/* Adapteva epiphany specific support for 32-bit ELF
   Copyright (C) 2000-2021 Free Software Foundation, Inc.
   Contributed by Embecosm on behalf of Adapteva, Inc.

   This file is part of BFD, the Binary File Descriptor library.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program 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 a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
   MA 02110-1301, USA.  */

#include "sysdep.h"
#include "bfd.h"
#include "libbfd.h"
#include "elf-bfd.h"
#include "elf/epiphany.h"
#include "libiberty.h"

/* Struct used to pass miscellaneous paramaters which
   helps to avoid overly long parameter lists.  */
struct misc
{
  Elf_Internal_Shdr *  symtab_hdr;
  Elf_Internal_Rela *  irelbase;
  bfd_byte *	       contents;
  Elf_Internal_Sym *   isymbuf;
};

struct epiphany_opcode
{
  unsigned short opcode;
  unsigned short mask;
};

static bool epiphany_relaxed = false;

/* Relocation tables.  */
static reloc_howto_type epiphany_elf_howto_table [] =
{
#define AHOW(t,rs,s,bs,pr,bp,co,name,sm,dm)	\
    HOWTO(t,			/* type */ \
	  rs,			/* rightshift */ \
	  s,			/* size (0 = byte, 1 = short, 2 = long) */ \
	  bs,			/* bitsize */ \
	  pr,			/* pc_relative */ \
	  bp,			/* bitpos */ \
	  co,			/* complain_on_overflow */	       \
	  bfd_elf_generic_reloc,/* special_function */ \
	  name,			/* name */ \
	  false,		/* partial_inplace */ \
	  sm,			/* src_mask */ \
	  dm,			/* dst_mask */ \
	  pr)			/* pcrel_offset */

  /* This reloc does nothing.  */
  AHOW (R_EPIPHANY_NONE,    0, 3,0, false, 0, complain_overflow_dont,	  "R_EPIPHANY_NONE",	    0,		0),

  /* 8 bit absolute (not likely) */
  AHOW (R_EPIPHANY_8,	    0, 0, 8, false, 0, complain_overflow_bitfield, "R_EPIPHANY_8",	0x000000ff, 0x000000ff),
  /* 16 bit absolute */
  AHOW (R_EPIPHANY_16,	    0, 1,16, false, 0, complain_overflow_bitfield, "R_EPIPHANY_16",	0x0000ffff, 0x00ff1fe0),
  /* A 32 bit absolute relocation.  */
  AHOW (R_EPIPHANY_32,	    0, 2,32, false, 0, complain_overflow_dont,	   "R_EPIPHANY_32",	0xffffffff, 0xffffffff),

  /*  8 bit relative relocation */
  HOWTO ( R_EPIPHANY_8_PCREL,  0, 0,  8, true, 0, complain_overflow_bitfield, bfd_elf_generic_reloc, "R_EPIPHANY_8_PCREL", false, 0x000000ff, 0x000000ff, false),
  /* 16 bit relative relocation */
  HOWTO ( R_EPIPHANY_16_PCREL, 0, 1, 16, true, 0, complain_overflow_bitfield, bfd_elf_generic_reloc, "R_EPIPHANY_8_PCREL", false, 0x000000ff, 0x000000ff, false),
  /* 32 bit relative relocation */
  HOWTO ( R_EPIPHANY_32_PCREL, 0, 2, 32, true, 0, complain_overflow_bitfield, bfd_elf_generic_reloc, "R_EPIPHANY_8_PCREL", false, 0x000000ff, 0x000000ff, false),

  /* 8 bit pc-relative relocation */
  AHOW (R_EPIPHANY_SIMM8,   1, 0, 8,  true, 8, complain_overflow_signed,   "R_EPIPHANY_SIMM8",	 0x000000ff, 0x0000ff00),
  /* 24 bit pc-relative relocation */
  AHOW (R_EPIPHANY_SIMM24,  1, 2,24,  true, 8, complain_overflow_signed,   "R_EPIPHANY_SIMM24",	 0x00ffffff, 0xffffff00),

  /* %HIGH(EA) */
  AHOW (R_EPIPHANY_HIGH,    0, 2,16, false, 0, complain_overflow_dont,	   "R_EPIPHANY_HIGH",	 0x0ff01fe0, 0x0ff01fe0),

  /* %LOW(EA) */
  AHOW (R_EPIPHANY_LOW,	    0, 2,16, false, 0, complain_overflow_dont,	"R_EPIPHANY_LOW",     0x0ff01fe0, 0x0ff01fe0),

  /* simm11 */
  AHOW (R_EPIPHANY_SIMM11,  0, 2,11, false, 0, complain_overflow_bitfield, "R_EPIPHANY_SIMM11",	 0x00ff0380, 0x00ff0380),
  /* imm12 - sign-magnitude */
  AHOW (R_EPIPHANY_IMM11,   0, 2,11, false, 0, complain_overflow_bitfield, "R_EPIPHANY_IMM12",	 0x00ff0380, 0x00ff0380),
  /* imm8 */
  AHOW (R_EPIPHANY_IMM8,    0, 1, 8, false, 8, complain_overflow_signed,   "R_EPIPHANY_IMM8",	 0x0000ff00, 0x0000ff00)


};
#undef AHOW

/* Map BFD reloc types to EPIPHANY ELF reloc types.  */

static reloc_howto_type *
epiphany_reloc_type_lookup (bfd * abfd ATTRIBUTE_UNUSED,
			    bfd_reloc_code_real_type code)
{
  /* Note that the epiphany_elf_howto_table is indxed by the R_
     constants.  Thus, the order that the howto records appear in the
     table *must* match the order of the relocation types defined in
     include/elf/epiphany.h.  */

  switch (code)
    {
    case BFD_RELOC_NONE:
      return &epiphany_elf_howto_table[ (int) R_EPIPHANY_NONE];

    case BFD_RELOC_EPIPHANY_SIMM8:
      return &epiphany_elf_howto_table[ (int) R_EPIPHANY_SIMM8];
    case BFD_RELOC_EPIPHANY_SIMM24:
      return &epiphany_elf_howto_table[ (int) R_EPIPHANY_SIMM24];

    case BFD_RELOC_8_PCREL:
      return &epiphany_elf_howto_table[ (int) R_EPIPHANY_8_PCREL];
    case BFD_RELOC_16_PCREL:
      return &epiphany_elf_howto_table[ (int) R_EPIPHANY_16_PCREL];
    case BFD_RELOC_32_PCREL:
      return &epiphany_elf_howto_table[ (int) R_EPIPHANY_32_PCREL];

    case BFD_RELOC_8:
      return &epiphany_elf_howto_table[ (int) R_EPIPHANY_8];
    case BFD_RELOC_16:
      return &epiphany_elf_howto_table[ (int) R_EPIPHANY_16];
    case BFD_RELOC_32:
      return &epiphany_elf_howto_table[ (int) R_EPIPHANY_32];

    case BFD_RELOC_EPIPHANY_HIGH:
      return & epiphany_elf_howto_table[ (int) R_EPIPHANY_HIGH];
    case BFD_RELOC_EPIPHANY_LOW:
      return & epiphany_elf_howto_table[ (int) R_EPIPHANY_LOW];

    case BFD_RELOC_EPIPHANY_SIMM11:
      return & epiphany_elf_howto_table[ (int) R_EPIPHANY_SIMM11];
    case BFD_RELOC_EPIPHANY_IMM11:
      return & epiphany_elf_howto_table[ (int) R_EPIPHANY_IMM11];

    case BFD_RELOC_EPIPHANY_IMM8:
      return & epiphany_elf_howto_table[ (int) R_EPIPHANY_IMM8];

    default:
      /* Pacify gcc -Wall.  */
      return NULL;
    }
  return NULL;
}

static reloc_howto_type *
epiphany_reloc_name_lookup (bfd *abfd ATTRIBUTE_UNUSED, const char *r_name)
{
  unsigned int i;

  for (i = 0; i < ARRAY_SIZE (epiphany_elf_howto_table); i++)
    if (epiphany_elf_howto_table[i].name != NULL
	&& strcasecmp (epiphany_elf_howto_table[i].name, r_name) == 0)
      return &epiphany_elf_howto_table[i];

  return NULL;
}

#define PAGENO(ABSADDR) ((ABSADDR) & 0xFFFFC000)
#define BASEADDR(SEC)	((SEC)->output_section->vma + (SEC)->output_offset)

/* This function handles relaxing for the epiphany.
   Dummy placeholder for future optimizations.  */

static bool
epiphany_elf_relax_section (bfd *abfd, asection *sec,
			    struct bfd_link_info *link_info,
			    bool *again)
{
  Elf_Internal_Shdr *symtab_hdr;
  Elf_Internal_Rela *internal_relocs;
  bfd_byte *contents = NULL;
  Elf_Internal_Sym *isymbuf = NULL;
  static asection * first_section = NULL;
  static unsigned long search_addr;
  static unsigned long page_start = 0;
  static unsigned long page_end = 0;
  static unsigned int pass = 0;
  static bool new_pass = false;
  static bool changed = false;
  struct misc misc ATTRIBUTE_UNUSED;
  asection *stab;

  /* Assume nothing changes.  */
  *again = false;

  if (first_section == NULL)
    {
      epiphany_relaxed = true;
      first_section = sec;
    }

  if (first_section == sec)
    {
      pass++;
      new_pass = true;
    }

  /* We don't have to do anything for a relocatable link,
     if this section does not have relocs, or if this is
     not a code section.  */
  if (bfd_link_relocatable (link_info)
      || (sec->flags & SEC_RELOC) == 0
      || sec->reloc_count == 0
      || (sec->flags & SEC_CODE) == 0)
    return true;

  symtab_hdr = &elf_tdata (abfd)->symtab_hdr;

  internal_relocs = _bfd_elf_link_read_relocs (abfd, sec, NULL, NULL,
					       link_info->keep_memory);
  if (internal_relocs == NULL)
    goto error_return;

  /* Make sure the stac.rela stuff gets read in.  */
  stab = bfd_get_section_by_name (abfd, ".stab");

  if (stab)
    {
      /* So stab does exits.  */
      Elf_Internal_Rela * irelbase ATTRIBUTE_UNUSED;

      irelbase = _bfd_elf_link_read_relocs (abfd, stab, NULL, NULL,
					    link_info->keep_memory);
    }

  /* Get section contents cached copy if it exists.  */
  if (contents == NULL)
    {
      /* Get cached copy if it exists.  */
      if (elf_section_data (sec)->this_hdr.contents != NULL)
	contents = elf_section_data (sec)->this_hdr.contents;
      else
	{
	  /* Go get them off disk.  */
	  if (!bfd_malloc_and_get_section (abfd, sec, &contents))
	    goto error_return;
	}
    }

  /* Read this BFD's symbols cached copy if it exists.  */
  if (isymbuf == NULL && symtab_hdr->sh_info != 0)
    {
      isymbuf = (Elf_Internal_Sym *) symtab_hdr->contents;
      if (isymbuf == NULL)
	isymbuf = bfd_elf_get_elf_syms (abfd, symtab_hdr,
					symtab_hdr->sh_info, 0,
					NULL, NULL, NULL);
      if (isymbuf == NULL)
	goto error_return;
    }

  misc.symtab_hdr = symtab_hdr;
  misc.isymbuf = isymbuf;
  misc.irelbase = internal_relocs;
  misc.contents = contents;

  /* This is where all the relaxation actually get done.  */
  if ((pass == 1) || (new_pass && !changed))
    {
      /* On the first pass we simply search for the lowest page that
	 we havn't relaxed yet. Note that the pass count is reset
	 each time a page is complete in order to move on to the next page.
	 If we can't find any more pages then we are finished.  */
      if (new_pass)
	{
	  pass = 1;
	  new_pass = false;
	  changed = true; /* Pre-initialize to break out of pass 1.  */
	  search_addr = 0xFFFFFFFF;
	}

      if ((BASEADDR (sec) + sec->size < search_addr)
	  && (BASEADDR (sec) + sec->size > page_end))
	{
	  if (BASEADDR (sec) <= page_end)
	    search_addr = page_end + 1;
	  else
	    search_addr = BASEADDR (sec);

	  /* Found a page => more work to do.  */
	  *again = true;
	}
    }
  else
    {
      if (new_pass)
	{
	  new_pass = false;
	  changed = false;
	  page_start = PAGENO (search_addr);
	  page_end = page_start | 0x00003FFF;
	}

      /* Only process sections in range.  */
      if ((BASEADDR (sec) + sec->size >= page_start)
	  && (BASEADDR (sec) <= page_end))
	{
#if 0
	  if (!epiphany_elf_relax_section_page (abfd, sec, &changed, &misc,
						page_start, page_end))
#endif
	    return false;
	}
      *again = true;
    }

  /* Perform some house keeping after relaxing the section.  */

  if (isymbuf != NULL
      && symtab_hdr->contents != (unsigned char *) isymbuf)
    {
      if (! link_info->keep_memory)
	free (isymbuf);
      else
	symtab_hdr->contents = (unsigned char *) isymbuf;
    }

  if (contents != NULL
      && elf_section_data (sec)->this_hdr.contents != contents)
    {
      if (! link_info->keep_memory)
	free (contents);
      else
	{
	  /* Cache the section contents for elf_link_input_bfd.  */
	  elf_section_data (sec)->this_hdr.contents = contents;
	}
    }

  if (elf_section_data (sec)->relocs != internal_relocs)
    free (internal_relocs);

  return true;

 error_return:
  if (symtab_hdr->contents != (unsigned char *) isymbuf)
    free (isymbuf);
  if (elf_section_data (sec)->this_hdr.contents != contents)
    free (contents);
  if (elf_section_data (sec)->relocs != internal_relocs)
    free (internal_relocs);
  return false;
}

/* Set the howto pointer for a EPIPHANY ELF reloc.  */

static bool
epiphany_info_to_howto_rela (bfd * abfd,
			     arelent * cache_ptr,
			     Elf_Internal_Rela * dst)
{
  unsigned int r_type;

  r_type = ELF32_R_TYPE (dst->r_info);
  if (r_type >= (unsigned int) R_EPIPHANY_max)
    {
      /* xgettext:c-format */
      _bfd_error_handler (_("%pB: unsupported relocation type %#x"),
			  abfd, r_type);
      bfd_set_error (bfd_error_bad_value);
      return false;
    }
  cache_ptr->howto = & epiphany_elf_howto_table [r_type];
  return true;
}

/* Perform a single relocation.
   By default we use the standard BFD routines.  */

static bfd_reloc_status_type
epiphany_final_link_relocate (reloc_howto_type *  howto,
			      bfd *		  input_bfd,
			      asection *	  input_section,
			      bfd_byte *	  contents,
			      Elf_Internal_Rela * rel,
			      bfd_vma		  relocation)
{
  switch (howto->type)
    {
      /* Handle 16 bit immediates.  */
    case R_EPIPHANY_HIGH:
      relocation += rel->r_addend;
      relocation >>= 16;
      goto common;

    case R_EPIPHANY_LOW:
      relocation += rel->r_addend;
    common:
      relocation = ((relocation & 0xff00L) << 12)
	| ((relocation & 0x00ffL) << 5);
      /* Sanity check the address.  */
      if (rel->r_offset > bfd_get_section_limit (input_bfd, input_section))
	return bfd_reloc_outofrange;

      return _bfd_relocate_contents (howto, input_bfd, relocation,
				     contents + rel->r_offset);

    case R_EPIPHANY_SIMM11:
      relocation += rel->r_addend;
      /* Check signed overflow.  */
      if ((int)relocation > 1023 || (int)relocation < -1024)
	return bfd_reloc_outofrange;
      goto disp11;

    case R_EPIPHANY_IMM11:
      relocation += rel->r_addend;
      if ((unsigned int) relocation > 0x7ff)
	return bfd_reloc_outofrange;
      /* Fall through.  */
    disp11:
      relocation = (((relocation & 7) << 5)
		    | ((relocation & 0x7f8 ) << 13));
      return _bfd_relocate_contents (howto, input_bfd, relocation,
				     contents + rel->r_offset);

      /* Pass others through.  */
    default:
      break;
    }

  /* Only install relocation if above tests did not disqualify it.  */
  return _bfd_final_link_relocate (howto, input_bfd, input_section,
				   contents, rel->r_offset,
				   relocation, rel->r_addend);
}

/* Relocate an EPIPHANY ELF section.

   The RELOCATE_SECTION function is called by the new ELF backend linker
   to handle the relocations for a section.

   The relocs are always passed as Rela structures; if the section
   actually uses Rel structures, the r_addend field will always be
   zero.

   This function is responsible for adjusting the section contents as
   necessary, and (if using Rela relocs and generating a relocatable
   output file) adjusting the reloc addend as necessary.

   This function does not have to worry about setting the reloc
   address or the reloc symbol index.

   LOCAL_SYMS is a pointer to the swapped in local symbols.

   LOCAL_SECTIONS is an array giving the section in the input file
   corresponding to the st_shndx field of each local symbol.

   The global hash table entry for the global symbols can be found
   via elf_sym_hashes (input_bfd).

   When generating relocatable output, this function must handle
   STB_LOCAL/STT_SECTION symbols specially.  The output symbol is
   going to be the section symbol corresponding to the output
   section, which means that the addend must be adjusted
   accordingly.  */

static int
epiphany_elf_relocate_section (bfd *output_bfd ATTRIBUTE_UNUSED,
			       struct bfd_link_info *info,
			       bfd *input_bfd,
			       asection *input_section,
			       bfd_byte *contents,
			       Elf_Internal_Rela *relocs,
			       Elf_Internal_Sym *local_syms,
			       asection **local_sections)
{
  Elf_Internal_Shdr *symtab_hdr;
  struct elf_link_hash_entry **sym_hashes;
  Elf_Internal_Rela *rel;
  Elf_Internal_Rela *relend;

  symtab_hdr = & elf_tdata (input_bfd)->symtab_hdr;
  sym_hashes = elf_sym_hashes (input_bfd);
  relend     = relocs + input_section->reloc_count;

  for (rel = relocs; rel < relend; rel ++)
    {
      reloc_howto_type *	   howto;
      unsigned long		   r_symndx;
      Elf_Internal_Sym *	   sym;
      asection *		   sec;
      struct elf_link_hash_entry * h;
      bfd_vma			   relocation;
      bfd_reloc_status_type	   r;
      const char *		   name = NULL;
      int			   r_type ATTRIBUTE_UNUSED;

      r_type = ELF32_R_TYPE (rel->r_info);
      r_symndx = ELF32_R_SYM (rel->r_info);
      howto  = epiphany_elf_howto_table + ELF32_R_TYPE (rel->r_info);
      h      = NULL;
      sym    = NULL;
      sec    = NULL;

      if (r_symndx < symtab_hdr->sh_info)
	{
	  sym = local_syms + r_symndx;
	  sec = local_sections [r_symndx];
	  relocation = BASEADDR (sec) + sym->st_value;

	  name = bfd_elf_string_from_elf_section
	    (input_bfd, symtab_hdr->sh_link, sym->st_name);
	  name = name == NULL ? bfd_section_name (sec) : name;
	}
      else
	{
	  bool warned ATTRIBUTE_UNUSED;
	  bool unresolved_reloc ATTRIBUTE_UNUSED;
	  bool ignored ATTRIBUTE_UNUSED;

	  RELOC_FOR_GLOBAL_SYMBOL (info, input_bfd, input_section, rel,
				   r_symndx, symtab_hdr, sym_hashes,
				   h, sec, relocation,
				   unresolved_reloc, warned, ignored);

	  name = h->root.root.string;
	}

      if (sec != NULL && discarded_section (sec))
	RELOC_AGAINST_DISCARDED_SECTION (info, input_bfd, input_section,
					 rel, 1, relend, howto, 0, contents);

      if (bfd_link_relocatable (info))
	continue;

      /* Finally, the sole EPIPHANY-specific part.  */
      r = epiphany_final_link_relocate (howto, input_bfd, input_section,
				     contents, rel, relocation);

      if (r != bfd_reloc_ok)
	{
	  const char * msg = NULL;

	  switch (r)
	    {
	    case bfd_reloc_overflow:
	      (*info->callbacks->reloc_overflow)
		(info, (h ? &h->root : NULL), name, howto->name,
		 (bfd_vma) 0, input_bfd, input_section, rel->r_offset);
	      break;

	    case bfd_reloc_undefined:
	      (*info->callbacks->undefined_symbol)
		(info, name, input_bfd, input_section, rel->r_offset, true);
	      break;

	    case bfd_reloc_outofrange:
	      msg = _("internal error: out of range error");
	      break;

	      /* This is how epiphany_final_link_relocate tells us of a
		 non-kosher reference between insn & data address spaces.  */
	    case bfd_reloc_notsupported:
	      if (sym != NULL) /* Only if it's not an unresolved symbol.  */
		 msg = _("unsupported relocation between data/insn address spaces");
	      break;

	    case bfd_reloc_dangerous:
	      msg = _("internal error: dangerous relocation");
	      break;

	    default:
	      msg = _("internal error: unknown error");
	      break;
	    }

	  if (msg)
	    (*info->callbacks->warning) (info, msg, name, input_bfd,
					 input_section, rel->r_offset);
	}
    }

  return true;
}

/* We only have a little-endian target.  */
#define TARGET_LITTLE_SYM	 epiphany_elf32_vec
#define TARGET_LITTLE_NAME  "elf32-epiphany"

#define ELF_ARCH	 bfd_arch_epiphany
#define ELF_MACHINE_CODE EM_ADAPTEVA_EPIPHANY

#define ELF_MAXPAGESIZE  0x8000 /* No pages on the EPIPHANY.  */

#define elf_info_to_howto_rel			NULL
#define elf_info_to_howto			epiphany_info_to_howto_rela

#define elf_backend_can_gc_sections		1
#define elf_backend_rela_normal			1
#define elf_backend_relocate_section		epiphany_elf_relocate_section

#define elf_symbol_leading_char			'_'
#define bfd_elf32_bfd_reloc_type_lookup		epiphany_reloc_type_lookup
#define bfd_elf32_bfd_reloc_name_lookup		epiphany_reloc_name_lookup
#define bfd_elf32_bfd_relax_section		epiphany_elf_relax_section

#include "elf32-target.h"