/*
 *  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
 *
 *  Copyright (C) 2001 Rusty Russell.
 *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
 */

#undef DEBUG

#include <linux/moduleloader.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>

struct mips_hi16 {
        struct mips_hi16 *next;
        Elf32_Addr *addr;
        Elf32_Addr value;
};

static struct mips_hi16 *mips_hi16_list;

void *module_alloc(unsigned long size)
{
        if (size == 0)
                return NULL;
        return vmalloc(size);
}


/* Free memory returned from module_alloc */
void module_free(struct module *mod, void *module_region)
{
        vfree(module_region);
        /* FIXME: If module_region == mod->init_region, trim exception
           table entries. */
}

int module_frob_arch_sections(Elf_Ehdr *hdr,
                              Elf_Shdr *sechdrs,
                              char *secstrings,
                              struct module *mod)
{
        return 0;
}

static int apply_r_mips_none(struct module *me, uint32_t *location,
        Elf32_Addr v)
{
        return 0;
}

static int apply_r_mips_32(struct module *me, uint32_t *location,
        Elf32_Addr v)
{
        *location += v;

        return 0;
}

static int apply_r_mips_26(struct module *me, uint32_t *location,
        Elf32_Addr v)
{
        if (v % 4) {
                printk(KERN_ERR "module %s: dangerous relocation\n", me->name);
                return -ENOEXEC;
        }

        if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
                printk(KERN_ERR
                       "module %s: relocation overflow\n",
                       me->name);
                return -ENOEXEC;
        }

        *location = (*location & ~0x03ffffff) |
                    ((*location + (v >> 2)) & 0x03ffffff);

        return 0;
}

static int apply_r_mips_hi16(struct module *me, uint32_t *location,
        Elf32_Addr v)
{
        struct mips_hi16 *n;

        /*
         * We cannot relocate this one now because we don't know the value of
         * the carry we need to add.  Save the information, and let LO16 do the
         * actual relocation.
         */
        n = kmalloc(sizeof *n, GFP_KERNEL);
        if (!n)
                return -ENOMEM;

        n->addr = location;
        n->value = v;
        n->next = mips_hi16_list;
        mips_hi16_list = n;

        return 0;
}

static int apply_r_mips_lo16(struct module *me, uint32_t *location,
        Elf32_Addr v)
{
        unsigned long insnlo = *location;
        Elf32_Addr val, vallo;

        /* Sign extend the addend we extract from the lo insn.  */
        vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;

        if (mips_hi16_list != NULL) {
                struct mips_hi16 *l;

                l = mips_hi16_list;
                while (l != NULL) {
                        struct mips_hi16 *next;
                        unsigned long insn;

                        /*
                         * The value for the HI16 had best be the same.
                         */
                        if (v != l->value)
                                goto out_danger;

                        /*
                         * Do the HI16 relocation.  Note that we actually don't
                         * need to know anything about the LO16 itself, except
                         * where to find the low 16 bits of the addend needed
                         * by the LO16.
                         */
                        insn = *l->addr;
                        val = ((insn & 0xffff) << 16) + vallo;
                        val += v;

                        /*
                         * Account for the sign extension that will happen in
                         * the low bits.
                         */
                        val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;

                        insn = (insn & ~0xffff) | val;
                        *l->addr = insn;

                        next = l->next;
                        kfree(l);
                        l = next;
                }

                mips_hi16_list = NULL;
        }

        /*
         * Ok, we're done with the HI16 relocs.  Now deal with the LO16.
         */
        val = v + vallo;
        insnlo = (insnlo & ~0xffff) | (val & 0xffff);
        *location = insnlo;

        return 0;

out_danger:
        printk(KERN_ERR "module %s: dangerous " "relocation\n", me->name);

        return -ENOEXEC;
}

static int (*reloc_handlers[]) (struct module *me, uint32_t *location,
        Elf32_Addr v) = {
        [R_MIPS_NONE]   = apply_r_mips_none,
        [R_MIPS_32]     = apply_r_mips_32,
        [R_MIPS_26]     = apply_r_mips_26,
        [R_MIPS_HI16]   = apply_r_mips_hi16,
        [R_MIPS_LO16]   = apply_r_mips_lo16
};

int apply_relocate(Elf32_Shdr *sechdrs,
                   const char *strtab,
                   unsigned int symindex,
                   unsigned int relsec,
                   struct module *me)
{
        Elf32_Rel *rel = (void *) sechdrs[relsec].sh_addr;
        Elf32_Sym *sym;
        uint32_t *location;
        unsigned int i;
        Elf32_Addr v;
        int res;

        pr_debug("Applying relocate section %u to %u\n", relsec,
               sechdrs[relsec].sh_info);

        for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
                Elf32_Word r_info = rel[i].r_info;

                /* 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 */
                sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
                        + ELF32_R_SYM(r_info);
                if (!sym->st_value) {
                        printk(KERN_WARNING "%s: Unknown symbol %s\n",
                               me->name, strtab + sym->st_name);
                        return -ENOENT;
                }

                v = sym->st_value;

                res = reloc_handlers[ELF32_R_TYPE(r_info)](me, location, v);
                if (res)
                        return res;
        }

        return 0;
}

int apply_relocate_add(Elf32_Shdr *sechdrs,
                       const char *strtab,
                       unsigned int symindex,
                       unsigned int relsec,
                       struct module *me)
{
        /*
         * Current binutils always generate .rela relocations.  Keep smiling
         * if it's empty, abort otherwise.
         */
        if (!sechdrs[relsec].sh_size)
                return 0;

        printk(KERN_ERR "module %s: ADD RELOCATION unsupported\n",
               me->name);
        return -ENOEXEC;
}