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Fix assertion failure on aliases of dynamic weak symbols
- From: Richard Sandiford <richard at codesourcery dot com>
- To: binutils at sourceware dot org
- Date: Mon, 16 Jul 2007 18:10:10 +0100
- Subject: Fix assertion failure on aliases of dynamic weak symbols
The attached testcase fails on GNU/Linux targets with:
BFD (GNU Binutils) 2.17.50.20070716 assertion fail .../bfd/elflink.c:2496
A shared library has a weak symbol "foo", and bfd determines that the
strong symbol "data_start" is an alias for "foo" (it has the same section
and value). The shared library is then involved in another link, and the
script for that link defines "data_start" via a PROVIDE statement.
This works in the same way that it would for a non-PROVIDE assignment;
"data_start" is not used as an alias for "foo". However, we handle the
PROVIDE case by setting "data_start"'s type to bfd_link_hash_undefined:
/* If this symbol is being provided by the linker script, and it is
currently defined by a dynamic object, but not by a regular
object, then mark it as undefined so that the generic linker will
force the correct value. */
if (provide
&& h->def_dynamic
&& !h->def_regular)
h->root.type = bfd_link_hash_undefined;
[...]
h->def_regular = 1;
whereas _bfd_elf_fix_symbol_flags expects the type to be
bfd_link_hash_defined or bfd_link_hash_defweak.
The testcase is still being handled correctly, and it doesn't seem
appropriate to weaken the assert by checking for the non-obvious
bfd_link_hash_undefined, so I simply moved the assert into the
!def_regular case (i.e. the one where we continue to use the alias).
I've restricted the test to GNU/Linux targets because not all ELF
targets support -shared.
Tested on x86_64-linux-gnu, i686-pc-linux-gnu, arm-eabi, cris-elf,
mips-linux-gnu, mips64-linux-gnu, mipsisa64-elf, powerpc-linux-gnu,
powerpc64-linux-gnu and ia64-linux-gnu. OK to install?
Richard
bfd/
* elflink.c (_bfd_elf_fix_symbol_flags): Only assert the type
of weakdef->root.type if weakdef has no regular definition.
ld/testsuite/
* ld-elf/weak-dyn-1a.s, ld-elf/weak-dyn-1b.s, ld-elf/weak-dyn-1.ld,
* ld-elf/weak-dyn-1.rd: New test.
* ld-elf/elf.exp: Run it.
Index: bfd/elflink.c
===================================================================
RCS file: /cvs/src/src/bfd/elflink.c,v
retrieving revision 1.269
diff -u -p -r1.269 elflink.c
--- bfd/elflink.c 10 Jul 2007 02:40:31 -0000 1.269
+++ bfd/elflink.c 16 Jul 2007 17:09:19 -0000
@@ -2492,8 +2492,6 @@ _bfd_elf_fix_symbol_flags (struct elf_li
BFD_ASSERT (h->root.type == bfd_link_hash_defined
|| h->root.type == bfd_link_hash_defweak);
- BFD_ASSERT (weakdef->root.type == bfd_link_hash_defined
- || weakdef->root.type == bfd_link_hash_defweak);
BFD_ASSERT (weakdef->def_dynamic);
/* If the real definition is defined by a regular object file,
@@ -2502,8 +2500,11 @@ _bfd_elf_fix_symbol_flags (struct elf_li
if (weakdef->def_regular)
h->u.weakdef = NULL;
else
- (*bed->elf_backend_copy_indirect_symbol) (eif->info, weakdef,
- h);
+ {
+ BFD_ASSERT (weakdef->root.type == bfd_link_hash_defined
+ || weakdef->root.type == bfd_link_hash_defweak);
+ (*bed->elf_backend_copy_indirect_symbol) (eif->info, weakdef, h);
+ }
}
return TRUE;
Index: ld/testsuite/ld-elf/weak-dyn-1a.s
===================================================================
RCS file: ld/testsuite/ld-elf/weak-dyn-1a.s
diff -N ld/testsuite/ld-elf/weak-dyn-1a.s
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ ld/testsuite/ld-elf/weak-dyn-1a.s 16 Jul 2007 17:09:19 -0000
@@ -0,0 +1,7 @@
+ .globl foo
+ .weak foo
+ .type foo,%object
+ .size foo,1
+ .data
+foo:
+ .dc.a data_begin
Index: ld/testsuite/ld-elf/weak-dyn-1b.s
===================================================================
RCS file: ld/testsuite/ld-elf/weak-dyn-1b.s
diff -N ld/testsuite/ld-elf/weak-dyn-1b.s
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ ld/testsuite/ld-elf/weak-dyn-1b.s 16 Jul 2007 17:09:19 -0000
@@ -0,0 +1,3 @@
+ .data
+ .dc.a foo
+ .dc.a data_begin
Index: ld/testsuite/ld-elf/weak-dyn-1.ld
===================================================================
RCS file: ld/testsuite/ld-elf/weak-dyn-1.ld
diff -N ld/testsuite/ld-elf/weak-dyn-1.ld
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ ld/testsuite/ld-elf/weak-dyn-1.ld 16 Jul 2007 17:09:19 -0000
@@ -0,0 +1,8 @@
+SECTIONS
+{
+ . = 0x800000;
+ .data : {
+ PROVIDE (data_begin = .);
+ *(.data)
+ }
+}
Index: ld/testsuite/ld-elf/weak-dyn-1.rd
===================================================================
RCS file: ld/testsuite/ld-elf/weak-dyn-1.rd
diff -N ld/testsuite/ld-elf/weak-dyn-1.rd
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ ld/testsuite/ld-elf/weak-dyn-1.rd 16 Jul 2007 17:09:19 -0000
@@ -0,0 +1,3 @@
+#...
+0+800000 .* foo.*
+#pass
Index: ld/testsuite/ld-elf/elf.exp
===================================================================
RCS file: /cvs/src/src/ld/testsuite/ld-elf/elf.exp,v
retrieving revision 1.10
diff -u -p -r1.10 elf.exp
--- ld/testsuite/ld-elf/elf.exp 6 Jul 2007 14:09:43 -0000 1.10
+++ ld/testsuite/ld-elf/elf.exp 16 Jul 2007 17:09:19 -0000
@@ -36,6 +36,19 @@ foreach t $test_list {
run_dump_test [file rootname $t]
}
+if { [istarget *-*-linux*] } {
+ run_ld_link_tests {
+ {"Weak symbols in dynamic objects 1 (support)"
+ "-shared -Tweak-dyn-1.ld" "" {weak-dyn-1a.s}
+ {}
+ "libweakdyn1a.so"}
+ {"Weak symbols in dynamic objects 1 (main test)"
+ "-shared tmpdir/libweakdyn1a.so -Tweak-dyn-1.ld" "" {weak-dyn-1b.s}
+ {{readelf {--relocs --wide} weak-dyn-1.rd}}
+ "libweakdyn1b.so"}
+ }
+}
+
# The following tests require running the executable generated by ld.
if ![isnative] {
return