binfmt_flat.c

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/****************************************************************************/
/*
 *  linux/fs/binfmt_flat.c
 *
 *  Copyright (C) 2000-2003 David McCullough <[email protected]>
 *  Copyright (C) 2002 Greg Ungerer <[email protected]>
 *  Copyright (C) 2002 SnapGear, by Paul Dale <[email protected]>
 *  Copyright (C) 2000, 2001 Lineo, by David McCullough <[email protected]>
 *  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 <[email protected]>
 *  JAN/99 -- coded full program relocation ([email protected])
 */

#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/slab.h>
#include <linux/binfmts.h>
#include <linux/personality.h>
#include <linux/init.h>
#include <linux/flat.h>
#include <linux/syscalls.h>

#include <asm/byteorder.h>
#include <asm/uaccess.h>
#include <asm/unaligned.h>
#include <asm/cacheflush.h>
#include <asm/page.h>

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

#if 0
#define DEBUG 1
#endif

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

/*
 * User data (data section and bss) needs to be aligned.
 * We pick 0x20 here because it is the max value elf2flt has always
 * used in producing FLAT files, and because it seems to be large
 * enough to make all the gcc alignment related tests happy.
 */
#define FLAT_DATA_ALIGN (0x20)

/*
 * User data (stack) also needs to be aligned.
 * Here we can be a bit looser than the data sections since this
 * needs to only meet arch ABI requirements.
 */
#define FLAT_STACK_ALIGN    max_t(unsigned long, sizeof(void *), ARCH_SLAB_MINALIGN)

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

struct lib_info {
    struct {
        unsigned long start_code;       /* Start of text segment */
        unsigned long start_data;       /* Start of data segment */
        unsigned long start_brk;        /* End of data segment */
        unsigned long text_len;         /* Length of text segment */
        unsigned long entry;            /* Start address for this module */
        unsigned long build_date;       /* When this one was compiled */
        short loaded;               /* Has this library been loaded? */
    } lib_list[MAX_SHARED_LIBS];
};

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

static int load_flat_binary(struct linux_binprm *, struct pt_regs * regs);
static int flat_core_dump(struct coredump_params *cprm);

static struct linux_binfmt flat_format = {
    .module     = THIS_MODULE,
    .load_binary    = load_flat_binary,
    .core_dump  = flat_core_dump,
    .min_coredump   = PAGE_SIZE
};

/****************************************************************************/
/*
 * Routine writes a core dump image in the current directory.
 * Currently only a stub-function.
 */

static int flat_core_dump(struct coredump_params *cprm)
{
    printk("Process %s:%d received signr %d and should have core dumped\n",
            current->comm, current->pid, (int) cprm->siginfo->si_signo);
    return(1);
}

/****************************************************************************/
/*
 * 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.
 */

static unsigned long create_flat_tables(
    unsigned long pp,
    struct linux_binprm * bprm)
{
    unsigned long *argv,*envp;
    unsigned long * sp;
    char * p = (char*)pp;
    int argc = bprm->argc;
    int envc = bprm->envc;
    char uninitialized_var(dummy);

    sp = (unsigned long *)p;
    sp -= (envc + argc + 2) + 1 + (flat_argvp_envp_on_stack() ? 2 : 0);
    sp = (unsigned long *) ((unsigned long)sp & -FLAT_STACK_ALIGN);
    argv = sp + 1 + (flat_argvp_envp_on_stack() ? 2 : 0);
    envp = argv + (argc + 1);

    if (flat_argvp_envp_on_stack()) {
        put_user((unsigned long) envp, sp + 2);
        put_user((unsigned long) argv, sp + 1);
    }

    put_user(argc, sp);
    current->mm->arg_start = (unsigned long) p;
    while (argc-->0) {
        put_user((unsigned long) p, argv++);
        do {
            get_user(dummy, p); p++;
        } while (dummy);
    }
    put_user((unsigned long) NULL, argv);
    current->mm->arg_end = current->mm->env_start = (unsigned long) p;
    while (envc-->0) {
        put_user((unsigned long)p, envp); envp++;
        do {
            get_user(dummy, p); p++;
        } while (dummy);
    }
    put_user((unsigned long) NULL, envp);
    current->mm->env_end = (unsigned long) p;
    return (unsigned long)sp;
}

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

#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) {
        while (ret < LBUFSIZE && buf[ret++] != 0)
            ;
        if (unlikely(LBUFSIZE == ret)) {
            DBG_FLT("binfmt_flat: buffer overflow (ORIG_NAME)?\n");
            goto out_free_buf;
        }
    }
    if (buf[3] & COMMENT) {
        while (ret < LBUFSIZE && buf[ret++] != 0)
            ;
        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;
        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);
    return retval;
}

#endif /* CONFIG_BINFMT_ZFLAT */

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

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

#ifdef CONFIG_BINFMT_SHARED_FLAT
    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) {
        printk("BINFMT_FLAT: reference 0x%x to shared library %d",
                (unsigned) r, id);
        goto failed;
    }
    if (curid != id) {
        if (internalp) {
            printk("BINFMT_FLAT: reloc address 0x%x not in same module "
                    "(%d != %d)", (unsigned) r, curid, id);
            goto failed;
        } else if ( ! p->lib_list[id].loaded &&
                IS_ERR_VALUE(load_flat_shared_library(id, p))) {
            printk("BINFMT_FLAT: failed to load library %d", id);
            goto failed;
        }
        /* Check versioning information (i.e. time stamps) */
        if (p->lib_list[id].build_date && p->lib_list[curid].build_date &&
                p->lib_list[curid].build_date < p->lib_list[id].build_date) {
            printk("BINFMT_FLAT: library %d is younger than %d", id, curid);
            goto failed;
        }
    }
#else
    id = 0;
#endif

    start_brk = p->lib_list[id].start_brk;
    start_data = p->lib_list[id].start_data;
    start_code = p->lib_list[id].start_code;
    text_len = p->lib_list[id].text_len;

    if (!flat_reloc_valid(r, start_brk - start_data + text_len)) {
        printk("BINFMT_FLAT: reloc outside program 0x%x (0 - 0x%x/0x%x)",
               (int) r,(int)(start_brk-start_data+text_len),(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:
    printk(", killing %s!\n", current->comm);
    send_sig(SIGSEGV, current, 0);

    return RELOC_FAILED;
}

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

void old_reloc(unsigned long rl)
{
#ifdef DEBUG
    char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
#endif
    flat_v2_reloc_t r;
    unsigned long *ptr;
    
    r.value = rl;
#if defined(CONFIG_COLDFIRE)
    ptr = (unsigned long *) (current->mm->start_code + r.reloc.offset);
#else
    ptr = (unsigned long *) (current->mm->start_data + r.reloc.offset);
#endif

#ifdef DEBUG
    printk("Relocation of variable at DATASEG+%x "
        "(address %p, currently %x) into segment %s\n",
        r.reloc.offset, ptr, (int)*ptr, segment[r.reloc.type]);
#endif
    
    switch (r.reloc.type) {
    case OLD_FLAT_RELOC_TYPE_TEXT:
        *ptr += current->mm->start_code;
        break;
    case OLD_FLAT_RELOC_TYPE_DATA:
        *ptr += current->mm->start_data;
        break;
    case OLD_FLAT_RELOC_TYPE_BSS:
        *ptr += current->mm->end_data;
        break;
    default:
        printk("BINFMT_FLAT: Unknown relocation type=%x\n", r.reloc.type);
        break;
    }

#ifdef DEBUG
    printk("Relocation became %x\n", (int)*ptr);
#endif
}       

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

static int load_flat_file(struct linux_binprm * bprm,
        struct lib_info *libinfo, int id, unsigned long *extra_stack)
{
    struct flat_hdr * hdr;
    unsigned long textpos = 0, datapos = 0, result;
    unsigned long realdatastart = 0;
    unsigned long text_len, data_len, bss_len, stack_len, flags;
    unsigned long len, memp = 0;
    unsigned long memp_size, extra, rlim;
    unsigned long *reloc = 0, *rp;
    struct inode *inode;
    int i, rev, relocs = 0;
    loff_t fpos;
    unsigned long start_code, end_code;
    int ret;

    hdr = ((struct flat_hdr *) bprm->buf);      /* exec-header */
    inode = bprm->file->f_path.dentry->d_inode;

    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);
    flags     = ntohl(hdr->flags);
    rev       = ntohl(hdr->rev);

    if (strncmp(hdr->magic, "bFLT", 4)) {
        /*
         * Previously, here was a printk to tell people
         *   "BINFMT_FLAT: bad header magic".
         * But for the kernel which also use ELF FD-PIC format, this
         * error message is confusing.
         * because a lot of people do not manage to produce good
         */
        ret = -ENOEXEC;
        goto err;
    }

    if (flags & FLAT_FLAG_KTRACE)
        printk("BINFMT_FLAT: Loading file: %s\n", bprm->filename);

    if (rev != FLAT_VERSION && rev != OLD_FLAT_VERSION) {
        printk("BINFMT_FLAT: bad flat file version 0x%x (supported "
            "0x%lx and 0x%lx)\n",
            rev, FLAT_VERSION, OLD_FLAT_VERSION);
        ret = -ENOEXEC;
        goto err;
    }
    
    /* Don't allow old format executables to use shared libraries */
    if (rev == OLD_FLAT_VERSION && id != 0) {
        printk("BINFMT_FLAT: shared libraries are not available before rev 0x%x\n",
                (int) FLAT_VERSION);
        ret = -ENOEXEC;
        goto err;
    }

    /*
     * fix up the flags for the older format,  there were all kinds
     * of endian hacks,  this only works for the simple cases
     */
    if (rev == OLD_FLAT_VERSION && flat_old_ram_flag(flags))
        flags = FLAT_FLAG_RAM;

#ifndef CONFIG_BINFMT_ZFLAT
    if (flags & (FLAT_FLAG_GZIP|FLAT_FLAG_GZDATA)) {
        printk("Support for ZFLAT executables is not enabled.\n");
        ret = -ENOEXEC;
        goto err;
    }
#endif

    /*
     * Check initial limits. This avoids letting people circumvent
     * size limits imposed on them by creating programs with large
     * arrays in the data or bss.
     */
    rlim = rlimit(RLIMIT_DATA);
    if (rlim >= RLIM_INFINITY)
        rlim = ~0;
    if (data_len + bss_len > rlim) {
        ret = -ENOMEM;
        goto err;
    }

    /* Flush all traces of the currently running executable */
    if (id == 0) {
        result = flush_old_exec(bprm);
        if (result) {
            ret = result;
            goto err;
        }

        /* OK, This is the point of no return */
        set_personality(PER_LINUX_32BIT);
        setup_new_exec(bprm);
    }

    /*
     * calculate the extra space we need to map in
     */
    extra = max_t(unsigned long, bss_len + stack_len,
            relocs * sizeof(unsigned long));

    /*
     * there are a couple of cases here,  the separate code/data
     * case,  and then the fully copied to RAM case which lumps
     * it all together.
     */
    if ((flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP)) == 0) {
        /*
         * this should give us a ROM ptr,  but if it doesn't we don't
         * really care
         */
        DBG_FLT("BINFMT_FLAT: ROM mapping of file (we hope)\n");

        textpos = vm_mmap(bprm->file, 0, text_len, PROT_READ|PROT_EXEC,
                  MAP_PRIVATE|MAP_EXECUTABLE, 0);
        if (!textpos || IS_ERR_VALUE(textpos)) {
            if (!textpos)
                textpos = (unsigned long) -ENOMEM;
            printk("Unable to mmap process text, errno %d\n", (int)-textpos);
            ret = textpos;
            goto err;
        }

        len = data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
        len = PAGE_ALIGN(len);
        realdatastart = vm_mmap(0, 0, len,
            PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, 0);

        if (realdatastart == 0 || IS_ERR_VALUE(realdatastart)) {
            if (!realdatastart)
                realdatastart = (unsigned long) -ENOMEM;
            printk("Unable to allocate RAM for process data, errno %d\n",
                    (int)-realdatastart);
            vm_munmap(textpos, text_len);
            ret = realdatastart;
            goto err;
        }
        datapos = ALIGN(realdatastart +
                MAX_SHARED_LIBS * sizeof(unsigned long),
                FLAT_DATA_ALIGN);

        DBG_FLT("BINFMT_FLAT: Allocated data+bss+stack (%d bytes): %x\n",
                (int)(data_len + bss_len + stack_len), (int)datapos);

        fpos = ntohl(hdr->data_start);
#ifdef CONFIG_BINFMT_ZFLAT
        if (flags & FLAT_FLAG_GZDATA) {
            result = decompress_exec(bprm, fpos, (char *) datapos, 
                         data_len + (relocs * sizeof(unsigned long)), 0);
        } else
#endif
        {
            result = bprm->file->f_op->read(bprm->file, (char *) datapos,
                    data_len + (relocs * sizeof(unsigned long)), &fpos);
        }
        if (IS_ERR_VALUE(result)) {
            printk("Unable to read data+bss, errno %d\n", (int)-result);
            vm_munmap(textpos, text_len);
            vm_munmap(realdatastart, len);
            ret = result;
            goto err;
        }

        reloc = (unsigned long *) (datapos+(ntohl(hdr->reloc_start)-text_len));
        memp = realdatastart;
        memp_size = len;
    } else {

        len = text_len + data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
        len = PAGE_ALIGN(len);
        textpos = vm_mmap(0, 0, len,
            PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE, 0);

        if (!textpos || IS_ERR_VALUE(textpos)) {
            if (!textpos)
                textpos = (unsigned long) -ENOMEM;
            printk("Unable to allocate RAM for process text/data, errno %d\n",
                    (int)-textpos);
            ret = textpos;
            goto err;
        }

        realdatastart = textpos + ntohl(hdr->data_start);
        datapos = ALIGN(realdatastart +
                MAX_SHARED_LIBS * sizeof(unsigned long),
                FLAT_DATA_ALIGN);

        reloc = (unsigned long *)
            (datapos + (ntohl(hdr->reloc_start) - text_len));
        memp = textpos;
        memp_size = len;
#ifdef CONFIG_BINFMT_ZFLAT
        /*
         * load it all in and treat it like a RAM load from now on
         */
        if (flags & FLAT_FLAG_GZIP) {
            result = decompress_exec(bprm, sizeof (struct flat_hdr),
                     (((char *) textpos) + sizeof (struct flat_hdr)),
                     (text_len + data_len + (relocs * sizeof(unsigned long))
                          - sizeof (struct flat_hdr)),
                     0);
            memmove((void *) datapos, (void *) realdatastart,
                    data_len + (relocs * sizeof(unsigned long)));
        } else if (flags & FLAT_FLAG_GZDATA) {
            fpos = 0;
            result = bprm->file->f_op->read(bprm->file,
                    (char *) textpos, text_len, &fpos);
            if (!IS_ERR_VALUE(result))
                result = decompress_exec(bprm, text_len, (char *) datapos,
                         data_len + (relocs * sizeof(unsigned long)), 0);
        }
        else
#endif
        {
            fpos = 0;
            result = bprm->file->f_op->read(bprm->file,
                    (char *) textpos, text_len, &fpos);
            if (!IS_ERR_VALUE(result)) {
                fpos = ntohl(hdr->data_start);
                result = bprm->file->f_op->read(bprm->file, (char *) datapos,
                    data_len + (relocs * sizeof(unsigned long)), &fpos);
            }
        }
        if (IS_ERR_VALUE(result)) {
            printk("Unable to read code+data+bss, errno %d\n",(int)-result);
            vm_munmap(textpos, text_len + data_len + extra +
                MAX_SHARED_LIBS * sizeof(unsigned long));
            ret = result;
            goto err;
        }
    }

    if (flags & FLAT_FLAG_KTRACE)
        printk("Mapping is %x, Entry point is %x, data_start is %x\n",
            (int)textpos, 0x00ffffff&ntohl(hdr->entry), ntohl(hdr->data_start));

    /* The main program needs a little extra setup in the task structure */
    start_code = textpos + sizeof (struct flat_hdr);
    end_code = textpos + text_len;
    if (id == 0) {
        current->mm->start_code = start_code;
        current->mm->end_code = end_code;
        current->mm->start_data = datapos;
        current->mm->end_data = datapos + data_len;
        /*
         * set up the brk stuff, uses any slack left in data/bss/stack
         * allocation.  We put the brk after the bss (between the bss
         * and stack) like other platforms.
         * Userspace code relies on the stack pointer starting out at
         * an address right at the end of a page.
         */
        current->mm->start_brk = datapos + data_len + bss_len;
        current->mm->brk = (current->mm->start_brk + 3) & ~3;
        current->mm->context.end_brk = memp + memp_size - stack_len;
    }

    if (flags & FLAT_FLAG_KTRACE)
        printk("%s %s: TEXT=%x-%x DATA=%x-%x BSS=%x-%x\n",
            id ? "Lib" : "Load", bprm->filename,
            (int) start_code, (int) end_code,
            (int) datapos,
            (int) (datapos + data_len),
            (int) (datapos + data_len),
            (int) (((datapos + data_len + bss_len) + 3) & ~3));

    text_len -= sizeof(struct flat_hdr); /* the real code len */

    /* Store the current module values into the global library structure */
    libinfo->lib_list[id].start_code = start_code;
    libinfo->lib_list[id].start_data = datapos;
    libinfo->lib_list[id].start_brk = datapos + data_len + bss_len;
    libinfo->lib_list[id].text_len = text_len;
    libinfo->lib_list[id].loaded = 1;
    libinfo->lib_list[id].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
    libinfo->lib_list[id].build_date = ntohl(hdr->build_date);
    
    /*
     * We just load the allocations into some temporary memory to
     * help simplify all this mumbo jumbo
     *
     * We've got two different sections of relocation entries.
     * The first is the GOT which resides at the beginning of the data segment
     * and is terminated with a -1.  This one can be relocated in place.
     * The second is the extra relocation entries tacked after the image's
     * data segment. These require a little more processing as the entry is
     * really an offset into the image which contains an offset into the
     * image.
     */
    if (flags & FLAT_FLAG_GOTPIC) {
        for (rp = (unsigned long *)datapos; *rp != 0xffffffff; rp++) {
            unsigned long addr;
            if (*rp) {
                addr = calc_reloc(*rp, libinfo, id, 0);
                if (addr == RELOC_FAILED) {
                    ret = -ENOEXEC;
                    goto err;
                }
                *rp = addr;
            }
        }
    }

    /*
     * Now run through the relocation entries.
     * We've got to be careful here as C++ produces relocatable zero
     * entries in the constructor and destructor tables which are then
     * tested for being not zero (which will always occur unless we're
     * based from address zero).  This causes an endless loop as __start
     * is at zero.  The solution used is to not relocate zero addresses.
     * This has the negative side effect of not allowing a global data
     * reference to be statically initialised to _stext (I've moved
     * __start to address 4 so that is okay).
     */
    if (rev > OLD_FLAT_VERSION) {
        unsigned long persistent = 0;
        for (i=0; i < relocs; i++) {
            unsigned long addr, relval;

            /* Get the address of the pointer to be
               relocated (of course, the address has to be
               relocated first).  */
            relval = ntohl(reloc[i]);
            if (flat_set_persistent (relval, &persistent))
                continue;
            addr = flat_get_relocate_addr(relval);
            rp = (unsigned long *) calc_reloc(addr, libinfo, id, 1);
            if (rp == (unsigned long *)RELOC_FAILED) {
                ret = -ENOEXEC;
                goto err;
            }

            /* Get the pointer's value.  */
            addr = flat_get_addr_from_rp(rp, relval, flags,
                            &persistent);
            if (addr != 0) {
                /*
                 * Do the relocation.  PIC relocs in the data section are
                 * already in target order
                 */
                if ((flags & FLAT_FLAG_GOTPIC) == 0)
                    addr = ntohl(addr);
                addr = calc_reloc(addr, libinfo, id, 0);
                if (addr == RELOC_FAILED) {
                    ret = -ENOEXEC;
                    goto err;
                }

                /* Write back the relocated pointer.  */
                flat_put_addr_at_rp(rp, addr, relval);
            }
        }
    } else {
        for (i=0; i < relocs; i++)
            old_reloc(ntohl(reloc[i]));
    }
    
    flush_icache_range(start_code, end_code);

    /* zero the BSS,  BRK and stack areas */
    memset((void*)(datapos + data_len), 0, bss_len + 
            (memp + memp_size - stack_len -     /* end brk */
            libinfo->lib_list[id].start_brk) +  /* start brk */
            stack_len);

    return 0;
err:
    return ret;
}


/****************************************************************************/
#ifdef CONFIG_BINFMT_SHARED_FLAT

/*
 * Load a shared library into memory.  The library gets its own data
 * segment (including bss) but not argv/argc/environ.
 */

static int load_flat_shared_library(int id, struct lib_info *libs)
{
    struct linux_binprm bprm;
    int res;
    char buf[16];

    memset(&bprm, 0, sizeof(bprm));

    /* Create the file name */
    sprintf(buf, "/lib/lib%d.so", id);

    /* Open the file up */
    bprm.filename = buf;
    bprm.file = open_exec(bprm.filename);
    res = PTR_ERR(bprm.file);
    if (IS_ERR(bprm.file))
        return res;

    bprm.cred = prepare_exec_creds();
    res = -ENOMEM;
    if (!bprm.cred)
        goto out;

    /* We don't really care about recalculating credentials at this point
     * as we're past the point of no return and are dealing with shared
     * libraries.
     */
    bprm.cred_prepared = 1;

    res = prepare_binprm(&bprm);

    if (!IS_ERR_VALUE(res))
        res = load_flat_file(&bprm, libs, id, NULL);

    abort_creds(bprm.cred);

out:
    allow_write_access(bprm.file);
    fput(bprm.file);

    return(res);
}

#endif /* CONFIG_BINFMT_SHARED_FLAT */
/****************************************************************************/

/*
 * These are the functions used to load flat style executables and shared
 * libraries.  There is no binary dependent code anywhere else.
 */

static int load_flat_binary(struct linux_binprm * bprm, struct pt_regs * regs)
{
    struct lib_info libinfo;
    unsigned long p = bprm->p;
    unsigned long stack_len;
    unsigned long start_addr;
    unsigned long *sp;
    int res;
    int i, j;

    memset(&libinfo, 0, sizeof(libinfo));
    /*
     * We have to add the size of our arguments to our stack size
     * otherwise it's too easy for users to create stack overflows
     * by passing in a huge argument list.  And yes,  we have to be
     * pedantic and include space for the argv/envp array as it may have
     * a lot of entries.
     */
#define TOP_OF_ARGS (PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *))
    stack_len = TOP_OF_ARGS - bprm->p;             /* the strings */
    stack_len += (bprm->argc + 1) * sizeof(char *); /* the argv array */
    stack_len += (bprm->envc + 1) * sizeof(char *); /* the envp array */
    stack_len += FLAT_STACK_ALIGN - 1;  /* reserve for upcoming alignment */
    
    res = load_flat_file(bprm, &libinfo, 0, &stack_len);
    if (IS_ERR_VALUE(res))
        return res;
    
    /* Update data segment pointers for all libraries */
    for (i=0; i<MAX_SHARED_LIBS; i++)
        if (libinfo.lib_list[i].loaded)
            for (j=0; j<MAX_SHARED_LIBS; j++)
                (-(j+1))[(unsigned long *)(libinfo.lib_list[i].start_data)] =
                    (libinfo.lib_list[j].loaded)?
                        libinfo.lib_list[j].start_data:UNLOADED_LIB;

    install_exec_creds(bprm);

    set_binfmt(&flat_format);

    p = ((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
    DBG_FLT("p=%x\n", (int)p);

    /* copy the arg pages onto the stack, this could be more efficient :-) */
    for (i = TOP_OF_ARGS - 1; i >= bprm->p; i--)
        * (char *) --p =
            ((char *) page_address(bprm->page[i/PAGE_SIZE]))[i % PAGE_SIZE];

    sp = (unsigned long *) create_flat_tables(p, bprm);
    
    /* Fake some return addresses to ensure the call chain will
     * initialise library in order for us.  We are required to call
     * lib 1 first, then 2, ... and finally the main program (id 0).
     */
    start_addr = libinfo.lib_list[0].entry;

#ifdef CONFIG_BINFMT_SHARED_FLAT
    for (i = MAX_SHARED_LIBS-1; i>0; i--) {
        if (libinfo.lib_list[i].loaded) {
            /* Push previos first to call address */
            --sp;   put_user(start_addr, sp);
            start_addr = libinfo.lib_list[i].entry;
        }
    }
#endif
    
    /* Stash our initial stack pointer into the mm structure */
    current->mm->start_stack = (unsigned long )sp;

#ifdef FLAT_PLAT_INIT
    FLAT_PLAT_INIT(regs);
#endif
    DBG_FLT("start_thread(regs=0x%x, entry=0x%x, start_stack=0x%x)\n",
        (int)regs, (int)start_addr, (int)current->mm->start_stack);
    
    start_thread(regs, start_addr, current->mm->start_stack);

    return 0;
}

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

static int __init init_flat_binfmt(void)
{
    register_binfmt(&flat_format);
    return 0;
}

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

core_initcall(init_flat_binfmt);

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