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 
28 struct 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 
44 struct 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 	u8 uaccess_safe      : 1;
58 	u8 static_call_tramp : 1;
59 	u8 retpoline_thunk   : 1;
60 	u8 return_thunk      : 1;
61 	u8 fentry            : 1;
62 	u8 profiling_func    : 1;
63 	struct list_head pv_target;
64 };
65 
66 struct reloc {
67 	struct list_head list;
68 	struct hlist_node hash;
69 	union {
70 		GElf_Rela rela;
71 		GElf_Rel  rel;
72 	};
73 	struct section *sec;
74 	struct symbol *sym;
75 	unsigned long offset;
76 	unsigned int type;
77 	s64 addend;
78 	int idx;
79 	bool jump_table_start;
80 };
81 
82 #define ELF_HASH_BITS	20
83 
84 struct elf {
85 	Elf *elf;
86 	GElf_Ehdr ehdr;
87 	int fd;
88 	bool changed;
89 	char *name;
90 	unsigned int text_size, num_files;
91 	struct list_head sections;
92 
93 	int symbol_bits;
94 	int symbol_name_bits;
95 	int section_bits;
96 	int section_name_bits;
97 	int reloc_bits;
98 
99 	struct hlist_head *symbol_hash;
100 	struct hlist_head *symbol_name_hash;
101 	struct hlist_head *section_hash;
102 	struct hlist_head *section_name_hash;
103 	struct hlist_head *reloc_hash;
104 };
105 
106 #define OFFSET_STRIDE_BITS	4
107 #define OFFSET_STRIDE		(1UL << OFFSET_STRIDE_BITS)
108 #define OFFSET_STRIDE_MASK	(~(OFFSET_STRIDE - 1))
109 
110 #define for_offset_range(_offset, _start, _end)			\
111 	for (_offset = ((_start) & OFFSET_STRIDE_MASK);		\
112 	     _offset >= ((_start) & OFFSET_STRIDE_MASK) &&	\
113 	     _offset <= ((_end) & OFFSET_STRIDE_MASK);		\
114 	     _offset += OFFSET_STRIDE)
115 
sec_offset_hash(struct section * sec,unsigned long offset)116 static inline u32 sec_offset_hash(struct section *sec, unsigned long offset)
117 {
118 	u32 ol, oh, idx = sec->idx;
119 
120 	offset &= OFFSET_STRIDE_MASK;
121 
122 	ol = offset;
123 	oh = (offset >> 16) >> 16;
124 
125 	__jhash_mix(ol, oh, idx);
126 
127 	return ol;
128 }
129 
reloc_hash(struct reloc * reloc)130 static inline u32 reloc_hash(struct reloc *reloc)
131 {
132 	return sec_offset_hash(reloc->sec, reloc->offset);
133 }
134 
135 /*
136  * Try to see if it's a whole archive (vmlinux.o or module).
137  *
138  * Note this will miss the case where a module only has one source file.
139  */
has_multiple_files(struct elf * elf)140 static inline bool has_multiple_files(struct elf *elf)
141 {
142 	return elf->num_files > 1;
143 }
144 
145 struct elf *elf_open_read(const char *name, int flags);
146 struct section *elf_create_section(struct elf *elf, const char *name, unsigned int sh_flags, size_t entsize, int nr);
147 
148 int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
149 		  unsigned int type, struct symbol *sym, s64 addend);
150 int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
151 			  unsigned long offset, unsigned int type,
152 			  struct section *insn_sec, unsigned long insn_off);
153 
154 int elf_write_insn(struct elf *elf, struct section *sec,
155 		   unsigned long offset, unsigned int len,
156 		   const char *insn);
157 int elf_write_reloc(struct elf *elf, struct reloc *reloc);
158 int elf_write(struct elf *elf);
159 void elf_close(struct elf *elf);
160 
161 struct section *find_section_by_name(const struct elf *elf, const char *name);
162 struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
163 struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
164 struct symbol *find_symbol_by_name(const struct elf *elf, const char *name);
165 struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset);
166 int find_symbol_hole_containing(const struct section *sec, unsigned long offset);
167 struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset);
168 struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
169 				     unsigned long offset, unsigned int len);
170 struct symbol *find_func_containing(struct section *sec, unsigned long offset);
171 
172 #define for_each_sec(file, sec)						\
173 	list_for_each_entry(sec, &file->elf->sections, list)
174 
175 #endif /* _OBJTOOL_ELF_H */
176