module-rela.c

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/*
 *  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 ([email protected])
 *  Copyright (C) 2005 Thiemo Seufer
 */

#include <linux/elf.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/moduleloader.h>

extern int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v);

static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)
{
    *location = v;

    return 0;
}

static int apply_r_mips_26_rela(struct module *me, u32 *location, Elf_Addr v)
{
    if (v % 4) {
        pr_err("module %s: dangerous R_MIPS_26 RELArelocation\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) | ((v >> 2) & 0x03ffffff);

    return 0;
}

static int apply_r_mips_hi16_rela(struct module *me, u32 *location, Elf_Addr v)
{
    *location = (*location & 0xffff0000) |
                ((((long long) v + 0x8000LL) >> 16) & 0xffff);

    return 0;
}

static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)
{
    *location = (*location & 0xffff0000) | (v & 0xffff);

    return 0;
}

static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)
{
    *(Elf_Addr *)location = v;

    return 0;
}

static int apply_r_mips_higher_rela(struct module *me, u32 *location,
                    Elf_Addr v)
{
    *location = (*location & 0xffff0000) |
                ((((long long) v + 0x80008000LL) >> 32) & 0xffff);

    return 0;
}

static int apply_r_mips_highest_rela(struct module *me, u32 *location,
                     Elf_Addr v)
{
    *location = (*location & 0xffff0000) |
                ((((long long) v + 0x800080008000LL) >> 48) & 0xffff);

    return 0;
}

static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
                Elf_Addr v) = {
    [R_MIPS_NONE]       = apply_r_mips_none,
    [R_MIPS_32]     = apply_r_mips_32_rela,
    [R_MIPS_26]     = apply_r_mips_26_rela,
    [R_MIPS_HI16]       = apply_r_mips_hi16_rela,
    [R_MIPS_LO16]       = apply_r_mips_lo16_rela,
    [R_MIPS_64]     = apply_r_mips_64_rela,
    [R_MIPS_HIGHER]     = apply_r_mips_higher_rela,
    [R_MIPS_HIGHEST]    = apply_r_mips_highest_rela
};

int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
               unsigned int symindex, unsigned int relsec,
               struct module *me)
{
    Elf_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr;
    Elf_Sym *sym;
    u32 *location;
    unsigned int i;
    Elf_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++) {
        /* 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 = (Elf_Sym *)sechdrs[symindex].sh_addr
            + ELF_MIPS_R_SYM(rel[i]);
        if (IS_ERR_VALUE(sym->st_value)) {
            /* Ignore unresolved weak symbol */
            if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
                continue;
            printk(KERN_WARNING "%s: Unknown symbol %s\n",
                   me->name, strtab + sym->st_name);
            return -ENOENT;
        }

        v = sym->st_value + rel[i].r_addend;

        res = reloc_handlers_rela[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
        if (res)
            return res;
    }

    return 0;
}