From patchwork Mon Nov 13 15:04:16 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pedro Alves X-Patchwork-Id: 79759 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 7F3BB395381B for ; Mon, 13 Nov 2023 15:07:50 +0000 (GMT) X-Original-To: gdb-patches@sourceware.org Delivered-To: gdb-patches@sourceware.org Received: from mail-wm1-f52.google.com (mail-wm1-f52.google.com [209.85.128.52]) by sourceware.org (Postfix) with ESMTPS id 03C233858C01 for ; Mon, 13 Nov 2023 15:05:35 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 03C233858C01 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=palves.net Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 03C233858C01 Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=209.85.128.52 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1699887937; cv=none; b=Op1yWub7+6rJy9Eb7ouCGopvYipuh1s3xWnAepT4OoGiMzzwbS1aeDWPFF/z4ON6Fxsc0yqYsAXkWf5POcbw87n+8KFb7sC8WVGiNBE5JhlU6ZMnby7HVNl/ITc6cwiiCK9oCpxlf2UVCDEjAt3WEH9uN0sM35KXdzDMfJGnB6A= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1699887937; c=relaxed/simple; bh=AV6K3KeQoS6Xt7B8pEGQVFcsta0VTgWNZpb7tXTkEvA=; h=From:To:Subject:Date:Message-Id:MIME-Version; b=gHkgXfLuyIudh3VgkGor62Dhc8j7N60NTFlhCpvUVBJtWyYXMGw0zNHnUgorwAa2k7CUnvKkqvJCW/OZgYeLBikUTxgwc5xBcDSwqEyYl6L9zx9lf92Ks+v1YjZKPgQfES/hIoW4LZ1aGcbadVemiz3T2v+Gel/6/pCYNAeFZ2U= ARC-Authentication-Results: i=1; server2.sourceware.org Received: by mail-wm1-f52.google.com with SMTP id 5b1f17b1804b1-407da05f05aso33755085e9.3 for ; Mon, 13 Nov 2023 07:05:34 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699887933; x=1700492733; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=K4NrHDtZrQaj4qIcb34kQSWX/5ursl3YU5GzPD/p0QE=; b=DoEMqF7TrU41H+7rs6JK4S3KVd+Dcdhh3PqFe26CzaP/kB5OtvSd4qkvCf0HIyp7t2 2b0p1v7Xb7tX4t5a6Y4HyF6wFsdGMNk9zNa4EcUWhDSe5fqe/S3sktkHgkzXeYz5ozxF BlzvxxsFyn+m1MXzlww15D/ohcsNsQKUOyGMzkHJ7NCO5o3FJYCjt/VUVT9piBWsymu+ lXWON8hZOMOs8XsrMTfAE1be2l13AokGEbYRwKaI+ufvsmdVdYfwmD+zJdKbzAz2dYzm egtPL75cHktxBMa0L0h57NRxic2xkadAbUa5fStl1LzYrvAgXmCY7WJXSMXPajxY6Uvk Y35Q== X-Gm-Message-State: AOJu0YxrdQ+fcszbs68SO5k9DbWQtZPy3sm5McHTYPip2IF84tAZuZCt qqkC/BIEESpHRBg+sa4AFzshmJFMrjU= X-Google-Smtp-Source: AGHT+IHnUbx6PbenqpITOyWnuPMpkxuLu03ZRuDnJUOhZH9mw8i4JJ6HC1eqwaX+Rqw/hB2sNsJqnw== X-Received: by 2002:a05:600c:35d2:b0:409:57ec:9d7e with SMTP id r18-20020a05600c35d200b0040957ec9d7emr5276369wmq.21.1699887933541; Mon, 13 Nov 2023 07:05:33 -0800 (PST) Received: from localhost ([2001:8a0:f91e:1a00:8060:1e54:fb28:9635]) by smtp.gmail.com with UTF8SMTPSA id z14-20020adff74e000000b0032f7865a4c7sm5599042wrp.21.2023.11.13.07.05.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Nov 2023 07:05:33 -0800 (PST) From: Pedro Alves To: gdb-patches@sourceware.org Cc: Andrew Burgess Subject: [FYI/pushed v4 14/25] Introduce GDB_THREAD_OPTION_EXIT thread option, fix step-over-thread-exit Date: Mon, 13 Nov 2023 15:04:16 +0000 Message-Id: <20231113150427.477431-15-pedro@palves.net> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231113150427.477431-1-pedro@palves.net> References: <20231113150427.477431-1-pedro@palves.net> MIME-Version: 1.0 X-Spam-Status: No, score=-10.0 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, T_SCC_BODY_TEXT_LINE 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: 2.1.30 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces+patchwork=sourceware.org@sourceware.org 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. Reviewed-By: Andrew Burgess 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 e1e761cf48f..0a189d0a485 100644 --- a/gdb/infrun.c +++ b/gdb/infrun.c @@ -2516,24 +2516,29 @@ 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 eb537fc48a5..ce5addade6f 100644 --- a/gdb/remote.c +++ b/gdb/remote.c @@ -4206,6 +4206,15 @@ 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 3af7d73df5a..58d0f63c872 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 2691f92e4ef..bad4daa22a1 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);