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/* Kernel module help for x86.
Copyright (C) 2001 Rusty Russell.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/moduleloader.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/bug.h>
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/jump_label.h>
#include <linux/random.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#if 0
#define DEBUGP(fmt, ...) \
printk(KERN_DEBUG fmt, ##__VA_ARGS__)
#else
#define DEBUGP(fmt, ...) \
do { \
if (0) \
printk(KERN_DEBUG fmt, ##__VA_ARGS__); \
} while (0)
#endif
#ifdef CONFIG_RANDOMIZE_BASE
static unsigned long module_load_offset;
static int randomize_modules = 1;
/* Mutex protects the module_load_offset. */
static DEFINE_MUTEX(module_kaslr_mutex);
static int __init parse_nokaslr(char *p)
{
randomize_modules = 0;
return 0;
}
early_param("nokaslr", parse_nokaslr);
static unsigned long int get_module_load_offset(void)
{
if (randomize_modules) {
mutex_lock(&module_kaslr_mutex);
/*
* Calculate the module_load_offset the first time this
* code is called. Once calculated it stays the same until
* reboot.
*/
if (module_load_offset == 0)
module_load_offset =
(get_random_int() % 1024 + 1) * PAGE_SIZE;
mutex_unlock(&module_kaslr_mutex);
}
return module_load_offset;
}
#else
static unsigned long int get_module_load_offset(void)
{
return 0;
}
#endif
void *module_alloc(unsigned long size)
{
if (PAGE_ALIGN(size) > MODULES_LEN)
return NULL;
return __vmalloc_node_range(size, 1,
MODULES_VADDR + get_module_load_offset(),
MODULES_END, GFP_KERNEL | __GFP_HIGHMEM,
PAGE_KERNEL_EXEC, NUMA_NO_NODE,
__builtin_return_address(0));
}
#ifdef CONFIG_X86_32
int apply_relocate(Elf32_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
unsigned int relsec,
struct module *me)
{
unsigned int i;
Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
Elf32_Sym *sym;
uint32_t *location;
DEBUGP("Applying relocate section %u to %u\n",
relsec, sechdrs[relsec].sh_info);
for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
/* This is where to make the change */
location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+ rel[i].r_offset;
/* This is the symbol it is referring to. Note that all
undefined symbols have been resolved. */
sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
+ ELF32_R_SYM(rel[i].r_info);
switch (ELF32_R_TYPE(rel[i].r_info)) {
case R_386_32:
/* We add the value into the location given */
*location += sym->st_value;
break;
case R_386_PC32:
/* Add the value, subtract its position */
*location += sym->st_value - (uint32_t)location;
break;
default:
pr_err("%s: Unknown relocation: %u\n",
me->name, ELF32_R_TYPE(rel[i].r_info));
return -ENOEXEC;
}
}
return 0;
}
#else /*X86_64*/
int apply_relocate_add(Elf64_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
unsigned int relsec,
struct module *me)
{
unsigned int i;
Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
Elf64_Sym *sym;
void *loc;
u64 val;
DEBUGP("Applying relocate section %u to %u\n",
relsec, sechdrs[relsec].sh_info);
for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
/* This is where to make the change */
loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+ rel[i].r_offset;
/* This is the symbol it is referring to. Note that all
undefined symbols have been resolved. */
sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
+ ELF64_R_SYM(rel[i].r_info);
DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
(int)ELF64_R_TYPE(rel[i].r_info),
sym->st_value, rel[i].r_addend, (u64)loc);
val = sym->st_value + rel[i].r_addend;
switch (ELF64_R_TYPE(rel[i].r_info)) {
case R_X86_64_NONE:
break;
case R_X86_64_64:
*(u64 *)loc = val;
break;
case R_X86_64_32:
*(u32 *)loc = val;
if (val != *(u32 *)loc)
goto overflow;
break;
case R_X86_64_32S:
*(s32 *)loc = val;
if ((s64)val != *(s32 *)loc)
goto overflow;
break;
case R_X86_64_PC32:
val -= (u64)loc;
*(u32 *)loc = val;
#if 0
if ((s64)val != *(s32 *)loc)
goto overflow;
#endif
break;
default:
pr_err("%s: Unknown rela relocation: %llu\n",
me->name, ELF64_R_TYPE(rel[i].r_info));
return -ENOEXEC;
}
}
return 0;
overflow:
pr_err("overflow in relocation type %d val %Lx\n",
(int)ELF64_R_TYPE(rel[i].r_info), val);
pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
me->name);
return -ENOEXEC;
}
#endif
int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *me)
{
const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
*para = NULL;
char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
if (!strcmp(".text", secstrings + s->sh_name))
text = s;
if (!strcmp(".altinstructions", secstrings + s->sh_name))
alt = s;
if (!strcmp(".smp_locks", secstrings + s->sh_name))
locks = s;
if (!strcmp(".parainstructions", secstrings + s->sh_name))
para = s;
}
if (alt) {
/* patch .altinstructions */
void *aseg = (void *)alt->sh_addr;
apply_alternatives(aseg, aseg + alt->sh_size);
}
if (locks && text) {
void *lseg = (void *)locks->sh_addr;
void *tseg = (void *)text->sh_addr;
alternatives_smp_module_add(me, me->name,
lseg, lseg + locks->sh_size,
tseg, tseg + text->sh_size);
}
if (para) {
void *pseg = (void *)para->sh_addr;
apply_paravirt(pseg, pseg + para->sh_size);
}
/* make jump label nops */
jump_label_apply_nops(me);
return 0;
}
void module_arch_cleanup(struct module *mod)
{
alternatives_smp_module_del(mod);
}
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