arch/hexagon/kernel/module.c

   1 /*
   2  * Kernel module loader for Hexagon
   3  *
   4  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 and
   8  * only version 2 as published by the Free Software Foundation.
   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., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA.
  19  */
  20
  21 #include <asm/module.h>
  22 #include <linux/elf.h>
  23 #include <linux/module.h>
  24 #include <linux/moduleloader.h>
  25 #include <linux/vmalloc.h>
  26
  27 #if 0
  28 #define DEBUGP printk
  29 #else
  30 #define DEBUGP(fmt , ...)
  31 #endif
  32
  33 /*
  34  * module_frob_arch_sections - tweak got/plt sections.
  35  * @hdr - pointer to elf header
  36  * @sechdrs - pointer to elf load section headers
  37  * @secstrings - symbol names
  38  * @mod - pointer to module
  39  */
  40 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
  41                                 char *secstrings,
  42                                 struct module *mod)
  43 {
  44         unsigned int i;
  45         int found = 0;
  46
  47         /* Look for .plt and/or .got.plt and/or .init.plt sections */
  48         for (i = 0; i < hdr->e_shnum; i++) {
  49                 DEBUGP("Section %d is %s\n", i,
  50                        secstrings + sechdrs[i].sh_name);
  51                 if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
  52                         found = i+1;
  53                 if (strcmp(secstrings + sechdrs[i].sh_name, ".got.plt") == 0)
  54                         found = i+1;
  55                 if (strcmp(secstrings + sechdrs[i].sh_name, ".rela.plt") == 0)
  56                         found = i+1;
  57         }
  58
  59         /* At this time, we don't support modules comiled with -shared */
  60         if (found) {
  61                 printk(KERN_WARNING
  62                         "Module '%s' contains unexpected .plt/.got sections.\n",
  63                         mod->name);
  64                 /*  return -ENOEXEC;  */
  65         }
  66
  67         return 0;
  68 }
  69
  70 /*
  71  * apply_relocate_add - perform rela relocations.
  72  * @sechdrs - pointer to section headers
  73  * @strtab - some sort of start address?
  74  * @symindex - symbol index offset or something?
  75  * @relsec - address to relocate to?
  76  * @module - pointer to module
  77  *
  78  * Perform rela relocations.
  79  */
  80 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
  81                         unsigned int symindex, unsigned int relsec,
  82                         struct module *module)
  83 {
  84         unsigned int i;
  85         Elf32_Sym *sym;
  86         uint32_t *location;
  87         uint32_t value;
  88         unsigned int nrelocs = sechdrs[relsec].sh_size / sizeof(Elf32_Rela);
  89         Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
  90         Elf32_Word sym_info = sechdrs[relsec].sh_info;
  91         Elf32_Sym *sym_base = (Elf32_Sym *) sechdrs[symindex].sh_addr;
  92         void *loc_base = (void *) sechdrs[sym_info].sh_addr;
  93
  94         DEBUGP("Applying relocations in section %u to section %u base=%p\n",
  95                relsec, sym_info, loc_base);
  96
  97         for (i = 0; i < nrelocs; i++) {
  98
  99                 /* Symbol to relocate */
 100                 sym = sym_base + ELF32_R_SYM(rela[i].r_info);
 101
 102                 /* Where to make the change */
 103                 location = loc_base + rela[i].r_offset;
 104
 105                 /* `Everything is relative'. */
 106                 value = sym->st_value + rela[i].r_addend;
 107
 108                 DEBUGP("%d: value=%08x loc=%p reloc=%d symbol=%s\n",
 109                        i, value, location, ELF32_R_TYPE(rela[i].r_info),
 110                        sym->st_name ?
 111                        &strtab[sym->st_name] : "(anonymous)");
 112
 113                 switch (ELF32_R_TYPE(rela[i].r_info)) {
 114                 case R_HEXAGON_B22_PCREL: {
 115                         int dist = (int)(value - (uint32_t)location);
 116                         if ((dist < -0x00800000) ||
 117                             (dist >= 0x00800000)) {
 118                                 printk(KERN_ERR
 119                                        "%s: %s: %08x=%08x-%08x %s\n",
 120                                        module->name,
 121                                        "R_HEXAGON_B22_PCREL reloc out of range",
 122                                        dist, value, (uint32_t)location,
 123                                        sym->st_name ?
 124                                        &strtab[sym->st_name] : "(anonymous)");
 125                                 return -ENOEXEC;
 126                         }
 127                         DEBUGP("B22_PCREL contents: %08X.\n", *location);
 128                         *location &= ~0x01ff3fff;
 129                         *location |= 0x00003fff & dist;
 130                         *location |= 0x01ff0000 & (dist<<2);
 131                         DEBUGP("Contents after reloc: %08x\n", *location);
 132                         break;
 133                 }
 134                 case R_HEXAGON_HI16:
 135                         value = (value>>16) & 0xffff;
 136                         /* fallthrough */
 137                 case R_HEXAGON_LO16:
 138                         *location &= ~0x00c03fff;
 139                         *location |= value & 0x3fff;
 140                         *location |= (value & 0xc000) << 8;
 141                         break;
 142                 case R_HEXAGON_32:
 143                         *location = value;
 144                         break;
 145                 case R_HEXAGON_32_PCREL:
 146                         *location = value - (uint32_t)location;
 147                         break;
 148                 case R_HEXAGON_PLT_B22_PCREL:
 149                 case R_HEXAGON_GOTOFF_LO16:
 150                 case R_HEXAGON_GOTOFF_HI16:
 151                         printk(KERN_ERR "%s: GOT/PLT relocations unsupported\n",
 152                                module->name);
 153                         return -ENOEXEC;
 154                 default:
 155                         printk(KERN_ERR "%s: unknown relocation: %u\n",
 156                                module->name,
 157                                ELF32_R_TYPE(rela[i].r_info));
 158                         return -ENOEXEC;
 159                 }
 160         }
 161         return 0;
 162 }