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 = kmalloc(nsyms * sizeof(struct got_entry), GFP_KERNEL);
 123         memset(chains, 0, nsyms * sizeof(struct got_entry));
 124
 125         got->sh_size = 0;
 126         got->sh_addralign = 8;
 127         got->sh_type = SHT_NOBITS;
 128
 129         /* Examine all LITERAL relocations to find out what GOT entries
 130            are required.  This sizes the GOT section as well.  */
 131         for (s = sechdrs; s < esechdrs; ++s)
 132                 if (s->sh_type == SHT_RELA) {
 133                         nrela = s->sh_size / sizeof(Elf64_Rela);
 134                         rela = (void *)hdr + s->sh_offset;
 135                         for (i = 0; i < nrela; ++i)
 136                                 process_reloc_for_got(rela+i, chains,
 137                                                       &got->sh_size);
 138                 }
 139
 140         /* Free the memory we allocated.  */
 141         for (i = 0; i < nsyms; ++i) {
 142                 struct got_entry *g, *n;
 143                 for (g = chains[i].next; g ; g = n) {
 144                         n = g->next;
 145                         kfree(g);
 146                 }
 147         }
 148         kfree(chains);
 149
 150         return 0;
 151 }
 152
 153 int
 154 apply_relocate(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex,
 155                unsigned int relsec, struct module *me)
 156 {
 157         printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name);
 158         return -ENOEXEC;
 159 }
 160
 161 int
 162 apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab,
 163                    unsigned int symindex, unsigned int relsec,
 164                    struct module *me)
 165 {
 166         Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
 167         unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela);
 168         Elf64_Sym *symtab, *sym;
 169         void *base, *location;
 170         unsigned long got, gp;
 171
 172         DEBUGP("Applying relocate section %u to %u\n", relsec,
 173                sechdrs[relsec].sh_info);
 174
 175         base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr;
 176         symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr;
 177
 178         /* The small sections were sorted to the end of the segment.
 179            The following should definitely cover them.  */
 180         gp = (u64)me->module_core + me->core_size - 0x8000;
 181         got = sechdrs[me->arch.gotsecindex].sh_addr;
 182
 183         for (i = 0; i < n; i++) {
 184                 unsigned long r_sym = ELF64_R_SYM (rela[i].r_info);
 185                 unsigned long r_type = ELF64_R_TYPE (rela[i].r_info);
 186                 unsigned long r_got_offset = r_type >> 8;
 187                 unsigned long value, hi, lo;
 188                 r_type &= 0xff;
 189
 190                 /* This is where to make the change.  */
 191                 location = base + rela[i].r_offset;
 192
 193                 /* This is the symbol it is referring to.  Note that all
 194                    unresolved symbols have been resolved.  */
 195                 sym = symtab + r_sym;
 196                 value = sym->st_value + rela[i].r_addend;
 197
 198                 switch (r_type) {
 199                 case R_ALPHA_NONE:
 200                         break;
 201                 case R_ALPHA_REFQUAD:
 202                         /* BUG() can produce misaligned relocations. */
 203                         ((u32 *)location)[0] = value;
 204                         ((u32 *)location)[1] = value >> 32;
 205                         break;
 206                 case R_ALPHA_GPREL32:
 207                         value -= gp;
 208                         if ((int)value != value)
 209                                 goto reloc_overflow;
 210                         *(u32 *)location = value;
 211                         break;
 212                 case R_ALPHA_LITERAL:
 213                         hi = got + r_got_offset;
 214                         lo = hi - gp;
 215                         if ((short)lo != lo)
 216                                 goto reloc_overflow;
 217                         *(u16 *)location = lo;
 218                         *(u64 *)hi = value;
 219                         break;
 220                 case R_ALPHA_LITUSE:
 221                         break;
 222                 case R_ALPHA_GPDISP:
 223                         value = gp - (u64)location;
 224                         lo = (short)value;
 225                         hi = (int)(value - lo);
 226                         if (hi + lo != value)
 227                                 goto reloc_overflow;
 228                         *(u16 *)location = hi >> 16;
 229                         *(u16 *)(location + rela[i].r_addend) = lo;
 230                         break;
 231                 case R_ALPHA_BRSGP:
 232                         /* BRSGP is only allowed to bind to local symbols.
 233                            If the section is undef, this means that the
 234                            value was resolved from somewhere else.  */
 235                         if (sym->st_shndx == SHN_UNDEF)
 236                                 goto reloc_overflow;
 237                         if ((sym->st_other & STO_ALPHA_STD_GPLOAD) ==
 238                             STO_ALPHA_STD_GPLOAD)
 239                                 /* Omit the prologue. */
 240                                 value += 8;
 241                         /* FALLTHRU */
 242                 case R_ALPHA_BRADDR:
 243                         value -= (u64)location + 4;
 244                         if (value & 3)
 245                                 goto reloc_overflow;
 246                         value = (long)value >> 2;
 247                         if (value + (1<<21) >= 1<<22)
 248                                 goto reloc_overflow;
 249                         value &= 0x1fffff;
 250                         value |= *(u32 *)location & ~0x1fffff;
 251                         *(u32 *)location = value;
 252                         break;
 253                 case R_ALPHA_HINT:
 254                         break;
 255                 case R_ALPHA_SREL32:
 256                         value -= (u64)location;
 257                         if ((int)value != value)
 258                                 goto reloc_overflow;
 259                         *(u32 *)location = value;
 260                         break;
 261                 case R_ALPHA_SREL64:
 262                         value -= (u64)location;
 263                         *(u64 *)location = value;
 264                         break;
 265                 case R_ALPHA_GPRELHIGH:
 266                         value = (long)(value - gp + 0x8000) >> 16;
 267                         if ((short) value != value)
 268                                 goto reloc_overflow;
 269                         *(u16 *)location = value;
 270                         break;
 271                 case R_ALPHA_GPRELLOW:
 272                         value -= gp;
 273                         *(u16 *)location = value;
 274                         break;
 275                 case R_ALPHA_GPREL16:
 276                         value -= gp;
 277                         if ((short) value != value)
 278                                 goto reloc_overflow;
 279                         *(u16 *)location = value;
 280                         break;
 281                 default:
 282                         printk(KERN_ERR "module %s: Unknown relocation: %lu\n",
 283                                me->name, r_type);
 284                         return -ENOEXEC;
 285                 reloc_overflow:
 286                         if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION)
 287                           printk(KERN_ERR
 288                                  "module %s: Relocation (type %lu) overflow vs section %d\n",
 289                                  me->name, r_type, sym->st_shndx);
 290                         else
 291                           printk(KERN_ERR
 292                                  "module %s: Relocation (type %lu) overflow vs %s\n",
 293                                  me->name, r_type, strtab + sym->st_name);
 294                         return -ENOEXEC;
 295                 }
 296         }
 297
 298         return 0;
 299 }
 300
 301 int
 302 module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
 303                 struct module *me)
 304 {
 305         return 0;
 306 }
 307
 308 void
 309 module_arch_cleanup(struct module *mod)
 310 {
 311 }