import gdb-1999-08-23 snapshot

1 files changed, 1327 insertions, 0 deletions

diff --git a/gdb/pa64solib.c b/gdb/pa64solib.c
new file mode 100644
index 0000000..aa11f24
--- /dev/null
+++ b/gdb/pa64solib.c
@@ -0,0 +1,1327 @@
+/* Handle HP ELF shared libraries for GDB, the GNU Debugger.
+   Copyright 1999 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 2 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., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.
+
+   HP in their infinite stupidity choose not to use standard ELF dynamic
+   linker interfaces.  They also choose not to make their ELF dymamic
+   linker interfaces compatible with the SOM dynamic linker.  The
+   net result is we can not use either of the existing somsolib.c or
+   solib.c.  What a crock.
+
+   Even more disgusting.  This file depends on functions provided only
+   in certain PA64 libraries.  Thus this file is supposed to only be
+   used native.  When will HP ever learn that they need to provide the
+   same functionality in all their libraries!  */
+
+#include <dlfcn.h>
+#include <elf.h>
+#include <elf_hp.h>
+
+#include "defs.h"
+
+#include "frame.h"
+#include "bfd.h"
+#include "libhppa.h"
+#include "gdbcore.h"
+#include "symtab.h"
+#include "breakpoint.h"
+#include "symfile.h"
+#include "objfiles.h"
+#include "inferior.h"
+#include "gdb-stabs.h"
+#include "gdb_stat.h"
+#include "gdbcmd.h"
+#include "assert.h"
+#include "language.h"
+
+#include <fcntl.h>
+
+#ifndef O_BINARY
+#define O_BINARY 0
+#endif
+
+/* Defined in exec.c; used to prevent dangling pointer bug.  */
+extern struct target_ops exec_ops;
+
+static CORE_ADDR
+  bfd_lookup_symbol PARAMS ((bfd *, char *));
+/* This lives in hppa-tdep.c. */
+extern struct unwind_table_entry *find_unwind_entry PARAMS ((CORE_ADDR pc));
+
+/* These ought to be defined in some public interface, but aren't.  They
+   identify dynamic linker events.  */
+#define DLD_CB_LOAD     1
+#define DLD_CB_UNLOAD   0
+
+/* A structure to keep track of all the known shared objects.  */
+struct so_list
+  {
+    bfd *abfd;
+    char *name;
+    struct so_list *next;
+    struct objfile *objfile;
+    CORE_ADDR pa64_solib_desc_addr;
+    struct load_module_desc pa64_solib_desc;
+    struct section_table *sections;
+    struct section_table *sections_end;
+    boolean loaded;
+  };
+
+static struct so_list *so_list_head;
+
+/* This is the cumulative size in bytes of the symbol tables of all
+   shared objects on the so_list_head list.  (When we say size, here
+   we mean of the information before it is brought into memory and
+   potentially expanded by GDB.)  When adding a new shlib, this value
+   is compared against the threshold size, held by auto_solib_add
+   (in megabytes).  If adding symbols for the new shlib would cause
+   the total size to exceed the threshold, then the new shlib's symbols
+   are not loaded.  */
+static LONGEST pa64_solib_total_st_size;
+
+/* When the threshold is reached for any shlib, we refuse to add
+   symbols for subsequent shlibs, even if those shlibs' symbols would
+   be small enough to fit under the threshold.  (Although this may
+   result in one, early large shlib preventing the loading of later,
+   smalller shlibs' symbols, it allows us to issue one informational
+   message.  The alternative, to issue a message for each shlib whose
+   symbols aren't loaded, could be a big annoyance where the threshold
+   is exceeded due to a very large number of shlibs.) */
+static int pa64_solib_st_size_threshold_exceeded;
+
+/* When adding fields, be sure to clear them in _initialize_pa64_solib. */
+typedef struct
+  {
+    CORE_ADDR dld_flags_addr;
+    long long dld_flags;
+    sec_ptr dyninfo_sect;
+    boolean have_read_dld_descriptor;
+    boolean is_valid;
+    CORE_ADDR load_map;
+    CORE_ADDR load_map_addr;
+    struct load_module_desc dld_desc;
+  }
+dld_cache_t;
+
+static dld_cache_t dld_cache;
+
+static void pa64_sharedlibrary_info_command PARAMS ((char *, int));
+
+static void pa64_solib_sharedlibrary_command PARAMS ((char *, int));
+
+static void * pa64_target_read_memory PARAMS ((void *, CORE_ADDR, size_t, int));
+
+static boolean read_dld_descriptor PARAMS ((struct target_ops *));
+
+static boolean read_dynamic_info PARAMS ((asection *, dld_cache_t *));
+
+static void add_to_solist PARAMS ((boolean, char *, struct load_module_desc *,
+				   CORE_ADDR, struct target_ops *));
+
+/* When examining the shared library for debugging information we have to
+   look for HP debug symbols, stabs and dwarf2 debug symbols.  */
+static char *pa64_debug_section_names[] = {
+  ".debug_header", ".debug_gntt", ".debug_lntt", ".debug_slt", ".debug_vt",
+  ".stabs", ".stabstr", ".debug_info", ".debug_abbrev", ".debug_aranges",
+  ".debug_macinfo", ".debug_line", ".debug_loc", ".debug_pubnames",
+  ".debug_str", NULL
+};
+
+/* Return a ballbark figure for the amount of memory GDB will need to
+   allocate to read in the debug symbols from FILENAME.  */
+static LONGEST
+pa64_solib_sizeof_symbol_table (filename)
+     char *filename;
+{
+  bfd *abfd;
+  int i;
+  int desc;
+  char *absolute_name;
+  LONGEST st_size = (LONGEST) 0;
+  asection *sect;
+
+  /* We believe that filename was handed to us by the dynamic linker, and
+     is therefore always an absolute path.  */
+  desc = openp (getenv ("PATH"), 1, filename, O_RDONLY | O_BINARY,
+		0, &absolute_name);
+  if (desc < 0)
+    {
+      perror_with_name (filename);
+    }
+  filename = absolute_name;
+
+  abfd = bfd_fdopenr (filename, gnutarget, desc);
+  if (!abfd)
+    {
+      close (desc);
+      make_cleanup (free, filename);
+      error ("\"%s\": can't open to read symbols: %s.", filename,
+	     bfd_errmsg (bfd_get_error ()));
+    }
+
+  if (!bfd_check_format (abfd, bfd_object))
+    {
+      bfd_close (abfd);
+      make_cleanup (free, filename);
+      error ("\"%s\": can't read symbols: %s.", filename,
+	     bfd_errmsg (bfd_get_error ()));
+    }
+
+  /* Sum the sizes of the various sections that compose debug info. */
+  for (i = 0; pa64_debug_section_names[i] != NULL; i++)
+    {
+      asection *sect;
+
+      sect = bfd_get_section_by_name (abfd, pa64_debug_section_names[i]);
+      if (sect)
+	st_size += (LONGEST)bfd_section_size (abfd, sect);
+    }
+
+  bfd_close (abfd);
+  free (filename);
+
+  /* Unfortunately, just summing the sizes of various debug info
+     sections isn't a very accurate measurement of how much heap
+     space the debugger will need to hold them.  It also doesn't
+     account for space needed by linker (aka "minimal") symbols.
+
+     Anecdotal evidence suggests that just summing the sizes of
+     debug-info-related sections understates the heap space needed
+     to represent it internally by about an order of magnitude.
+
+     Since it's not exactly brain surgery we're doing here, rather
+     than attempt to more accurately measure the size of a shlib's
+     symbol table in GDB's heap, we'll just apply a 10x fudge-
+     factor to the debug info sections' size-sum.  No, this doesn't
+     account for minimal symbols in non-debuggable shlibs.  But it
+     all roughly washes out in the end.  */
+  return st_size * (LONGEST) 10;
+}
+
+/* Add a shared library to the objfile list and load its symbols into
+   GDB's symbol table.  */
+static void
+pa64_solib_add_solib_objfile (so, name, from_tty, text_addr)
+     struct so_list *so;
+     char *name;
+     int from_tty;
+     CORE_ADDR text_addr;
+{
+  bfd *tmp_bfd;
+  asection *sec;
+  obj_private_data_t *obj_private;
+
+  /* We need the BFD so that we can look at its sections.  We open up the
+     file temporarily, then close it when we are done.  */
+  tmp_bfd = bfd_openr (name, gnutarget);
+  if (tmp_bfd == NULL)
+    {
+      perror_with_name (name);
+      return;
+    }
+
+  if (!bfd_check_format (tmp_bfd, bfd_object))
+    {
+      bfd_close (tmp_bfd);
+      error ("\"%s\" is not an object file: %s", name,
+	     bfd_errmsg (bfd_get_error ()));
+    }
+
+
+  /* Undo some braindamage from symfile.c.
+
+     First, symfile.c will subtract the VMA of the first .text section
+     in the shared library that it finds.  Undo that.  */
+  sec = bfd_get_section_by_name (tmp_bfd, ".text");
+  text_addr += bfd_section_vma (tmp_bfd, sec);
+
+  /* Now find the true lowest section in the shared library.  */
+  sec = NULL;
+  bfd_map_over_sections (tmp_bfd, find_lowest_section, (PTR) &sec);
+
+  if (sec)
+    {
+      /* Subtract out the VMA of the lowest section.  */
+      text_addr -= bfd_section_vma (tmp_bfd, sec);
+
+      /* ??? Add back in the filepos of that lowest section. */
+      text_addr += sec->filepos;
+    }
+
+  /* We are done with the temporary bfd.  Get rid of it and make sure
+     nobody else can us it.  */
+  bfd_close (tmp_bfd);
+  tmp_bfd = NULL;
+
+  /* Now let the generic code load up symbols for this library.  */
+  so->objfile = symbol_file_add (name, from_tty, text_addr, 0, 0, 0, 0, 1);
+  so->abfd = so->objfile->obfd;
+
+  /* Mark this as a shared library and save private data.  */
+  so->objfile->flags |= OBJF_SHARED;
+
+  if (so->objfile->obj_private == NULL)
+    {
+      obj_private = (obj_private_data_t *)
+	obstack_alloc (&so->objfile->psymbol_obstack,
+		       sizeof (obj_private_data_t));
+      obj_private->unwind_info = NULL;
+      obj_private->so_info = NULL;
+      so->objfile->obj_private = (PTR) obj_private;
+    }
+
+  obj_private = (obj_private_data_t *) so->objfile->obj_private;
+  obj_private->so_info = so;
+  obj_private->dp = so->pa64_solib_desc.linkage_ptr;
+}
+
+/* Load debugging information for a shared library.  TARGET may be
+   NULL if we are not attaching to a process or reading a core file.  */
+
+static void
+pa64_solib_load_symbols (so, name, from_tty, text_addr, target)
+     struct so_list *so;
+     char *name;
+     int from_tty;
+     CORE_ADDR text_addr;
+     struct target_ops *target;
+{
+  struct section_table *p;
+  asection *sec;
+  int status;
+  char buf[4];
+  CORE_ADDR presumed_data_start;
+
+  if (text_addr == 0)
+    text_addr = so->pa64_solib_desc.text_base;
+
+  pa64_solib_add_solib_objfile (so, name, from_tty, text_addr);
+
+  /* Now we need to build a section table for this library since
+     we might be debugging a core file from a dynamically linked
+     executable in which the libraries were not privately mapped.  */
+  if (build_section_table (so->abfd,
+			   &so->sections,
+			   &so->sections_end))
+    {
+      error ("Unable to build section table for shared library\n.");
+      return;
+    }
+
+  ANOFFSET (so->objfile->section_offsets, SECT_OFF_TEXT)
+    = so->pa64_solib_desc.text_base;
+  ANOFFSET (so->objfile->section_offsets, SECT_OFF_DATA)
+    = so->pa64_solib_desc.data_base;
+
+  /* Relocate all the sections based on where they got loaded.  */
+  for (p = so->sections; p < so->sections_end; p++)
+    {
+      if (p->the_bfd_section->flags & SEC_CODE)
+	{
+	  p->addr += ANOFFSET (so->objfile->section_offsets, SECT_OFF_TEXT);
+	  p->endaddr += ANOFFSET (so->objfile->section_offsets, SECT_OFF_TEXT);
+	}
+      else if (p->the_bfd_section->flags & SEC_DATA)
+	{
+	  p->addr += ANOFFSET (so->objfile->section_offsets, SECT_OFF_DATA);
+	  p->endaddr += ANOFFSET (so->objfile->section_offsets, SECT_OFF_DATA);
+	}
+    }
+
+  /* Now see if we need to map in the text and data for this shared
+     library (for example debugging a core file which does not use
+     private shared libraries.). 
+
+     Carefully peek at the first text address in the library.  If the
+     read succeeds, then the libraries were privately mapped and were
+     included in the core dump file.
+
+     If the peek failed, then the libraries were not privately mapped
+     and are not in the core file, we'll have to read them in ourselves.  */
+  status = target_read_memory (text_addr, buf, 4);
+  if (status != 0)
+    {
+      int old, new;
+      int update_coreops;
+      int update_execops;
+
+      /* We must update the to_sections field in the core_ops structure
+	 here, otherwise we dereference a potential dangling pointer
+	 for each call to target_read/write_memory within this routine.  */
+      update_coreops = core_ops.to_sections == target->to_sections;
+
+      /* Ditto exec_ops (this was a bug).  */
+      update_execops = exec_ops.to_sections == target->to_sections;
+
+      new = so->sections_end - so->sections;
+      /* Add sections from the shared library to the core target.  */
+      if (target->to_sections)
+	{
+	  old = target->to_sections_end - target->to_sections;
+	  target->to_sections = (struct section_table *)
+	    xrealloc ((char *) target->to_sections,
+		      ((sizeof (struct section_table)) * (old + new)));
+	}
+      else
+	{
+	  old = 0;
+	  target->to_sections = (struct section_table *)
+	    xmalloc ((sizeof (struct section_table)) * new);
+	}
+      target->to_sections_end = (target->to_sections + old + new);
+
+      /* Update the to_sections field in the core_ops structure
+	 if needed, ditto exec_ops.  */
+      if (update_coreops)
+	{
+	  core_ops.to_sections = target->to_sections;
+	  core_ops.to_sections_end = target->to_sections_end;
+	}
+
+      if (update_execops)
+	{
+	  exec_ops.to_sections = target->to_sections;
+	  exec_ops.to_sections_end = target->to_sections_end;
+	}
+
+      /* Copy over the old data before it gets clobbered.  */
+      memcpy ((char *) (target->to_sections + old),
+	      so->sections,
+	      ((sizeof (struct section_table)) * new));
+    }
+}
+
+
+/* Add symbols from shared libraries into the symtab list, unless the
+   size threshold (specified by auto_solib_add, in megabytes) would
+   be exceeded.  */
+
+void
+pa64_solib_add (arg_string, from_tty, target)
+     char *arg_string;
+     int from_tty;
+     struct target_ops *target;
+{
+  struct minimal_symbol *msymbol;
+  CORE_ADDR addr;
+  asection *shlib_info;
+  int status;
+  unsigned int dld_flags;
+  char buf[4], *re_err;
+  int threshold_warning_given = 0;
+  int dll_index;
+  struct load_module_desc dll_desc;
+  char *dll_path;
+
+  /* First validate our arguments.  */
+  if ((re_err = re_comp (arg_string ? arg_string : ".")) != NULL)
+    {
+      error ("Invalid regexp: %s", re_err);
+    }
+
+  /* If we're debugging a core file, or have attached to a running
+     process, then pa64_solib_create_inferior_hook will not have been
+     called.
+
+     We need to first determine if we're dealing with a dynamically
+     linked executable.  If not, then return without an error or warning.
+
+     We also need to examine __dld_flags to determine if the shared library
+     list is valid and to determine if the libraries have been privately
+     mapped.  */
+  if (symfile_objfile == NULL)
+    return;
+
+  /* First see if the objfile was dynamically linked.  */
+  shlib_info = bfd_get_section_by_name (symfile_objfile->obfd, ".dynamic");
+  if (!shlib_info)
+    return;
+
+  /* It's got a .dynamic section, make sure it's not empty.  */
+  if (bfd_section_size (symfile_objfile->obfd, shlib_info) == 0)
+    return;
+
+  /* Read in the load map pointer if we have not done so already.  */
+  if (! dld_cache.have_read_dld_descriptor)
+    if (! read_dld_descriptor (target))
+      return;
+
+  /* If the libraries were not mapped private, warn the user.  */
+  if ((dld_cache.dld_flags & DT_HP_DEBUG_PRIVATE) == 0)
+    warning ("The shared libraries were not privately mapped; setting a\nbreakpoint in a shared library will not work until you rerun the program.\n");
+
+  /* For each shaerd library, add it to the shared library list.  */
+  for (dll_index = 1; ; dll_index++)
+    {
+      /* Read in the load module descriptor.  */
+      if (dlgetmodinfo (dll_index, &dll_desc, sizeof (dll_desc),
+			pa64_target_read_memory, 0, dld_cache.load_map)
+	  == 0)
+	return;
+
+      /* Get the name of the shared library.  */
+      dll_path = (char *)dlgetname (&dll_desc, sizeof (dll_desc),
+			    pa64_target_read_memory,
+			    0, dld_cache.load_map);
+
+      if (!dll_path)
+	error ("pa64_solib_add, unable to read shared library path.");
+
+      add_to_solist (from_tty, dll_path, &dll_desc, 0, target);
+    }
+}
+
+
+/* This hook gets called just before the first instruction in the
+   inferior process is executed.
+
+   This is our opportunity to set magic flags in the inferior so
+   that GDB can be notified when a shared library is mapped in and
+   to tell the dynamic linker that a private copy of the library is
+   needed (so GDB can set breakpoints in the library).
+
+   We need to set two flag bits in this routine.
+
+     DT_HP_DEBUG_PRIVATE to indicate that shared libraries should be
+     mapped private.
+
+     DT_HP_DEBUG_CALLBACK to indicate that we want the dynamic linker to
+     call the breakpoint routine for significant events.  */
+
+void
+pa64_solib_create_inferior_hook ()
+{
+  struct minimal_symbol *msymbol;
+  unsigned int dld_flags, status;
+  asection *shlib_info, *interp_sect;
+  char buf[4];
+  struct objfile *objfile;
+  CORE_ADDR anaddr;
+
+  /* First, remove all the solib event breakpoints.  Their addresses
+     may have changed since the last time we ran the program.  */
+  remove_solib_event_breakpoints ();
+
+  if (symfile_objfile == NULL)
+    return;
+
+  /* First see if the objfile was dynamically linked.  */
+  shlib_info = bfd_get_section_by_name (symfile_objfile->obfd, ".dynamic");
+  if (!shlib_info)
+    return;
+
+  /* It's got a .dynamic section, make sure it's not empty.  */
+  if (bfd_section_size (symfile_objfile->obfd, shlib_info) == 0)
+    return;
+
+  /* Slam the pid of the process into __d_pid; failing is only a warning!  */
+  msymbol = lookup_minimal_symbol ("__d_pid", NULL, symfile_objfile);
+  if (msymbol == NULL)
+    {
+      warning ("Unable to find __d_pid symbol in object file.");
+      warning ("Suggest linking with /opt/langtools/lib/end.o.");
+      warning ("GDB will be unable to track explicit library load/unload calls");
+      goto keep_going;
+    }
+
+  anaddr = SYMBOL_VALUE_ADDRESS (msymbol);
+  store_unsigned_integer (buf, 4, inferior_pid);
+  status = target_write_memory (anaddr, buf, 4);
+  if (status != 0)
+    {
+      warning ("Unable to write __d_pid");
+      warning ("Suggest linking with /opt/langtools/lib/end.o.");
+      warning ("GDB will be unable to track explicit library load/unload calls");
+      goto keep_going;
+    }
+
+keep_going:
+
+  /* Read in the .dynamic section.  */
+  if (! read_dynamic_info (shlib_info, &dld_cache))
+    error ("Unable to read the .dynamic section.");
+
+  /* Turn on the flags we care about.  */
+  dld_cache.dld_flags |= DT_HP_DEBUG_PRIVATE;
+  /* ?!? Right now GDB is not recognizing hitting the callback breakpoint
+     as a shared library event.  Fix that and remove the #if0 code.  */
+#if 0
+  dld_cache.dld_flags |= DT_HP_DEBUG_CALLBACK;
+#endif
+  status = target_write_memory (dld_cache.dld_flags_addr,
+				(char *) &dld_cache.dld_flags,
+				sizeof (dld_cache.dld_flags));
+  if (status != 0)
+    error ("Unable to modify dynamic linker flags.");
+
+  /* Now we have to create a shared library breakpoint in the dynamic
+     linker.  This can be somewhat tricky since the symbol is inside
+     the dynamic linker (for which we do not have symbols or a base
+     load address!   Luckily I wrote this code for solib.c years ago.  */
+  interp_sect = bfd_get_section_by_name (exec_bfd, ".interp");
+  if (interp_sect)
+    {
+      unsigned int interp_sect_size;
+      char *buf;
+      CORE_ADDR load_addr;
+      bfd *tmp_bfd;
+      CORE_ADDR sym_addr = 0;
+
+      /* Read the contents of the .interp section into a local buffer;
+	 the contents specify the dynamic linker this program uses.  */
+      interp_sect_size = bfd_section_size (exec_bfd, interp_sect);
+      buf = alloca (interp_sect_size);
+      bfd_get_section_contents (exec_bfd, interp_sect,
+				buf, 0, interp_sect_size);
+
+      /* Now we need to figure out where the dynamic linker was
+	 loaded so that we can load its symbols and place a breakpoint
+	 in the dynamic linker itself.
+
+	 This address is stored on the stack.  However, I've been unable
+	 to find any magic formula to find it for Solaris (appears to
+	 be trivial on GNU/Linux).  Therefore, we have to try an alternate
+	 mechanism to find the dynamic linker's base address.  */
+      tmp_bfd = bfd_openr (buf, gnutarget);
+      if (tmp_bfd == NULL)
+	goto get_out;
+
+      /* Make sure the dynamic linker's really a useful object.  */
+      if (!bfd_check_format (tmp_bfd, bfd_object))
+	{
+	  warning ("Unable to grok dynamic linker %s as an object file", buf);
+	  bfd_close (tmp_bfd);
+	  goto get_out;
+	}
+
+      /* We find the dynamic linker's base address by examining the
+	 current pc (which point at the entry point for the dynamic
+	 linker) and subtracting the offset of the entry point. 
+
+	 Also note the breakpoint is the second instruction in the
+	 routine.  */
+      load_addr = read_pc () - tmp_bfd->start_address;
+      sym_addr = bfd_lookup_symbol (tmp_bfd, "__dld_break");
+      sym_addr = load_addr + sym_addr + 4;
+      
+      /* Create the shared library breakpoint.  */
+      create_solib_event_breakpoint (sym_addr);
+
+      /* We're done with the temporary bfd.  */
+      bfd_close (tmp_bfd);
+    }
+
+get_out:
+  /* Wipe out all knowledge of old shared libraries since their
+     mapping can change from one exec to another!  */
+  while (so_list_head)
+    {
+      struct so_list *temp;
+
+      temp = so_list_head;
+      free (so_list_head);
+      so_list_head = temp->next;
+    }
+  clear_symtab_users ();
+}
+
+/* This operation removes the "hook" between GDB and the dynamic linker,
+   which causes the dld to notify GDB of shared library events.
+
+   After this operation completes, the dld will no longer notify GDB of
+   shared library events.  To resume notifications, GDB must call
+   pa64_solib_create_inferior_hook.
+
+   This operation does not remove any knowledge of shared libraries which
+   GDB may already have been notified of.  */
+
+void
+pa64_solib_remove_inferior_hook (pid)
+     int pid;
+{
+  /* Turn off the DT_HP_DEBUG_CALLBACK bit in the dynamic linker flags.  */
+  dld_cache.dld_flags &= ~DT_HP_DEBUG_CALLBACK;
+  target_write_memory (dld_cache.dld_flags_addr,
+		       (char *)&dld_cache.dld_flags,
+		       sizeof (dld_cache.dld_flags));
+}
+
+/* This function creates a breakpoint on the dynamic linker hook, which
+   is called when e.g., a shl_load or shl_unload call is made.  This
+   breakpoint will only trigger when a shl_load call is made.
+
+   If filename is NULL, then loads of any dll will be caught.  Else,
+   only loads of the file whose pathname is the string contained by
+   filename will be caught.
+
+   Undefined behaviour is guaranteed if this function is called before
+   pa64_solib_create_inferior_hook.  */
+
+void
+pa64_solib_create_catch_load_hook (pid, tempflag, filename, cond_string)
+     int pid;
+     int tempflag;
+     char *filename;
+     char *cond_string;
+{
+  create_solib_load_event_breakpoint ("", tempflag, filename, cond_string);
+}
+
+/* This function creates a breakpoint on the dynamic linker hook, which
+   is called when e.g., a shl_load or shl_unload call is made.  This
+   breakpoint will only trigger when a shl_unload call is made.
+
+   If filename is NULL, then unloads of any dll will be caught.  Else,
+   only unloads of the file whose pathname is the string contained by
+   filename will be caught.
+
+   Undefined behaviour is guaranteed if this function is called before
+   pa64_solib_create_inferior_hook.  */
+
+void
+pa64_solib_create_catch_unload_hook (pid, tempflag, filename, cond_string)
+     int pid;
+     int tempflag;
+     char *filename;
+     char *cond_string;
+{
+  create_solib_unload_event_breakpoint ("", tempflag, filename, cond_string);
+}
+
+/* Return nonzero if the dynamic linker has reproted that a library
+   has been loaded.  */
+
+int
+pa64_solib_have_load_event (pid)
+     int pid;
+{
+  CORE_ADDR event_kind;
+
+  event_kind = read_register (ARG0_REGNUM);
+  return (event_kind == DLD_CB_LOAD);
+}
+
+/* Return nonzero if the dynamic linker has reproted that a library
+   has been unloaded.  */
+int
+pa64_solib_have_unload_event (pid)
+     int pid;
+{
+  CORE_ADDR event_kind;
+
+  event_kind = read_register (ARG0_REGNUM);
+  return (event_kind == DLD_CB_UNLOAD);
+}
+
+/* Return a pointer to a string indicating the pathname of the most
+   recently loaded library.
+
+   The caller is reposible for copying the string before the inferior is
+   restarted.  */
+
+char *
+pa64_solib_loaded_library_pathname (pid)
+     int pid;
+{
+  static char dll_path[MAXPATHLEN];
+  CORE_ADDR  dll_path_addr = read_register (ARG3_REGNUM);
+  read_memory_string (dll_path_addr, dll_path, MAXPATHLEN);
+  return dll_path;
+}
+
+/* Return a pointer to a string indicating the pathname of the most
+   recently unloaded library.
+
+   The caller is reposible for copying the string before the inferior is
+   restarted.  */
+
+char *
+pa64_solib_unloaded_library_pathname (pid)
+     int pid;
+{
+  static char dll_path[MAXPATHLEN];
+  CORE_ADDR dll_path_addr = read_register (ARG3_REGNUM);
+  read_memory_string (dll_path_addr, dll_path, MAXPATHLEN);
+  return dll_path;
+}
+
+/* Return nonzero if PC is an address inside the dynamic linker.  */
+
+int
+pa64_solib_in_dynamic_linker (pid, pc)
+     int pid;
+     CORE_ADDR pc;
+{
+  asection *shlib_info;
+
+  if (symfile_objfile == NULL)
+    return 0;
+
+  if (!dld_cache.have_read_dld_descriptor)
+    if (!read_dld_descriptor (&current_target))
+      return 0;
+
+  return (pc >= dld_cache.dld_desc.text_base
+	  && pc < dld_cache.dld_desc.text_base + dld_cache.dld_desc.text_size);
+}
+
+
+/* Return the GOT value for the shared library in which ADDR belongs.  If
+   ADDR isn't in any known shared library, return zero.  */
+
+CORE_ADDR
+pa64_solib_get_got_by_pc (addr)
+     CORE_ADDR addr;
+{
+  struct so_list *so_list = so_list_head;
+  CORE_ADDR got_value = 0;
+
+  while (so_list)
+    {
+      if (so_list->pa64_solib_desc.text_base <= addr
+	  && ((so_list->pa64_solib_desc.text_base
+	       + so_list->pa64_solib_desc.text_size)
+	      > addr))
+	{
+	  got_value = so_list->pa64_solib_desc.linkage_ptr;
+	  break;
+	}
+      so_list = so_list->next;
+    }
+  return got_value;
+}
+
+/* Return the address of the handle of the shared library in which ADDR
+   belongs.  If ADDR isn't in any known shared library, return zero. 
+
+   This function is used in hppa_fix_call_dummy in hppa-tdep.c.  */
+
+CORE_ADDR
+pa64_solib_get_solib_by_pc (addr)
+     CORE_ADDR addr;
+{
+  struct so_list *so_list = so_list_head;
+  CORE_ADDR retval = 0;
+
+  while (so_list)
+    {
+      if (so_list->pa64_solib_desc.text_base <= addr
+	  && ((so_list->pa64_solib_desc.text_base
+	       + so_list->pa64_solib_desc.text_size)
+	      > addr))
+	{
+	  retval = so_list->pa64_solib_desc_addr;
+	  break;
+	}
+      so_list = so_list->next;
+    }
+  return retval;
+}
+
+/* Dump information about all the currently loaded shared libraries.  */
+
+static void
+pa64_sharedlibrary_info_command (ignore, from_tty)
+     char *ignore;
+     int from_tty;
+{
+  struct so_list *so_list = so_list_head;
+
+  if (exec_bfd == NULL)
+    {
+      printf_unfiltered ("no exec file.\n");
+      return;
+    }
+
+  if (so_list == NULL)
+    {
+      printf_unfiltered ("No shared libraries loaded at this time.\n");
+      return;
+    }
+
+  printf_unfiltered ("Shared Object Libraries\n");
+  printf_unfiltered ("    %-19s%-19s%-19s%-19s\n",
+		     "    tstart", "     tend",
+		     "    dstart", "     dend");
+  while (so_list)
+    {
+      unsigned int flags;
+
+      printf_unfiltered ("%s", so_list->name);
+      if (so_list->objfile == NULL)
+	printf_unfiltered ("  (symbols not loaded)");
+      if (so_list->loaded == 0)
+	printf_unfiltered ("  (shared library unloaded)");
+      printf_unfiltered ("  %-18s",
+	local_hex_string_custom (so_list->pa64_solib_desc.linkage_ptr,
+				 "016l"));
+      printf_unfiltered ("\n");
+      printf_unfiltered ("%-18s",
+	local_hex_string_custom (so_list->pa64_solib_desc.text_base,
+				 "016l"));
+      printf_unfiltered (" %-18s",
+	local_hex_string_custom ((so_list->pa64_solib_desc.text_base,
+				  + so_list->pa64_solib_desc.text_size),
+				 "016l"));
+      printf_unfiltered (" %-18s",
+	local_hex_string_custom (so_list->pa64_solib_desc.data_base,
+				 "016l"));
+      printf_unfiltered (" %-18s\n",
+	local_hex_string_custom ((so_list->pa64_solib_desc.data_base,
+				  + so_list->pa64_solib_desc.data_size),
+				 "016l"));
+      so_list = so_list->next;
+    }
+}
+
+/* Load up one or more shared libraries as directed by the user.  */
+
+static void
+pa64_solib_sharedlibrary_command (args, from_tty)
+     char *args;
+     int from_tty;
+{
+  dont_repeat ();
+  pa64_solib_add (args, from_tty, (struct target_ops *) 0);
+}
+
+/* Return the name of the shared library containing ADDR or NULL if ADDR
+   is not contained in any known shared library.  */
+
+char *
+pa64_solib_address (addr)
+     CORE_ADDR addr;
+{
+  struct so_list *so = so_list_head;
+
+  while (so)
+    {
+      /* Is this address within this shlib's text range?  If so,
+	 return the shlib's name.  */
+      if (addr >= so->pa64_solib_desc.text_base
+	  && addr < (so->pa64_solib_desc.text_base
+		     | so->pa64_solib_desc.text_size))
+	return so->name;
+
+      /* Nope, keep looking... */
+      so = so->next;
+    }
+
+  /* No, we couldn't prove that the address is within a shlib. */
+  return NULL;
+}
+
+/* We are killing the inferior and restarting the program.  */
+
+void
+pa64_solib_restart ()
+{
+  struct so_list *sl = so_list_head;
+
+  /* Before the shlib info vanishes, use it to disable any breakpoints
+     that may still be active in those shlibs.  */
+  disable_breakpoints_in_shlibs (0);
+
+  /* Discard all the shlib descriptors.  */
+  while (sl)
+    {
+      struct so_list *next_sl = sl->next;
+      free (sl);
+      sl = next_sl;
+    }
+  so_list_head = NULL;
+
+  pa64_solib_total_st_size = (LONGEST) 0;
+  pa64_solib_st_size_threshold_exceeded = 0;
+
+  dld_cache.is_valid = 0;
+  dld_cache.have_read_dld_descriptor = 0;
+  dld_cache.dld_flags_addr = 0;
+  dld_cache.load_map = 0;
+  dld_cache.load_map_addr = 0;
+  dld_cache.dld_desc.data_base = 0;
+  dld_cache.dld_flags = 0;
+  dld_cache.dyninfo_sect = 0;
+}
+
+void
+_initialize_pa64_solib ()
+{
+  add_com ("sharedlibrary", class_files, pa64_solib_sharedlibrary_command,
+	   "Load shared object library symbols for files matching REGEXP.");
+  add_info ("sharedlibrary", pa64_sharedlibrary_info_command,
+	    "Status of loaded shared object libraries.");
+  add_show_from_set
+    (add_set_cmd ("auto-solib-add", class_support, var_zinteger,
+		  (char *) &auto_solib_add,
+		  "Set autoloading size threshold (in megabytes) of shared library symbols.\n\
+If nonzero, symbols from all shared object libraries will be loaded\n\
+automatically when the inferior begins execution or when the dynamic linker\n\
+informs gdb that a new library has been loaded, until the symbol table\n\
+of the program and libraries exceeds this threshold.\n\
+Otherwise, symbols must be loaded manually, using `sharedlibrary'.",
+		  &setlist),
+     &showlist);
+
+  /* ??rehrauer: On HP-UX, the kernel parameter MAXDSIZ limits how much
+     data space a process can use.  We ought to be reading MAXDSIZ and
+     setting auto_solib_add to some large fraction of that value.  If
+     not that, we maybe ought to be setting it smaller than the default
+     for MAXDSIZ (that being 64Mb, I believe).  However, [1] this threshold
+     is only crudely approximated rather than actually measured, and [2]
+     50 Mbytes is too small for debugging gdb itself.  Thus, the arbitrary
+     100 figure.
+   */
+  auto_solib_add = 100;		/* Megabytes */
+
+  pa64_solib_restart ();
+}
+
+/* Get some HPUX-specific data from a shared lib.  */
+CORE_ADDR
+so_lib_thread_start_addr (so)
+     struct so_list *so;
+{
+  return so->pa64_solib_desc.tls_start_addr;
+}
+
+/* Read the dynamic linker's internal shared library descriptor.
+
+   This must happen after dld starts running, so we can't do it in
+   read_dynamic_info.  Record the fact that we have loaded the
+   descriptor.  If the library is archive bound, then return zero, else
+   return nonzero.  */
+
+static boolean
+read_dld_descriptor (target)
+     struct target_ops *target;
+{
+  char *dll_path;
+  asection *dyninfo_sect;
+
+  /* If necessary call read_dynamic_info to extract the contents of the
+     .dynamic section from the shared library.  */
+  if (!dld_cache.is_valid) 
+    {
+      if (symfile_objfile == NULL)
+	error ("No object file symbols.");
+
+      dyninfo_sect = bfd_get_section_by_name (symfile_objfile->obfd, 
+					      ".dynamic");
+      if (!dyninfo_sect) 
+	{
+	  return 0;
+	}
+
+      if (!read_dynamic_info (dyninfo_sect, &dld_cache))
+	error ("Unable to read in .dynamic section information.");
+    }
+
+  /* Read the load map pointer.  */
+  if (target_read_memory (dld_cache.load_map_addr,
+			  (char*) &dld_cache.load_map,
+			  sizeof(dld_cache.load_map))
+      != 0)
+    {
+      error ("Error while reading in load map pointer.");
+    }
+
+  /* Read in the dld load module descriptor */
+  if (dlgetmodinfo (-1, 
+		    &dld_cache.dld_desc,
+		    sizeof(dld_cache.dld_desc), 
+		    pa64_target_read_memory, 
+		    0, 
+		    dld_cache.load_map)
+      == 0)
+    {
+      error ("Error trying to get information about dynamic linker.");
+    }
+
+  /* Indicate that we have loaded the dld descriptor.  */
+  dld_cache.have_read_dld_descriptor = 1;
+
+  /* Add dld.sl to the list of known shared libraries so that we can
+     do unwind, etc. 
+
+     ?!? This may not be correct.  Consider of dld.sl contains symbols
+     which are also referenced/defined by the user program or some user
+     shared library.  We need to make absolutely sure that we do not
+     pollute the namespace from GDB's point of view.  */
+  dll_path = dlgetname (&dld_cache.dld_desc, 
+			sizeof(dld_cache.dld_desc), 
+			pa64_target_read_memory, 
+			0, 
+			dld_cache.load_map);
+  add_to_solist(0, dll_path,  &dld_cache.dld_desc, 0, target);
+  
+  return 1;
+}
+
+/* Read the .dynamic section and extract the information of interest,
+   which is stored in dld_cache.  The routine elf_locate_base in solib.c 
+   was used as a model for this.  */
+
+static boolean
+read_dynamic_info (dyninfo_sect, dld_cache_p)
+     asection *dyninfo_sect;
+     dld_cache_t *dld_cache_p;
+{
+  char *buf;
+  char *bufend;
+  CORE_ADDR dyninfo_addr;
+  int dyninfo_sect_size;
+  CORE_ADDR entry_addr;
+
+  /* Read in .dynamic section, silently ignore errors.  */
+  dyninfo_addr = bfd_section_vma (symfile_objfile->obfd, dyninfo_sect);
+  dyninfo_sect_size = bfd_section_size (exec_bfd, dyninfo_sect);
+  buf = alloca (dyninfo_sect_size);
+  if (target_read_memory (dyninfo_addr, buf, dyninfo_sect_size))
+    return 0;
+
+  /* Scan the .dynamic section and record the items of interest. 
+     In particular, DT_HP_DLD_FLAGS */
+  for (bufend = buf + dyninfo_sect_size, entry_addr = dyninfo_addr;
+       buf < bufend;
+       buf += sizeof (Elf64_Dyn), entry_addr += sizeof (Elf64_Dyn))
+    {
+      Elf64_Dyn *x_dynp = (Elf64_Dyn*)buf;
+      Elf64_Sxword dyn_tag;
+      CORE_ADDR	dyn_ptr;
+      char pbuf[TARGET_PTR_BIT / HOST_CHAR_BIT];
+
+      dyn_tag = bfd_h_get_64 (symfile_objfile->obfd, 
+			      (bfd_byte*) &x_dynp->d_tag);
+
+      /* We can't use a switch here because dyn_tag is 64 bits and HP's
+	 lame comiler does not handle 64bit items in switch statements.  */
+      if (dyn_tag == DT_NULL)
+	break;
+      else if (dyn_tag == DT_HP_DLD_FLAGS)
+	{
+	  /* Set dld_flags_addr and dld_flags in *dld_cache_p */
+	  dld_cache_p->dld_flags_addr = entry_addr + offsetof(Elf64_Dyn, d_un);
+	  if (target_read_memory (dld_cache_p->dld_flags_addr,
+	  			  (char*) &dld_cache_p->dld_flags, 
+				  sizeof(dld_cache_p->dld_flags))
+	      != 0)
+	    {
+	      error ("Error while reading in .dynamic section of the program.");
+	    }
+	}
+      else if (dyn_tag == DT_HP_LOAD_MAP)
+	{
+	  /* Dld will place the address of the load map at load_map_addr
+	     after it starts running.  */
+	  if (target_read_memory (entry_addr + offsetof(Elf64_Dyn, 
+							d_un.d_ptr),
+				  (char*) &dld_cache_p->load_map_addr,
+				  sizeof(dld_cache_p->load_map_addr))
+	      != 0)
+	    {
+	      error ("Error while reading in .dynamic section of the program.");
+	    }
+	}
+      else 
+	{
+	  /* tag is not of interest */
+	}
+    }
+
+  /* Record other information and set is_valid to 1. */
+  dld_cache_p->dyninfo_sect = dyninfo_sect;
+
+  /* Verify that we read in required info.  These fields are re-set to zero
+     in pa64_solib_restart.  */
+
+  if (dld_cache_p->dld_flags_addr != 0 && dld_cache_p->load_map_addr != 0) 
+    dld_cache_p->is_valid = 1;
+  else 
+    return 0;
+
+  return 1;
+}
+
+/* Wrapper for target_read_memory to make dlgetmodinfo happy.  */
+
+static void *
+pa64_target_read_memory (buffer, ptr, bufsiz, ident)
+     void *buffer;
+     CORE_ADDR ptr;
+     size_t bufsiz;
+     int ident;
+{
+  if (target_read_memory (ptr, buffer, bufsiz) != 0)
+    return 0;
+  return buffer;
+}
+
+/* Called from handle_dynlink_load_event and pa64_solib_add to add
+   a shared library to so_list_head list and possibly to read in the
+   debug information for the library.  
+
+   If load_module_desc_p is NULL, then the load module descriptor must
+   be read from the inferior process at the address load_module_desc_addr.  */
+
+static void
+add_to_solist (from_tty, dll_path, load_module_desc_p,
+	       load_module_desc_addr, target)
+     boolean from_tty; 
+     char *dll_path; 
+     struct load_module_desc *load_module_desc_p;
+     CORE_ADDR load_module_desc_addr;
+     struct target_ops *target;
+{
+  struct so_list *new_so, *so_list_tail;
+  int pa64_solib_st_size_threshhold_exceeded;
+  LONGEST st_size;
+
+  if (symfile_objfile == NULL)
+    return;
+
+  so_list_tail = so_list_head;
+  /* Find the end of the list of shared objects.  */
+  while (so_list_tail && so_list_tail->next)
+    {
+      if (strcmp (so_list_tail->name, dll_path) == 0)
+	return;
+      so_list_tail = so_list_tail->next;
+    }
+
+  if (so_list_tail && strcmp (so_list_tail->name, dll_path) == 0)
+    return;
+
+  /* Add the shared library to the so_list_head list */
+  new_so = (struct so_list *) xmalloc (sizeof (struct so_list));
+  memset ((char *)new_so, 0, sizeof (struct so_list));
+  if (so_list_head == NULL)
+    {
+      so_list_head = new_so;
+      so_list_tail = new_so;
+    }
+  else
+    {
+      so_list_tail->next = new_so;
+      so_list_tail = new_so;
+    }
+
+  /* Initialize the new_so */
+  if (load_module_desc_p)
+    {
+      new_so->pa64_solib_desc = *load_module_desc_p;
+    }
+  else
+    {
+      if (target_read_memory (load_module_desc_addr, 
+			      (char*) &new_so->pa64_solib_desc,
+			      sizeof(struct load_module_desc))
+	  != 0)
+      {
+	error ("Error while reading in dynamic library %s", dll_path);
+      }
+    }
+  
+  new_so->pa64_solib_desc_addr = load_module_desc_addr;
+  new_so->loaded = 1;
+  new_so->name = obsavestring (dll_path, strlen(dll_path),
+			       &symfile_objfile->symbol_obstack);
+
+  /* If we are not going to load the library, tell the user if we
+     haven't already and return.  */
+
+  st_size = pa64_solib_sizeof_symbol_table (dll_path);
+  pa64_solib_st_size_threshhold_exceeded =
+       !from_tty 
+    && (  (st_size + pa64_solib_total_st_size) 
+	> (auto_solib_add * (LONGEST)1000000));
+  if (pa64_solib_st_size_threshhold_exceeded)
+    {
+      pa64_solib_add_solib_objfile (new_so, dll_path, from_tty, 1);
+      return;
+    } 
+
+  /* Now read in debug info. */
+  pa64_solib_total_st_size += st_size;
+
+  /* This fills in new_so->objfile, among others. */
+  pa64_solib_load_symbols (new_so, 
+			   dll_path,
+			   from_tty, 
+			   0);
+  return;
+}
+
+
+/*
+   LOCAL FUNCTION
+
+   bfd_lookup_symbol -- lookup the value for a specific symbol
+
+   SYNOPSIS
+
+   CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname)
+
+   DESCRIPTION
+
+   An expensive way to lookup the value of a single symbol for
+   bfd's that are only temporary anyway.  This is used by the
+   shared library support to find the address of the debugger
+   interface structures in the shared library.
+
+   Note that 0 is specifically allowed as an error return (no
+   such symbol).
+ */
+
+static CORE_ADDR
+bfd_lookup_symbol (abfd, symname)
+     bfd *abfd;
+     char *symname;
+{
+  unsigned int storage_needed;
+  asymbol *sym;
+  asymbol **symbol_table;
+  unsigned int number_of_symbols;
+  unsigned int i;
+  struct cleanup *back_to;
+  CORE_ADDR symaddr = 0;
+
+  storage_needed = bfd_get_symtab_upper_bound (abfd);
+
+  if (storage_needed > 0)
+    {
+      symbol_table = (asymbol **) xmalloc (storage_needed);
+      back_to = make_cleanup (free, (PTR) symbol_table);
+      number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);
+
+      for (i = 0; i < number_of_symbols; i++)
+	{
+	  sym = *symbol_table++;
+	  if (STREQ (sym->name, symname))
+	    {
+	      /* Bfd symbols are section relative. */
+	      symaddr = sym->value + sym->section->vma;
+	      break;
+	    }
+	}
+      do_cleanups (back_to);
+    }
+  return (symaddr);
+}
+