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854 bondari 1
/*
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 * Copyright (C) 2006 Sergey Bondari
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#include <elf.h>
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#include <debug.h>
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#include <arch/types.h>
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#include <typedefs.h>
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#include <mm/as.h>
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#include <mm/frame.h>
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#include <print.h>
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#include <align.h>
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static char *error_codes[] = {
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    "no error",
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    "invalid image",
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    "address space error",
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    "incompatible image",
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    "unsupported image type",
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    "irrecoverable error"
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};
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static int program_header_entry(elf_header_t *header, elf_ph_entry_t *entry, as_t *as);
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static int load_segment(elf_header_t *header, elf_ph_entry_t *entry, as_t *as);
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/** ELF loader
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 *
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 * @param header Pointer to ELF header in memory
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 * @param as Created and properly mapped address space
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 * @return EE_OK on success
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 */
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int elf_load(elf_header_t *header, as_t * as)
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{
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    int i, rc;
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    /* Identify ELF */
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    if (header->e_ident[EI_MAG0] != ELFMAG0 || header->e_ident[EI_MAG1] != ELFMAG1 ||
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        header->e_ident[EI_MAG2] != ELFMAG2 || header->e_ident[EI_MAG3] != ELFMAG3) {
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        return EE_INVALID;
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    }
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    /* Identify ELF compatibility */
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    if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING || header->e_machine != ELF_MACHINE ||
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        header->e_ident[EI_VERSION] != EV_CURRENT || header->e_version != EV_CURRENT ||
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        header->e_ident[EI_CLASS] != ELF_CLASS) {
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        return EE_INCOMPATIBLE;
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    }
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    if (header->e_phentsize != sizeof(elf_ph_entry_t))
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        return EE_INCOMPATIBLE;
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    /* Check if the object type is supported. */
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    if (header->e_type != ET_EXEC)
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        return EE_UNSUPPORTED;
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    /* Walk through all program header entries and process them. */
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    for (i = 0; i < header->e_phnum; i++) {
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        rc = program_header_entry(header, &((elf_ph_entry_t *)(((__u8 *) header) + header->e_phoff))[i], as);
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        if (rc != EE_OK)
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            return rc;
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    }
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    return EE_OK;
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}
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/** Print error message according to error code.
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 *
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 * @param rc Return code returned by elf_load().
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 *
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 * @return NULL terminated description of error.
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 */
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char *elf_error(int rc)
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{
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    ASSERT(rc < sizeof(error_codes)/sizeof(char *));
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    return error_codes[rc];
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}
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/** Process program header entry.
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 *
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 * @param entry Program header entry.
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 * @param as Address space into wich the ELF is being loaded.
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 *
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 * @return EE_OK on success, error code otherwise.
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 */
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static int program_header_entry(elf_header_t *header, elf_ph_entry_t *entry, as_t *as)
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{
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    switch (entry->p_type) {
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        case PT_NULL:
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        case PT_PHDR:
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        break;
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        case PT_LOAD:
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        return load_segment(header, entry, as);
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        break;
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        case PT_DYNAMIC:
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        case PT_INTERP:
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        case PT_SHLIB:
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        case PT_NOTE:
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        case PT_LOPROC:
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        case PT_HIPROC:
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        default:
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        return EE_UNSUPPORTED;
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        break;
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    }
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    return EE_OK;
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}
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/** Load segment described by program header entry.
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 *
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 * @param entry Program header entry describing segment to be loaded.
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 * @parma as Address space into wich the ELF is being loaded.
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 *
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 * @return EE_OK on success, error code otherwise.
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 */
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int load_segment(elf_header_t *header, elf_ph_entry_t *entry, as_t *as)
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{
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    as_area_t *a;
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    int i, type = 0;
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    if (entry->p_align > 1) {
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        if ((entry->p_offset % entry->p_align) != (entry->p_vaddr % entry->p_align)) {
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            return EE_INVALID;
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        }
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    }
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    /*
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     * Check if the segment doesn't interfere with kernel address space.
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     */
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    if (entry->p_vaddr + ALIGN_UP(entry->p_memsz, PAGE_SIZE) >= USER_ADDRESS_SPACE_END)
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        return EE_MEMORY;
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    if (entry->p_flags & PF_X) {
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        type = AS_AREA_TEXT;
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    } else if (entry->p_flags & PF_W) {
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        type = AS_AREA_DATA;
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    } else {
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        return EE_UNSUPPORTED;
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    }
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    a = as_area_create(as, AS_AREA_TEXT, SIZE2FRAMES(entry->p_memsz), entry->p_vaddr);
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    if (!a)
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        return EE_IRRECOVERABLE;
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    for (i = 0; i < SIZE2FRAMES(entry->p_filesz); i++) {
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        as_set_mapping(as, entry->p_vaddr + i*PAGE_SIZE, KA2PA(((__address) header) + entry->p_offset + i*PAGE_SIZE));
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    }
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    return EE_OK;
854 bondari 173
}