gdb/compile/compile-object-load.c

/* Load module for 'compile' command.

   Copyright (C) 2014-2015 Free Software Foundation, Inc.

   This file is part of GDB.

   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, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "compile-object-load.h"
#include "compile-internal.h"
#include "command.h"
#include "objfiles.h"
#include "gdbcore.h"
#include "readline/tilde.h"
#include "bfdlink.h"
#include "gdbcmd.h"
#include "regcache.h"
#include "inferior.h"
#include "compile.h"
#include "arch-utils.h"

/* Helper data for setup_sections.  */

struct setup_sections_data
{
  /* Size of all recent sections with matching LAST_PROT.  */
  CORE_ADDR last_size;

  /* First section matching LAST_PROT.  */
  asection *last_section_first;

  /* Memory protection like the prot parameter of gdbarch_infcall_mmap. */
  unsigned last_prot;

  /* Maximum of alignments of all sections matching LAST_PROT.
     This value is always at least 1.  This value is always a power of 2.  */
  CORE_ADDR last_max_alignment;
};

/* Place all ABFD sections next to each other obeying all constraints.  */

static void
setup_sections (bfd *abfd, asection *sect, void *data_voidp)
{
  struct setup_sections_data *data = data_voidp;
  CORE_ADDR alignment;
  unsigned prot;

  if (sect != NULL)
    {
      /* It is required by later bfd_get_relocated_section_contents.  */
      if (sect->output_section == NULL)
	sect->output_section = sect;

      if ((bfd_get_section_flags (abfd, sect) & SEC_ALLOC) == 0)
	return;

      // Make the memory always readable.
      prot = GDB_MMAP_PROT_READ;
      if ((bfd_get_section_flags (abfd, sect) & SEC_READONLY) == 0)
	prot |= GDB_MMAP_PROT_WRITE;
      if ((bfd_get_section_flags (abfd, sect) & SEC_CODE) != 0)
	prot |= GDB_MMAP_PROT_EXEC;

      if (compile_debug)
	fprintf_unfiltered (gdb_stdout,
			    "module \"%s\" section \"%s\" size %s prot %u\n",
			    bfd_get_filename (abfd),
			    bfd_get_section_name (abfd, sect),
			    paddress (target_gdbarch (),
				      bfd_get_section_size (sect)),
			    prot);
    }
  else
    prot = -1;

  if (sect == NULL
      || (data->last_prot != prot && bfd_get_section_size (sect) != 0))
    {
      CORE_ADDR addr;
      asection *sect_iter;

      if (data->last_size != 0)
	{
	  addr = gdbarch_infcall_mmap (target_gdbarch (), data->last_size,
				       data->last_prot);
	  if (compile_debug)
	    fprintf_unfiltered (gdb_stdout,
				"allocated %s bytes at %s prot %u\n",
				paddress (target_gdbarch (), data->last_size),
				paddress (target_gdbarch (), addr),
				data->last_prot);
	}
      else
	addr = 0;

      if ((addr & (data->last_max_alignment - 1)) != 0)
	error (_("Inferior compiled module address %s "
		 "is not aligned to BFD required %s."),
	       paddress (target_gdbarch (), addr),
	       paddress (target_gdbarch (), data->last_max_alignment));

      for (sect_iter = data->last_section_first; sect_iter != sect;
	   sect_iter = sect_iter->next)
	if ((bfd_get_section_flags (abfd, sect_iter) & SEC_ALLOC) != 0)
	  bfd_set_section_vma (abfd, sect_iter,
			       addr + bfd_get_section_vma (abfd, sect_iter));

      data->last_size = 0;
      data->last_section_first = sect;
      data->last_prot = prot;
      data->last_max_alignment = 1;
    }

  if (sect == NULL)
    return;

  alignment = ((CORE_ADDR) 1) << bfd_get_section_alignment (abfd, sect);
  data->last_max_alignment = max (data->last_max_alignment, alignment);

  data->last_size = (data->last_size + alignment - 1) & -alignment;

  bfd_set_section_vma (abfd, sect, data->last_size);

  data->last_size += bfd_get_section_size (sect);
  data->last_size = (data->last_size + alignment - 1) & -alignment;
}

/* Helper for link_callbacks callbacks vector.  */

static bfd_boolean
link_callbacks_multiple_definition (struct bfd_link_info *link_info,
				    struct bfd_link_hash_entry *h, bfd *nbfd,
				    asection *nsec, bfd_vma nval)
{
  bfd *abfd = link_info->input_bfds;

  if (link_info->allow_multiple_definition)
    return TRUE;
  warning (_("Compiled module \"%s\": multiple symbol definitions: %s"),
	   bfd_get_filename (abfd), h->root.string);
  return FALSE;
}

/* Helper for link_callbacks callbacks vector.  */

static bfd_boolean
link_callbacks_warning (struct bfd_link_info *link_info, const char *xwarning,
                        const char *symbol, bfd *abfd, asection *section,
			bfd_vma address)
{
  warning (_("Compiled module \"%s\" section \"%s\": warning: %s"),
	   bfd_get_filename (abfd), bfd_get_section_name (abfd, section),
	   xwarning);
  /* Maybe permit running as a module?  */
  return FALSE;
}

/* Helper for link_callbacks callbacks vector.  */

static bfd_boolean
link_callbacks_undefined_symbol (struct bfd_link_info *link_info,
				 const char *name, bfd *abfd, asection *section,
				 bfd_vma address, bfd_boolean is_fatal)
{
  warning (_("Cannot resolve relocation to \"%s\" "
	     "from compiled module \"%s\" section \"%s\"."),
	   name, bfd_get_filename (abfd), bfd_get_section_name (abfd, section));
  return FALSE;
}

/* Helper for link_callbacks callbacks vector.  */

static bfd_boolean
link_callbacks_reloc_overflow (struct bfd_link_info *link_info,
			       struct bfd_link_hash_entry *entry,
			       const char *name, const char *reloc_name,
			       bfd_vma addend, bfd *abfd, asection *section,
			       bfd_vma address)
{
  /* TRUE is required for intra-module relocations.  */
  return TRUE;
}

/* Helper for link_callbacks callbacks vector.  */

static bfd_boolean
link_callbacks_reloc_dangerous (struct bfd_link_info *link_info,
				const char *message, bfd *abfd,
				asection *section, bfd_vma address)
{
  warning (_("Compiled module \"%s\" section \"%s\": dangerous "
	     "relocation: %s\n"),
	   bfd_get_filename (abfd), bfd_get_section_name (abfd, section),
	   message);
  return FALSE;
}

/* Helper for link_callbacks callbacks vector.  */

static bfd_boolean
link_callbacks_unattached_reloc (struct bfd_link_info *link_info,
				 const char *name, bfd *abfd, asection *section,
				 bfd_vma address)
{
  warning (_("Compiled module \"%s\" section \"%s\": unattached "
	     "relocation: %s\n"),
	   bfd_get_filename (abfd), bfd_get_section_name (abfd, section),
	   name);
  return FALSE;
}

/* Helper for link_callbacks callbacks vector.  */

static void
link_callbacks_einfo (const char *fmt, ...)
{
  struct cleanup *cleanups;
  va_list ap;
  char *str;

  va_start (ap, fmt);
  str = xstrvprintf (fmt, ap);
  va_end (ap);
  cleanups = make_cleanup (xfree, str);

  warning (_("Compile module: warning: %s"), str);

  do_cleanups (cleanups);
}

/* Helper for bfd_get_relocated_section_contents.
   Only these symbols are set by bfd_simple_get_relocated_section_contents
   but bfd/ seems to use even the NULL ones without checking them first.  */

static const struct bfd_link_callbacks link_callbacks =
{
  NULL, /* add_archive_element */
  link_callbacks_multiple_definition, /* multiple_definition */
  NULL, /* multiple_common */
  NULL, /* add_to_set */
  NULL, /* constructor */
  link_callbacks_warning, /* warning */
  link_callbacks_undefined_symbol, /* undefined_symbol */
  link_callbacks_reloc_overflow, /* reloc_overflow */
  link_callbacks_reloc_dangerous, /* reloc_dangerous */
  link_callbacks_unattached_reloc, /* unattached_reloc */
  NULL, /* notice */
  link_callbacks_einfo, /* einfo */
  NULL, /* info */
  NULL, /* minfo */
  NULL, /* override_segment_assignment */
};

struct link_hash_table_cleanup_data
{
  bfd *abfd;
  bfd *link_next;
};

/* Cleanup callback for struct bfd_link_info.  */

static void
link_hash_table_free (void *d)
{
  struct link_hash_table_cleanup_data *data = d;

  if (data->abfd->is_linker_output)
    (*data->abfd->link.hash->hash_table_free) (data->abfd);
  data->abfd->link.next = data->link_next;
}

/* Relocate and store into inferior memory each section SECT of ABFD.  */

static void
copy_sections (bfd *abfd, asection *sect, void *data)
{
  asymbol **symbol_table = data;
  bfd_byte *sect_data, *sect_data_got;
  struct cleanup *cleanups;
  struct bfd_link_info link_info;
  struct bfd_link_order link_order;
  CORE_ADDR inferior_addr;
  struct link_hash_table_cleanup_data cleanup_data;

  if ((bfd_get_section_flags (abfd, sect) & (SEC_ALLOC | SEC_LOAD))
      != (SEC_ALLOC | SEC_LOAD))
    return;

  if (bfd_get_section_size (sect) == 0)
    return;

  /* Mostly a copy of bfd_simple_get_relocated_section_contents which GDB
     cannot use as it does not report relocations to undefined symbols.  */
  memset (&link_info, 0, sizeof (link_info));
  link_info.output_bfd = abfd;
  link_info.input_bfds = abfd;
  link_info.input_bfds_tail = &abfd->link.next;

  cleanup_data.abfd = abfd;
  cleanup_data.link_next = abfd->link.next;

  abfd->link.next = NULL;
  link_info.hash = bfd_link_hash_table_create (abfd);

  cleanups = make_cleanup (link_hash_table_free, &cleanup_data);
  link_info.callbacks = &link_callbacks;

  memset (&link_order, 0, sizeof (link_order));
  link_order.next = NULL;
  link_order.type = bfd_indirect_link_order;
  link_order.offset = 0;
  link_order.size = bfd_get_section_size (sect);
  link_order.u.indirect.section = sect;

  sect_data = xmalloc (bfd_get_section_size (sect));
  make_cleanup (xfree, sect_data);

  sect_data_got = bfd_get_relocated_section_contents (abfd, &link_info,
						      &link_order, sect_data,
						      FALSE, symbol_table);

  if (sect_data_got == NULL)
    error (_("Cannot map compiled module \"%s\" section \"%s\": %s"),
	   bfd_get_filename (abfd), bfd_get_section_name (abfd, sect),
	   bfd_errmsg (bfd_get_error ()));
  gdb_assert (sect_data_got == sect_data);

  inferior_addr = bfd_get_section_vma (abfd, sect);
  if (0 != target_write_memory (inferior_addr, sect_data,
				bfd_get_section_size (sect)))
    error (_("Cannot write compiled module \"%s\" section \"%s\" "
	     "to inferior memory range %s-%s."),
	   bfd_get_filename (abfd), bfd_get_section_name (abfd, sect),
	   paddress (target_gdbarch (), inferior_addr),
	   paddress (target_gdbarch (),
		     inferior_addr + bfd_get_section_size (sect)));

  do_cleanups (cleanups);
}

/* Fetch the type of first parameter of GCC_FE_WRAPPER_FUNCTION.
   Return NULL if GCC_FE_WRAPPER_FUNCTION has no parameters.
   Throw an error otherwise.  */

static struct type *
get_regs_type (struct objfile *objfile)
{
  struct symbol *func_sym;
  struct type *func_type, *regsp_type, *regs_type;

  func_sym = lookup_global_symbol_from_objfile (objfile,
						GCC_FE_WRAPPER_FUNCTION,
						VAR_DOMAIN);
  if (func_sym == NULL)
    error (_("Cannot find function \"%s\" in compiled module \"%s\"."),
	   GCC_FE_WRAPPER_FUNCTION, objfile_name (objfile));

  func_type = SYMBOL_TYPE (func_sym);
  if (TYPE_CODE (func_type) != TYPE_CODE_FUNC)
    error (_("Invalid type code %d of function \"%s\" in compiled "
	     "module \"%s\"."),
	   TYPE_CODE (func_type), GCC_FE_WRAPPER_FUNCTION,
	   objfile_name (objfile));

  /* No register parameter present.  */
  if (TYPE_NFIELDS (func_type) == 0)
    return NULL;

  if (TYPE_NFIELDS (func_type) != 1)
    error (_("Invalid %d parameters of function \"%s\" in compiled "
	     "module \"%s\"."),
	   TYPE_NFIELDS (func_type), GCC_FE_WRAPPER_FUNCTION,
	   objfile_name (objfile));

  regsp_type = check_typedef (TYPE_FIELD_TYPE (func_type, 0));
  if (TYPE_CODE (regsp_type) != TYPE_CODE_PTR)
    error (_("Invalid type code %d of first parameter of function \"%s\" "
	     "in compiled module \"%s\"."),
	   TYPE_CODE (regsp_type), GCC_FE_WRAPPER_FUNCTION,
	   objfile_name (objfile));

  regs_type = check_typedef (TYPE_TARGET_TYPE (regsp_type));
  if (TYPE_CODE (regs_type) != TYPE_CODE_STRUCT)
    error (_("Invalid type code %d of dereferenced first parameter "
	     "of function \"%s\" in compiled module \"%s\"."),
	   TYPE_CODE (regs_type), GCC_FE_WRAPPER_FUNCTION,
	   objfile_name (objfile));

  return regs_type;
}

/* Store all inferior registers required by REGS_TYPE to inferior memory
   starting at inferior address REGS_BASE.  */

static void
store_regs (struct type *regs_type, CORE_ADDR regs_base)
{
  struct gdbarch *gdbarch = target_gdbarch ();
  struct regcache *regcache = get_thread_regcache (inferior_ptid);
  int fieldno;

  for (fieldno = 0; fieldno < TYPE_NFIELDS (regs_type); fieldno++)
    {
      const char *reg_name = TYPE_FIELD_NAME (regs_type, fieldno);
      ULONGEST reg_bitpos = TYPE_FIELD_BITPOS (regs_type, fieldno);
      ULONGEST reg_bitsize = TYPE_FIELD_BITSIZE (regs_type, fieldno);
      ULONGEST reg_offset;
      struct type *reg_type = check_typedef (TYPE_FIELD_TYPE (regs_type,
							      fieldno));
      ULONGEST reg_size = TYPE_LENGTH (reg_type);
      int regnum;
      struct value *regval;
      CORE_ADDR inferior_addr;

      if (strcmp (reg_name, COMPILE_I_SIMPLE_REGISTER_DUMMY) == 0)
	continue;

      if ((reg_bitpos % 8) != 0 || reg_bitsize != 0)
	error (_("Invalid register \"%s\" position %s bits or size %s bits"),
	       reg_name, pulongest (reg_bitpos), pulongest (reg_bitsize));
      reg_offset = reg_bitpos / 8;

      if (TYPE_CODE (reg_type) != TYPE_CODE_INT
	  && TYPE_CODE (reg_type) != TYPE_CODE_PTR)
	error (_("Invalid register \"%s\" type code %d"), reg_name,
	       TYPE_CODE (reg_type));

      regnum = compile_register_name_demangle (gdbarch, reg_name);

      regval = value_from_register (reg_type, regnum, get_current_frame ());
      if (value_optimized_out (regval))
	error (_("Register \"%s\" is optimized out."), reg_name);
      if (!value_entirely_available (regval))
	error (_("Register \"%s\" is not available."), reg_name);

      inferior_addr = regs_base + reg_offset;
      if (0 != target_write_memory (inferior_addr, value_contents (regval),
				    reg_size))
	error (_("Cannot write register \"%s\" to inferior memory at %s."),
	       reg_name, paddress (gdbarch, inferior_addr));
    }
}

/* Load OBJECT_FILE into inferior memory.  Throw an error otherwise.
   Caller must fully dispose the return value by calling compile_object_run.
   SOURCE_FILE's copy is stored into the returned object.
   Caller should free both OBJECT_FILE and SOURCE_FILE immediatelly after this
   function returns.  */

struct compile_module *
compile_object_load (const char *object_file, const char *source_file)
{
  struct cleanup *cleanups, *cleanups_free_objfile;
  bfd *abfd;
  struct setup_sections_data setup_sections_data;
  CORE_ADDR addr, func_addr, regs_addr;
  struct bound_minimal_symbol bmsym;
  long storage_needed;
  asymbol **symbol_table, **symp;
  long number_of_symbols, missing_symbols;
  struct type *dptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
  unsigned dptr_type_len = TYPE_LENGTH (dptr_type);
  struct compile_module *retval;
  struct type *regs_type;
  char *filename, **matching;
  struct objfile *objfile;

  filename = tilde_expand (object_file);
  cleanups = make_cleanup (xfree, filename);

  abfd = gdb_bfd_open (filename, gnutarget, -1);
  if (abfd == NULL)
    error (_("\"%s\": could not open as compiled module: %s"),
          filename, bfd_errmsg (bfd_get_error ()));
  make_cleanup_bfd_unref (abfd);

  if (!bfd_check_format_matches (abfd, bfd_object, &matching))
    error (_("\"%s\": not in loadable format: %s"),
          filename, gdb_bfd_errmsg (bfd_get_error (), matching));

  if ((bfd_get_file_flags (abfd) & (EXEC_P | DYNAMIC)) != 0)
    error (_("\"%s\": not in object format."), filename);

  setup_sections_data.last_size = 0;
  setup_sections_data.last_section_first = abfd->sections;
  setup_sections_data.last_prot = -1;
  setup_sections_data.last_max_alignment = 1;
  bfd_map_over_sections (abfd, setup_sections, &setup_sections_data);
  setup_sections (abfd, NULL, &setup_sections_data);

  storage_needed = bfd_get_symtab_upper_bound (abfd);
  if (storage_needed < 0)
    error (_("Cannot read symbols of compiled module \"%s\": %s"),
          filename, bfd_errmsg (bfd_get_error ()));

  /* SYMFILE_VERBOSE is not passed even if FROM_TTY, user is not interested in
     "Reading symbols from ..." message for automatically generated file.  */
  objfile = symbol_file_add_from_bfd (abfd, filename, 0, NULL, 0, NULL);
  cleanups_free_objfile = make_cleanup_free_objfile (objfile);

  bmsym = lookup_minimal_symbol_text (GCC_FE_WRAPPER_FUNCTION, objfile);
  if (bmsym.minsym == NULL || MSYMBOL_TYPE (bmsym.minsym) == mst_file_text)
    error (_("Could not find symbol \"%s\" of compiled module \"%s\"."),
	   GCC_FE_WRAPPER_FUNCTION, filename);
  func_addr = BMSYMBOL_VALUE_ADDRESS (bmsym);

  /* The memory may be later needed
     by bfd_generic_get_relocated_section_contents
     called from default_symfile_relocate.  */
  symbol_table = obstack_alloc (&objfile->objfile_obstack, storage_needed);
  number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);
  if (number_of_symbols < 0)
    error (_("Cannot parse symbols of compiled module \"%s\": %s"),
          filename, bfd_errmsg (bfd_get_error ()));

  missing_symbols = 0;
  for (symp = symbol_table; symp < symbol_table + number_of_symbols; symp++)
    {
      asymbol *sym = *symp;

      if (sym->flags != 0)
	continue;
      if (compile_debug)
	fprintf_unfiltered (gdb_stdout,
			    "lookup undefined ELF symbol \"%s\"\n",
			    sym->name);
      sym->flags = BSF_GLOBAL;
      sym->section = bfd_abs_section_ptr;
      if (strcmp (sym->name, "_GLOBAL_OFFSET_TABLE_") == 0)
	{
	  sym->value = 0;
	  continue;
	}
      bmsym = lookup_minimal_symbol (sym->name, NULL, NULL);
      switch (bmsym.minsym == NULL
	      ? mst_unknown : MSYMBOL_TYPE (bmsym.minsym))
	{
	case mst_text:
	  sym->value = BMSYMBOL_VALUE_ADDRESS (bmsym);
	  break;
	default:
	  warning (_("Could not find symbol \"%s\" "
		     "for compiled module \"%s\"."),
		   sym->name, filename);
	  missing_symbols++;
	}
    }
  if (missing_symbols)
    error (_("%ld symbols were missing, cannot continue."), missing_symbols);

  bfd_map_over_sections (abfd, copy_sections, symbol_table);

  regs_type = get_regs_type (objfile);
  if (regs_type == NULL)
    regs_addr = 0;
  else
    {
      /* Use read-only non-executable memory protection.  */
      regs_addr = gdbarch_infcall_mmap (target_gdbarch (),
					TYPE_LENGTH (regs_type),
					GDB_MMAP_PROT_READ);
      gdb_assert (regs_addr != 0);
      store_regs (regs_type, regs_addr);
    }

  discard_cleanups (cleanups_free_objfile);
  do_cleanups (cleanups);

  retval = xmalloc (sizeof (*retval));
  retval->objfile = objfile;
  retval->source_file = xstrdup (source_file);
  retval->func_addr = func_addr;
  retval->regs_addr = regs_addr;
  return retval;
}