Step over exit with reinsert breakpoints
This patch fixes a GDBserver crash when one thread is stepping over a syscall instruction which is exit. Step-over isn't finished due to the exit, but GDBserver doesn't clean up the state of step-over, so in the wait next time, GDBserver will wait on step_over_bkpt, which is already exited, and GDBserver crashes because 'requested_child' is NULL. See gdbserver logs below, Need step over [LWP 14858]? yes, found breakpoint at 0x2aaaaad91307^M proceed_all_lwps: found thread 14858 needing a step-over^M Starting step-over on LWP 14858. Stopping all threads^M >>>> entering void stop_all_lwps(int, lwp_info*) .... <<<< exiting void stop_all_lwps(int, lwp_info*)^M Done stopping all threads for step-over.^M pc is 0x2aaaaad91307^M Writing 0f to 0x2aaaaad91307 in process 14858^M Could not find fast tracepoint jump at 0x2aaaaad91307 in list (uninserting).^M pending reinsert at 0x2aaaaad91307^M step from pc 0x2aaaaad91307^M Resuming lwp 14858 (step, signal 0, stop not expected)^M # Start step-over for LWP 14858 >>>> entering ptid_t linux_wait_1(ptid_t, target_waitstatus*, int) .... LLFE: 14858 exited. ... <<<< exiting ptid_t linux_wait_1(ptid_t, target_waitstatus*, int) # LWP 14858 exited ..... >>>> entering ptid_t linux_wait_1(ptid_t, target_waitstatus*, int)^M linux_wait_1: [<all threads>]^M step_over_bkpt set [LWP 14858.14858], doing a blocking wait # but step_over_bkpt is still LWP 14858, which is wrong The fix is to finish step-over if it is ongoing, and unsuspend other threads. Without the fix in linux-low.c, GDBserver will crash in with running gdb.base/step-over-exit.exp. gdb/gdbserver: 2016-06-17 Yao Qi <yao.qi@linaro.org> * linux-low.c (unsuspend_all_lwps): Declare. (linux_low_filter_event): If thread exited, call finish_step_over. If step-over is finished, unsuspend other threads. gdb/testsuite: 2016-06-17 Yao Qi <yao.qi@linaro.org> * gdb.base/step-over-exit.c: New. * gdb.base/step-over-exit.exp: New.
This commit is contained in:
parent
8376a3cbf7
commit
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@ -1,3 +1,9 @@
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2016-06-17 Yao Qi <yao.qi@linaro.org>
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* linux-low.c (unsuspend_all_lwps): Declare.
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(linux_low_filter_event): If thread exited, call finish_step_over.
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If step-over is finished, unsuspend other threads.
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2016-06-17 Yao Qi <yao.qi@linaro.org>
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* linux-low.c (linux_resume_one_lwp_throw): Assert
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@ -252,6 +252,7 @@ static void linux_resume_one_lwp (struct lwp_info *lwp,
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static void linux_resume (struct thread_resume *resume_info, size_t n);
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static void stop_all_lwps (int suspend, struct lwp_info *except);
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static void unstop_all_lwps (int unsuspend, struct lwp_info *except);
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static void unsuspend_all_lwps (struct lwp_info *except);
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static int linux_wait_for_event_filtered (ptid_t wait_ptid, ptid_t filter_ptid,
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int *wstat, int options);
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static int linux_wait_for_event (ptid_t ptid, int *wstat, int options);
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@ -2357,6 +2358,13 @@ linux_low_filter_event (int lwpid, int wstat)
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{
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if (debug_threads)
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debug_printf ("LLFE: %d exited.\n", lwpid);
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if (finish_step_over (child))
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{
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/* Unsuspend all other LWPs, and set them back running again. */
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unsuspend_all_lwps (child);
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}
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/* If there is at least one more LWP, then the exit signal was
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not the end of the debugged application and should be
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ignored, unless GDB wants to hear about thread exits. */
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@ -1,3 +1,8 @@
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2016-06-17 Yao Qi <yao.qi@linaro.org>
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* gdb.base/step-over-exit.c: New.
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* gdb.base/step-over-exit.exp: New.
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2016-06-17 Yan-Ting Lin <currygt52@gmail.com>
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* gdb.base/float.exp: Add target check for nds32*-*-*.
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@ -0,0 +1,50 @@
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/* This testcase is part of GDB, the GNU debugger.
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Copyright 2016 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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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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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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static void
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marker (void)
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{}
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int
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main (void)
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{
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int pid;
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pid = fork ();
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if (pid == 0) /* child */
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{
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_exit (0);
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}
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else
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{
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}
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pid = fork ();
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if (pid == 0) /* child */
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{
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marker ();
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_exit (0);
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}
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else
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{
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marker ();
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}
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}
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@ -0,0 +1,127 @@
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# Copyright 2016 Free Software Foundation, Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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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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standard_testfile
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# Test a thread is doing step-over a syscall instruction which is exit,
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# and GDBserver should cleanup its state of step-over properly.
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set syscall_insn ""
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# Define the syscall instruction for each target.
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if { [istarget "i\[34567\]86-*-linux*"] || [istarget "x86_64-*-linux*"] } {
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set syscall_insn "\[ \t\](int|syscall|sysenter)\[ \t\]"
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} elseif { [istarget "aarch64*-*-linux*"] || [istarget "arm*-*-linux*"] } {
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set syscall_insn "\[ \t\](swi|svc)\[ \t\]"
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} else {
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unsupported "unknown syscall instruction"
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return -1
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}
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if {[prepare_for_testing $testfile.exp $testfile $srcfile debug]} {
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untested $testfile.exp
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return -1
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}
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# Start with a fresh gdb.
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clean_restart ${testfile}
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if ![runto_main] {
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fail "Can't run to main"
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return -1
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}
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gdb_test "set follow-fork-mode child"
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gdb_test "set detach-on-fork off"
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# Step 1, find the syscall instruction address.
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gdb_test "break _exit" "Breakpoint $decimal at .*"
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# Hit the breakpoint on _exit. The address of syscall insn is recorded.
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gdb_test "continue" \
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"Continuing\\..*Breakpoint $decimal.*_exit \\(.*\\).*" \
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"continue to exit"
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gdb_test "display/i \$pc" ".*"
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# Single step until we see a syscall insn or we reach the
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# upper bound of loop iterations.
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set msg "find syscall insn in exit"
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set steps 0
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set max_steps 1000
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gdb_test_multiple "stepi" $msg {
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-re ".*$syscall_insn.*$gdb_prompt $" {
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pass $msg
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}
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-re "x/i .*=>.*\r\n$gdb_prompt $" {
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incr steps
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if {$steps == $max_steps} {
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fail $msg
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} else {
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send_gdb "stepi\n"
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exp_continue
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}
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}
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}
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if {$steps == $max_steps} {
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return
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}
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# Remove the display
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gdb_test_no_output "delete display 1"
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set syscall_insn_addr [get_hexadecimal_valueof "\$pc" "0"]
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gdb_test "continue" "exited normally.*" "continue to end, first time"
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gdb_test "inferior 1" ".*Switching to inferior 1.*" \
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"switch back to inferior 1, first time"
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delete_breakpoints
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gdb_test "break marker"
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gdb_test "continue" "Continuing\\..*Breakpoint $decimal, .*" \
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"continue to marker, first time"
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# Step 2, create a breakpoint which evaluates false, and force it
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# evaluated on the target side.
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set test "set breakpoint condition-evaluation target"
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gdb_test_multiple $test $test {
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-re "warning: Target does not support breakpoint condition evaluation.\r\nUsing host evaluation mode instead.\r\n$gdb_prompt $" {
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# Target doesn't support breakpoint condition evaluation
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# on its side, but it is no harm to run the test.
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}
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-re "^$test\r\n$gdb_prompt $" {
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}
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}
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gdb_test "break \*$syscall_insn_addr if main == 0" \
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"Breakpoint \[0-9\]* at .*"
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# Resume the child process, and the step-over is being done.
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gdb_test "continue" "exited normally.*" "continue to end, second time"
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gdb_test "inferior 1" ".*Switching to inferior 1.*" \
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"switch back to inferior 1, second time"
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# Switch back to the parent process, continue to the marker to
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# test GDBserver's state is still correct.
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gdb_test "continue" "Continuing\\..*Breakpoint $decimal, .*" \
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"continue to marker, second time"
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