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/*

 * Copyright (c) 2008 Jiri Svoboda

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/** @addtogroup rtld rtld

 * @brief

 * @{

 */

/**

 * @file

 */

#include <stdio.h>

#include <stdlib.h>

#include <arch.h>

#include <elf_dyn.h>

#include <symbol.h>

#include <rtld.h>

#include <smc.h>

#define __L(ptr) ((uint32_t)(ptr) & 0x0000ffff)

#define __HA(ptr) ((uint32_t)(ptr) >> 16)

// ldis r11, .PLTtable@ha

static inline uint32_t _ldis(unsigned rD, uint16_t imm16)

{

    /* Special case of addis: ldis rD,SIMM == addis rD,0,SIMM */

    return 0x3C000000 | (rD << 21) | imm16;

}

static inline uint32_t _lwz(unsigned rD, uint16_t disp16, unsigned rA)

{

    return 0x80000000 | (rD << 21) | (rA << 16) | disp16;

}

static inline uint32_t _mtctr(unsigned rS)

{

    /* mtctr rD == mtspr 9, rD */

    return 0x7c0003a6 | (rS << 21) | (9/*CTR*/ << 16);

}

static inline uint32_t _bctr()

{

    /* bcctr 0x1f, 0 */

    return 0x4c000420 | (0x1f/*always*/ << 21);

}

/* branch */

static inline uint32_t _b(uint32_t *addr, uint32_t *location)

{

    uint32_t raddr = ((uint32_t)addr - (uint32_t)location) & 0x03fffffc;

    return 0x48000000 | raddr;

}

/*

 * Fill in PLT

 */

void module_process_pre_arch(module_t *m)

{

    uint32_t *plt;

    uint32_t *_plt_ent;

    plt = m->dyn.plt_got;

    if (!plt) {

        /* Module has no PLT */

        return;

    }

    // PLT entries start here. However, each occupies 2 words

    _plt_ent = plt + 18;

    // By definition of the ppc ABI, there's 1:1 correspondence

    // between JMPREL entries and PLT entries

    unsigned plt_n = m->dyn.plt_rel_sz / sizeof(elf_rela_t);

    uint32_t *_plt_table;

    uint32_t *_plt_call;

    uint32_t *_plt_resolve;

    _plt_resolve = plt;

    _plt_call = plt + 6;

    _plt_table = plt + 18 + plt_n;

/* .PLTcall: */

    plt[6] = _ldis(11, __HA(_plt_table));   // ldis r11, .PLTtable@ha

    plt[7] = _lwz(11, __L(_plt_table), 11); // lwz r11, .PLTtable@l(r11)

    plt[8] = _mtctr(11);            // mtctr r11

    plt[9] = _bctr();

/* .PLTi, i = 0..N-1 */

//  kputint(-4);

/*  for (i = 0; i < plt_n; ++i) {

        //_plt_table[i] == function address;

        plt[18+i] = _b(_plt_call, &plt[18+i]);  // b .PLTcall

    }*/

}

void rel_table_process(module_t *m, elf_rel_t *rt, size_t rt_size)

{

    /* Unused */

    (void)m; (void)rt; (void)rt_size;

}

/**

 * Process (fixup) all relocations in a relocation table.

 */

void rela_table_process(module_t *m, elf_rela_t *rt, size_t rt_size)

{

    int i;

    size_t rt_entries;

    size_t r_offset;

    elf_word r_info;

    unsigned rel_type;

    elf_word sym_idx;

    uintptr_t sym_addr;

    uintptr_t r_addend;

    elf_symbol_t *sym_table;

    elf_symbol_t *sym;

    uint32_t *r_ptr;

    uint16_t *r_ptr16;

    char *str_tab;

    elf_symbol_t *sym_def;

    module_t *dest;

    uint32_t *plt;

    uint32_t *_plt_table;

    uint32_t *_plt_ent;

    uint32_t plt_n;

    uint32_t pidx;

    uint32_t t_addr;

    uint32_t sym_size;

    plt = m->dyn.plt_got;

    plt_n = m->dyn.plt_rel_sz / sizeof(elf_rela_t);

    _plt_ent = plt+ 18;

    _plt_table = plt + 18 + plt_n;

    DPRINTF("parse relocation table\n");

    sym_table = m->dyn.sym_tab;

    rt_entries = rt_size / sizeof(elf_rela_t);

    str_tab = m->dyn.str_tab;

    DPRINTF("address: 0x%x, entries: %d\n", (uintptr_t)rt, rt_entries);

    for (i = 0; i < rt_entries; ++i) {

        DPRINTF("symbol %d: ", i);

        r_offset = rt[i].r_offset;

        r_info = rt[i].r_info;

        r_addend = rt[i].r_addend;

        sym_idx = ELF32_R_SYM(r_info);

        sym = &sym_table[sym_idx];

        DPRINTF("name '%s', value 0x%x, size 0x%x\n",

            str_tab + sym->st_name,

            sym->st_value,

            sym->st_size);

        rel_type = ELF32_R_TYPE(r_info);

        r_ptr = (uint32_t *)(r_offset + m->bias);

        r_ptr16 = (uint16_t *)(r_offset + m->bias);

        if (sym->st_name != 0) {

            DPRINTF("rel_type: %x, rel_offset: 0x%x\n", rel_type, r_offset);

            sym_def = symbol_def_find(str_tab + sym->st_name,

                m, &dest);

            DPRINTF("dest name: '%s'\n", dest->dyn.soname);

            DPRINTF("dest bias: 0x%x\n", dest->bias);

            if (sym_def) {

                sym_addr = symbol_get_addr(sym_def, dest);

                DPRINTF("symbol definition found, addr=0x%x\n", sym_addr);

            } else {

                DPRINTF("symbol definition not found\n");

                continue;

            }

        }

        switch (rel_type) {

        case R_PPC_ADDR16_LO:

            DPRINTF("fixup R_PPC_ADDR16_LO (#lo(s+a))\n");

            *r_ptr16 = (sym_addr + r_addend) & 0xffff;

            break;

        case R_PPC_ADDR16_HI:

            DPRINTF("fixup R_PPC_ADDR16_HI (#hi(s+a))\n");

            *r_ptr16 = (sym_addr + r_addend) >> 16;

            break;

        case R_PPC_ADDR16_HA:

            DPRINTF("fixup R_PPC_ADDR16_HA (#ha(s+a))\n");

            t_addr = sym_addr + r_addend;

            *r_ptr16 = (t_addr >> 16) + ((t_addr & 0x8000) ? 1 : 0);

            break;

        case R_PPC_JMP_SLOT:

            DPRINTF("fixup R_PPC_JMP_SLOT (b+v)\n");

            pidx = (r_ptr - _plt_ent) / 2;

            if (pidx >= plt_n) {

                DPRINTF("error: proc index out of range\n");

                exit(1);

            }

            plt[18+2*pidx] = _b((void *)sym_addr, &plt[18+2*pidx]);

            break;

        case R_PPC_ADDR32:

            DPRINTF("fixup R_PPC_ADDR32 (b+v+a)\n");

            *r_ptr = r_addend + sym_addr;

            break;

        case R_PPC_COPY:

            /*

             * Copy symbol data from shared object to specified

             * location.

             */

            DPRINTF("fixup R_PPC_COPY (s)\n");

            sym_size = sym->st_size;

            if (sym_size != sym_def->st_size) {

                printf("warning: mismatched symbol sizes\n");

                /* Take the lower value. */

                if (sym_size > sym_def->st_size)

                    sym_size = sym_def->st_size;

            }

            memcpy(r_ptr, (const void *)sym_addr, sym_size);

            break;

        case R_PPC_RELATIVE:

            DPRINTF("fixup R_PPC_RELATIVE (b+a)\n");

            *r_ptr = r_addend + m->bias;

            break;

        case R_PPC_REL24:

            DPRINTF("fixup R_PPC_REL24 (s+a-p)>>2\n");

            *r_ptr = (sym_addr + r_addend - (uint32_t)r_ptr) >> 2;

            break;

        case R_PPC_DTPMOD32:

            /*

             * We can ignore this as long as the only module

             * with TLS variables is libc.so.

             */

            DPRINTF("Ignoring R_PPC_DTPMOD32\n");

            break;

        default:

            printf("Error: Unknown relocation type %d.\n",

                rel_type);

            exit(1);

            break;

        }

    }

    /*

     * Synchronize the used portion of PLT. This is necessary since

     * we are writing instructions.

     */

    smc_coherence(&plt[18], plt_n * 2 * sizeof(uint32_t));

}

/** @}

 */