linux/arch/x86_64/kernel/module.c

/*  Kernel module help for x86-64
    Copyright (C) 2001 Rusty Russell.
    Copyright (C) 2002,2003 Andi Kleen, SuSE Labs.

    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
*/
#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/slab.h>

#include <asm/system.h>
#include <asm/page.h>
#include <asm/pgtable.h>

#define DEBUGP(fmt...) 

void module_free(struct module *mod, void *module_region)
{
	vfree(module_region);
}

void *module_alloc(unsigned long size)
{
	struct vm_struct *area;

	if (!size)
		return NULL;
	size = PAGE_ALIGN(size);
	if (size > MODULES_LEN)
		return NULL;

	area = __get_vm_area(size, VM_ALLOC, MODULES_VADDR, MODULES_END);
	if (!area)
		return NULL;

	return __vmalloc_area(area, GFP_KERNEL, PAGE_KERNEL_EXEC);
}

/* We don't need anything special. */
int module_frob_arch_sections(Elf_Ehdr *hdr,
			      Elf_Shdr *sechdrs,
			      char *secstrings,
			      struct module *mod)
{
	return 0;
}

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:
			printk(KERN_ERR "module %s: Unknown rela relocation: %Lu\n",
			       me->name, ELF64_R_TYPE(rel[i].r_info));
			return -ENOEXEC;
		}
	}
	return 0;

overflow:
	printk(KERN_ERR "overflow in relocation type %d val %Lx\n", 
	       (int)ELF64_R_TYPE(rel[i].r_info), val);
	printk(KERN_ERR "`%s' likely not compiled with -mcmodel=kernel\n",
	       me->name);
	return -ENOEXEC;
}

int apply_relocate(Elf_Shdr *sechdrs,
		   const char *strtab,
		   unsigned int symindex,
		   unsigned int relsec,
		   struct module *me)
{
	printk("non add relocation not supported\n");
	return -ENOSYS;
} 

extern void apply_alternatives(void *start, void *end); 

int module_finalize(const Elf_Ehdr *hdr,
		    const Elf_Shdr *sechdrs,
		    struct module *me)
{
	const Elf_Shdr *s;
	char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

	/* look for .altinstructions to patch */ 
	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { 
		void *seg; 		
		if (strcmp(".altinstructions", secstrings + s->sh_name))
			continue;
		seg = (void *)s->sh_addr; 
		apply_alternatives(seg, seg + s->sh_size); 
	} 	
	return 0;
}

void module_arch_cleanup(struct module *mod)
{
}