x86: Constify a few items
[linux-3.10.git] / arch / x86 / kernel / module.c
1 /*  Kernel module help for x86.
2     Copyright (C) 2001 Rusty Russell.
3
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.
8
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.
13
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
17 */
18
19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21 #include <linux/moduleloader.h>
22 #include <linux/elf.h>
23 #include <linux/vmalloc.h>
24 #include <linux/fs.h>
25 #include <linux/string.h>
26 #include <linux/kernel.h>
27 #include <linux/bug.h>
28 #include <linux/mm.h>
29 #include <linux/gfp.h>
30 #include <linux/jump_label.h>
31
32 #include <asm/page.h>
33 #include <asm/pgtable.h>
34
35 #if 0
36 #define DEBUGP(fmt, ...)                                \
37         printk(KERN_DEBUG fmt, ##__VA_ARGS__)
38 #else
39 #define DEBUGP(fmt, ...)                                \
40 do {                                                    \
41         if (0)                                          \
42                 printk(KERN_DEBUG fmt, ##__VA_ARGS__);  \
43 } while (0)
44 #endif
45
46 void *module_alloc(unsigned long size)
47 {
48         if (PAGE_ALIGN(size) > MODULES_LEN)
49                 return NULL;
50         return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
51                                 GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC,
52                                 -1, __builtin_return_address(0));
53 }
54
55 #ifdef CONFIG_X86_32
56 int apply_relocate(Elf32_Shdr *sechdrs,
57                    const char *strtab,
58                    unsigned int symindex,
59                    unsigned int relsec,
60                    struct module *me)
61 {
62         unsigned int i;
63         Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
64         Elf32_Sym *sym;
65         uint32_t *location;
66
67         DEBUGP("Applying relocate section %u to %u\n",
68                relsec, sechdrs[relsec].sh_info);
69         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
70                 /* This is where to make the change */
71                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
72                         + rel[i].r_offset;
73                 /* This is the symbol it is referring to.  Note that all
74                    undefined symbols have been resolved.  */
75                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
76                         + ELF32_R_SYM(rel[i].r_info);
77
78                 switch (ELF32_R_TYPE(rel[i].r_info)) {
79                 case R_386_32:
80                         /* We add the value into the location given */
81                         *location += sym->st_value;
82                         break;
83                 case R_386_PC32:
84                         /* Add the value, subtract its position */
85                         *location += sym->st_value - (uint32_t)location;
86                         break;
87                 default:
88                         pr_err("%s: Unknown relocation: %u\n",
89                                me->name, ELF32_R_TYPE(rel[i].r_info));
90                         return -ENOEXEC;
91                 }
92         }
93         return 0;
94 }
95 #else /*X86_64*/
96 int apply_relocate_add(Elf64_Shdr *sechdrs,
97                    const char *strtab,
98                    unsigned int symindex,
99                    unsigned int relsec,
100                    struct module *me)
101 {
102         unsigned int i;
103         Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
104         Elf64_Sym *sym;
105         void *loc;
106         u64 val;
107
108         DEBUGP("Applying relocate section %u to %u\n",
109                relsec, sechdrs[relsec].sh_info);
110         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
111                 /* This is where to make the change */
112                 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
113                         + rel[i].r_offset;
114
115                 /* This is the symbol it is referring to.  Note that all
116                    undefined symbols have been resolved.  */
117                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
118                         + ELF64_R_SYM(rel[i].r_info);
119
120                 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
121                        (int)ELF64_R_TYPE(rel[i].r_info),
122                        sym->st_value, rel[i].r_addend, (u64)loc);
123
124                 val = sym->st_value + rel[i].r_addend;
125
126                 switch (ELF64_R_TYPE(rel[i].r_info)) {
127                 case R_X86_64_NONE:
128                         break;
129                 case R_X86_64_64:
130                         *(u64 *)loc = val;
131                         break;
132                 case R_X86_64_32:
133                         *(u32 *)loc = val;
134                         if (val != *(u32 *)loc)
135                                 goto overflow;
136                         break;
137                 case R_X86_64_32S:
138                         *(s32 *)loc = val;
139                         if ((s64)val != *(s32 *)loc)
140                                 goto overflow;
141                         break;
142                 case R_X86_64_PC32:
143                         val -= (u64)loc;
144                         *(u32 *)loc = val;
145 #if 0
146                         if ((s64)val != *(s32 *)loc)
147                                 goto overflow;
148 #endif
149                         break;
150                 default:
151                         pr_err("%s: Unknown rela relocation: %llu\n",
152                                me->name, ELF64_R_TYPE(rel[i].r_info));
153                         return -ENOEXEC;
154                 }
155         }
156         return 0;
157
158 overflow:
159         pr_err("overflow in relocation type %d val %Lx\n",
160                (int)ELF64_R_TYPE(rel[i].r_info), val);
161         pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
162                me->name);
163         return -ENOEXEC;
164 }
165 #endif
166
167 int module_finalize(const Elf_Ehdr *hdr,
168                     const Elf_Shdr *sechdrs,
169                     struct module *me)
170 {
171         const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
172                 *para = NULL;
173         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
174
175         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
176                 if (!strcmp(".text", secstrings + s->sh_name))
177                         text = s;
178                 if (!strcmp(".altinstructions", secstrings + s->sh_name))
179                         alt = s;
180                 if (!strcmp(".smp_locks", secstrings + s->sh_name))
181                         locks = s;
182                 if (!strcmp(".parainstructions", secstrings + s->sh_name))
183                         para = s;
184         }
185
186         if (alt) {
187                 /* patch .altinstructions */
188                 void *aseg = (void *)alt->sh_addr;
189                 apply_alternatives(aseg, aseg + alt->sh_size);
190         }
191         if (locks && text) {
192                 void *lseg = (void *)locks->sh_addr;
193                 void *tseg = (void *)text->sh_addr;
194                 alternatives_smp_module_add(me, me->name,
195                                             lseg, lseg + locks->sh_size,
196                                             tseg, tseg + text->sh_size);
197         }
198
199         if (para) {
200                 void *pseg = (void *)para->sh_addr;
201                 apply_paravirt(pseg, pseg + para->sh_size);
202         }
203
204         /* make jump label nops */
205         jump_label_apply_nops(me);
206
207         return 0;
208 }
209
210 void module_arch_cleanup(struct module *mod)
211 {
212         alternatives_smp_module_del(mod);
213 }