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 /* ARC specific section quirks - before relocation loop in generic loader
  26  *
  27  * For dwarf unwinding out of modules, this needs to
  28  * 1. Ensure the .debug_frame is allocatable (ARC Linker bug: despite
  29  *    -fasynchronous-unwind-tables it doesn't).
  30  * 2. Since we are iterating thru sec hdr tbl anyways, make a note of
  31  *    the exact section index, for later use.
  32  */
  33 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
  34                               char *secstr, struct module *mod)
  35 {
  36 #ifdef CONFIG_ARC_DW2_UNWIND
  37         int i;
  38
  39         mod->arch.unw_sec_idx = 0;
  40         mod->arch.unw_info = NULL;
  41
  42         for (i = 1; i < hdr->e_shnum; i++) {
  43                 if (strcmp(secstr+sechdrs[i].sh_name, ".debug_frame") == 0) {
  44                         sechdrs[i].sh_flags |= SHF_ALLOC;
  45                         mod->arch.unw_sec_idx = i;
  46                         break;
  47                 }
  48         }
  49 #endif
  50         return 0;
  51 }
  52
  53 void module_arch_cleanup(struct module *mod)
  54 {
  55 #ifdef CONFIG_ARC_DW2_UNWIND
  56         if (mod->arch.unw_info)
  57                 unwind_remove_table(mod->arch.unw_info, 0);
  58 #endif
  59 }
  60
  61 int apply_relocate_add(Elf32_Shdr *sechdrs,
  62                        const char *strtab,
  63                        unsigned int symindex,   /* sec index for sym tbl */
  64                        unsigned int relsec,     /* sec index for relo sec */
  65                        struct module *module)
  66 {
  67         int i, n;
  68         Elf32_Rela *rel_entry = (void *)sechdrs[relsec].sh_addr;
  69         Elf32_Sym *sym_entry, *sym_sec;
  70         Elf32_Addr relocation;
  71         Elf32_Addr location;
  72         Elf32_Addr sec_to_patch;
  73         int relo_type;
  74
  75         sec_to_patch = sechdrs[sechdrs[relsec].sh_info].sh_addr;
  76         sym_sec = (Elf32_Sym *) sechdrs[symindex].sh_addr;
  77         n = sechdrs[relsec].sh_size / sizeof(*rel_entry);
  78
  79         pr_debug("\n========== Module Sym reloc ===========================\n");
  80         pr_debug("Section to fixup %x\n", sec_to_patch);
  81         pr_debug("=========================================================\n");
  82         pr_debug("rela->r_off | rela->addend | sym->st_value | ADDR | VALUE\n");
  83         pr_debug("=========================================================\n");
  84
  85         /* Loop thru entries in relocation section */
  86         for (i = 0; i < n; i++) {
  87
  88                 /* This is where to make the change */
  89                 location = sec_to_patch + rel_entry[i].r_offset;
  90
  91                 /* This is the symbol it is referring to.  Note that all
  92                    undefined symbols have been resolved.  */
  93                 sym_entry = sym_sec + ELF32_R_SYM(rel_entry[i].r_info);
  94
  95                 relocation = sym_entry->st_value + rel_entry[i].r_addend;
  96
  97                 pr_debug("\t%x\t\t%x\t\t%x  %x %x [%s]\n",
  98                         rel_entry[i].r_offset, rel_entry[i].r_addend,
  99                         sym_entry->st_value, location, relocation,
 100                         strtab + sym_entry->st_name);
 101
 102                 /* This assumes modules are built with -mlong-calls
 103                  * so any branches/jumps are absolute 32 bit jmps
 104                  * global data access again is abs 32 bit.
 105                  * Both of these are handled by same relocation type
 106                  */
 107                 relo_type = ELF32_R_TYPE(rel_entry[i].r_info);
 108
 109                 if (likely(R_ARC_32_ME == relo_type))
 110                         arc_write_me((unsigned short *)location, relocation);
 111                 else if (R_ARC_32 == relo_type)
 112                         *((Elf32_Addr *) location) = relocation;
 113                 else
 114                         goto relo_err;
 115
 116         }
 117         return 0;
 118
 119 relo_err:
 120         pr_err("%s: unknown relocation: %u\n",
 121                 module->name, ELF32_R_TYPE(rel_entry[i].r_info));
 122         return -ENOEXEC;
 123
 124 }
 125
 126 /* Just before lift off: After sections have been relocated, we add the
 127  * dwarf section to unwinder table pool
 128  * This couldn't be done in module_frob_arch_sections() because
 129  * relocations had not been applied by then
 130  */
 131 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 132                     struct module *mod)
 133 {
 134 #ifdef CONFIG_ARC_DW2_UNWIND
 135         void *unw;
 136         int unwsec = mod->arch.unw_sec_idx;
 137
 138         if (unwsec) {
 139                 unw = unwind_add_table(mod, (void *)sechdrs[unwsec].sh_addr,
 140                                        sechdrs[unwsec].sh_size);
 141                 mod->arch.unw_info = unw;
 142         }
 143 #endif
 144         return 0;
 145 }