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/*

 * Copyright (c) 2006 Sergey Bondari

 * Copyright (c) 2006 Jakub Jermar

 * 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 generic

 * @{

 */

/**

 * @file

 * @brief   Kernel ELF loader.

 */

#include <stdio.h>

#include <sys/types.h>

#include <align.h>

#include <assert.h>

#include <as.h>

#include "elf.h"

#define RTLD_BIAS 0x80000

//#define RTLD_BIAS 0

static char *error_codes[] = {

    "no error",

    "invalid image",

    "address space error",

    "incompatible image",

    "unsupported image type",

    "irrecoverable error"

};

static int segment_header(int fd, elf_header_t *elf);

static int section_header(int fd, elf_header_t *elf);

static int load_segment(int fd, elf_segment_header_t *entry, elf_header_t *elf);

typedef void (*epoint_t)(void);

/** ELF loader

 *

 * @param header Pointer to ELF header in memory

 * @return EE_OK on success

 */

unsigned int elf_load(int fd, elf_header_t *header)

{

    int i, rc;

    rc = read(fd, header, sizeof(elf_header_t));

    if (rc < 0) {

        printf("read error\n");

        return EE_INVALID;

    }

    printf("ELF-load:");

    /* Identify ELF */

    if (header->e_ident[EI_MAG0] != ELFMAG0 ||

        header->e_ident[EI_MAG1] != ELFMAG1 ||

        header->e_ident[EI_MAG2] != ELFMAG2 ||

        header->e_ident[EI_MAG3] != ELFMAG3) {

        printf("invalid header\n");

        return EE_INVALID;

    }

    /* Identify ELF compatibility */

    if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||

        header->e_machine != ELF_MACHINE ||

        header->e_ident[EI_VERSION] != EV_CURRENT ||

        header->e_version != EV_CURRENT ||

        header->e_ident[EI_CLASS] != ELF_CLASS) {

        printf("incompatible data/version/class\n");

        return EE_INCOMPATIBLE;

    }

    if (header->e_phentsize != sizeof(elf_segment_header_t))

        return EE_INCOMPATIBLE;

    if (header->e_shentsize != sizeof(elf_section_header_t))

        return EE_INCOMPATIBLE;

    /* Check if the object type is supported. */

    if (header->e_type != ET_EXEC && header->e_type != ET_DYN) {

        printf("Object type %d is not supported\n", header->e_type);

        return EE_UNSUPPORTED;

    }

    if (header->e_type == ET_DYN) header->e_entry += RTLD_BIAS;

    printf("parse segments\n");

    /* Walk through all segment headers and process them. */

    for (i = 0; i < header->e_phnum; i++) {

        /* Seek to start of segment header */

        lseek(fd, header->e_phoff + i * sizeof(elf_segment_header_t),

            SEEK_SET);

        rc = segment_header(fd, header);

        if (rc != EE_OK)

            return rc;

    }

    printf("parse sections\n");

    /* Inspect all section headers and proccess them. */

    for (i = 0; i < header->e_shnum; i++) {

        /* Seek to start of section header */

        lseek(fd, header->e_shoff + i * sizeof(elf_section_header_t),

            SEEK_SET);

        rc = section_header(fd, header);

        if (rc != EE_OK)

            return rc;

    }

    printf("done\n");

    return EE_OK;

}

/** Print error message according to error code.

 *

 * @param rc Return code returned by elf_load().

 *

 * @return NULL terminated description of error.

 */

char *elf_error(unsigned int rc)

{

    assert(rc < sizeof(error_codes) / sizeof(char *));

    return error_codes[rc];

}

/** Process segment header.

 *

 * @param entry Segment header.

 * @param elf ELF header.

 *

 * @return EE_OK on success, error code otherwise.

 */

static int segment_header(int fd, elf_header_t *elf)

{

    static elf_segment_header_t entry_buf;

    elf_segment_header_t *entry = &entry_buf;

    int rc;

    rc = read(fd, entry, sizeof(elf_segment_header_t));

    if (rc < 0) { printf("read error\n"); return EE_INVALID; }

    switch (entry->p_type) {

    case PT_NULL:

    case PT_PHDR:

        break;

    case PT_LOAD:

        return load_segment(fd, entry, elf);

        break;

    case PT_DYNAMIC:

    case PT_INTERP:

    case PT_SHLIB:

    case PT_NOTE:

    case PT_LOPROC:

    case PT_HIPROC:

    default:

        printf("segment p_type %d unknown\n", entry->p_type);

        return EE_UNSUPPORTED;

        break;

    }

    return EE_OK;

}

/** Load segment described by program header entry.

 *

 * @param entry Program header entry describing segment to be loaded.

 * @param elf ELF header.

 *

 * @return EE_OK on success, error code otherwise.

 */

int load_segment(int fd, elf_segment_header_t *entry, elf_header_t *elf)

{

    void *a;

    int flags = 0;

    uintptr_t bias;

    int rc;

    printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr,

        entry->p_memsz);

    bias = (elf->e_type == ET_DYN) ? RTLD_BIAS : 0;

    if (entry->p_align > 1) {

        if ((entry->p_offset % entry->p_align) !=

            (entry->p_vaddr % entry->p_align)) {

            printf("align check 1 failed offset%%align=%d, vaddr%%align=%d\n",

            entry->p_offset % entry->p_align,

            entry->p_vaddr % entry->p_align

            );

            return EE_INVALID;

        }

    }

/*  if (entry->p_flags & PF_X)

        flags |= AS_AREA_EXEC;

    if (entry->p_flags & PF_W)

        flags |= AS_AREA_WRITE;

    if (entry->p_flags & PF_R)

        flags |= AS_AREA_READ;

    flags |= AS_AREA_CACHEABLE;

*/

    /* FIXME: Kernel won't normally allow this, unless you "patch" it */

//  flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_EXEC | AS_AREA_CACHEABLE;

    flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE;

    /*

     * Check if the virtual address starts on page boundary.

     */

    if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr) {

        printf("align check 2 failed - not page-aligned\n");

        printf("vaddr = 0x%x, should be 0x%x\n",

            entry->p_vaddr, ALIGN_UP(entry->p_vaddr, PAGE_SIZE));

        return EE_UNSUPPORTED;

    }

    printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias,

    entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE));

    a = as_area_create((uint8_t *)entry->p_vaddr + bias,

        entry->p_memsz, flags);

    if (a == (void *)(-1)) {

        printf("memory mapping failed\n");

        return EE_MEMORY;

    }

    printf("as_area_create(0x%x, 0x%x, %d) -> 0x%x\n",

        entry->p_vaddr+bias, entry->p_memsz, flags, (unsigned)a);

    /*

     * Load segment data

     */

    printf("seek to %d\n", entry->p_offset);

    rc = lseek(fd, entry->p_offset, SEEK_SET);

    if (rc < 0) { printf("seek error\n"); return EE_INVALID; }

    printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias);

/*  rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz);

    if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/

    unsigned left, now;

    uint8_t *dp;

    left = entry->p_filesz;

    dp = (uint8_t *)(entry->p_vaddr + bias);

    while (left > 0) {

        now = 4096;

        if (now > left) now=left;

        printf("read %d...", now);

        rc = read(fd, dp, now);

        if (rc < 0) { printf("read error\n"); return EE_INVALID; }

        printf("->%d\n", rc);

        left -= now;

        dp += now;

    }

    return EE_OK;

}

/** Process section header.

 *

 * @param entry Segment header.

 * @param elf ELF header.

 *

 * @return EE_OK on success, error code otherwise.

 */

static int section_header(int fd, elf_header_t *elf)

{

    static elf_section_header_t entry_buf;

    elf_section_header_t *entry = &entry_buf;

    int rc;

    rc = read(fd, entry, sizeof(elf_section_header_t));

    if (rc < 0) { printf("read error\n"); return EE_INVALID; }

    switch (entry->sh_type) {

    case SHT_PROGBITS:

        if (entry->sh_flags & SHF_TLS) {

            /* .tdata */

        }

        break;

    case SHT_NOBITS:

        if (entry->sh_flags & SHF_TLS) {

            /* .tbss */

        }

        break;

    case SHT_DYNAMIC:

        printf("dynamic section found\n");

        break;

    default:

        break;

    }

    return EE_OK;

}

/** @}

 */