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;
51 /* Mutex protects the module_load_offset. */
52 static DEFINE_MUTEX(module_kaslr_mutex);
54 static unsigned long int get_module_load_offset(void)
57 mutex_lock(&module_kaslr_mutex);
59 * Calculate the module_load_offset the first time this
60 * code is called. Once calculated it stays the same until
63 if (module_load_offset == 0)
65 (get_random_int() % 1024 + 1) * PAGE_SIZE;
66 mutex_unlock(&module_kaslr_mutex);
68 return module_load_offset;
71 static unsigned long int get_module_load_offset(void)
77 void *module_alloc(unsigned long size)
81 if (PAGE_ALIGN(size) > MODULES_LEN)
84 p = __vmalloc_node_range(size, MODULE_ALIGN,
85 MODULES_VADDR + get_module_load_offset(),
86 MODULES_END, GFP_KERNEL | __GFP_HIGHMEM,
87 PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
88 __builtin_return_address(0));
89 if (p && (kasan_module_alloc(p, size) < 0)) {
98 int apply_relocate(Elf32_Shdr *sechdrs,
100 unsigned int symindex,
105 Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
109 DEBUGP("Applying relocate section %u to %u\n",
110 relsec, sechdrs[relsec].sh_info);
111 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
112 /* This is where to make the change */
113 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
115 /* This is the symbol it is referring to. Note that all
116 undefined symbols have been resolved. */
117 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
118 + ELF32_R_SYM(rel[i].r_info);
120 switch (ELF32_R_TYPE(rel[i].r_info)) {
122 /* We add the value into the location given */
123 *location += sym->st_value;
126 /* Add the value, subtract its position */
127 *location += sym->st_value - (uint32_t)location;
130 pr_err("%s: Unknown relocation: %u\n",
131 me->name, ELF32_R_TYPE(rel[i].r_info));
138 int apply_relocate_add(Elf64_Shdr *sechdrs,
140 unsigned int symindex,
145 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
150 DEBUGP("Applying relocate section %u to %u\n",
151 relsec, sechdrs[relsec].sh_info);
152 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
153 /* This is where to make the change */
154 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
157 /* This is the symbol it is referring to. Note that all
158 undefined symbols have been resolved. */
159 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
160 + ELF64_R_SYM(rel[i].r_info);
162 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
163 (int)ELF64_R_TYPE(rel[i].r_info),
164 sym->st_value, rel[i].r_addend, (u64)loc);
166 val = sym->st_value + rel[i].r_addend;
168 switch (ELF64_R_TYPE(rel[i].r_info)) {
176 if (val != *(u32 *)loc)
181 if ((s64)val != *(s32 *)loc)
188 if ((s64)val != *(s32 *)loc)
193 pr_err("%s: Unknown rela relocation: %llu\n",
194 me->name, ELF64_R_TYPE(rel[i].r_info));
201 pr_err("overflow in relocation type %d val %Lx\n",
202 (int)ELF64_R_TYPE(rel[i].r_info), val);
203 pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
209 int module_finalize(const Elf_Ehdr *hdr,
210 const Elf_Shdr *sechdrs,
213 const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
215 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
217 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
218 if (!strcmp(".text", secstrings + s->sh_name))
220 if (!strcmp(".altinstructions", secstrings + s->sh_name))
222 if (!strcmp(".smp_locks", secstrings + s->sh_name))
224 if (!strcmp(".parainstructions", secstrings + s->sh_name))
229 /* patch .altinstructions */
230 void *aseg = (void *)alt->sh_addr;
231 apply_alternatives(aseg, aseg + alt->sh_size);
234 void *lseg = (void *)locks->sh_addr;
235 void *tseg = (void *)text->sh_addr;
236 alternatives_smp_module_add(me, me->name,
237 lseg, lseg + locks->sh_size,
238 tseg, tseg + text->sh_size);
242 void *pseg = (void *)para->sh_addr;
243 apply_paravirt(pseg, pseg + para->sh_size);
246 /* make jump label nops */
247 jump_label_apply_nops(me);
252 void module_arch_cleanup(struct module *mod)
254 alternatives_smp_module_del(mod);