linux/arch/x86/kernel/module.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*  Kernel module help for x86.
    Copyright (C) 2001 Rusty Russell.

*/

#define pr_fmt(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/kasan.h>
#include <linux/bug.h>
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/jump_label.h>
#include <linux/random.h>
#include <linux/memory.h>

#include <asm/text-patching.h>
#include <asm/page.h>
#include <asm/setup.h>
#include <asm/unwind.h>

#if 0
#define DEBUGP …
#else
#define DEBUGP(fmt, ...) …
#endif

#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:
		case R_386_PLT32:
			/* 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*/
static int __write_relocate_add(Elf64_Shdr *sechdrs,
		   const char *strtab,
		   unsigned int symindex,
		   unsigned int relsec,
		   struct module *me,
		   void *(*write)(void *dest, const void *src, size_t len),
		   bool apply)
{ … }

static int write_relocate_add(Elf64_Shdr *sechdrs,
			      const char *strtab,
			      unsigned int symindex,
			      unsigned int relsec,
			      struct module *me,
			      bool apply)
{ … }

int apply_relocate_add(Elf64_Shdr *sechdrs,
		   const char *strtab,
		   unsigned int symindex,
		   unsigned int relsec,
		   struct module *me)
{ … }

#ifdef CONFIG_LIVEPATCH
void clear_relocate_add(Elf64_Shdr *sechdrs,
			const char *strtab,
			unsigned int symindex,
			unsigned int relsec,
			struct module *me)
{
	write_relocate_add(sechdrs, strtab, symindex, relsec, me, false);
}
#endif

#endif

int module_finalize(const Elf_Ehdr *hdr,
		    const Elf_Shdr *sechdrs,
		    struct module *me)
{ … }

void module_arch_cleanup(struct module *mod)
{ … }