path: root/nuttx/arch/arm/src/armv7-a/arm_elf.c

/****************************************************************************
 * arch/arm/src/armv-7a/arm_elf.c
 *
 *   Copyright (C) 2013-2014 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 <stdlib.h>
#include <elf32.h>
#include <errno.h>
#include <debug.h>

#include <arch/elf.h>
#include <nuttx/arch.h>
#include <nuttx/binfmt/elf.h>

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

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

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

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

/****************************************************************************
 * Name: up_checkarch
 *
 * Description:
 *   Given the ELF header in 'hdr', verify that the ELF file is appropriate
 *   for the current, configured architecture.  Every architecture that uses
 *   the ELF loader must provide this function.
 *
 * Input Parameters:
 *   hdr - The ELF header read from the ELF file.
 *
 * Returned Value:
 *   True if the architecture supports this ELF file.
 *
 ****************************************************************************/

bool up_checkarch(FAR const Elf32_Ehdr *ehdr)
{
  /* Make sure it's an ARM executable */

  if (ehdr->e_machine != EM_ARM)
    {
      bdbg("Not for ARM: e_machine=%04x\n", ehdr->e_machine);
      return -ENOEXEC;
    }

  /* Make sure that 32-bit objects are supported */

  if (ehdr->e_ident[EI_CLASS] != ELFCLASS32)
    {
      bdbg("Need 32-bit objects: e_ident[EI_CLASS]=%02x\n", ehdr->e_ident[EI_CLASS]);
      return -ENOEXEC;
    }

  /* Verify endian-ness */

#ifdef CONFIG_ENDIAN_BIG
  if (ehdr->e_ident[EI_DATA] != ELFDATA2MSB)
#else
  if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB)
#endif
    {
      bdbg("Wrong endian-ness: e_ident[EI_DATA]=%02x\n", ehdr->e_ident[EI_DATA]);
      return -ENOEXEC;
    }

  /* Make sure the entry point address is properly aligned */

  if ((ehdr->e_entry & 3) != 0)
    {
      bdbg("Entry point is not properly aligned: %08x\n", ehdr->e_entry);
      return -ENOEXEC;
    }

  /* TODO:  Check ABI here. */
  return OK;
}

/****************************************************************************
 * Name: up_relocate and up_relocateadd
 *
 * Description:
 *   Perform on architecture-specific ELF relocation.  Every architecture
 *   that uses the ELF loader must provide this function.
 *
 * Input Parameters:
 *   rel - The relocation type
 *   sym - The ELF symbol structure containing the fully resolved value.
 *         There are a few relocation types for a few architectures that do
 *         not require symbol information.  For those, this value will be
 *         NULL.  Implementations of these functions must be able to handle
 *         that case.
 *   addr - The address that requires the relocation.
 *
 * Returned Value:
 *   Zero (OK) if the relocation was successful.  Otherwise, a negated errno
 *   value indicating the cause of the relocation failure.
 *
 ****************************************************************************/

int up_relocate(FAR const Elf32_Rel *rel, FAR const Elf32_Sym *sym,
                uintptr_t addr)
{
  int32_t offset;
  unsigned int relotype;

  /* All relocations except R_ARM_V4BX depend upon having valid symbol
   * information.
   */

  relotype = ELF32_R_TYPE(rel->r_info);
  if (sym == NULL && relotype != R_ARM_NONE && relotype != R_ARM_V4BX)
    {
      return -EINVAL;
    }

  /* Handle the relocation by relocation type */

  switch (relotype)
    {
    case R_ARM_NONE:
      {
        /* No relocation */
      }
      break;

    case R_ARM_PC24:
    case R_ARM_CALL:
    case R_ARM_JUMP24:
      {
        bvdbg("Performing PC24 [%d] link at addr %08lx [%08lx] to sym '%s' st_value=%08lx\n",
              ELF32_R_TYPE(rel->r_info), (long)addr, (long)(*(uint32_t*)addr),
              sym, (long)sym->st_value);

        offset = (*(uint32_t*)addr & 0x00ffffff) << 2;
        if (offset & 0x02000000)
          {
            offset -= 0x04000000;
          }

        offset += sym->st_value - addr;
        if (offset & 3 || offset <= (int32_t) 0xfe000000 || offset >= (int32_t) 0x02000000)
          {
            bdbg("  ERROR: PC24 [%d] relocation out of range, offset=%08lx\n",
                 ELF32_R_TYPE(rel->r_info), offset);

            return -EINVAL;
          }

        offset >>= 2;

        *(uint32_t*)addr &= 0xff000000;
        *(uint32_t*)addr |= offset & 0x00ffffff;
      }
      break;

    case R_ARM_ABS32:
    case R_ARM_TARGET1:  /* New ABI:  TARGET1 always treated as ABS32 */
      {
        bvdbg("Performing ABS32 link at addr=%08lx [%08lx] to sym=%p st_value=%08lx\n",
              (long)addr, (long)(*(uint32_t*)addr), sym, (long)sym->st_value);

        *(uint32_t*)addr += sym->st_value;
      }
      break;

    case R_ARM_V4BX:
      {
        bvdbg("Performing V4BX link at addr=%08lx [%08lx]\n",
              (long)addr, (long)(*(uint32_t*)addr));

         /* Preserve only Rm and the condition code */

        *(uint32_t*)addr &= 0xf000000f;

        /* Change instruction to 'mov pc, Rm' */

        *(uint32_t*)addr |= 0x01a0f000;
      }
      break;

    case R_ARM_PREL31:
      {
        bvdbg("Performing PREL31 link at addr=%08lx [%08lx] to sym=%p st_value=%08lx\n",
              (long)addr, (long)(*(uint32_t*)addr), sym, (long)sym->st_value);

        offset           = *(uint32_t*)addr + sym->st_value - addr;
        *(uint32_t*)addr = offset & 0x7fffffff;
      }
      break;

    case R_ARM_MOVW_ABS_NC:
    case R_ARM_MOVT_ABS:
      {
        bvdbg("Performing MOVx_ABS [%d] link at addr=%08lx [%08lx] to sym=%p st_value=%08lx\n",
              ELF32_R_TYPE(rel->r_info), (long)addr, (long)(*(uint32_t*)addr),
              sym, (long)sym->st_value);

        offset = *(uint32_t*)addr;
        offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
        offset = (offset ^ 0x8000) - 0x8000;

        offset += sym->st_value;
        if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
          {
            offset >>= 16;
          }

        *(uint32_t*)addr &= 0xfff0f000;
        *(uint32_t*)addr |= ((offset & 0xf000) << 4) | (offset & 0x0fff);
      }
      break;

    default:
      bdbg("Unsupported relocation: %d\n", ELF32_R_TYPE(rel->r_info));
      return -EINVAL;
    }

  return OK;
}

int up_relocateadd(FAR const Elf32_Rela *rel, FAR const Elf32_Sym *sym,
                   uintptr_t addr)
{
  bdbg("RELA relocation not supported\n");
  return -ENOSYS;
}