arch/powerpc/kernel/module_64.c

   1 /*  Kernel module help for PPC64.
   2     Copyright (C) 2001, 2003 Rusty Russell IBM Corporation.
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17 */
  18 #include <linux/module.h>
  19 #include <linux/elf.h>
  20 #include <linux/moduleloader.h>
  21 #include <linux/err.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/ftrace.h>
  24 #include <linux/bug.h>
  25 #include <asm/module.h>
  26 #include <asm/firmware.h>
  27 #include <asm/code-patching.h>
  28 #include <linux/sort.h>
  29 #include <asm/setup.h>
  30
  31 /* FIXME: We don't do .init separately.  To do this, we'd need to have
  32    a separate r2 value in the init and core section, and stub between
  33    them, too.
  34
  35    Using a magic allocator which places modules within 32MB solves
  36    this, and makes other things simpler.  Anton?
  37    --RR.  */
  38 #if 0
  39 #define DEBUGP printk
  40 #else
  41 #define DEBUGP(fmt , ...)
  42 #endif
  43
  44 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into
  45    the kernel itself).  But on PPC64, these need to be used for every
  46    jump, actually, to reset r2 (TOC+0x8000). */
  47 struct ppc64_stub_entry
  48 {
  49         /* 28 byte jump instruction sequence (7 instructions) */
  50         u32 jump[7];
  51         u32 unused;
  52         /* Data for the above code */
  53         struct ppc64_opd_entry opd;
  54 };
  55
  56 /* We use a stub to fix up r2 (TOC ptr) and to jump to the (external)
  57    function which may be more than 24-bits away.  We could simply
  58    patch the new r2 value and function pointer into the stub, but it's
  59    significantly shorter to put these values at the end of the stub
  60    code, and patch the stub address (32-bits relative to the TOC ptr,
  61    r2) into the stub. */
  62 static struct ppc64_stub_entry ppc64_stub =
  63 { .jump = {
  64         0x3d820000, /* addis   r12,r2, <high> */
  65         0x398c0000, /* addi    r12,r12, <low> */
  66         /* Save current r2 value in magic place on the stack. */
  67         0xf8410028, /* std     r2,40(r1) */
  68         0xe96c0020, /* ld      r11,32(r12) */
  69         0xe84c0028, /* ld      r2,40(r12) */
  70         0x7d6903a6, /* mtctr   r11 */
  71         0x4e800420  /* bctr */
  72 } };
  73
  74 /* Count how many different 24-bit relocations (different symbol,
  75    different addend) */
  76 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num)
  77 {
  78         unsigned int i, r_info, r_addend, _count_relocs;
  79
  80         /* FIXME: Only count external ones --RR */
  81         _count_relocs = 0;
  82         r_info = 0;
  83         r_addend = 0;
  84         for (i = 0; i < num; i++)
  85                 /* Only count 24-bit relocs, others don't need stubs */
  86                 if (ELF64_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
  87                     (r_info != ELF64_R_SYM(rela[i].r_info) ||
  88                      r_addend != rela[i].r_addend)) {
  89                         _count_relocs++;
  90                         r_info = ELF64_R_SYM(rela[i].r_info);
  91                         r_addend = rela[i].r_addend;
  92                 }
  93
  94         return _count_relocs;
  95 }
  96
  97 static int relacmp(const void *_x, const void *_y)
  98 {
  99         const Elf64_Rela *x, *y;
 100
 101         y = (Elf64_Rela *)_x;
 102         x = (Elf64_Rela *)_y;
 103
 104         /* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to
 105          * make the comparison cheaper/faster. It won't affect the sorting or
 106          * the counting algorithms' performance
 107          */
 108         if (x->r_info < y->r_info)
 109                 return -1;
 110         else if (x->r_info > y->r_info)
 111                 return 1;
 112         else if (x->r_addend < y->r_addend)
 113                 return -1;
 114         else if (x->r_addend > y->r_addend)
 115                 return 1;
 116         else
 117                 return 0;
 118 }
 119
 120 static void relaswap(void *_x, void *_y, int size)
 121 {
 122         uint64_t *x, *y, tmp;
 123         int i;
 124
 125         y = (uint64_t *)_x;
 126         x = (uint64_t *)_y;
 127
 128         for (i = 0; i < sizeof(Elf64_Rela) / sizeof(uint64_t); i++) {
 129                 tmp = x[i];
 130                 x[i] = y[i];
 131                 y[i] = tmp;
 132         }
 133 }
 134
 135 /* Get size of potential trampolines required. */
 136 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
 137                                     const Elf64_Shdr *sechdrs)
 138 {
 139         /* One extra reloc so it's always 0-funcaddr terminated */
 140         unsigned long relocs = 1;
 141         unsigned i;
 142
 143         /* Every relocated section... */
 144         for (i = 1; i < hdr->e_shnum; i++) {
 145                 if (sechdrs[i].sh_type == SHT_RELA) {
 146                         DEBUGP("Found relocations in section %u\n", i);
 147                         DEBUGP("Ptr: %p.  Number: %lu\n",
 148                                (void *)sechdrs[i].sh_addr,
 149                                sechdrs[i].sh_size / sizeof(Elf64_Rela));
 150
 151                         /* Sort the relocation information based on a symbol and
 152                          * addend key. This is a stable O(n*log n) complexity
 153                          * alogrithm but it will reduce the complexity of
 154                          * count_relocs() to linear complexity O(n)
 155                          */
 156                         sort((void *)sechdrs[i].sh_addr,
 157                              sechdrs[i].sh_size / sizeof(Elf64_Rela),
 158                              sizeof(Elf64_Rela), relacmp, relaswap);
 159
 160                         relocs += count_relocs((void *)sechdrs[i].sh_addr,
 161                                                sechdrs[i].sh_size
 162                                                / sizeof(Elf64_Rela));
 163                 }
 164         }
 165
 166 #ifdef CONFIG_DYNAMIC_FTRACE
 167         /* make the trampoline to the ftrace_caller */
 168         relocs++;
 169 #endif
 170
 171         DEBUGP("Looks like a total of %lu stubs, max\n", relocs);
 172         return relocs * sizeof(struct ppc64_stub_entry);
 173 }
 174
 175 /* Still needed for ELFv2, for .TOC. */
 176 static void dedotify_versions(struct modversion_info *vers,
 177                               unsigned long size)
 178 {
 179         struct modversion_info *end;
 180
 181         for (end = (void *)vers + size; vers < end; vers++)
 182                 if (vers->name[0] == '.')
 183                         memmove(vers->name, vers->name+1, strlen(vers->name));
 184 }
 185
 186 /* Undefined symbols which refer to .funcname, hack to funcname (or .TOC.) */
 187 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
 188 {
 189         unsigned int i;
 190
 191         for (i = 1; i < numsyms; i++) {
 192                 if (syms[i].st_shndx == SHN_UNDEF) {
 193                         char *name = strtab + syms[i].st_name;
 194                         if (name[0] == '.')
 195                                 memmove(name, name+1, strlen(name));
 196                 }
 197         }
 198 }
 199
 200 static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
 201                                const char *strtab,
 202                                unsigned int symindex)
 203 {
 204         unsigned int i, numsyms;
 205         Elf64_Sym *syms;
 206
 207         syms = (Elf64_Sym *)sechdrs[symindex].sh_addr;
 208         numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
 209
 210         for (i = 1; i < numsyms; i++) {
 211                 if (syms[i].st_shndx == SHN_UNDEF
 212                     && strcmp(strtab + syms[i].st_name, ".TOC.") == 0)
 213                         return &syms[i];
 214         }
 215         return NULL;
 216 }
 217
 218 int module_frob_arch_sections(Elf64_Ehdr *hdr,
 219                               Elf64_Shdr *sechdrs,
 220                               char *secstrings,
 221                               struct module *me)
 222 {
 223         unsigned int i;
 224
 225         /* Find .toc and .stubs sections, symtab and strtab */
 226         for (i = 1; i < hdr->e_shnum; i++) {
 227                 char *p;
 228                 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
 229                         me->arch.stubs_section = i;
 230                 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0)
 231                         me->arch.toc_section = i;
 232                 else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
 233                         dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
 234                                           sechdrs[i].sh_size);
 235
 236                 /* We don't handle .init for the moment: rename to _init */
 237                 while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
 238                         p[0] = '_';
 239
 240                 if (sechdrs[i].sh_type == SHT_SYMTAB)
 241                         dedotify((void *)hdr + sechdrs[i].sh_offset,
 242                                  sechdrs[i].sh_size / sizeof(Elf64_Sym),
 243                                  (void *)hdr
 244                                  + sechdrs[sechdrs[i].sh_link].sh_offset);
 245         }
 246
 247         if (!me->arch.stubs_section) {
 248                 printk("%s: doesn't contain .stubs.\n", me->name);
 249                 return -ENOEXEC;
 250         }
 251
 252         /* If we don't have a .toc, just use .stubs.  We need to set r2
 253            to some reasonable value in case the module calls out to
 254            other functions via a stub, or if a function pointer escapes
 255            the module by some means.  */
 256         if (!me->arch.toc_section)
 257                 me->arch.toc_section = me->arch.stubs_section;
 258
 259         /* Override the stubs size */
 260         sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
 261         return 0;
 262 }
 263
 264 /* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this
 265    gives the value maximum span in an instruction which uses a signed
 266    offset) */
 267 static inline unsigned long my_r2(Elf64_Shdr *sechdrs, struct module *me)
 268 {
 269         return sechdrs[me->arch.toc_section].sh_addr + 0x8000;
 270 }
 271
 272 /* Both low and high 16 bits are added as SIGNED additions, so if low
 273    16 bits has high bit set, high 16 bits must be adjusted.  These
 274    macros do that (stolen from binutils). */
 275 #define PPC_LO(v) ((v) & 0xffff)
 276 #define PPC_HI(v) (((v) >> 16) & 0xffff)
 277 #define PPC_HA(v) PPC_HI ((v) + 0x8000)
 278
 279 /* Patch stub to reference function and correct r2 value. */
 280 static inline int create_stub(Elf64_Shdr *sechdrs,
 281                               struct ppc64_stub_entry *entry,
 282                               struct ppc64_opd_entry *opd,
 283                               struct module *me)
 284 {
 285         long reladdr;
 286
 287         *entry = ppc64_stub;
 288
 289         /* Stub uses address relative to r2. */
 290         reladdr = (unsigned long)entry - my_r2(sechdrs, me);
 291         if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
 292                 printk("%s: Address %p of stub out of range of %p.\n",
 293                        me->name, (void *)reladdr, (void *)my_r2);
 294                 return 0;
 295         }
 296         DEBUGP("Stub %p get data from reladdr %li\n", entry, reladdr);
 297
 298         entry->jump[0] |= PPC_HA(reladdr);
 299         entry->jump[1] |= PPC_LO(reladdr);
 300         entry->opd.funcaddr = opd->funcaddr;
 301         entry->opd.r2 = opd->r2;
 302         return 1;
 303 }
 304
 305 /* Create stub to jump to function described in this OPD: we need the
 306    stub to set up the TOC ptr (r2) for the function. */
 307 static unsigned long stub_for_addr(Elf64_Shdr *sechdrs,
 308                                    unsigned long opdaddr,
 309                                    struct module *me)
 310 {
 311         struct ppc64_stub_entry *stubs;
 312         struct ppc64_opd_entry *opd = (void *)opdaddr;
 313         unsigned int i, num_stubs;
 314
 315         num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
 316
 317         /* Find this stub, or if that fails, the next avail. entry */
 318         stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
 319         for (i = 0; stubs[i].opd.funcaddr; i++) {
 320                 BUG_ON(i >= num_stubs);
 321
 322                 if (stubs[i].opd.funcaddr == opd->funcaddr)
 323                         return (unsigned long)&stubs[i];
 324         }
 325
 326         if (!create_stub(sechdrs, &stubs[i], opd, me))
 327                 return 0;
 328
 329         return (unsigned long)&stubs[i];
 330 }
 331
 332 /* We expect a noop next: if it is, replace it with instruction to
 333    restore r2. */
 334 static int restore_r2(u32 *instruction, struct module *me)
 335 {
 336         if (*instruction != PPC_INST_NOP) {
 337                 printk("%s: Expect noop after relocate, got %08x\n",
 338                        me->name, *instruction);
 339                 return 0;
 340         }
 341         *instruction = 0xe8410028;      /* ld r2,40(r1) */
 342         return 1;
 343 }
 344
 345 int apply_relocate_add(Elf64_Shdr *sechdrs,
 346                        const char *strtab,
 347                        unsigned int symindex,
 348                        unsigned int relsec,
 349                        struct module *me)
 350 {
 351         unsigned int i;
 352         Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
 353         Elf64_Sym *sym;
 354         unsigned long *location;
 355         unsigned long value;
 356
 357         DEBUGP("Applying ADD relocate section %u to %u\n", relsec,
 358                sechdrs[relsec].sh_info);
 359
 360         /* First time we're called, we can fix up .TOC. */
 361         if (!me->arch.toc_fixed) {
 362                 sym = find_dot_toc(sechdrs, strtab, symindex);
 363                 /* It's theoretically possible that a module doesn't want a
 364                  * .TOC. so don't fail it just for that. */
 365                 if (sym)
 366                         sym->st_value = my_r2(sechdrs, me);
 367                 me->arch.toc_fixed = true;
 368         }
 369
 370         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
 371                 /* This is where to make the change */
 372                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 373                         + rela[i].r_offset;
 374                 /* This is the symbol it is referring to */
 375                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
 376                         + ELF64_R_SYM(rela[i].r_info);
 377
 378                 DEBUGP("RELOC at %p: %li-type as %s (%lu) + %li\n",
 379                        location, (long)ELF64_R_TYPE(rela[i].r_info),
 380                        strtab + sym->st_name, (unsigned long)sym->st_value,
 381                        (long)rela[i].r_addend);
 382
 383                 /* `Everything is relative'. */
 384                 value = sym->st_value + rela[i].r_addend;
 385
 386                 switch (ELF64_R_TYPE(rela[i].r_info)) {
 387                 case R_PPC64_ADDR32:
 388                         /* Simply set it */
 389                         *(u32 *)location = value;
 390                         break;
 391
 392                 case R_PPC64_ADDR64:
 393                         /* Simply set it */
 394                         *(unsigned long *)location = value;
 395                         break;
 396
 397                 case R_PPC64_TOC:
 398                         *(unsigned long *)location = my_r2(sechdrs, me);
 399                         break;
 400
 401                 case R_PPC64_TOC16:
 402                         /* Subtract TOC pointer */
 403                         value -= my_r2(sechdrs, me);
 404                         if (value + 0x8000 > 0xffff) {
 405                                 printk("%s: bad TOC16 relocation (%lu)\n",
 406                                        me->name, value);
 407                                 return -ENOEXEC;
 408                         }
 409                         *((uint16_t *) location)
 410                                 = (*((uint16_t *) location) & ~0xffff)
 411                                 | (value & 0xffff);
 412                         break;
 413
 414                 case R_PPC64_TOC16_LO:
 415                         /* Subtract TOC pointer */
 416                         value -= my_r2(sechdrs, me);
 417                         *((uint16_t *) location)
 418                                 = (*((uint16_t *) location) & ~0xffff)
 419                                 | (value & 0xffff);
 420                         break;
 421
 422                 case R_PPC64_TOC16_DS:
 423                         /* Subtract TOC pointer */
 424                         value -= my_r2(sechdrs, me);
 425                         if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
 426                                 printk("%s: bad TOC16_DS relocation (%lu)\n",
 427                                        me->name, value);
 428                                 return -ENOEXEC;
 429                         }
 430                         *((uint16_t *) location)
 431                                 = (*((uint16_t *) location) & ~0xfffc)
 432                                 | (value & 0xfffc);
 433                         break;
 434
 435                 case R_PPC64_TOC16_LO_DS:
 436                         /* Subtract TOC pointer */
 437                         value -= my_r2(sechdrs, me);
 438                         if ((value & 3) != 0) {
 439                                 printk("%s: bad TOC16_LO_DS relocation (%lu)\n",
 440                                        me->name, value);
 441                                 return -ENOEXEC;
 442                         }
 443                         *((uint16_t *) location)
 444                                 = (*((uint16_t *) location) & ~0xfffc)
 445                                 | (value & 0xfffc);
 446                         break;
 447
 448                 case R_PPC64_TOC16_HA:
 449                         /* Subtract TOC pointer */
 450                         value -= my_r2(sechdrs, me);
 451                         value = ((value + 0x8000) >> 16);
 452                         *((uint16_t *) location)
 453                                 = (*((uint16_t *) location) & ~0xffff)
 454                                 | (value & 0xffff);
 455                         break;
 456
 457                 case R_PPC_REL24:
 458                         /* FIXME: Handle weak symbols here --RR */
 459                         if (sym->st_shndx == SHN_UNDEF) {
 460                                 /* External: go via stub */
 461                                 value = stub_for_addr(sechdrs, value, me);
 462                                 if (!value)
 463                                         return -ENOENT;
 464                                 if (!restore_r2((u32 *)location + 1, me))
 465                                         return -ENOEXEC;
 466                         }
 467
 468                         /* Convert value to relative */
 469                         value -= (unsigned long)location;
 470                         if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
 471                                 printk("%s: REL24 %li out of range!\n",
 472                                        me->name, (long int)value);
 473                                 return -ENOEXEC;
 474                         }
 475
 476                         /* Only replace bits 2 through 26 */
 477                         *(uint32_t *)location
 478                                 = (*(uint32_t *)location & ~0x03fffffc)
 479                                 | (value & 0x03fffffc);
 480                         break;
 481
 482                 case R_PPC64_REL64:
 483                         /* 64 bits relative (used by features fixups) */
 484                         *location = value - (unsigned long)location;
 485                         break;
 486
 487                 case R_PPC64_TOCSAVE:
 488                         /*
 489                          * Marker reloc indicates we don't have to save r2.
 490                          * That would only save us one instruction, so ignore
 491                          * it.
 492                          */
 493                         break;
 494
 495                 case R_PPC64_REL16_HA:
 496                         /* Subtract location pointer */
 497                         value -= (unsigned long)location;
 498                         value = ((value + 0x8000) >> 16);
 499                         *((uint16_t *) location)
 500                                 = (*((uint16_t *) location) & ~0xffff)
 501                                 | (value & 0xffff);
 502                         break;
 503
 504                 case R_PPC64_REL16_LO:
 505                         /* Subtract location pointer */
 506                         value -= (unsigned long)location;
 507                         *((uint16_t *) location)
 508                                 = (*((uint16_t *) location) & ~0xffff)
 509                                 | (value & 0xffff);
 510                         break;
 511
 512                 default:
 513                         printk("%s: Unknown ADD relocation: %lu\n",
 514                                me->name,
 515                                (unsigned long)ELF64_R_TYPE(rela[i].r_info));
 516                         return -ENOEXEC;
 517                 }
 518         }
 519
 520 #ifdef CONFIG_DYNAMIC_FTRACE
 521         me->arch.toc = my_r2(sechdrs, me);
 522         me->arch.tramp = stub_for_addr(sechdrs,
 523                                        (unsigned long)ftrace_caller,
 524                                        me);
 525 #endif
 526
 527         return 0;
 528 }