From: Lancelot SIX <lancelot.six@amd.com>
To: <gdb-patches@sourceware.org>
Cc: <kevinb@redhat.com>, <lsix@lancelotsix.com>,
Lancelot SIX <lancelot.six@amd.com>
Subject: [PATCH] Fix stepping in rtld without debug symbol
Date: Fri, 4 Nov 2022 18:26:34 +0000 [thread overview]
Message-ID: <20221104182634.3726422-1-lancelot.six@amd.com> (raw)
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
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]] } {
+ return
+}
+
+if { ![runto_main] } {
+ return
+}
+
+gdb_test "step" "Single stepping until exit from function.*"
+
+gdb_continue_to_end "" continue 1
base-commit: b0119424d19afcf80997ad5f3128d7ec68e1fafa
--
2.34.1
next reply other threads:[~2022-11-04 18:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-04 18:26 Lancelot SIX [this message]
2022-11-07 9:43 ` Bruno Larsen
2022-11-07 10:21 ` Lancelot SIX
2022-11-09 16:22 ` Kevin Buettner
2022-11-09 18:43 ` Lancelot SIX
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