Subversion Repositories HelenOS

/*

 * Copyright (c) 2006 Sergey Bondari

 * Copyright (c) 2006 Jakub Jermar

 * 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 <lib/elf.h>

#include <debug.h>

#include <arch/types.h>

#include <mm/as.h>

#include <mm/frame.h>

#include <mm/slab.h>

#include <align.h>

#include <memstr.h>

#include <macros.h>

#include <arch.h>

static char *error_codes[] = {

    "no error",

    "invalid image",

    "address space error",

    "incompatible image",

    "unsupported image type",

    "irrecoverable error"

};

static int segment_header(elf_segment_header_t *entry, elf_header_t *elf,

    as_t *as);

static int section_header(elf_section_header_t *entry, elf_header_t *elf,

    as_t *as);

static int load_segment(elf_segment_header_t *entry, elf_header_t *elf,

    as_t *as);

/** ELF loader

 *

 * @param header Pointer to ELF header in memory

 * @param as Created and properly mapped address space

 * @return EE_OK on success

 */

unsigned int elf_load(elf_header_t *header, as_t * as)

{

    int i, rc;

    /* 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) {

        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) {

        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)

        return EE_UNSUPPORTED;

    /* Check if the ELF image starts on a page boundary */

    if (ALIGN_UP((uintptr_t)header, PAGE_SIZE) != (uintptr_t)header)

        return EE_UNSUPPORTED;

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

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

        elf_segment_header_t *seghdr;

        seghdr = &((elf_segment_header_t *)(((uint8_t *) header) +

            header->e_phoff))[i];

        rc = segment_header(seghdr, header, as);

        if (rc != EE_OK)

            return rc;

    }

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

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

        elf_section_header_t *sechdr;

        sechdr = &((elf_section_header_t *)(((uint8_t *) header) +

            header->e_shoff))[i];

        rc = section_header(sechdr, header, as);

        if (rc != EE_OK)

            return rc;

    }

    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.

 * @param as Address space into wich the ELF is being loaded.

 *

 * @return EE_OK on success, error code otherwise.

 */

static int segment_header(elf_segment_header_t *entry, elf_header_t *elf,

    as_t *as)

{

    switch (entry->p_type) {

    case PT_NULL:

    case PT_PHDR:

        break;

    case PT_LOAD:

        return load_segment(entry, elf, as);

        break;

    case PT_DYNAMIC:

    case PT_INTERP:

    case PT_SHLIB:

    case PT_NOTE:

    case PT_LOPROC:

    case PT_HIPROC:

    default:

        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.

 * @param as Address space into wich the ELF is being loaded.

 *

 * @return EE_OK on success, error code otherwise.

 */

int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)

{

    as_area_t *a;

    int flags = 0;

    mem_backend_data_t backend_data;

    uintptr_t base;

    size_t mem_sz;

    backend_data.elf = elf;

    backend_data.segment = entry;

    if (entry->p_align > 1) {

        if ((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;

    /*

     * Align vaddr down, inserting a little "gap" at the beginning.

     * Adjust area size, so that its end remains in place.

     */

    base = ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE);

    mem_sz = entry->p_memsz + (entry->p_vaddr - base);

    a = as_area_create(as, flags, mem_sz, base,

        AS_AREA_ATTR_NONE, &elf_backend, &backend_data);

    if (!a)

        return EE_MEMORY;

    /*

     * The segment will be mapped on demand by elf_page_fault().

     */

    return EE_OK;

}

/** Process section header.

 *

 * @param entry Segment header.

 * @param elf ELF header.

 * @param as Address space into wich the ELF is being loaded.

 *

 * @return EE_OK on success, error code otherwise.

 */

static int section_header(elf_section_header_t *entry, elf_header_t *elf,

    as_t *as)

{

    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;

    default:

        break;

    }

    return EE_OK;

}

/** @}

 */