arch/arc/kernel/module.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   4  */
   5
   6 #include <linux/module.h>
   7 #include <linux/moduleloader.h>
   8 #include <linux/kernel.h>
   9 #include <linux/elf.h>
  10 #include <linux/vmalloc.h>
  11 #include <linux/slab.h>
  12 #include <linux/fs.h>
  13 #include <linux/string.h>
  14 #include <asm/unwind.h>
  15
  16 static inline void arc_write_me(unsigned short *addr, unsigned long value)
  17 {
  18         *addr = (value & 0xffff0000) >> 16;
  19         *(addr + 1) = (value & 0xffff);
  20 }
  21
  22 /*
  23  * This gets called before relocation loop in generic loader
  24  * Make a note of the section index of unwinding section
  25  */
  26 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
  27                               char *secstr, struct module *mod)
  28 {
  29 #ifdef CONFIG_ARC_DW2_UNWIND
  30         mod->arch.unw_sec_idx = 0;
  31         mod->arch.unw_info = NULL;
  32 #endif
  33         mod->arch.secstr = secstr;
  34         return 0;
  35 }
  36
  37 void module_arch_cleanup(struct module *mod)
  38 {
  39 #ifdef CONFIG_ARC_DW2_UNWIND
  40         if (mod->arch.unw_info)
  41                 unwind_remove_table(mod->arch.unw_info, 0);
  42 #endif
  43 }
  44
  45 int apply_relocate_add(Elf32_Shdr *sechdrs,
  46                        const char *strtab,
  47                        unsigned int symindex,   /* sec index for sym tbl */
  48                        unsigned int relsec,     /* sec index for relo sec */
  49                        struct module *module)
  50 {
  51         int i, n, relo_type;
  52         Elf32_Rela *rel_entry = (void *)sechdrs[relsec].sh_addr;
  53         Elf32_Sym *sym_entry, *sym_sec;
  54         Elf32_Addr relocation, location, tgt_addr;
  55         unsigned int tgtsec;
  56
  57         /*
  58          * @relsec has relocations e.g. .rela.init.text
  59          * @tgtsec is section to patch e.g. .init.text
  60          */
  61         tgtsec = sechdrs[relsec].sh_info;
  62         tgt_addr = sechdrs[tgtsec].sh_addr;
  63         sym_sec = (Elf32_Sym *) sechdrs[symindex].sh_addr;
  64         n = sechdrs[relsec].sh_size / sizeof(*rel_entry);
  65
  66         pr_debug("\nSection to fixup %s @%x\n",
  67                  module->arch.secstr + sechdrs[tgtsec].sh_name, tgt_addr);
  68         pr_debug("=========================================================\n");
  69         pr_debug("r_off\tr_add\tst_value ADDRESS  VALUE\n");
  70         pr_debug("=========================================================\n");
  71
  72         /* Loop thru entries in relocation section */
  73         for (i = 0; i < n; i++) {
  74                 const char *s;
  75
  76                 /* This is where to make the change */
  77                 location = tgt_addr + rel_entry[i].r_offset;
  78
  79                 /* This is the symbol it is referring to.  Note that all
  80                    undefined symbols have been resolved.  */
  81                 sym_entry = sym_sec + ELF32_R_SYM(rel_entry[i].r_info);
  82
  83                 relocation = sym_entry->st_value + rel_entry[i].r_addend;
  84
  85                 if (sym_entry->st_name == 0 && ELF_ST_TYPE (sym_entry->st_info) == STT_SECTION) {
  86                         s = module->arch.secstr + sechdrs[sym_entry->st_shndx].sh_name;
  87                 } else {
  88                         s = strtab + sym_entry->st_name;
  89                 }
  90
  91                 pr_debug("   %x\t%x\t%x %x %x [%s]\n",
  92                          rel_entry[i].r_offset, rel_entry[i].r_addend,
  93                          sym_entry->st_value, location, relocation, s);
  94
  95                 /* This assumes modules are built with -mlong-calls
  96                  * so any branches/jumps are absolute 32 bit jmps
  97                  * global data access again is abs 32 bit.
  98                  * Both of these are handled by same relocation type
  99                  */
 100                 relo_type = ELF32_R_TYPE(rel_entry[i].r_info);
 101
 102                 if (likely(R_ARC_32_ME == relo_type))   /* ME ( S + A ) */
 103                         arc_write_me((unsigned short *)location, relocation);
 104                 else if (R_ARC_32 == relo_type)         /* ( S + A ) */
 105                         *((Elf32_Addr *) location) = relocation;
 106                 else if (R_ARC_32_PCREL == relo_type)   /* ( S + A ) - PDATA ) */
 107                         *((Elf32_Addr *) location) = relocation - location;
 108                 else
 109                         goto relo_err;
 110
 111         }
 112
 113 #ifdef CONFIG_ARC_DW2_UNWIND
 114         if (strcmp(module->arch.secstr+sechdrs[tgtsec].sh_name, ".eh_frame") == 0)
 115                 module->arch.unw_sec_idx = tgtsec;
 116 #endif
 117
 118         return 0;
 119
 120 relo_err:
 121         pr_err("%s: unknown relocation: %u\n",
 122                 module->name, ELF32_R_TYPE(rel_entry[i].r_info));
 123         return -ENOEXEC;
 124
 125 }
 126
 127 /* Just before lift off: After sections have been relocated, we add the
 128  * dwarf section to unwinder table pool
 129  * This couldn't be done in module_frob_arch_sections() because
 130  * relocations had not been applied by then
 131  */
 132 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 133                     struct module *mod)
 134 {
 135 #ifdef CONFIG_ARC_DW2_UNWIND
 136         void *unw;
 137         int unwsec = mod->arch.unw_sec_idx;
 138
 139         if (unwsec) {
 140                 unw = unwind_add_table(mod, (void *)sechdrs[unwsec].sh_addr,
 141                                        sechdrs[unwsec].sh_size);
 142                 mod->arch.unw_info = unw;
 143         }
 144 #endif
 145         return 0;
 146 }