backends/arm_cfi.c

/* arm ABI-specified defaults for DWARF CFI.
   Copyright (C) 2013 Red Hat, Inc.
   This file is part of elfutils.

   This file is free software; you can redistribute it and/or modify
   it under the terms of either

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at
       your option) any later version

   or

     * 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

   or both in parallel, as here.

   elfutils 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 copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see <http://www.gnu.org/licenses/>.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <dwarf.h>

#define BACKEND arm_
#include "libebl_CPU.h"


/* ABI-specified state of DWARF CFI based on:

   "DWARF for the ARM Architecture ABI r2.09"
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0040b/IHI0040B_aadwarf.pdf

   "Procedure Call Standard for the ARM Architecture ABI r2.09"
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042e/IHI0042E_aapcs.pdf
*/

int
arm_abi_cfi (Ebl *ebl __attribute__ ((unused)), Dwarf_CIE *abi_info)
{
  static const uint8_t abi_cfi[] =
    {
      /* The initial Canonical Frame Address is the value of the
         Stack Pointer (r13) as setup in the previous frame. */
      DW_CFA_def_cfa, ULEB128_7 (13), ULEB128_7 (0),

      /* The Stack Pointer (r13) is restored from CFA address by default.  */
      DW_CFA_val_offset, ULEB128_7 (13), ULEB128_7 (0),

#define SV(n) DW_CFA_same_value, ULEB128_7 (n)
      /* Callee-saved regs r4-r8, r10, r11.  */
      SV (4), SV (5), SV (6), SV (7), SV (8), SV (10), SV (11),

      /* The link register contains the return address setup by caller.  */
      SV (14),
      DW_CFA_register, ULEB128_7 (15), ULEB128_7 (14), /* pc = lr */
#undef SV

      /* VFP S16-S31/D8-D15/Q4-Q7 are callee saved.
         And uleb128 encoded with two bytes.  */
#define ULEB128_8_2(x) ((x & 0x7f) | 0x80), 0x02
#define SV(n) DW_CFA_same_value, ULEB128_8_2 (n)
      SV (264), SV (265), SV (266), SV (267),
      SV (268), SV (269), SV (270), SV (271),

      /* XXX Note: registers intentionally unused by the program,
	 for example as a consequence of the procedure call standard
	 should be initialized as if by DW_CFA_same_value.  */
    };
#undef ULEB128_8_2
#undef SV

  abi_info->initial_instructions = abi_cfi;
  abi_info->initial_instructions_end = &abi_cfi[sizeof abi_cfi];
  abi_info->data_alignment_factor = 4;

  abi_info->return_address_register = 15; /* pc.  */

  return 0;
}