linux/tools/objtool/include/objtool/elf.h
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   1/* SPDX-License-Identifier: GPL-2.0-or-later */
   2/*
   3 * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
   4 */
   5
   6#ifndef _OBJTOOL_ELF_H
   7#define _OBJTOOL_ELF_H
   8
   9#include <stdio.h>
  10#include <gelf.h>
  11#include <linux/list.h>
  12#include <linux/hashtable.h>
  13#include <linux/rbtree.h>
  14#include <linux/jhash.h>
  15
  16#ifdef LIBELF_USE_DEPRECATED
  17# define elf_getshdrnum    elf_getshnum
  18# define elf_getshdrstrndx elf_getshstrndx
  19#endif
  20
  21/*
  22 * Fallback for systems without this "read, mmaping if possible" cmd.
  23 */
  24#ifndef ELF_C_READ_MMAP
  25#define ELF_C_READ_MMAP ELF_C_READ
  26#endif
  27
  28struct section {
  29        struct list_head list;
  30        struct hlist_node hash;
  31        struct hlist_node name_hash;
  32        GElf_Shdr sh;
  33        struct rb_root symbol_tree;
  34        struct list_head symbol_list;
  35        struct list_head reloc_list;
  36        struct section *base, *reloc;
  37        struct symbol *sym;
  38        Elf_Data *data;
  39        char *name;
  40        int idx;
  41        bool changed, text, rodata, noinstr;
  42};
  43
  44struct symbol {
  45        struct list_head list;
  46        struct rb_node node;
  47        struct hlist_node hash;
  48        struct hlist_node name_hash;
  49        GElf_Sym sym;
  50        struct section *sec;
  51        char *name;
  52        unsigned int idx;
  53        unsigned char bind, type;
  54        unsigned long offset;
  55        unsigned int len;
  56        struct symbol *pfunc, *cfunc, *alias;
  57        bool uaccess_safe;
  58        bool static_call_tramp;
  59};
  60
  61struct reloc {
  62        struct list_head list;
  63        struct hlist_node hash;
  64        union {
  65                GElf_Rela rela;
  66                GElf_Rel  rel;
  67        };
  68        struct section *sec;
  69        struct symbol *sym;
  70        unsigned long offset;
  71        unsigned int type;
  72        int addend;
  73        int idx;
  74        bool jump_table_start;
  75};
  76
  77#define ELF_HASH_BITS   20
  78
  79struct elf {
  80        Elf *elf;
  81        GElf_Ehdr ehdr;
  82        int fd;
  83        bool changed;
  84        char *name;
  85        unsigned int text_size;
  86        struct list_head sections;
  87
  88        int symbol_bits;
  89        int symbol_name_bits;
  90        int section_bits;
  91        int section_name_bits;
  92        int reloc_bits;
  93
  94        struct hlist_head *symbol_hash;
  95        struct hlist_head *symbol_name_hash;
  96        struct hlist_head *section_hash;
  97        struct hlist_head *section_name_hash;
  98        struct hlist_head *reloc_hash;
  99};
 100
 101#define OFFSET_STRIDE_BITS      4
 102#define OFFSET_STRIDE           (1UL << OFFSET_STRIDE_BITS)
 103#define OFFSET_STRIDE_MASK      (~(OFFSET_STRIDE - 1))
 104
 105#define for_offset_range(_offset, _start, _end)                 \
 106        for (_offset = ((_start) & OFFSET_STRIDE_MASK);         \
 107             _offset >= ((_start) & OFFSET_STRIDE_MASK) &&      \
 108             _offset <= ((_end) & OFFSET_STRIDE_MASK);          \
 109             _offset += OFFSET_STRIDE)
 110
 111static inline u32 sec_offset_hash(struct section *sec, unsigned long offset)
 112{
 113        u32 ol, oh, idx = sec->idx;
 114
 115        offset &= OFFSET_STRIDE_MASK;
 116
 117        ol = offset;
 118        oh = (offset >> 16) >> 16;
 119
 120        __jhash_mix(ol, oh, idx);
 121
 122        return ol;
 123}
 124
 125static inline u32 reloc_hash(struct reloc *reloc)
 126{
 127        return sec_offset_hash(reloc->sec, reloc->offset);
 128}
 129
 130struct elf *elf_open_read(const char *name, int flags);
 131struct section *elf_create_section(struct elf *elf, const char *name, unsigned int sh_flags, size_t entsize, int nr);
 132
 133int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
 134                  unsigned int type, struct symbol *sym, int addend);
 135int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
 136                          unsigned long offset, unsigned int type,
 137                          struct section *insn_sec, unsigned long insn_off);
 138
 139int elf_write_insn(struct elf *elf, struct section *sec,
 140                   unsigned long offset, unsigned int len,
 141                   const char *insn);
 142int elf_write_reloc(struct elf *elf, struct reloc *reloc);
 143struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name);
 144int elf_write(struct elf *elf);
 145void elf_close(struct elf *elf);
 146
 147struct section *find_section_by_name(const struct elf *elf, const char *name);
 148struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
 149struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
 150struct symbol *find_symbol_by_name(const struct elf *elf, const char *name);
 151struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset);
 152struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset);
 153struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
 154                                     unsigned long offset, unsigned int len);
 155struct symbol *find_func_containing(struct section *sec, unsigned long offset);
 156
 157#define for_each_sec(file, sec)                                         \
 158        list_for_each_entry(sec, &file->elf->sections, list)
 159
 160#endif /* _OBJTOOL_ELF_H */
 161