arch/v850/kernel/module.c

   1 /*
   2  * arch/v850/kernel/module.c -- Architecture-specific module functions
   3  *
   4  *  Copyright (C) 2002,03  NEC Electronics Corporation
   5  *  Copyright (C) 2002,03  Miles Bader <miles@gnu.org>
   6  *  Copyright (C) 2001,03  Rusty Russell
   7  *
   8  * This file is subject to the terms and conditions of the GNU General
   9  * Public License.  See the file COPYING in the main directory of this
  10  * archive for more details.
  11  *
  12  * Written by Miles Bader <miles@gnu.org>
  13  *
  14  * Derived in part from arch/ppc/kernel/module.c
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/moduleloader.h>
  20 #include <linux/elf.h>
  21
  22 #if 0
  23 #define DEBUGP printk
  24 #else
  25 #define DEBUGP(fmt , ...)
  26 #endif
  27
  28 void *module_alloc (unsigned long size)
  29 {
  30         return size == 0 ? 0 : vmalloc (size);
  31 }
  32
  33 void module_free (struct module *mod, void *module_region)
  34 {
  35         vfree (module_region);
  36         /* FIXME: If module_region == mod->init_region, trim exception
  37            table entries. */
  38 }
  39
  40 int module_finalize (const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
  41                      struct module *mod)
  42 {
  43         return 0;
  44 }
  45
  46 /* Count how many different relocations (different symbol, different
  47    addend) */
  48 static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
  49 {
  50         unsigned int i, j, ret = 0;
  51
  52         /* Sure, this is order(n^2), but it's usually short, and not
  53            time critical */
  54         for (i = 0; i < num; i++) {
  55                 for (j = 0; j < i; j++) {
  56                         /* If this addend appeared before, it's
  57                            already been counted */
  58                         if (ELF32_R_SYM(rela[i].r_info)
  59                             == ELF32_R_SYM(rela[j].r_info)
  60                             && rela[i].r_addend == rela[j].r_addend)
  61                                 break;
  62                 }
  63                 if (j == i) ret++;
  64         }
  65         return ret;
  66 }
  67
  68 /* Get the potential trampolines size required of the init and
  69    non-init sections */
  70 static unsigned long get_plt_size(const Elf32_Ehdr *hdr,
  71                                   const Elf32_Shdr *sechdrs,
  72                                   const char *secstrings,
  73                                   int is_init)
  74 {
  75         unsigned long ret = 0;
  76         unsigned i;
  77
  78         /* Everything marked ALLOC (this includes the exported
  79            symbols) */
  80         for (i = 1; i < hdr->e_shnum; i++) {
  81                 /* If it's called *.init*, and we're not init, we're
  82                    not interested */
  83                 if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0)
  84                     != is_init)
  85                         continue;
  86
  87                 if (sechdrs[i].sh_type == SHT_RELA) {
  88                         DEBUGP("Found relocations in section %u\n", i);
  89                         DEBUGP("Ptr: %p.  Number: %u\n",
  90                                (void *)hdr + sechdrs[i].sh_offset,
  91                                sechdrs[i].sh_size / sizeof(Elf32_Rela));
  92                         ret += count_relocs((void *)hdr
  93                                              + sechdrs[i].sh_offset,
  94                                              sechdrs[i].sh_size
  95                                              / sizeof(Elf32_Rela))
  96                                 * sizeof(struct v850_plt_entry);
  97                 }
  98         }
  99
 100         return ret;
 101 }
 102
 103 int module_frob_arch_sections(Elf32_Ehdr *hdr,
 104                               Elf32_Shdr *sechdrs,
 105                               char *secstrings,
 106                               struct module *me)
 107 {
 108         unsigned int i;
 109
 110         /* Find .plt and .pltinit sections */
 111         for (i = 0; i < hdr->e_shnum; i++) {
 112                 if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0)
 113                         me->arch.init_plt_section = i;
 114                 else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
 115                         me->arch.core_plt_section = i;
 116         }
 117         if (!me->arch.core_plt_section || !me->arch.init_plt_section) {
 118                 printk("Module doesn't contain .plt or .plt.init sections.\n");
 119                 return -ENOEXEC;
 120         }
 121
 122         /* Override their sizes */
 123         sechdrs[me->arch.core_plt_section].sh_size
 124                 = get_plt_size(hdr, sechdrs, secstrings, 0);
 125         sechdrs[me->arch.init_plt_section].sh_size
 126                 = get_plt_size(hdr, sechdrs, secstrings, 1);
 127         return 0;
 128 }
 129
 130 int apply_relocate (Elf32_Shdr *sechdrs, const char *strtab,
 131                     unsigned int symindex, unsigned int relsec,
 132                     struct module *mod)
 133 {
 134         printk ("Barf\n");
 135         return -ENOEXEC;
 136 }
 137
 138 /* Set up a trampoline in the PLT to bounce us to the distant function */
 139 static uint32_t do_plt_call (void *location, Elf32_Addr val,
 140                              Elf32_Shdr *sechdrs, struct module *mod)
 141 {
 142         struct v850_plt_entry *entry;
 143         /* Instructions used to do the indirect jump.  */
 144         uint32_t tramp[2];
 145
 146         /* We have to trash a register, so we assume that any control
 147            transfer more than 21-bits away must be a function call
 148            (so we can use a call-clobbered register).  */
 149         tramp[0] = 0x0621 + ((val & 0xffff) << 16);   /* mov sym, r1 ... */
 150         tramp[1] = ((val >> 16) & 0xffff) + 0x610000; /* ...; jmp r1 */
 151
 152         /* Init, or core PLT? */
 153         if (location >= mod->module_core
 154             && location < mod->module_core + mod->core_size)
 155                 entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr;
 156         else
 157                 entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr;
 158
 159         /* Find this entry, or if that fails, the next avail. entry */
 160         while (entry->tramp[0])
 161                 if (entry->tramp[0] == tramp[0] && entry->tramp[1] == tramp[1])
 162                         return (uint32_t)entry;
 163                 else
 164                         entry++;
 165
 166         entry->tramp[0] = tramp[0];
 167         entry->tramp[1] = tramp[1];
 168
 169         return (uint32_t)entry;
 170 }
 171
 172 int apply_relocate_add (Elf32_Shdr *sechdrs, const char *strtab,
 173                         unsigned int symindex, unsigned int relsec,
 174                         struct module *mod)
 175 {
 176         unsigned int i;
 177         Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
 178
 179         DEBUGP ("Applying relocate section %u to %u\n", relsec,
 180                 sechdrs[relsec].sh_info);
 181
 182         for (i = 0; i < sechdrs[relsec].sh_size / sizeof (*rela); i++) {
 183                 /* This is where to make the change */
 184                 uint32_t *loc
 185                         = ((void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 186                            + rela[i].r_offset);
 187                 /* This is the symbol it is referring to.  Note that all
 188                    undefined symbols have been resolved.  */
 189                 Elf32_Sym *sym
 190                         = ((Elf32_Sym *)sechdrs[symindex].sh_addr
 191                            + ELF32_R_SYM (rela[i].r_info));
 192                 uint32_t val = sym->st_value + rela[i].r_addend;
 193
 194                 switch (ELF32_R_TYPE (rela[i].r_info)) {
 195                 case R_V850_32:
 196                         /* We write two shorts instead of a long because even
 197                            32-bit insns only need half-word alignment, but
 198                            32-bit data writes need to be long-word aligned.  */
 199                         val += ((uint16_t *)loc)[0];
 200                         val += ((uint16_t *)loc)[1] << 16;
 201                         ((uint16_t *)loc)[0] = val & 0xffff;
 202                         ((uint16_t *)loc)[1] = (val >> 16) & 0xffff;
 203                         break;
 204
 205                 case R_V850_22_PCREL:
 206                         /* Maybe jump indirectly via a PLT table entry.  */
 207                         if ((int32_t)(val - (uint32_t)loc) > 0x1fffff
 208                             || (int32_t)(val - (uint32_t)loc) < -0x200000)
 209                                 val = do_plt_call (loc, val, sechdrs, mod);
 210
 211                         val -= (uint32_t)loc;
 212
 213                         /* We write two shorts instead of a long because
 214                            even 32-bit insns only need half-word alignment,
 215                            but 32-bit data writes need to be long-word
 216                            aligned.  */
 217                         ((uint16_t *)loc)[0] =
 218                                 (*(uint16_t *)loc & 0xffc0) /* opcode + reg */
 219                                 | ((val >> 16) & 0xffc03f); /* offs high */
 220                         ((uint16_t *)loc)[1] =
 221                                 (val & 0xffff);             /* offs low */
 222                         break;
 223
 224                 default:
 225                         printk (KERN_ERR "module %s: Unknown reloc: %u\n",
 226                                 mod->name, ELF32_R_TYPE (rela[i].r_info));
 227                         return -ENOEXEC;
 228                 }
 229         }
 230
 231         return 0;
 232 }
 233
 234 void
 235 module_arch_cleanup(struct module *mod)
 236 {
 237 }