libdw: set address size, offset size and version on fake CUs

There are three "fake CUs" that are associated with .debug_loc,
.debug_loclist and .debug_addr.  These fake CUs are used for "fake
attributes" to provide values that are stored in these sections
instead of in the .debug_info section. These fake CUs didn't have the
address size, offset size and DWARF version set. This meant that
values that depended on those properties might not be interpreted
correctly. One example was the value associated with a DW_OP_addrx
(which comes from the .debug_addr section).

Add a testcase using varlocs to test that addresses can correctly be
retrieved for gcc/clang, DWARF4/5 and 32/64 bits objects.

https://sourceware.org/bugzilla/show_bug.cgi?id=28220

Signed-off-by: Mark Wielaard <[email protected]>

13 files changed, 149 insertions, 8 deletions

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 768d5c25..b707bbfe 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,8 @@
+2021-09-08  Mark Wielaard  <[email protected]>
+
+	* dwarf_begin_elf.c (valid_p): Identify ELF class and use this to set
+	address_size of the fake CUs. Also set offset_size and DWARF version.
+
 2021-09-06  Dmitry V. Levin  <[email protected]>
 
 	* dwarf_begin_elf.c (valid_p): Remove casts of malloc return values.
diff --git a/libdw/dwarf_begin_elf.c b/libdw/dwarf_begin_elf.c
index 7bde61b3..53b44cd4 100644
--- a/libdw/dwarf_begin_elf.c
+++ b/libdw/dwarf_begin_elf.c
@@ -224,6 +224,23 @@ valid_p (Dwarf *result)
       result = NULL;
     }
 
+  /* We are setting up some "fake" CUs, which need an address size.
+     Check the ELF class to come up with something reasonable.  */
+  int elf_addr_size = 8;
+  if (result != NULL)
+    {
+      GElf_Ehdr ehdr;
+      if (gelf_getehdr (result->elf, &ehdr) == NULL)
+	{
+	  Dwarf_Sig8_Hash_free (&result->sig8_hash);
+	  __libdw_seterrno (DWARF_E_INVALID_ELF);
+	  free (result);
+	  result = NULL;
+	}
+      else if (ehdr.e_ident[EI_CLASS] == ELFCLASS32)
+	elf_addr_size = 4;
+    }
+
   /* For dwarf_location_attr () we need a "fake" CU to indicate
      where the "fake" attribute data comes from.  This is a block
      inside the .debug_loc or .debug_loclists section.  */
@@ -247,8 +264,9 @@ valid_p (Dwarf *result)
 	    = (result->sectiondata[IDX_debug_loc]->d_buf
 	       + result->sectiondata[IDX_debug_loc]->d_size);
 	  result->fake_loc_cu->locs = NULL;
-	  result->fake_loc_cu->address_size = 0;
-	  result->fake_loc_cu->version = 0;
+	  result->fake_loc_cu->address_size = elf_addr_size;
+	  result->fake_loc_cu->offset_size = 4;
+	  result->fake_loc_cu->version = 4;
 	  result->fake_loc_cu->split = NULL;
 	}
     }
@@ -274,8 +292,9 @@ valid_p (Dwarf *result)
 	    = (result->sectiondata[IDX_debug_loclists]->d_buf
 	       + result->sectiondata[IDX_debug_loclists]->d_size);
 	  result->fake_loclists_cu->locs = NULL;
-	  result->fake_loclists_cu->address_size = 0;
-	  result->fake_loclists_cu->version = 0;
+	  result->fake_loclists_cu->address_size = elf_addr_size;
+	  result->fake_loclists_cu->offset_size = 4;
+	  result->fake_loclists_cu->version = 5;
 	  result->fake_loclists_cu->split = NULL;
 	}
     }
@@ -306,8 +325,9 @@ valid_p (Dwarf *result)
 	    = (result->sectiondata[IDX_debug_addr]->d_buf
 	       + result->sectiondata[IDX_debug_addr]->d_size);
 	  result->fake_addr_cu->locs = NULL;
-	  result->fake_addr_cu->address_size = 0;
-	  result->fake_addr_cu->version = 0;
+	  result->fake_addr_cu->address_size = elf_addr_size;
+	  result->fake_addr_cu->offset_size = 4;
+	  result->fake_addr_cu->version = 5;
 	  result->fake_addr_cu->split = NULL;
 	}
     }
diff --git a/tests/ChangeLog b/tests/ChangeLog
index caee93d3..1154686a 100644
--- a/tests/ChangeLog
+++ b/tests/ChangeLog
@@ -1,3 +1,17 @@
+2021-09-08  Mark Wielaard  <[email protected]>
+
+	* run-varlocs-vars.sh: New test.
+	* testfile-vars-clang-dwarf4-32.o.bz2: New test file.
+	* testfile-vars-clang-dwarf4-64.o.bz2: Likewise.
+	* testfile-vars-clang-dwarf5-32.o.bz2: Likewise.
+	* testfile-vars-clang-dwarf5-64.o.bz2: Likewise.
+	* testfile-vars-gcc-dwarf4-32.o.bz2: Likewise.
+	* testfile-vars-gcc-dwarf4-64.o.bz2: Likewise.
+	* testfile-vars-gcc-dwarf5-32.o.bz2: Likewise.
+	* testfile-vars-gcc-dwarf5-64.o.bz2: Likewise.
+	* Makefile.am (EXTRA_DIST): Add new test and test files.
+	(TESTS): Add run-varlocs-vars.sh.
+
 2021-09-09  Mark Wielaard  <[email protected]>
 
 	* debuginfod-subr.sh: set -o functrace.
diff --git a/tests/Makefile.am b/tests/Makefile.am
index c586422e..22942733 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -143,7 +143,7 @@ TESTS = run-arextract.sh run-arsymtest.sh run-ar.sh newfile test-nlist \
 	run-dwfl-report-elf-align.sh run-addr2line-test.sh \
 	run-addr2line-i-test.sh run-addr2line-i-lex-test.sh \
 	run-addr2line-i-demangle-test.sh run-addr2line-alt-debugpath.sh \
-	run-varlocs.sh run-exprlocs.sh run-funcretval.sh \
+	run-varlocs.sh run-exprlocs.sh run-varlocs-vars.sh run-funcretval.sh \
 	run-backtrace-native.sh run-backtrace-data.sh run-backtrace-dwarf.sh \
 	run-backtrace-native-biarch.sh run-backtrace-native-core.sh \
 	run-backtrace-native-core-biarch.sh run-backtrace-core-x86_64.sh \
@@ -399,7 +399,16 @@ EXTRA_DIST = run-arextract.sh run-arsymtest.sh run-ar.sh \
 	     testfileppc32.bz2 testfileppc64.bz2 \
 	     testfiles390.bz2 testfiles390x.bz2 \
 	     testfilearm.bz2 testfileaarch64.bz2 \
-	     run-varlocs.sh run-exprlocs.sh testfile-stridex.bz2 \
+	     run-varlocs.sh run-exprlocs.sh run-varlocs-vars.sh \
+	     testfile-vars-clang-dwarf4-32.o.bz2 \
+	     testfile-vars-clang-dwarf4-64.o.bz2 \
+	     testfile-vars-clang-dwarf5-32.o.bz2 \
+	     testfile-vars-clang-dwarf5-64.o.bz2 \
+	     testfile-vars-gcc-dwarf4-32.o.bz2 \
+	     testfile-vars-gcc-dwarf4-64.o.bz2 \
+	     testfile-vars-gcc-dwarf5-32.o.bz2 \
+	     testfile-vars-gcc-dwarf5-64.o.bz2 \
+	     testfile-stridex.bz2 \
 	     testfile_const_type.c testfile_const_type.bz2 \
 	     testfile_implicit_pointer.c testfile_implicit_pointer.bz2 \
 	     testfile_parameter_ref.c testfile_parameter_ref.bz2 \
diff --git a/tests/run-varlocs-vars.sh b/tests/run-varlocs-vars.sh
new file mode 100755
index 00000000..e7598bf0
--- /dev/null
+++ b/tests/run-varlocs-vars.sh
@@ -0,0 +1,93 @@
+#! /bin/sh
+# Copyright (C) 2013, 2021 Red Hat, Inc.
+# This file is part of elfutils.
+#
+# 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 3 of the License, or
+# (at your option) any later version.
+#
+# elfutils 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/>.
+
+. $srcdir/test-subr.sh
+
+# Testfiles generated with:
+#
+# $ cat foo.c
+# int x = 1;
+# int y = 2;
+#
+# for cc in gcc clang; do
+#   for v in 4 5; do
+#     for w in 32 64; do
+#       out="testfile-vars-$cc-dwarf$v-$w.o"
+#       "$cc" -m"$w" -Wall -Wextra -gdwarf-"$v" -c foo.c -o "$out"
+#     done
+#   done
+# done
+
+testfiles testfile-vars-clang-dwarf4-32.o
+testfiles testfile-vars-clang-dwarf4-64.o
+testfiles testfile-vars-clang-dwarf5-32.o
+testfiles testfile-vars-clang-dwarf5-64.o
+testfiles testfile-vars-gcc-dwarf4-32.o
+testfiles testfile-vars-gcc-dwarf4-64.o
+testfiles testfile-vars-gcc-dwarf5-32.o
+testfiles testfile-vars-gcc-dwarf5-64.o
+
+tempfiles varlocs.out
+testrun ${abs_top_builddir}/tests/varlocs --debug --exprlocs -e testfile-vars-clang-dwarf4-32.o | grep exprloc > varlocs.out
+diff -u varlocs.out - <<EOF
+    location (exprloc) {addr(0x0)}
+    location (exprloc) {addr(0x4)}
+EOF
+
+testrun ${abs_top_builddir}/tests/varlocs --debug --exprlocs -e testfile-vars-clang-dwarf4-64.o | grep exprloc > varlocs.out
+diff -u varlocs.out - <<EOF
+    location (exprloc) {addr(0x0)}
+    location (exprloc) {addr(0x4)}
+EOF
+
+testrun ${abs_top_builddir}/tests/varlocs --debug --exprlocs -e testfile-vars-clang-dwarf5-32.o | grep exprloc > varlocs.out
+diff -u varlocs.out - <<EOF
+    location (exprloc) {addr: 0x0}
+    location (exprloc) {addr: 0x4}
+EOF
+
+testrun ${abs_top_builddir}/tests/varlocs --debug --exprlocs -e testfile-vars-clang-dwarf5-32.o | grep exprloc > varlocs.out
+diff -u varlocs.out - <<EOF
+    location (exprloc) {addr: 0x0}
+    location (exprloc) {addr: 0x4}
+EOF
+
+testrun ${abs_top_builddir}/tests/varlocs --debug --exprlocs -e testfile-vars-gcc-dwarf4-32.o | grep exprloc > varlocs.out
+diff -u varlocs.out - <<EOF
+    location (exprloc) {addr(0x0)}
+    location (exprloc) {addr(0x4)}
+EOF
+
+testrun ${abs_top_builddir}/tests/varlocs --debug --exprlocs -e testfile-vars-gcc-dwarf4-64.o | grep exprloc > varlocs.out
+diff -u varlocs.out - <<EOF
+    location (exprloc) {addr(0x0)}
+    location (exprloc) {addr(0x4)}
+EOF
+
+testrun ${abs_top_builddir}/tests/varlocs --debug --exprlocs -e testfile-vars-gcc-dwarf5-32.o | grep exprloc > varlocs.out
+diff -u varlocs.out - <<EOF
+    location (exprloc) {addr(0x0)}
+    location (exprloc) {addr(0x4)}
+EOF
+
+testrun ${abs_top_builddir}/tests/varlocs --debug --exprlocs -e testfile-vars-gcc-dwarf5-64.o | grep exprloc > varlocs.out
+diff -u varlocs.out - <<EOF
+    location (exprloc) {addr(0x0)}
+    location (exprloc) {addr(0x4)}
+EOF
+
+exit 0
diff --git a/tests/testfile-vars-clang-dwarf4-32.o.bz2 b/tests/testfile-vars-clang-dwarf4-32.o.bz2
new file mode 100644
index 00000000..c1ddf81f
--- /dev/null
+++ b/tests/testfile-vars-clang-dwarf4-32.o.bz2
diff --git a/tests/testfile-vars-clang-dwarf4-64.o.bz2 b/tests/testfile-vars-clang-dwarf4-64.o.bz2
new file mode 100644
index 00000000..df33299f
--- /dev/null
+++ b/tests/testfile-vars-clang-dwarf4-64.o.bz2
diff --git a/tests/testfile-vars-clang-dwarf5-32.o.bz2 b/tests/testfile-vars-clang-dwarf5-32.o.bz2
new file mode 100644
index 00000000..b1d6b6c4
--- /dev/null
+++ b/tests/testfile-vars-clang-dwarf5-32.o.bz2
diff --git a/tests/testfile-vars-clang-dwarf5-64.o.bz2 b/tests/testfile-vars-clang-dwarf5-64.o.bz2
new file mode 100644
index 00000000..adf6c6a5
--- /dev/null
+++ b/tests/testfile-vars-clang-dwarf5-64.o.bz2
diff --git a/tests/testfile-vars-gcc-dwarf4-32.o.bz2 b/tests/testfile-vars-gcc-dwarf4-32.o.bz2
new file mode 100644
index 00000000..da9aac73
--- /dev/null
+++ b/tests/testfile-vars-gcc-dwarf4-32.o.bz2
diff --git a/tests/testfile-vars-gcc-dwarf4-64.o.bz2 b/tests/testfile-vars-gcc-dwarf4-64.o.bz2
new file mode 100644
index 00000000..26421644
--- /dev/null
+++ b/tests/testfile-vars-gcc-dwarf4-64.o.bz2
diff --git a/tests/testfile-vars-gcc-dwarf5-32.o.bz2 b/tests/testfile-vars-gcc-dwarf5-32.o.bz2
new file mode 100644
index 00000000..cb1c7054
--- /dev/null
+++ b/tests/testfile-vars-gcc-dwarf5-32.o.bz2
diff --git a/tests/testfile-vars-gcc-dwarf5-64.o.bz2 b/tests/testfile-vars-gcc-dwarf5-64.o.bz2
new file mode 100644
index 00000000..e286f8f7
--- /dev/null
+++ b/tests/testfile-vars-gcc-dwarf5-64.o.bz2