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authorCary Coutant <ccoutant@gmail.com>2016-03-20 19:15:56 -0700
committerCary Coutant <ccoutant@gmail.com>2016-03-20 19:17:14 -0700
commit698400bfb91b3476d98edcb6a4bf5e4abe1c14cc (patch)
tree08b2a8c9742e5fafdca141f3f6561f9c7c25d0b3
parenta3b6c4db68dbcb24c454e6beaaf1002c1ca9e011 (diff)
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Fix problem where gold cannot build .eh_frame_hdr from ld -r output.
When running ld -r on objects that have comdat groups, when gold deduplicates a function in a comdat group, it removes the relocations from the EH information that referred to the dropped copy of the function. When running a final link using the result of the -r link, the missing relocation cause it to fail to recognize the FDE for the dropped function. This patch improves gold's FDE scanning to take into account the possibility that an FDE corresponds to a dropped function, and drops that FDE as well. Gnu ld, on the other hand, leaves the relocations in the ld -r output, but makes them R_NONE with an r_sym field of 0. This was sufficient to let both linkers recognize the FDE properly. With this fix, if you do an ld -r with gold, then do the final link with Gnu ld, the .eh_frame_hdr section will not be generated. To make it work with Gnu ld, we would have to leave the R_NONE relocations in, but I think it's better to drop the relocations entirely. I'd hope that if you're doing a -r link with gold, you'll also do the final link with gold. gold/ PR gold/19002 * ehframe.cc (Eh_frame::read_fde): Check for dropped functions. * testsuite/Makefile.am (eh_test_2): New test. * testsuite/Makefile.in: Regenerate. * testsuite/eh_test_2.sh: New test script. * testsuite/eh_test_a.cc (bar): Make it comdat. * testsuite/eh_test_b.cc (bar): Add a duplicate copy.
-rw-r--r--gold/ChangeLog10
-rw-r--r--gold/ehframe.cc70
-rw-r--r--gold/testsuite/Makefile.am10
-rw-r--r--gold/testsuite/Makefile.in13
-rwxr-xr-xgold/testsuite/eh_test_2.sh37
-rw-r--r--gold/testsuite/eh_test_a.cc7
-rw-r--r--gold/testsuite/eh_test_b.cc10
7 files changed, 145 insertions, 12 deletions
diff --git a/gold/ChangeLog b/gold/ChangeLog
index c903192..854af4b 100644
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,13 @@
+2016-03-20 Cary Coutant <ccoutant@gmail.com>
+
+ PR gold/19002
+ * ehframe.cc (Eh_frame::read_fde): Check for dropped functions.
+ * testsuite/Makefile.am (eh_test_2): New test.
+ * testsuite/Makefile.in: Regenerate.
+ * testsuite/eh_test_2.sh: New test script.
+ * testsuite/eh_test_a.cc (bar): Make it comdat.
+ * testsuite/eh_test_b.cc (bar): Add a duplicate copy.
+
2016-03-18 Vladimir Radosavljevic <vladimir.radosavljevic@imgtec.com>
* mips.cc (Mips_relobj::is_n64_): Remove.
diff --git a/gold/ehframe.cc b/gold/ehframe.cc
index 57eb031..e1a1e74 100644
--- a/gold/ehframe.cc
+++ b/gold/ehframe.cc
@@ -992,13 +992,68 @@ Eh_frame::read_fde(Sized_relobj_file<size, big_endian>* object,
return false;
Cie* cie = pcie->second;
+ int pc_size = 0;
+ switch (cie->fde_encoding() & 7)
+ {
+ case elfcpp::DW_EH_PE_udata2:
+ pc_size = 2;
+ break;
+ case elfcpp::DW_EH_PE_udata4:
+ pc_size = 4;
+ break;
+ case elfcpp::DW_EH_PE_udata8:
+ gold_assert(size == 64);
+ pc_size = 8;
+ break;
+ case elfcpp::DW_EH_PE_absptr:
+ pc_size = size == 32 ? 4 : 8;
+ break;
+ default:
+ // All other cases were rejected in Eh_frame::read_cie.
+ gold_unreachable();
+ }
+
// The FDE should start with a reloc to the start of the code which
// it describes.
if (relocs->advance(pfde - pcontents) > 0)
return false;
-
if (relocs->next_offset() != pfde - pcontents)
- return false;
+ {
+ // In an object produced by a relocatable link, gold may have
+ // discarded a COMDAT group in the previous link, but not the
+ // corresponding FDEs. In that case, gold will have discarded
+ // the relocations, so the FDE will have a non-relocatable zero
+ // (regardless of whether the PC encoding is absolute, pc-relative,
+ // or data-relative) instead of a pointer to the start of the code.
+
+ uint64_t pc_value = 0;
+ switch (pc_size)
+ {
+ case 2:
+ pc_value = elfcpp::Swap<16, big_endian>::readval(pfde);
+ break;
+ case 4:
+ pc_value = elfcpp::Swap<32, big_endian>::readval(pfde);
+ break;
+ case 8:
+ pc_value = elfcpp::Swap_unaligned<64, big_endian>::readval(pfde);
+ break;
+ default:
+ gold_unreachable();
+ }
+
+ if (pc_value == 0)
+ {
+ // This FDE applies to a discarded function. We
+ // can discard this FDE.
+ object->add_merge_mapping(this, shndx, (pfde - 8) - pcontents,
+ pfdeend - (pfde - 8), -1);
+ return true;
+ }
+
+ // Otherwise, reject the FDE.
+ return false;
+ }
unsigned int symndx = relocs->next_symndx();
if (symndx == -1U)
@@ -1031,23 +1086,18 @@ Eh_frame::read_fde(Sized_relobj_file<size, big_endian>* object,
// FDE corresponds to a function that was discarded during optimization
// (too late to discard the corresponding FDE).
uint64_t address_range = 0;
- int pc_size = cie->fde_encoding() & 7;
- if (pc_size == elfcpp::DW_EH_PE_absptr)
- pc_size = size == 32 ? elfcpp::DW_EH_PE_udata4 : elfcpp::DW_EH_PE_udata8;
switch (pc_size)
{
- case elfcpp::DW_EH_PE_udata2:
+ case 2:
address_range = elfcpp::Swap<16, big_endian>::readval(pfde + 2);
break;
- case elfcpp::DW_EH_PE_udata4:
+ case 4:
address_range = elfcpp::Swap<32, big_endian>::readval(pfde + 4);
break;
- case elfcpp::DW_EH_PE_udata8:
- gold_assert(size == 64);
+ case 8:
address_range = elfcpp::Swap_unaligned<64, big_endian>::readval(pfde + 8);
break;
default:
- // All other cases were rejected in Eh_frame::read_cie.
gold_unreachable();
}
diff --git a/gold/testsuite/Makefile.am b/gold/testsuite/Makefile.am
index f5528d1..fbaee16 100644
--- a/gold/testsuite/Makefile.am
+++ b/gold/testsuite/Makefile.am
@@ -388,6 +388,16 @@ eh_test_b.o: eh_test_b.cc
eh_test: eh_test_a.o eh_test_b.o gcctestdir/ld
$(CXXLINK_S) -Bgcctestdir/ eh_test_a.o eh_test_b.o
+check_SCRIPTS += eh_test_2.sh
+check_DATA += eh_test_2.sects
+MOSTLYCLEANFILES += eh_test_2.sects
+eh_test_r.o: eh_test_a.o eh_test_b.o gcctestdir/ld
+ gcctestdir/ld -r -o $@ eh_test_a.o eh_test_b.o
+eh_test_2: eh_test_r.o gcctestdir/ld
+ $(CXXLINK_S) -Bgcctestdir/ -Wl,--eh-frame-hdr eh_test_r.o
+eh_test_2.sects: eh_test_2
+ $(TEST_READELF) -SW $< >$@ 2>/dev/null
+
if HAVE_STATIC
check_PROGRAMS += basic_static_test
basic_static_test: basic_test.o gcctestdir/ld
diff --git a/gold/testsuite/Makefile.in b/gold/testsuite/Makefile.in
index 988d6f7..1246504 100644
--- a/gold/testsuite/Makefile.in
+++ b/gold/testsuite/Makefile.in
@@ -72,7 +72,8 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_string_merge_test.sh \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_sht_rel_addend_test.sh \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ merge_string_literals.sh \
-@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_shared.sh weak_plt.sh
+@GCC_TRUE@@NATIVE_LINKER_TRUE@ eh_test_2.sh two_file_shared.sh \
+@GCC_TRUE@@NATIVE_LINKER_TRUE@ weak_plt.sh
@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_3 = incremental_test.stdout \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ gc_comdat_test.stdout \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ gc_tls_test.stdout \
@@ -95,6 +96,7 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_string_merge_test.stdout \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_sht_rel_addend_test.stdout \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ merge_string_literals.stdout \
+@GCC_TRUE@@NATIVE_LINKER_TRUE@ eh_test_2.sects \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_shared.dbg \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ weak_plt_shared.so
@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_4 = incremental_test \
@@ -119,6 +121,7 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_string_merge_test \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_sht_rel_addend_test \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ merge_string_literals \
+@GCC_TRUE@@NATIVE_LINKER_TRUE@ eh_test_2.sects \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_shared.dbg \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ alt/weak_undef_lib.so \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ libweak_undef_2.a
@@ -4496,6 +4499,8 @@ icf_sht_rel_addend_test.sh.log: icf_sht_rel_addend_test.sh
@p='icf_sht_rel_addend_test.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
merge_string_literals.sh.log: merge_string_literals.sh
@p='merge_string_literals.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
+eh_test_2.sh.log: eh_test_2.sh
+ @p='eh_test_2.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
two_file_shared.sh.log: two_file_shared.sh
@p='two_file_shared.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
weak_plt.sh.log: weak_plt.sh
@@ -5295,6 +5300,12 @@ uninstall-am:
@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(CXXCOMPILE) -O0 -c -o $@ $<
@GCC_TRUE@@NATIVE_LINKER_TRUE@eh_test: eh_test_a.o eh_test_b.o gcctestdir/ld
@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(CXXLINK_S) -Bgcctestdir/ eh_test_a.o eh_test_b.o
+@GCC_TRUE@@NATIVE_LINKER_TRUE@eh_test_r.o: eh_test_a.o eh_test_b.o gcctestdir/ld
+@GCC_TRUE@@NATIVE_LINKER_TRUE@ gcctestdir/ld -r -o $@ eh_test_a.o eh_test_b.o
+@GCC_TRUE@@NATIVE_LINKER_TRUE@eh_test_2: eh_test_r.o gcctestdir/ld
+@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(CXXLINK_S) -Bgcctestdir/ -Wl,--eh-frame-hdr eh_test_r.o
+@GCC_TRUE@@NATIVE_LINKER_TRUE@eh_test_2.sects: eh_test_2
+@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(TEST_READELF) -SW $< >$@ 2>/dev/null
@GCC_TRUE@@HAVE_STATIC_TRUE@@NATIVE_LINKER_TRUE@basic_static_test: basic_test.o gcctestdir/ld
@GCC_TRUE@@HAVE_STATIC_TRUE@@NATIVE_LINKER_TRUE@ $(CXXLINK) -Bgcctestdir/ -static basic_test.o
diff --git a/gold/testsuite/eh_test_2.sh b/gold/testsuite/eh_test_2.sh
new file mode 100755
index 0000000..eb26854
--- /dev/null
+++ b/gold/testsuite/eh_test_2.sh
@@ -0,0 +1,37 @@
+#!/bin/sh
+
+# eh_test_2.sh -- check that .eh_frame_hdr is valid.
+
+# Copyright (C) 2016 Free Software Foundation, Inc.
+# Written by Cary Coutant <ccoutant@gmail.com>.
+
+# This file is part of gold.
+
+# 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, write to the Free Software
+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+sections="eh_test_2.sects"
+
+hdr_section=`fgrep .eh_frame_hdr $sections`
+size_field=`echo $hdr_section | sed -e 's/\[//' | awk '{print $6;}'`
+size=`printf %d "0x$size_field"`
+
+if test "$size" -le 8; then
+ echo ".eh_frame_hdr section is too small:"
+ echo "$hdr_section"
+ exit 1
+fi
+
+exit 0
diff --git a/gold/testsuite/eh_test_a.cc b/gold/testsuite/eh_test_a.cc
index ad4bcc2..e3c8a16 100644
--- a/gold/testsuite/eh_test_a.cc
+++ b/gold/testsuite/eh_test_a.cc
@@ -1,4 +1,9 @@
+template<typename C>
void
-bar()
+bar(C*)
{
}
+
+template
+void
+bar<int>(int*);
diff --git a/gold/testsuite/eh_test_b.cc b/gold/testsuite/eh_test_b.cc
index 50538df..3bf96e9 100644
--- a/gold/testsuite/eh_test_b.cc
+++ b/gold/testsuite/eh_test_b.cc
@@ -6,6 +6,16 @@ foo()
{
}
+template<typename C>
+void
+bar(C*)
+{
+}
+
+template
+void
+bar<int>(int*);
+
int
main()
{