module.c

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/*
 * OpenRISC module.c
 *
 * Linux architectural port borrowing liberally from similar works of
 * others.  All original copyrights apply as per the original source
 * declaration.
 *
 * Modifications for the OpenRISC architecture:
 * Copyright (C) 2010-2011 Jonas Bonn <[email protected]>
 *
 *      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.
 */

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

int apply_relocate_add(Elf32_Shdr *sechdrs,
               const char *strtab,
               unsigned int symindex,
               unsigned int relsec,
               struct module *me)
{
    unsigned int i;
    Elf32_Rela *rel = (void *)sechdrs[relsec].sh_addr;
    Elf32_Sym *sym;
    uint32_t *location;
    uint32_t value;

    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.  Note that all
           undefined symbols have been resolved.  */
        sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
            + ELF32_R_SYM(rel[i].r_info);
        value = sym->st_value + rel[i].r_addend;

        switch (ELF32_R_TYPE(rel[i].r_info)) {
        case R_OR32_32:
            *location = value;
            break;
        case R_OR32_CONST:
            location = (uint16_t *)location + 1;
            *((uint16_t *)location) = (uint16_t) (value);
            break;
        case R_OR32_CONSTH:
            location = (uint16_t *)location + 1;
            *((uint16_t *)location) = (uint16_t) (value >> 16);
            break;
        case R_OR32_JUMPTARG:
            value -= (uint32_t)location;
            value >>= 2;
            value &= 0x03ffffff;
            value |= *location & 0xfc000000;
            *location = value;
            break;
        default:
            pr_err("module %s: Unknown relocation: %u\n",
                   me->name, ELF32_R_TYPE(rel[i].r_info));
            break;
        }
    }

    return 0;
}