From patchwork Tue Dec 18 11:22:28 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pavel Dovgalyuk X-Patchwork-Id: 10735499 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 368F26C2 for ; Tue, 18 Dec 2018 11:37:25 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 24B0A26223 for ; Tue, 18 Dec 2018 11:37:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 180202A5E0; Tue, 18 Dec 2018 11:37:25 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 7A65326223 for ; Tue, 18 Dec 2018 11:37:24 +0000 (UTC) Received: from localhost ([::1]:53311 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gZDgh-0007Cz-Ah for patchwork-qemu-devel@patchwork.kernel.org; Tue, 18 Dec 2018 06:37:23 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46951) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gZDSJ-0003KP-A5 for qemu-devel@nongnu.org; Tue, 18 Dec 2018 06:22:33 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gZDSF-0006PA-Oe for qemu-devel@nongnu.org; Tue, 18 Dec 2018 06:22:31 -0500 Received: from mail.ispras.ru ([83.149.199.45]:55706) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gZDSF-0006Nc-AD for qemu-devel@nongnu.org; Tue, 18 Dec 2018 06:22:27 -0500 Received: from [127.0.1.1] (unknown [85.142.117.226]) by mail.ispras.ru (Postfix) with ESMTPSA id BF53F54006A; Tue, 18 Dec 2018 14:22:25 +0300 (MSK) From: Pavel Dovgalyuk To: qemu-devel@nongnu.org Date: Tue, 18 Dec 2018 14:22:28 +0300 Message-ID: <20181218112228.11727.28224.stgit@pasha-VirtualBox> In-Reply-To: <20181218112056.11727.96529.stgit@pasha-VirtualBox> References: <20181218112056.11727.96529.stgit@pasha-VirtualBox> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 83.149.199.45 Subject: [Qemu-devel] [PATCH v8 16/20] gdbstub: add reverse continue support in replay mode X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, peter.maydell@linaro.org, war2jordan@live.com, pavel.dovgaluk@ispras.ru, pbonzini@redhat.com, crosthwaite.peter@gmail.com, ciro.santilli@gmail.com, jasowang@redhat.com, quintela@redhat.com, armbru@redhat.com, mreitz@redhat.com, alex.bennee@linaro.org, maria.klimushenkova@ispras.ru, mst@redhat.com, kraxel@redhat.com, boost.lists@gmail.com, thomas.dullien@googlemail.com, dovgaluk@ispras.ru, artem.k.pisarenko@gmail.com, dgilbert@redhat.com, rth@twiddle.net Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP This patch adds support of the reverse continue operation for gdbstub. Reverse continue finds the last breakpoint that would happen in normal execution from the beginning to the current moment. Implementation of the reverse continue replays the execution twice: to find the breakpoints that were hit and to seek to the last breakpoint. Reverse continue loads the previous snapshot and tries to find the breakpoint since that moment. If there are no such breakpoints, it proceeds to the earlier snapshot, and so on. When no breakpoints or watchpoints were hit at all, execution stops at the beginning of the replay log. Signed-off-by: Pavel Dovgalyuk --- cpus.c | 3 ++ exec.c | 1 + gdbstub.c | 10 ++++++- include/sysemu/replay.h | 6 ++++ replay/replay-debugging.c | 69 +++++++++++++++++++++++++++++++++++++++++++++ stubs/replay.c | 5 +++ 6 files changed, 93 insertions(+), 1 deletion(-) diff --git a/cpus.c b/cpus.c index 610a6dd..150cbb3 100644 --- a/cpus.c +++ b/cpus.c @@ -1110,6 +1110,9 @@ static void cpu_handle_guest_debug(CPUState *cpu) cpu->stopped = true; } else { if (!cpu->singlestep_enabled) { + /* Report about the breakpoint and + make a single step to skip it */ + replay_breakpoint(); cpu_single_step(cpu, SSTEP_ENABLE); } else { cpu_single_step(cpu, 0); diff --git a/exec.c b/exec.c index c92eba5..704b0f6 100644 --- a/exec.c +++ b/exec.c @@ -2742,6 +2742,7 @@ static void check_watchpoint(int offset, int len, MemTxAttrs attrs, int flags) if (replay_running_debug()) { /* Don't process the watchpoints when we are in a reverse debugging operation. */ + replay_breakpoint(); return; } if (flags == BP_MEM_READ) { diff --git a/gdbstub.c b/gdbstub.c index e232f0c..ba66ed9 100644 --- a/gdbstub.c +++ b/gdbstub.c @@ -1110,6 +1110,14 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf) put_packet(s, "E14"); break; } + case 'c': + if (replay_reverse_continue()) { + gdb_continue(s); + return RS_IDLE; + } else { + put_packet(s, "E14"); + break; + } default: goto unknown_command; } @@ -1380,7 +1388,7 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf) pstrcat(buf, sizeof(buf), ";qXfer:features:read+"); } if (replay_mode == REPLAY_MODE_PLAY) { - pstrcat(buf, sizeof(buf), ";ReverseStep+"); + pstrcat(buf, sizeof(buf), ";ReverseStep+;ReverseContinue+"); } put_packet(s, buf); break; diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h index 73bf5fc..05cb40a 100644 --- a/include/sysemu/replay.h +++ b/include/sysemu/replay.h @@ -77,9 +77,15 @@ const char *replay_get_filename(void); Used by gdbstub for backwards debugging. Returns true on success. */ bool replay_reverse_step(void); +/* Start searching the last breakpoint/watchpoint. + Used by gdbstub for backwards debugging. + Returns true if the process successfully started. */ +bool replay_reverse_continue(void); /* Returns true if replay module is processing reverse_continue or reverse_step request */ bool replay_running_debug(void); +/* Called in reverse debugging mode to collect breakpoint information */ +void replay_breakpoint(void); /* Processing the instructions */ diff --git a/replay/replay-debugging.c b/replay/replay-debugging.c index 6334d82..b43a008 100644 --- a/replay/replay-debugging.c +++ b/replay/replay-debugging.c @@ -22,6 +22,8 @@ #include "migration/snapshot.h" static bool replay_is_debugging; +static int64_t replay_last_breakpoint; +static int64_t replay_last_snapshot; bool replay_running_debug(void) { @@ -248,3 +250,70 @@ bool replay_reverse_step(void) return false; } + +static void replay_continue_end(void) +{ + replay_is_debugging = false; + vm_stop(RUN_STATE_DEBUG); + replay_break(-1LL, NULL, NULL); +} + +static void replay_continue_stop(void *opaque) +{ + Error *err = NULL; + if (replay_last_breakpoint != -1LL) { + replay_seek(replay_last_breakpoint, replay_stop_vm_debug, &err); + if (err) { + error_free(err); + replay_continue_end(); + } + return; + } + /* No breakpoints since the last snapshot. + Find previous snapshot and try again. */ + if (replay_last_snapshot != 0) { + replay_seek(replay_last_snapshot - 1, replay_continue_stop, &err); + if (err) { + error_free(err); + replay_continue_end(); + } + replay_last_snapshot = replay_get_current_step(); + return; + } else { + /* Seek to the very first step */ + replay_seek(0, replay_stop_vm_debug, &err); + if (err) { + error_free(err); + replay_continue_end(); + } + return; + } + replay_continue_end(); +} + +bool replay_reverse_continue(void) +{ + Error *err = NULL; + + assert(replay_mode == REPLAY_MODE_PLAY); + + if (replay_get_current_step() != 0) { + replay_seek(replay_get_current_step() - 1, replay_continue_stop, &err); + if (err) { + error_free(err); + return false; + } + replay_last_breakpoint = -1LL; + replay_is_debugging = true; + replay_last_snapshot = replay_get_current_step(); + return true; + } + + return false; +} + +void replay_breakpoint(void) +{ + assert(replay_mode == REPLAY_MODE_PLAY); + replay_last_breakpoint = replay_get_current_step(); +} diff --git a/stubs/replay.c b/stubs/replay.c index 521552f..ee64972 100644 --- a/stubs/replay.c +++ b/stubs/replay.c @@ -85,3 +85,8 @@ bool replay_reverse_step(void) { return false; } + +bool replay_reverse_continue(void) +{ + return false; +}