From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm1-f46.google.com (mail-wm1-f46.google.com [209.85.128.46]) by sourceware.org (Postfix) with ESMTPS id 0B830384D3C8 for ; Mon, 12 Dec 2022 20:31:23 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 0B830384D3C8 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=palves.net Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-wm1-f46.google.com with SMTP id p13-20020a05600c468d00b003cf8859ed1bso6318382wmo.1 for ; Mon, 12 Dec 2022 12:31:22 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=gGfAPIWuIEaMs7gq8ZxbPw7qhFreRVjDmsjHNu4+iQA=; b=EWQaC6JfQyXc1Hu9f4yVMtASq8WVbRkNCd5s61rxrsKdgbbTV6OZ/JOximdkJMeKKU KQYwRM0ykNIZQMuPWSPHpir6iY3N+I1ZgZhBHfQjZLxl2f+QvYM051UQUWD/6GG0sI90 8EzPtO+TcO6pF2YkqoNo+YTbwhfJOVA/Go6rRw976K5DN9Fjg6D4Rt12/5J82oIgldAD snI2sGdG8FTFVrtr89NFngeIn+fF4qxyZOC7IcOb+2ZvvkJqsZXXES/RMdCiLuSuV0xq KOmy7Zkaf88RCyRJUqTFkbhQXx4KWL52p6BsyTggIzI6FifskVj/X2+VlBh9k5bGvtpH lLXQ== X-Gm-Message-State: ANoB5pl45OBhqa1z7NK2FwrnmJ/XVKMHA8dmPM8fbCXi71EPhyPb0r9w 3kDbFMS2BYx6+DCgdEwqrgHmMSfjxDuqrw== X-Google-Smtp-Source: AA0mqf7inJsmaRABKd+1jDtYeBLF2CtLG6kuGsZcMmkgIaGuMNCbF+SsLOIGMzaofugZvhK9lryHag== X-Received: by 2002:a05:600c:991:b0:3cf:aa48:23d4 with SMTP id w17-20020a05600c099100b003cfaa4823d4mr13809434wmp.25.1670877081846; Mon, 12 Dec 2022 12:31:21 -0800 (PST) Received: from localhost ([2001:8a0:f912:6700:afd9:8b6d:223f:6170]) by smtp.gmail.com with ESMTPSA id p4-20020a1c5444000000b003d1e051f671sm10239973wmi.9.2022.12.12.12.31.21 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Dec 2022 12:31:21 -0800 (PST) From: Pedro Alves To: gdb-patches@sourceware.org Subject: [PATCH 17/31] Introduce GDB_THREAD_OPTION_EXIT thread option, fix step-over-thread-exit Date: Mon, 12 Dec 2022 20:30:47 +0000 Message-Id: <20221212203101.1034916-18-pedro@palves.net> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20221212203101.1034916-1-pedro@palves.net> References: <20221212203101.1034916-1-pedro@palves.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-10.4 required=5.0 tests=BAYES_00,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,GIT_PATCH_0,HEADER_FROM_DIFFERENT_DOMAINS,KAM_DMARC_STATUS,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_PASS,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 List-Id: When stepping over a breakpoint with displaced stepping, GDB needs to be informed if the stepped thread exits, otherwise the displaced stepping buffer that was allocated to that thread leaks, and this can result in deadlock, with other threads waiting for their turn to displaced step, but their turn never comes. Similarly, when stepping over a breakpoint in line, GDB also needs to be informed if the stepped thread exits, so that is can clear the step over state and re-resume threads. This commit makes it possible for GDB to ask the target to report thread exit events for a given thread, using the new "thread options" mechanism introduced by a previous patch. This only adds the core bits. Following patches in the series will teach the Linux backends (native & gdbserver) to handle the GDB_THREAD_OPTION_EXIT option, and then a later patch will make use of these thread exit events to clean up displaced stepping and inline stepping state properly. Change-Id: I96b719fdf7fee94709e98bb3a90751d8134f3a38 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27338 --- gdb/infrun.c | 15 ++++++++++----- gdb/remote.c | 9 +++++++++ gdb/target/target.c | 1 + gdb/target/target.h | 4 ++++ 4 files changed, 24 insertions(+), 5 deletions(-) diff --git a/gdb/infrun.c b/gdb/infrun.c index 6fdffb31884..e47e3c688e7 100644 --- a/gdb/infrun.c +++ b/gdb/infrun.c @@ -2445,24 +2445,29 @@ do_target_resume (ptid_t resume_ptid, bool step, enum gdb_signal sig) else target_pass_signals (signal_pass); - /* Request that the target report thread-{created,cloned} events in - the following situations: + /* Request that the target report thread-{created,cloned,exited} + events in the following situations: - If we are performing an in-line step-over-breakpoint, then we will remove a breakpoint from the target and only run the current thread. We don't want any new thread (spawned by the - step) to start running, as it might miss the breakpoint. + step) to start running, as it might miss the breakpoint. We + need to clear the step-over state if the stepped thread exits, + so we also enable thread-exit events. - If we are stepping over a breakpoint out of line (displaced stepping) then we won't remove a breakpoint from the target, but, if the step spawns a new clone thread, then we will need to fixup the $pc address in the clone child too, so we need it - to start stopped. + to start stopped. We need to release the displaced stepping + buffer if the stepped thread exits, so we also enable + thread-exit events. */ if (step_over_info_valid_p () || displaced_step_in_progress_thread (tp)) { - gdb_thread_options options = GDB_THREAD_OPTION_CLONE; + gdb_thread_options options + = GDB_THREAD_OPTION_CLONE | GDB_THREAD_OPTION_EXIT; if (target_supports_set_thread_options (options)) tp->set_thread_options (options); else diff --git a/gdb/remote.c b/gdb/remote.c index f7ab8523fd5..0d2b7c09a07 100644 --- a/gdb/remote.c +++ b/gdb/remote.c @@ -3998,6 +3998,15 @@ remote_target::update_thread_list () if (has_single_non_exited_thread (tp->inf)) continue; + /* Do not remove the thread if we've requested to be + notified of its exit. For example, the thread may be + displaced stepping, infrun will need to handle the + exit event, and displaced stepping info is recorded + in the thread object. If we deleted the thread now, + we'd lose that info. */ + if ((tp->thread_options () & GDB_THREAD_OPTION_EXIT) != 0) + continue; + /* Not found. */ delete_thread (tp); } diff --git a/gdb/target/target.c b/gdb/target/target.c index 453167a2ad4..2dc033e63b7 100644 --- a/gdb/target/target.c +++ b/gdb/target/target.c @@ -196,6 +196,7 @@ to_string (gdb_thread_options options) { static constexpr gdb_thread_options::string_mapping mapping[] = { MAP_ENUM_FLAG (GDB_THREAD_OPTION_CLONE), + MAP_ENUM_FLAG (GDB_THREAD_OPTION_EXIT), }; return options.to_string (mapping); } diff --git a/gdb/target/target.h b/gdb/target/target.h index 139e371e8d8..4e8839c5667 100644 --- a/gdb/target/target.h +++ b/gdb/target/target.h @@ -34,6 +34,10 @@ enum gdb_thread_option : unsigned /* Tell the target to report TARGET_WAITKIND_THREAD_CLONED events for the thread. */ GDB_THREAD_OPTION_CLONE = 1 << 0, + + /* Tell the target to report TARGET_WAITKIND_THREAD_EXIT events for + the thread. */ + GDB_THREAD_OPTION_EXIT = 1 << 1, }; DEF_ENUM_FLAGS_TYPE (enum gdb_thread_option, gdb_thread_options); -- 2.36.0