arch/powerpc/kernel/module

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
func_addr
stub_func_addr
local_entry_offset
func_addr
stub_func_addr
local_entry_offset
dereference_module_function_descriptor
module_trampoline_target
count_relocs
relacmp
relaswap
get_stubs_size
dedotify_versions
dedotify
find_dot_toc
module_frob_arch_sections
my_r2
create_stub
stub_for_addr
is_mprofile_mcount_callsite
squash_toc_save_inst
squash_toc_save_inst
is_mprofile_mcount_callsite
restore_r2
apply_relocate_add
create_ftrace_stub
create_ftrace_stub
module_finalize_ftrace
   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
/* [<][>][^][v][top][bottom][index][help] */
root/arch/powerpc/kernel/module_64.c

DEFINITIONS
