flatload.c

xen虚拟机源代码安装包

/****************************************************************************/
/*
 *  QEMU bFLT binary loader.  Based on linux/fs/binfmt_flat.c
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *      Copyright (C) 2006 CodeSourcery.
 *	Copyright (C) 2000-2003 David McCullough <[e-mail]>
 *	Copyright (C) 2002 Greg Ungerer <[e-mail]>
 *	Copyright (C) 2002 SnapGear, by Paul Dale <[e-mail]>
 *	Copyright (C) 2000, 2001 Lineo, by David McCullough <[e-mail]>
 *  based heavily on:
 *
 *  linux/fs/binfmt_aout.c:
 *      Copyright (C) 1991, 1992, 1996  Linus Torvalds
 *  linux/fs/binfmt_flat.c for 2.0 kernel
 *	    Copyright (C) 1998  Kenneth Albanowski <[e-mail]>
 *	JAN/99 -- coded full program relocation ([e-mail])
 */

/* ??? ZFLAT and shared library support is currently disabled.  */

/****************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/mman.h>
#include <unistd.h>

#include "qemu.h"
#include "flat.h"

//#define DEBUG

#ifdef DEBUG
#define	DBG_FLT(a...)	printf(a)
#else
#define	DBG_FLT(a...)
#endif

#define flat_reloc_valid(reloc, size)             ((reloc) <= (size))
#define flat_old_ram_flag(flag)                   (flag)
#ifdef TARGET_WORDS_BIGENDIAN
#define flat_get_relocate_addr(relval)            (relval)
#else
#define flat_get_relocate_addr(relval)            bswap32(relval)
#endif

#define RELOC_FAILED 0xff00ff01		/* Relocation incorrect somewhere */
#define UNLOADED_LIB 0x7ff000ff		/* Placeholder for unused library */

struct lib_info {
    abi_ulong start_code;       /* Start of text segment */
    abi_ulong start_data;       /* Start of data segment */
    abi_ulong end_data;         /* Start of bss section */
    abi_ulong start_brk;        /* End of data segment */
    abi_ulong text_len;	        /* Length of text segment */
    abi_ulong entry;	        /* Start address for this module */
    abi_ulong build_date;       /* When this one was compiled */
    short loaded;		/* Has this library been loaded? */
};

#ifdef CONFIG_BINFMT_SHARED_FLAT
static int load_flat_shared_library(int id, struct lib_info *p);
#endif

struct linux_binprm;

#define ntohl(x) be32_to_cpu(x)

/****************************************************************************/
/*
 * create_flat_tables() parses the env- and arg-strings in new user
 * memory and creates the pointer tables from them, and puts their
 * addresses on the "stack", returning the new stack pointer value.
 */

/* Push a block of strings onto the guest stack.  */
static abi_ulong copy_strings(abi_ulong p, int n, char **s)
{
    int len;

    while (n-- > 0) {
        len = strlen(s[n]) + 1;
        p -= len;
        memcpy_to_target(p, s[n], len);
    }

    return p;
}

int target_pread(int fd, abi_ulong ptr, abi_ulong len,
                 abi_ulong offset)
{
    void *buf;
    int ret;

    buf = lock_user(VERIFY_WRITE, ptr, len, 0);
    ret = pread(fd, buf, len, offset);
    unlock_user(buf, ptr, len);
    return ret;
}
/****************************************************************************/

#ifdef CONFIG_BINFMT_ZFLAT

#include <linux/zlib.h>

#define LBUFSIZE	4000

/* gzip flag byte */
#define ASCII_FLAG   0x01 /* bit 0 set: file probably ASCII text */
#define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
#define EXTRA_FIELD  0x04 /* bit 2 set: extra field present */
#define ORIG_NAME    0x08 /* bit 3 set: original file name present */
#define COMMENT      0x10 /* bit 4 set: file comment present */
#define ENCRYPTED    0x20 /* bit 5 set: file is encrypted */
#define RESERVED     0xC0 /* bit 6,7:   reserved */

static int decompress_exec(
	struct linux_binprm *bprm,
	unsigned long offset,
	char *dst,
	long len,
	int fd)
{
	unsigned char *buf;
	z_stream strm;
	loff_t fpos;
	int ret, retval;

	DBG_FLT("decompress_exec(offset=%x,buf=%x,len=%x)\n",(int)offset, (int)dst, (int)len);

	memset(&strm, 0, sizeof(strm));
	strm.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
	if (strm.workspace == NULL) {
		DBG_FLT("binfmt_flat: no memory for decompress workspace\n");
		return -ENOMEM;
	}
	buf = kmalloc(LBUFSIZE, GFP_KERNEL);
	if (buf == NULL) {
		DBG_FLT("binfmt_flat: no memory for read buffer\n");
		retval = -ENOMEM;
		goto out_free;
	}

	/* Read in first chunk of data and parse gzip header. */
	fpos = offset;
	ret = bprm->file->f_op->read(bprm->file, buf, LBUFSIZE, &fpos);

	strm.next_in = buf;
	strm.avail_in = ret;
	strm.total_in = 0;

	retval = -ENOEXEC;

	/* Check minimum size -- gzip header */
	if (ret < 10) {
		DBG_FLT("binfmt_flat: file too small?\n");
		goto out_free_buf;
	}

	/* Check gzip magic number */
	if ((buf[0] != 037) || ((buf[1] != 0213) && (buf[1] != 0236))) {
		DBG_FLT("binfmt_flat: unknown compression magic?\n");
		goto out_free_buf;
	}

	/* Check gzip method */
	if (buf[2] != 8) {
		DBG_FLT("binfmt_flat: unknown compression method?\n");
		goto out_free_buf;
	}
	/* Check gzip flags */
	if ((buf[3] & ENCRYPTED) || (buf[3] & CONTINUATION) ||
	    (buf[3] & RESERVED)) {
		DBG_FLT("binfmt_flat: unknown flags?\n");
		goto out_free_buf;
	}

	ret = 10;
	if (buf[3] & EXTRA_FIELD) {
		ret += 2 + buf[10] + (buf[11] << 8);
		if (unlikely(LBUFSIZE == ret)) {
			DBG_FLT("binfmt_flat: buffer overflow (EXTRA)?\n");
			goto out_free_buf;
		}
	}
	if (buf[3] & ORIG_NAME) {
		for (; ret < LBUFSIZE && (buf[ret] != 0); ret++)
			;
		if (unlikely(LBUFSIZE == ret)) {
			DBG_FLT("binfmt_flat: buffer overflow (ORIG_NAME)?\n");
			goto out_free_buf;
		}
	}
	if (buf[3] & COMMENT) {
		for (;  ret < LBUFSIZE && (buf[ret] != 0); ret++)
			;
		if (unlikely(LBUFSIZE == ret)) {
			DBG_FLT("binfmt_flat: buffer overflow (COMMENT)?\n");
			goto out_free_buf;
		}
	}

	strm.next_in += ret;
	strm.avail_in -= ret;

	strm.next_out = dst;
	strm.avail_out = len;
	strm.total_out = 0;

	if (zlib_inflateInit2(&strm, -MAX_WBITS) != Z_OK) {
		DBG_FLT("binfmt_flat: zlib init failed?\n");
		goto out_free_buf;
	}

	while ((ret = zlib_inflate(&strm, Z_NO_FLUSH)) == Z_OK) {
		ret = bprm->file->f_op->read(bprm->file, buf, LBUFSIZE, &fpos);
		if (ret <= 0)
			break;
		if (ret >= (unsigned long) -4096)
			break;
		len -= ret;

		strm.next_in = buf;
		strm.avail_in = ret;
		strm.total_in = 0;
	}

	if (ret < 0) {
		DBG_FLT("binfmt_flat: decompression failed (%d), %s\n",
			ret, strm.msg);
		goto out_zlib;
	}

	retval = 0;
out_zlib:
	zlib_inflateEnd(&strm);
out_free_buf:
	kfree(buf);
out_free:
	kfree(strm.workspace);
out:
	return retval;
}

#endif /* CONFIG_BINFMT_ZFLAT */

/****************************************************************************/

static abi_ulong
calc_reloc(abi_ulong r, struct lib_info *p, int curid, int internalp)
{
    abi_ulong addr;
    int id;
    abi_ulong start_brk;
    abi_ulong start_data;
    abi_ulong text_len;
    abi_ulong start_code;

#ifdef CONFIG_BINFMT_SHARED_FLAT
#error needs checking
    if (r == 0)
        id = curid;	/* Relocs of 0 are always self referring */
    else {
        id = (r >> 24) & 0xff;	/* Find ID for this reloc */
        r &= 0x00ffffff;	/* Trim ID off here */
    }
    if (id >= MAX_SHARED_LIBS) {
        fprintf(stderr, "BINFMT_FLAT: reference 0x%x to shared library %d\n",
                (unsigned) r, id);
        goto failed;
    }
    if (curid != id) {
        if (internalp) {
            fprintf(stderr, "BINFMT_FLAT: reloc address 0x%x not "
                    "in same module (%d != %d)\n",
                    (unsigned) r, curid, id);
            goto failed;
        } else if ( ! p[id].loaded &&
                    load_flat_shared_library(id, p) > (unsigned long) -4096) {
            fprintf(stderr, "BINFMT_FLAT: failed to load library %d\n", id);
            goto failed;
        }
        /* Check versioning information (i.e. time stamps) */
        if (p[id].build_date && p[curid].build_date
            && p[curid].build_date < p[id].build_date) {
            fprintf(stderr, "BINFMT_FLAT: library %d is younger than %d\n",
                    id, curid);
            goto failed;
        }
    }
#else
    id = 0;
#endif

    start_brk = p[id].start_brk;
    start_data = p[id].start_data;
    start_code = p[id].start_code;
    text_len = p[id].text_len;

    if (!flat_reloc_valid(r, start_brk - start_data + text_len)) {
        fprintf(stderr, "BINFMT_FLAT: reloc outside program 0x%x "
                "(0 - 0x%x/0x%x)\n",
               (int) r,(int)(start_brk-start_code),(int)text_len);
        goto failed;
    }

    if (r < text_len)			/* In text segment */
        addr = r + start_code;
    else					/* In data segment */
        addr = r - text_len + start_data;

    /* Range checked already above so doing the range tests is redundant...*/
    return(addr);

failed:
    abort();
    return RELOC_FAILED;
}

/****************************************************************************/

/* ??? This does not handle endianness correctly.  */
void old_reloc(struct lib_info *libinfo, uint32_t rl)
{
#ifdef DEBUG
	char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
#endif
	uint32_t *ptr;
        uint32_t offset;
        int reloc_type;

        offset = rl & 0x3fffffff;
        reloc_type = rl >> 30;
        /* ??? How to handle this?  */
#if defined(CONFIG_COLDFIRE)
	ptr = (uint32_t *) (libinfo->start_code + offset);
#else
	ptr = (uint32_t *) (libinfo->start_data + offset);
#endif

#ifdef DEBUG
	fprintf(stderr, "Relocation of variable at DATASEG+%x "
		"(address %p, currently %x) into segment %s\n",
		offset, ptr, (int)*ptr, segment[reloc_type]);
#endif

	switch (reloc_type) {
	case OLD_FLAT_RELOC_TYPE_TEXT:
		*ptr += libinfo->start_code;
		break;
	case OLD_FLAT_RELOC_TYPE_DATA:
		*ptr += libinfo->start_data;
		break;
	case OLD_FLAT_RELOC_TYPE_BSS:
		*ptr += libinfo->end_data;
		break;
	default:
		fprintf(stderr, "BINFMT_FLAT: Unknown relocation type=%x\n",
                        reloc_type);
		break;
	}
	DBG_FLT("Relocation became %x\n", (int)*ptr);
}

/****************************************************************************/

static int load_flat_file(struct linux_binprm * bprm,
		struct lib_info *libinfo, int id, abi_ulong *extra_stack)
{
    struct flat_hdr * hdr;
    abi_ulong textpos = 0, datapos = 0, result;
    abi_ulong realdatastart = 0;
    abi_ulong text_len, data_len, bss_len, stack_len, flags;
    abi_ulong memp = 0; /* for finding the brk area */
    abi_ulong extra;
    abi_ulong reloc = 0, rp;
    int i, rev, relocs = 0;
    abi_ulong fpos;
    abi_ulong start_code, end_code;
    abi_ulong indx_len;

    hdr = ((struct flat_hdr *) bprm->buf);		/* exec-header */

    text_len  = ntohl(hdr->data_start);
    data_len  = ntohl(hdr->data_end) - ntohl(hdr->data_start);
    bss_len   = ntohl(hdr->bss_end) - ntohl(hdr->data_end);
    stack_len = ntohl(hdr->stack_size);
    if (extra_stack) {
        stack_len += *extra_stack;
        *extra_stack = stack_len;
    }
    relocs    = ntohl(hdr->reloc_count);