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[PING] [rfc]: Framework for looking up multiply defined global symbols in shared libraries
- From: Markus Deuling <deuling at de dot ibm dot com>
- To: GDB Patches <gdb-patches at sourceware dot org>
- Cc: Ulrich Weigand <uweigand at de dot ibm dot com>
- Date: Thu, 10 May 2007 14:32:10 +0200
- Subject: [PING] [rfc]: Framework for looking up multiply defined global symbols in shared libraries
Hi,
this patch introduces a framework for looking up multiply defined global symbols
from shared libraries. Solib handler like for example solib-svr4.c can now install a callback
to implement a library-specific routine for looking up global symbols.
As an example I implemented a special lookup routine for ELF shared libraries
linked with -Bsymbolic. While the focus is within such a library, the global
symbol lookup shall first search for the symbol within this library and then
go through the main executable if not found.
The patch also includes a testcase for this new feature. The testsuite
showed no regressions.
I would appreciate your comment on this patch. Would this be ok for mainline?
Thanks in advance.
ChangeLog:
* cp-namespace.c (lookup_symbol_file): Add block
to call for lookup_symbol_global.
* Makefile.in (solist_h): Update dependencies.
(solib.o): Likewise.
(symtab.o): Likewise.
* solib.c: New include "symtab.h".
(solib_global_lookup): New function.
* solib-svr4.c (has_SYMBOLIC): New function.
(elf_lookup_lib_symbol): New function.
(_initialize_svr4_solib): Add elf_lookup_lib_symbol
to svr4_so_ops.
* solist.h: New include "symtab.h".
(target_so_ops): New member lookup_lib_global_symbol.
(solib_global_lookup): Declare.
* symtab.c: New include "solist.h".
(lookup_objfile_from_block): New function.
(lookup_global_symbol_from_objfile): New function.
(basic_lookup_symbol_nonlocal): Add block to call
for lookup_symbol_global.
(lookup_symbol_global): Change lookup order. First
call solib_global_lookup then lookup global symbol
in both symtab and psymtab.
* symtab.h (lookup_symbol_global): Add block to
declaration.
(lookup_objfile_from_block): Declare.
(lookup_global_symbol_from_objfile): Declare.
* gdb.base/libmd.c: New file for testcase.
* gdb.base/libmd.h: Likewise.
* gdb.base/solib_symbol.c: Likewise.
* gdb.base/solib_symbol.exp: New testcase for
multiply defined global symbol lookup.
--
Markus Deuling
GNU Toolchain for Linux on Cell BE
deuling@de.ibm.com
diff -urN src/gdb/cp-namespace.c dev/gdb/cp-namespace.c
--- src/gdb/cp-namespace.c 2007-01-09 18:58:50.000000000 +0100
+++ dev/gdb/cp-namespace.c 2007-04-26 07:18:49.000000000 +0200
@@ -491,7 +491,7 @@
}
else
{
- sym = lookup_symbol_global (name, linkage_name, domain, symtab);
+ sym = lookup_symbol_global (name, linkage_name, block, domain, symtab);
}
if (sym != NULL)
diff -urN src/gdb/Makefile.in dev/gdb/Makefile.in
--- src/gdb/Makefile.in 2007-04-26 06:53:55.000000000 +0200
+++ dev/gdb/Makefile.in 2007-04-26 07:18:50.000000000 +0200
@@ -797,7 +797,7 @@
solib_pa64_h = solib-pa64.h
solib_som_h = solib-som.h
solib_svr4_h = solib-svr4.h
-solist_h = solist.h
+solist_h = solist.h $(symtab_h)
source_h = source.h
sparc64_tdep_h = sparc64-tdep.h $(sparc_tdep_h)
sparc_nat_h = sparc-nat.h
@@ -2574,7 +2574,7 @@
$(objfiles_h) $(exceptions_h) $(gdbcore_h) $(command_h) $(target_h) \
$(frame_h) $(gdb_regex_h) $(inferior_h) $(environ_h) $(language_h) \
$(gdbcmd_h) $(completer_h) $(filenames_h) $(exec_h) $(solist_h) \
- $(observer_h) $(readline_h)
+ $(observer_h) $(readline_h) $(symtab_h)
solib-frv.o: solib-frv.c $(defs_h) $(gdb_string_h) $(inferior_h) \
$(gdbcore_h) $(solist_h) $(frv_tdep_h) $(objfiles_h) $(symtab_h) \
$(language_h) $(command_h) $(gdbcmd_h) $(elf_frv_h) $(solib_h)
@@ -2721,7 +2721,8 @@
$(language_h) $(demangle_h) $(inferior_h) $(linespec_h) $(source_h) \
$(filenames_h) $(objc_lang_h) $(ada_lang_h) $(hashtab_h) \
$(gdb_obstack_h) $(block_h) $(dictionary_h) $(gdb_string_h) \
- $(gdb_stat_h) $(cp_abi_h) $(observer_h) $(gdb_assert_h)
+ $(gdb_stat_h) $(cp_abi_h) $(observer_h) $(gdb_assert_h) \
+ $(solist_h)
target.o: target.c $(defs_h) $(gdb_string_h) $(target_h) $(gdbcmd_h) \
$(symtab_h) $(inferior_h) $(bfd_h) $(symfile_h) $(objfiles_h) \
$(gdb_wait_h) $(dcache_h) $(regcache_h) $(gdb_assert_h) $(gdbcore_h) \
diff -urN src/gdb/solib.c dev/gdb/solib.c
--- src/gdb/solib.c 2007-01-09 18:58:58.000000000 +0100
+++ dev/gdb/solib.c 2007-04-26 07:18:50.000000000 +0200
@@ -45,6 +45,7 @@
#include "solist.h"
#include "observer.h"
#include "readline/readline.h"
+#include "symtab.h"
/* Architecture-specific operations. */
@@ -945,6 +946,32 @@
}
+/* Handler for library-specific lookup of global symbol
+ NAME in BLOCK. Detect objfile corresponding to BLOCK
+ and call the library-specific handler if it is installed
+ for the current target. */
+
+struct symbol *
+solib_global_lookup (const struct block *block,
+ const char *name,
+ const char *linkage_name,
+ const domain_enum domain,
+ struct symtab **symtab)
+{
+ struct objfile *objfile;
+
+ objfile = lookup_objfile_from_block (block);
+ if (objfile == NULL)
+ return NULL;
+
+ if (current_target_so_ops->lookup_lib_global_symbol != NULL)
+ return current_target_so_ops->lookup_lib_global_symbol (objfile,
+ name, linkage_name, domain, symtab);
+
+ return NULL;
+}
+
+
extern initialize_file_ftype _initialize_solib; /* -Wmissing-prototypes */
void
diff -urN src/gdb/solib-svr4.c dev/gdb/solib-svr4.c
--- src/gdb/solib-svr4.c 2007-04-16 13:51:29.000000000 +0200
+++ dev/gdb/solib-svr4.c 2007-04-26 07:18:50.000000000 +0200
@@ -378,6 +378,72 @@
*/
+/* Scan OBFD for a SYMBOLIC flag
+ in the .dynamic section. If it is set then
+ OBFD is a dso with a special rule for symbol
+ lookup. The lookup then starts in the dso before
+ searching in the executable. */
+static int
+has_SYMBOLIC (bfd *obfd)
+{
+ CORE_ADDR dyn_ptr = 0;
+ int sect_size, arch_size;
+ gdb_byte *buf, *bufstart, *bufend, *p;
+ asection *sect;
+
+ if (obfd == NULL)
+ return -1;
+ arch_size = bfd_get_arch_size (obfd);
+ if (arch_size == -1)
+ return -1;
+
+ /* Retrieve information about .dynamic section. */
+ sect = bfd_get_section_by_name (obfd, ".dynamic");
+ if (!sect)
+ return -1;
+
+ /* Read the .dynamic section. */
+ sect_size = bfd_section_size (obfd, sect);
+ buf = alloca (sect_size);
+ if (!bfd_get_section_contents (obfd, sect,
+ buf, 0, sect_size))
+ return -1;
+
+ if (arch_size == 32)
+ { /* 32-bit elf */
+ for (bufend = buf + sect_size;
+ buf < bufend;
+ buf += sizeof (Elf32_External_Dyn))
+ {
+ Elf32_External_Dyn *x_dynp = (Elf32_External_Dyn *) buf;
+ long dyn_tag;
+ dyn_tag = extract_unsigned_integer ((gdb_byte *) x_dynp->d_tag, 4);
+ if (dyn_tag == DT_NULL)
+ break;
+ else if (dyn_tag == DT_SYMBOLIC)
+ return 1;
+ }
+ }
+ else
+ { /* 64-bit elf */
+ for (bufend = buf + sect_size;
+ buf < bufend;
+ buf += sizeof (Elf64_External_Dyn))
+ {
+ Elf64_External_Dyn *x_dynp = (Elf64_External_Dyn *) buf;
+ long dyn_tag;
+
+ dyn_tag = extract_unsigned_integer ((gdb_byte *) x_dynp->d_tag, 8);
+ if (dyn_tag == DT_NULL)
+ break;
+ else if (dyn_tag == DT_SYMBOLIC)
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
static CORE_ADDR
elf_locate_base (void)
{
@@ -1558,6 +1624,24 @@
static struct target_so_ops svr4_so_ops;
+/* Lookup global symbol for ELF dso's linked with -Bsymbolic.
+ Those dso's have a different rule for symbol lookup. The lookup
+ begins here in the dso, not in the main executable. */
+
+static struct symbol *
+elf_lookup_lib_symbol (struct objfile *objfile,
+ const char *name,
+ const char *linkage_name,
+ const domain_enum domain, struct symtab **symtab)
+{
+ if (objfile->obfd == NULL
+ || has_SYMBOLIC (objfile->obfd) != 1)
+ return NULL;
+
+ return lookup_global_symbol_from_objfile
+ (objfile, name, linkage_name, domain, symtab);
+}
+
extern initialize_file_ftype _initialize_svr4_solib; /* -Wmissing-prototypes */
void
@@ -1573,6 +1657,7 @@
svr4_so_ops.current_sos = svr4_current_sos;
svr4_so_ops.open_symbol_file_object = open_symbol_file_object;
svr4_so_ops.in_dynsym_resolve_code = svr4_in_dynsym_resolve_code;
+ svr4_so_ops.lookup_lib_global_symbol = elf_lookup_lib_symbol;
/* FIXME: Don't do this here. *_gdbarch_init() should set so_ops. */
current_target_so_ops = &svr4_so_ops;
diff -urN src/gdb/solist.h dev/gdb/solist.h
--- src/gdb/solist.h 2007-01-09 18:58:58.000000000 +0100
+++ dev/gdb/solist.h 2007-04-26 07:18:50.000000000 +0200
@@ -23,6 +23,7 @@
#define SOLIST_H
#define SO_NAME_MAX_PATH_SIZE 512 /* FIXME: Should be dynamic */
+#include "symtab.h"
/* Forward declaration for target specific link map information. This
struct is opaque to all but the target specific file. */
@@ -103,7 +104,14 @@
Convenience function for remote debuggers finding host libs. */
int (*find_and_open_solib) (char *soname,
unsigned o_flags, char **temp_pathname);
-
+
+ /* Hook for looking up global symbols in a library-specific way. */
+ struct symbol * (*lookup_lib_global_symbol) (struct objfile *objfile,
+ const char *name,
+ const char *linkage_name,
+ const domain_enum domain,
+ struct symtab **symtab);
+
};
/* Free the memory associated with a (so_list *). */
@@ -125,4 +133,13 @@
#define TARGET_SO_IN_DYNSYM_RESOLVE_CODE \
(current_target_so_ops->in_dynsym_resolve_code)
+/* Handler for library-specific global symbol lookup
+ in solib.c. */
+struct symbol *
+solib_global_lookup (const struct block *block,
+ const char *name,
+ const char *linkage_name,
+ const domain_enum domain,
+ struct symtab **symtab);
+
#endif
diff -urN src/gdb/symtab.c dev/gdb/symtab.c
--- src/gdb/symtab.c 2007-04-18 13:12:57.000000000 +0200
+++ dev/gdb/symtab.c 2007-04-26 07:18:50.000000000 +0200
@@ -57,6 +57,7 @@
#include "cp-abi.h"
#include "observer.h"
#include "gdb_assert.h"
+#include "solist.h"
/* Prototypes for local functions */
@@ -1265,6 +1266,44 @@
return NULL;
}
+/* Look up objfile to BLOCK. */
+
+struct objfile *
+lookup_objfile_from_block (const struct block *block)
+{
+ struct objfile *obj = NULL;
+ struct blockvector *bv;
+ struct block *b;
+ struct symtab *s;
+ struct partial_symtab *ps;
+
+ if (block == NULL)
+ return NULL;
+
+ /* Go through SYMTABS. */
+ ALL_SYMTABS (obj, s)
+ {
+ bv = BLOCKVECTOR (s);
+ b = BLOCKVECTOR_BLOCK (bv, GLOBAL_BLOCK);
+ if (BLOCK_START (b) <= BLOCK_START (block)
+ && BLOCK_END (b) > BLOCK_START (block))
+ return obj;
+ }
+
+ /* Go through PSYMTABS. */
+ ALL_PSYMTABS (obj, ps)
+ {
+ s = PSYMTAB_TO_SYMTAB (ps);
+ bv = BLOCKVECTOR (s);
+ b = BLOCKVECTOR_BLOCK (bv, GLOBAL_BLOCK);
+ if (BLOCK_START (b) <= BLOCK_START (block)
+ && BLOCK_END (b) > BLOCK_START (block))
+ return obj;
+ }
+
+ return NULL;
+}
+
/* Look up a symbol in a block; if found, locate its symtab, fixup the
symbol, and set block_found appropriately. */
@@ -1306,6 +1345,57 @@
return NULL;
}
+/* Check all global symbols in OBJFILE in symtabs and
+ psymtabs. */
+
+struct symbol *
+lookup_global_symbol_from_objfile (struct objfile *objfile,
+ const char *name,
+ const char *linkage_name,
+ const domain_enum domain,
+ struct symtab **symtab)
+{
+ struct symbol *sym;
+ struct blockvector *bv;
+ const struct block *block;
+ struct symtab *s;
+ struct partial_symtab *ps;
+
+ /* Go through symtabs. */
+ ALL_OBJFILE_SYMTABS (objfile, s)
+ {
+ bv = BLOCKVECTOR (s);
+ block = BLOCKVECTOR_BLOCK (bv, GLOBAL_BLOCK);
+ sym = lookup_block_symbol (block, name, linkage_name, domain);
+ if (sym)
+ {
+ block_found = block;
+ if (symtab != NULL)
+ *symtab = s;
+ return fixup_symbol_section (sym, objfile);
+ }
+ }
+
+ /* Now go through psymtabs. */
+ ALL_OBJFILE_PSYMTABS (objfile, ps)
+ {
+ if (!ps->readin
+ && lookup_partial_symbol (ps, name, linkage_name,
+ 1, domain))
+ {
+ s = PSYMTAB_TO_SYMTAB (ps);
+ bv = BLOCKVECTOR (s);
+ block = BLOCKVECTOR_BLOCK (bv, GLOBAL_BLOCK);
+ sym = lookup_block_symbol (block, name, linkage_name, domain);
+ if (symtab != NULL)
+ *symtab = s;
+ return fixup_symbol_section (sym, objfile);
+ }
+ }
+
+ return NULL;
+}
+
/* Check to see if the symbol is defined in one of the symtabs.
BLOCK_INDEX should be either GLOBAL_BLOCK or STATIC_BLOCK,
depending on whether or not we want to search global symbols or
@@ -1571,7 +1661,7 @@
if (sym != NULL)
return sym;
- return lookup_symbol_global (name, linkage_name, domain, symtab);
+ return lookup_symbol_global (name, linkage_name, block, domain, symtab);
}
/* Lookup a symbol in the static block associated to BLOCK, if there
@@ -1599,18 +1689,28 @@
struct symbol *
lookup_symbol_global (const char *name,
const char *linkage_name,
+ const struct block *block,
const domain_enum domain,
struct symtab **symtab)
{
struct symbol *sym;
+ struct objfile *objfile;
- sym = lookup_symbol_aux_symtabs (GLOBAL_BLOCK, name, linkage_name,
- domain, symtab);
+ /* Call library-specific lookup procedure. */
+ sym = solib_global_lookup (block, name, linkage_name, domain, symtab);
if (sym != NULL)
return sym;
- return lookup_symbol_aux_psymtabs (GLOBAL_BLOCK, name, linkage_name,
- domain, symtab);
+ /* Lookup global symbol in all objfiles in symtab and psymtab. */
+ ALL_OBJFILES (objfile)
+ {
+ sym = lookup_global_symbol_from_objfile (objfile, name, linkage_name,
+ domain, symtab);
+ if (sym != NULL)
+ return sym;
+ }
+
+ return NULL;
}
/* Look, in partial_symtab PST, for symbol whose natural name is NAME.
diff -urN src/gdb/symtab.h dev/gdb/symtab.h
--- src/gdb/symtab.h 2007-03-28 05:42:54.000000000 +0200
+++ dev/gdb/symtab.h 2007-04-26 07:18:50.000000000 +0200
@@ -1050,6 +1050,7 @@
extern struct symbol *lookup_symbol_global (const char *name,
const char *linkage_name,
+ const struct block *block,
const domain_enum domain,
struct symtab **symtab);
@@ -1403,4 +1404,17 @@
Defined in symtab.c, used in hppa-tdep.c. */
extern int deprecated_hp_som_som_object_present;
+/* Lookup objfile to a block. */
+extern struct objfile *
+lookup_objfile_from_block (const struct block *block);
+
+/* Check global symbols in objfile. */
+struct symbol *
+lookup_global_symbol_from_objfile (struct objfile *objfile,
+ const char *name,
+ const char *linkage_name,
+ const domain_enum domain,
+ struct symtab **symtab);
+
+
#endif /* !defined(SYMTAB_H) */
diff -urN src/gdb/testsuite/gdb.base/libmd.c dev/gdb/testsuite/gdb.base/libmd.c
--- src/gdb/testsuite/gdb.base/libmd.c 1970-01-01 01:00:00.000000000 +0100
+++ dev/gdb/testsuite/gdb.base/libmd.c 2007-04-26 07:18:50.000000000 +0200
@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include "libmd.h"
+
+void foo2 ();
+
+void
+foo ()
+{
+ printf ("foo in lib\n");
+ return;
+}
+
+void
+foo2()
+{
+ printf ("foo2 in lib\n");
+ return;
+}
diff -urN src/gdb/testsuite/gdb.base/libmd.h dev/gdb/testsuite/gdb.base/libmd.h
--- src/gdb/testsuite/gdb.base/libmd.h 1970-01-01 01:00:00.000000000 +0100
+++ dev/gdb/testsuite/gdb.base/libmd.h 2007-04-26 07:18:50.000000000 +0200
@@ -0,0 +1 @@
+extern void foo();
diff -urN src/gdb/testsuite/gdb.base/solib_symbol.c dev/gdb/testsuite/gdb.base/solib_symbol.c
--- src/gdb/testsuite/gdb.base/solib_symbol.c 1970-01-01 01:00:00.000000000 +0100
+++ dev/gdb/testsuite/gdb.base/solib_symbol.c 2007-04-26 07:18:50.000000000 +0200
@@ -0,0 +1,27 @@
+#include <stdio.h>
+#include "libmd.h"
+
+extern void foo();
+void foo3();
+void foo2();
+
+int main ()
+{
+ printf ("in main\n");
+ foo ();
+ foo3 ();
+ return 0;
+}
+
+void foo3()
+{
+ printf ("foo3 in main\n");
+ return;
+}
+
+void foo2()
+{
+ printf ("foo2 in main\n");
+ return;
+}
+
diff -urN src/gdb/testsuite/gdb.base/solib_symbol.exp dev/gdb/testsuite/gdb.base/solib_symbol.exp
--- src/gdb/testsuite/gdb.base/solib_symbol.exp 1970-01-01 01:00:00.000000000 +0100
+++ dev/gdb/testsuite/gdb.base/solib_symbol.exp 2007-04-26 07:18:50.000000000 +0200
@@ -0,0 +1,110 @@
+# Copyright 2007 Free Software Foundation, Inc.
+# 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.
+#
+# Contributed by Markus Deuling <deuling@de.ibm.com>.
+#
+
+set prms_id 0
+set bug_id 0
+set timeout 5
+
+if { [istarget "spu-*"] } then {
+ unsupported "Skipping shared libraries testcase."
+ return -1
+}
+
+# Library file.
+set libfile "libmd"
+set srcfile_lib ${libfile}.c
+set binfile_lib ${objdir}/${subdir}/${libfile}.so
+# Binary file.
+set testfile "solib_symbol"
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+
+# Build a solib with -Bsymbolic.
+set compile_flags {debug}
+set compile_flags "$compile_flags additional_flags=-fPIC"
+set compile_flags "$compile_flags additional_flags=-Wl,-Bsymbolic"
+set compile_flags "$compile_flags additional_flags=-shared"
+set sources ${srcdir}/${subdir}/${srcfile_lib}
+if { [gdb_compile $sources ${binfile_lib} executable $compile_flags] != "" } {
+ return -1
+}
+
+# Build binary.
+set compile_flags {debug}
+set compile_flags "$compile_flags additional_flags=-L${objdir}/${subdir}/"
+set compile_flags "$compile_flags additional_flags=-Wl,-rpath=${objdir}/${subdir}/"
+set compile_flags "$compile_flags additional_flags=-lmd"
+set sources ${srcdir}/${subdir}/${srcfile}
+if { [gdb_compile $sources ${binfile} executable $compile_flags] != "" } {
+ return -1
+}
+
+if [get_compiler_info ${binfile}] {
+ return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+if ![runto_main] then {
+ fail "Can't run to main"
+ return 0
+}
+
+# Set a breakpoint in the binary.
+gdb_test "br foo2" \
+ "Breakpoint.*file.*${srcdir}/${subdir}/${srcfile}.*" \
+ "foo2 in main"
+
+# Delete all breakpoints.
+send_gdb "delete breakpoints\n"
+gdb_expect {
+ -re "Delete.*all.*breakpoints.*\(y or n\).*" {
+ send_gdb "y\n"
+ gdb_expect {
+ -re "$gdb_prompt.*" { pass "Delete all breakpoints" }
+ timeout { fail "Delete all breakpoints (timeout)" }
+ }
+ }
+ -re "$gdb_prompt" { fail "Delete all breakpoints" }
+ timeout { fail "Delete all breakpoints (timeout)" }
+}
+
+
+# Break in the library.
+gdb_test "br foo" \
+ "" \
+ "foo in libmd"
+
+gdb_test "continue" \
+ "Continuing.*" \
+ "continue"
+
+# This symbol is now looked up in the ELF library.
+gdb_test "br foo2" \
+ "Breakpoint.*file.*${srcdir}/${subdir}/${srcfile_lib}.*" \
+ "foo2 in mdlib"
+
+
+gdb_exit
+
+return 0
+
+