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 * addis r11,r2, <high> 126 * addi r11,r11, <low> 127 * std r2,R2_STACK_OFFSET(r1) 128 * ld r12,32(r11) 129 * ld r2,40(r11) 130 * mtctr r12 131 * bctr 132 */ 133 static u32 ppc64_stub_insns[] = { 134 PPC_INST_ADDIS | __PPC_RT(R11) | __PPC_RA(R2), 135 PPC_INST_ADDI | __PPC_RT(R11) | __PPC_RA(R11), 136 /* Save current r2 value in magic place on the stack. */ 137 PPC_INST_STD | __PPC_RS(R2) | __PPC_RA(R1) | R2_STACK_OFFSET, 138 PPC_INST_LD | __PPC_RT(R12) | __PPC_RA(R11) | 32, 139 #ifdef PPC64_ELF_ABI_v1 140 /* Set up new r2 from function descriptor */ 141 PPC_INST_LD | __PPC_RT(R2) | __PPC_RA(R11) | 40, 142 #endif 143 PPC_INST_MTCTR | __PPC_RS(R12), 144 PPC_INST_BCTR, 145 }; 146 147 #ifdef CONFIG_DYNAMIC_FTRACE 148 int module_trampoline_target(struct module *mod, unsigned long addr, 149 unsigned long *target) 150 { 151 struct ppc64_stub_entry *stub; 152 func_desc_t funcdata; 153 u32 magic; 154 155 if (!within_module_core(addr, mod)) { 156 pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name); 157 return -EFAULT; 158 } 159 160 stub = (struct ppc64_stub_entry *)addr; 161 162 if (probe_kernel_read(&magic, &stub->magic, sizeof(magic))) { 163 pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name); 164 return -EFAULT; 165 } 166 167 if (magic != STUB_MAGIC) { 168 pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name); 169 return -EFAULT; 170 } 171 172 if (probe_kernel_read(&funcdata, &stub->funcdata, sizeof(funcdata))) { 173 pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name); 174 return -EFAULT; 175 } 176 177 *target = stub_func_addr(funcdata); 178 179 return 0; 180 } 181 #endif 182 183 /* Count how many different 24-bit relocations (different symbol, 184 different addend) */ 185 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num) 186 { 187 unsigned int i, r_info, r_addend, _count_relocs; 188 189 /* FIXME: Only count external ones --RR */ 190 _count_relocs = 0; 191 r_info = 0; 192 r_addend = 0; 193 for (i = 0; i < num; i++) 194 /* Only count 24-bit relocs, others don't need stubs */ 195 if (ELF64_R_TYPE(rela[i].r_info) == R_PPC_REL24 && 196 (r_info != ELF64_R_SYM(rela[i].r_info) || 197 r_addend != rela[i].r_addend)) { 198 _count_relocs++; 199 r_info = ELF64_R_SYM(rela[i].r_info); 200 r_addend = rela[i].r_addend; 201 } 202 203 return _count_relocs; 204 } 205 206 static int relacmp(const void *_x, const void *_y) 207 { 208 const Elf64_Rela *x, *y; 209 210 y = (Elf64_Rela *)_x; 211 x = (Elf64_Rela *)_y; 212 213 /* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to 214 * make the comparison cheaper/faster. It won't affect the sorting or 215 * the counting algorithms' performance 216 */ 217 if (x->r_info < y->r_info) 218 return -1; 219 else if (x->r_info > y->r_info) 220 return 1; 221 else if (x->r_addend < y->r_addend) 222 return -1; 223 else if (x->r_addend > y->r_addend) 224 return 1; 225 else 226 return 0; 227 } 228 229 static void relaswap(void *_x, void *_y, int size) 230 { 231 uint64_t *x, *y, tmp; 232 int i; 233 234 y = (uint64_t *)_x; 235 x = (uint64_t *)_y; 236 237 for (i = 0; i < sizeof(Elf64_Rela) / sizeof(uint64_t); i++) { 238 tmp = x[i]; 239 x[i] = y[i]; 240 y[i] = tmp; 241 } 242 } 243 244 /* Get size of potential trampolines required. */ 245 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr, 246 const Elf64_Shdr *sechdrs) 247 { 248 /* One extra reloc so it's always 0-funcaddr terminated */ 249 unsigned long relocs = 1; 250 unsigned i; 251 252 /* Every relocated section... */ 253 for (i = 1; i < hdr->e_shnum; i++) { 254 if (sechdrs[i].sh_type == SHT_RELA) { 255 pr_debug("Found relocations in section %u\n", i); 256 pr_debug("Ptr: %p. Number: %Lu\n", 257 (void *)sechdrs[i].sh_addr, 258 sechdrs[i].sh_size / sizeof(Elf64_Rela)); 259 260 /* Sort the relocation information based on a symbol and 261 * addend key. This is a stable O(n*log n) complexity 262 * alogrithm but it will reduce the complexity of 263 * count_relocs() to linear complexity O(n) 264 */ 265 sort((void *)sechdrs[i].sh_addr, 266 sechdrs[i].sh_size / sizeof(Elf64_Rela), 267 sizeof(Elf64_Rela), relacmp, relaswap); 268 269 relocs += count_relocs((void *)sechdrs[i].sh_addr, 270 sechdrs[i].sh_size 271 / sizeof(Elf64_Rela)); 272 } 273 } 274 275 #ifdef CONFIG_DYNAMIC_FTRACE 276 /* make the trampoline to the ftrace_caller */ 277 relocs++; 278 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS 279 /* an additional one for ftrace_regs_caller */ 280 relocs++; 281 #endif 282 #endif 283 284 pr_debug("Looks like a total of %lu stubs, max\n", relocs); 285 return relocs * sizeof(struct ppc64_stub_entry); 286 } 287 288 /* Still needed for ELFv2, for .TOC. */ 289 static void dedotify_versions(struct modversion_info *vers, 290 unsigned long size) 291 { 292 struct modversion_info *end; 293 294 for (end = (void *)vers + size; vers < end; vers++) 295 if (vers->name[0] == '.') { 296 memmove(vers->name, vers->name+1, strlen(vers->name)); 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 if (sechdrs[i].sh_addralign < 8) 353 sechdrs[i].sh_addralign = 8; 354 } 355 else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0) 356 dedotify_versions((void *)hdr + sechdrs[i].sh_offset, 357 sechdrs[i].sh_size); 358 359 /* We don't handle .init for the moment: rename to _init */ 360 while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init"))) 361 p[0] = '_'; 362 363 if (sechdrs[i].sh_type == SHT_SYMTAB) 364 dedotify((void *)hdr + sechdrs[i].sh_offset, 365 sechdrs[i].sh_size / sizeof(Elf64_Sym), 366 (void *)hdr 367 + sechdrs[sechdrs[i].sh_link].sh_offset); 368 } 369 370 if (!me->arch.stubs_section) { 371 pr_err("%s: doesn't contain .stubs.\n", me->name); 372 return -ENOEXEC; 373 } 374 375 /* If we don't have a .toc, just use .stubs. We need to set r2 376 to some reasonable value in case the module calls out to 377 other functions via a stub, or if a function pointer escapes 378 the module by some means. */ 379 if (!me->arch.toc_section) 380 me->arch.toc_section = me->arch.stubs_section; 381 382 /* Override the stubs size */ 383 sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs); 384 return 0; 385 } 386 387 /* 388 * r2 is the TOC pointer: it actually points 0x8000 into the TOC (this gives the 389 * value maximum span in an instruction which uses a signed offset). Round down 390 * to a 256 byte boundary for the odd case where we are setting up r2 without a 391 * .toc section. 392 */ 393 static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me) 394 { 395 return (sechdrs[me->arch.toc_section].sh_addr & ~0xfful) + 0x8000; 396 } 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 (PPC_INST_LD | __PPC_RT(R2) | __PPC_RA(R12))) 704 break; 705 if (((uint32_t *)location)[1] != 706 (PPC_INST_ADD | __PPC_RT(R2) | __PPC_RA(R2) | __PPC_RB(R12))) 707 break; 708 /* 709 * If found, replace it with: 710 * addis r2, r12, (.TOC.-func)@ha 711 * addi r2, r2, (.TOC.-func)@l 712 */ 713 ((uint32_t *)location)[0] = PPC_INST_ADDIS | __PPC_RT(R2) | 714 __PPC_RA(R12) | PPC_HA(value); 715 ((uint32_t *)location)[1] = PPC_INST_ADDI | __PPC_RT(R2) | 716 __PPC_RA(R2) | PPC_LO(value); 717 break; 718 719 case R_PPC64_REL16_HA: 720 /* Subtract location pointer */ 721 value -= (unsigned long)location; 722 value = ((value + 0x8000) >> 16); 723 *((uint16_t *) location) 724 = (*((uint16_t *) location) & ~0xffff) 725 | (value & 0xffff); 726 break; 727 728 case R_PPC64_REL16_LO: 729 /* Subtract location pointer */ 730 value -= (unsigned long)location; 731 *((uint16_t *) location) 732 = (*((uint16_t *) location) & ~0xffff) 733 | (value & 0xffff); 734 break; 735 736 default: 737 pr_err("%s: Unknown ADD relocation: %lu\n", 738 me->name, 739 (unsigned long)ELF64_R_TYPE(rela[i].r_info)); 740 return -ENOEXEC; 741 } 742 } 743 744 return 0; 745 } 746 747 #ifdef CONFIG_DYNAMIC_FTRACE 748 749 #ifdef CONFIG_MPROFILE_KERNEL 750 751 #define PACATOC offsetof(struct paca_struct, kernel_toc) 752 753 /* 754 * For mprofile-kernel we use a special stub for ftrace_caller() because we 755 * can't rely on r2 containing this module's TOC when we enter the stub. 756 * 757 * That can happen if the function calling us didn't need to use the toc. In 758 * that case it won't have setup r2, and the r2 value will be either the 759 * kernel's toc, or possibly another modules toc. 760 * 761 * To deal with that this stub uses the kernel toc, which is always accessible 762 * via the paca (in r13). The target (ftrace_caller()) is responsible for 763 * saving and restoring the toc before returning. 764 */ 765 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, 766 struct module *me, unsigned long addr) 767 { 768 struct ppc64_stub_entry *entry; 769 unsigned int i, num_stubs; 770 /* 771 * ld r12,PACATOC(r13) 772 * addis r12,r12,<high> 773 * addi r12,r12,<low> 774 * mtctr r12 775 * bctr 776 */ 777 static u32 stub_insns[] = { 778 PPC_INST_LD | __PPC_RT(R12) | __PPC_RA(R13) | PACATOC, 779 PPC_INST_ADDIS | __PPC_RT(R12) | __PPC_RA(R12), 780 PPC_INST_ADDI | __PPC_RT(R12) | __PPC_RA(R12), 781 PPC_INST_MTCTR | __PPC_RS(R12), 782 PPC_INST_BCTR, 783 }; 784 long reladdr; 785 786 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*entry); 787 788 /* Find the next available stub entry */ 789 entry = (void *)sechdrs[me->arch.stubs_section].sh_addr; 790 for (i = 0; i < num_stubs && stub_func_addr(entry->funcdata); i++, entry++); 791 792 if (i >= num_stubs) { 793 pr_err("%s: Unable to find a free slot for ftrace stub.\n", me->name); 794 return 0; 795 } 796 797 memcpy(entry->jump, stub_insns, sizeof(stub_insns)); 798 799 /* Stub uses address relative to kernel toc (from the paca) */ 800 reladdr = addr - kernel_toc_addr(); 801 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { 802 pr_err("%s: Address of %ps out of range of kernel_toc.\n", 803 me->name, (void *)addr); 804 return 0; 805 } 806 807 entry->jump[1] |= PPC_HA(reladdr); 808 entry->jump[2] |= PPC_LO(reladdr); 809 810 /* Eventhough we don't use funcdata in the stub, it's needed elsewhere. */ 811 entry->funcdata = func_desc(addr); 812 entry->magic = STUB_MAGIC; 813 814 return (unsigned long)entry; 815 } 816 #else 817 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, 818 struct module *me, unsigned long addr) 819 { 820 return stub_for_addr(sechdrs, addr, me); 821 } 822 #endif 823 824 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs) 825 { 826 mod->arch.tramp = create_ftrace_stub(sechdrs, mod, 827 (unsigned long)ftrace_caller); 828 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS 829 mod->arch.tramp_regs = create_ftrace_stub(sechdrs, mod, 830 (unsigned long)ftrace_regs_caller); 831 if (!mod->arch.tramp_regs) 832 return -ENOENT; 833 #endif 834 835 if (!mod->arch.tramp) 836 return -ENOENT; 837 838 return 0; 839 } 840 #endif 841