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/kasan.h>
28 #include <linux/bug.h>
30 #include <linux/gfp.h>
31 #include <linux/jump_label.h>
32 #include <linux/random.h>
35 #include <asm/pgtable.h>
38 #define DEBUGP(fmt, ...) \
39 printk(KERN_DEBUG fmt, ##__VA_ARGS__)
41 #define DEBUGP(fmt, ...) \
44 printk(KERN_DEBUG fmt, ##__VA_ARGS__); \
48 #ifdef CONFIG_RANDOMIZE_BASE
49 static unsigned long module_load_offset;
50 static int randomize_modules = 1;
52 /* Mutex protects the module_load_offset. */
53 static DEFINE_MUTEX(module_kaslr_mutex);
55 static int __init parse_nokaslr(char *p)
57 randomize_modules = 0;
60 early_param("nokaslr", parse_nokaslr);
62 static unsigned long int get_module_load_offset(void)
64 if (randomize_modules) {
65 mutex_lock(&module_kaslr_mutex);
67 * Calculate the module_load_offset the first time this
68 * code is called. Once calculated it stays the same until
71 if (module_load_offset == 0)
73 (get_random_int() % 1024 + 1) * PAGE_SIZE;
74 mutex_unlock(&module_kaslr_mutex);
76 return module_load_offset;
79 static unsigned long int get_module_load_offset(void)
85 void *module_alloc(unsigned long size)
89 if (PAGE_ALIGN(size) > MODULES_LEN)
92 p = __vmalloc_node_range(size, MODULE_ALIGN,
93 MODULES_VADDR + get_module_load_offset(),
94 MODULES_END, GFP_KERNEL | __GFP_HIGHMEM,
95 PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
96 __builtin_return_address(0));
97 if (p && (kasan_module_alloc(p, size) < 0)) {
106 int apply_relocate(Elf32_Shdr *sechdrs,
108 unsigned int symindex,
113 Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
117 DEBUGP("Applying relocate section %u to %u\n",
118 relsec, sechdrs[relsec].sh_info);
119 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
120 /* This is where to make the change */
121 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
123 /* This is the symbol it is referring to. Note that all
124 undefined symbols have been resolved. */
125 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
126 + ELF32_R_SYM(rel[i].r_info);
128 switch (ELF32_R_TYPE(rel[i].r_info)) {
130 /* We add the value into the location given */
131 *location += sym->st_value;
134 /* Add the value, subtract its position */
135 *location += sym->st_value - (uint32_t)location;
138 pr_err("%s: Unknown relocation: %u\n",
139 me->name, ELF32_R_TYPE(rel[i].r_info));
146 int apply_relocate_add(Elf64_Shdr *sechdrs,
148 unsigned int symindex,
153 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
158 DEBUGP("Applying relocate section %u to %u\n",
159 relsec, sechdrs[relsec].sh_info);
160 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
161 /* This is where to make the change */
162 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
165 /* This is the symbol it is referring to. Note that all
166 undefined symbols have been resolved. */
167 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
168 + ELF64_R_SYM(rel[i].r_info);
170 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
171 (int)ELF64_R_TYPE(rel[i].r_info),
172 sym->st_value, rel[i].r_addend, (u64)loc);
174 val = sym->st_value + rel[i].r_addend;
176 switch (ELF64_R_TYPE(rel[i].r_info)) {
184 if (val != *(u32 *)loc)
189 if ((s64)val != *(s32 *)loc)
196 if ((s64)val != *(s32 *)loc)
201 pr_err("%s: Unknown rela relocation: %llu\n",
202 me->name, ELF64_R_TYPE(rel[i].r_info));
209 pr_err("overflow in relocation type %d val %Lx\n",
210 (int)ELF64_R_TYPE(rel[i].r_info), val);
211 pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
217 int module_finalize(const Elf_Ehdr *hdr,
218 const Elf_Shdr *sechdrs,
221 const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
223 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
225 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
226 if (!strcmp(".text", secstrings + s->sh_name))
228 if (!strcmp(".altinstructions", secstrings + s->sh_name))
230 if (!strcmp(".smp_locks", secstrings + s->sh_name))
232 if (!strcmp(".parainstructions", secstrings + s->sh_name))
237 /* patch .altinstructions */
238 void *aseg = (void *)alt->sh_addr;
239 apply_alternatives(aseg, aseg + alt->sh_size);
242 void *lseg = (void *)locks->sh_addr;
243 void *tseg = (void *)text->sh_addr;
244 alternatives_smp_module_add(me, me->name,
245 lseg, lseg + locks->sh_size,
246 tseg, tseg + text->sh_size);
250 void *pseg = (void *)para->sh_addr;
251 apply_paravirt(pseg, pseg + para->sh_size);
254 /* make jump label nops */
255 jump_label_apply_nops(me);
260 void module_arch_cleanup(struct module *mod)
262 alternatives_smp_module_del(mod);