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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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1264 jermar 29 
/**
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 * @file    elf.c
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 * @brief   Kernel ELF loader.
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 */
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910 bondari 34 
#include <elf.h>
938 jermar 35 
#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>
952 jermar 40 
#include <mm/slab.h>
938 jermar 41 
#include <align.h>
952 jermar 42 
#include <memstr.h>
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#include <macros.h>
854 bondari 44 
 
938 jermar 45 
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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952 jermar 54 
static int segment_header(elf_segment_header_t *entry, elf_header_t *elf, as_t *as);
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static int section_header(elf_section_header_t *entry, elf_header_t *elf, as_t *as);
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static int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as);
938 jermar 57 
 
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/** ELF loader
854 bondari 59 
 *
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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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 */
938 jermar 64 
int elf_load(elf_header_t *header, as_t * as)
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{
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    int i, rc;
910 bondari 67 
 
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    /* Identify ELF */
938 jermar 69 
    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) {
910 bondari 71 
        return EE_INVALID;
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    }
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    /* Identify ELF compatibility */
938 jermar 75 
    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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952 jermar 81 
    if (header->e_phentsize != sizeof(elf_segment_header_t))
938 jermar 82 
        return EE_INCOMPATIBLE;
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952 jermar 84 
    if (header->e_shentsize != sizeof(elf_section_header_t))
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        return EE_INCOMPATIBLE;
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938 jermar 87 
    /* Check if the object type is supported. */
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    if (header->e_type != ET_EXEC)
910 bondari 89 
        return EE_UNSUPPORTED;
938 jermar 90 
 
952 jermar 91 
    /* Walk through all segment headers and process them. */
938 jermar 92 
    for (i = 0; i < header->e_phnum; i++) {
952 jermar 93 
        rc = segment_header(&((elf_segment_header_t *)(((__u8 *) header) + header->e_phoff))[i], header, as);
938 jermar 94 
        if (rc != EE_OK)
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            return rc;
910 bondari 96 
    }
938 jermar 97 
 
952 jermar 98 
    /* Inspect all section headers and proccess them. */
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    for (i = 0; i < header->e_shnum; i++) {
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        rc = section_header(&((elf_section_header_t *)(((__u8 *) header) + header->e_shoff))[i], header, as);
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        if (rc != EE_OK)
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            return rc;
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    }
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938 jermar 105 
    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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952 jermar 121 
/** Process segment header.
938 jermar 122 
 *
952 jermar 123 
 * @param entry Segment header.
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 * @param elf ELF header.
938 jermar 125 
 * @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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 */
952 jermar 129 
static int segment_header(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
938 jermar 130 
{
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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:
952 jermar 136 
        return load_segment(entry, elf, as);
938 jermar 137 
        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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}
150 
 
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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.
952 jermar 154 
 * @param elf ELF header.
1248 jermar 155 
 * @param as Address space into wich the ELF is being loaded.
938 jermar 156 
 *
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 * @return EE_OK on success, error code otherwise.
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 */
952 jermar 159 
int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
938 jermar 160 
{
161 
    as_area_t *a;
1026 jermar 162 
    int i, flags = 0;
952 jermar 163 
    size_t segment_size;
164 
    __u8 *segment;
938 jermar 165 
 
166 
    if (entry->p_align > 1) {
167 
        if ((entry->p_offset % entry->p_align) != (entry->p_vaddr % entry->p_align)) {
168 
            return EE_INVALID;
169 
        }
170 
    }
171 
 
1026 jermar 172 
    if (entry->p_flags & PF_X)
173 
        flags |= AS_AREA_EXEC;
174 
    if (entry->p_flags & PF_W)
175 
        flags |= AS_AREA_WRITE;
176 
    if (entry->p_flags & PF_R)
177 
        flags |= AS_AREA_READ;
910 bondari 178 
 
952 jermar 179 
    /*
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     * Check if the virtual address starts on page boundary.
181 
     */
182 
    if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr)
183 
        return EE_UNSUPPORTED;
184 
 
185 
    segment_size = ALIGN_UP(max(entry->p_filesz, entry->p_memsz), PAGE_SIZE);
973 palkovsky 186 
    if ((entry->p_flags & PF_W)) {
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        /* If writable, copy data (should be COW in the future) */
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        segment = malloc(segment_size, 0);
952 jermar 189 
        memsetb((__address) (segment + entry->p_filesz), segment_size - entry->p_filesz, 0);
973 palkovsky 190 
        memcpy(segment, (void *) (((__address) elf) + entry->p_offset), entry->p_filesz);
191 
    } else /* Map identically original data */
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        segment = ((void *) elf) + entry->p_offset;
952 jermar 193 
 
1239 jermar 194 
    a = as_area_create(as, flags, entry->p_memsz, entry->p_vaddr, AS_AREA_ATTR_NONE);
938 jermar 195 
    if (!a)
1070 jermar 196 
        return EE_MEMORY;
938 jermar 197 
 
198 
    for (i = 0; i < SIZE2FRAMES(entry->p_filesz); i++) {
952 jermar 199 
        as_set_mapping(as, entry->p_vaddr + i*PAGE_SIZE, KA2PA(((__address) segment) + i*PAGE_SIZE));
938 jermar 200 
    }
201 
 
202 
    return EE_OK;
854 bondari 203 
}
952 jermar 204 
 
205 
/** Process section header.
206 
 *
207 
 * @param entry Segment header.
208 
 * @param elf ELF header.
209 
 * @param as Address space into wich the ELF is being loaded.
210 
 *
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 * @return EE_OK on success, error code otherwise.
212 
 */
213 
static int section_header(elf_section_header_t *entry, elf_header_t *elf, as_t *as)
214 
{
215 
    switch (entry->sh_type) {
216 
        default:
217 
        break;
218 
    }
219 
 
220 
    return EE_OK;
221 
}