px4-firmware/nuttx/binfmt/libnxflat/libnxflat_bind.c

/****************************************************************************
 * binfmt/libnxflat/libnxflat_bind.c
 *
 *   Copyright (C) 2009 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <stdint.h>
#include <string.h>
#include <nxflat.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>

#include <arpa/inet.h>
#include <nuttx/binfmt/nxflat.h>
#include <nuttx/binfmt/symtab.h>

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/* CONFIG_DEBUG, CONFIG_DEBUG_VERBOSE, and CONFIG_DEBUG_BINFMT have to be
 * defined or CONFIG_NXFLAT_DUMPBUFFER does nothing.
 */

#if !defined(CONFIG_DEBUG_VERBOSE) || !defined (CONFIG_DEBUG_BINFMT)
#  undef CONFIG_NXFLAT_DUMPBUFFER
#endif

#ifdef CONFIG_NXFLAT_DUMPBUFFER
# define nxflat_dumpbuffer(m,b,n) bvdbgdumpbuffer(m,b,n)
#else
# define nxflat_dumpbuffer(m,b,n)
#endif

/****************************************************************************
 * Private Types
 ****************************************************************************/

/****************************************************************************
 * Private Data
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: nxflat_bindrel32i
 *
 * Description:
 *   Perform the NXFLAT_RELOC_TYPE_REL32I binding:
 *
 *   Meaning: Object file contains a 32-bit offset into I-Space at the offset.
 *   Fixup:   Add mapped I-Space address to the offset.
 *
 * Returned Value:
 *   0 (OK) is returned on success and a negated errno is returned on
 *   failure.
 *
 ****************************************************************************/

static inline int nxflat_bindrel32i(FAR struct nxflat_loadinfo_s *loadinfo,
                                    uint32_t offset)
{
  uint32_t *addr;

  bvdbg("NXFLAT_RELOC_TYPE_REL32I Offset: %08x I-Space: %p\n",
        offset, loadinfo->ispace + sizeof(struct nxflat_hdr_s));

  if (offset < loadinfo->dsize)
    {
      addr = (uint32_t*)(offset + loadinfo->dspace->region);
      bvdbg("  Before: %08x\n", *addr);
     *addr += (uint32_t)(loadinfo->ispace + sizeof(struct nxflat_hdr_s));
      bvdbg("  After: %08x\n", *addr);
      return OK;
    }
  else
    {
      bdbg("Offset: %08 does not lie in D-Space size: %08x\n",
           offset, loadinfo->dsize);
      return -EINVAL;
    }
}

/****************************************************************************
 * Name: nxflat_bindrel32d
 *
 * Description:
 *   Perform the NXFLAT_RELOC_TYPE_REL32D binding:
 *
 *   Meaning: Object file contains a 32-bit offset into D-Space at the offset.
 *   Fixup:   Add allocated D-Space address to the offset.
 *
 * Returned Value:
 *   0 (OK) is returned on success and a negated errno is returned on
 *   failure.
 *
 ****************************************************************************/

static inline int nxflat_bindrel32d(FAR struct nxflat_loadinfo_s *loadinfo,
                                    uint32_t offset)
{
  uint32_t *addr;

  bvdbg("NXFLAT_RELOC_TYPE_REL32D Offset: %08x D-Space: %p\n",
        offset, loadinfo->dspace->region);

  if (offset < loadinfo->dsize)
    {
      addr = (uint32_t*)(offset + loadinfo->dspace->region);
      bvdbg("  Before: %08x\n", *addr);
     *addr += (uint32_t)(loadinfo->dspace->region);
      bvdbg("  After: %08x\n", *addr);
      return OK;
    }
  else
    {
      bdbg("Offset: %08 does not lie in D-Space size: %08x\n",
           offset, loadinfo->dsize);
      return -EINVAL;
    }
}

/****************************************************************************
 * Name: nxflat_bindrel32id
 *
 * Description:
 *   Perform the NXFLAT_RELOC_TYPE_REL32ID binding:
 *
 *   Meaning: Object file contains a 32-bit offset into I-Space at the offset
 *            that will unfortunately be references relative to the GOT
 *   Fixup:   Add allocated the mapped I-Space address MINUS the allocated
 *            D-Space address to the offset.
 *
 * Returned Value:
 *   0 (OK) is returned on success and a negated errno is returned on
 *   failure.
 *
 ****************************************************************************/

#ifdef NXFLAT_RELOC_TYPE_REL32ID
static inline int nxflat_bindrel32id(FAR struct nxflat_loadinfo_s *loadinfo,
                                     uint32_t offset)
{
  uint32_t *addr;

  bvdbg("NXFLAT_RELOC_TYPE_REL32D Offset: %08x D-Space: %p\n",
        offset, loadinfo->dspace->region);

  if (offset < loadinfo->dsize)
    {
      addr = (uint32_t*)(offset + loadinfo->dspace->region);
      bvdbg("  Before: %08x\n", *addr);
     *addr += ((uint32_t)loadinfo->ispace - (uint32_t)(loadinfo->dspace->region));
      bvdbg("  After: %08x\n", *addr);
      return OK;
    }
  else
    {
      bdbg("Offset: %08 does not lie in D-Space size: %08x\n",
           offset, loadinfo->dsize);
      return -EINVAL;
    }
}
#endif

/****************************************************************************
 * Name: nxflat_gotrelocs
 *
 * Description:
 *   Bind all of the GOT relocations in the loaded module described by
 *   'loadinfo'
 *
 * Returned Value:
 *   0 (OK) is returned on success and a negated errno is returned on
 *   failure.
 *
 ****************************************************************************/

static inline int nxflat_gotrelocs(FAR struct nxflat_loadinfo_s *loadinfo)
{
  FAR struct nxflat_reloc_s *relocs;
  FAR struct nxflat_reloc_s  reloc;
  FAR struct nxflat_hdr_s   *hdr;
  uint32_t offset;
  uint16_t nrelocs;
  int      ret;
  int      result;
  int      i;

  /* The NXFLAT header is the first thing at the beginning of the ISpace. */

  hdr = (FAR struct nxflat_hdr_s*)loadinfo->ispace;

  /* From this, we can get the list of relocation entries. */

  /* From this, we can get the offset to the list of relocation entries */

  offset  = ntohl(hdr->h_relocstart);
  nrelocs = ntohs(hdr->h_reloccount);
  bvdbg("offset: %08lx nrelocs: %d\n", (long)offset, nrelocs);

  /* The value of the relocation list that we get from the header is a
   * file offset.  We will have to convert this to an offset into the
   * DSpace segment to get the pointer to the beginning of the relocation
   * list.
   */

  DEBUGASSERT(offset >= loadinfo->isize);
  DEBUGASSERT(offset + nrelocs * sizeof(struct nxflat_reloc_s)
              <= (loadinfo->isize + loadinfo->dsize));

  relocs = (FAR struct nxflat_reloc_s*)
        (offset - loadinfo->isize + loadinfo->dspace->region);
  bvdbg("isize: %08lx dpsace: %p relocs: %p\n", 
        (long)loadinfo->isize, loadinfo->dspace->region, relocs);

  /* Now, traverse the relocation list of and bind each GOT relocation. */

  ret = OK; /* Assume success */
  for (i = 0; i < nrelocs; i++)
    {
      /* Handle the relocation by the relocation type */

      reloc = *relocs++;
      result = OK;
      switch (NXFLAT_RELOC_TYPE(reloc.r_info))
        {
        /* NXFLAT_RELOC_TYPE_REL32I  Meaning: Object file contains a 32-bit offset
         *                                    into I-Space at the offset.
         *                           Fixup:   Add mapped I-Space address to the offset.
         */

        case NXFLAT_RELOC_TYPE_REL32I:
          {
            result = nxflat_bindrel32i(loadinfo, NXFLAT_RELOC_OFFSET(reloc.r_info));
          }
          break;

        /* NXFLAT_RELOC_TYPE_REL32D  Meaning: Object file contains a 32-bit offset
         *                                    into D-Space at the offset.
         *                           Fixup:   Add allocated D-Space address to the
         *                                    offset.
         */

        case NXFLAT_RELOC_TYPE_REL32D:
          {
            result = nxflat_bindrel32d(loadinfo, NXFLAT_RELOC_OFFSET(reloc.r_info));
          }
          break;

        /* NXFLAT_RELOC_TYPE_REL32ID Meaning: Object file contains a 32-bit offset
         *                                    into I-Space at the offset that will
         *                                    unfortunately be references relative
         *                                    to the GOT
         *                           Fixup:   Add allocated the mapped I-Space
         *                                    address MINUS the allocated D-Space
         *                                    address to the offset.
         */

#ifdef NXFLAT_RELOC_TYPE_REL32ID
        case NXFLAT_RELOC_TYPE_REL32ID:
          {
            result = nxflat_bindrel32id(loadinfo, NXFLAT_RELOC_OFFSET(reloc.r_info));
          }
          break;
#endif

        default:
          {
            bdbg("ERROR: Unrecognized relocation type: %d\n", NXFLAT_RELOC_TYPE(reloc.r_info));
            result = -EINVAL;
          }
          break;
        }

      /* Check for failures */

      if (result < 0 && ret == OK)
        {
          ret = result;
        }
    }

  /* Dump the relocation got */

#ifdef CONFIG_NXFLAT_DUMPBUFFER
  if (ret == OK && nrelocs > 0)
    {
      relocs = (FAR struct nxflat_reloc_s*)(offset - loadinfo->isize + loadinfo->dspace->region);
      nxflat_dumpbuffer("GOT", (FAR const uint8_t*)relocs, nrelocs * sizeof(struct nxflat_reloc_s));
    }
#endif

  return ret;
}

/****************************************************************************
 * Name: nxflat_bindimports
 *
 * Description:
 *   Bind the imported symbol names in the loaded module described by
 *   'loadinfo' using the exported symbol values provided by 'symtab'
 *
 * Returned Value:
 *   0 (OK) is returned on success and a negated errno is returned on
 *   failure.
 *
 ****************************************************************************/

static inline int nxflat_bindimports(FAR struct nxflat_loadinfo_s *loadinfo,
                                       FAR const struct symtab_s *exports,
                                       int nexports)
{
  FAR struct nxflat_import_s *imports;
  FAR struct nxflat_hdr_s    *hdr;
  FAR const struct symtab_s *symbol;

  char    *symname;
  uint32_t offset;
  uint16_t nimports;
  int      i;

  /* The NXFLAT header is the first thing at the beginning of the ISpace. */

  hdr = (FAR struct nxflat_hdr_s*)loadinfo->ispace;

  /* From this, we can get the offset to the list of symbols imported by
   * this module and the number of symbols imported by this module.
   */

  offset   = ntohl(hdr->h_importsymbols);
  nimports = ntohs(hdr->h_importcount);
  bvdbg("Imports offset: %08x nimports: %d\n", offset, nimports);

  /* Verify that this module requires imported symbols */

  if (offset != 0 && nimports > 0)
    {
      /* It does.. make sure that exported symbols are provided */

      DEBUGASSERT(exports && nexports > 0);

      /* If non-zero, the value of the imported symbol list that we get
       * from the header is a file offset.  We will have to convert this
       * to an offset into the DSpace segment to get the pointer to the
       * beginning of the imported symbol list.
       */

      DEBUGASSERT(offset >= loadinfo->isize &&
                  offset < loadinfo->isize + loadinfo->dsize);

      imports = (struct nxflat_import_s*)
        (offset - loadinfo->isize + loadinfo->dspace->region);

      /* Now, traverse the list of imported symbols and attempt to bind
       * each symbol to the value exported by from the exported symbol
       * table.
       */

      for (i = 0; i < nimports; i++)
        {
          bvdbg("Import[%d] (%08p) offset: %08x func: %08x\n",
                i, &imports[i], imports[i].i_funcname, imports[i].i_funcaddress);

          /* Get a pointer to the imported symbol name.  The name itself
           * lies in the TEXT segment.  But the reference to the name
           * lies in DATA segment.  Therefore, the name reference should
           * have been relocated when the module was loaded.
           */

          offset = imports[i].i_funcname;
          DEBUGASSERT(offset < loadinfo->isize);

          symname = (char*)(offset + loadinfo->ispace + sizeof(struct nxflat_hdr_s));

          /* Find the exported symbol value for this this symbol name. */

#ifdef CONFIG_SYMTAB_ORDEREDBYNAME
          symbol = symtab_findorderedbyname(exports, symname, nexports);
#else
          symbol = symtab_findbyname(exports, symname, nexports);
#endif
          if (!symbol)
            {
              bdbg("Exported symbol \"%s\" not found\n", symname);
              return -ENOENT;
            }

          /* And put this into the module's import structure. */

          imports[i].i_funcaddress =  (uint32_t)symbol->sym_value;

          bvdbg("Bound import[%d] (%08p) to export '%s' (%08x)\n",
                i, &imports[i], symname, imports[i].i_funcaddress);
        }
    }

  /* Dump the relocation import table */

#ifdef CONFIG_NXFLAT_DUMPBUFFER
  if (nimports > 0)
    {
      nxflat_dumpbuffer("Imports", (FAR const uint8_t*)imports, nimports * sizeof(struct nxflat_import_s));
    }
#endif

  return OK;
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: nxflat_bind
 *
 * Description:
 *   Bind the imported symbol names in the loaded module described by
 *   'loadinfo' using the exported symbol values provided by 'symtab'.
 *   After binding the module, clear the BSS region (which held the relocation
 *   data) in preparation for execution.
 *
 * Returned Value:
 *   0 (OK) is returned on success and a negated errno is returned on
 *   failure.
 *
 ****************************************************************************/

int nxflat_bind(FAR struct nxflat_loadinfo_s *loadinfo,
                FAR const struct symtab_s *exports, int nexports)
{
  /* Bind the imported symbol, absolute relocations separately.  This is done
   * before the standard relocations because that logic may modify the
   * import list (for the better hopefully, but we don't want to depend on it).
   */

  int ret = nxflat_bindimports(loadinfo, exports, nexports);
  if (ret == OK)
    {
      /* Then bind all GOT relocations */

      ret = nxflat_gotrelocs(loadinfo);
      if (ret == OK)
        {
          /* Zero the BSS area, trashing the relocations that lived in that
           * space in the loaded file.
           */

          memset((void*)(loadinfo->dspace->region + loadinfo->datasize),
                      0, loadinfo->bsssize);
        }
    }

  return ret;
}