Subversion Repositories openrisc_2011-10-31

/* GDB routines for manipulating the minimal symbol tables.

   Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,

   2002, 2003, 2004, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.

   Contributed by Cygnus Support, using pieces from other GDB modules.

   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/>.  */

/* This file contains support routines for creating, manipulating, and

   destroying minimal symbol tables.

   Minimal symbol tables are used to hold some very basic information about

   all defined global symbols (text, data, bss, abs, etc).  The only two

   required pieces of information are the symbol's name and the address

   associated with that symbol.

   In many cases, even if a file was compiled with no special options for

   debugging at all, as long as was not stripped it will contain sufficient

   information to build useful minimal symbol tables using this structure.

   Even when a file contains enough debugging information to build a full

   symbol table, these minimal symbols are still useful for quickly mapping

   between names and addresses, and vice versa.  They are also sometimes used

   to figure out what full symbol table entries need to be read in. */

#include "defs.h"

#include <ctype.h>

#include "gdb_string.h"

#include "symtab.h"

#include "bfd.h"

#include "symfile.h"

#include "objfiles.h"

#include "demangle.h"

#include "value.h"

#include "cp-abi.h"

#include "target.h"

#include "cp-support.h"

#include "language.h"

/* Accumulate the minimal symbols for each objfile in bunches of BUNCH_SIZE.

   At the end, copy them all into one newly allocated location on an objfile's

   symbol obstack.  */

#define BUNCH_SIZE 127

struct msym_bunch

  {

    struct msym_bunch *next;

    struct minimal_symbol contents[BUNCH_SIZE];

  };

/* Bunch currently being filled up.

   The next field points to chain of filled bunches.  */

static struct msym_bunch *msym_bunch;

/* Number of slots filled in current bunch.  */

static int msym_bunch_index;

/* Total number of minimal symbols recorded so far for the objfile.  */

static int msym_count;

/* Compute a hash code based using the same criteria as `strcmp_iw'.  */

unsigned int

msymbol_hash_iw (const char *string)

{

  unsigned int hash = 0;

  while (*string && *string != '(')

    {

      while (isspace (*string))

        ++string;

      if (*string && *string != '(')

        {

          hash = hash * 67 + *string - 113;

          ++string;

        }

    }

  return hash;

}

/* Compute a hash code for a string.  */

unsigned int

msymbol_hash (const char *string)

{

  unsigned int hash = 0;

  for (; *string; ++string)

    hash = hash * 67 + *string - 113;

  return hash;

}

/* Add the minimal symbol SYM to an objfile's minsym hash table, TABLE.  */

void

add_minsym_to_hash_table (struct minimal_symbol *sym,

                          struct minimal_symbol **table)

{

  if (sym->hash_next == NULL)

    {

      unsigned int hash

        = msymbol_hash (SYMBOL_LINKAGE_NAME (sym)) % MINIMAL_SYMBOL_HASH_SIZE;

      sym->hash_next = table[hash];

      table[hash] = sym;

    }

}

/* Add the minimal symbol SYM to an objfile's minsym demangled hash table,

   TABLE.  */

static void

add_minsym_to_demangled_hash_table (struct minimal_symbol *sym,

                                  struct minimal_symbol **table)

{

  if (sym->demangled_hash_next == NULL)

    {

      unsigned int hash

        = msymbol_hash_iw (SYMBOL_SEARCH_NAME (sym)) % MINIMAL_SYMBOL_HASH_SIZE;

      sym->demangled_hash_next = table[hash];

      table[hash] = sym;

    }

}

/* Return OBJFILE where minimal symbol SYM is defined.  */

struct objfile *

msymbol_objfile (struct minimal_symbol *sym)

{

  struct objfile *objf;

  struct minimal_symbol *tsym;

  unsigned int hash

    = msymbol_hash (SYMBOL_LINKAGE_NAME (sym)) % MINIMAL_SYMBOL_HASH_SIZE;

  for (objf = object_files; objf; objf = objf->next)

    for (tsym = objf->msymbol_hash[hash]; tsym; tsym = tsym->hash_next)

      if (tsym == sym)

        return objf;

  /* We should always be able to find the objfile ...  */

  internal_error (__FILE__, __LINE__, _("failed internal consistency check"));

}

/* Look through all the current minimal symbol tables and find the

   first minimal symbol that matches NAME.  If OBJF is non-NULL, limit

   the search to that objfile.  If SFILE is non-NULL, the only file-scope

   symbols considered will be from that source file (global symbols are

   still preferred).  Returns a pointer to the minimal symbol that

   matches, or NULL if no match is found.

   Note:  One instance where there may be duplicate minimal symbols with

   the same name is when the symbol tables for a shared library and the

   symbol tables for an executable contain global symbols with the same

   names (the dynamic linker deals with the duplication).

   It's also possible to have minimal symbols with different mangled

   names, but identical demangled names.  For example, the GNU C++ v3

   ABI requires the generation of two (or perhaps three) copies of

   constructor functions --- "in-charge", "not-in-charge", and

   "allocate" copies; destructors may be duplicated as well.

   Obviously, there must be distinct mangled names for each of these,

   but the demangled names are all the same: S::S or S::~S.  */

struct minimal_symbol *

lookup_minimal_symbol (const char *name, const char *sfile,

                       struct objfile *objf)

{

  struct objfile *objfile;

  struct minimal_symbol *msymbol;

  struct minimal_symbol *found_symbol = NULL;

  struct minimal_symbol *found_file_symbol = NULL;

  struct minimal_symbol *trampoline_symbol = NULL;

  unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;

  unsigned int dem_hash = msymbol_hash_iw (name) % MINIMAL_SYMBOL_HASH_SIZE;

  int needtofreename = 0;

  const char *modified_name;

  if (sfile != NULL)

    {

      char *p = strrchr (sfile, '/');

      if (p != NULL)

        sfile = p + 1;

    }

  /* For C++, canonicalize the input name. */

  modified_name = name;

  if (current_language->la_language == language_cplus)

    {

      char *cname = cp_canonicalize_string (name);

      if (cname)

        {

          modified_name = cname;

          needtofreename = 1;

        }

    }

  for (objfile = object_files;

       objfile != NULL && found_symbol == NULL;

       objfile = objfile->next)

    {

      if (objf == NULL || objf == objfile

          || objf == objfile->separate_debug_objfile_backlink)

        {

          /* Do two passes: the first over the ordinary hash table,

             and the second over the demangled hash table.  */

        int pass;

        for (pass = 1; pass <= 2 && found_symbol == NULL; pass++)

            {

            /* Select hash list according to pass.  */

            if (pass == 1)

              msymbol = objfile->msymbol_hash[hash];

            else

              msymbol = objfile->msymbol_demangled_hash[dem_hash];

            while (msymbol != NULL && found_symbol == NULL)

                {

                  int match;

                  if (pass == 1)

                    {

                      match = strcmp (SYMBOL_LINKAGE_NAME (msymbol),

                                      modified_name) == 0;

                    }

                  else

                    {

                      match = SYMBOL_MATCHES_SEARCH_NAME (msymbol,

                                                          modified_name);

                    }

                  if (match)

                    {

                    switch (MSYMBOL_TYPE (msymbol))

                      {

                      case mst_file_text:

                      case mst_file_data:

                      case mst_file_bss:

                        if (sfile == NULL

                            || strcmp (msymbol->filename, sfile) == 0)

                          found_file_symbol = msymbol;

                        break;

                      case mst_solib_trampoline:

                        /* If a trampoline symbol is found, we prefer to

                           keep looking for the *real* symbol. If the

                           actual symbol is not found, then we'll use the

                           trampoline entry. */

                        if (trampoline_symbol == NULL)

                          trampoline_symbol = msymbol;

                        break;

                      case mst_unknown:

                      default:

                        found_symbol = msymbol;

                        break;

                      }

                    }

                /* Find the next symbol on the hash chain.  */

                if (pass == 1)

                  msymbol = msymbol->hash_next;

                else

                  msymbol = msymbol->demangled_hash_next;

                }

            }

        }

    }

  if (needtofreename)

    xfree ((void *) modified_name);

  /* External symbols are best.  */

  if (found_symbol)

    return found_symbol;

  /* File-local symbols are next best.  */

  if (found_file_symbol)

    return found_file_symbol;

  /* Symbols for shared library trampolines are next best.  */

  if (trampoline_symbol)

    return trampoline_symbol;

  return NULL;

}

/* Look through all the current minimal symbol tables and find the

   first minimal symbol that matches NAME and has text type.  If OBJF

   is non-NULL, limit the search to that objfile.  Returns a pointer

   to the minimal symbol that matches, or NULL if no match is found.

   This function only searches the mangled (linkage) names.  */

struct minimal_symbol *

lookup_minimal_symbol_text (const char *name, struct objfile *objf)

{

  struct objfile *objfile;

  struct minimal_symbol *msymbol;

  struct minimal_symbol *found_symbol = NULL;

  struct minimal_symbol *found_file_symbol = NULL;

  unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;

  for (objfile = object_files;

       objfile != NULL && found_symbol == NULL;

       objfile = objfile->next)

    {

      if (objf == NULL || objf == objfile

          || objf == objfile->separate_debug_objfile_backlink)

        {

          for (msymbol = objfile->msymbol_hash[hash];

               msymbol != NULL && found_symbol == NULL;

               msymbol = msymbol->hash_next)

            {

              if (strcmp (SYMBOL_LINKAGE_NAME (msymbol), name) == 0 &&

                  (MSYMBOL_TYPE (msymbol) == mst_text ||

                   MSYMBOL_TYPE (msymbol) == mst_file_text))

                {

                  switch (MSYMBOL_TYPE (msymbol))

                    {

                    case mst_file_text:

                      found_file_symbol = msymbol;

                      break;

                    default:

                      found_symbol = msymbol;

                      break;

                    }

                }

            }

        }

    }

  /* External symbols are best.  */

  if (found_symbol)

    return found_symbol;

  /* File-local symbols are next best.  */

  if (found_file_symbol)

    return found_file_symbol;

  return NULL;

}

/* Look through all the current minimal symbol tables and find the

   first minimal symbol that matches NAME and PC.  If OBJF is non-NULL,

   limit the search to that objfile.  Returns a pointer to the minimal

   symbol that matches, or NULL if no match is found.  */

struct minimal_symbol *

lookup_minimal_symbol_by_pc_name (CORE_ADDR pc, const char *name,

                                  struct objfile *objf)

{

  struct objfile *objfile;

  struct minimal_symbol *msymbol;

  unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;

  for (objfile = object_files;

       objfile != NULL;

       objfile = objfile->next)

    {

      if (objf == NULL || objf == objfile

          || objf == objfile->separate_debug_objfile_backlink)

        {

          for (msymbol = objfile->msymbol_hash[hash];

               msymbol != NULL;

               msymbol = msymbol->hash_next)

            {

              if (SYMBOL_VALUE_ADDRESS (msymbol) == pc

                  && strcmp (SYMBOL_LINKAGE_NAME (msymbol), name) == 0)

                return msymbol;

            }

        }

    }

  return NULL;

}

/* Look through all the current minimal symbol tables and find the

   first minimal symbol that matches NAME and is a solib trampoline.

   If OBJF is non-NULL, limit the search to that objfile.  Returns a

   pointer to the minimal symbol that matches, or NULL if no match is

   found.

   This function only searches the mangled (linkage) names.  */

struct minimal_symbol *

lookup_minimal_symbol_solib_trampoline (const char *name,

                                        struct objfile *objf)

{

  struct objfile *objfile;

  struct minimal_symbol *msymbol;

  struct minimal_symbol *found_symbol = NULL;

  unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;

  for (objfile = object_files;

       objfile != NULL && found_symbol == NULL;

       objfile = objfile->next)

    {

      if (objf == NULL || objf == objfile

          || objf == objfile->separate_debug_objfile_backlink)

        {

          for (msymbol = objfile->msymbol_hash[hash];

               msymbol != NULL && found_symbol == NULL;

               msymbol = msymbol->hash_next)

            {

              if (strcmp (SYMBOL_LINKAGE_NAME (msymbol), name) == 0 &&

                  MSYMBOL_TYPE (msymbol) == mst_solib_trampoline)

                return msymbol;

            }

        }

    }

  return NULL;

}

/* Search through the minimal symbol table for each objfile and find

   the symbol whose address is the largest address that is still less

   than or equal to PC, and matches SECTION (which is not NULL).

   Returns a pointer to the minimal symbol if such a symbol is found,

   or NULL if PC is not in a suitable range.

   Note that we need to look through ALL the minimal symbol tables

   before deciding on the symbol that comes closest to the specified PC.

   This is because objfiles can overlap, for example objfile A has .text

   at 0x100 and .data at 0x40000 and objfile B has .text at 0x234 and

   .data at 0x40048.

   If WANT_TRAMPOLINE is set, prefer mst_solib_trampoline symbols when

   there are text and trampoline symbols at the same address.

   Otherwise prefer mst_text symbols.  */

static struct minimal_symbol *

lookup_minimal_symbol_by_pc_section_1 (CORE_ADDR pc,

                                       struct obj_section *section,

                                       int want_trampoline)

{

  int lo;

  int hi;

  int new;

  struct objfile *objfile;

  struct minimal_symbol *msymbol;

  struct minimal_symbol *best_symbol = NULL;

  enum minimal_symbol_type want_type, other_type;

  want_type = want_trampoline ? mst_solib_trampoline : mst_text;

  other_type = want_trampoline ? mst_text : mst_solib_trampoline;

  /* We can not require the symbol found to be in section, because

     e.g. IRIX 6.5 mdebug relies on this code returning an absolute

     symbol - but find_pc_section won't return an absolute section and

     hence the code below would skip over absolute symbols.  We can

     still take advantage of the call to find_pc_section, though - the

     object file still must match.  In case we have separate debug

     files, search both the file and its separate debug file.  There's

     no telling which one will have the minimal symbols.  */

  gdb_assert (section != NULL);

  for (objfile = section->objfile;

       objfile != NULL;

       objfile = objfile_separate_debug_iterate (section->objfile, objfile))

    {

      /* If this objfile has a minimal symbol table, go search it using

         a binary search.  Note that a minimal symbol table always consists

         of at least two symbols, a "real" symbol and the terminating

         "null symbol".  If there are no real symbols, then there is no

         minimal symbol table at all. */

      if (objfile->minimal_symbol_count > 0)

        {

          int best_zero_sized = -1;

          msymbol = objfile->msymbols;

          lo = 0;

          hi = objfile->minimal_symbol_count - 1;

          /* This code assumes that the minimal symbols are sorted by

             ascending address values.  If the pc value is greater than or

             equal to the first symbol's address, then some symbol in this

             minimal symbol table is a suitable candidate for being the

             "best" symbol.  This includes the last real symbol, for cases

             where the pc value is larger than any address in this vector.

             By iterating until the address associated with the current

             hi index (the endpoint of the test interval) is less than

             or equal to the desired pc value, we accomplish two things:

             (1) the case where the pc value is larger than any minimal

             symbol address is trivially solved, (2) the address associated

             with the hi index is always the one we want when the interation

             terminates.  In essence, we are iterating the test interval

             down until the pc value is pushed out of it from the high end.

             Warning: this code is trickier than it would appear at first. */

          /* Should also require that pc is <= end of objfile.  FIXME! */

          if (pc >= SYMBOL_VALUE_ADDRESS (&msymbol[lo]))

            {

              while (SYMBOL_VALUE_ADDRESS (&msymbol[hi]) > pc)

                {

                  /* pc is still strictly less than highest address */

                  /* Note "new" will always be >= lo */

                  new = (lo + hi) / 2;

                  if ((SYMBOL_VALUE_ADDRESS (&msymbol[new]) >= pc) ||

                      (lo == new))

                    {

                      hi = new;

                    }

                  else

                    {

                      lo = new;

                    }

                }

              /* If we have multiple symbols at the same address, we want

                 hi to point to the last one.  That way we can find the

                 right symbol if it has an index greater than hi.  */

              while (hi < objfile->minimal_symbol_count - 1

                     && (SYMBOL_VALUE_ADDRESS (&msymbol[hi])

                         == SYMBOL_VALUE_ADDRESS (&msymbol[hi + 1])))

                hi++;

              /* Skip various undesirable symbols.  */

              while (hi >= 0)

                {

                  /* Skip any absolute symbols.  This is apparently

                     what adb and dbx do, and is needed for the CM-5.

                     There are two known possible problems: (1) on

                     ELF, apparently end, edata, etc. are absolute.

                     Not sure ignoring them here is a big deal, but if

                     we want to use them, the fix would go in

                     elfread.c.  (2) I think shared library entry

                     points on the NeXT are absolute.  If we want

                     special handling for this it probably should be

                     triggered by a special mst_abs_or_lib or some

                     such.  */

                  if (MSYMBOL_TYPE (&msymbol[hi]) == mst_abs)

                    {

                      hi--;

                      continue;

                    }

                  /* If SECTION was specified, skip any symbol from

                     wrong section.  */

                  if (section

                      /* Some types of debug info, such as COFF,

                         don't fill the bfd_section member, so don't

                         throw away symbols on those platforms.  */

                      && SYMBOL_OBJ_SECTION (&msymbol[hi]) != NULL

                      && (!matching_obj_sections

                          (SYMBOL_OBJ_SECTION (&msymbol[hi]), section)))

                    {

                      hi--;

                      continue;

                    }

                  /* If we are looking for a trampoline and this is a

                     text symbol, or the other way around, check the

                     preceeding symbol too.  If they are otherwise

                     identical prefer that one.  */

                  if (hi > 0

                      && MSYMBOL_TYPE (&msymbol[hi]) == other_type

                      && MSYMBOL_TYPE (&msymbol[hi - 1]) == want_type

                      && (MSYMBOL_SIZE (&msymbol[hi])

                          == MSYMBOL_SIZE (&msymbol[hi - 1]))

                      && (SYMBOL_VALUE_ADDRESS (&msymbol[hi])

                          == SYMBOL_VALUE_ADDRESS (&msymbol[hi - 1]))

                      && (SYMBOL_OBJ_SECTION (&msymbol[hi])

                          == SYMBOL_OBJ_SECTION (&msymbol[hi - 1])))

                    {

                      hi--;

                      continue;

                    }

                  /* If the minimal symbol has a zero size, save it

                     but keep scanning backwards looking for one with

                     a non-zero size.  A zero size may mean that the

                     symbol isn't an object or function (e.g. a

                     label), or it may just mean that the size was not

                     specified.  */

                  if (MSYMBOL_SIZE (&msymbol[hi]) == 0

                      && best_zero_sized == -1)

                    {

                      best_zero_sized = hi;

                      hi--;

                      continue;

                    }

                  /* If we are past the end of the current symbol, try

                     the previous symbol if it has a larger overlapping

                     size.  This happens on i686-pc-linux-gnu with glibc;

                     the nocancel variants of system calls are inside

                     the cancellable variants, but both have sizes.  */

                  if (hi > 0

                      && MSYMBOL_SIZE (&msymbol[hi]) != 0

                      && pc >= (SYMBOL_VALUE_ADDRESS (&msymbol[hi])

                                + MSYMBOL_SIZE (&msymbol[hi]))

                      && pc < (SYMBOL_VALUE_ADDRESS (&msymbol[hi - 1])

                               + MSYMBOL_SIZE (&msymbol[hi - 1])))

                    {

                      hi--;

                      continue;

                    }

                  /* Otherwise, this symbol must be as good as we're going

                     to get.  */

                  break;

                }

              /* If HI has a zero size, and best_zero_sized is set,

                 then we had two or more zero-sized symbols; prefer

                 the first one we found (which may have a higher

                 address).  Also, if we ran off the end, be sure

                 to back up.  */

              if (best_zero_sized != -1

                  && (hi < 0 || MSYMBOL_SIZE (&msymbol[hi]) == 0))

                hi = best_zero_sized;

              /* If the minimal symbol has a non-zero size, and this

                 PC appears to be outside the symbol's contents, then

                 refuse to use this symbol.  If we found a zero-sized

                 symbol with an address greater than this symbol's,

                 use that instead.  We assume that if symbols have

                 specified sizes, they do not overlap.  */

              if (hi >= 0

                  && MSYMBOL_SIZE (&msymbol[hi]) != 0

                  && pc >= (SYMBOL_VALUE_ADDRESS (&msymbol[hi])

                            + MSYMBOL_SIZE (&msymbol[hi])))

                {

                  if (best_zero_sized != -1)

                    hi = best_zero_sized;

                  else

                    /* Go on to the next object file.  */

                    continue;

                }

              /* The minimal symbol indexed by hi now is the best one in this

                 objfile's minimal symbol table.  See if it is the best one

                 overall. */

              if (hi >= 0

                  && ((best_symbol == NULL) ||

                      (SYMBOL_VALUE_ADDRESS (best_symbol) <

                       SYMBOL_VALUE_ADDRESS (&msymbol[hi]))))

                {

                  best_symbol = &msymbol[hi];

                }

            }

        }

    }

  return (best_symbol);

}

struct minimal_symbol *

lookup_minimal_symbol_by_pc_section (CORE_ADDR pc, struct obj_section *section)

{

  if (section == NULL)

    {

      /* NOTE: cagney/2004-01-27: This was using find_pc_mapped_section to

         force the section but that (well unless you're doing overlay

         debugging) always returns NULL making the call somewhat useless.  */

      section = find_pc_section (pc);

      if (section == NULL)

        return NULL;

    }

  return lookup_minimal_symbol_by_pc_section_1 (pc, section, 0);

}

/* Backward compatibility: search through the minimal symbol table

   for a matching PC (no section given) */

struct minimal_symbol *

lookup_minimal_symbol_by_pc (CORE_ADDR pc)

{

  return lookup_minimal_symbol_by_pc_section (pc, NULL);

}

/* Find the minimal symbol named NAME, and return both the minsym

   struct and its objfile.  This only checks the linkage name.  Sets

   *OBJFILE_P and returns the minimal symbol, if it is found.  If it

   is not found, returns NULL.  */

struct minimal_symbol *

lookup_minimal_symbol_and_objfile (const char *name,

                                   struct objfile **objfile_p)

{

  struct objfile *objfile;

  unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;

  ALL_OBJFILES (objfile)

    {

      struct minimal_symbol *msym;

      for (msym = objfile->msymbol_hash[hash];

           msym != NULL;

           msym = msym->hash_next)

        {

          if (strcmp (SYMBOL_LINKAGE_NAME (msym), name) == 0)

            {

              *objfile_p = objfile;

              return msym;

            }

        }

    }

  return 0;

}