arch/arc/kernel/module.c

   1 /*
   2  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   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 version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/moduleloader.h>
  11 #include <linux/kernel.h>
  12 #include <linux/elf.h>
  13 #include <linux/vmalloc.h>
  14 #include <linux/slab.h>
  15 #include <linux/fs.h>
  16 #include <linux/string.h>
  17 #include <asm/unwind.h>
  18
  19 static inline void arc_write_me(unsigned short *addr, unsigned long value)
  20 {
  21         *addr = (value & 0xffff0000) >> 16;
  22         *(addr + 1) = (value & 0xffff);
  23 }
  24
  25 /*
  26  * This gets called before relocation loop in generic loader
  27  * Make a note of the section index of unwinding section
  28  */
  29 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
  30                               char *secstr, struct module *mod)
  31 {
  32 #ifdef CONFIG_ARC_DW2_UNWIND
  33         mod->arch.unw_sec_idx = 0;
  34         mod->arch.unw_info = NULL;
  35 #endif
  36         mod->arch.secstr = secstr;
  37         return 0;
  38 }
  39
  40 void module_arch_cleanup(struct module *mod)
  41 {
  42 #ifdef CONFIG_ARC_DW2_UNWIND
  43         if (mod->arch.unw_info)
  44                 unwind_remove_table(mod->arch.unw_info, 0);
  45 #endif
  46 }
  47
  48 int apply_relocate_add(Elf32_Shdr *sechdrs,
  49                        const char *strtab,
  50                        unsigned int symindex,   /* sec index for sym tbl */
  51                        unsigned int relsec,     /* sec index for relo sec */
  52                        struct module *module)
  53 {
  54         int i, n, relo_type;
  55         Elf32_Rela *rel_entry = (void *)sechdrs[relsec].sh_addr;
  56         Elf32_Sym *sym_entry, *sym_sec;
  57         Elf32_Addr relocation, location, tgt_addr;
  58         unsigned int tgtsec;
  59
  60         /*
  61          * @relsec has relocations e.g. .rela.init.text
  62          * @tgtsec is section to patch e.g. .init.text
  63          */
  64         tgtsec = sechdrs[relsec].sh_info;
  65         tgt_addr = sechdrs[tgtsec].sh_addr;
  66         sym_sec = (Elf32_Sym *) sechdrs[symindex].sh_addr;
  67         n = sechdrs[relsec].sh_size / sizeof(*rel_entry);
  68
  69         pr_debug("\nSection to fixup %s @%x\n",
  70                  module->arch.secstr + sechdrs[tgtsec].sh_name, tgt_addr);
  71         pr_debug("=========================================================\n");
  72         pr_debug("r_off\tr_add\tst_value ADDRESS  VALUE\n");
  73         pr_debug("=========================================================\n");
  74
  75         /* Loop thru entries in relocation section */
  76         for (i = 0; i < n; i++) {
  77                 const char *s;
  78
  79                 /* This is where to make the change */
  80                 location = tgt_addr + rel_entry[i].r_offset;
  81
  82                 /* This is the symbol it is referring to.  Note that all
  83                    undefined symbols have been resolved.  */
  84                 sym_entry = sym_sec + ELF32_R_SYM(rel_entry[i].r_info);
  85
  86                 relocation = sym_entry->st_value + rel_entry[i].r_addend;
  87
  88                 if (sym_entry->st_name == 0 && ELF_ST_TYPE (sym_entry->st_info) == STT_SECTION) {
  89                         s = module->arch.secstr + sechdrs[sym_entry->st_shndx].sh_name;
  90                 } else {
  91                         s = strtab + sym_entry->st_name;
  92                 }
  93
  94                 pr_debug("   %x\t%x\t%x %x %x [%s]\n",
  95                          rel_entry[i].r_offset, rel_entry[i].r_addend,
  96                          sym_entry->st_value, location, relocation, s);
  97
  98                 /* This assumes modules are built with -mlong-calls
  99                  * so any branches/jumps are absolute 32 bit jmps
 100                  * global data access again is abs 32 bit.
 101                  * Both of these are handled by same relocation type
 102                  */
 103                 relo_type = ELF32_R_TYPE(rel_entry[i].r_info);
 104
 105                 if (likely(R_ARC_32_ME == relo_type))   /* ME ( S + A ) */
 106                         arc_write_me((unsigned short *)location, relocation);
 107                 else if (R_ARC_32 == relo_type)         /* ( S + A ) */
 108                         *((Elf32_Addr *) location) = relocation;
 109                 else if (R_ARC_32_PCREL == relo_type)   /* ( S + A ) - PDATA ) */
 110                         *((Elf32_Addr *) location) = relocation - location;
 111                 else
 112                         goto relo_err;
 113
 114         }
 115
 116 #ifdef CONFIG_ARC_DW2_UNWIND
 117         if (strcmp(module->arch.secstr+sechdrs[tgtsec].sh_name, ".eh_frame") == 0)
 118                 module->arch.unw_sec_idx = tgtsec;
 119 #endif
 120
 121         return 0;
 122
 123 relo_err:
 124         pr_err("%s: unknown relocation: %u\n",
 125                 module->name, ELF32_R_TYPE(rel_entry[i].r_info));
 126         return -ENOEXEC;
 127
 128 }
 129
 130 /* Just before lift off: After sections have been relocated, we add the
 131  * dwarf section to unwinder table pool
 132  * This couldn't be done in module_frob_arch_sections() because
 133  * relocations had not been applied by then
 134  */
 135 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 136                     struct module *mod)
 137 {
 138 #ifdef CONFIG_ARC_DW2_UNWIND
 139         void *unw;
 140         int unwsec = mod->arch.unw_sec_idx;
 141
 142         if (unwsec) {
 143                 unw = unwind_add_table(mod, (void *)sechdrs[unwsec].sh_addr,
 144                                        sechdrs[unwsec].sh_size);
 145                 mod->arch.unw_info = unw;
 146         }
 147 #endif
 148         return 0;
 149 }