From patchwork Wed Nov 16 18:56:24 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Aktemur, Tankut Baris" X-Patchwork-Id: 60713 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 2BCBC395C06F for ; Wed, 16 Nov 2022 18:57:17 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 2BCBC395C06F DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1668625037; bh=0MRmf/4xXPN11ynxiDcO1hp+gu+qR3ZBJ06/eHQzYnE=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=pWTmPm0c2xQCCswv1f0HmqeIrpSfq8mqboy81LVNlM0T0M6oE2d9raaG9gW2wr2MT FpU90coFv/iWdApMWT2/h+Fr9BkN+uMwCsLd0gv9w/rtapcWQ5E4FPlDFKEL6BAwa7 G5TMLz0UGJD7qnFQbzB3gYRl3yj7adEc8S6OB5lY= X-Original-To: gdb-patches@sourceware.org Delivered-To: gdb-patches@sourceware.org Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by sourceware.org (Postfix) with ESMTPS id B996E395C063 for ; Wed, 16 Nov 2022 18:56:50 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org B996E395C063 X-IronPort-AV: E=McAfee;i="6500,9779,10533"; a="310261733" X-IronPort-AV: E=Sophos;i="5.96,169,1665471600"; d="scan'208";a="310261733" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Nov 2022 10:56:46 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10533"; a="708280002" X-IronPort-AV: E=Sophos;i="5.96,169,1665471600"; d="scan'208";a="708280002" Received: from ultl2604.iul.intel.com (HELO localhost) ([172.28.48.47]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Nov 2022 10:56:46 -0800 To: gdb-patches@sourceware.org Subject: [PATCH] gdb/infrun: reset thread control's step info in end_stepping_range Date: Wed, 16 Nov 2022 19:56:24 +0100 Message-Id: <20221116185624.3770349-1-tankut.baris.aktemur@intel.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Spam-Status: No, score=-8.6 required=5.0 tests=AC_FROM_MANY_DOTS, BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Tankut Baris Aktemur via Gdb-patches From: "Aktemur, Tankut Baris" Reply-To: Tankut Baris Aktemur Errors-To: gdb-patches-bounces+patchwork=sourceware.org@sourceware.org Sender: "Gdb-patches" Suppose we have two inferiors on an all-stop target with schedule-multi set on: $ gdb -q (gdb) target extended-remote | gdbserver --multi - Remote debugging using | gdbserver --multi - Remote debugging using stdio (gdb) file /temp/test Reading symbols from /temp/test... (gdb) set remote exec-file /temp/test (gdb) start Temporary breakpoint 1 at 0x115c: file test.c, line 8. Starting program: /temp/test stdin/stdout redirected Process /temp/test created; pid = 864027 ... Temporary breakpoint 1, main (argc=1, argv=0x7fffffffd218) at test.c:8 8 foo(); (gdb) add-inferior [New inferior 2] Added inferior 2 on connection 1 (extended-remote | gdbserver --multi -) (gdb) inferior 2 [Switching to inferior 2 [] ()] (gdb) file /temp/test Reading symbols from /temp/test... (gdb) set remote exec-file /temp/test (gdb) tbreak 2 Temporary breakpoint 2 at 0x555555555131: /temp/test.c:2. (2 locations) (gdb) run Starting program: /temp/test stdin/stdout redirected Process /temp/test created; pid = 864430 ... Thread 2.1 "test" hit Temporary breakpoint 2, foo () at test.c:2 2 int a = 42; (gdb) set schedule-multi on (gdb) At this point, detaching the first inferior works fine: (gdb) detach inferiors 1 Detaching from program: /temp/test, process 858904 Detaching from process 858904 [Inferior 1 (process 858904) detached] (gdb) info inferiors Num Description Connection Executable 1 1 (extended-remote | gdbserver --multi -) /temp/test * 2 process 858925 1 (extended-remote | gdbserver --multi -) /temp/test (gdb) Let us now repeat exactly the same scenario, but before detaching, we make the current thread single-step an instruction: ... Thread 2.1 "test" hit Temporary breakpoint 2, foo () at test.c:2 2 int a = 42; (gdb) stepi 3 int b = 43; (gdb) detach inferiors 1 Detaching from program: /temp/test, process 876580 Detaching from process 876580 gdbserver: Couldn't reap LWP 876580 while detaching: No child processes [Inferior 1 (process 876580) detached] (gdb) 3 int b = 43; There is a mysterious line info output. Running the scenario with infrun debug logs reveals more information. ... Thread 2.1 "test" hit Temporary breakpoint 2, foo () at test.c:2 2 int a = 42; (gdb) stepi 3 int b = 43; (gdb) set debug infrun on (gdb) detach inferiors 1 [infrun] scoped_disable_commit_resumed: reason=detaching Detaching from program: /temp/test, process 872445 Detaching from process 872445 gdbserver: Couldn't reap LWP 872445 while detaching: No child processes [Inferior 1 (process 872445) detached] [infrun] start_step_over: enter [infrun] start_step_over: stealing global queue of threads to step, length = 0 [infrun] operator(): step-over queue now empty [infrun] start_step_over: exit [infrun] restart_stepped_thread: switching back to stepped thread (stepping) [infrun] keep_going_stepped_thread: resuming previously stepped thread [infrun] keep_going_stepped_thread: expected thread advanced also (0x555555555131 -> 0x555555555138) [infrun] clear_step_over_info: clearing step over info [infrun] do_target_resume: resume_ptid=-1.0.0, step=0, sig=GDB_SIGNAL_0 [infrun] infrun_async: enable=1 [infrun] reset: reason=detaching [infrun] maybe_set_commit_resumed_all_targets: enabling commit-resumed for target extended-remote [infrun] maybe_call_commit_resumed_all_targets: calling commit_resumed for target extended-remote (gdb) [infrun] fetch_inferior_event: enter [infrun] scoped_disable_commit_resumed: reason=handling event [infrun] do_target_wait: Found 2 inferiors, starting at #0 [infrun] random_pending_event_thread: None found. [infrun] print_target_wait_results: target_wait (-1.0.0 [process -1], status) = [infrun] print_target_wait_results: 872464.872464.0 [Thread 872464.872464], [infrun] print_target_wait_results: status->kind = STOPPED, sig = GDB_SIGNAL_TRAP [infrun] handle_inferior_event: status->kind = STOPPED, sig = GDB_SIGNAL_TRAP [infrun] context_switch: Switching context from 0.0.0 to 872464.872464.0 [infrun] handle_signal_stop: stop_pc=0x555555555138 [infrun] handle_signal_stop: [872464.872464.0] hit its single-step breakpoint [infrun] handle_signal_stop: delayed software breakpoint trap, ignoring [infrun] process_event_stop_test: stepi/nexti [infrun] stop_waiting: stop_waiting 3 int b = 43; [infrun] infrun_async: enable=0 [infrun] reset: reason=handling event [infrun] maybe_set_commit_resumed_all_targets: not requesting commit-resumed for target extended-remote, no resumed threads [infrun] fetch_inferior_event: exit GDB attempted to do a step-over for the current thread. This takes us to the commit that introduced restarting step-overs: commit 408f66864a1a823591b26420410c982174c239a2 Author: Pedro Alves Date: Mon Jan 11 20:01:58 2021 +0000 detach in all-stop with threads running A following patch will add a testcase that has a number of threads constantly stepping over a breakpoint, and then has GDB detach the process, while threads are running. If we have more than one inferior running, and we detach from just one of the inferiors, we expect that the remaining inferior continues running. However, in all-stop, if GDB needs to pause the target for the detach, nothing is re-resuming the other inferiors after the detach. "info threads" shows the threads as running, but they really aren't. This fixes it. However, the thread that was resumed for step-over in our scenario did not have an interrupted step-over; it had completed its stepi already. More debugging reveals that the thread is resumed because of the following two conditions in `restart_stepped_thread`: if (tp->control.trap_expected) { infrun_debug_printf ("switching back to stepped thread (step-over)"); if (keep_going_stepped_thread (tp)) return true; } and if (tp->control.step_range_end) { infrun_debug_printf ("switching back to stepped thread (stepping)"); if (keep_going_stepped_thread (tp)) return true; } The root cause of the problem is, the 'trap_expected' and the 'step_range_end' fields of the thread's control remain set even after the "stepi" command completes. We fix the problem by clearing the control fields when stepping completes. We also add a regression test. Regression-tested using the default, native-gdbserver, and native-extended-gdbserver board files. --- gdb/infrun.c | 3 ++ gdb/testsuite/gdb.multi/detach-stepi.c | 30 +++++++++++ gdb/testsuite/gdb.multi/detach-stepi.exp | 66 ++++++++++++++++++++++++ 3 files changed, 99 insertions(+) create mode 100644 gdb/testsuite/gdb.multi/detach-stepi.c create mode 100644 gdb/testsuite/gdb.multi/detach-stepi.exp diff --git a/gdb/infrun.c b/gdb/infrun.c index 6da46b75ac7..ef422f0e9e9 100644 --- a/gdb/infrun.c +++ b/gdb/infrun.c @@ -8314,6 +8314,9 @@ static void end_stepping_range (struct execution_control_state *ecs) { ecs->event_thread->control.stop_step = 1; + ecs->event_thread->control.trap_expected = 0; + ecs->event_thread->control.step_range_start = 0; + ecs->event_thread->control.step_range_end = 0; stop_waiting (ecs); } diff --git a/gdb/testsuite/gdb.multi/detach-stepi.c b/gdb/testsuite/gdb.multi/detach-stepi.c new file mode 100644 index 00000000000..d365645fb3f --- /dev/null +++ b/gdb/testsuite/gdb.multi/detach-stepi.c @@ -0,0 +1,30 @@ +/* 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 . */ + +void +a_function () +{ + int a = 42; +} + +int +main () +{ + int b = 43; + a_function (); + return 0; +} diff --git a/gdb/testsuite/gdb.multi/detach-stepi.exp b/gdb/testsuite/gdb.multi/detach-stepi.exp new file mode 100644 index 00000000000..28ef8c4f9f7 --- /dev/null +++ b/gdb/testsuite/gdb.multi/detach-stepi.exp @@ -0,0 +1,66 @@ +# 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 . + +# Test detaching from an inferior after a thread in another inferior +# completes a stepi. This is a regression test for a bug that was +# causing an inadvertent resume of the just-stepped thread. + +standard_testfile + +if {[use_gdb_stub]} { + untested "using gdb stub" + return 0 +} + +if {[prepare_for_testing "failed to prepare" $testfile $srcfile]} { + return -1 +} + +if {![runto_main]} { + return -1 +} + +delete_breakpoints + +# Setup inferior 2. +gdb_test "add-inferior" "Added inferior .*" \ + "add empty inferior" +gdb_test "inferior 2" "Switching to inferior .*" \ + "switch to inferior" + +gdb_load $binfile +runto "a_function" +gdb_test "info inferiors" + +# The bug for which this regression test is written appears in +# schedule-multi mode. +gdb_test_no_output "set schedule-multiple on" + +# Single-step the thread in Inferior 2, then detach Inferior 1. +gdb_test "info threads" ".*" "threads before stepi" +gdb_test "stepi" +gdb_test "info threads" ".*" "threads after stepi" + +gdb_test "set debug infrun on" +gdb_test_multiple "detach inferior 1" "" { + -re "resuming previously stepped thread.*$gdb_prompt" { + fail $gdb_test_name + } + -re "$gdb_prompt $" { + pass $gdb_test_name + } +}