This is the mail archive of the binutils@sourceware.org mailing list for the binutils project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: PATCH: Remember the symbol size if it isn't undefined


Hi H.J.,

I just tried it out building the Xenomai RPM for PowerPC - works fine.
Thanks!

Regards,
Sergei

H. J. Lu wrote:
On Fri, Dec 29, 2006 at 11:01:42PM +1300, Nick Clifton wrote:

Hi H. J.


The problem is we remember the symbol size for undefined symbol and
later we find out its size changes. Do we really care if an undefined
symble changes size?

I can't imagine why.



2006-12-28 H.J. Lu <hongjiu.lu@intel.com>

	* elflink.c (elf_link_add_object_symbols): Remember the symbol
	size only if it is defined.

Approved - but - please could you also add a testcase to check for this particular bug ?




The problem is symbol order sensitive:

    16: 0000000000000000    18 FUNC    GLOBAL DEFAULT  UND par
    17: 000000000000030f    23 FUNC    GLOBAL DEFAULT    6 __wrap_par

With --wrap par, when linker sees par, it will lookup __wrap_par.
At this point, __wrap_par is undefined. When linker sees __wrap_par,
it notices that the size of __wrap_par has changed.

I am checking in this patch now.


H.J. ---- bfd/

2006-12-29 H.J. Lu <hongjiu.lu@intel.com>

	* elflink.c (elf_link_add_object_symbols): Remember the symbol
	size only if it is defined.

ld/testsuite/

2006-12-29 H.J. Lu <hongjiu.lu@intel.com>

	* ld-elf/wrap.exp: New file.
	* ld-elf/wrap1.c: Likewise.
	* ld-elf/wrap1.out: Likewise.
	* ld-elf/wrap1a.c: Likewise.
	* ld-elf/wrap1b.c: Likewise.

--- binutils/bfd/elflink.c.wrap 2006-12-28 17:31:36.000000000 -0800
+++ binutils/bfd/elflink.c 2006-12-29 09:39:28.000000000 -0800
@@ -4058,11 +4058,13 @@ elf_link_add_object_symbols (bfd *abfd, }
}
- /* Remember the symbol size and type. */
- if (isym->st_size != 0
+ /* Remember the symbol size if it isn't undefined. */
+ if ((isym->st_size != 0 && isym->st_shndx != SHN_UNDEF)
&& (definition || h->size == 0))
{
- if (h->size != 0 && h->size != isym->st_size && ! size_change_ok)
+ if (h->size != 0
+ && h->size != isym->st_size
+ && ! size_change_ok)
(*_bfd_error_handler)
(_("Warning: size of symbol `%s' changed"
" from %lu in %B to %lu in %B"),
--- binutils/ld/testsuite/ld-elf/wrap.exp.wrap 2006-12-29 09:39:20.000000000 -0800
+++ binutils/ld/testsuite/ld-elf/wrap.exp 2006-12-29 09:38:00.000000000 -0800
@@ -0,0 +1,54 @@
+# Expect script for wrap ELF tests.
+# Copyright 2006 Free Software Foundation, Inc.
+#
+# This file 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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
+#
+
+# Exclude non-ELF targets.
+
+if ![is_elf_format] {
+ return
+}
+
+# The following tests require running the executable generated by ld.
+if ![isnative] {
+ return
+}
+
+# Check if compiler works
+if { [which $CC] == 0 } {
+ return
+}
+
+set build_tests {
+ {"Build libwrap1a.so"
+ "-shared" "-fPIC"
+ {wrap1a.c} {} "libwrap1a.so"}
+ {"Build libwrap1b.so"
+ "-shared tmpdir/libwrap1a.so" "-fPIC"
+ {wrap1b.c} {} "libwrap1b.so"}
+}
+
+set run_tests {
+ {"Run with libwrap1a.so and libwrap1b.so"
+ "--wrap par tmpdir/libwrap1a.so tmpdir/libwrap1b.so" ""
+ {wrap1.c} "wrap1" "wrap1.out"}
+ {"Run with libwrap1b.so and libwrap1a.so"
+ "--wrap par tmpdir/libwrap1b.so tmpdir/libwrap1a.so" ""
+ {wrap1.c} "wrap1" "wrap1.out"}
+}
+
+run_cc_link_tests $build_tests
+run_ld_link_exec_tests [] $run_tests
--- binutils/ld/testsuite/ld-elf/wrap1.c.wrap 2006-12-29 09:39:20.000000000 -0800
+++ binutils/ld/testsuite/ld-elf/wrap1.c 2006-12-29 09:34:38.000000000 -0800
@@ -0,0 +1,8 @@
+extern void par (void);
+
+int
+main (void)
+{
+ par ();
+ return 0;
+}
--- binutils/ld/testsuite/ld-elf/wrap1.out.wrap 2006-12-29 09:39:20.000000000 -0800
+++ binutils/ld/testsuite/ld-elf/wrap1.out 2006-12-29 09:34:25.000000000 -0800
@@ -0,0 +1,3 @@
+__wrap_par +__real_par +par
--- binutils/ld/testsuite/ld-elf/wrap1a.c.wrap 2006-12-29 09:39:20.000000000 -0800
+++ binutils/ld/testsuite/ld-elf/wrap1a.c 2006-12-29 09:35:13.000000000 -0800
@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+void par (void)
+{
+ printf ("par\n");
+}
--- binutils/ld/testsuite/ld-elf/wrap1b.c.wrap 2006-12-29 09:39:20.000000000 -0800
+++ binutils/ld/testsuite/ld-elf/wrap1b.c 2006-12-29 09:35:02.000000000 -0800
@@ -0,0 +1,16 @@
+#include <stdio.h>
+
+extern void par (void);
+
+void __real_par (void)
+{
+ printf ("__real_par \n");
+ par ();
+}
+
+void
+__wrap_par (void)
+{
+ printf ("__wrap_par \n");
+ __real_par ();
+}




Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]