arch/mips/kernel/module-rela.c

   1 /*
   2  *  This program is free software; you can redistribute it and/or modify
   3  *  it under the terms of the GNU General Public License as published by
   4  *  the Free Software Foundation; either version 2 of the License, or
   5  *  (at your option) any later version.
   6  *
   7  *  This program is distributed in the hope that it will be useful,
   8  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  *  GNU General Public License for more details.
  11  *
  12  *  You should have received a copy of the GNU General Public License
  13  *  along with this program; if not, write to the Free Software
  14  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  15  *
  16  *  Copyright (C) 2001 Rusty Russell.
  17  *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
  18  *  Copyright (C) 2005 Thiemo Seufer
  19  *  Copyright (C) 2015 Imagination Technologies Ltd.
  20  */
  21
  22 #include <linux/elf.h>
  23 #include <linux/err.h>
  24 #include <linux/errno.h>
  25 #include <linux/moduleloader.h>
  26
  27 extern int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v);
  28
  29 static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)
  30 {
  31         *location = v;
  32
  33         return 0;
  34 }
  35
  36 static int apply_r_mips_26_rela(struct module *me, u32 *location, Elf_Addr v)
  37 {
  38         if (v % 4) {
  39                 pr_err("module %s: dangerous R_MIPS_26 RELA relocation\n",
  40                        me->name);
  41                 return -ENOEXEC;
  42         }
  43
  44         if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
  45                 pr_err("module %s: relocation overflow\n", me->name);
  46                 return -ENOEXEC;
  47         }
  48
  49         *location = (*location & ~0x03ffffff) | ((v >> 2) & 0x03ffffff);
  50
  51         return 0;
  52 }
  53
  54 static int apply_r_mips_hi16_rela(struct module *me, u32 *location, Elf_Addr v)
  55 {
  56         *location = (*location & 0xffff0000) |
  57                     ((((long long) v + 0x8000LL) >> 16) & 0xffff);
  58
  59         return 0;
  60 }
  61
  62 static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)
  63 {
  64         *location = (*location & 0xffff0000) | (v & 0xffff);
  65
  66         return 0;
  67 }
  68
  69 static int apply_r_mips_pc_rela(struct module *me, u32 *location, Elf_Addr v,
  70                                 unsigned bits)
  71 {
  72         unsigned long mask = GENMASK(bits - 1, 0);
  73         unsigned long se_bits;
  74         long offset;
  75
  76         if (v % 4) {
  77                 pr_err("module %s: dangerous R_MIPS_PC%u RELA relocation\n",
  78                        me->name, bits);
  79                 return -ENOEXEC;
  80         }
  81
  82         offset = ((long)v - (long)location) >> 2;
  83
  84         /* check the sign bit onwards are identical - ie. we didn't overflow */
  85         se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0;
  86         if ((offset & ~mask) != (se_bits & ~mask)) {
  87                 pr_err("module %s: relocation overflow\n", me->name);
  88                 return -ENOEXEC;
  89         }
  90
  91         *location = (*location & ~mask) | (offset & mask);
  92
  93         return 0;
  94 }
  95
  96 static int apply_r_mips_pc16_rela(struct module *me, u32 *location, Elf_Addr v)
  97 {
  98         return apply_r_mips_pc_rela(me, location, v, 16);
  99 }
 100
 101 static int apply_r_mips_pc21_rela(struct module *me, u32 *location, Elf_Addr v)
 102 {
 103         return apply_r_mips_pc_rela(me, location, v, 21);
 104 }
 105
 106 static int apply_r_mips_pc26_rela(struct module *me, u32 *location, Elf_Addr v)
 107 {
 108         return apply_r_mips_pc_rela(me, location, v, 26);
 109 }
 110
 111 static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)
 112 {
 113         *(Elf_Addr *)location = v;
 114
 115         return 0;
 116 }
 117
 118 static int apply_r_mips_higher_rela(struct module *me, u32 *location,
 119                                     Elf_Addr v)
 120 {
 121         *location = (*location & 0xffff0000) |
 122                     ((((long long) v + 0x80008000LL) >> 32) & 0xffff);
 123
 124         return 0;
 125 }
 126
 127 static int apply_r_mips_highest_rela(struct module *me, u32 *location,
 128                                      Elf_Addr v)
 129 {
 130         *location = (*location & 0xffff0000) |
 131                     ((((long long) v + 0x800080008000LL) >> 48) & 0xffff);
 132
 133         return 0;
 134 }
 135
 136 static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
 137                                 Elf_Addr v) = {
 138         [R_MIPS_NONE]           = apply_r_mips_none,
 139         [R_MIPS_32]             = apply_r_mips_32_rela,
 140         [R_MIPS_26]             = apply_r_mips_26_rela,
 141         [R_MIPS_HI16]           = apply_r_mips_hi16_rela,
 142         [R_MIPS_LO16]           = apply_r_mips_lo16_rela,
 143         [R_MIPS_PC16]           = apply_r_mips_pc16_rela,
 144         [R_MIPS_64]             = apply_r_mips_64_rela,
 145         [R_MIPS_HIGHER]         = apply_r_mips_higher_rela,
 146         [R_MIPS_HIGHEST]        = apply_r_mips_highest_rela,
 147         [R_MIPS_PC21_S2]        = apply_r_mips_pc21_rela,
 148         [R_MIPS_PC26_S2]        = apply_r_mips_pc26_rela,
 149 };
 150
 151 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 152                        unsigned int symindex, unsigned int relsec,
 153                        struct module *me)
 154 {
 155         Elf_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr;
 156         int (*handler)(struct module *me, u32 *location, Elf_Addr v);
 157         Elf_Sym *sym;
 158         u32 *location;
 159         unsigned int i, type;
 160         Elf_Addr v;
 161         int res;
 162
 163         pr_debug("Applying relocate section %u to %u\n", relsec,
 164                sechdrs[relsec].sh_info);
 165
 166         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 167                 /* This is where to make the change */
 168                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 169                         + rel[i].r_offset;
 170                 /* This is the symbol it is referring to */
 171                 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 172                         + ELF_MIPS_R_SYM(rel[i]);
 173                 if (sym->st_value >= -MAX_ERRNO) {
 174                         /* Ignore unresolved weak symbol */
 175                         if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 176                                 continue;
 177                         pr_warn("%s: Unknown symbol %s\n",
 178                                me->name, strtab + sym->st_name);
 179                         return -ENOENT;
 180                 }
 181
 182                 type = ELF_MIPS_R_TYPE(rel[i]);
 183
 184                 if (type < ARRAY_SIZE(reloc_handlers_rela))
 185                         handler = reloc_handlers_rela[type];
 186                 else
 187                         handler = NULL;
 188
 189                 if (!handler) {
 190                         pr_err("%s: Unknown relocation type %u\n",
 191                                me->name, type);
 192                         return -EINVAL;
 193                 }
 194
 195                 v = sym->st_value + rel[i].r_addend;
 196                 res = handler(me, location, v);
 197                 if (res)
 198                         return res;
 199         }
 200
 201         return 0;
 202 }