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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

 */

void __main(void);

void __io_init(void);

void __exit(void);

void _rtld_main(void);

#define ELF32_R_SYM(i) ((i)>>8)

#define ELF32_R_TYPE(i) ((unsigned char)(i))

typedef struct {

    int d_tag;

    union {

        unsigned d_val;

        unsigned *d_ptr;

    } d_un;

} elf32_dyn;

typedef struct {

    unsigned r_offset;

    unsigned r_info;

} elf32_rel;

typedef struct {

    unsigned st_name;

    unsigned st_value;

    unsigned st_size;

    unsigned char st_info;

    unsigned char st_other;

    unsigned short st_shndx;

} elf32_sym;

static void kputint(unsigned i)

{

    unsigned dummy;

    asm volatile (

        "movl $30, %%eax;"

        "int $0x30"

        : "=d" (dummy) /* output - %edx clobbered */

        : "d" (i) /* input */

        : "%eax","%ecx" /* all scratch registers clobbered */

    ); 

}

void __bootstrap(void)

{

    unsigned bias;

    unsigned *got;

    elf32_dyn *dynamic;

    unsigned *dptr;

    unsigned dval;

    int i;

    unsigned rel_entries;

    unsigned r_offset;

    unsigned r_info;

    unsigned rel_type;

    unsigned sym_idx;

    unsigned sym_addr;

    elf32_sym *sym_table;

    elf32_rel *rel_table;

    elf32_rel *jmp_rel_table;

    elf32_rel *jmp_rel_entries;

    asm volatile (

    "movl $30, %eax;"

    "int $0x30"

    );

    /* Copied from libc/arch/ia32/entry.s */

/*asm volatile (

    "mov %ss, %ax;"

    "mov %ax, %ds;"

    "mov %ax, %es;"

    "mov %ax, %fs;"

);*/

asm volatile (

    /* Calculate the bias into %0 */

    /* Generates "fake" R_386_RELATIVE run-time relocation */

"   call .L0;"

".L0:   pop %0;"

"   subl $.L0, %0;"

    /* Calculate run-time address of _DYNAMIC into %1 */

    /* Generates "fake" R_386_RELATIVE run-time relocation */

"   movl $_DYNAMIC, %1;"    /* Again, at link time 0-based VMA gets in */

"   addl %0, %1;"       /* Add bias to compute run-time address */

: "=r" (bias), "=r" (dynamic)

);

    kputint(bias);

    kputint((unsigned)dynamic);

    /* parse DYNAMIC */

    got = 0;

    sym_table = 0;

    rel_table = 0;

    rel_entries = 0;

    jmp_rel_table = 0;

    jmp_rel_entries = 0;

    i = 0;

    while (dynamic[i].d_tag != 0) {

        dptr = (unsigned *)(dynamic[i].d_un.d_val + bias);

        dval = dynamic[i].d_un.d_val;

        switch (dynamic[i].d_tag) {

        case 2/* DT_PLTRELSZ */: jmp_rel_entries = dval/8; break;

        case 23/* DT_JMPREL */: jmp_rel_table = dptr; break;

        case 3 /* DT_PLTGOT */:

            /* GOT address */

            got = dptr; break;

        case 6 /* DT_SYMTAB */ : sym_table = dptr; break;

        case 17 /* DT_REL */ : rel_table = dptr; break;

        case 18 /* DT_RELSZ */ : rel_entries = dval / 8; break;

        default: break;

        }

        ++i;

    }

    kputint(1);

    kputint((unsigned)sym_table);

    kputint((unsigned)rel_table);

    kputint((unsigned)rel_entries);

    /* Now relocate all our dynsyms */

    kputint(-1);

    for (i=0; i<rel_entries; i++) {

        kputint(i);

        r_offset = rel_table[i].r_offset;

        r_info = rel_table[i].r_info;

        rel_type = ELF32_R_TYPE(r_info);

        kputint(rel_type);

        kputint(r_offset);

        switch (rel_type) {

        case 6: /* R_386_GLOB_DAT */

        case 7: /* R_386_JUMP_SLOT */

            kputint(16);

            sym_idx = ELF32_R_SYM(r_info);

            sym_addr = sym_table[sym_idx].st_value + bias;

            kputint(sym_idx);

            kputint(sym_addr);

            *(unsigned *)(r_offset+bias) = sym_addr;

            break;

        case 1: /* R_386_32 */

            kputint(16);

            sym_idx = ELF32_R_SYM(r_info);

            sym_addr = sym_table[sym_idx].st_value + bias;

            kputint(sym_idx);

            kputint(sym_addr);

            *(unsigned *)(r_offset+bias) += sym_addr;

            break;

        case 8: /* R_386_RELATIVE */

            kputint(16);

            *(unsigned *)(r_offset+bias) += bias;

            break;

        }

    }

    kputint(-1);

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

        kputint(i);

        r_offset = jmp_rel_table[i].r_offset;

        r_info = jmp_rel_table[i].r_info;

        rel_type = ELF32_R_TYPE(r_info);

        kputint(rel_type);

        kputint(r_offset);

        switch (rel_type) {

        case 6: /* R_386_GLOB_DAT */

        case 7: /* R_386_JUMP_SLOT */

            kputint(16);

            sym_idx = ELF32_R_SYM(r_info);

            sym_addr = sym_table[sym_idx].st_value + bias;

            kputint(sym_idx);

            kputint(sym_addr);

            *(unsigned *)(r_offset+bias) = sym_addr;

            break;

        case 1: /* R_386_32 */

            kputint(16);

            sym_idx = ELF32_R_SYM(r_info);

            sym_addr = sym_table[sym_idx].st_value + bias;

            kputint(sym_idx);

            kputint(sym_addr);

            *(unsigned *)(r_offset+bias) += sym_addr;

            break;

        case 8: /* R_386_RELATIVE */

            kputint(16);

            *(unsigned *)(r_offset+bias) += bias;

            break;

        }

    }

    kputint(-1);

    /* Init libc and run rtld main */

    __main();

    kputint(33);

    __io_init();

    kputint(34);

    _rtld_main();

    kputint(35);

    __exit();

    kputint(36);

    asm (

        "movl $250, %%eax;"

        "int $0x30"

        : /* output */

        : /* input */

        : "%eax","%ecx","%edx" /* all scratch registers clobbered */

    );

}

/** @}

 */