Fix stepping in rtld without debug symbol
Commit Message
Commit be6276e0aed "Allow debugging of runtime loader / dynamic linker"
introduced a small regression when stepping into the runtime loader /
dynamic linker from function we do not have debug information for. This
is reported in PR/29747.
This can be shown by the following example (given by Simon Marchi in
buzilla bug report):
$ cat test.c
#include <stdio.h>
int main()
{
printf("Hi\n");
return 0;
}
$ gcc test.c -O0 -o test
$ ./gdb -q -nx --data-directory=data-directory test -ex start -ex s
Reading symbols from test...
(No debugging symbols found in test)
Temporary breakpoint 1 at 0x1151
Starting program: .../binutils-gdb/gdb/test
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Temporary breakpoint 1, 0x0000555555555151 in main ()
Single stepping until exit from function main,
which has no line number information.
/home/smarchi/src/binutils-gdb/gdb/infrun.c:6960:64: runtime error: member call on null pointer of type 'struct symbol'
The crash happens here:
#0 __sanitizer::Die () at ../../../../src/libsanitizer/sanitizer_common/sanitizer_termination.cpp:50
#1 0x00007ffff5dd7128 in __ubsan::__ubsan_handle_type_mismatch_v1_abort (Data=<optimized out>, Pointer=<optimized out>) at ../../../../src/libsanitizer/ubsan/ubsan_handlers.cpp:148
#2 0x000055556183e1a7 in process_event_stop_test (ecs=0x7fffffffccd0) at .../binutils-gdb/gdb/infrun.c:6960
#3 0x0000555561838ea4 in handle_signal_stop (ecs=0x7fffffffccd0) at .../binutils-gdb/gdb/infrun.c:6615
#4 0x000055556182f77b in handle_inferior_event (ecs=0x7fffffffccd0) at .../binutils-gdb/gdb/infrun.c:5866
When evaluating:
6956 if (execution_direction != EXEC_REVERSE
6957 && ecs->event_thread->control.step_over_calls == STEP_OVER_UNDEBUGGABLE
6958 && in_solib_dynsym_resolve_code (ecs->event_thread->stop_pc ())
6959 && !in_solib_dynsym_resolve_code (
6961 ecs->event_thread->control.step_start_function->value_block ()
6962 ->entry_pc ()))
we dereference, ecs->event_thread->control.step_start_function which is
nullptr.
This patch changes this condition so it evaluates to true if
ecs->event_thread->control.step_start_function is nullptr since this
matches the behaviour before be6276e0aed.
Tested on ubuntu-22.04 x86_64.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29747
---
gdb/infrun.c | 7 +++--
gdb/testsuite/gdb.base/rtld-step-nodebugsym.c | 25 +++++++++++++++
.../gdb.base/rtld-step-nodebugsym.exp | 31 +++++++++++++++++++
3 files changed, 60 insertions(+), 3 deletions(-)
create mode 100644 gdb/testsuite/gdb.base/rtld-step-nodebugsym.c
create mode 100644 gdb/testsuite/gdb.base/rtld-step-nodebugsym.exp
base-commit: b0119424d19afcf80997ad5f3128d7ec68e1fafa
Comments
On 04/11/2022 19:26, Lancelot SIX via Gdb-patches wrote:
> Commit be6276e0aed "Allow debugging of runtime loader / dynamic linker"
> introduced a small regression when stepping into the runtime loader /
> dynamic linker from function we do not have debug information for. This
> is reported in PR/29747.
>
> This can be shown by the following example (given by Simon Marchi in
> buzilla bug report):
>
> $ cat test.c
> #include <stdio.h>
>
> int main()
> {
> printf("Hi\n");
> return 0;
> }
> $ gcc test.c -O0 -o test
> $ ./gdb -q -nx --data-directory=data-directory test -ex start -ex s
> Reading symbols from test...
> (No debugging symbols found in test)
> Temporary breakpoint 1 at 0x1151
> Starting program: .../binutils-gdb/gdb/test
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
>
> Temporary breakpoint 1, 0x0000555555555151 in main ()
> Single stepping until exit from function main,
> which has no line number information.
> /home/smarchi/src/binutils-gdb/gdb/infrun.c:6960:64: runtime error: member call on null pointer of type 'struct symbol'
>
> The crash happens here:
>
> #0 __sanitizer::Die () at ../../../../src/libsanitizer/sanitizer_common/sanitizer_termination.cpp:50
> #1 0x00007ffff5dd7128 in __ubsan::__ubsan_handle_type_mismatch_v1_abort (Data=<optimized out>, Pointer=<optimized out>) at ../../../../src/libsanitizer/ubsan/ubsan_handlers.cpp:148
> #2 0x000055556183e1a7 in process_event_stop_test (ecs=0x7fffffffccd0) at .../binutils-gdb/gdb/infrun.c:6960
> #3 0x0000555561838ea4 in handle_signal_stop (ecs=0x7fffffffccd0) at .../binutils-gdb/gdb/infrun.c:6615
> #4 0x000055556182f77b in handle_inferior_event (ecs=0x7fffffffccd0) at .../binutils-gdb/gdb/infrun.c:5866
>
> When evaluating:
>
> 6956 if (execution_direction != EXEC_REVERSE
> 6957 && ecs->event_thread->control.step_over_calls == STEP_OVER_UNDEBUGGABLE
> 6958 && in_solib_dynsym_resolve_code (ecs->event_thread->stop_pc ())
> 6959 && !in_solib_dynsym_resolve_code (
> 6961 ecs->event_thread->control.step_start_function->value_block ()
> 6962 ->entry_pc ()))
>
> we dereference, ecs->event_thread->control.step_start_function which is
> nullptr.
>
> This patch changes this condition so it evaluates to true if
> ecs->event_thread->control.step_start_function is nullptr since this
> matches the behaviour before be6276e0aed.
>
> Tested on ubuntu-22.04 x86_64.
>
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29747
Patch looks alright, I just have one nit inlined.
> ---
> gdb/infrun.c | 7 +++--
> gdb/testsuite/gdb.base/rtld-step-nodebugsym.c | 25 +++++++++++++++
> .../gdb.base/rtld-step-nodebugsym.exp | 31 +++++++++++++++++++
> 3 files changed, 60 insertions(+), 3 deletions(-)
> create mode 100644 gdb/testsuite/gdb.base/rtld-step-nodebugsym.c
> create mode 100644 gdb/testsuite/gdb.base/rtld-step-nodebugsym.exp
>
> diff --git a/gdb/infrun.c b/gdb/infrun.c
> index 5ff0dc44d03..6da46b75ac7 100644
> --- a/gdb/infrun.c
> +++ b/gdb/infrun.c
> @@ -6956,9 +6956,10 @@ process_event_stop_test (struct execution_control_state *ecs)
> if (execution_direction != EXEC_REVERSE
> && ecs->event_thread->control.step_over_calls == STEP_OVER_UNDEBUGGABLE
> && in_solib_dynsym_resolve_code (ecs->event_thread->stop_pc ())
> - && !in_solib_dynsym_resolve_code (
> - ecs->event_thread->control.step_start_function->value_block ()
> - ->entry_pc ()))
> + && (ecs->event_thread->control.step_start_function == nullptr
> + || !in_solib_dynsym_resolve_code (
> + ecs->event_thread->control.step_start_function->value_block ()
> + ->entry_pc ())))
> {
> CORE_ADDR pc_after_resolver =
> gdbarch_skip_solib_resolver (gdbarch, ecs->event_thread->stop_pc ());
> diff --git a/gdb/testsuite/gdb.base/rtld-step-nodebugsym.c b/gdb/testsuite/gdb.base/rtld-step-nodebugsym.c
> new file mode 100644
> index 00000000000..4ad96db1445
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/rtld-step-nodebugsym.c
> @@ -0,0 +1,25 @@
> +/* This testcase is part of GDB, the GNU debugger.
> +
> + Copyright 2022 Free Software Foundation, Inc.
> +
> + 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, see <http://www.gnu.org/licenses/>. */
> +
> +#include <stdio.h>
> +
> +int
> +main (void)
> +{
> + printf ("hello wolrd");
> + return 0;
> +}
> diff --git a/gdb/testsuite/gdb.base/rtld-step-nodebugsym.exp b/gdb/testsuite/gdb.base/rtld-step-nodebugsym.exp
> new file mode 100644
> index 00000000000..3bc6929102c
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/rtld-step-nodebugsym.exp
> @@ -0,0 +1,31 @@
> +# Copyright 2022 Free Software Foundation, Inc.
> +
> +# 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, see <http://www.gnu.org/licenses/>.
> +
> +# Test stepping through a runtime loader / dynamic linker (RTLD) without
> +# debug info.
> +
> +standard_testfile
> +
> +if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile} [list]] } {
I think explicitly saying {nodebug} instead of [list] would make this
test clearer.
With this fixed, you get my
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
Cheers,
Bruno
> + return
> +}
> +
> +if { ![runto_main] } {
> + return
> +}
> +
> +gdb_test "step" "Single stepping until exit from function.*"
> +
> +gdb_continue_to_end "" continue 1
>
> base-commit: b0119424d19afcf80997ad5f3128d7ec68e1fafa
>> +if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}
>> [list]] } {
>
> I think explicitly saying {nodebug} instead of [list] would make this
> test clearer.
You are absolutely right! I have done this change locally.
Best,
Lancelot.
On Fri, 4 Nov 2022 18:26:34 +0000
Lancelot SIX <lancelot.six@amd.com> wrote:
> Commit be6276e0aed "Allow debugging of runtime loader / dynamic linker"
> introduced a small regression when stepping into the runtime loader /
> dynamic linker from function we do not have debug information for. This
> is reported in PR/29747.
>
> This can be shown by the following example (given by Simon Marchi in
> buzilla bug report):
>
> $ cat test.c
> #include <stdio.h>
>
> int main()
> {
> printf("Hi\n");
> return 0;
> }
> $ gcc test.c -O0 -o test
> $ ./gdb -q -nx --data-directory=data-directory test -ex start -ex s
> Reading symbols from test...
> (No debugging symbols found in test)
> Temporary breakpoint 1 at 0x1151
> Starting program: .../binutils-gdb/gdb/test
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
>
> Temporary breakpoint 1, 0x0000555555555151 in main ()
> Single stepping until exit from function main,
> which has no line number information.
> /home/smarchi/src/binutils-gdb/gdb/infrun.c:6960:64: runtime error: member call on null pointer of type 'struct symbol'
>
> The crash happens here:
>
> #0 __sanitizer::Die () at ../../../../src/libsanitizer/sanitizer_common/sanitizer_termination.cpp:50
> #1 0x00007ffff5dd7128 in __ubsan::__ubsan_handle_type_mismatch_v1_abort (Data=<optimized out>, Pointer=<optimized out>) at ../../../../src/libsanitizer/ubsan/ubsan_handlers.cpp:148
> #2 0x000055556183e1a7 in process_event_stop_test (ecs=0x7fffffffccd0) at .../binutils-gdb/gdb/infrun.c:6960
> #3 0x0000555561838ea4 in handle_signal_stop (ecs=0x7fffffffccd0) at .../binutils-gdb/gdb/infrun.c:6615
> #4 0x000055556182f77b in handle_inferior_event (ecs=0x7fffffffccd0) at .../binutils-gdb/gdb/infrun.c:5866
>
> When evaluating:
>
> 6956 if (execution_direction != EXEC_REVERSE
> 6957 && ecs->event_thread->control.step_over_calls == STEP_OVER_UNDEBUGGABLE
> 6958 && in_solib_dynsym_resolve_code (ecs->event_thread->stop_pc ())
> 6959 && !in_solib_dynsym_resolve_code (
> 6961 ecs->event_thread->control.step_start_function->value_block ()
> 6962 ->entry_pc ()))
>
> we dereference, ecs->event_thread->control.step_start_function which is
> nullptr.
>
> This patch changes this condition so it evaluates to true if
> ecs->event_thread->control.step_start_function is nullptr since this
> matches the behaviour before be6276e0aed.
Thanks for fixing this!
I see that Bruno has asked for the test case to be tweaked and your
reply that you've fixed it in your local sources. That being the
case...
Approved-By: Kevin Buettner <kevinb@redhat.com>
Kevin
> Thanks for fixing this!
>
> I see that Bruno has asked for the test case to be tweaked and your
> reply that you've fixed it in your local sources. That being the
> case...
>
> Approved-By: Kevin Buettner <kevinb@redhat.com>
>
> Kevin
>
Thanks for the review.
I'll push this shortly, including the change requested by Bruno and a
typo fix in the testcase.
Best,
Lancelot.
@@ -6956,9 +6956,10 @@ process_event_stop_test (struct execution_control_state *ecs)
if (execution_direction != EXEC_REVERSE
&& ecs->event_thread->control.step_over_calls == STEP_OVER_UNDEBUGGABLE
&& in_solib_dynsym_resolve_code (ecs->event_thread->stop_pc ())
- && !in_solib_dynsym_resolve_code (
- ecs->event_thread->control.step_start_function->value_block ()
- ->entry_pc ()))
+ && (ecs->event_thread->control.step_start_function == nullptr
+ || !in_solib_dynsym_resolve_code (
+ ecs->event_thread->control.step_start_function->value_block ()
+ ->entry_pc ())))
{
CORE_ADDR pc_after_resolver =
gdbarch_skip_solib_resolver (gdbarch, ecs->event_thread->stop_pc ());
new file mode 100644
@@ -0,0 +1,25 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2022 Free Software Foundation, Inc.
+
+ 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, see <http://www.gnu.org/licenses/>. */
+
+#include <stdio.h>
+
+int
+main (void)
+{
+ printf ("hello wolrd");
+ return 0;
+}
new file mode 100644
@@ -0,0 +1,31 @@
+# Copyright 2022 Free Software Foundation, Inc.
+
+# 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, see <http://www.gnu.org/licenses/>.
+
+# Test stepping through a runtime loader / dynamic linker (RTLD) without
+# debug info.
+
+standard_testfile
+
+if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile} [list]] } {
+ return
+}
+
+if { ![runto_main] } {
+ return
+}
+
+gdb_test "step" "Single stepping until exit from function.*"
+
+gdb_continue_to_end "" continue 1