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 <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 #include <asm/inst.h>
  24
  25 /* FIXME: We don't do .init separately.  To do this, we'd need to have
  26    a separate r2 value in the init and core section, and stub between
  27    them, too.
  28
  29    Using a magic allocator which places modules within 32MB solves
  30    this, and makes other things simpler.  Anton?
  31    --RR.  */
  32
  33 #ifdef PPC64_ELF_ABI_v2
  34
  35 /* An address is simply the address of the function. */
  36 typedef unsigned long func_desc_t;
  37
  38 static func_desc_t func_desc(unsigned long addr)
  39 {
  40         return addr;
  41 }
  42 static unsigned long func_addr(unsigned long addr)
  43 {
  44         return addr;
  45 }
  46 static unsigned long stub_func_addr(func_desc_t func)
  47 {
  48         return func;
  49 }
  50
  51 /* PowerPC64 specific values for the Elf64_Sym st_other field.  */
  52 #define STO_PPC64_LOCAL_BIT     5
  53 #define STO_PPC64_LOCAL_MASK    (7 << STO_PPC64_LOCAL_BIT)
  54 #define PPC64_LOCAL_ENTRY_OFFSET(other)                                 \
  55  (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
  56
  57 static unsigned int local_entry_offset(const Elf64_Sym *sym)
  58 {
  59         /* sym->st_other indicates offset to local entry point
  60          * (otherwise it will assume r12 is the address of the start
  61          * of function and try to derive r2 from it). */
  62         return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
  63 }
  64 #else
  65
  66 /* An address is address of the OPD entry, which contains address of fn. */
  67 typedef struct ppc64_opd_entry func_desc_t;
  68
  69 static func_desc_t func_desc(unsigned long addr)
  70 {
  71         return *(struct ppc64_opd_entry *)addr;
  72 }
  73 static unsigned long func_addr(unsigned long addr)
  74 {
  75         return func_desc(addr).funcaddr;
  76 }
  77 static unsigned long stub_func_addr(func_desc_t func)
  78 {
  79         return func.funcaddr;
  80 }
  81 static unsigned int local_entry_offset(const Elf64_Sym *sym)
  82 {
  83         return 0;
  84 }
  85
  86 void *dereference_module_function_descriptor(struct module *mod, void *ptr)
  87 {
  88         if (ptr < (void *)mod->arch.start_opd ||
  89                         ptr >= (void *)mod->arch.end_opd)
  90                 return ptr;
  91
  92         return dereference_function_descriptor(ptr);
  93 }
  94 #endif
  95
  96 #define STUB_MAGIC 0x73747562 /* stub */
  97
  98 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into
  99    the kernel itself).  But on PPC64, these need to be used for every
 100    jump, actually, to reset r2 (TOC+0x8000). */
 101 struct ppc64_stub_entry
 102 {
 103         /* 28 byte jump instruction sequence (7 instructions). We only
 104          * need 6 instructions on ABIv2 but we always allocate 7 so
 105          * so we don't have to modify the trampoline load instruction. */
 106         u32 jump[7];
 107         /* Used by ftrace to identify stubs */
 108         u32 magic;
 109         /* Data for the above code */
 110         func_desc_t funcdata;
 111 };
 112
 113 /*
 114  * PPC64 uses 24 bit jumps, but we need to jump into other modules or
 115  * the kernel which may be further.  So we jump to a stub.
 116  *
 117  * For ELFv1 we need to use this to set up the new r2 value (aka TOC
 118  * pointer).  For ELFv2 it's the callee's responsibility to set up the
 119  * new r2, but for both we need to save the old r2.
 120  *
 121  * We could simply patch the new r2 value and function pointer into
 122  * the stub, but it's significantly shorter to put these values at the
 123  * end of the stub code, and patch the stub address (32-bits relative
 124  * to the TOC ptr, r2) into the stub.
 125  */
 126 static u32 ppc64_stub_insns[] = {
 127         PPC_RAW_ADDIS(_R11, _R2, 0),
 128         PPC_RAW_ADDI(_R11, _R11, 0),
 129         /* Save current r2 value in magic place on the stack. */
 130         PPC_RAW_STD(_R2, _R1, R2_STACK_OFFSET),
 131         PPC_RAW_LD(_R12, _R11, 32),
 132 #ifdef PPC64_ELF_ABI_v1
 133         /* Set up new r2 from function descriptor */
 134         PPC_RAW_LD(_R2, _R11, 40),
 135 #endif
 136         PPC_RAW_MTCTR(_R12),
 137         PPC_RAW_BCTR(),
 138 };
 139
 140 /* Count how many different 24-bit relocations (different symbol,
 141    different addend) */
 142 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num)
 143 {
 144         unsigned int i, r_info, r_addend, _count_relocs;
 145
 146         /* FIXME: Only count external ones --RR */
 147         _count_relocs = 0;
 148         r_info = 0;
 149         r_addend = 0;
 150         for (i = 0; i < num; i++)
 151                 /* Only count 24-bit relocs, others don't need stubs */
 152                 if (ELF64_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
 153                     (r_info != ELF64_R_SYM(rela[i].r_info) ||
 154                      r_addend != rela[i].r_addend)) {
 155                         _count_relocs++;
 156                         r_info = ELF64_R_SYM(rela[i].r_info);
 157                         r_addend = rela[i].r_addend;
 158                 }
 159
 160         return _count_relocs;
 161 }
 162
 163 static int relacmp(const void *_x, const void *_y)
 164 {
 165         const Elf64_Rela *x, *y;
 166
 167         y = (Elf64_Rela *)_x;
 168         x = (Elf64_Rela *)_y;
 169
 170         /* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to
 171          * make the comparison cheaper/faster. It won't affect the sorting or
 172          * the counting algorithms' performance
 173          */
 174         if (x->r_info < y->r_info)
 175                 return -1;
 176         else if (x->r_info > y->r_info)
 177                 return 1;
 178         else if (x->r_addend < y->r_addend)
 179                 return -1;
 180         else if (x->r_addend > y->r_addend)
 181                 return 1;
 182         else
 183                 return 0;
 184 }
 185
 186 /* Get size of potential trampolines required. */
 187 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
 188                                     const Elf64_Shdr *sechdrs)
 189 {
 190         /* One extra reloc so it's always 0-funcaddr terminated */
 191         unsigned long relocs = 1;
 192         unsigned i;
 193
 194         /* Every relocated section... */
 195         for (i = 1; i < hdr->e_shnum; i++) {
 196                 if (sechdrs[i].sh_type == SHT_RELA) {
 197                         pr_debug("Found relocations in section %u\n", i);
 198                         pr_debug("Ptr: %p.  Number: %Lu\n",
 199                                (void *)sechdrs[i].sh_addr,
 200                                sechdrs[i].sh_size / sizeof(Elf64_Rela));
 201
 202                         /* Sort the relocation information based on a symbol and
 203                          * addend key. This is a stable O(n*log n) complexity
 204                          * alogrithm but it will reduce the complexity of
 205                          * count_relocs() to linear complexity O(n)
 206                          */
 207                         sort((void *)sechdrs[i].sh_addr,
 208                              sechdrs[i].sh_size / sizeof(Elf64_Rela),
 209                              sizeof(Elf64_Rela), relacmp, NULL);
 210
 211                         relocs += count_relocs((void *)sechdrs[i].sh_addr,
 212                                                sechdrs[i].sh_size
 213                                                / sizeof(Elf64_Rela));
 214                 }
 215         }
 216
 217 #ifdef CONFIG_DYNAMIC_FTRACE
 218         /* make the trampoline to the ftrace_caller */
 219         relocs++;
 220 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 221         /* an additional one for ftrace_regs_caller */
 222         relocs++;
 223 #endif
 224 #endif
 225
 226         pr_debug("Looks like a total of %lu stubs, max\n", relocs);
 227         return relocs * sizeof(struct ppc64_stub_entry);
 228 }
 229
 230 /* Still needed for ELFv2, for .TOC. */
 231 static void dedotify_versions(struct modversion_info *vers,
 232                               unsigned long size)
 233 {
 234         struct modversion_info *end;
 235
 236         for (end = (void *)vers + size; vers < end; vers++)
 237                 if (vers->name[0] == '.') {
 238                         memmove(vers->name, vers->name+1, strlen(vers->name));
 239                 }
 240 }
 241
 242 /*
 243  * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
 244  * seem to be defined (value set later).
 245  */
 246 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
 247 {
 248         unsigned int i;
 249
 250         for (i = 1; i < numsyms; i++) {
 251                 if (syms[i].st_shndx == SHN_UNDEF) {
 252                         char *name = strtab + syms[i].st_name;
 253                         if (name[0] == '.') {
 254                                 if (strcmp(name+1, "TOC.") == 0)
 255                                         syms[i].st_shndx = SHN_ABS;
 256                                 syms[i].st_name++;
 257                         }
 258                 }
 259         }
 260 }
 261
 262 static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
 263                                const char *strtab,
 264                                unsigned int symindex)
 265 {
 266         unsigned int i, numsyms;
 267         Elf64_Sym *syms;
 268
 269         syms = (Elf64_Sym *)sechdrs[symindex].sh_addr;
 270         numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
 271
 272         for (i = 1; i < numsyms; i++) {
 273                 if (syms[i].st_shndx == SHN_ABS
 274                     && strcmp(strtab + syms[i].st_name, "TOC.") == 0)
 275                         return &syms[i];
 276         }
 277         return NULL;
 278 }
 279
 280 int module_frob_arch_sections(Elf64_Ehdr *hdr,
 281                               Elf64_Shdr *sechdrs,
 282                               char *secstrings,
 283                               struct module *me)
 284 {
 285         unsigned int i;
 286
 287         /* Find .toc and .stubs sections, symtab and strtab */
 288         for (i = 1; i < hdr->e_shnum; i++) {
 289                 char *p;
 290                 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
 291                         me->arch.stubs_section = i;
 292                 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) {
 293                         me->arch.toc_section = i;
 294                         if (sechdrs[i].sh_addralign < 8)
 295                                 sechdrs[i].sh_addralign = 8;
 296                 }
 297                 else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
 298                         dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
 299                                           sechdrs[i].sh_size);
 300
 301                 /* We don't handle .init for the moment: rename to _init */
 302                 while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
 303                         p[0] = '_';
 304
 305                 if (sechdrs[i].sh_type == SHT_SYMTAB)
 306                         dedotify((void *)hdr + sechdrs[i].sh_offset,
 307                                  sechdrs[i].sh_size / sizeof(Elf64_Sym),
 308                                  (void *)hdr
 309                                  + sechdrs[sechdrs[i].sh_link].sh_offset);
 310         }
 311
 312         if (!me->arch.stubs_section) {
 313                 pr_err("%s: doesn't contain .stubs.\n", me->name);
 314                 return -ENOEXEC;
 315         }
 316
 317         /* If we don't have a .toc, just use .stubs.  We need to set r2
 318            to some reasonable value in case the module calls out to
 319            other functions via a stub, or if a function pointer escapes
 320            the module by some means.  */
 321         if (!me->arch.toc_section)
 322                 me->arch.toc_section = me->arch.stubs_section;
 323
 324         /* Override the stubs size */
 325         sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
 326         return 0;
 327 }
 328
 329 #ifdef CONFIG_MPROFILE_KERNEL
 330
 331 static u32 stub_insns[] = {
 332         PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
 333         PPC_RAW_ADDIS(_R12, _R12, 0),
 334         PPC_RAW_ADDI(_R12, _R12, 0),
 335         PPC_RAW_MTCTR(_R12),
 336         PPC_RAW_BCTR(),
 337 };
 338
 339 /*
 340  * For mprofile-kernel we use a special stub for ftrace_caller() because we
 341  * can't rely on r2 containing this module's TOC when we enter the stub.
 342  *
 343  * That can happen if the function calling us didn't need to use the toc. In
 344  * that case it won't have setup r2, and the r2 value will be either the
 345  * kernel's toc, or possibly another modules toc.
 346  *
 347  * To deal with that this stub uses the kernel toc, which is always accessible
 348  * via the paca (in r13). The target (ftrace_caller()) is responsible for
 349  * saving and restoring the toc before returning.
 350  */
 351 static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
 352                                         unsigned long addr,
 353                                         struct module *me)
 354 {
 355         long reladdr;
 356
 357         memcpy(entry->jump, stub_insns, sizeof(stub_insns));
 358
 359         /* Stub uses address relative to kernel toc (from the paca) */
 360         reladdr = addr - kernel_toc_addr();
 361         if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
 362                 pr_err("%s: Address of %ps out of range of kernel_toc.\n",
 363                                                         me->name, (void *)addr);
 364                 return 0;
 365         }
 366
 367         entry->jump[1] |= PPC_HA(reladdr);
 368         entry->jump[2] |= PPC_LO(reladdr);
 369
 370         /* Eventhough we don't use funcdata in the stub, it's needed elsewhere. */
 371         entry->funcdata = func_desc(addr);
 372         entry->magic = STUB_MAGIC;
 373
 374         return 1;
 375 }
 376
 377 static bool is_mprofile_ftrace_call(const char *name)
 378 {
 379         if (!strcmp("_mcount", name))
 380                 return true;
 381 #ifdef CONFIG_DYNAMIC_FTRACE
 382         if (!strcmp("ftrace_caller", name))
 383                 return true;
 384 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 385         if (!strcmp("ftrace_regs_caller", name))
 386                 return true;
 387 #endif
 388 #endif
 389
 390         return false;
 391 }
 392 #else
 393 static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
 394                                         unsigned long addr,
 395                                         struct module *me)
 396 {
 397         return 0;
 398 }
 399
 400 static bool is_mprofile_ftrace_call(const char *name)
 401 {
 402         return false;
 403 }
 404 #endif
 405
 406 /*
 407  * r2 is the TOC pointer: it actually points 0x8000 into the TOC (this gives the
 408  * value maximum span in an instruction which uses a signed offset). Round down
 409  * to a 256 byte boundary for the odd case where we are setting up r2 without a
 410  * .toc section.
 411  */
 412 static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me)
 413 {
 414         return (sechdrs[me->arch.toc_section].sh_addr & ~0xfful) + 0x8000;
 415 }
 416
 417 /* Patch stub to reference function and correct r2 value. */
 418 static inline int create_stub(const Elf64_Shdr *sechdrs,
 419                               struct ppc64_stub_entry *entry,
 420                               unsigned long addr,
 421                               struct module *me,
 422                               const char *name)
 423 {
 424         long reladdr;
 425
 426         if (is_mprofile_ftrace_call(name))
 427                 return create_ftrace_stub(entry, addr, me);
 428
 429         memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns));
 430
 431         /* Stub uses address relative to r2. */
 432         reladdr = (unsigned long)entry - my_r2(sechdrs, me);
 433         if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
 434                 pr_err("%s: Address %p of stub out of range of %p.\n",
 435                        me->name, (void *)reladdr, (void *)my_r2);
 436                 return 0;
 437         }
 438         pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
 439
 440         entry->jump[0] |= PPC_HA(reladdr);
 441         entry->jump[1] |= PPC_LO(reladdr);
 442         entry->funcdata = func_desc(addr);
 443         entry->magic = STUB_MAGIC;
 444
 445         return 1;
 446 }
 447
 448 /* Create stub to jump to function described in this OPD/ptr: we need the
 449    stub to set up the TOC ptr (r2) for the function. */
 450 static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
 451                                    unsigned long addr,
 452                                    struct module *me,
 453                                    const char *name)
 454 {
 455         struct ppc64_stub_entry *stubs;
 456         unsigned int i, num_stubs;
 457
 458         num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
 459
 460         /* Find this stub, or if that fails, the next avail. entry */
 461         stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
 462         for (i = 0; stub_func_addr(stubs[i].funcdata); i++) {
 463                 if (WARN_ON(i >= num_stubs))
 464                         return 0;
 465
 466                 if (stub_func_addr(stubs[i].funcdata) == func_addr(addr))
 467                         return (unsigned long)&stubs[i];
 468         }
 469
 470         if (!create_stub(sechdrs, &stubs[i], addr, me, name))
 471                 return 0;
 472
 473         return (unsigned long)&stubs[i];
 474 }
 475
 476 /* We expect a noop next: if it is, replace it with instruction to
 477    restore r2. */
 478 static int restore_r2(const char *name, u32 *instruction, struct module *me)
 479 {
 480         u32 *prev_insn = instruction - 1;
 481
 482         if (is_mprofile_ftrace_call(name))
 483                 return 1;
 484
 485         /*
 486          * Make sure the branch isn't a sibling call.  Sibling calls aren't
 487          * "link" branches and they don't return, so they don't need the r2
 488          * restore afterwards.
 489          */
 490         if (!instr_is_relative_link_branch(ppc_inst(*prev_insn)))
 491                 return 1;
 492
 493         if (*instruction != PPC_RAW_NOP()) {
 494                 pr_err("%s: Expected nop after call, got %08x at %pS\n",
 495                         me->name, *instruction, instruction);
 496                 return 0;
 497         }
 498         /* ld r2,R2_STACK_OFFSET(r1) */
 499         *instruction = PPC_INST_LD_TOC;
 500         return 1;
 501 }
 502
 503 int apply_relocate_add(Elf64_Shdr *sechdrs,
 504                        const char *strtab,
 505                        unsigned int symindex,
 506                        unsigned int relsec,
 507                        struct module *me)
 508 {
 509         unsigned int i;
 510         Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
 511         Elf64_Sym *sym;
 512         unsigned long *location;
 513         unsigned long value;
 514
 515         pr_debug("Applying ADD relocate section %u to %u\n", relsec,
 516                sechdrs[relsec].sh_info);
 517
 518         /* First time we're called, we can fix up .TOC. */
 519         if (!me->arch.toc_fixed) {
 520                 sym = find_dot_toc(sechdrs, strtab, symindex);
 521                 /* It's theoretically possible that a module doesn't want a
 522                  * .TOC. so don't fail it just for that. */
 523                 if (sym)
 524                         sym->st_value = my_r2(sechdrs, me);
 525                 me->arch.toc_fixed = true;
 526         }
 527
 528         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
 529                 /* This is where to make the change */
 530                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 531                         + rela[i].r_offset;
 532                 /* This is the symbol it is referring to */
 533                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
 534                         + ELF64_R_SYM(rela[i].r_info);
 535
 536                 pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
 537                        location, (long)ELF64_R_TYPE(rela[i].r_info),
 538                        strtab + sym->st_name, (unsigned long)sym->st_value,
 539                        (long)rela[i].r_addend);
 540
 541                 /* `Everything is relative'. */
 542                 value = sym->st_value + rela[i].r_addend;
 543
 544                 switch (ELF64_R_TYPE(rela[i].r_info)) {
 545                 case R_PPC64_ADDR32:
 546                         /* Simply set it */
 547                         *(u32 *)location = value;
 548                         break;
 549
 550                 case R_PPC64_ADDR64:
 551                         /* Simply set it */
 552                         *(unsigned long *)location = value;
 553                         break;
 554
 555                 case R_PPC64_TOC:
 556                         *(unsigned long *)location = my_r2(sechdrs, me);
 557                         break;
 558
 559                 case R_PPC64_TOC16:
 560                         /* Subtract TOC pointer */
 561                         value -= my_r2(sechdrs, me);
 562                         if (value + 0x8000 > 0xffff) {
 563                                 pr_err("%s: bad TOC16 relocation (0x%lx)\n",
 564                                        me->name, value);
 565                                 return -ENOEXEC;
 566                         }
 567                         *((uint16_t *) location)
 568                                 = (*((uint16_t *) location) & ~0xffff)
 569                                 | (value & 0xffff);
 570                         break;
 571
 572                 case R_PPC64_TOC16_LO:
 573                         /* Subtract TOC pointer */
 574                         value -= my_r2(sechdrs, me);
 575                         *((uint16_t *) location)
 576                                 = (*((uint16_t *) location) & ~0xffff)
 577                                 | (value & 0xffff);
 578                         break;
 579
 580                 case R_PPC64_TOC16_DS:
 581                         /* Subtract TOC pointer */
 582                         value -= my_r2(sechdrs, me);
 583                         if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
 584                                 pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
 585                                        me->name, value);
 586                                 return -ENOEXEC;
 587                         }
 588                         *((uint16_t *) location)
 589                                 = (*((uint16_t *) location) & ~0xfffc)
 590                                 | (value & 0xfffc);
 591                         break;
 592
 593                 case R_PPC64_TOC16_LO_DS:
 594                         /* Subtract TOC pointer */
 595                         value -= my_r2(sechdrs, me);
 596                         if ((value & 3) != 0) {
 597                                 pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
 598                                        me->name, value);
 599                                 return -ENOEXEC;
 600                         }
 601                         *((uint16_t *) location)
 602                                 = (*((uint16_t *) location) & ~0xfffc)
 603                                 | (value & 0xfffc);
 604                         break;
 605
 606                 case R_PPC64_TOC16_HA:
 607                         /* Subtract TOC pointer */
 608                         value -= my_r2(sechdrs, me);
 609                         value = ((value + 0x8000) >> 16);
 610                         *((uint16_t *) location)
 611                                 = (*((uint16_t *) location) & ~0xffff)
 612                                 | (value & 0xffff);
 613                         break;
 614
 615                 case R_PPC_REL24:
 616                         /* FIXME: Handle weak symbols here --RR */
 617                         if (sym->st_shndx == SHN_UNDEF ||
 618                             sym->st_shndx == SHN_LIVEPATCH) {
 619                                 /* External: go via stub */
 620                                 value = stub_for_addr(sechdrs, value, me,
 621                                                 strtab + sym->st_name);
 622                                 if (!value)
 623                                         return -ENOENT;
 624                                 if (!restore_r2(strtab + sym->st_name,
 625                                                         (u32 *)location + 1, me))
 626                                         return -ENOEXEC;
 627                         } else
 628                                 value += local_entry_offset(sym);
 629
 630                         /* Convert value to relative */
 631                         value -= (unsigned long)location;
 632                         if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
 633                                 pr_err("%s: REL24 %li out of range!\n",
 634                                        me->name, (long int)value);
 635                                 return -ENOEXEC;
 636                         }
 637
 638                         /* Only replace bits 2 through 26 */
 639                         *(uint32_t *)location
 640                                 = (*(uint32_t *)location & ~0x03fffffc)
 641                                 | (value & 0x03fffffc);
 642                         break;
 643
 644                 case R_PPC64_REL64:
 645                         /* 64 bits relative (used by features fixups) */
 646                         *location = value - (unsigned long)location;
 647                         break;
 648
 649                 case R_PPC64_REL32:
 650                         /* 32 bits relative (used by relative exception tables) */
 651                         /* Convert value to relative */
 652                         value -= (unsigned long)location;
 653                         if (value + 0x80000000 > 0xffffffff) {
 654                                 pr_err("%s: REL32 %li out of range!\n",
 655                                        me->name, (long int)value);
 656                                 return -ENOEXEC;
 657                         }
 658                         *(u32 *)location = value;
 659                         break;
 660
 661                 case R_PPC64_TOCSAVE:
 662                         /*
 663                          * Marker reloc indicates we don't have to save r2.
 664                          * That would only save us one instruction, so ignore
 665                          * it.
 666                          */
 667                         break;
 668
 669                 case R_PPC64_ENTRY:
 670                         /*
 671                          * Optimize ELFv2 large code model entry point if
 672                          * the TOC is within 2GB range of current location.
 673                          */
 674                         value = my_r2(sechdrs, me) - (unsigned long)location;
 675                         if (value + 0x80008000 > 0xffffffff)
 676                                 break;
 677                         /*
 678                          * Check for the large code model prolog sequence:
 679                          *      ld r2, ...(r12)
 680                          *      add r2, r2, r12
 681                          */
 682                         if ((((uint32_t *)location)[0] & ~0xfffc) != PPC_RAW_LD(_R2, _R12, 0))
 683                                 break;
 684                         if (((uint32_t *)location)[1] != PPC_RAW_ADD(_R2, _R2, _R12))
 685                                 break;
 686                         /*
 687                          * If found, replace it with:
 688                          *      addis r2, r12, (.TOC.-func)@ha
 689                          *      addi  r2,  r2, (.TOC.-func)@l
 690                          */
 691                         ((uint32_t *)location)[0] = PPC_RAW_ADDIS(_R2, _R12, PPC_HA(value));
 692                         ((uint32_t *)location)[1] = PPC_RAW_ADDI(_R2, _R2, PPC_LO(value));
 693                         break;
 694
 695                 case R_PPC64_REL16_HA:
 696                         /* Subtract location pointer */
 697                         value -= (unsigned long)location;
 698                         value = ((value + 0x8000) >> 16);
 699                         *((uint16_t *) location)
 700                                 = (*((uint16_t *) location) & ~0xffff)
 701                                 | (value & 0xffff);
 702                         break;
 703
 704                 case R_PPC64_REL16_LO:
 705                         /* Subtract location pointer */
 706                         value -= (unsigned long)location;
 707                         *((uint16_t *) location)
 708                                 = (*((uint16_t *) location) & ~0xffff)
 709                                 | (value & 0xffff);
 710                         break;
 711
 712                 default:
 713                         pr_err("%s: Unknown ADD relocation: %lu\n",
 714                                me->name,
 715                                (unsigned long)ELF64_R_TYPE(rela[i].r_info));
 716                         return -ENOEXEC;
 717                 }
 718         }
 719
 720         return 0;
 721 }
 722
 723 #ifdef CONFIG_DYNAMIC_FTRACE
 724 int module_trampoline_target(struct module *mod, unsigned long addr,
 725                              unsigned long *target)
 726 {
 727         struct ppc64_stub_entry *stub;
 728         func_desc_t funcdata;
 729         u32 magic;
 730
 731         if (!within_module_core(addr, mod)) {
 732                 pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name);
 733                 return -EFAULT;
 734         }
 735
 736         stub = (struct ppc64_stub_entry *)addr;
 737
 738         if (copy_from_kernel_nofault(&magic, &stub->magic,
 739                         sizeof(magic))) {
 740                 pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name);
 741                 return -EFAULT;
 742         }
 743
 744         if (magic != STUB_MAGIC) {
 745                 pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name);
 746                 return -EFAULT;
 747         }
 748
 749         if (copy_from_kernel_nofault(&funcdata, &stub->funcdata,
 750                         sizeof(funcdata))) {
 751                 pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name);
 752                 return -EFAULT;
 753         }
 754
 755         *target = stub_func_addr(funcdata);
 756
 757         return 0;
 758 }
 759
 760 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
 761 {
 762         mod->arch.tramp = stub_for_addr(sechdrs,
 763                                         (unsigned long)ftrace_caller,
 764                                         mod,
 765                                         "ftrace_caller");
 766 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 767         mod->arch.tramp_regs = stub_for_addr(sechdrs,
 768                                         (unsigned long)ftrace_regs_caller,
 769                                         mod,
 770                                         "ftrace_regs_caller");
 771         if (!mod->arch.tramp_regs)
 772                 return -ENOENT;
 773 #endif
 774
 775         if (!mod->arch.tramp)
 776                 return -ENOENT;
 777
 778         return 0;
 779 }
 780 #endif