i].sh_size 267 / sizeof(Elf64_Rela)); 268 } 269 } 270 271 #ifdef CONFIG_DYNAMIC_FTRACE 272 /* make the trampoline to the ftrace_caller */ 273 relocs++; 274 #endif 275 276 pr_debug("Looks like a total of %lu stubs, max\n", relocs); 277 return relocs * sizeof(struct ppc64_stub_entry); 278 } 279 280 /* Still needed for ELFv2, for .TOC. */ 281 static void dedotify_versions(struct modversion_info *vers, 282 unsigned long size) 283 { 284 struct modversion_info *end; 285 286 for (end = (void *)vers + size; vers < end; vers++) 287 if (vers->name[0] == '.') { 288 memmove(vers->name, vers->name+1, strlen(vers->name)); 289 #ifdef ARCH_RELOCATES_KCRCTAB 290 /* The TOC symbol has no CRC computed. To avoid CRC 291 * check failing, we must force it to the expected 292 * value (see CRC check in module.c). 293 */ 294 if (!strcmp(vers->name, "TOC.")) 295 vers->crc = -(unsigned long)reloc_start; 296 #endif 297 } 298 } 299 300 /* 301 * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC. 302 * seem to be defined (value set later). 303 */ 304 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab) 305 { 306 unsigned int i; 307 308 for (i = 1; i < numsyms; i++) { 309 if (syms[i].st_shndx == SHN_UNDEF) { 310 char *name = strtab + syms[i].st_name; 311 if (name[0] == '.') { 312 if (strcmp(name+1, "TOC.") == 0) 313 syms[i].st_shndx = SHN_ABS; 314 syms[i].st_name++; 315 } 316 } 317 } 318 } 319 320 static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs, 321 const char *strtab, 322 unsigned int symindex) 323 { 324 unsigned int i, numsyms; 325 Elf64_Sym *syms; 326 327 syms = (Elf64_Sym *)sechdrs[symindex].sh_addr; 328 numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym); 329 330 for (i = 1; i < numsyms; i++) { 331 if (syms[i].st_shndx == SHN_ABS 332 && strcmp(strtab + syms[i].st_name, "TOC.") == 0) 333 return &syms[i]; 334 } 335 return NULL; 336 } 337 338 int module_frob_arch_sections(Elf64_Ehdr *hdr, 339 Elf64_Shdr *sechdrs, 340 char *secstrings, 341 struct module *me) 342 { 343 unsigned int i; 344 345 /* Find .toc and .stubs sections, symtab and strtab */ 346 for (i = 1; i < hdr->e_shnum; i++) { 347 char *p; 348 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0) 349 me->arch.stubs_section = i; 350 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) 351 me->arch.toc_section = i; 352 else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0) 353 dedotify_versions((void *)hdr + sechdrs[i].sh_offset, 354 sechdrs[i].sh_size); 355 356 /* We don't handle .init for the moment: rename to _init */ 357 while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init"))) 358 p[0] = '_'; 359 360 if (sechdrs[i].sh_type == SHT_SYMTAB) 361 dedotify((void *)hdr + sechdrs[i].sh_offset, 362 sechdrs[i].sh_size / sizeof(Elf64_Sym), 363 (void *)hdr 364 + sechdrs[sechdrs[i].sh_link].sh_offset); 365 } 366 367 if (!me->arch.stubs_section) { 368 pr_err("%s: doesn't contain .stubs.\n", me->name); 369 return -ENOEXEC; 370 } 371 372 /* If we don't have a .toc, just use .stubs. We need to set r2 373 to some reasonable value in case the module calls out to 374 other functions via a stub, or if a function pointer escapes 375 the module by some means. */ 376 if (!me->arch.toc_section) 377 me->arch.toc_section = me->arch.stubs_section; 378 379 /* Override the stubs size */ 380 sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs); 381 return 0; 382 } 383 384 /* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this 385 gives the value maximum span in an instruction which uses a signed 386 offset) */ 387 static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me) 388 { 389 return sechdrs[me->arch.toc_section].sh_addr + 0x8000; 390 } 391 392 /* Both low and high 16 bits are added as SIGNED additions, so if low 393 16 bits has high bit set, high 16 bits must be adjusted. These 394 macros do that (stolen from binutils). */ 395 #define PPC_LO(v) ((v) & 0xffff) 396 #define PPC_HI(v) (((v) >> 16) & 0xffff) 397 #define PPC_HA(v) PPC_HI ((v) + 0x8000) 398 399 /* Patch stub to reference function and correct r2 value. */ 400 static inline int create_stub(const Elf64_Shdr *sechdrs, 401 struct ppc64_stub_entry *entry, 402 unsigned long addr, 403 struct module *me) 404 { 405 long reladdr; 406 407 memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns)); 408 409 /* Stub uses address relative to r2. */ 410 reladdr = (unsigned long)entry - my_r2(sechdrs, me); 411 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { 412 pr_err("%s: Address %p of stub out of range of %p.\n", 413 me->name, (void *)reladdr, (void *)my_r2); 414 return 0; 415 } 416 pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr); 417 418 entry->jump[0] |= PPC_HA(reladdr); 419 entry->jump[1] |= PPC_LO(reladdr); 420 entry->funcdata = func_desc(addr); 421 entry->magic = STUB_MAGIC; 422 423 return 1; 424 } 425 426 /* Create stub to jump to function described in this OPD/ptr: we need the 427 stub to set up the TOC ptr (r2) for the function. */ 428 static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs, 429 unsigned long addr, 430 struct module *me) 431 { 432 struct ppc64_stub_entry *stubs; 433 unsigned int i, num_stubs; 434 435 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs); 436 437 /* Find this stub, or if that fails, the next avail. entry */ 438 stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr; 439 for (i = 0; stub_func_addr(stubs[i].funcdata); i++) { 440 BUG_ON(i >= num_stubs); 441 442 if (stub_func_addr(stubs[i].funcdata) == func_addr(addr)) 443 return (unsigned long)&stubs[i]; 444 } 445 446 if (!create_stub(sechdrs, &stubs[i], addr, me)) 447 return 0; 448 449 return (unsigned long)&stubs[i]; 450 } 451 452 #ifdef CC_USING_MPROFILE_KERNEL 453 static bool is_early_mcount_callsite(u32 *instruction) 454 { 455 /* 456 * Check if this is one of the -mprofile-kernel sequences. 457 */ 458 if (instruction[-1] == PPC_INST_STD_LR && 459 instruction[-2] == PPC_INST_MFLR) 460 return true; 461 462 if (instruction[-1] == PPC_INST_MFLR) 463 return true; 464 465 return false; 466 } 467 468 /* 469 * In case of _mcount calls, do not save the current callee's TOC (in r2) into 470 * the original caller's stack frame. If we did we would clobber the saved TOC 471 * value of the original caller. 472 */ 473 static void squash_toc_save_inst(const char *name, unsigned long addr) 474 { 475 struct ppc64_stub_entry *stub = (struct ppc64_stub_entry *)addr; 476 477 /* Only for calls to _mcount */ 478 if (strcmp("_mcount", name) != 0) 479 return; 480 481 stub->jump[2] = PPC_INST_NOP; 482 } 483 #else 484 static void squash_toc_save_inst(const char *name, unsigned long addr) { } 485 486 /* without -mprofile-kernel, mcount calls are never early */ 487 static bool is_early_mcount_callsite(u32 *instruction) 488 { 489 return false; 490 } 491 #endif 492 493 /* We expect a noop next: if it is, replace it with instruction to 494 restore r2. */ 495 static int restore_r2(u32 *instruction, struct module *me) 496 { 497 if (*instruction != PPC_INST_NOP) { 498 if (is_early_mcount_callsite(instruction - 1)) 499 return 1; 500 pr_err("%s: Expect noop after relocate, got %08x\n", 501 me->name, *instruction); 502 return 0; 503 } 504 /* ld r2,R2_STACK_OFFSET(r1) */ 505 *instruction = PPC_INST_LD_TOC; 506 return 1; 507 } 508 509 int apply_relocate_add(Elf64_Shdr *sechdrs, 510 const char *strtab, 511 unsigned int symindex, 512 unsigned int relsec, 513 struct module *me) 514 { 515 unsigned int i; 516 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr; 517 Elf64_Sym *sym; 518 unsigned long *location; 519 unsigned long value; 520 521 pr_debug("Applying ADD relocate section %u to %u\n", relsec, 522 sechdrs[relsec].sh_info); 523 524 /* First time we're called, we can fix up .TOC. */ 525 if (!me->arch.toc_fixed) { 526 sym = find_dot_toc(sechdrs, strtab, symindex); 527 /* It's theoretically possible that a module doesn't want a 528 * .TOC. so don't fail it just for that. */ 529 if (sym) 530 sym->st_value = my_r2(sechdrs, me); 531 me->arch.toc_fixed = true; 532 } 533 534 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { 535 /* This is where to make the change */ 536 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 537 + rela[i].r_offset; 538 /* This is the symbol it is referring to */ 539 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr 540 + ELF64_R_SYM(rela[i].r_info); 541 542 pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n", 543 location, (long)ELF64_R_TYPE(rela[i].r_info), 544 strtab + sym->st_name, (unsigned long)sym->st_value, 545 (long)rela[i].r_addend); 546 547 /* `Everything is relative'. */ 548 value = sym->st_value + rela[i].r_addend; 549 550 switch (ELF64_R_TYPE(rela[i].r_info)) { 551 case R_PPC64_ADDR32: 552 /* Simply set it */ 553 *(u32 *)location = value; 554 break; 555 556 case R_PPC64_ADDR64: 557 /* Simply set it */ 558 *(unsigned long *)location = value; 559 break; 560 561 case R_PPC64_TOC: 562 *(unsigned long *)location = my_r2(sechdrs, me); 563 break; 564 565 case R_PPC64_TOC16: 566 /* Subtract TOC pointer */ 567 value -= my_r2(sechdrs, me); 568 if (value + 0x8000 > 0xffff) { 569 pr_err("%s: bad TOC16 relocation (0x%lx)\n", 570 me->name, value); 571 return -ENOEXEC; 572 } 573 *((uint16_t *) location) 574 = (*((uint16_t *) location) & ~0xffff) 575 | (value & 0xffff); 576 break; 577 578 case R_PPC64_TOC16_LO: 579 /* Subtract TOC pointer */ 580 value -= my_r2(sechdrs, me); 581 *((uint16_t *) location) 582 = (*((uint16_t *) location) & ~0xffff) 583 | (value & 0xffff); 584 break; 585 586 case R_PPC64_TOC16_DS: 587 /* Subtract TOC pointer */ 588 value -= my_r2(sechdrs, me); 589 if ((value & 3) != 0 || value + 0x8000 > 0xffff) { 590 pr_err("%s: bad TOC16_DS relocation (0x%lx)\n", 591 me->name, value); 592 return -ENOEXEC; 593 } 594 *((uint16_t *) location) 595 = (*((uint16_t *) location) & ~0xfffc) 596 | (value & 0xfffc); 597 break; 598 599 case R_PPC64_TOC16_LO_DS: 600 /* Subtract TOC pointer */ 601 value -= my_r2(sechdrs, me); 602 if ((value & 3) != 0) { 603 pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n", 604 me->name, value); 605 return -ENOEXEC; 606 } 607 *((uint16_t *) location) 608 = (*((uint16_t *) location) & ~0xfffc) 609 | (value & 0xfffc); 610 break; 611 612 case R_PPC64_TOC16_HA: 613 /* Subtract TOC pointer */ 614 value -= my_r2(sechdrs, me); 615 value = ((value + 0x8000) >> 16); 616 *((uint16_t *) location) 617 = (*((uint16_t *) location) & ~0xffff) 618 | (value & 0xffff); 619 break; 620 621 case R_PPC_REL24: 622 /* FIXME: Handle weak symbols here --RR */ 623 if (sym->st_shndx == SHN_UNDEF) { 624 /* External: go via stub */ 625 value = stub_for_addr(sechdrs, value, me); 626 if (!value) 627 return -ENOENT; 628 if (!restore_r2((u32 *)location + 1, me)) 629 return -ENOEXEC; 630 631 squash_toc_save_inst(strtab + sym->st_name, value); 632 } else 633 value += local_entry_offset(sym); 634 635 /* Convert value to relative */ 636 value -= (unsigned long)location; 637 if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){ 638 pr_err("%s: REL24 %li out of range!\n", 639 me->name, (long int)value); 640 return -ENOEXEC; 641 } 642 643 /* Only replace bits 2 through 26 */ 644 *(uint32_t *)location 645 = (*(uint32_t *)location & ~0x03fffffc) 646 | (value & 0x03fffffc); 647 break; 648 649 case R_PPC64_REL64: 650 /* 64 bits relative (used by features fixups) */ 651 *location = value - (unsigned long)location; 652 break; 653 654 case R_PPC64_TOCSAVE: 655 /* 656 * Marker reloc indicates we don't have to save r2. 657 * That would only save us one instruction, so ignore 658 * it. 659 */ 660 break; 661 662 case R_PPC64_ENTRY: 663 /* 664 * Optimize ELFv2 large code model entry point if 665 * the TOC is within 2GB range of current location. 666 */ 667 value = my_r2(sechdrs, me) - (unsigned long)location; 668 if (value + 0x80008000 > 0xffffffff) 669 break; 670 /* 671 * Check for the large code model prolog sequence: 672 * ld r2, ...(r12) 673 * add r2, r2, r12 674 */ 675 if ((((uint32_t *)location)[0] & ~0xfffc) 676 != 0xe84c0000) 677 break; 678 if (((uint32_t *)location)[1] != 0x7c426214) 679 break; 680 /* 681 * If found, replace it with: 682 * addis r2, r12, (.TOC.-func)@ha 683 * addi r2, r12, (.TOC.-func)@l 684 */ 685 ((uint32_t *)location)[0] = 0x3c4c0000 + PPC_HA(value); 686 ((uint32_t *)location)[1] = 0x38420000 + PPC_LO(value); 687 break; 688 689 case R_PPC64_REL16_HA: 690 /* Subtract location pointer */ 691 value -= (unsigned long)location; 692 value = ((value + 0x8000) >> 16); 693 *((uint16_t *) location) 694 = (*((uint16_t *) location) & ~0xffff) 695 | (value & 0xffff); 696 break; 697 698 case R_PPC64_REL16_LO: 699 /* Subtract location pointer */ 700 value -= (unsigned long)location; 701 *((uint16_t *) location) 702 = (*((uint16_t *) location) & ~0xffff) 703 | (value & 0xffff); 704 break; 705 706 default: 707 pr_err("%s: Unknown ADD relocation: %lu\n", 708 me->name, 709 (unsigned long)ELF64_R_TYPE(rela[i].r_info)); 710 return -ENOEXEC; 711 } 712 } 713 714 return 0; 715 } 716 717 #ifdef CONFIG_DYNAMIC_FTRACE 718 719 #ifdef CC_USING_MPROFILE_KERNEL 720 721 #define PACATOC offsetof(struct paca_struct, kernel_toc) 722 723 /* 724 * For mprofile-kernel we use a special stub for ftrace_caller() because we 725 * can't rely on r2 containing this module's TOC when we enter the stub. 726 * 727 * That can happen if the function calling us didn't need to use the toc. In 728 * that case it won't have setup r2, and the r2 value will be either the 729 * kernel's toc, or possibly another modules toc. 730 * 731 * To deal with that this stub uses the kernel toc, which is always accessible 732 * via the paca (in r13). The target (ftrace_caller()) is responsible for 733 * saving and restoring the toc before returning. 734 */ 735 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me) 736 { 737 struct ppc64_stub_entry *entry; 738 unsigned int i, num_stubs; 739 static u32 stub_insns[] = { 740 0xe98d0000 | PACATOC, /* ld r12,PACATOC(r13) */ 741 0x3d8c0000, /* addis r12,r12,<high> */ 742 0x398c0000, /* addi r12,r12,<low> */ 743 0x7d8903a6, /* mtctr r12 */ 744 0x4e800420, /* bctr */ 745 }; 746 long reladdr; 747 748 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*entry); 749 750 /* Find the next available stub entry */ 751 entry = (void *)sechdrs[me->arch.stubs_section].sh_addr; 752 for (i = 0; i < num_stubs && stub_func_addr(entry->funcdata); i++, entry++); 753 754 if (i >= num_stubs) { 755 pr_err("%s: Unable to find a free slot for ftrace stub.\n", me->name); 756 return 0; 757 } 758 759 memcpy(entry->jump, stub_insns, sizeof(stub_insns)); 760 761 /* Stub uses address relative to kernel toc (from the paca) */ 762 reladdr = (unsigned long)ftrace_caller - kernel_toc_addr(); 763 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { 764 pr_err("%s: Address of ftrace_caller out of range of kernel_toc.\n", me->name); 765 return 0; 766 } 767 768 entry->jump[1] |= PPC_HA(reladdr); 769 entry->jump[2] |= PPC_LO(reladdr); 770 771 /* Eventhough we don't use funcdata in the stub, it's needed elsewhere. */ 772 entry->funcdata = func_desc((unsigned long)ftrace_caller); 773 entry->magic = STUB_MAGIC; 774 775 return (unsigned long)entry; 776 } 777 #else 778 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me) 779 { 780 return stub_for_addr(sechdrs, (unsigned long)ftrace_caller, me); 781 } 782 #endif 783 784 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs) 785 { 786 mod->arch.toc = my_r2(sechdrs, mod); 787 mod->arch.tramp = create_ftrace_stub(sechdrs, mod); 788 789 if (!mod->arch.tramp) 790 return -ENOENT; 791 792 return 0; 793 } 794 #endif 795