Fix PR gdb/20505 - Make vDSO detection work with core files
Loading a core dump that was either generated on a system running pristine glibc master, or on a Fedora/RHEL system with LD_DEBUG=unused set in the environment, solib-svr4.c:svr4_current_sos fails to filter out the vDSO, resulting in: (gdb) core-file corefile.core^M [New LWP 2362]^M warning: Could not load shared library symbols for linux-vdso.so.1.^M Do you need "set solib-search-path" or "set sysroot"?^M Core was generated by `build-gdb/gdb/testsuite/outputs/gdb.base/corefile/'.^M ... The problem is that gdbarch_vsyscall_range does not support core inferiors at all. When live debugging, we're finding the vDSO's start address with auxv/AT_SYSINFO_EHDR, and then we find the vDSO's size by look for the corresponding mapping, by parsing /proc/PID/maps. When debugging a core dump, we can also determine the starting address from auxv/AT_SYSINFO_EHDR. However, we obviously can't read the core mappings out of the host's /proc. But we can instead look for a corresponding load segment in the core's bfd. gdb/ChangeLog: 2016-08-22 Pedro Alves <palves@redhat.com> PR gdb/20505 * linux-tdep.c (linux_vsyscall_range_raw): For core inferiors, find the vDSO's start address with AT_SYSINFO_EHDR too, and determine the vDSO's size by finding the PT_LOAD segment that matches AT_SYSINFO_EHDR. gdb/testsuite/ChangeLog: 2016-08-22 Pedro Alves <palves@redhat.com> PR gdb/20505 * gdb.base/vdso-warning.exp: Test core dumps too. Use with_test_prefix. Factor out bits to ... (test_no_vdso): ... this new procedure.
This commit is contained in:
Pedro Alves
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5fbe0d878a
commit
6bb90213cb
@ -1,3 +1,11 @@
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2016-08-22 Pedro Alves <palves@redhat.com>
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PR gdb/20505
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* linux-tdep.c (linux_vsyscall_range_raw): For core inferiors,
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find the vDSO's start address with AT_SYSINFO_EHDR too, and
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determine the vDSO's size by finding the PT_LOAD segment that
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matches AT_SYSINFO_EHDR.
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2016-08-19 Yao Qi <yao.qi@linaro.org>
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* aarch64-tdep.c (aarch64_analyze_prologue): Handle register
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@ -2287,17 +2287,42 @@ linux_vsyscall_range_raw (struct gdbarch *gdbarch, struct mem_range *range)
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long pid;
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char *data;
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/* Can't access /proc if debugging a core file. */
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if (!target_has_execution)
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if (target_auxv_search (¤t_target, AT_SYSINFO_EHDR, &range->start) <= 0)
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return 0;
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/* It doesn't make sense to access the host's /proc when debugging a
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core file. Instead, look for the PT_LOAD segment that matches
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the vDSO. */
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if (!target_has_execution)
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{
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Elf_Internal_Phdr *phdrs;
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long phdrs_size;
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int num_phdrs, i;
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phdrs_size = bfd_get_elf_phdr_upper_bound (core_bfd);
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if (phdrs_size == -1)
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return 0;
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phdrs = (Elf_Internal_Phdr *) alloca (phdrs_size);
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num_phdrs = bfd_get_elf_phdrs (core_bfd, phdrs);
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if (num_phdrs == -1)
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return 0;
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for (i = 0; i < num_phdrs; i++)
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if (phdrs[i].p_type == PT_LOAD
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&& phdrs[i].p_vaddr == range->start)
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{
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range->length = phdrs[i].p_memsz;
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return 1;
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}
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return 0;
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}
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/* We need to know the real target PID to access /proc. */
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if (current_inferior ()->fake_pid_p)
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return 0;
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if (target_auxv_search (¤t_target, AT_SYSINFO_EHDR, &range->start) <= 0)
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return 0;
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pid = current_inferior ()->pid;
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/* Note that reading /proc/PID/task/PID/maps (1) is much faster than
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@ -1,3 +1,10 @@
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2016-08-22 Pedro Alves <palves@redhat.com>
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PR gdb/20505
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* gdb.base/vdso-warning.exp: Test core dumps too. Use
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with_test_prefix. Factor out bits to ...
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(test_no_vdso): ... this new procedure.
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2016-08-19 Carl Love <cel@us.ibm.com>
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* gdb.arch/altivec-regs.exp: Use standard_testfile instead of
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@ -13,42 +13,70 @@
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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# Test that on Linux, we don't warn about not finding the vDSO. E.g.:
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#
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# warning: Could not load shared library symbols for linux-vdso.so.1.
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standard_testfile
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if { [prepare_for_testing "failed to prepare" ${testfile} $srcfile] } {
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return -1
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}
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gdb_breakpoint "main"
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with_test_prefix "setup" {
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gdb_breakpoint "main"
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# At least some versions of Fedora/RHEL glibc have local patches that
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# hide the vDSO. This lines re-exposes it. See PR libc/13097,
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# comment 2. There's no support for passing environment variables in
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# the remote protocol, but that's OK -- if we're testing against a
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# glibc that doesn't list the vDSO without this, the test should still
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# pass.
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gdb_test_no_output "set environment LD_DEBUG=unused"
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# At least some versions of Fedora/RHEL glibc have local patches that
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# hide the vDSO. This lines re-exposes it. See PR libc/13097,
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# comment 2. There's no support for passing environment variables in
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# the remote protocol, but that's OK -- if we're testing against a
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# glibc that doesn't list the vDSO without this, the test should still
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# pass.
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gdb_test_no_output "set environment LD_DEBUG=unused"
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}
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gdb_run_cmd
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proc test_no_vdso {command} {
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global srcfile
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global gdb_prompt
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set test "stop without warning"
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gdb_test_multiple "" $test {
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-re "Could not load shared library symbols .*\r\n$gdb_prompt $" {
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fail $test
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set message "startup"
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gdb_test_multiple "$command" $message {
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-re "Could not load shared library symbols .*\r\n$gdb_prompt $" {
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fail $message
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}
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-re "main \\(\\) at .*$srcfile.*\r\n$gdb_prompt $" {
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pass $message
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}
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}
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-re "\r\nBreakpoint \[0-9\]+, main .*\r\n$gdb_prompt $" {
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pass $test
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# Extra testing in case the warning changes and we miss updating
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# the above.
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set test "no vdso without symbols is listed"
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gdb_test_multiple "info shared" $test {
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-re "No\[^\r\n\]+linux-(vdso|gate).*$gdb_prompt $" {
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fail $test
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}
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-re "$gdb_prompt $" {
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pass $test
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}
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}
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}
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# Extra testing in case the warning changes and we miss updating the
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# above.
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set test "no vdso without symbols is listed"
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gdb_test_multiple "info shared" $test {
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-re "No\[^\r\n\]+linux-(vdso|gate).*$gdb_prompt $" {
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fail $test
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}
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-re "$gdb_prompt $" {
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pass $test
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}
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# First, try a live process.
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with_test_prefix "run" {
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gdb_run_cmd
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test_no_vdso ""
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}
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# Now, dump a core, and reload it.
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with_test_prefix "core" {
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set corefile [standard_output_file $testfile.core]
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set core_supported [gdb_gcore_cmd "$corefile" "save a corefile"]
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if {!$core_supported} {
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return -1
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}
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clean_restart ${testfile}
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test_no_vdso "core-file $corefile"
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}
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