1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Kernel module help for PPC64. 3 Copyright (C) 2001, 2003 Rusty Russell IBM Corporation. 4 5 */ 6 7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 8 9 #include <linux/module.h> 10 #include <linux/elf.h> 11 #include <linux/moduleloader.h> 12 #include <linux/err.h> 13 #include <linux/vmalloc.h> 14 #include <linux/ftrace.h> 15 #include <linux/bug.h> 16 #include <linux/uaccess.h> 17 #include <asm/module.h> 18 #include <asm/firmware.h> 19 #include <asm/code-patching.h> 20 #include <linux/sort.h> 21 #include <asm/setup.h> 22 #include <asm/sections.h> 23 24 /* FIXME: We don't do .init separately. To do this, we'd need to have 25 a separate r2 value in the init and core section, and stub between 26 them, too. 27 28 Using a magic allocator which places modules within 32MB solves 29 this, and makes other things simpler. Anton? 30 --RR. */ 31 32 #ifdef PPC64_ELF_ABI_v2 33 34 /* An address is simply the address of the function. */ 35 typedef unsigned long func_desc_t; 36 37 static func_desc_t func_desc(unsigned long addr) 38 { 39 return addr; 40 } 41 static unsigned long func_addr(unsigned long addr) 42 { 43 return addr; 44 } 45 static unsigned long stub_func_addr(func_desc_t func) 46 { 47 return func; 48 } 49 50 /* PowerPC64 specific values for the Elf64_Sym st_other field. */ 51 #define STO_PPC64_LOCAL_BIT 5 52 #define STO_PPC64_LOCAL_MASK (7 << STO_PPC64_LOCAL_BIT) 53 #define PPC64_LOCAL_ENTRY_OFFSET(other) \ 54 (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2) 55 56 static unsigned int local_entry_offset(const Elf64_Sym *sym) 57 { 58 /* sym->st_other indicates offset to local entry point 59 * (otherwise it will assume r12 is the address of the start 60 * of function and try to derive r2 from it). */ 61 return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other); 62 } 63 #else 64 65 /* An address is address of the OPD entry, which contains address of fn. */ 66 typedef struct ppc64_opd_entry func_desc_t; 67 68 static func_desc_t func_desc(unsigned long addr) 69 { 70 return *(struct ppc64_opd_entry *)addr; 71 } 72 static unsigned long func_addr(unsigned long addr) 73 { 74 return func_desc(addr).funcaddr; 75 } 76 static unsigned long stub_func_addr(func_desc_t func) 77 { 78 return func.funcaddr; 79 } 80 static unsigned int local_entry_offset(const Elf64_Sym *sym) 81 { 82 return 0; 83 } 84 85 void *dereference_module_function_descriptor(struct module *mod, void *ptr) 86 { 87 if (ptr < (void *)mod->arch.start_opd || 88 ptr >= (void *)mod->arch.end_opd) 89 return ptr; 90 91 return dereference_function_descriptor(ptr); 92 } 93 #endif 94 95 #define STUB_MAGIC 0x73747562 /* stub */ 96 97 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into 98 the kernel itself). But on PPC64, these need to be used for every 99 jump, actually, to reset r2 (TOC+0x8000). */ 100 struct ppc64_stub_entry 101 { 102 /* 28 byte jump instruction sequence (7 instructions). We only 103 * need 6 instructions on ABIv2 but we always allocate 7 so 104 * so we don't have to modify the trampoline load instruction. */ 105 u32 jump[7]; 106 /* Used by ftrace to identify stubs */ 107 u32 magic; 108 /* Data for the above code */ 109 func_desc_t funcdata; 110 }; 111 112 /* 113 * PPC64 uses 24 bit jumps, but we need to jump into other modules or 114 * the kernel which may be further. So we jump to a stub. 115 * 116 * For ELFv1 we need to use this to set up the new r2 value (aka TOC 117 * pointer). For ELFv2 it's the callee's responsibility to set up the 118 * new r2, but for both we need to save the old r2. 119 * 120 * We could simply patch the new r2 value and function pointer into 121 * the stub, but it's significantly shorter to put these values at the 122 * end of the stub code, and patch the stub address (32-bits relative 123 * to the TOC ptr, r2) into the stub. 124 */ 125 126 static u32 ppc64_stub_insns[] = { 127 0x3d620000, /* addis r11,r2, <high> */ 128 0x396b0000, /* addi r11,r11, <low> */ 129 /* Save current r2 value in magic place on the stack. */ 130 0xf8410000|R2_STACK_OFFSET, /* std r2,R2_STACK_OFFSET(r1) */ 131 0xe98b0020, /* ld r12,32(r11) */ 132 #ifdef PPC64_ELF_ABI_v1 133 /* Set up new r2 from function descriptor */ 134 0xe84b0028, /* ld r2,40(r11) */ 135 #endif 136 0x7d8903a6, /* mtctr r12 */ 137 0x4e800420 /* bctr */ 138 }; 139 140 #ifdef CONFIG_DYNAMIC_FTRACE 141 int module_trampoline_target(struct module *mod, unsigned long addr, 142 unsigned long *target) 143 { 144 struct ppc64_stub_entry *stub; 145 func_desc_t funcdata; 146 u32 magic; 147 148 if (!within_module_core(addr, mod)) { 149 pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name); 150 return -EFAULT; 151 } 152 153 stub = (struct ppc64_stub_entry *)addr; 154 155 if (probe_kernel_read(&magic, &stub->magic, sizeof(magic))) { 156 pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name); 157 return -EFAULT; 158 } 159 160 if (magic != STUB_MAGIC) { 161 pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name); 162 return -EFAULT; 163 } 164 165 if (probe_kernel_read(&funcdata, &stub->funcdata, sizeof(funcdata))) { 166 pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name); 167 return -EFAULT; 168 } 169 170 *target = stub_func_addr(funcdata); 171 172 return 0; 173 } 174 #endif 175 176 /* Count how many different 24-bit relocations (different symbol, 177 different addend) */ 178 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num) 179 { 180 unsigned int i, r_info, r_addend, _count_relocs; 181 182 /* FIXME: Only count external ones --RR */ 183 _count_relocs = 0; 184 r_info = 0; 185 r_addend = 0; 186 for (i = 0; i < num; i++) 187 /* Only count 24-bit relocs, others don't need stubs */ 188 if (ELF64_R_TYPE(rela[i].r_info) == R_PPC_REL24 && 189 (r_info != ELF64_R_SYM(rela[i].r_info) || 190 r_addend != rela[i].r_addend)) { 191 _count_relocs++; 192 r_info = ELF64_R_SYM(rela[i].r_info); 193 r_addend = rela[i].r_addend; 194 } 195 196 return _count_relocs; 197 } 198 199 static int relacmp(const void *_x, const void *_y) 200 { 201 const Elf64_Rela *x, *y; 202 203 y = (Elf64_Rela *)_x; 204 x = (Elf64_Rela *)_y; 205 206 /* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to 207 * make the comparison cheaper/faster. It won't affect the sorting or 208 * the counting algorithms' performance 209 */ 210 if (x->r_info < y->r_info) 211 return -1; 212 else if (x->r_info > y->r_info) 213 return 1; 214 else if (x->r_addend < y->r_addend) 215 return -1; 216 else if (x->r_addend > y->r_addend) 217 return 1; 218 else 219 return 0; 220 } 221 222 static void relaswap(void *_x, void *_y, int size) 223 { 224 uint64_t *x, *y, tmp; 225 int i; 226 227 y = (uint64_t *)_x; 228 x = (uint64_t *)_y; 229 230 for (i = 0; i < sizeof(Elf64_Rela) / sizeof(uint64_t); i++) { 231 tmp = x[i]; 232 x[i] = y[i]; 233 y[i] = tmp; 234 } 235 } 236 237 /* Get size of potential trampolines required. */ 238 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr, 239 const Elf64_Shdr *sechdrs) 240 { 241 /* One extra reloc so it's always 0-funcaddr terminated */ 242 unsigned long relocs = 1; 243 unsigned i; 244 245 /* Every relocated section... */ 246 for (i = 1; i < hdr->e_shnum; i++) { 247 if (sechdrs[i].sh_type == SHT_RELA) { 248 pr_debug("Found relocations in section %u\n", i); 249 pr_debug("Ptr: %p. Number: %Lu\n", 250 (void *)sechdrs[i].sh_addr, 251 sechdrs[i].sh_size / sizeof(Elf64_Rela)); 252 253 /* Sort the relocation information based on a symbol and 254 * addend key. This is a stable O(n*log n) complexity 255 * alogrithm but it will reduce the complexity of 256 * count_relocs() to linear complexity O(n) 257 */ 258 sort((void *)sechdrs[i].sh_addr, 259 sechdrs[i].sh_size / sizeof(Elf64_Rela), 260 sizeof(Elf64_Rela), relacmp, relaswap); 261 262 relocs += count_relocs((void *)sechdrs[i].sh_addr, 263 sechdrs[i].sh_size 264 / sizeof(Elf64_Rela)); 265 } 266 } 267 268 #ifdef CONFIG_DYNAMIC_FTRACE 269 /* make the trampoline to the ftrace_caller */ 270 relocs++; 271 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS 272 /* an additional one for ftrace_regs_caller */ 273 relocs++; 274 #endif 275 #endif 276 277 pr_debug("Looks like a total of %lu stubs, max\n", relocs); 278 return relocs * sizeof(struct ppc64_stub_entry); 279 } 280 281 /* Still needed for ELFv2, for .TOC. */ 282 static void dedotify_versions(struct modversion_info *vers, 283 unsigned long size) 284 { 285 struct modversion_info *end; 286 287 for (end = (void *)vers + size; vers < end; vers++) 288 if (vers->name[0] == '.') { 289 memmove(vers->name, vers->name+1, strlen(vers->name)); 290 } 291 } 292 293 /* 294 * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC. 295 * seem to be defined (value set later). 296 */ 297 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab) 298 { 299 unsigned int i; 300 301 for (i = 1; i < numsyms; i++) { 302 if (syms[i].st_shndx == SHN_UNDEF) { 303 char *name = strtab + syms[i].st_name; 304 if (name[0] == '.') { 305 if (strcmp(name+1, "TOC.") == 0) 306 syms[i].st_shndx = SHN_ABS; 307 syms[i].st_name++; 308 } 309 } 310 } 311 } 312 313 static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs, 314 const char *strtab, 315 unsigned int symindex) 316 { 317 unsigned int i, numsyms; 318 Elf64_Sym *syms; 319 320 syms = (Elf64_Sym *)sechdrs[symindex].sh_addr; 321 numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym); 322 323 for (i = 1; i < numsyms; i++) { 324 if (syms[i].st_shndx == SHN_ABS 325 && strcmp(strtab + syms[i].st_name, "TOC.") == 0) 326 return &syms[i]; 327 } 328 return NULL; 329 } 330 331 int module_frob_arch_sections(Elf64_Ehdr *hdr, 332 Elf64_Shdr *sechdrs, 333 char *secstrings, 334 struct module *me) 335 { 336 unsigned int i; 337 338 /* Find .toc and .stubs sections, symtab and strtab */ 339 for (i = 1; i < hdr->e_shnum; i++) { 340 char *p; 341 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0) 342 me->arch.stubs_section = i; 343 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) { 344 me->arch.toc_section = i; 345 if (sechdrs[i].sh_addralign < 8) 346 sechdrs[i].sh_addralign = 8; 347 } 348 else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0) 349 dedotify_versions((void *)hdr + sechdrs[i].sh_offset, 350 sechdrs[i].sh_size); 351 352 /* We don't handle .init for the moment: rename to _init */ 353 while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init"))) 354 p[0] = '_'; 355 356 if (sechdrs[i].sh_type == SHT_SYMTAB) 357 dedotify((void *)hdr + sechdrs[i].sh_offset, 358 sechdrs[i].sh_size / sizeof(Elf64_Sym), 359 (void *)hdr 360 + sechdrs[sechdrs[i].sh_link].sh_offset); 361 } 362 363 if (!me->arch.stubs_section) { 364 pr_err("%s: doesn't contain .stubs.\n", me->name); 365 return -ENOEXEC; 366 } 367 368 /* If we don't have a .toc, just use .stubs. We need to set r2 369 to some reasonable value in case the module calls out to 370 other functions via a stub, or if a function pointer escapes 371 the module by some means. */ 372 if (!me->arch.toc_section) 373 me->arch.toc_section = me->arch.stubs_section; 374 375 /* Override the stubs size */ 376 sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs); 377 return 0; 378 } 379 380 /* 381 * r2 is the TOC pointer: it actually points 0x8000 into the TOC (this gives the 382 * value maximum span in an instruction which uses a signed offset). Round down 383 * to a 256 byte boundary for the odd case where we are setting up r2 without a 384 * .toc section. 385 */ 386 static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me) 387 { 388 return (sechdrs[me->arch.toc_section].sh_addr & ~0xfful) + 0x8000; 389 } 390 391 /* Both low and high 16 bits are added as SIGNED additions, so if low 392 16 bits has high bit set, high 16 bits must be adjusted. These 393 macros do that (stolen from binutils). */ 394 #define PPC_LO(v) ((v) & 0xffff) 395 #define PPC_HI(v) (((v) >> 16) & 0xffff) 396 #define PPC_HA(v) PPC_HI ((v) + 0x8000) 397 398 /* Patch stub to reference function and correct r2 value. */ 399 static inline int create_stub(const Elf64_Shdr *sechdrs, 400 struct ppc64_stub_entry *entry, 401 unsigned long addr, 402 struct module *me) 403 { 404 long reladdr; 405 406 memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns)); 407 408 /* Stub uses address relative to r2. */ 409 reladdr = (unsigned long)entry - my_r2(sechdrs, me); 410 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { 411 pr_err("%s: Address %p of stub out of range of %p.\n", 412 me->name, (void *)reladdr, (void *)my_r2); 413 return 0; 414 } 415 pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr); 416 417 entry->jump[0] |= PPC_HA(reladdr); 418 entry->jump[1] |= PPC_LO(reladdr); 419 entry->funcdata = func_desc(addr); 420 entry->magic = STUB_MAGIC; 421 422 return 1; 423 } 424 425 /* Create stub to jump to function described in this OPD/ptr: we need the 426 stub to set up the TOC ptr (r2) for the function. */ 427 static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs, 428 unsigned long addr, 429 struct module *me) 430 { 431 struct ppc64_stub_entry *stubs; 432 unsigned int i, num_stubs; 433 434 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs); 435 436 /* Find this stub, or if that fails, the next avail. entry */ 437 stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr; 438 for (i = 0; stub_func_addr(stubs[i].funcdata); i++) { 439 if (WARN_ON(i >= num_stubs)) 440 return 0; 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 CONFIG_MPROFILE_KERNEL 453 static bool is_mprofile_mcount_callsite(const char *name, u32 *instruction) 454 { 455 if (strcmp("_mcount", name)) 456 return false; 457 458 /* 459 * Check if this is one of the -mprofile-kernel sequences. 460 */ 461 if (instruction[-1] == PPC_INST_STD_LR && 462 instruction[-2] == PPC_INST_MFLR) 463 return true; 464 465 if (instruction[-1] == PPC_INST_MFLR) 466 return true; 467 468 return false; 469 } 470 471 /* 472 * In case of _mcount calls, do not save the current callee's TOC (in r2) into 473 * the original caller's stack frame. If we did we would clobber the saved TOC 474 * value of the original caller. 475 */ 476 static void squash_toc_save_inst(const char *name, unsigned long addr) 477 { 478 struct ppc64_stub_entry *stub = (struct ppc64_stub_entry *)addr; 479 480 /* Only for calls to _mcount */ 481 if (strcmp("_mcount", name) != 0) 482 return; 483 484 stub->jump[2] = PPC_INST_NOP; 485 } 486 #else 487 static void squash_toc_save_inst(const char *name, unsigned long addr) { } 488 489 static bool is_mprofile_mcount_callsite(const char *name, u32 *instruction) 490 { 491 return false; 492 } 493 #endif 494 495 /* We expect a noop next: if it is, replace it with instruction to 496 restore r2. */ 497 static int restore_r2(const char *name, u32 *instruction, struct module *me) 498 { 499 u32 *prev_insn = instruction - 1; 500 501 if (is_mprofile_mcount_callsite(name, prev_insn)) 502 return 1; 503 504 /* 505 * Make sure the branch isn't a sibling call. Sibling calls aren't 506 * "link" branches and they don't return, so they don't need the r2 507 * restore afterwards. 508 */ 509 if (!instr_is_relative_link_branch(*prev_insn)) 510 return 1; 511 512 if (*instruction != PPC_INST_NOP) { 513 pr_err("%s: Expected nop after call, got %08x at %pS\n", 514 me->name, *instruction, instruction); 515 return 0; 516 } 517 /* ld r2,R2_STACK_OFFSET(r1) */ 518 *instruction = PPC_INST_LD_TOC; 519 return 1; 520 } 521 522 int apply_relocate_add(Elf64_Shdr *sechdrs, 523 const char *strtab, 524 unsigned int symindex, 525 unsigned int relsec, 526 struct module *me) 527 { 528 unsigned int i; 529 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr; 530 Elf64_Sym *sym; 531 unsigned long *location; 532 unsigned long value; 533 534 pr_debug("Applying ADD relocate section %u to %u\n", relsec, 535 sechdrs[relsec].sh_info); 536 537 /* First time we're called, we can fix up .TOC. */ 538 if (!me->arch.toc_fixed) { 539 sym = find_dot_toc(sechdrs, strtab, symindex); 540 /* It's theoretically possible that a module doesn't want a 541 * .TOC. so don't fail it just for that. */ 542 if (sym) 543 sym->st_value = my_r2(sechdrs, me); 544 me->arch.toc_fixed = true; 545 } 546 547 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { 548 /* This is where to make the change */ 549 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 550 + rela[i].r_offset; 551 /* This is the symbol it is referring to */ 552 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr 553 + ELF64_R_SYM(rela[i].r_info); 554 555 pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n", 556 location, (long)ELF64_R_TYPE(rela[i].r_info), 557 strtab + sym->st_name, (unsigned long)sym->st_value, 558 (long)rela[i].r_addend); 559 560 /* `Everything is relative'. */ 561 value = sym->st_value + rela[i].r_addend; 562 563 switch (ELF64_R_TYPE(rela[i].r_info)) { 564 case R_PPC64_ADDR32: 565 /* Simply set it */ 566 *(u32 *)location = value; 567 break; 568 569 case R_PPC64_ADDR64: 570 /* Simply set it */ 571 *(unsigned long *)location = value; 572 break; 573 574 case R_PPC64_TOC: 575 *(unsigned long *)location = my_r2(sechdrs, me); 576 break; 577 578 case R_PPC64_TOC16: 579 /* Subtract TOC pointer */ 580 value -= my_r2(sechdrs, me); 581 if (value + 0x8000 > 0xffff) { 582 pr_err("%s: bad TOC16 relocation (0x%lx)\n", 583 me->name, value); 584 return -ENOEXEC; 585 } 586 *((uint16_t *) location) 587 = (*((uint16_t *) location) & ~0xffff) 588 | (value & 0xffff); 589 break; 590 591 case R_PPC64_TOC16_LO: 592 /* Subtract TOC pointer */ 593 value -= my_r2(sechdrs, me); 594 *((uint16_t *) location) 595 = (*((uint16_t *) location) & ~0xffff) 596 | (value & 0xffff); 597 break; 598 599 case R_PPC64_TOC16_DS: 600 /* Subtract TOC pointer */ 601 value -= my_r2(sechdrs, me); 602 if ((value & 3) != 0 || value + 0x8000 > 0xffff) { 603 pr_err("%s: bad TOC16_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_LO_DS: 613 /* Subtract TOC pointer */ 614 value -= my_r2(sechdrs, me); 615 if ((value & 3) != 0) { 616 pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n", 617 me->name, value); 618 return -ENOEXEC; 619 } 620 *((uint16_t *) location) 621 = (*((uint16_t *) location) & ~0xfffc) 622 | (value & 0xfffc); 623 break; 624 625 case R_PPC64_TOC16_HA: 626 /* Subtract TOC pointer */ 627 value -= my_r2(sechdrs, me); 628 value = ((value + 0x8000) >> 16); 629 *((uint16_t *) location) 630 = (*((uint16_t *) location) & ~0xffff) 631 | (value & 0xffff); 632 break; 633 634 case R_PPC_REL24: 635 /* FIXME: Handle weak symbols here --RR */ 636 if (sym->st_shndx == SHN_UNDEF || 637 sym->st_shndx == SHN_LIVEPATCH) { 638 /* External: go via stub */ 639 value = stub_for_addr(sechdrs, value, me); 640 if (!value) 641 return -ENOENT; 642 if (!restore_r2(strtab + sym->st_name, 643 (u32 *)location + 1, me)) 644 return -ENOEXEC; 645 646 squash_toc_save_inst(strtab + sym->st_name, value); 647 } else 648 value += local_entry_offset(sym); 649 650 /* Convert value to relative */ 651 value -= (unsigned long)location; 652 if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){ 653 pr_err("%s: REL24 %li out of range!\n", 654 me->name, (long int)value); 655 return -ENOEXEC; 656 } 657 658 /* Only replace bits 2 through 26 */ 659 *(uint32_t *)location 660 = (*(uint32_t *)location & ~0x03fffffc) 661 | (value & 0x03fffffc); 662 break; 663 664 case R_PPC64_REL64: 665 /* 64 bits relative (used by features fixups) */ 666 *location = value - (unsigned long)location; 667 break; 668 669 case R_PPC64_REL32: 670 /* 32 bits relative (used by relative exception tables) */ 671 /* Convert value to relative */ 672 value -= (unsigned long)location; 673 if (value + 0x80000000 > 0xffffffff) { 674 pr_err("%s: REL32 %li out of range!\n", 675 me->name, (long int)value); 676 return -ENOEXEC; 677 } 678 *(u32 *)location = value; 679 break; 680 681 case R_PPC64_TOCSAVE: 682 /* 683 * Marker reloc indicates we don't have to save r2. 684 * That would only save us one instruction, so ignore 685 * it. 686 */ 687 break; 688 689 case R_PPC64_ENTRY: 690 /* 691 * Optimize ELFv2 large code model entry point if 692 * the TOC is within 2GB range of current location. 693 */ 694 value = my_r2(sechdrs, me) - (unsigned long)location; 695 if (value + 0x80008000 > 0xffffffff) 696 break; 697 /* 698 * Check for the large code model prolog sequence: 699 * ld r2, ...(r12) 700 * add r2, r2, r12 701 */ 702 if ((((uint32_t *)location)[0] & ~0xfffc) 703 != 0xe84c0000) 704 break; 705 if (((uint32_t *)location)[1] != 0x7c426214) 706 break; 707 /* 708 * If found, replace it with: 709 * addis r2, r12, (.TOC.-func)@ha 710 * addi r2, r12, (.TOC.-func)@l 711 */ 712 ((uint32_t *)location)[0] = 0x3c4c0000 + PPC_HA(value); 713 ((uint32_t *)location)[1] = 0x38420000 + PPC_LO(value); 714 break; 715 716 case R_PPC64_REL16_HA: 717 /* Subtract location pointer */ 718 value -= (unsigned long)location; 719 value = ((value + 0x8000) >> 16); 720 *((uint16_t *) location) 721 = (*((uint16_t *) location) & ~0xffff) 722 | (value & 0xffff); 723 break; 724 725 case R_PPC64_REL16_LO: 726 /* Subtract location pointer */ 727 value -= (unsigned long)location; 728 *((uint16_t *) location) 729 = (*((uint16_t *) location) & ~0xffff) 730 | (value & 0xffff); 731 break; 732 733 default: 734 pr_err("%s: Unknown ADD relocation: %lu\n", 735 me->name, 736 (unsigned long)ELF64_R_TYPE(rela[i].r_info)); 737 return -ENOEXEC; 738 } 739 } 740 741 return 0; 742 } 743 744 #ifdef CONFIG_DYNAMIC_FTRACE 745 746 #ifdef CONFIG_MPROFILE_KERNEL 747 748 #define PACATOC offsetof(struct paca_struct, kernel_toc) 749 750 /* 751 * For mprofile-kernel we use a special stub for ftrace_caller() because we 752 * can't rely on r2 containing this module's TOC when we enter the stub. 753 * 754 * That can happen if the function calling us didn't need to use the toc. In 755 * that case it won't have setup r2, and the r2 value will be either the 756 * kernel's toc, or possibly another modules toc. 757 * 758 * To deal with that this stub uses the kernel toc, which is always accessible 759 * via the paca (in r13). The target (ftrace_caller()) is responsible for 760 * saving and restoring the toc before returning. 761 */ 762 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, 763 struct module *me, unsigned long addr) 764 { 765 struct ppc64_stub_entry *entry; 766 unsigned int i, num_stubs; 767 static u32 stub_insns[] = { 768 0xe98d0000 | PACATOC, /* ld r12,PACATOC(r13) */ 769 0x3d8c0000, /* addis r12,r12,<high> */ 770 0x398c0000, /* addi r12,r12,<low> */ 771 0x7d8903a6, /* mtctr r12 */ 772 0x4e800420, /* bctr */ 773 }; 774 long reladdr; 775 776 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*entry); 777 778 /* Find the next available stub entry */ 779 entry = (void *)sechdrs[me->arch.stubs_section].sh_addr; 780 for (i = 0; i < num_stubs && stub_func_addr(entry->funcdata); i++, entry++); 781 782 if (i >= num_stubs) { 783 pr_err("%s: Unable to find a free slot for ftrace stub.\n", me->name); 784 return 0; 785 } 786 787 memcpy(entry->jump, stub_insns, sizeof(stub_insns)); 788 789 /* Stub uses address relative to kernel toc (from the paca) */ 790 reladdr = addr - kernel_toc_addr(); 791 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { 792 pr_err("%s: Address of %ps out of range of kernel_toc.\n", 793 me->name, (void *)addr); 794 return 0; 795 } 796 797 entry->jump[1] |= PPC_HA(reladdr); 798 entry->jump[2] |= PPC_LO(reladdr); 799 800 /* Eventhough we don't use funcdata in the stub, it's needed elsewhere. */ 801 entry->funcdata = func_desc(addr); 802 entry->magic = STUB_MAGIC; 803 804 return (unsigned long)entry; 805 } 806 #else 807 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, 808 struct module *me, unsigned long addr) 809 { 810 return stub_for_addr(sechdrs, addr, me); 811 } 812 #endif 813 814 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs) 815 { 816 mod->arch.tramp = create_ftrace_stub(sechdrs, mod, 817 (unsigned long)ftrace_caller); 818 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS 819 mod->arch.tramp_regs = create_ftrace_stub(sechdrs, mod, 820 (unsigned long)ftrace_regs_caller); 821 if (!mod->arch.tramp_regs) 822 return -ENOENT; 823 #endif 824 825 if (!mod->arch.tramp) 826 return -ENOENT; 827 828 return 0; 829 } 830 #endif 831