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