arch/x86_64/kernel/module.c

   1 /*  Kernel module help for x86-64
   2     Copyright (C) 2001 Rusty Russell.
   3     Copyright (C) 2002,2003 Andi Kleen, SuSE Labs.
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program; if not, write to the Free Software
  17     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 */
  19 #include <linux/moduleloader.h>
  20 #include <linux/elf.h>
  21 #include <linux/vmalloc.h>
  22 #include <linux/fs.h>
  23 #include <linux/string.h>
  24 #include <linux/kernel.h>
  25 #include <linux/slab.h>
  26 #include <linux/vmalloc.h>
  27
  28 #include <asm/system.h>
  29 #include <asm/page.h>
  30 #include <asm/pgtable.h>
  31
  32 #define DEBUGP(fmt...)
  33
  34 static struct vm_struct *mod_vmlist;
  35
  36 void module_free(struct module *mod, void *module_region)
  37 {
  38         struct vm_struct **prevp, *map;
  39         int i;
  40         unsigned long addr = (unsigned long)module_region;
  41
  42         if (!addr)
  43                 return;
  44         write_lock(&vmlist_lock);
  45         for (prevp = &mod_vmlist ; (map = *prevp) ; prevp = &map->next) {
  46                 if ((unsigned long)map->addr == addr) {
  47                         *prevp = map->next;
  48                         goto found;
  49                 }
  50         }
  51         write_unlock(&vmlist_lock);
  52         printk("Trying to unmap nonexistent module vm area (%lx)\n", addr);
  53         return;
  54  found:
  55         unmap_vm_area(map);
  56         write_unlock(&vmlist_lock);
  57         if (map->pages) {
  58                 for (i = 0; i < map->nr_pages; i++)
  59                         if (map->pages[i])
  60                                 __free_page(map->pages[i]);
  61                 kfree(map->pages);
  62         }
  63         kfree(map);
  64 }
  65
  66 void *module_alloc(unsigned long size)
  67 {
  68         struct vm_struct **p, *tmp, *area;
  69         struct page **pages;
  70         void *addr;
  71         unsigned int nr_pages, array_size, i;
  72
  73         if (!size)
  74                 return NULL;
  75         size = PAGE_ALIGN(size);
  76         if (size > MODULES_LEN)
  77                 return NULL;
  78
  79         area = (struct vm_struct *) kmalloc(sizeof(*area), GFP_KERNEL);
  80         if (!area)
  81                 return NULL;
  82         memset(area, 0, sizeof(struct vm_struct));
  83
  84         write_lock(&vmlist_lock);
  85         addr = (void *) MODULES_VADDR;
  86         for (p = &mod_vmlist; (tmp = *p); p = &tmp->next) {
  87                 void *next;
  88                 DEBUGP("vmlist %p %lu addr %p\n", tmp->addr, tmp->size, addr);
  89                 if (size + (unsigned long) addr + PAGE_SIZE < (unsigned long) tmp->addr)
  90                         break;
  91                 next = (void *) (tmp->size + (unsigned long) tmp->addr);
  92                 if (next > addr)
  93                         addr = next;
  94         }
  95
  96         if ((unsigned long)addr + size >= MODULES_END) {
  97                 write_unlock(&vmlist_lock);
  98                 kfree(area);
  99                 return NULL;
 100         }
 101         DEBUGP("addr %p\n", addr);
 102
 103         area->next = *p;
 104         *p = area;
 105         area->size = size + PAGE_SIZE;
 106         area->addr = addr;
 107         write_unlock(&vmlist_lock);
 108
 109         nr_pages = size >> PAGE_SHIFT;
 110         array_size = (nr_pages * sizeof(struct page *));
 111
 112         area->nr_pages = nr_pages;
 113         area->pages = pages = kmalloc(array_size, GFP_KERNEL);
 114         if (!area->pages)
 115                 goto fail;
 116
 117         memset(area->pages, 0, array_size);
 118         for (i = 0; i < nr_pages; i++) {
 119                 area->pages[i] = alloc_page(GFP_KERNEL);
 120                 if (area->pages[i] == NULL)
 121                         goto fail;
 122         }
 123
 124         if (map_vm_area(area, PAGE_KERNEL_EXEC, &pages))
 125                 goto fail;
 126
 127         memset(addr, 0, size);
 128         DEBUGP("module_alloc size %lu = %p\n", size, addr);
 129         return addr;
 130
 131 fail:
 132         module_free(NULL, addr);
 133         return NULL;
 134 }
 135
 136 /* We don't need anything special. */
 137 int module_frob_arch_sections(Elf_Ehdr *hdr,
 138                               Elf_Shdr *sechdrs,
 139                               char *secstrings,
 140                               struct module *mod)
 141 {
 142         return 0;
 143 }
 144
 145 int apply_relocate_add(Elf64_Shdr *sechdrs,
 146                    const char *strtab,
 147                    unsigned int symindex,
 148                    unsigned int relsec,
 149                    struct module *me)
 150 {
 151         unsigned int i;
 152         Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
 153         Elf64_Sym *sym;
 154         void *loc;
 155         u64 val;
 156
 157         DEBUGP("Applying relocate section %u to %u\n", relsec,
 158                sechdrs[relsec].sh_info);
 159         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 160                 /* This is where to make the change */
 161                 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 162                         + rel[i].r_offset;
 163
 164                 /* This is the symbol it is referring to.  Note that all
 165                    undefined symbols have been resolved.  */
 166                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
 167                         + ELF64_R_SYM(rel[i].r_info);
 168
 169                 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
 170                        (int)ELF64_R_TYPE(rel[i].r_info),
 171                        sym->st_value, rel[i].r_addend, (u64)loc);
 172
 173                 val = sym->st_value + rel[i].r_addend;
 174
 175                 switch (ELF64_R_TYPE(rel[i].r_info)) {
 176                 case R_X86_64_NONE:
 177                         break;
 178                 case R_X86_64_64:
 179                         *(u64 *)loc = val;
 180                         break;
 181                 case R_X86_64_32:
 182                         *(u32 *)loc = val;
 183                         if (val != *(u32 *)loc)
 184                                 goto overflow;
 185                         break;
 186                 case R_X86_64_32S:
 187                         *(s32 *)loc = val;
 188                         if ((s64)val != *(s32 *)loc)
 189                                 goto overflow;
 190                         break;
 191                 case R_X86_64_PC32:
 192                         val -= (u64)loc;
 193                         *(u32 *)loc = val;
 194 #if 0
 195                         if ((s64)val != *(s32 *)loc)
 196                                 goto overflow;
 197 #endif
 198                         break;
 199                 default:
 200                         printk(KERN_ERR "module %s: Unknown rela relocation: %Lu\n",
 201                                me->name, ELF64_R_TYPE(rel[i].r_info));
 202                         return -ENOEXEC;
 203                 }
 204         }
 205         return 0;
 206
 207 overflow:
 208         printk(KERN_ERR "overflow in relocation type %d val %Lx\n",
 209                (int)ELF64_R_TYPE(rel[i].r_info), val);
 210         printk(KERN_ERR "`%s' likely not compiled with -mcmodel=kernel\n",
 211                me->name);
 212         return -ENOEXEC;
 213 }
 214
 215 int apply_relocate(Elf_Shdr *sechdrs,
 216                    const char *strtab,
 217                    unsigned int symindex,
 218                    unsigned int relsec,
 219                    struct module *me)
 220 {
 221         printk("non add relocation not supported\n");
 222         return -ENOSYS;
 223 }
 224
 225 extern void apply_alternatives(void *start, void *end);
 226
 227 int module_finalize(const Elf_Ehdr *hdr,
 228                     const Elf_Shdr *sechdrs,
 229                     struct module *me)
 230 {
 231         const Elf_Shdr *s;
 232         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 233
 234         /* look for .altinstructions to patch */
 235         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 236                 void *seg;
 237                 if (strcmp(".altinstructions", secstrings + s->sh_name))
 238                         continue;
 239                 seg = (void *)s->sh_addr;
 240                 apply_alternatives(seg, seg + s->sh_size);
 241         }
 242         return 0;
 243 }
 244
 245 void module_arch_cleanup(struct module *mod)
 246 {
 247 }