/*
 * arch/xtensa/kernel/module.c
 *
 * Module support.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2001 - 2006 Tensilica Inc.
 *
 * Chris Zankel <chris@zankel.net>
 *
 */

#include <linux/module.h>
#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/cache.h>

static int
decode_calln_opcode (unsigned char *location)
{
#ifdef __XTENSA_EB__
        return (location[0] & 0xf0) == 0x50;
#endif
#ifdef __XTENSA_EL__
        return (location[0] & 0xf) == 0x5;
#endif
}

static int
decode_l32r_opcode (unsigned char *location)
{
#ifdef __XTENSA_EB__
        return (location[0] & 0xf0) == 0x10;
#endif
#ifdef __XTENSA_EL__
        return (location[0] & 0xf) == 0x1;
#endif
}

int apply_relocate_add(Elf32_Shdr *sechdrs,
                       const char *strtab,
                       unsigned int symindex,
                       unsigned int relsec,
                       struct module *mod)
{
        unsigned int i;
        Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
        Elf32_Sym *sym;
        unsigned char *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(*rela); i++) {
                location = (char *)sechdrs[sechdrs[relsec].sh_info].sh_addr
                        + rela[i].r_offset;
                sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
                        + ELF32_R_SYM(rela[i].r_info);
                value = sym->st_value + rela[i].r_addend;

                switch (ELF32_R_TYPE(rela[i].r_info)) {
                case R_XTENSA_NONE:
                case R_XTENSA_DIFF8:
                case R_XTENSA_DIFF16:
                case R_XTENSA_DIFF32:
                case R_XTENSA_ASM_EXPAND:
                        break;

                case R_XTENSA_32:
                case R_XTENSA_PLT:
                        *(uint32_t *)location += value;
                        break;

                case R_XTENSA_SLOT0_OP:
                        if (decode_calln_opcode(location)) {
                                value -= ((unsigned long)location & -4) + 4;
                                if ((value & 3) != 0 ||
                                    ((value + (1 << 19)) >> 20) != 0) {
                                        pr_err("%s: relocation out of range, "
                                               "section %d reloc %d "
                                               "sym '%s'\n",
                                               mod->name, relsec, i,
                                               strtab + sym->st_name);
                                        return -ENOEXEC;
                                }
                                value = (signed int)value >> 2;
#ifdef __XTENSA_EB__
                                location[0] = ((location[0] & ~0x3) |
                                            ((value >> 16) & 0x3));
                                location[1] = (value >> 8) & 0xff;
                                location[2] = value & 0xff;
#endif
#ifdef __XTENSA_EL__
                                location[0] = ((location[0] & ~0xc0) |
                                            ((value << 6) & 0xc0));
                                location[1] = (value >> 2) & 0xff;
                                location[2] = (value >> 10) & 0xff;
#endif
                        } else if (decode_l32r_opcode(location)) {
                                value -= (((unsigned long)location + 3) & -4);
                                if ((value & 3) != 0 ||
                                    (signed int)value >> 18 != -1) {
                                        pr_err("%s: relocation out of range, "
                                               "section %d reloc %d "
                                               "sym '%s'\n",
                                               mod->name, relsec, i,
                                               strtab + sym->st_name);
                                        return -ENOEXEC;
                                }
                                value = (signed int)value >> 2;

#ifdef __XTENSA_EB__
                                location[1] = (value >> 8) & 0xff;
                                location[2] = value & 0xff;
#endif
#ifdef __XTENSA_EL__
                                location[1] = value & 0xff;
                                location[2] = (value >> 8) & 0xff;
#endif
                        }
                        /* FIXME: Ignore any other opcodes.  The Xtensa
                           assembler currently assumes that the linker will
                           always do relaxation and so all PC-relative
                           operands need relocations.  (The assembler also
                           writes out the tentative PC-relative values,
                           assuming no link-time relaxation, so it is usually
                           safe to ignore the relocations.)  If the
                           assembler's "--no-link-relax" flag can be made to
                           work, and if all kernel modules can be assembled
                           with that flag, then unexpected relocations could
                           be detected here.  */
                        break;

                case R_XTENSA_SLOT1_OP:
                case R_XTENSA_SLOT2_OP:
                case R_XTENSA_SLOT3_OP:
                case R_XTENSA_SLOT4_OP:
                case R_XTENSA_SLOT5_OP:
                case R_XTENSA_SLOT6_OP:
                case R_XTENSA_SLOT7_OP:
                case R_XTENSA_SLOT8_OP:
                case R_XTENSA_SLOT9_OP:
                case R_XTENSA_SLOT10_OP:
                case R_XTENSA_SLOT11_OP:
                case R_XTENSA_SLOT12_OP:
                case R_XTENSA_SLOT13_OP:
                case R_XTENSA_SLOT14_OP:
                        pr_err("%s: unexpected FLIX relocation: %u\n",
                               mod->name,
                               ELF32_R_TYPE(rela[i].r_info));
                        return -ENOEXEC;

                case R_XTENSA_SLOT0_ALT:
                case R_XTENSA_SLOT1_ALT:
                case R_XTENSA_SLOT2_ALT:
                case R_XTENSA_SLOT3_ALT:
                case R_XTENSA_SLOT4_ALT:
                case R_XTENSA_SLOT5_ALT:
                case R_XTENSA_SLOT6_ALT:
                case R_XTENSA_SLOT7_ALT:
                case R_XTENSA_SLOT8_ALT:
                case R_XTENSA_SLOT9_ALT:
                case R_XTENSA_SLOT10_ALT:
                case R_XTENSA_SLOT11_ALT:
                case R_XTENSA_SLOT12_ALT:
                case R_XTENSA_SLOT13_ALT:
                case R_XTENSA_SLOT14_ALT:
                        pr_err("%s: unexpected ALT relocation: %u\n",
                               mod->name,
                               ELF32_R_TYPE(rela[i].r_info));
                        return -ENOEXEC;

                default:
                        pr_err("%s: unexpected relocation: %u\n",
                               mod->name,
                               ELF32_R_TYPE(rela[i].r_info));
                        return -ENOEXEC;
                }
        }
        return 0;
}