/****************************************************************************/
/*
 *  linux/fs/binfmt_flat.c
 *
 *      Copyright (C) 2000-2003 David McCullough <davidm@snapgear.com>
 *      Copyright (C) 2002 Greg Ungerer <gerg@snapgear.com>
 *      Copyright (C) 2002 SnapGear, by Paul Dale <pauli@snapgear.com>
 *      Copyright (C) 2000, 2001 Lineo, by David McCullough <davidm@lineo.com>
 *  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 <kjahds@kjahds.com>
 *      JAN/99 -- coded full program relocation (gerg@snapgear.com)
 */

#include <linux/module.h>
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/a.out.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 <asm/byteorder.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/unaligned.h>
#include <asm/cacheflush.h>

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

#if 0
#define DEBUG 1
#endif

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

#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(long signr, struct pt_regs * regs, struct file *file);

extern void dump_thread(struct pt_regs *, struct user *);

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(long signr, struct pt_regs * regs, struct file *file)
{
        printk("Process %s:%d received signr %d and should have core dumped\n",
                        current->comm, current->pid, (int) signr);
        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 dummy;

        sp = (unsigned long *) ((-(unsigned long)sizeof(char *))&(unsigned long) p);

        sp -= envc+1;
        envp = sp;
        sp -= argc+1;
        argv = sp;

        flat_stack_align(sp);
        if (flat_argvp_envp_on_stack()) {
                --sp; put_user((unsigned long) envp, sp);
                --sp; put_user((unsigned long) argv, sp);
        }

        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;

        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");
                return -ENOMEM;
        }

        /* 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;

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

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

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

        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");
                        return -ENOEXEC;
                }
        }
        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");
                        return -ENOEXEC;
                }
        }
        if (buf[3] & COMMENT) {
                for (;  ret < LBUFSIZE && (buf[ret] != 0); ret++)
                        ;
                if (unlikely(LBUFSIZE == ret)) {
                        DBG_FLT("binfmt_flat: buffer overflow (COMMENT)?\n");
                        return -ENOEXEC;
                }
        }

        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");
                return -ENOEXEC;
        }

        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);
                return -ENOEXEC;
        }

        zlib_inflateEnd(&strm);
        kfree(buf);
        kfree(strm.workspace);
        return 0;
}

#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 &&
                                load_flat_shared_library(id, p) > (unsigned long) -4096) {
                        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_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:
        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 memp = 0; /* for finding the brk area */
        unsigned long extra, rlim;
        unsigned long *reloc = 0, *rp;
        struct inode *inode;
        int i, rev, relocs = 0;
        loff_t fpos;
        unsigned long start_code, end_code;

        hdr = ((struct flat_hdr *) bprm->buf);          /* exec-header */
        inode = bprm->file->f_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 (flags & FLAT_FLAG_KTRACE)
                printk("BINFMT_FLAT: Loading file: %s\n", bprm->filename);

        if (strncmp(hdr->magic, "bFLT", 4) ||
                        (rev != FLAT_VERSION && rev != OLD_FLAT_VERSION)) {
                /*
                 * because a lot of people do not manage to produce good
                 * flat binaries,  we leave this printk to help them realise
                 * the problem.  We only print the error if its not a script file
                 */
                if (strncmp(hdr->magic, "#!", 2))
                        printk("BINFMT_FLAT: bad magic/rev (0x%x, need 0x%x)\n",
                                        rev, (int) FLAT_VERSION);
                return -ENOEXEC;
        }
        
        /* 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);
                return -ENOEXEC;
        }

        /*
         * 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");
                return -ENOEXEC;
        }
#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 = current->rlim[RLIMIT_DATA].rlim_cur;
        if (rlim >= RLIM_INFINITY)
                rlim = ~0;
        if (data_len + bss_len > rlim)
                return -ENOMEM;

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

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

        /*
         * calculate the extra space we need to map in
         */
        extra = max(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");

                down_write(&current->mm->mmap_sem);
                textpos = do_mmap(bprm->file, 0, text_len, PROT_READ|PROT_EXEC, 0, 0);
                up_write(&current->mm->mmap_sem);
                if (!textpos  || textpos >= (unsigned long) -4096) {
                        if (!textpos)
                                textpos = (unsigned long) -ENOMEM;
                        printk("Unable to mmap process text, errno %d\n", (int)-textpos);
                        return(textpos);
                }

                down_write(&current->mm->mmap_sem);
                realdatastart = do_mmap(0, 0, data_len + extra +
                                MAX_SHARED_LIBS * sizeof(unsigned long),
                                PROT_READ|PROT_WRITE|PROT_EXEC, 0, 0);
                up_write(&current->mm->mmap_sem);

                if (realdatastart == 0 || realdatastart >= (unsigned long)-4096) {
                        if (!realdatastart)
                                realdatastart = (unsigned long) -ENOMEM;
                        printk("Unable to allocate RAM for process data, errno %d\n",
                                        (int)-datapos);
                        do_munmap(current->mm, textpos, text_len);
                        return realdatastart;
                }
                datapos = realdatastart + MAX_SHARED_LIBS * sizeof(unsigned long);

                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 (result >= (unsigned long)-4096) {
                        printk("Unable to read data+bss, errno %d\n", (int)-result);
                        do_munmap(current->mm, textpos, text_len);
                        do_munmap(current->mm, realdatastart, data_len + extra);
                        return result;
                }

                reloc = (unsigned long *) (datapos+(ntohl(hdr->reloc_start)-text_len));
                memp = realdatastart;

        } else {

                down_write(&current->mm->mmap_sem);
                textpos = do_mmap(0, 0, text_len + data_len + extra +
                                        MAX_SHARED_LIBS * sizeof(unsigned long),
                                PROT_READ | PROT_EXEC | PROT_WRITE, 0, 0);
                up_write(&current->mm->mmap_sem);
                if (!textpos  || textpos >= (unsigned long) -4096) {
                        if (!textpos)
                                textpos = (unsigned long) -ENOMEM;
                        printk("Unable to allocate RAM for process text/data, errno %d\n",
                                        (int)-textpos);
                        return(textpos);
                }

                realdatastart = textpos + ntohl(hdr->data_start);
                datapos = realdatastart + MAX_SHARED_LIBS * sizeof(unsigned long);
                reloc = (unsigned long *) (textpos + ntohl(hdr->reloc_start) +
                                MAX_SHARED_LIBS * sizeof(unsigned long));
                memp = textpos;

#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 (result < (unsigned long) -4096)
                                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 (result < (unsigned long) -4096) {
                                fpos = ntohl(hdr->data_start);
                                result = bprm->file->f_op->read(bprm->file, (char *) datapos,
                                        data_len + (relocs * sizeof(unsigned long)), &fpos);
                        }
                }
                if (result >= (unsigned long)-4096) {
                        printk("Unable to read code+data+bss, errno %d\n",(int)-result);
                        do_munmap(current->mm, textpos, text_len + data_len + extra +
                                MAX_SHARED_LIBS * sizeof(unsigned long));
                        return result;
                }
        }

        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.
                 */
                current->mm->start_brk = datapos + data_len + bss_len;
                current->mm->brk = (current->mm->start_brk + 3) & ~3;
                current->mm->context.end_brk = memp + ksize((void *) memp) - stack_len;
                current->mm->rss = 0;
        }

        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 begining 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)
                                        return -ENOEXEC;
                                *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) {
                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]);
                        addr = flat_get_relocate_addr(relval);
                        rp = (unsigned long *) calc_reloc(addr, libinfo, id, 1);
                        if (rp == (unsigned long *)RELOC_FAILED)
                                return -ENOEXEC;

                        /* Get the pointer's value.  */
                        addr = flat_get_addr_from_rp(rp, relval);
                        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)
                                        return -ENOEXEC;

                                /* 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 + ksize((void *) memp) - stack_len -      /* end brk */
                        libinfo->lib_list[id].start_brk) +              /* start brk */
                        stack_len);

        return 0;
}


/****************************************************************************/
#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];

        /* 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;

        res = prepare_binprm(&bprm);

        if (res <= (unsigned long)-4096)
                res = load_flat_file(&bprm, libs, id, NULL);
        if (bprm.file) {
                allow_write_access(bprm.file);
                fput(bprm.file);
                bprm.file = NULL;
        }
        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 */

        
        res = load_flat_file(bprm, &libinfo, 0, &stack_len);
        if (res > (unsigned long)-4096)
                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;

        compute_creds(bprm);
        current->flags &= ~PF_FORKNOEXEC;

        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;

        
        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);

        if (current->ptrace & PT_PTRACED)
                send_sig(SIGTRAP, current, 0);

        return 0;
}

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

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

static void __exit exit_flat_binfmt(void)
{
        unregister_binfmt(&flat_format);
}

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

module_init(init_flat_binfmt);
module_exit(exit_flat_binfmt);

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