1 /* Kernel module help for x86.
2 Copyright (C) 2001 Rusty Russell.
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21 #include <linux/moduleloader.h>
22 #include <linux/elf.h>
23 #include <linux/vmalloc.h>
25 #include <linux/string.h>
26 #include <linux/kernel.h>
27 #include <linux/bug.h>
29 #include <linux/gfp.h>
30 #include <linux/jump_label.h>
31 #include <linux/random.h>
34 #include <asm/pgtable.h>
37 #define DEBUGP(fmt, ...) \
38 printk(KERN_DEBUG fmt, ##__VA_ARGS__)
40 #define DEBUGP(fmt, ...) \
43 printk(KERN_DEBUG fmt, ##__VA_ARGS__); \
47 #ifdef CONFIG_RANDOMIZE_BASE
48 static unsigned long module_load_offset
;
49 static int randomize_modules
= 1;
51 /* Mutex protects the module_load_offset. */
52 static DEFINE_MUTEX(module_kaslr_mutex
);
54 static int __init
parse_nokaslr(char *p
)
56 randomize_modules
= 0;
59 early_param("nokaslr", parse_nokaslr
);
61 static unsigned long int get_module_load_offset(void)
63 if (randomize_modules
) {
64 mutex_lock(&module_kaslr_mutex
);
66 * Calculate the module_load_offset the first time this
67 * code is called. Once calculated it stays the same until
70 if (module_load_offset
== 0)
72 (get_random_int() % 1024 + 1) * PAGE_SIZE
;
73 mutex_unlock(&module_kaslr_mutex
);
75 return module_load_offset
;
78 static unsigned long int get_module_load_offset(void)
84 void *module_alloc(unsigned long size
)
86 if (PAGE_ALIGN(size
) > MODULES_LEN
)
88 return __vmalloc_node_range(size
, 1,
89 MODULES_VADDR
+ get_module_load_offset(),
90 MODULES_END
, GFP_KERNEL
| __GFP_HIGHMEM
,
91 PAGE_KERNEL_EXEC
, NUMA_NO_NODE
,
92 __builtin_return_address(0));
96 int apply_relocate(Elf32_Shdr
*sechdrs
,
98 unsigned int symindex
,
103 Elf32_Rel
*rel
= (void *)sechdrs
[relsec
].sh_addr
;
107 DEBUGP("Applying relocate section %u to %u\n",
108 relsec
, sechdrs
[relsec
].sh_info
);
109 for (i
= 0; i
< sechdrs
[relsec
].sh_size
/ sizeof(*rel
); i
++) {
110 /* This is where to make the change */
111 location
= (void *)sechdrs
[sechdrs
[relsec
].sh_info
].sh_addr
113 /* This is the symbol it is referring to. Note that all
114 undefined symbols have been resolved. */
115 sym
= (Elf32_Sym
*)sechdrs
[symindex
].sh_addr
116 + ELF32_R_SYM(rel
[i
].r_info
);
118 switch (ELF32_R_TYPE(rel
[i
].r_info
)) {
120 /* We add the value into the location given */
121 *location
+= sym
->st_value
;
124 /* Add the value, subtract its position */
125 *location
+= sym
->st_value
- (uint32_t)location
;
128 pr_err("%s: Unknown relocation: %u\n",
129 me
->name
, ELF32_R_TYPE(rel
[i
].r_info
));
136 int apply_relocate_add(Elf64_Shdr
*sechdrs
,
138 unsigned int symindex
,
143 Elf64_Rela
*rel
= (void *)sechdrs
[relsec
].sh_addr
;
148 DEBUGP("Applying relocate section %u to %u\n",
149 relsec
, sechdrs
[relsec
].sh_info
);
150 for (i
= 0; i
< sechdrs
[relsec
].sh_size
/ sizeof(*rel
); i
++) {
151 /* This is where to make the change */
152 loc
= (void *)sechdrs
[sechdrs
[relsec
].sh_info
].sh_addr
155 /* This is the symbol it is referring to. Note that all
156 undefined symbols have been resolved. */
157 sym
= (Elf64_Sym
*)sechdrs
[symindex
].sh_addr
158 + ELF64_R_SYM(rel
[i
].r_info
);
160 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
161 (int)ELF64_R_TYPE(rel
[i
].r_info
),
162 sym
->st_value
, rel
[i
].r_addend
, (u64
)loc
);
164 val
= sym
->st_value
+ rel
[i
].r_addend
;
166 switch (ELF64_R_TYPE(rel
[i
].r_info
)) {
174 if (val
!= *(u32
*)loc
)
179 if ((s64
)val
!= *(s32
*)loc
)
186 if ((s64
)val
!= *(s32
*)loc
)
191 pr_err("%s: Unknown rela relocation: %llu\n",
192 me
->name
, ELF64_R_TYPE(rel
[i
].r_info
));
199 pr_err("overflow in relocation type %d val %Lx\n",
200 (int)ELF64_R_TYPE(rel
[i
].r_info
), val
);
201 pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
207 int module_finalize(const Elf_Ehdr
*hdr
,
208 const Elf_Shdr
*sechdrs
,
211 const Elf_Shdr
*s
, *text
= NULL
, *alt
= NULL
, *locks
= NULL
,
213 char *secstrings
= (void *)hdr
+ sechdrs
[hdr
->e_shstrndx
].sh_offset
;
215 for (s
= sechdrs
; s
< sechdrs
+ hdr
->e_shnum
; s
++) {
216 if (!strcmp(".text", secstrings
+ s
->sh_name
))
218 if (!strcmp(".altinstructions", secstrings
+ s
->sh_name
))
220 if (!strcmp(".smp_locks", secstrings
+ s
->sh_name
))
222 if (!strcmp(".parainstructions", secstrings
+ s
->sh_name
))
227 /* patch .altinstructions */
228 void *aseg
= (void *)alt
->sh_addr
;
229 apply_alternatives(aseg
, aseg
+ alt
->sh_size
);
232 void *lseg
= (void *)locks
->sh_addr
;
233 void *tseg
= (void *)text
->sh_addr
;
234 alternatives_smp_module_add(me
, me
->name
,
235 lseg
, lseg
+ locks
->sh_size
,
236 tseg
, tseg
+ text
->sh_size
);
240 void *pseg
= (void *)para
->sh_addr
;
241 apply_paravirt(pseg
, pseg
+ para
->sh_size
);
244 /* make jump label nops */
245 jump_label_apply_nops(me
);
250 void module_arch_cleanup(struct module
*mod
)
252 alternatives_smp_module_del(mod
);
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