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binutils-gdb/gdb/solib-sunos.c

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/* Handle SunOS shared libraries for GDB, the GNU Debugger.
Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000,
2001, 2004, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include <sys/types.h>
#include <signal.h>
#include "gdb_string.h"
#include <sys/param.h>
#include <fcntl.h>
/* SunOS shared libs need the nlist structure. */
#include <a.out.h>
#include <link.h>
#include "symtab.h"
#include "bfd.h"
#include "symfile.h"
#include "objfiles.h"
#include "gdbcore.h"
#include "inferior.h"
#include "gdbthread.h"
#include "solist.h"
#include "bcache.h"
#include "regcache.h"
/* The shared library implementation found on BSD a.out systems is
very similar to the SunOS implementation. However, the data
structures defined in <link.h> are named very differently. Make up
for those differences here. */
#ifdef HAVE_STRUCT_SO_MAP_WITH_SOM_MEMBERS
/* FIXME: Temporary until the equivalent defines have been removed
from all nm-*bsd*.h files. */
#ifndef link_dynamic
/* Map `struct link_map' and its members. */
#define link_map so_map
#define lm_addr som_addr
#define lm_name som_path
#define lm_next som_next
/* Map `struct link_dynamic_2' and its members. */
#define link_dynamic_2 section_dispatch_table
#define ld_loaded sdt_loaded
/* Map `struct rtc_symb' and its members. */
#define rtc_symb rt_symbol
#define rtc_sp rt_sp
#define rtc_next rt_next
/* Map `struct ld_debug' and its members. */
#define ld_debug so_debug
#define ldd_in_debugger dd_in_debugger
#define ldd_bp_addr dd_bpt_addr
#define ldd_bp_inst dd_bpt_shadow
#define ldd_cp dd_cc
/* Map `struct link_dynamic' and its members. */
#define link_dynamic _dynamic
#define ld_version d_version
#define ldd d_debug
#define ld_un d_un
#define ld_2 d_sdt
#endif
#endif
/* Link map info to include in an allocated so_list entry */
struct lm_info
{
/* Pointer to copy of link map from inferior. The type is char *
rather than void *, so that we may use byte offsets to find the
various fields without the need for a cast. */
char *lm;
};
/* Symbols which are used to locate the base of the link map structures. */
static char *debug_base_symbols[] =
{
"_DYNAMIC",
"_DYNAMIC__MGC",
NULL
};
static char *main_name_list[] =
{
"main_$main",
NULL
};
/* Macro to extract an address from a solib structure. When GDB is
configured for some 32-bit targets (e.g. Solaris 2.7 sparc), BFD is
configured to handle 64-bit targets, so CORE_ADDR is 64 bits. We
have to extract only the significant bits of addresses to get the
right address when accessing the core file BFD.
Assume that the address is unsigned. */
#define SOLIB_EXTRACT_ADDRESS(MEMBER) \
extract_unsigned_integer (&(MEMBER), sizeof (MEMBER), \
gdbarch_byte_order (target_gdbarch))
/* local data declarations */
static struct link_dynamic dynamic_copy;
static struct link_dynamic_2 ld_2_copy;
static struct ld_debug debug_copy;
static CORE_ADDR debug_addr;
static CORE_ADDR flag_addr;
#ifndef offsetof
#define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER)
#endif
#define fieldsize(TYPE, MEMBER) (sizeof (((TYPE *)0)->MEMBER))
/* link map access functions */
static CORE_ADDR
LM_ADDR (struct so_list *so)
{
enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch);
int lm_addr_offset = offsetof (struct link_map, lm_addr);
int lm_addr_size = fieldsize (struct link_map, lm_addr);
return (CORE_ADDR) extract_signed_integer (so->lm_info->lm + lm_addr_offset,
lm_addr_size, byte_order);
}
static CORE_ADDR
LM_NEXT (struct so_list *so)
{
enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch);
int lm_next_offset = offsetof (struct link_map, lm_next);
int lm_next_size = fieldsize (struct link_map, lm_next);
/* Assume that the address is unsigned. */
return extract_unsigned_integer (so->lm_info->lm + lm_next_offset,
lm_next_size, byte_order);
}
static CORE_ADDR
LM_NAME (struct so_list *so)
{
enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch);
int lm_name_offset = offsetof (struct link_map, lm_name);
int lm_name_size = fieldsize (struct link_map, lm_name);
/* Assume that the address is unsigned. */
return extract_unsigned_integer (so->lm_info->lm + lm_name_offset,
lm_name_size, byte_order);
}
static CORE_ADDR debug_base; /* Base of dynamic linker structures */
/* Local function prototypes */
static int match_main (char *);
/* Allocate the runtime common object file. */
static void
allocate_rt_common_objfile (void)
{
struct objfile *objfile;
struct objfile *last_one;
objfile = (struct objfile *) xmalloc (sizeof (struct objfile));
memset (objfile, 0, sizeof (struct objfile));
objfile->psymbol_cache = bcache_xmalloc ();
objfile->macro_cache = bcache_xmalloc ();
objfile->filename_cache = bcache_xmalloc ();
obstack_init (&objfile->objfile_obstack);
objfile->name = xstrdup ("rt_common");
/* Add this file onto the tail of the linked list of other such files. */
objfile->next = NULL;
if (object_files == NULL)
object_files = objfile;
else
{
for (last_one = object_files;
last_one->next;
last_one = last_one->next);
last_one->next = objfile;
}
rt_common_objfile = objfile;
}
/* Read all dynamically loaded common symbol definitions from the inferior
and put them into the minimal symbol table for the runtime common
objfile. */
static void
solib_add_common_symbols (CORE_ADDR rtc_symp)
{
struct rtc_symb inferior_rtc_symb;
struct nlist inferior_rtc_nlist;
int len;
char *name;
/* Remove any runtime common symbols from previous runs. */
if (rt_common_objfile != NULL && rt_common_objfile->minimal_symbol_count)
{
obstack_free (&rt_common_objfile->objfile_obstack, 0);
obstack_init (&rt_common_objfile->objfile_obstack);
rt_common_objfile->minimal_symbol_count = 0;
rt_common_objfile->msymbols = NULL;
terminate_minimal_symbol_table (rt_common_objfile);
}
init_minimal_symbol_collection ();
make_cleanup_discard_minimal_symbols ();
while (rtc_symp)
{
read_memory (rtc_symp,
(char *) &inferior_rtc_symb,
sizeof (inferior_rtc_symb));
read_memory (SOLIB_EXTRACT_ADDRESS (inferior_rtc_symb.rtc_sp),
(char *) &inferior_rtc_nlist,
sizeof (inferior_rtc_nlist));
if (inferior_rtc_nlist.n_type == N_COMM)
{
/* FIXME: The length of the symbol name is not available, but in the
current implementation the common symbol is allocated immediately
behind the name of the symbol. */
len = inferior_rtc_nlist.n_value - inferior_rtc_nlist.n_un.n_strx;
name = xmalloc (len);
read_memory (SOLIB_EXTRACT_ADDRESS (inferior_rtc_nlist.n_un.n_name),
name, len);
/* Allocate the runtime common objfile if necessary. */
if (rt_common_objfile == NULL)
allocate_rt_common_objfile ();
prim_record_minimal_symbol (name, inferior_rtc_nlist.n_value,
mst_bss, rt_common_objfile);
xfree (name);
}
rtc_symp = SOLIB_EXTRACT_ADDRESS (inferior_rtc_symb.rtc_next);
}
/* Install any minimal symbols that have been collected as the current
minimal symbols for the runtime common objfile. */
install_minimal_symbols (rt_common_objfile);
}
/*
LOCAL FUNCTION
locate_base -- locate the base address of dynamic linker structs
SYNOPSIS
CORE_ADDR locate_base (void)
DESCRIPTION
For both the SunOS and SVR4 shared library implementations, if the
inferior executable has been linked dynamically, there is a single
address somewhere in the inferior's data space which is the key to
locating all of the dynamic linker's runtime structures. This
address is the value of the debug base symbol. The job of this
function is to find and return that address, or to return 0 if there
is no such address (the executable is statically linked for example).
For SunOS, the job is almost trivial, since the dynamic linker and
all of it's structures are statically linked to the executable at
link time. Thus the symbol for the address we are looking for has
already been added to the minimal symbol table for the executable's
objfile at the time the symbol file's symbols were read, and all we
have to do is look it up there. Note that we explicitly do NOT want
to find the copies in the shared library.
The SVR4 version is a bit more complicated because the address
is contained somewhere in the dynamic info section. We have to go
to a lot more work to discover the address of the debug base symbol.
Because of this complexity, we cache the value we find and return that
value on subsequent invocations. Note there is no copy in the
executable symbol tables.
*/
static CORE_ADDR
locate_base (void)
{
struct minimal_symbol *msymbol;
CORE_ADDR address = 0;
char **symbolp;
/* For SunOS, we want to limit the search for the debug base symbol to the
executable being debugged, since there is a duplicate named symbol in the
shared library. We don't want the shared library versions. */
for (symbolp = debug_base_symbols; *symbolp != NULL; symbolp++)
{
msymbol = lookup_minimal_symbol (*symbolp, NULL, symfile_objfile);
if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0))
{
address = SYMBOL_VALUE_ADDRESS (msymbol);
return (address);
}
}
return (0);
}
/*
LOCAL FUNCTION
first_link_map_member -- locate first member in dynamic linker's map
SYNOPSIS
static CORE_ADDR first_link_map_member (void)
DESCRIPTION
Find the first element in the inferior's dynamic link map, and
return its address in the inferior. This function doesn't copy the
link map entry itself into our address space; current_sos actually
does the reading. */
static CORE_ADDR
first_link_map_member (void)
{
CORE_ADDR lm = 0;
read_memory (debug_base, (char *) &dynamic_copy, sizeof (dynamic_copy));
if (dynamic_copy.ld_version >= 2)
{
/* It is a version that we can deal with, so read in the secondary
structure and find the address of the link map list from it. */
read_memory (SOLIB_EXTRACT_ADDRESS (dynamic_copy.ld_un.ld_2),
(char *) &ld_2_copy, sizeof (struct link_dynamic_2));
lm = SOLIB_EXTRACT_ADDRESS (ld_2_copy.ld_loaded);
}
return (lm);
}
static int
open_symbol_file_object (void *from_ttyp)
{
return 1;
}
/* LOCAL FUNCTION
current_sos -- build a list of currently loaded shared objects
SYNOPSIS
struct so_list *current_sos ()
DESCRIPTION
Build a list of `struct so_list' objects describing the shared
objects currently loaded in the inferior. This list does not
include an entry for the main executable file.
Note that we only gather information directly available from the
inferior --- we don't examine any of the shared library files
themselves. The declaration of `struct so_list' says which fields
we provide values for. */
static struct so_list *
sunos_current_sos (void)
{
CORE_ADDR lm;
struct so_list *head = 0;
struct so_list **link_ptr = &head;
int errcode;
char *buffer;
/* Make sure we've looked up the inferior's dynamic linker's base
structure. */
if (! debug_base)
{
debug_base = locate_base ();
/* If we can't find the dynamic linker's base structure, this
must not be a dynamically linked executable. Hmm. */
if (! debug_base)
return 0;
}
/* Walk the inferior's link map list, and build our list of
`struct so_list' nodes. */
lm = first_link_map_member ();
while (lm)
{
struct so_list *new
= (struct so_list *) xmalloc (sizeof (struct so_list));
struct cleanup *old_chain = make_cleanup (xfree, new);
memset (new, 0, sizeof (*new));
new->lm_info = xmalloc (sizeof (struct lm_info));
make_cleanup (xfree, new->lm_info);
new->lm_info->lm = xmalloc (sizeof (struct link_map));
make_cleanup (xfree, new->lm_info->lm);
memset (new->lm_info->lm, 0, sizeof (struct link_map));
read_memory (lm, new->lm_info->lm, sizeof (struct link_map));
lm = LM_NEXT (new);
/* Extract this shared object's name. */
target_read_string (LM_NAME (new), &buffer,
SO_NAME_MAX_PATH_SIZE - 1, &errcode);
if (errcode != 0)
warning (_("Can't read pathname for load map: %s."),
safe_strerror (errcode));
else
{
strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1);
new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
xfree (buffer);
strcpy (new->so_original_name, new->so_name);
}
/* If this entry has no name, or its name matches the name
for the main executable, don't include it in the list. */
if (! new->so_name[0]
|| match_main (new->so_name))
free_so (new);
else
{
new->next = 0;
*link_ptr = new;
link_ptr = &new->next;
}
discard_cleanups (old_chain);
}
return head;
}
/* On some systems, the only way to recognize the link map entry for
the main executable file is by looking at its name. Return
non-zero iff SONAME matches one of the known main executable names. */
static int
match_main (char *soname)
{
char **mainp;
for (mainp = main_name_list; *mainp != NULL; mainp++)
{
if (strcmp (soname, *mainp) == 0)
return (1);
}
return (0);
}
static int
sunos_in_dynsym_resolve_code (CORE_ADDR pc)
{
return 0;
}
/*
LOCAL FUNCTION
disable_break -- remove the "mapping changed" breakpoint
SYNOPSIS
static int disable_break ()
DESCRIPTION
Removes the breakpoint that gets hit when the dynamic linker
completes a mapping change.
*/
static int
disable_break (void)
{
CORE_ADDR breakpoint_addr; /* Address where end bkpt is set */
int in_debugger = 0;
/* Read the debugger structure from the inferior to retrieve the
address of the breakpoint and the original contents of the
breakpoint address. Remove the breakpoint by writing the original
contents back. */
read_memory (debug_addr, (char *) &debug_copy, sizeof (debug_copy));
/* Set `in_debugger' to zero now. */
write_memory (flag_addr, (char *) &in_debugger, sizeof (in_debugger));
breakpoint_addr = SOLIB_EXTRACT_ADDRESS (debug_copy.ldd_bp_addr);
write_memory (breakpoint_addr, (char *) &debug_copy.ldd_bp_inst,
sizeof (debug_copy.ldd_bp_inst));
/* For the SVR4 version, we always know the breakpoint address. For the
SunOS version we don't know it until the above code is executed.
Grumble if we are stopped anywhere besides the breakpoint address. */
if (stop_pc != breakpoint_addr)
{
warning (_("stopped at unknown breakpoint while handling shared libraries"));
}
return 1;
}
/*
LOCAL FUNCTION
enable_break -- arrange for dynamic linker to hit breakpoint
SYNOPSIS
int enable_break (void)
DESCRIPTION
Both the SunOS and the SVR4 dynamic linkers have, as part of their
debugger interface, support for arranging for the inferior to hit
a breakpoint after mapping in the shared libraries. This function
enables that breakpoint.
For SunOS, there is a special flag location (in_debugger) which we
set to 1. When the dynamic linker sees this flag set, it will set
a breakpoint at a location known only to itself, after saving the
original contents of that place and the breakpoint address itself,
in it's own internal structures. When we resume the inferior, it
will eventually take a SIGTRAP when it runs into the breakpoint.
We handle this (in a different place) by restoring the contents of
the breakpointed location (which is only known after it stops),
chasing around to locate the shared libraries that have been
loaded, then resuming.
For SVR4, the debugger interface structure contains a member (r_brk)
which is statically initialized at the time the shared library is
built, to the offset of a function (_r_debug_state) which is guaran-
teed to be called once before mapping in a library, and again when
the mapping is complete. At the time we are examining this member,
it contains only the unrelocated offset of the function, so we have
to do our own relocation. Later, when the dynamic linker actually
runs, it relocates r_brk to be the actual address of _r_debug_state().
The debugger interface structure also contains an enumeration which
is set to either RT_ADD or RT_DELETE prior to changing the mapping,
depending upon whether or not the library is being mapped or unmapped,
and then set to RT_CONSISTENT after the library is mapped/unmapped.
*/
static int
enable_break (void)
{
int success = 0;
int j;
int in_debugger;
/* Get link_dynamic structure */
j = target_read_memory (debug_base, (char *) &dynamic_copy,
sizeof (dynamic_copy));
if (j)
{
/* unreadable */
return (0);
}
/* Calc address of debugger interface structure */
debug_addr = SOLIB_EXTRACT_ADDRESS (dynamic_copy.ldd);
/* Calc address of `in_debugger' member of debugger interface structure */
flag_addr = debug_addr + (CORE_ADDR) ((char *) &debug_copy.ldd_in_debugger -
(char *) &debug_copy);
/* Write a value of 1 to this member. */
in_debugger = 1;
write_memory (flag_addr, (char *) &in_debugger, sizeof (in_debugger));
success = 1;
return (success);
}
/*
LOCAL FUNCTION
special_symbol_handling -- additional shared library symbol handling
SYNOPSIS
void special_symbol_handling ()
DESCRIPTION
Once the symbols from a shared object have been loaded in the usual
way, we are called to do any system specific symbol handling that
is needed.
For SunOS4, this consists of grunging around in the dynamic
linkers structures to find symbol definitions for "common" symbols
and adding them to the minimal symbol table for the runtime common
objfile.
*/
static void
sunos_special_symbol_handling (void)
{
int j;
if (debug_addr == 0)
{
/* Get link_dynamic structure */
j = target_read_memory (debug_base, (char *) &dynamic_copy,
sizeof (dynamic_copy));
if (j)
{
/* unreadable */
return;
}
/* Calc address of debugger interface structure */
/* FIXME, this needs work for cross-debugging of core files
(byteorder, size, alignment, etc). */
debug_addr = SOLIB_EXTRACT_ADDRESS (dynamic_copy.ldd);
}
/* Read the debugger structure from the inferior, just to make sure
we have a current copy. */
j = target_read_memory (debug_addr, (char *) &debug_copy,
sizeof (debug_copy));
if (j)
return; /* unreadable */
/* Get common symbol definitions for the loaded object. */
if (debug_copy.ldd_cp)
{
solib_add_common_symbols (SOLIB_EXTRACT_ADDRESS (debug_copy.ldd_cp));
}
}
/*
GLOBAL FUNCTION
sunos_solib_create_inferior_hook -- shared library startup support
SYNOPSIS
void sunos_solib_create_inferior_hook ()
DESCRIPTION
When gdb starts up the inferior, it nurses it along (through the
shell) until it is ready to execute it's first instruction. At this
point, this function gets called via expansion of the macro
SOLIB_CREATE_INFERIOR_HOOK.
For SunOS executables, this first instruction is typically the
one at "_start", or a similar text label, regardless of whether
the executable is statically or dynamically linked. The runtime
startup code takes care of dynamically linking in any shared
libraries, once gdb allows the inferior to continue.
For SVR4 executables, this first instruction is either the first
instruction in the dynamic linker (for dynamically linked
executables) or the instruction at "start" for statically linked
executables. For dynamically linked executables, the system
first exec's /lib/libc.so.N, which contains the dynamic linker,
and starts it running. The dynamic linker maps in any needed
shared libraries, maps in the actual user executable, and then
jumps to "start" in the user executable.
For both SunOS shared libraries, and SVR4 shared libraries, we
can arrange to cooperate with the dynamic linker to discover the
names of shared libraries that are dynamically linked, and the
base addresses to which they are linked.
This function is responsible for discovering those names and
addresses, and saving sufficient information about them to allow
their symbols to be read at a later time.
FIXME
Between enable_break() and disable_break(), this code does not
properly handle hitting breakpoints which the user might have
set in the startup code or in the dynamic linker itself. Proper
handling will probably have to wait until the implementation is
changed to use the "breakpoint handler function" method.
Also, what if child has exit()ed? Must exit loop somehow.
*/
static void
sunos_solib_create_inferior_hook (int from_tty)
{
struct thread_info *tp;
struct inferior *inf;
if ((debug_base = locate_base ()) == 0)
{
/* Can't find the symbol or the executable is statically linked. */
return;
}
if (!enable_break ())
{
warning (_("shared library handler failed to enable breakpoint"));
return;
}
/* SCO and SunOS need the loop below, other systems should be using the
special shared library breakpoints and the shared library breakpoint
service routine.
Now run the target. It will eventually hit the breakpoint, at
which point all of the libraries will have been mapped in and we
can go groveling around in the dynamic linker structures to find
out what we need to know about them. */
inf = current_inferior ();
tp = inferior_thread ();
clear_proceed_status ();
inf->stop_soon = STOP_QUIETLY;
tp->stop_signal = TARGET_SIGNAL_0;
do
{
target_resume (pid_to_ptid (-1), 0, tp->stop_signal);
wait_for_inferior (0);
}
while (tp->stop_signal != TARGET_SIGNAL_TRAP);
inf->stop_soon = NO_STOP_QUIETLY;
/* We are now either at the "mapping complete" breakpoint (or somewhere
else, a condition we aren't prepared to deal with anyway), so adjust
the PC as necessary after a breakpoint, disable the breakpoint, and
add any shared libraries that were mapped in.
Note that adjust_pc_after_break did not perform any PC adjustment,
as the breakpoint the inferior just hit was not inserted by GDB,
but by the dynamic loader itself, and is therefore not found on
the GDB software break point list. Thus we have to adjust the
PC here. */
if (gdbarch_decr_pc_after_break (target_gdbarch))
{
stop_pc -= gdbarch_decr_pc_after_break (target_gdbarch);
regcache_write_pc (get_current_regcache (), stop_pc);
}
if (!disable_break ())
{
warning (_("shared library handler failed to disable breakpoint"));
}
solib_add ((char *) 0, 0, (struct target_ops *) 0, auto_solib_add);
}
static void
sunos_clear_solib (void)
{
debug_base = 0;
}
static void
sunos_free_so (struct so_list *so)
{
xfree (so->lm_info->lm);
xfree (so->lm_info);
}
static void
sunos_relocate_section_addresses (struct so_list *so,
struct target_section *sec)
{
sec->addr += LM_ADDR (so);
sec->endaddr += LM_ADDR (so);
}
static struct target_so_ops sunos_so_ops;
void
_initialize_sunos_solib (void)
{
sunos_so_ops.relocate_section_addresses = sunos_relocate_section_addresses;
sunos_so_ops.free_so = sunos_free_so;
sunos_so_ops.clear_solib = sunos_clear_solib;
sunos_so_ops.solib_create_inferior_hook = sunos_solib_create_inferior_hook;
sunos_so_ops.special_symbol_handling = sunos_special_symbol_handling;
sunos_so_ops.current_sos = sunos_current_sos;
sunos_so_ops.open_symbol_file_object = open_symbol_file_object;
sunos_so_ops.in_dynsym_resolve_code = sunos_in_dynsym_resolve_code;
sunos_so_ops.bfd_open = solib_bfd_open;
/* FIXME: Don't do this here. *_gdbarch_init() should set so_ops. */
current_target_so_ops = &sunos_so_ops;
}
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