loader.c

qemu虚拟机代码

/*
 * QEMU Executable loader
 * 
 * Copyright (c) 2006 Fabrice Bellard
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include "vl.h"
#include "disas.h"

/* return the size or -1 if error */
int get_image_size(const char *filename)
{
    int fd, size;
    fd = open(filename, O_RDONLY | O_BINARY);
    if (fd < 0)
        return -1;
    size = lseek(fd, 0, SEEK_END);
    close(fd);
    return size;
}

/* return the size or -1 if error */
int load_image(const char *filename, uint8_t *addr)
{
    int fd, size;
    fd = open(filename, O_RDONLY | O_BINARY);
    if (fd < 0)
        return -1;
    size = lseek(fd, 0, SEEK_END);
    lseek(fd, 0, SEEK_SET);
    if (read(fd, addr, size) != size) {
        close(fd);
        return -1;
    }
    close(fd);
    return size;
}

/* A.OUT loader */

struct exec
{
  uint32_t a_info;   /* Use macros N_MAGIC, etc for access */
  uint32_t a_text;   /* length of text, in bytes */
  uint32_t a_data;   /* length of data, in bytes */
  uint32_t a_bss;    /* length of uninitialized data area, in bytes */
  uint32_t a_syms;   /* length of symbol table data in file, in bytes */
  uint32_t a_entry;  /* start address */
  uint32_t a_trsize; /* length of relocation info for text, in bytes */
  uint32_t a_drsize; /* length of relocation info for data, in bytes */
};

#ifdef BSWAP_NEEDED
static void bswap_ahdr(struct exec *e)
{
    bswap32s(&e->a_info);
    bswap32s(&e->a_text);
    bswap32s(&e->a_data);
    bswap32s(&e->a_bss);
    bswap32s(&e->a_syms);
    bswap32s(&e->a_entry);
    bswap32s(&e->a_trsize);
    bswap32s(&e->a_drsize);
}
#else
#define bswap_ahdr(x) do { } while (0)
#endif

#define N_MAGIC(exec) ((exec).a_info & 0xffff)
#define OMAGIC 0407
#define NMAGIC 0410
#define ZMAGIC 0413
#define QMAGIC 0314
#define _N_HDROFF(x) (1024 - sizeof (struct exec))
#define N_TXTOFF(x)							\
    (N_MAGIC(x) == ZMAGIC ? _N_HDROFF((x)) + sizeof (struct exec) :	\
     (N_MAGIC(x) == QMAGIC ? 0 : sizeof (struct exec)))
#define N_TXTADDR(x) (N_MAGIC(x) == QMAGIC ? TARGET_PAGE_SIZE : 0)
#define N_DATOFF(x) (N_TXTOFF(x) + (x).a_text)
#define _N_SEGMENT_ROUND(x) (((x) + TARGET_PAGE_SIZE - 1) & ~(TARGET_PAGE_SIZE - 1))

#define _N_TXTENDADDR(x) (N_TXTADDR(x)+(x).a_text)

#define N_DATADDR(x) \
    (N_MAGIC(x)==OMAGIC? (_N_TXTENDADDR(x)) \
     : (_N_SEGMENT_ROUND (_N_TXTENDADDR(x))))


int load_aout(const char *filename, uint8_t *addr)
{
    int fd, size, ret;
    struct exec e;
    uint32_t magic;

    fd = open(filename, O_RDONLY | O_BINARY);
    if (fd < 0)
        return -1;

    size = read(fd, &e, sizeof(e));
    if (size < 0)
        goto fail;

    bswap_ahdr(&e);

    magic = N_MAGIC(e);
    switch (magic) {
    case ZMAGIC:
    case QMAGIC:
    case OMAGIC:
	lseek(fd, N_TXTOFF(e), SEEK_SET);
	size = read(fd, addr, e.a_text + e.a_data);
	if (size < 0)
	    goto fail;
	break;
    case NMAGIC:
	lseek(fd, N_TXTOFF(e), SEEK_SET);
	size = read(fd, addr, e.a_text);
	if (size < 0)
	    goto fail;
	ret = read(fd, addr + N_DATADDR(e), e.a_data);
	if (ret < 0)
	    goto fail;
	size += ret;
	break;
    default:
	goto fail;
    }
    close(fd);
    return size;
 fail:
    close(fd);
    return -1;
}

/* ELF loader */

static void *load_at(int fd, int offset, int size)
{
    void *ptr;
    if (lseek(fd, offset, SEEK_SET) < 0)
        return NULL;
    ptr = qemu_malloc(size);
    if (!ptr)
        return NULL;
    if (read(fd, ptr, size) != size) {
        qemu_free(ptr);
        return NULL;
    }
    return ptr;
}


#define ELF_CLASS   ELFCLASS32
#include "elf.h"

#define SZ		32
#define elf_word        uint32_t
#define bswapSZs	bswap32s
#include "elf_ops.h"

#undef elfhdr
#undef elf_phdr
#undef elf_shdr
#undef elf_sym
#undef elf_note
#undef elf_word
#undef bswapSZs
#undef SZ
#define elfhdr		elf64_hdr
#define elf_phdr	elf64_phdr
#define elf_note	elf64_note
#define elf_shdr	elf64_shdr
#define elf_sym		elf64_sym
#define elf_word        uint64_t
#define bswapSZs	bswap64s
#define SZ		64
#include "elf_ops.h"

/* return < 0 if error, otherwise the number of bytes loaded in memory */
int load_elf(const char *filename, int64_t virt_to_phys_addend,
             uint64_t *pentry)
{
    int fd, data_order, must_swab, ret;
    uint8_t e_ident[EI_NIDENT];

    fd = open(filename, O_RDONLY);
    if (fd < 0) {
        perror(filename);
        return -1;
    }
    if (read(fd, e_ident, sizeof(e_ident)) != sizeof(e_ident))
        goto fail;
    if (e_ident[0] != ELFMAG0 ||
        e_ident[1] != ELFMAG1 ||
        e_ident[2] != ELFMAG2 ||
        e_ident[3] != ELFMAG3)
        goto fail;
#ifdef WORDS_BIGENDIAN
    data_order = ELFDATA2MSB;
#else
    data_order = ELFDATA2LSB;
#endif
    must_swab = data_order != e_ident[EI_DATA];
    
    lseek(fd, 0, SEEK_SET);
    if (e_ident[EI_CLASS] == ELFCLASS64) {
        ret = load_elf64(fd, virt_to_phys_addend, must_swab, pentry);
    } else {
        ret = load_elf32(fd, virt_to_phys_addend, must_swab, pentry);
    }

    close(fd);
    return ret;

 fail:
    close(fd);
    return -1;
}