Revert "x86/mm: Stop calling leave_mm() in idle code"
[sfrench/cifs-2.6.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/kasan.h>
28 #include <linux/bug.h>
29 #include <linux/mm.h>
30 #include <linux/gfp.h>
31 #include <linux/jump_label.h>
32 #include <linux/random.h>
33
34 #include <asm/text-patching.h>
35 #include <asm/page.h>
36 #include <asm/pgtable.h>
37 #include <asm/setup.h>
38 #include <asm/unwind.h>
39
40 #if 0
41 #define DEBUGP(fmt, ...)                                \
42         printk(KERN_DEBUG fmt, ##__VA_ARGS__)
43 #else
44 #define DEBUGP(fmt, ...)                                \
45 do {                                                    \
46         if (0)                                          \
47                 printk(KERN_DEBUG fmt, ##__VA_ARGS__);  \
48 } while (0)
49 #endif
50
51 #ifdef CONFIG_RANDOMIZE_BASE
52 static unsigned long module_load_offset;
53
54 /* Mutex protects the module_load_offset. */
55 static DEFINE_MUTEX(module_kaslr_mutex);
56
57 static unsigned long int get_module_load_offset(void)
58 {
59         if (kaslr_enabled()) {
60                 mutex_lock(&module_kaslr_mutex);
61                 /*
62                  * Calculate the module_load_offset the first time this
63                  * code is called. Once calculated it stays the same until
64                  * reboot.
65                  */
66                 if (module_load_offset == 0)
67                         module_load_offset =
68                                 (get_random_int() % 1024 + 1) * PAGE_SIZE;
69                 mutex_unlock(&module_kaslr_mutex);
70         }
71         return module_load_offset;
72 }
73 #else
74 static unsigned long int get_module_load_offset(void)
75 {
76         return 0;
77 }
78 #endif
79
80 void *module_alloc(unsigned long size)
81 {
82         void *p;
83
84         if (PAGE_ALIGN(size) > MODULES_LEN)
85                 return NULL;
86
87         p = __vmalloc_node_range(size, MODULE_ALIGN,
88                                     MODULES_VADDR + get_module_load_offset(),
89                                     MODULES_END, GFP_KERNEL,
90                                     PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
91                                     __builtin_return_address(0));
92         if (p && (kasan_module_alloc(p, size) < 0)) {
93                 vfree(p);
94                 return NULL;
95         }
96
97         return p;
98 }
99
100 #ifdef CONFIG_X86_32
101 int apply_relocate(Elf32_Shdr *sechdrs,
102                    const char *strtab,
103                    unsigned int symindex,
104                    unsigned int relsec,
105                    struct module *me)
106 {
107         unsigned int i;
108         Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
109         Elf32_Sym *sym;
110         uint32_t *location;
111
112         DEBUGP("Applying relocate section %u to %u\n",
113                relsec, sechdrs[relsec].sh_info);
114         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
115                 /* This is where to make the change */
116                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
117                         + rel[i].r_offset;
118                 /* This is the symbol it is referring to.  Note that all
119                    undefined symbols have been resolved.  */
120                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
121                         + ELF32_R_SYM(rel[i].r_info);
122
123                 switch (ELF32_R_TYPE(rel[i].r_info)) {
124                 case R_386_32:
125                         /* We add the value into the location given */
126                         *location += sym->st_value;
127                         break;
128                 case R_386_PC32:
129                         /* Add the value, subtract its position */
130                         *location += sym->st_value - (uint32_t)location;
131                         break;
132                 default:
133                         pr_err("%s: Unknown relocation: %u\n",
134                                me->name, ELF32_R_TYPE(rel[i].r_info));
135                         return -ENOEXEC;
136                 }
137         }
138         return 0;
139 }
140 #else /*X86_64*/
141 int apply_relocate_add(Elf64_Shdr *sechdrs,
142                    const char *strtab,
143                    unsigned int symindex,
144                    unsigned int relsec,
145                    struct module *me)
146 {
147         unsigned int i;
148         Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
149         Elf64_Sym *sym;
150         void *loc;
151         u64 val;
152
153         DEBUGP("Applying relocate section %u to %u\n",
154                relsec, sechdrs[relsec].sh_info);
155         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
156                 /* This is where to make the change */
157                 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
158                         + rel[i].r_offset;
159
160                 /* This is the symbol it is referring to.  Note that all
161                    undefined symbols have been resolved.  */
162                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
163                         + ELF64_R_SYM(rel[i].r_info);
164
165                 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
166                        (int)ELF64_R_TYPE(rel[i].r_info),
167                        sym->st_value, rel[i].r_addend, (u64)loc);
168
169                 val = sym->st_value + rel[i].r_addend;
170
171                 switch (ELF64_R_TYPE(rel[i].r_info)) {
172                 case R_X86_64_NONE:
173                         break;
174                 case R_X86_64_64:
175                         *(u64 *)loc = val;
176                         break;
177                 case R_X86_64_32:
178                         *(u32 *)loc = val;
179                         if (val != *(u32 *)loc)
180                                 goto overflow;
181                         break;
182                 case R_X86_64_32S:
183                         *(s32 *)loc = val;
184                         if ((s64)val != *(s32 *)loc)
185                                 goto overflow;
186                         break;
187                 case R_X86_64_PC32:
188                         val -= (u64)loc;
189                         *(u32 *)loc = val;
190 #if 0
191                         if ((s64)val != *(s32 *)loc)
192                                 goto overflow;
193 #endif
194                         break;
195                 default:
196                         pr_err("%s: Unknown rela relocation: %llu\n",
197                                me->name, ELF64_R_TYPE(rel[i].r_info));
198                         return -ENOEXEC;
199                 }
200         }
201         return 0;
202
203 overflow:
204         pr_err("overflow in relocation type %d val %Lx\n",
205                (int)ELF64_R_TYPE(rel[i].r_info), val);
206         pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
207                me->name);
208         return -ENOEXEC;
209 }
210 #endif
211
212 int module_finalize(const Elf_Ehdr *hdr,
213                     const Elf_Shdr *sechdrs,
214                     struct module *me)
215 {
216         const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
217                 *para = NULL, *orc = NULL, *orc_ip = NULL;
218         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
219
220         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
221                 if (!strcmp(".text", secstrings + s->sh_name))
222                         text = s;
223                 if (!strcmp(".altinstructions", secstrings + s->sh_name))
224                         alt = s;
225                 if (!strcmp(".smp_locks", secstrings + s->sh_name))
226                         locks = s;
227                 if (!strcmp(".parainstructions", secstrings + s->sh_name))
228                         para = s;
229                 if (!strcmp(".orc_unwind", secstrings + s->sh_name))
230                         orc = s;
231                 if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
232                         orc_ip = s;
233         }
234
235         if (alt) {
236                 /* patch .altinstructions */
237                 void *aseg = (void *)alt->sh_addr;
238                 apply_alternatives(aseg, aseg + alt->sh_size);
239         }
240         if (locks && text) {
241                 void *lseg = (void *)locks->sh_addr;
242                 void *tseg = (void *)text->sh_addr;
243                 alternatives_smp_module_add(me, me->name,
244                                             lseg, lseg + locks->sh_size,
245                                             tseg, tseg + text->sh_size);
246         }
247
248         if (para) {
249                 void *pseg = (void *)para->sh_addr;
250                 apply_paravirt(pseg, pseg + para->sh_size);
251         }
252
253         /* make jump label nops */
254         jump_label_apply_nops(me);
255
256         if (orc && orc_ip)
257                 unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,
258                                    (void *)orc->sh_addr, orc->sh_size);
259
260         return 0;
261 }
262
263 void module_arch_cleanup(struct module *mod)
264 {
265         alternatives_smp_module_del(mod);
266 }