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 #include <arch/elf.h>
16
17 #ifdef LIBELF_USE_DEPRECATED
18 # define elf_getshdrnum elf_getshnum
19 # define elf_getshdrstrndx elf_getshstrndx
20 #endif
21
22 /*
23 * Fallback for systems without this "read, mmaping if possible" cmd.
24 */
25 #ifndef ELF_C_READ_MMAP
26 #define ELF_C_READ_MMAP ELF_C_READ
27 #endif
28
29 struct elf_hash_node {
30 struct elf_hash_node *next;
31 };
32
33 struct section {
34 struct list_head list;
35 struct elf_hash_node hash;
36 struct elf_hash_node name_hash;
37 GElf_Shdr sh;
38 struct rb_root_cached symbol_tree;
39 struct list_head symbol_list;
40 struct section *base, *rsec;
41 struct symbol *sym;
42 Elf_Data *data;
43 char *name;
44 int idx;
45 bool _changed, text, rodata, noinstr, init, truncate;
46 struct reloc *relocs;
47 };
48
49 struct symbol {
50 struct list_head list;
51 struct rb_node node;
52 struct elf_hash_node hash;
53 struct elf_hash_node name_hash;
54 GElf_Sym sym;
55 struct section *sec;
56 char *name;
57 unsigned int idx, len;
58 unsigned long offset;
59 unsigned long __subtree_last;
60 struct symbol *pfunc, *cfunc, *alias;
61 unsigned char bind, type;
62 u8 uaccess_safe : 1;
63 u8 static_call_tramp : 1;
64 u8 retpoline_thunk : 1;
65 u8 return_thunk : 1;
66 u8 fentry : 1;
67 u8 profiling_func : 1;
68 u8 warned : 1;
69 u8 embedded_insn : 1;
70 struct list_head pv_target;
71 struct reloc *relocs;
72 };
73
74 struct reloc {
75 struct elf_hash_node hash;
76 struct section *sec;
77 struct symbol *sym;
78 struct reloc *sym_next_reloc;
79 };
80
81 struct elf {
82 Elf *elf;
83 GElf_Ehdr ehdr;
84 int fd;
85 bool changed;
86 char *name;
87 unsigned int num_files;
88 struct list_head sections;
89 unsigned long num_relocs;
90
91 int symbol_bits;
92 int symbol_name_bits;
93 int section_bits;
94 int section_name_bits;
95 int reloc_bits;
96
97 struct elf_hash_node **symbol_hash;
98 struct elf_hash_node **symbol_name_hash;
99 struct elf_hash_node **section_hash;
100 struct elf_hash_node **section_name_hash;
101 struct elf_hash_node **reloc_hash;
102
103 struct section *section_data;
104 struct symbol *symbol_data;
105 };
106
107 struct elf *elf_open_read(const char *name, int flags);
108
109 struct section *elf_create_section(struct elf *elf, const char *name,
110 size_t entsize, unsigned int nr);
111 struct section *elf_create_section_pair(struct elf *elf, const char *name,
112 size_t entsize, unsigned int nr,
113 unsigned int reloc_nr);
114
115 struct symbol *elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long size);
116
117 struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
118 unsigned long offset,
119 unsigned int reloc_idx,
120 struct section *insn_sec,
121 unsigned long insn_off);
122
123 struct reloc *elf_init_reloc_data_sym(struct elf *elf, struct section *sec,
124 unsigned long offset,
125 unsigned int reloc_idx,
126 struct symbol *sym,
127 s64 addend);
128
129 int elf_write_insn(struct elf *elf, struct section *sec,
130 unsigned long offset, unsigned int len,
131 const char *insn);
132 int elf_write(struct elf *elf);
133 void elf_close(struct elf *elf);
134
135 struct section *find_section_by_name(const struct elf *elf, const char *name);
136 struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
137 struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
138 struct symbol *find_symbol_by_name(const struct elf *elf, const char *name);
139 struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset);
140 int find_symbol_hole_containing(const struct section *sec, unsigned long offset);
141 struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset);
142 struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
143 unsigned long offset, unsigned int len);
144 struct symbol *find_func_containing(struct section *sec, unsigned long offset);
145
146 /*
147 * Try to see if it's a whole archive (vmlinux.o or module).
148 *
149 * Note this will miss the case where a module only has one source file.
150 */
has_multiple_files(struct elf * elf)151 static inline bool has_multiple_files(struct elf *elf)
152 {
153 return elf->num_files > 1;
154 }
155
elf_addr_size(struct elf * elf)156 static inline size_t elf_addr_size(struct elf *elf)
157 {
158 return elf->ehdr.e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8;
159 }
160
elf_rela_size(struct elf * elf)161 static inline size_t elf_rela_size(struct elf *elf)
162 {
163 return elf_addr_size(elf) == 4 ? sizeof(Elf32_Rela) : sizeof(Elf64_Rela);
164 }
165
elf_data_rela_type(struct elf * elf)166 static inline unsigned int elf_data_rela_type(struct elf *elf)
167 {
168 return elf_addr_size(elf) == 4 ? R_DATA32 : R_DATA64;
169 }
170
elf_text_rela_type(struct elf * elf)171 static inline unsigned int elf_text_rela_type(struct elf *elf)
172 {
173 return elf_addr_size(elf) == 4 ? R_TEXT32 : R_TEXT64;
174 }
175
is_reloc_sec(struct section * sec)176 static inline bool is_reloc_sec(struct section *sec)
177 {
178 return sec->sh.sh_type == SHT_RELA || sec->sh.sh_type == SHT_REL;
179 }
180
sec_changed(struct section * sec)181 static inline bool sec_changed(struct section *sec)
182 {
183 return sec->_changed;
184 }
185
mark_sec_changed(struct elf * elf,struct section * sec,bool changed)186 static inline void mark_sec_changed(struct elf *elf, struct section *sec,
187 bool changed)
188 {
189 sec->_changed = changed;
190 elf->changed |= changed;
191 }
192
sec_num_entries(struct section * sec)193 static inline unsigned int sec_num_entries(struct section *sec)
194 {
195 return sec->sh.sh_size / sec->sh.sh_entsize;
196 }
197
reloc_idx(struct reloc * reloc)198 static inline unsigned int reloc_idx(struct reloc *reloc)
199 {
200 return reloc - reloc->sec->relocs;
201 }
202
reloc_rel(struct reloc * reloc)203 static inline void *reloc_rel(struct reloc *reloc)
204 {
205 struct section *rsec = reloc->sec;
206
207 return rsec->data->d_buf + (reloc_idx(reloc) * rsec->sh.sh_entsize);
208 }
209
is_32bit_reloc(struct reloc * reloc)210 static inline bool is_32bit_reloc(struct reloc *reloc)
211 {
212 /*
213 * Elf32_Rel: 8 bytes
214 * Elf32_Rela: 12 bytes
215 * Elf64_Rel: 16 bytes
216 * Elf64_Rela: 24 bytes
217 */
218 return reloc->sec->sh.sh_entsize < 16;
219 }
220
221 #define __get_reloc_field(reloc, field) \
222 ({ \
223 is_32bit_reloc(reloc) ? \
224 ((Elf32_Rela *)reloc_rel(reloc))->field : \
225 ((Elf64_Rela *)reloc_rel(reloc))->field; \
226 })
227
228 #define __set_reloc_field(reloc, field, val) \
229 ({ \
230 if (is_32bit_reloc(reloc)) \
231 ((Elf32_Rela *)reloc_rel(reloc))->field = val; \
232 else \
233 ((Elf64_Rela *)reloc_rel(reloc))->field = val; \
234 })
235
reloc_offset(struct reloc * reloc)236 static inline u64 reloc_offset(struct reloc *reloc)
237 {
238 return __get_reloc_field(reloc, r_offset);
239 }
240
set_reloc_offset(struct elf * elf,struct reloc * reloc,u64 offset)241 static inline void set_reloc_offset(struct elf *elf, struct reloc *reloc, u64 offset)
242 {
243 __set_reloc_field(reloc, r_offset, offset);
244 mark_sec_changed(elf, reloc->sec, true);
245 }
246
reloc_addend(struct reloc * reloc)247 static inline s64 reloc_addend(struct reloc *reloc)
248 {
249 return __get_reloc_field(reloc, r_addend);
250 }
251
set_reloc_addend(struct elf * elf,struct reloc * reloc,s64 addend)252 static inline void set_reloc_addend(struct elf *elf, struct reloc *reloc, s64 addend)
253 {
254 __set_reloc_field(reloc, r_addend, addend);
255 mark_sec_changed(elf, reloc->sec, true);
256 }
257
258
reloc_sym(struct reloc * reloc)259 static inline unsigned int reloc_sym(struct reloc *reloc)
260 {
261 u64 info = __get_reloc_field(reloc, r_info);
262
263 return is_32bit_reloc(reloc) ?
264 ELF32_R_SYM(info) :
265 ELF64_R_SYM(info);
266 }
267
reloc_type(struct reloc * reloc)268 static inline unsigned int reloc_type(struct reloc *reloc)
269 {
270 u64 info = __get_reloc_field(reloc, r_info);
271
272 return is_32bit_reloc(reloc) ?
273 ELF32_R_TYPE(info) :
274 ELF64_R_TYPE(info);
275 }
276
set_reloc_sym(struct elf * elf,struct reloc * reloc,unsigned int sym)277 static inline void set_reloc_sym(struct elf *elf, struct reloc *reloc, unsigned int sym)
278 {
279 u64 info = is_32bit_reloc(reloc) ?
280 ELF32_R_INFO(sym, reloc_type(reloc)) :
281 ELF64_R_INFO(sym, reloc_type(reloc));
282
283 __set_reloc_field(reloc, r_info, info);
284
285 mark_sec_changed(elf, reloc->sec, true);
286 }
set_reloc_type(struct elf * elf,struct reloc * reloc,unsigned int type)287 static inline void set_reloc_type(struct elf *elf, struct reloc *reloc, unsigned int type)
288 {
289 u64 info = is_32bit_reloc(reloc) ?
290 ELF32_R_INFO(reloc_sym(reloc), type) :
291 ELF64_R_INFO(reloc_sym(reloc), type);
292
293 __set_reloc_field(reloc, r_info, info);
294
295 mark_sec_changed(elf, reloc->sec, true);
296 }
297
298 #define for_each_sec(file, sec) \
299 list_for_each_entry(sec, &file->elf->sections, list)
300
301 #define sec_for_each_sym(sec, sym) \
302 list_for_each_entry(sym, &sec->symbol_list, list)
303
304 #define for_each_sym(file, sym) \
305 for (struct section *__sec, *__fake = (struct section *)1; \
306 __fake; __fake = NULL) \
307 for_each_sec(file, __sec) \
308 sec_for_each_sym(__sec, sym)
309
310 #define for_each_reloc(rsec, reloc) \
311 for (int __i = 0, __fake = 1; __fake; __fake = 0) \
312 for (reloc = rsec->relocs; \
313 __i < sec_num_entries(rsec); \
314 __i++, reloc++)
315
316 #define for_each_reloc_from(rsec, reloc) \
317 for (int __i = reloc_idx(reloc); \
318 __i < sec_num_entries(rsec); \
319 __i++, reloc++)
320
321 #define OFFSET_STRIDE_BITS 4
322 #define OFFSET_STRIDE (1UL << OFFSET_STRIDE_BITS)
323 #define OFFSET_STRIDE_MASK (~(OFFSET_STRIDE - 1))
324
325 #define for_offset_range(_offset, _start, _end) \
326 for (_offset = ((_start) & OFFSET_STRIDE_MASK); \
327 _offset >= ((_start) & OFFSET_STRIDE_MASK) && \
328 _offset <= ((_end) & OFFSET_STRIDE_MASK); \
329 _offset += OFFSET_STRIDE)
330
sec_offset_hash(struct section * sec,unsigned long offset)331 static inline u32 sec_offset_hash(struct section *sec, unsigned long offset)
332 {
333 u32 ol, oh, idx = sec->idx;
334
335 offset &= OFFSET_STRIDE_MASK;
336
337 ol = offset;
338 oh = (offset >> 16) >> 16;
339
340 __jhash_mix(ol, oh, idx);
341
342 return ol;
343 }
344
reloc_hash(struct reloc * reloc)345 static inline u32 reloc_hash(struct reloc *reloc)
346 {
347 return sec_offset_hash(reloc->sec, reloc_offset(reloc));
348 }
349
350 #endif /* _OBJTOOL_ELF_H */
351