arch/alpha/kernel/module.c

   1 /*  Kernel module help for Alpha.
   2     Copyright (C) 2002 Richard Henderson.
   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/moduleloader.h>
  19 #include <linux/elf.h>
  20 #include <linux/vmalloc.h>
  21 #include <linux/fs.h>
  22 #include <linux/string.h>
  23 #include <linux/kernel.h>
  24 #include <linux/slab.h>
  25
  26 #if 0
  27 #define DEBUGP printk
  28 #else
  29 #define DEBUGP(fmt...)
  30 #endif
  31
  32 void *
  33 module_alloc(unsigned long size)
  34 {
  35         if (size == 0)
  36                 return NULL;
  37         return vmalloc(size);
  38 }
  39
  40 void
  41 module_free(struct module *mod, void *module_region)
  42 {
  43         vfree(module_region);
  44 }
  45
  46 /* Allocate the GOT at the end of the core sections.  */
  47
  48 struct got_entry {
  49         struct got_entry *next;
  50         Elf64_Sxword r_addend;
  51         int got_offset;
  52 };
  53
  54 static inline void
  55 process_reloc_for_got(Elf64_Rela *rela,
  56                       struct got_entry *chains, Elf64_Xword *poffset)
  57 {
  58         unsigned long r_sym = ELF64_R_SYM (rela->r_info);
  59         unsigned long r_type = ELF64_R_TYPE (rela->r_info);
  60         Elf64_Sxword r_addend = rela->r_addend;
  61         struct got_entry *g;
  62
  63         if (r_type != R_ALPHA_LITERAL)
  64                 return;
  65
  66         for (g = chains + r_sym; g ; g = g->next)
  67                 if (g->r_addend == r_addend) {
  68                         if (g->got_offset == 0) {
  69                                 g->got_offset = *poffset;
  70                                 *poffset += 8;
  71                         }
  72                         goto found_entry;
  73                 }
  74
  75         g = kmalloc (sizeof (*g), GFP_KERNEL);
  76         g->next = chains[r_sym].next;
  77         g->r_addend = r_addend;
  78         g->got_offset = *poffset;
  79         *poffset += 8;
  80         chains[r_sym].next = g;
  81
  82  found_entry:
  83         /* Trick: most of the ELF64_R_TYPE field is unused.  There are
  84            42 valid relocation types, and a 32-bit field.  Co-opt the
  85            bits above 256 to store the got offset for this reloc.  */
  86         rela->r_info |= g->got_offset << 8;
  87 }
  88
  89 int
  90 module_frob_arch_sections(Elf64_Ehdr *hdr, Elf64_Shdr *sechdrs,
  91                           char *secstrings, struct module *me)
  92 {
  93         struct got_entry *chains;
  94         Elf64_Rela *rela;
  95         Elf64_Shdr *esechdrs, *symtab, *s, *got;
  96         unsigned long nsyms, nrela, i;
  97
  98         esechdrs = sechdrs + hdr->e_shnum;
  99         symtab = got = NULL;
 100
 101         /* Find out how large the symbol table is.  Allocate one got_entry
 102            head per symbol.  Normally this will be enough, but not always.
 103            We'll chain different offsets for the symbol down each head.  */
 104         for (s = sechdrs; s < esechdrs; ++s)
 105                 if (s->sh_type == SHT_SYMTAB)
 106                         symtab = s;
 107                 else if (!strcmp(".got", secstrings + s->sh_name)) {
 108                         got = s;
 109                         me->arch.gotsecindex = s - sechdrs;
 110                 }
 111
 112         if (!symtab) {
 113                 printk(KERN_ERR "module %s: no symbol table\n", me->name);
 114                 return -ENOEXEC;
 115         }
 116         if (!got) {
 117                 printk(KERN_ERR "module %s: no got section\n", me->name);
 118                 return -ENOEXEC;
 119         }
 120
 121         nsyms = symtab->sh_size / sizeof(Elf64_Sym);
 122         chains = kcalloc(nsyms, sizeof(struct got_entry), GFP_KERNEL);
 123         if (!chains) {
 124                 printk(KERN_ERR
 125                        "module %s: no memory for symbol chain buffer\n",
 126                        me->name);
 127                 return -ENOMEM;
 128         }
 129
 130         got->sh_size = 0;
 131         got->sh_addralign = 8;
 132         got->sh_type = SHT_NOBITS;
 133
 134         /* Examine all LITERAL relocations to find out what GOT entries
 135            are required.  This sizes the GOT section as well.  */
 136         for (s = sechdrs; s < esechdrs; ++s)
 137                 if (s->sh_type == SHT_RELA) {
 138                         nrela = s->sh_size / sizeof(Elf64_Rela);
 139                         rela = (void *)hdr + s->sh_offset;
 140                         for (i = 0; i < nrela; ++i)
 141                                 process_reloc_for_got(rela+i, chains,
 142                                                       &got->sh_size);
 143                 }
 144
 145         /* Free the memory we allocated.  */
 146         for (i = 0; i < nsyms; ++i) {
 147                 struct got_entry *g, *n;
 148                 for (g = chains[i].next; g ; g = n) {
 149                         n = g->next;
 150                         kfree(g);
 151                 }
 152         }
 153         kfree(chains);
 154
 155         return 0;
 156 }
 157
 158 int
 159 apply_relocate(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex,
 160                unsigned int relsec, struct module *me)
 161 {
 162         printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name);
 163         return -ENOEXEC;
 164 }
 165
 166 int
 167 apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab,
 168                    unsigned int symindex, unsigned int relsec,
 169                    struct module *me)
 170 {
 171         Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
 172         unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela);
 173         Elf64_Sym *symtab, *sym;
 174         void *base, *location;
 175         unsigned long got, gp;
 176
 177         DEBUGP("Applying relocate section %u to %u\n", relsec,
 178                sechdrs[relsec].sh_info);
 179
 180         base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr;
 181         symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr;
 182
 183         /* The small sections were sorted to the end of the segment.
 184            The following should definitely cover them.  */
 185         gp = (u64)me->module_core + me->core_size - 0x8000;
 186         got = sechdrs[me->arch.gotsecindex].sh_addr;
 187
 188         for (i = 0; i < n; i++) {
 189                 unsigned long r_sym = ELF64_R_SYM (rela[i].r_info);
 190                 unsigned long r_type = ELF64_R_TYPE (rela[i].r_info);
 191                 unsigned long r_got_offset = r_type >> 8;
 192                 unsigned long value, hi, lo;
 193                 r_type &= 0xff;
 194
 195                 /* This is where to make the change.  */
 196                 location = base + rela[i].r_offset;
 197
 198                 /* This is the symbol it is referring to.  Note that all
 199                    unresolved symbols have been resolved.  */
 200                 sym = symtab + r_sym;
 201                 value = sym->st_value + rela[i].r_addend;
 202
 203                 switch (r_type) {
 204                 case R_ALPHA_NONE:
 205                         break;
 206                 case R_ALPHA_REFQUAD:
 207                         /* BUG() can produce misaligned relocations. */
 208                         ((u32 *)location)[0] = value;
 209                         ((u32 *)location)[1] = value >> 32;
 210                         break;
 211                 case R_ALPHA_GPREL32:
 212                         value -= gp;
 213                         if ((int)value != value)
 214                                 goto reloc_overflow;
 215                         *(u32 *)location = value;
 216                         break;
 217                 case R_ALPHA_LITERAL:
 218                         hi = got + r_got_offset;
 219                         lo = hi - gp;
 220                         if ((short)lo != lo)
 221                                 goto reloc_overflow;
 222                         *(u16 *)location = lo;
 223                         *(u64 *)hi = value;
 224                         break;
 225                 case R_ALPHA_LITUSE:
 226                         break;
 227                 case R_ALPHA_GPDISP:
 228                         value = gp - (u64)location;
 229                         lo = (short)value;
 230                         hi = (int)(value - lo);
 231                         if (hi + lo != value)
 232                                 goto reloc_overflow;
 233                         *(u16 *)location = hi >> 16;
 234                         *(u16 *)(location + rela[i].r_addend) = lo;
 235                         break;
 236                 case R_ALPHA_BRSGP:
 237                         /* BRSGP is only allowed to bind to local symbols.
 238                            If the section is undef, this means that the
 239                            value was resolved from somewhere else.  */
 240                         if (sym->st_shndx == SHN_UNDEF)
 241                                 goto reloc_overflow;
 242                         if ((sym->st_other & STO_ALPHA_STD_GPLOAD) ==
 243                             STO_ALPHA_STD_GPLOAD)
 244                                 /* Omit the prologue. */
 245                                 value += 8;
 246                         /* FALLTHRU */
 247                 case R_ALPHA_BRADDR:
 248                         value -= (u64)location + 4;
 249                         if (value & 3)
 250                                 goto reloc_overflow;
 251                         value = (long)value >> 2;
 252                         if (value + (1<<21) >= 1<<22)
 253                                 goto reloc_overflow;
 254                         value &= 0x1fffff;
 255                         value |= *(u32 *)location & ~0x1fffff;
 256                         *(u32 *)location = value;
 257                         break;
 258                 case R_ALPHA_HINT:
 259                         break;
 260                 case R_ALPHA_SREL32:
 261                         value -= (u64)location;
 262                         if ((int)value != value)
 263                                 goto reloc_overflow;
 264                         *(u32 *)location = value;
 265                         break;
 266                 case R_ALPHA_SREL64:
 267                         value -= (u64)location;
 268                         *(u64 *)location = value;
 269                         break;
 270                 case R_ALPHA_GPRELHIGH:
 271                         value = (long)(value - gp + 0x8000) >> 16;
 272                         if ((short) value != value)
 273                                 goto reloc_overflow;
 274                         *(u16 *)location = value;
 275                         break;
 276                 case R_ALPHA_GPRELLOW:
 277                         value -= gp;
 278                         *(u16 *)location = value;
 279                         break;
 280                 case R_ALPHA_GPREL16:
 281                         value -= gp;
 282                         if ((short) value != value)
 283                                 goto reloc_overflow;
 284                         *(u16 *)location = value;
 285                         break;
 286                 default:
 287                         printk(KERN_ERR "module %s: Unknown relocation: %lu\n",
 288                                me->name, r_type);
 289                         return -ENOEXEC;
 290                 reloc_overflow:
 291                         if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION)
 292                           printk(KERN_ERR
 293                                  "module %s: Relocation (type %lu) overflow vs section %d\n",
 294                                  me->name, r_type, sym->st_shndx);
 295                         else
 296                           printk(KERN_ERR
 297                                  "module %s: Relocation (type %lu) overflow vs %s\n",
 298                                  me->name, r_type, strtab + sym->st_name);
 299                         return -ENOEXEC;
 300                 }
 301         }
 302
 303         return 0;
 304 }
 305
 306 int
 307 module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
 308                 struct module *me)
 309 {
 310         return 0;
 311 }
 312
 313 void
 314 module_arch_cleanup(struct module *mod)
 315 {
 316 }