arch/powerpc/kernel/module_64.c

   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 <linux/kernel.h>
  18 #include <asm/module.h>
  19 #include <asm/firmware.h>
  20 #include <asm/text-patching.h>
  21 #include <linux/sort.h>
  22 #include <asm/setup.h>
  23 #include <asm/sections.h>
  24 #include <asm/inst.h>
  25
  26 /* FIXME: We don't do .init separately.  To do this, we'd need to have
  27    a separate r2 value in the init and core section, and stub between
  28    them, too.
  29
  30    Using a magic allocator which places modules within 32MB solves
  31    this, and makes other things simpler.  Anton?
  32    --RR.  */
  33
  34 bool module_elf_check_arch(Elf_Ehdr *hdr)
  35 {
  36         unsigned long abi_level = hdr->e_flags & 0x3;
  37
  38         if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2))
  39                 return abi_level == 2;
  40         else
  41                 return abi_level < 2;
  42 }
  43
  44 #ifdef CONFIG_PPC64_ELF_ABI_V2
  45
  46 static func_desc_t func_desc(unsigned long addr)
  47 {
  48         func_desc_t desc = {
  49                 .addr = addr,
  50         };
  51
  52         return desc;
  53 }
  54
  55 /* PowerPC64 specific values for the Elf64_Sym st_other field.  */
  56 #define STO_PPC64_LOCAL_BIT     5
  57 #define STO_PPC64_LOCAL_MASK    (7 << STO_PPC64_LOCAL_BIT)
  58 #define PPC64_LOCAL_ENTRY_OFFSET(other)                                 \
  59  (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
  60
  61 static unsigned int local_entry_offset(const Elf64_Sym *sym)
  62 {
  63         /* sym->st_other indicates offset to local entry point
  64          * (otherwise it will assume r12 is the address of the start
  65          * of function and try to derive r2 from it). */
  66         return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
  67 }
  68 #else
  69
  70 static func_desc_t func_desc(unsigned long addr)
  71 {
  72         return *(struct func_desc *)addr;
  73 }
  74 static unsigned int local_entry_offset(const Elf64_Sym *sym)
  75 {
  76         return 0;
  77 }
  78
  79 void *dereference_module_function_descriptor(struct module *mod, void *ptr)
  80 {
  81         if (ptr < (void *)mod->arch.start_opd ||
  82                         ptr >= (void *)mod->arch.end_opd)
  83                 return ptr;
  84
  85         return dereference_function_descriptor(ptr);
  86 }
  87 #endif
  88
  89 static unsigned long func_addr(unsigned long addr)
  90 {
  91         return func_desc(addr).addr;
  92 }
  93
  94 static unsigned long stub_func_addr(func_desc_t func)
  95 {
  96         return func.addr;
  97 }
  98
  99 #define STUB_MAGIC 0x73747562 /* stub */
 100
 101 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into
 102    the kernel itself).  But on PPC64, these need to be used for every
 103    jump, actually, to reset r2 (TOC+0x8000). */
 104 struct ppc64_stub_entry {
 105         /*
 106          * 28 byte jump instruction sequence (7 instructions) that can
 107          * hold ppc64_stub_insns or stub_insns. Must be 8-byte aligned
 108          * with PCREL kernels that use prefix instructions in the stub.
 109          */
 110         u32 jump[7];
 111         /* Used by ftrace to identify stubs */
 112         u32 magic;
 113         /* Data for the above code */
 114         func_desc_t funcdata;
 115 } __aligned(8);
 116
 117 struct ppc64_got_entry {
 118         u64 addr;
 119 };
 120
 121 /*
 122  * PPC64 uses 24 bit jumps, but we need to jump into other modules or
 123  * the kernel which may be further.  So we jump to a stub.
 124  *
 125  * Target address and TOC are loaded from function descriptor in the
 126  * ppc64_stub_entry.
 127  *
 128  * r12 is used to generate the target address, which is required for the
 129  * ELFv2 global entry point calling convention.
 130  *
 131  * TOC handling:
 132  * - PCREL does not have a TOC.
 133  * - ELFv2 non-PCREL just has to save r2, the callee is responsible for
 134  *   setting its own TOC pointer at the global entry address.
 135  * - ELFv1 must load the new TOC pointer from the function descriptor.
 136  */
 137 static u32 ppc64_stub_insns[] = {
 138 #ifdef CONFIG_PPC_KERNEL_PCREL
 139         /* pld r12,addr */
 140         PPC_PREFIX_8LS | __PPC_PRFX_R(1),
 141         PPC_INST_PLD | ___PPC_RT(_R12),
 142 #else
 143         PPC_RAW_ADDIS(_R11, _R2, 0),
 144         PPC_RAW_ADDI(_R11, _R11, 0),
 145         /* Save current r2 value in magic place on the stack. */
 146         PPC_RAW_STD(_R2, _R1, R2_STACK_OFFSET),
 147         PPC_RAW_LD(_R12, _R11, 32),
 148 #ifdef CONFIG_PPC64_ELF_ABI_V1
 149         /* Set up new r2 from function descriptor */
 150         PPC_RAW_LD(_R2, _R11, 40),
 151 #endif
 152 #endif
 153         PPC_RAW_MTCTR(_R12),
 154         PPC_RAW_BCTR(),
 155 };
 156
 157 /*
 158  * Count how many different r_type relocations (different symbol,
 159  * different addend).
 160  */
 161 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num,
 162                                  unsigned long r_type)
 163 {
 164         unsigned int i, r_info, r_addend, _count_relocs;
 165
 166         /* FIXME: Only count external ones --RR */
 167         _count_relocs = 0;
 168         r_info = 0;
 169         r_addend = 0;
 170         for (i = 0; i < num; i++)
 171                 /* Only count r_type relocs, others don't need stubs */
 172                 if (ELF64_R_TYPE(rela[i].r_info) == r_type &&
 173                     (r_info != ELF64_R_SYM(rela[i].r_info) ||
 174                      r_addend != rela[i].r_addend)) {
 175                         _count_relocs++;
 176                         r_info = ELF64_R_SYM(rela[i].r_info);
 177                         r_addend = rela[i].r_addend;
 178                 }
 179
 180         return _count_relocs;
 181 }
 182
 183 static int relacmp(const void *_x, const void *_y)
 184 {
 185         const Elf64_Rela *x, *y;
 186
 187         y = (Elf64_Rela *)_x;
 188         x = (Elf64_Rela *)_y;
 189
 190         /* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to
 191          * make the comparison cheaper/faster. It won't affect the sorting or
 192          * the counting algorithms' performance
 193          */
 194         if (x->r_info < y->r_info)
 195                 return -1;
 196         else if (x->r_info > y->r_info)
 197                 return 1;
 198         else if (x->r_addend < y->r_addend)
 199                 return -1;
 200         else if (x->r_addend > y->r_addend)
 201                 return 1;
 202         else
 203                 return 0;
 204 }
 205
 206 /* Get size of potential trampolines required. */
 207 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
 208                                     const Elf64_Shdr *sechdrs,
 209                                     char *secstrings,
 210                                     struct module *me)
 211 {
 212         /* One extra reloc so it's always 0-addr terminated */
 213         unsigned long relocs = 1;
 214         unsigned i;
 215
 216         /* Every relocated section... */
 217         for (i = 1; i < hdr->e_shnum; i++) {
 218                 if (sechdrs[i].sh_type == SHT_RELA) {
 219                         pr_debug("Found relocations in section %u\n", i);
 220                         pr_debug("Ptr: %p.  Number: %Lu\n",
 221                                (void *)sechdrs[i].sh_addr,
 222                                sechdrs[i].sh_size / sizeof(Elf64_Rela));
 223
 224                         /* Sort the relocation information based on a symbol and
 225                          * addend key. This is a stable O(n*log n) complexity
 226                          * algorithm but it will reduce the complexity of
 227                          * count_relocs() to linear complexity O(n)
 228                          */
 229                         sort((void *)sechdrs[i].sh_addr,
 230                              sechdrs[i].sh_size / sizeof(Elf64_Rela),
 231                              sizeof(Elf64_Rela), relacmp, NULL);
 232
 233                         relocs += count_relocs((void *)sechdrs[i].sh_addr,
 234                                                sechdrs[i].sh_size
 235                                                / sizeof(Elf64_Rela),
 236                                                R_PPC_REL24);
 237 #ifdef CONFIG_PPC_KERNEL_PCREL
 238                         relocs += count_relocs((void *)sechdrs[i].sh_addr,
 239                                                sechdrs[i].sh_size
 240                                                / sizeof(Elf64_Rela),
 241                                                R_PPC64_REL24_NOTOC);
 242 #endif
 243                 }
 244         }
 245
 246         /* stubs for ftrace_caller and ftrace_regs_caller */
 247         relocs += IS_ENABLED(CONFIG_DYNAMIC_FTRACE) + IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS);
 248
 249 #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
 250         /* stubs for the function tracer */
 251         for (i = 1; i < hdr->e_shnum; i++) {
 252                 if (!strcmp(secstrings + sechdrs[i].sh_name, "__patchable_function_entries")) {
 253                         me->arch.ool_stub_count = sechdrs[i].sh_size / sizeof(unsigned long);
 254                         me->arch.ool_stub_index = 0;
 255                         relocs += roundup(me->arch.ool_stub_count * sizeof(struct ftrace_ool_stub),
 256                                           sizeof(struct ppc64_stub_entry)) /
 257                                   sizeof(struct ppc64_stub_entry);
 258                         break;
 259                 }
 260         }
 261         if (i == hdr->e_shnum) {
 262                 pr_err("%s: doesn't contain __patchable_function_entries.\n", me->name);
 263                 return -ENOEXEC;
 264         }
 265 #endif
 266
 267         pr_debug("Looks like a total of %lu stubs, max\n", relocs);
 268         return relocs * sizeof(struct ppc64_stub_entry);
 269 }
 270
 271 #ifdef CONFIG_PPC_KERNEL_PCREL
 272 static int count_pcpu_relocs(const Elf64_Shdr *sechdrs,
 273                              const Elf64_Rela *rela, unsigned int num,
 274                              unsigned int symindex, unsigned int pcpu)
 275 {
 276         unsigned int i, r_info, r_addend, _count_relocs;
 277
 278         _count_relocs = 0;
 279         r_info = 0;
 280         r_addend = 0;
 281
 282         for (i = 0; i < num; i++) {
 283                 Elf64_Sym *sym;
 284
 285                 /* This is the symbol it is referring to */
 286                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
 287                         + ELF64_R_SYM(rela[i].r_info);
 288
 289                 if (sym->st_shndx == pcpu &&
 290                     (r_info != ELF64_R_SYM(rela[i].r_info) ||
 291                      r_addend != rela[i].r_addend)) {
 292                         _count_relocs++;
 293                         r_info = ELF64_R_SYM(rela[i].r_info);
 294                         r_addend = rela[i].r_addend;
 295                 }
 296         }
 297
 298         return _count_relocs;
 299 }
 300
 301 /* Get size of potential GOT required. */
 302 static unsigned long get_got_size(const Elf64_Ehdr *hdr,
 303                                   const Elf64_Shdr *sechdrs,
 304                                   struct module *me)
 305 {
 306         /* One extra reloc so it's always 0-addr terminated */
 307         unsigned long relocs = 1;
 308         unsigned int i, symindex = 0;
 309
 310         for (i = 1; i < hdr->e_shnum; i++) {
 311                 if (sechdrs[i].sh_type == SHT_SYMTAB) {
 312                         symindex = i;
 313                         break;
 314                 }
 315         }
 316         WARN_ON_ONCE(!symindex);
 317
 318         /* Every relocated section... */
 319         for (i = 1; i < hdr->e_shnum; i++) {
 320                 if (sechdrs[i].sh_type == SHT_RELA) {
 321                         pr_debug("Found relocations in section %u\n", i);
 322                         pr_debug("Ptr: %p.  Number: %llu\n", (void *)sechdrs[i].sh_addr,
 323                                  sechdrs[i].sh_size / sizeof(Elf64_Rela));
 324
 325                         /*
 326                          * Sort the relocation information based on a symbol and
 327                          * addend key. This is a stable O(n*log n) complexity
 328                          * algorithm but it will reduce the complexity of
 329                          * count_relocs() to linear complexity O(n)
 330                          */
 331                         sort((void *)sechdrs[i].sh_addr,
 332                              sechdrs[i].sh_size / sizeof(Elf64_Rela),
 333                              sizeof(Elf64_Rela), relacmp, NULL);
 334
 335                         relocs += count_relocs((void *)sechdrs[i].sh_addr,
 336                                                sechdrs[i].sh_size
 337                                                / sizeof(Elf64_Rela),
 338                                                R_PPC64_GOT_PCREL34);
 339
 340                         /*
 341                          * Percpu data access typically gets linked with
 342                          * REL34 relocations, but the percpu section gets
 343                          * moved at load time and requires that to be
 344                          * converted to GOT linkage.
 345                          */
 346                         if (IS_ENABLED(CONFIG_SMP) && symindex)
 347                                 relocs += count_pcpu_relocs(sechdrs,
 348                                                 (void *)sechdrs[i].sh_addr,
 349                                                sechdrs[i].sh_size
 350                                                / sizeof(Elf64_Rela),
 351                                                symindex, me->arch.pcpu_section);
 352                 }
 353         }
 354
 355         pr_debug("Looks like a total of %lu GOT entries, max\n", relocs);
 356         return relocs * sizeof(struct ppc64_got_entry);
 357 }
 358 #else /* CONFIG_PPC_KERNEL_PCREL */
 359
 360 /* Still needed for ELFv2, for .TOC. */
 361 static void dedotify_versions(struct modversion_info *vers,
 362                               unsigned long size)
 363 {
 364         struct modversion_info *end;
 365
 366         for (end = (void *)vers + size; vers < end; vers++)
 367                 if (vers->name[0] == '.') {
 368                         memmove(vers->name, vers->name+1, strlen(vers->name));
 369                 }
 370 }
 371
 372 /*
 373  * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
 374  * seem to be defined (value set later).
 375  */
 376 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
 377 {
 378         unsigned int i;
 379
 380         for (i = 1; i < numsyms; i++) {
 381                 if (syms[i].st_shndx == SHN_UNDEF) {
 382                         char *name = strtab + syms[i].st_name;
 383                         if (name[0] == '.') {
 384                                 if (strcmp(name+1, "TOC.") == 0)
 385                                         syms[i].st_shndx = SHN_ABS;
 386                                 syms[i].st_name++;
 387                         }
 388                 }
 389         }
 390 }
 391
 392 static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
 393                                const char *strtab,
 394                                unsigned int symindex)
 395 {
 396         unsigned int i, numsyms;
 397         Elf64_Sym *syms;
 398
 399         syms = (Elf64_Sym *)sechdrs[symindex].sh_addr;
 400         numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
 401
 402         for (i = 1; i < numsyms; i++) {
 403                 if (syms[i].st_shndx == SHN_ABS
 404                     && strcmp(strtab + syms[i].st_name, "TOC.") == 0)
 405                         return &syms[i];
 406         }
 407         return NULL;
 408 }
 409 #endif /* CONFIG_PPC_KERNEL_PCREL */
 410
 411 bool module_init_section(const char *name)
 412 {
 413         /* We don't handle .init for the moment: always return false. */
 414         return false;
 415 }
 416
 417 int module_frob_arch_sections(Elf64_Ehdr *hdr,
 418                               Elf64_Shdr *sechdrs,
 419                               char *secstrings,
 420                               struct module *me)
 421 {
 422         unsigned int i;
 423
 424         /* Find .toc and .stubs sections, symtab and strtab */
 425         for (i = 1; i < hdr->e_shnum; i++) {
 426                 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
 427                         me->arch.stubs_section = i;
 428 #ifdef CONFIG_PPC_KERNEL_PCREL
 429                 else if (strcmp(secstrings + sechdrs[i].sh_name, ".data..percpu") == 0)
 430                         me->arch.pcpu_section = i;
 431                 else if (strcmp(secstrings + sechdrs[i].sh_name, ".mygot") == 0) {
 432                         me->arch.got_section = i;
 433                         if (sechdrs[i].sh_addralign < 8)
 434                                 sechdrs[i].sh_addralign = 8;
 435                 }
 436 #else
 437                 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) {
 438                         me->arch.toc_section = i;
 439                         if (sechdrs[i].sh_addralign < 8)
 440                                 sechdrs[i].sh_addralign = 8;
 441                 }
 442                 else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
 443                         dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
 444                                           sechdrs[i].sh_size);
 445
 446                 if (sechdrs[i].sh_type == SHT_SYMTAB)
 447                         dedotify((void *)hdr + sechdrs[i].sh_offset,
 448                                  sechdrs[i].sh_size / sizeof(Elf64_Sym),
 449                                  (void *)hdr
 450                                  + sechdrs[sechdrs[i].sh_link].sh_offset);
 451 #endif
 452         }
 453
 454         if (!me->arch.stubs_section) {
 455                 pr_err("%s: doesn't contain .stubs.\n", me->name);
 456                 return -ENOEXEC;
 457         }
 458
 459 #ifdef CONFIG_PPC_KERNEL_PCREL
 460         if (!me->arch.got_section) {
 461                 pr_err("%s: doesn't contain .mygot.\n", me->name);
 462                 return -ENOEXEC;
 463         }
 464
 465         /* Override the got size */
 466         sechdrs[me->arch.got_section].sh_size = get_got_size(hdr, sechdrs, me);
 467 #else
 468         /* If we don't have a .toc, just use .stubs.  We need to set r2
 469            to some reasonable value in case the module calls out to
 470            other functions via a stub, or if a function pointer escapes
 471            the module by some means.  */
 472         if (!me->arch.toc_section)
 473                 me->arch.toc_section = me->arch.stubs_section;
 474 #endif
 475
 476         /* Override the stubs size */
 477         sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs, secstrings, me);
 478
 479         return 0;
 480 }
 481
 482 #if defined(CONFIG_MPROFILE_KERNEL) || defined(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)
 483
 484 static u32 stub_insns[] = {
 485 #ifdef CONFIG_PPC_KERNEL_PCREL
 486         PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernelbase)),
 487         PPC_RAW_NOP(), /* align the prefix insn */
 488         /* paddi r12,r12,addr */
 489         PPC_PREFIX_MLS | __PPC_PRFX_R(0),
 490         PPC_INST_PADDI | ___PPC_RT(_R12) | ___PPC_RA(_R12),
 491         PPC_RAW_MTCTR(_R12),
 492         PPC_RAW_BCTR(),
 493 #else
 494         PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
 495         PPC_RAW_ADDIS(_R12, _R12, 0),
 496         PPC_RAW_ADDI(_R12, _R12, 0),
 497         PPC_RAW_MTCTR(_R12),
 498         PPC_RAW_BCTR(),
 499 #endif
 500 };
 501
 502 /*
 503  * For mprofile-kernel we use a special stub for ftrace_caller() because we
 504  * can't rely on r2 containing this module's TOC when we enter the stub.
 505  *
 506  * That can happen if the function calling us didn't need to use the toc. In
 507  * that case it won't have setup r2, and the r2 value will be either the
 508  * kernel's toc, or possibly another modules toc.
 509  *
 510  * To deal with that this stub uses the kernel toc, which is always accessible
 511  * via the paca (in r13). The target (ftrace_caller()) is responsible for
 512  * saving and restoring the toc before returning.
 513  */
 514 static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
 515                                         unsigned long addr,
 516                                         struct module *me)
 517 {
 518         long reladdr;
 519
 520         if ((unsigned long)entry->jump % 8 != 0) {
 521                 pr_err("%s: Address of stub entry is not 8-byte aligned\n", me->name);
 522                 return 0;
 523         }
 524
 525         BUILD_BUG_ON(sizeof(stub_insns) > sizeof(entry->jump));
 526         memcpy(entry->jump, stub_insns, sizeof(stub_insns));
 527
 528         if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
 529                 /* Stub uses address relative to kernel base (from the paca) */
 530                 reladdr = addr - local_paca->kernelbase;
 531                 if (reladdr > 0x1FFFFFFFFL || reladdr < -0x200000000L) {
 532                         pr_err("%s: Address of %ps out of range of 34-bit relative address.\n",
 533                                 me->name, (void *)addr);
 534                         return 0;
 535                 }
 536
 537                 entry->jump[2] |= IMM_H18(reladdr);
 538                 entry->jump[3] |= IMM_L(reladdr);
 539         } else {
 540                 /* Stub uses address relative to kernel toc (from the paca) */
 541                 reladdr = addr - kernel_toc_addr();
 542                 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
 543                         pr_err("%s: Address of %ps out of range of kernel_toc.\n",
 544                                 me->name, (void *)addr);
 545                         return 0;
 546                 }
 547
 548                 entry->jump[1] |= PPC_HA(reladdr);
 549                 entry->jump[2] |= PPC_LO(reladdr);
 550         }
 551
 552         /* Even though we don't use funcdata in the stub, it's needed elsewhere. */
 553         entry->funcdata = func_desc(addr);
 554         entry->magic = STUB_MAGIC;
 555
 556         return 1;
 557 }
 558
 559 static bool is_mprofile_ftrace_call(const char *name)
 560 {
 561         if (!strcmp("_mcount", name))
 562                 return true;
 563 #ifdef CONFIG_DYNAMIC_FTRACE
 564         if (!strcmp("ftrace_caller", name))
 565                 return true;
 566 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 567         if (!strcmp("ftrace_regs_caller", name))
 568                 return true;
 569 #endif
 570 #endif
 571
 572         return false;
 573 }
 574 #else
 575 static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
 576                                         unsigned long addr,
 577                                         struct module *me)
 578 {
 579         return 0;
 580 }
 581
 582 static bool is_mprofile_ftrace_call(const char *name)
 583 {
 584         return false;
 585 }
 586 #endif
 587
 588 /*
 589  * r2 is the TOC pointer: it actually points 0x8000 into the TOC (this gives the
 590  * value maximum span in an instruction which uses a signed offset). Round down
 591  * to a 256 byte boundary for the odd case where we are setting up r2 without a
 592  * .toc section.
 593  */
 594 static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me)
 595 {
 596 #ifndef CONFIG_PPC_KERNEL_PCREL
 597         return (sechdrs[me->arch.toc_section].sh_addr & ~0xfful) + 0x8000;
 598 #else
 599         return -1;
 600 #endif
 601 }
 602
 603 /* Patch stub to reference function and correct r2 value. */
 604 static inline int create_stub(const Elf64_Shdr *sechdrs,
 605                               struct ppc64_stub_entry *entry,
 606                               unsigned long addr,
 607                               struct module *me,
 608                               const char *name)
 609 {
 610         long reladdr;
 611         func_desc_t desc;
 612         int i;
 613
 614         if (is_mprofile_ftrace_call(name))
 615                 return create_ftrace_stub(entry, addr, me);
 616
 617         if ((unsigned long)entry->jump % 8 != 0) {
 618                 pr_err("%s: Address of stub entry is not 8-byte aligned\n", me->name);
 619                 return 0;
 620         }
 621
 622         BUILD_BUG_ON(sizeof(ppc64_stub_insns) > sizeof(entry->jump));
 623         for (i = 0; i < ARRAY_SIZE(ppc64_stub_insns); i++) {
 624                 if (patch_instruction(&entry->jump[i],
 625                                       ppc_inst(ppc64_stub_insns[i])))
 626                         return 0;
 627         }
 628
 629         if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
 630                 /* Stub uses address relative to itself! */
 631                 reladdr = 0 + offsetof(struct ppc64_stub_entry, funcdata);
 632                 BUILD_BUG_ON(reladdr != 32);
 633                 if (reladdr > 0x1FFFFFFFFL || reladdr < -0x200000000L) {
 634                         pr_err("%s: Address of %p out of range of 34-bit relative address.\n",
 635                                 me->name, (void *)reladdr);
 636                         return 0;
 637                 }
 638                 pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
 639
 640                 /* May not even need this if we're relative to 0 */
 641                 if (patch_instruction(&entry->jump[0],
 642                     ppc_inst_prefix(entry->jump[0] | IMM_H18(reladdr),
 643                                     entry->jump[1] | IMM_L(reladdr))))
 644                         return 0;
 645
 646         } else {
 647                 /* Stub uses address relative to r2. */
 648                 reladdr = (unsigned long)entry - my_r2(sechdrs, me);
 649                 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
 650                         pr_err("%s: Address %p of stub out of range of %p.\n",
 651                                me->name, (void *)reladdr, (void *)my_r2);
 652                         return 0;
 653                 }
 654                 pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
 655
 656                 if (patch_instruction(&entry->jump[0],
 657                                       ppc_inst(entry->jump[0] | PPC_HA(reladdr))))
 658                         return 0;
 659
 660                 if (patch_instruction(&entry->jump[1],
 661                                       ppc_inst(entry->jump[1] | PPC_LO(reladdr))))
 662                         return 0;
 663         }
 664
 665         // func_desc_t is 8 bytes if ABIv2, else 16 bytes
 666         desc = func_desc(addr);
 667         for (i = 0; i < sizeof(func_desc_t) / sizeof(u32); i++) {
 668                 if (patch_u32(((u32 *)&entry->funcdata) + i, ((u32 *)&desc)[i]))
 669                         return 0;
 670         }
 671
 672         if (patch_u32(&entry->magic, STUB_MAGIC))
 673                 return 0;
 674
 675         return 1;
 676 }
 677
 678 /* Create stub to jump to function described in this OPD/ptr: we need the
 679    stub to set up the TOC ptr (r2) for the function. */
 680 static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
 681                                    unsigned long addr,
 682                                    struct module *me,
 683                                    const char *name)
 684 {
 685         struct ppc64_stub_entry *stubs;
 686         unsigned int i, num_stubs;
 687
 688         num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
 689
 690         /* Find this stub, or if that fails, the next avail. entry */
 691         stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
 692         for (i = 0; stub_func_addr(stubs[i].funcdata); i++) {
 693                 if (WARN_ON(i >= num_stubs))
 694                         return 0;
 695
 696                 if (stub_func_addr(stubs[i].funcdata) == func_addr(addr))
 697                         return (unsigned long)&stubs[i];
 698         }
 699
 700         if (!create_stub(sechdrs, &stubs[i], addr, me, name))
 701                 return 0;
 702
 703         return (unsigned long)&stubs[i];
 704 }
 705
 706 #ifdef CONFIG_PPC_KERNEL_PCREL
 707 /* Create GOT to load the location described in this ptr */
 708 static unsigned long got_for_addr(const Elf64_Shdr *sechdrs,
 709                                   unsigned long addr,
 710                                   struct module *me,
 711                                   const char *name)
 712 {
 713         struct ppc64_got_entry *got;
 714         unsigned int i, num_got;
 715
 716         if (!IS_ENABLED(CONFIG_PPC_KERNEL_PCREL))
 717                 return addr;
 718
 719         num_got = sechdrs[me->arch.got_section].sh_size / sizeof(*got);
 720
 721         /* Find this stub, or if that fails, the next avail. entry */
 722         got = (void *)sechdrs[me->arch.got_section].sh_addr;
 723         for (i = 0; got[i].addr; i++) {
 724                 if (WARN_ON(i >= num_got))
 725                         return 0;
 726
 727                 if (got[i].addr == addr)
 728                         return (unsigned long)&got[i];
 729         }
 730
 731         got[i].addr = addr;
 732
 733         return (unsigned long)&got[i];
 734 }
 735 #endif
 736
 737 /* We expect a noop next: if it is, replace it with instruction to
 738    restore r2. */
 739 static int restore_r2(const char *name, u32 *instruction, struct module *me)
 740 {
 741         u32 *prev_insn = instruction - 1;
 742         u32 insn_val = *instruction;
 743
 744         if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL))
 745                 return 0;
 746
 747         if (is_mprofile_ftrace_call(name))
 748                 return 0;
 749
 750         /*
 751          * Make sure the branch isn't a sibling call.  Sibling calls aren't
 752          * "link" branches and they don't return, so they don't need the r2
 753          * restore afterwards.
 754          */
 755         if (!instr_is_relative_link_branch(ppc_inst(*prev_insn)))
 756                 return 0;
 757
 758         /*
 759          * For livepatch, the restore r2 instruction might have already been
 760          * written previously, if the referenced symbol is in a previously
 761          * unloaded module which is now being loaded again.  In that case, skip
 762          * the warning and the instruction write.
 763          */
 764         if (insn_val == PPC_INST_LD_TOC)
 765                 return 0;
 766
 767         if (insn_val != PPC_RAW_NOP()) {
 768                 pr_err("%s: Expected nop after call, got %08x at %pS\n",
 769                         me->name, insn_val, instruction);
 770                 return -ENOEXEC;
 771         }
 772
 773         /* ld r2,R2_STACK_OFFSET(r1) */
 774         return patch_instruction(instruction, ppc_inst(PPC_INST_LD_TOC));
 775 }
 776
 777 int apply_relocate_add(Elf64_Shdr *sechdrs,
 778                        const char *strtab,
 779                        unsigned int symindex,
 780                        unsigned int relsec,
 781                        struct module *me)
 782 {
 783         unsigned int i;
 784         Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
 785         Elf64_Sym *sym;
 786         unsigned long *location;
 787         unsigned long value;
 788
 789         pr_debug("Applying ADD relocate section %u to %u\n", relsec,
 790                sechdrs[relsec].sh_info);
 791
 792 #ifndef CONFIG_PPC_KERNEL_PCREL
 793         /* First time we're called, we can fix up .TOC. */
 794         if (!me->arch.toc_fixed) {
 795                 sym = find_dot_toc(sechdrs, strtab, symindex);
 796                 /* It's theoretically possible that a module doesn't want a
 797                  * .TOC. so don't fail it just for that. */
 798                 if (sym)
 799                         sym->st_value = my_r2(sechdrs, me);
 800                 me->arch.toc_fixed = true;
 801         }
 802 #endif
 803         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
 804                 /* This is where to make the change */
 805                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 806                         + rela[i].r_offset;
 807                 /* This is the symbol it is referring to */
 808                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
 809                         + ELF64_R_SYM(rela[i].r_info);
 810
 811                 pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
 812                        location, (long)ELF64_R_TYPE(rela[i].r_info),
 813                        strtab + sym->st_name, (unsigned long)sym->st_value,
 814                        (long)rela[i].r_addend);
 815
 816                 /* `Everything is relative'. */
 817                 value = sym->st_value + rela[i].r_addend;
 818
 819                 switch (ELF64_R_TYPE(rela[i].r_info)) {
 820                 case R_PPC64_ADDR32:
 821                         /* Simply set it */
 822                         *(u32 *)location = value;
 823                         break;
 824
 825                 case R_PPC64_ADDR64:
 826                         /* Simply set it */
 827                         *(unsigned long *)location = value;
 828                         break;
 829
 830 #ifndef CONFIG_PPC_KERNEL_PCREL
 831                 case R_PPC64_TOC:
 832                         *(unsigned long *)location = my_r2(sechdrs, me);
 833                         break;
 834
 835                 case R_PPC64_TOC16:
 836                         /* Subtract TOC pointer */
 837                         value -= my_r2(sechdrs, me);
 838                         if (value + 0x8000 > 0xffff) {
 839                                 pr_err("%s: bad TOC16 relocation (0x%lx)\n",
 840                                        me->name, value);
 841                                 return -ENOEXEC;
 842                         }
 843                         *((uint16_t *) location)
 844                                 = (*((uint16_t *) location) & ~0xffff)
 845                                 | (value & 0xffff);
 846                         break;
 847
 848                 case R_PPC64_TOC16_LO:
 849                         /* Subtract TOC pointer */
 850                         value -= my_r2(sechdrs, me);
 851                         *((uint16_t *) location)
 852                                 = (*((uint16_t *) location) & ~0xffff)
 853                                 | (value & 0xffff);
 854                         break;
 855
 856                 case R_PPC64_TOC16_DS:
 857                         /* Subtract TOC pointer */
 858                         value -= my_r2(sechdrs, me);
 859                         if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
 860                                 pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
 861                                        me->name, value);
 862                                 return -ENOEXEC;
 863                         }
 864                         *((uint16_t *) location)
 865                                 = (*((uint16_t *) location) & ~0xfffc)
 866                                 | (value & 0xfffc);
 867                         break;
 868
 869                 case R_PPC64_TOC16_LO_DS:
 870                         /* Subtract TOC pointer */
 871                         value -= my_r2(sechdrs, me);
 872                         if ((value & 3) != 0) {
 873                                 pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
 874                                        me->name, value);
 875                                 return -ENOEXEC;
 876                         }
 877                         *((uint16_t *) location)
 878                                 = (*((uint16_t *) location) & ~0xfffc)
 879                                 | (value & 0xfffc);
 880                         break;
 881
 882                 case R_PPC64_TOC16_HA:
 883                         /* Subtract TOC pointer */
 884                         value -= my_r2(sechdrs, me);
 885                         value = ((value + 0x8000) >> 16);
 886                         *((uint16_t *) location)
 887                                 = (*((uint16_t *) location) & ~0xffff)
 888                                 | (value & 0xffff);
 889                         break;
 890 #endif
 891
 892                 case R_PPC_REL24:
 893 #ifdef CONFIG_PPC_KERNEL_PCREL
 894                 /* PCREL still generates REL24 for mcount */
 895                 case R_PPC64_REL24_NOTOC:
 896 #endif
 897                         /* FIXME: Handle weak symbols here --RR */
 898                         if (sym->st_shndx == SHN_UNDEF ||
 899                             sym->st_shndx == SHN_LIVEPATCH) {
 900                                 /* External: go via stub */
 901                                 value = stub_for_addr(sechdrs, value, me,
 902                                                 strtab + sym->st_name);
 903                                 if (!value)
 904                                         return -ENOENT;
 905                                 if (restore_r2(strtab + sym->st_name,
 906                                                (u32 *)location + 1, me))
 907                                         return -ENOEXEC;
 908                         } else
 909                                 value += local_entry_offset(sym);
 910
 911                         /* Convert value to relative */
 912                         value -= (unsigned long)location;
 913                         if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
 914                                 pr_err("%s: REL24 %li out of range!\n",
 915                                        me->name, (long int)value);
 916                                 return -ENOEXEC;
 917                         }
 918
 919                         /* Only replace bits 2 through 26 */
 920                         value = (*(uint32_t *)location & ~PPC_LI_MASK) | PPC_LI(value);
 921
 922                         if (patch_instruction((u32 *)location, ppc_inst(value)))
 923                                 return -EFAULT;
 924
 925                         break;
 926
 927                 case R_PPC64_REL64:
 928                         /* 64 bits relative (used by features fixups) */
 929                         *location = value - (unsigned long)location;
 930                         break;
 931
 932                 case R_PPC64_REL32:
 933                         /* 32 bits relative (used by relative exception tables) */
 934                         /* Convert value to relative */
 935                         value -= (unsigned long)location;
 936                         if (value + 0x80000000 > 0xffffffff) {
 937                                 pr_err("%s: REL32 %li out of range!\n",
 938                                        me->name, (long int)value);
 939                                 return -ENOEXEC;
 940                         }
 941                         *(u32 *)location = value;
 942                         break;
 943
 944 #ifdef CONFIG_PPC_KERNEL_PCREL
 945                 case R_PPC64_PCREL34: {
 946                         unsigned long absvalue = value;
 947
 948                         /* Convert value to relative */
 949                         value -= (unsigned long)location;
 950
 951                         if (value + 0x200000000 > 0x3ffffffff) {
 952                                 if (sym->st_shndx != me->arch.pcpu_section) {
 953                                         pr_err("%s: REL34 %li out of range!\n",
 954                                                me->name, (long)value);
 955                                         return -ENOEXEC;
 956                                 }
 957
 958                                 /*
 959                                  * per-cpu section is special cased because
 960                                  * it is moved during loading, so has to be
 961                                  * converted to use GOT.
 962                                  */
 963                                 value = got_for_addr(sechdrs, absvalue, me,
 964                                                      strtab + sym->st_name);
 965                                 if (!value)
 966                                         return -ENOENT;
 967                                 value -= (unsigned long)location;
 968
 969                                 /* Turn pla into pld */
 970                                 if (patch_instruction((u32 *)location,
 971                                     ppc_inst_prefix((*(u32 *)location & ~0x02000000),
 972                                                     (*((u32 *)location + 1) & ~0xf8000000) | 0xe4000000)))
 973                                         return -EFAULT;
 974                         }
 975
 976                         if (patch_instruction((u32 *)location,
 977                             ppc_inst_prefix((*(u32 *)location & ~0x3ffff) | IMM_H18(value),
 978                                             (*((u32 *)location + 1) & ~0xffff) | IMM_L(value))))
 979                                 return -EFAULT;
 980
 981                         break;
 982                 }
 983
 984 #else
 985                 case R_PPC64_TOCSAVE:
 986                         /*
 987                          * Marker reloc indicates we don't have to save r2.
 988                          * That would only save us one instruction, so ignore
 989                          * it.
 990                          */
 991                         break;
 992 #endif
 993
 994                 case R_PPC64_ENTRY:
 995                         if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL))
 996                                 break;
 997
 998                         /*
 999                          * Optimize ELFv2 large code model entry point if
1000                          * the TOC is within 2GB range of current location.
1001                          */
1002                         value = my_r2(sechdrs, me) - (unsigned long)location;
1003                         if (value + 0x80008000 > 0xffffffff)
1004                                 break;
1005                         /*
1006                          * Check for the large code model prolog sequence:
1007                          *      ld r2, ...(r12)
1008                          *      add r2, r2, r12
1009                          */
1010                         if ((((uint32_t *)location)[0] & ~0xfffc) != PPC_RAW_LD(_R2, _R12, 0))
1011                                 break;
1012                         if (((uint32_t *)location)[1] != PPC_RAW_ADD(_R2, _R2, _R12))
1013                                 break;
1014                         /*
1015                          * If found, replace it with:
1016                          *      addis r2, r12, (.TOC.-func)@ha
1017                          *      addi  r2,  r2, (.TOC.-func)@l
1018                          */
1019                         ((uint32_t *)location)[0] = PPC_RAW_ADDIS(_R2, _R12, PPC_HA(value));
1020                         ((uint32_t *)location)[1] = PPC_RAW_ADDI(_R2, _R2, PPC_LO(value));
1021                         break;
1022
1023                 case R_PPC64_REL16_HA:
1024                         /* Subtract location pointer */
1025                         value -= (unsigned long)location;
1026                         value = ((value + 0x8000) >> 16);
1027                         *((uint16_t *) location)
1028                                 = (*((uint16_t *) location) & ~0xffff)
1029                                 | (value & 0xffff);
1030                         break;
1031
1032                 case R_PPC64_REL16_LO:
1033                         /* Subtract location pointer */
1034                         value -= (unsigned long)location;
1035                         *((uint16_t *) location)
1036                                 = (*((uint16_t *) location) & ~0xffff)
1037                                 | (value & 0xffff);
1038                         break;
1039
1040 #ifdef CONFIG_PPC_KERNEL_PCREL
1041                 case R_PPC64_GOT_PCREL34:
1042                         value = got_for_addr(sechdrs, value, me,
1043                                              strtab + sym->st_name);
1044                         if (!value)
1045                                 return -ENOENT;
1046                         value -= (unsigned long)location;
1047                         ((uint32_t *)location)[0] = (((uint32_t *)location)[0] & ~0x3ffff) |
1048                                                     ((value >> 16) & 0x3ffff);
1049                         ((uint32_t *)location)[1] = (((uint32_t *)location)[1] & ~0xffff) |
1050                                                     (value & 0xffff);
1051                         break;
1052 #endif
1053
1054                 default:
1055                         pr_err("%s: Unknown ADD relocation: %lu\n",
1056                                me->name,
1057                                (unsigned long)ELF64_R_TYPE(rela[i].r_info));
1058                         return -ENOEXEC;
1059                 }
1060         }
1061
1062         return 0;
1063 }
1064
1065 #ifdef CONFIG_DYNAMIC_FTRACE
1066 int module_trampoline_target(struct module *mod, unsigned long addr,
1067                              unsigned long *target)
1068 {
1069         struct ppc64_stub_entry *stub;
1070         func_desc_t funcdata;
1071         u32 magic;
1072
1073         if (!within_module_core(addr, mod)) {
1074                 pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name);
1075                 return -EFAULT;
1076         }
1077
1078         stub = (struct ppc64_stub_entry *)addr;
1079
1080         if (copy_from_kernel_nofault(&magic, &stub->magic,
1081                         sizeof(magic))) {
1082                 pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name);
1083                 return -EFAULT;
1084         }
1085
1086         if (magic != STUB_MAGIC) {
1087                 pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name);
1088                 return -EFAULT;
1089         }
1090
1091         if (copy_from_kernel_nofault(&funcdata, &stub->funcdata,
1092                         sizeof(funcdata))) {
1093                 pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name);
1094                 return -EFAULT;
1095         }
1096
1097         *target = stub_func_addr(funcdata);
1098
1099         return 0;
1100 }
1101
1102 static int setup_ftrace_ool_stubs(const Elf64_Shdr *sechdrs, unsigned long addr, struct module *me)
1103 {
1104 #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
1105         unsigned int i, total_stubs, num_stubs;
1106         struct ppc64_stub_entry *stub;
1107
1108         total_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stub);
1109         num_stubs = roundup(me->arch.ool_stub_count * sizeof(struct ftrace_ool_stub),
1110                             sizeof(struct ppc64_stub_entry)) / sizeof(struct ppc64_stub_entry);
1111
1112         /* Find the next available entry */
1113         stub = (void *)sechdrs[me->arch.stubs_section].sh_addr;
1114         for (i = 0; stub_func_addr(stub[i].funcdata); i++)
1115                 if (WARN_ON(i >= total_stubs))
1116                         return -1;
1117
1118         if (WARN_ON(i + num_stubs > total_stubs))
1119                 return -1;
1120
1121         stub += i;
1122         me->arch.ool_stubs = (struct ftrace_ool_stub *)stub;
1123
1124         /* reserve stubs */
1125         for (i = 0; i < num_stubs; i++)
1126                 if (patch_u32((void *)&stub->funcdata, PPC_RAW_NOP()))
1127                         return -1;
1128 #endif
1129
1130         return 0;
1131 }
1132
1133 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
1134 {
1135         mod->arch.tramp = stub_for_addr(sechdrs,
1136                                         (unsigned long)ftrace_caller,
1137                                         mod,
1138                                         "ftrace_caller");
1139 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
1140         mod->arch.tramp_regs = stub_for_addr(sechdrs,
1141                                         (unsigned long)ftrace_regs_caller,
1142                                         mod,
1143                                         "ftrace_regs_caller");
1144         if (!mod->arch.tramp_regs)
1145                 return -ENOENT;
1146 #endif
1147
1148         if (!mod->arch.tramp)
1149                 return -ENOENT;
1150
1151         if (setup_ftrace_ool_stubs(sechdrs, mod->arch.tramp, mod))
1152                 return -ENOENT;
1153
1154         return 0;
1155 }
1156 #endif