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 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"

/* 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_DEMANGLED_NAME (sym)) % MINIMAL_SYMBOL_HASH_SIZE;

      sym->demangled_hash_next = table[hash];

      table[hash] = sym;

    }

}

/* 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;

  if (sfile != NULL)

    {

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

      if (p != NULL)

        sfile = p + 1;

    }

  for (objfile = object_files;

       objfile != NULL && found_symbol == NULL;

       objfile = objfile->next)

    {

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

          || objf->separate_debug_objfile == objfile)

        {

          /* 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)

                {

                  /* FIXME: carlton/2003-02-27: This is an unholy

                     mixture of linkage names and natural names.  If

                     you want to test the linkage names with strcmp,

                     do that.  If you want to test the natural names

                     with strcmp_iw, use SYMBOL_MATCHES_NATURAL_NAME.  */

                  if (strcmp (DEPRECATED_SYMBOL_NAME (msymbol), (name)) == 0

                      || (SYMBOL_DEMANGLED_NAME (msymbol) != NULL

                          && strcmp_iw (SYMBOL_DEMANGLED_NAME (msymbol),

                                        (name)) == 0))

                    {

                    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;

                }

            }

        }

    }

  /* 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->separate_debug_objfile == objfile)

        {

          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 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->separate_debug_objfile == objfile)

        {

          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 (if non-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.  */

struct minimal_symbol *

lookup_minimal_symbol_by_pc_section (CORE_ADDR pc, asection *section)

{

  int lo;

  int hi;

  int new;

  struct objfile *objfile;

  struct minimal_symbol *msymbol;

  struct minimal_symbol *best_symbol = NULL;

  struct obj_section *pc_section;

  /* PC has to be in a known section.  This ensures that anything

     beyond the end of the last segment doesn't appear to be part of

     the last function in the last segment.  */

  pc_section = find_pc_section (pc);

  if (pc_section == NULL)

    return NULL;

  /* We can not require the symbol found to be in pc_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.  */

  objfile = pc_section->objfile;

  if (objfile->separate_debug_objfile)

    objfile = objfile->separate_debug_objfile;

  for (; objfile != NULL; objfile = objfile->separate_debug_objfile_backlink)

    {

      /* 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[hi].type == 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_BFD_SECTION (&msymbol[hi]) != NULL

                      && (!matching_bfd_sections

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

                    {

                      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);

}

/* 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)

{

  /* 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.  */

  struct obj_section *section = find_pc_section (pc);

  if (section == NULL)

    return NULL;

  return lookup_minimal_symbol_by_pc_section (pc, section->the_bfd_section);

}

/* Return leading symbol character for a BFD. If BFD is NULL,

   return the leading symbol character from the main objfile.  */

static int get_symbol_leading_char (bfd *);

static int

get_symbol_leading_char (bfd *abfd)

{

  if (abfd != NULL)

    return bfd_get_symbol_leading_char (abfd);

  if (symfile_objfile != NULL && symfile_objfile->obfd != NULL)

    return bfd_get_symbol_leading_char (symfile_objfile->obfd);

  return 0;

}

/* Prepare to start collecting minimal symbols.  Note that presetting

   msym_bunch_index to BUNCH_SIZE causes the first call to save a minimal

   symbol to allocate the memory for the first bunch. */

void

init_minimal_symbol_collection (void)

{

  msym_count = 0;

  msym_bunch = NULL;

  msym_bunch_index = BUNCH_SIZE;

}

void

prim_record_minimal_symbol (const char *name, CORE_ADDR address,

                            enum minimal_symbol_type ms_type,

                            struct objfile *objfile)

{

  int section;

  switch (ms_type)

    {

    case mst_text:

    case mst_file_text:

    case mst_solib_trampoline:

      section = SECT_OFF_TEXT (objfile);

      break;

    case mst_data:

    case mst_file_data:

      section = SECT_OFF_DATA (objfile);

      break;

    case mst_bss:

    case mst_file_bss:

      section = SECT_OFF_BSS (objfile);

      break;

    default:

      section = -1;

    }

  prim_record_minimal_symbol_and_info (name, address, ms_type,

                                       NULL, section, NULL, objfile);

}

/* Record a minimal symbol in the msym bunches.  Returns the symbol

   newly created.  */

struct minimal_symbol *

prim_record_minimal_symbol_and_info (const char *name, CORE_ADDR address,

                                     enum minimal_symbol_type ms_type,

                                     char *info, int section,

                                     asection *bfd_section,

                                     struct objfile *objfile)

{

  struct msym_bunch *new;

  struct minimal_symbol *msymbol;

  /* Don't put gcc_compiled, __gnu_compiled_cplus, and friends into

     the minimal symbols, because if there is also another symbol

     at the same address (e.g. the first function of the file),

     lookup_minimal_symbol_by_pc would have no way of getting the

     right one.  */

  if (ms_type == mst_file_text && name[0] == 'g'

      && (strcmp (name, GCC_COMPILED_FLAG_SYMBOL) == 0

          || strcmp (name, GCC2_COMPILED_FLAG_SYMBOL) == 0))

    return (NULL);

  /* It's safe to strip the leading char here once, since the name

     is also stored stripped in the minimal symbol table. */

  if (name[0] == get_symbol_leading_char (objfile->obfd))

    ++name;

  if (ms_type == mst_file_text && strncmp (name, "__gnu_compiled", 14) == 0)

    return (NULL);

  if (msym_bunch_index == BUNCH_SIZE)

    {

      new = (struct msym_bunch *) xmalloc (sizeof (struct msym_bunch));

      msym_bunch_index = 0;

      new->next = msym_bunch;

      msym_bunch = new;

    }

  msymbol = &msym_bunch->contents[msym_bunch_index];

  SYMBOL_INIT_LANGUAGE_SPECIFIC (msymbol, language_unknown);

  SYMBOL_LANGUAGE (msymbol) = language_auto;

  SYMBOL_SET_NAMES (msymbol, (char *)name, strlen (name), objfile);

  SYMBOL_VALUE_ADDRESS (msymbol) = address;

  SYMBOL_SECTION (msymbol) = section;

  SYMBOL_BFD_SECTION (msymbol) = bfd_section;

  MSYMBOL_TYPE (msymbol) = ms_type;

  /* FIXME:  This info, if it remains, needs its own field.  */

  MSYMBOL_INFO (msymbol) = info;        /* FIXME! */

  MSYMBOL_SIZE (msymbol) = 0;

  /* The hash pointers must be cleared! If they're not,

     add_minsym_to_hash_table will NOT add this msymbol to the hash table. */

  msymbol->hash_next = NULL;

  msymbol->demangled_hash_next = NULL;

  msym_bunch_index++;

  msym_count++;

  OBJSTAT (objfile, n_minsyms++);

  return msymbol;

}

/* Compare two minimal symbols by address and return a signed result based

   on unsigned comparisons, so that we sort into unsigned numeric order.

   Within groups with the same address, sort by name.  */

static int

compare_minimal_symbols (const void *fn1p, const void *fn2p)

{

  const struct minimal_symbol *fn1;

  const struct minimal_symbol *fn2;

  fn1 = (const struct minimal_symbol *) fn1p;

  fn2 = (const struct minimal_symbol *) fn2p;

  if (SYMBOL_VALUE_ADDRESS (fn1) < SYMBOL_VALUE_ADDRESS (fn2))

    {

      return (-1);              /* addr 1 is less than addr 2 */

    }

  else if (SYMBOL_VALUE_ADDRESS (fn1) > SYMBOL_VALUE_ADDRESS (fn2))

    {