/* MN10300 Kernel module helper routines
 *
 * Copyright (C) 2007, 2008, 2009 Red Hat, Inc. All Rights Reserved.
 * Written by Mark Salter (msalter@redhat.com)
 * - Derived from arch/i386/kernel/module.c
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public Licence as published by
 * the Free Software Foundation; either version 2 of the Licence, 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 Licence for more details.
 *
 * You should have received a copy of the GNU General Public Licence
 * 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/bug.h>

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

/*
 * allocate storage for a module
 */
void *module_alloc(unsigned long size)
{
        if (size == 0)
                return NULL;
        return vmalloc_exec(size);
}

/*
 * free memory returned from module_alloc()
 */
void module_free(struct module *mod, void *module_region)
{
        vfree(module_region);
}

/*
 * allow the arch to fix up the section table
 * - we don't need anything special
 */
int module_frob_arch_sections(Elf_Ehdr *hdr,
                              Elf_Shdr *sechdrs,
                              char *secstrings,
                              struct module *mod)
{
        return 0;
}

static void reloc_put16(uint8_t *p, uint32_t val)
{
        p[0] = val & 0xff;
        p[1] = (val >> 8) & 0xff;
}

static void reloc_put24(uint8_t *p, uint32_t val)
{
        reloc_put16(p, val);
        p[2] = (val >> 16) & 0xff;
}

static void reloc_put32(uint8_t *p, uint32_t val)
{
        reloc_put16(p, val);
        reloc_put16(p+2, val >> 16);
}

/*
 * apply a REL relocation
 */
int apply_relocate(Elf32_Shdr *sechdrs,
                   const char *strtab,
                   unsigned int symindex,
                   unsigned int relsec,
                   struct module *me)
{
        printk(KERN_ERR "module %s: RELOCATION unsupported\n",
               me->name);
        return -ENOEXEC;
}

/*
 * apply a RELA relocation
 */
int apply_relocate_add(Elf32_Shdr *sechdrs,
                       const char *strtab,
                       unsigned int symindex,
                       unsigned int relsec,
                       struct module *me)
{
        unsigned int i, sym_diff_seen = 0;
        Elf32_Rela *rel = (void *)sechdrs[relsec].sh_addr;
        Elf32_Sym *sym;
        Elf32_Addr relocation, sym_diff_val = 0;
        uint8_t *location;
        uint32_t value;

        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 the relocation is referring to (note that
                 * all undefined symbols have been resolved by the caller) */
                sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
                        + ELF32_R_SYM(rel[i].r_info);

                /* this is the adjustment to be made */
                relocation = sym->st_value + rel[i].r_addend;

                if (sym_diff_seen) {
                        switch (ELF32_R_TYPE(rel[i].r_info)) {
                        case R_MN10300_32:
                        case R_MN10300_24:
                        case R_MN10300_16:
                        case R_MN10300_8:
                                relocation -= sym_diff_val;
                                sym_diff_seen = 0;
                                break;
                        default:
                                printk(KERN_ERR "module %s: Unexpected SYM_DIFF relocation: %u\n",
                                       me->name, ELF32_R_TYPE(rel[i].r_info));
                                return -ENOEXEC;
                        }
                }

                switch (ELF32_R_TYPE(rel[i].r_info)) {
                        /* for the first four relocation types, we simply
                         * store the adjustment at the location given */
                case R_MN10300_32:
                        reloc_put32(location, relocation);
                        break;
                case R_MN10300_24:
                        reloc_put24(location, relocation);
                        break;
                case R_MN10300_16:
                        reloc_put16(location, relocation);
                        break;
                case R_MN10300_8:
                        *location = relocation;
                        break;

                        /* for the next three relocation types, we write the
                         * adjustment with the address subtracted over the
                         * value at the location given */
                case R_MN10300_PCREL32:
                        value = relocation - (uint32_t) location;
                        reloc_put32(location, value);
                        break;
                case R_MN10300_PCREL16:
                        value = relocation - (uint32_t) location;
                        reloc_put16(location, value);
                        break;
                case R_MN10300_PCREL8:
                        *location = relocation - (uint32_t) location;
                        break;

                case R_MN10300_SYM_DIFF:
                        /* This is used to adjust the next reloc as required
                         * by relaxation. */
                        sym_diff_seen = 1;
                        sym_diff_val = sym->st_value;
                        break;

                case R_MN10300_ALIGN:
                        /* Just ignore the ALIGN relocs.
                         * Only interesting if kernel performed relaxation. */
                        continue;

                default:
                        printk(KERN_ERR "module %s: Unknown relocation: %u\n",
                               me->name, ELF32_R_TYPE(rel[i].r_info));
                        return -ENOEXEC;
                }
        }
        if (sym_diff_seen) {
                printk(KERN_ERR "module %s: Nothing follows SYM_DIFF relocation: %u\n",
                                       me->name, ELF32_R_TYPE(rel[i].r_info));
                return -ENOEXEC;
        }
        return 0;
}

/*
 * finish loading the module
 */
int module_finalize(const Elf_Ehdr *hdr,
                    const Elf_Shdr *sechdrs,
                    struct module *me)
{
        return module_bug_finalize(hdr, sechdrs, me);
}

/*
 * finish clearing the module
 */
void module_arch_cleanup(struct module *mod)
{
        module_bug_cleanup(mod);
}