From patchwork Wed Apr 30 19:17:59 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Don Breazeal X-Patchwork-Id: 767 Return-Path: X-Original-To: siddhesh@wilcox.dreamhost.com Delivered-To: siddhesh@wilcox.dreamhost.com Received: from homiemail-mx21.g.dreamhost.com (peon2454.g.dreamhost.com [208.113.200.127]) by wilcox.dreamhost.com (Postfix) with ESMTP id CE14B360072 for ; Wed, 30 Apr 2014 12:18:28 -0700 (PDT) Received: by homiemail-mx21.g.dreamhost.com (Postfix, from userid 14314964) id 705B1145E983; Wed, 30 Apr 2014 12:18:28 -0700 (PDT) X-Original-To: gdb@patchwork.siddhesh.in Delivered-To: x14314964@homiemail-mx21.g.dreamhost.com Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by homiemail-mx21.g.dreamhost.com (Postfix) with ESMTPS id 272DC148682A for ; Wed, 30 Apr 2014 12:18:28 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-type; q=dns; s=default; b=Qyv+F /4mmwMHBWJ+OxI475CpTkpSl3acOQhIY4tYe7/8h63A29R8yq9M5ZnaZ2JA2nSFq Gg9JXiGU1AmB70Y38j/75389uJUcvR6DHppMZG8PnNPVUKNZjoee19LtqcP1fbSH MgCT5227S9h3zIKKeE/89pA8R/1OEr6nZ0FM1o= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-type; s=default; bh=XjAmGgKFr1h Tf9RwfWxC7dFzTyk=; b=vv2HdW/Ca1v5xcGmCnp3dpGNFCzV7pcpfudHK5dGd62 4iHr6zWMl9mlR/RWDW7Mgr63WrNTrB3a7rVAkqPHA7f2QAgf2QTgKG6Few5c5VqE en48qETkNY+hDkHjKCai2iB+bmLeRXRiEUhkux73MDSlS8csEYpDEdDRVthgAa0g = Received: (qmail 7173 invoked by alias); 30 Apr 2014 19:18:20 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 7146 invoked by uid 89); 30 Apr 2014 19:18:18 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.8 required=5.0 tests=AWL, BAYES_00 autolearn=ham version=3.3.2 X-HELO: relay1.mentorg.com Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 30 Apr 2014 19:18:15 +0000 Received: from svr-orw-fem-01.mgc.mentorg.com ([147.34.98.93]) by relay1.mentorg.com with esmtp id 1Wfa1E-0004yI-68 from donb@codesourcery.com for gdb-patches@sourceware.org; Wed, 30 Apr 2014 12:18:12 -0700 Received: from SVR-ORW-FEM-04.mgc.mentorg.com ([147.34.97.41]) by svr-orw-fem-01.mgc.mentorg.com over TLS secured channel with Microsoft SMTPSVC(6.0.3790.4675); Wed, 30 Apr 2014 12:18:12 -0700 Received: from build4-lucid-cs (147.34.91.1) by svr-orw-fem-04.mgc.mentorg.com (147.34.97.41) with Microsoft SMTP Server id 14.2.247.3; Wed, 30 Apr 2014 12:18:10 -0700 Received: by build4-lucid-cs (Postfix, from userid 1905) id F003040D71; Wed, 30 Apr 2014 12:18:10 -0700 (PDT) From: Don Breazeal To: CC: Don Breazeal Subject: [PATCH 1/4][REPOST] Remote Linux ptrace exit events Date: Wed, 30 Apr 2014 12:17:59 -0700 Message-ID: <1398885482-8449-2-git-send-email-donb@codesourcery.com> In-Reply-To: <1398885482-8449-1-git-send-email-donb@codesourcery.com> References: <1398885482-8449-1-git-send-email-donb@codesourcery.com> MIME-Version: 1.0 X-IsSubscribed: yes X-DH-Original-To: gdb@patchwork.siddhesh.in From: Don Breazeal [Reposting to eliminate unexpected attachment type.] This patch implements support for the extended ptrace event PTRACE_EVENT_EXIT on Linux. This is a preparatory patch for exec event support. The use of this event is entirely internal to gdbserver; these events are not reported to GDB or the user. If an existing thread is not the last thread in a process, its lwp entry is simply deleted, since this is what happens in the absence of exit events. If it is the last thread of a process, the wait status is set to the actual wait status of the thread, instead of the status that indicates the extended event, and the existing mechanisms for handling thread exit proceed as usual. The only purpose in using the exit events instead of the existing wait mechanisms is to ensure that the exit of a thread group leader is detected reliably when a non-leader thread calls exec. gdb/ 2014-04-02 Don Breazeal * common/linux-ptrace.c (linux_test_for_tracefork) [GDBSERVER]: Add support for PTRACE_EVENT_EXIT if the OS supports it. gdbserver/ 2014-04-02 Don Breazeal * linux-low.c (is_extended_waitstatus): New function. (is_extended_exit): New function. (handle_extended_wait): Change type from void to int, change wait status arg to pointer, add support for PTRACE_EVENT_EXIT. (get_stop_pc): Use is_extended_waitstatus instead of hardcoded shift operation. (get_detach_signal): Use is_extended_waitstatus instead of hardcoded shift operation. (linux_low_filter_event): Handle new return value from handle_extended_wait. Check for extended events as needed. Allow status arg to be modified. (linux_wait_for_event_filtered): Allow status arg to be modified. --- gdb/common/linux-ptrace.c | 42 ++++++++++++++++++- gdb/gdbserver/linux-low.c | 99 +++++++++++++++++++++++++++++++++++++++------ 2 files changed, 125 insertions(+), 16 deletions(-) diff --git a/gdb/common/linux-ptrace.c b/gdb/common/linux-ptrace.c index 7c1b78a..e3fc705 100644 --- a/gdb/common/linux-ptrace.c +++ b/gdb/common/linux-ptrace.c @@ -414,7 +414,7 @@ linux_test_for_tracefork (int child_pid) ret = ptrace (PTRACE_CONT, child_pid, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0); if (ret != 0) - warning (_("linux_test_for_tracefork: failed to resume child")); + warning (_("linux_test_for_tracefork: failed to resume child (a)")); ret = my_waitpid (child_pid, &status, 0); @@ -455,10 +455,46 @@ linux_test_for_tracefork (int child_pid) "failed to kill second child")); my_waitpid (second_pid, &status, 0); } + else + { + /* Fork events are not supported. */ + return; + } } else - warning (_("linux_test_for_tracefork: unexpected result from waitpid " - "(%d, status 0x%x)"), ret, status); + { + warning (_("linux_test_for_tracefork: unexpected result from waitpid " + "(%d, status 0x%x)"), ret, status); + return; + } + +#ifdef GDBSERVER + /* PTRACE_O_FORK is supported, so now test for PTRACE_O_TRACEEXIT. + First try to set the option. If this fails, we know for sure that + it is not supported. */ + ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0, + (PTRACE_TYPE_ARG4) PTRACE_O_TRACEEXIT); + if (ret != 0) + return; + + /* We don't know for sure that the feature is available; old + versions of PTRACE_SETOPTIONS ignored unknown options. So + see if the process exit will generate a PTRACE_EVENT_EXIT. */ + ret = ptrace (PTRACE_CONT, child_pid, (PTRACE_TYPE_ARG3) 0, + (PTRACE_TYPE_ARG4) 0); + if (ret != 0) + warning (_("linux_test_for_tracefork: failed to resume child (b)")); + + ret = my_waitpid (child_pid, &status, 0); + + /* Check if we received an exit event notification. */ + if (ret == child_pid && WIFSTOPPED (status) + && status >> 16 == PTRACE_EVENT_EXIT) + { + /* PTRACE_O_TRACEEXIT is supported. */ + current_ptrace_options |= PTRACE_O_TRACEEXIT; + } +#endif } /* Enable reporting of all currently supported ptrace events. */ diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c index 2d8d5f5..90e7b15 100644 --- a/gdb/gdbserver/linux-low.c +++ b/gdb/gdbserver/linux-low.c @@ -224,6 +224,7 @@ static void proceed_all_lwps (void); static int finish_step_over (struct lwp_info *lwp); static CORE_ADDR get_stop_pc (struct lwp_info *lwp); static int kill_lwp (unsigned long lwpid, int signo); +static int num_lwps (int pid); /* True if the low target can hardware single-step. Such targets don't need a BREAKPOINT_REINSERT_ADDR callback. */ @@ -367,13 +368,32 @@ linux_add_process (int pid, int attached) return proc; } +/* Check wait status for extended event */ + +static int +is_extended_waitstatus (int wstat) +{ + return wstat >> 16 != 0; +} + +/* Check wait status for extended event */ + +static int +is_extended_exit (int wstat) +{ + return wstat >> 16 == PTRACE_EVENT_EXIT; +} + /* Handle a GNU/Linux extended wait response. If we see a clone event, we need to add the new LWP to our list (and not report the - trap to higher layers). */ + trap to higher layers). This function returns non-zero if the + event should be ignored and we should wait again. The wait status + in WSTATP may be modified if an exit event occurred. */ -static void -handle_extended_wait (struct lwp_info *event_child, int wstat) +static int +handle_extended_wait (struct lwp_info *event_child, int *wstatp) { + int wstat = *wstatp; int event = wstat >> 16; struct thread_info *event_thr = get_lwp_thread (event_child); struct lwp_info *new_lwp; @@ -448,11 +468,54 @@ handle_extended_wait (struct lwp_info *event_child, int wstat) linux_resume_one_lwp (new_lwp, 0, WSTOPSIG (status), NULL); } + /* Enable extended events for the new thread. */ + linux_enable_event_reporting (new_pid); + /* Always resume the current thread. If we are stopping threads, it will have a pending SIGSTOP; we may as well collect it now. */ linux_resume_one_lwp (event_child, event_child->stepping, 0, NULL); + + /* Don't report the event. */ + return 1; + } + else if (event == PTRACE_EVENT_EXIT) + { + unsigned long exit_status; + unsigned long lwpid = lwpid_of (event_thr); + int ret; + + if (debug_threads) + debug_printf ("LHEW: Got exit event from LWP %ld\n", + lwpid_of (event_thr)); + + ptrace (PTRACE_GETEVENTMSG, lwpid_of (event_thr), (PTRACE_TYPE_ARG3) 0, + &exit_status); + + if (num_lwps (pid_of (event_thr)) > 1) + { + /* If there is at least one more LWP, then the program still + exists and the exit should not be reported to GDB. */ + delete_lwp (event_child); + ret = 1; + } + else + { + /* Set the exit status to the actual exit status, so normal + WIFEXITED/WIFSIGNALLED processing and reporting for the + last lwp in the process can proceed from here. */ + *wstatp = exit_status; + ret = 0; + } + + /* Resume the thread so that it actually exits. Subsequent exit + events for LWPs that were deleted above will be ignored. */ + ptrace (PTRACE_CONT, lwpid, (PTRACE_TYPE_ARG3) 0, + (PTRACE_TYPE_ARG4) 0); + return ret; } + internal_error (__FILE__, __LINE__, + _("unknown ptrace event %d"), event); } /* Return the PC as read from the regcache of LWP, without any @@ -516,7 +579,7 @@ get_stop_pc (struct lwp_info *lwp) if (WSTOPSIG (lwp->last_status) == SIGTRAP && !lwp->stepping && !lwp->stopped_by_watchpoint - && lwp->last_status >> 16 == 0) + && !is_extended_waitstatus (lwp->last_status)) stop_pc -= the_low_target.decr_pc_after_break; if (debug_threads) @@ -1031,7 +1094,7 @@ get_detach_signal (struct thread_info *thread) } /* Extended wait statuses aren't real SIGTRAPs. */ - if (WSTOPSIG (status) == SIGTRAP && status >> 16 != 0) + if (WSTOPSIG (status) == SIGTRAP && is_extended_waitstatus (status)) { if (debug_threads) debug_printf ("GPS: lwp %s had stopped with extended " @@ -1716,11 +1779,13 @@ cancel_breakpoint (struct lwp_info *lwp) /* Do low-level handling of the event, and check if we should go on and pass it to caller code. Return the affected lwp if we are, or - NULL otherwise. */ + NULL otherwise. The wait status in WSTATP may be modified if an + exit event occurred. */ static struct lwp_info * -linux_low_filter_event (ptid_t filter_ptid, int lwpid, int wstat) +linux_low_filter_event (ptid_t filter_ptid, int lwpid, int *wstatp) { + int wstat = *wstatp; struct lwp_info *child; struct thread_info *thread; @@ -1772,7 +1837,7 @@ linux_low_filter_event (ptid_t filter_ptid, int lwpid, int wstat) architecture being defined already (so that CHILD has a valid regcache), and on LAST_STATUS being set (to check for SIGTRAP or not). */ - if (WIFSTOPPED (wstat)) + if (WIFSTOPPED (wstat) && !is_extended_exit (wstat)) { if (debug_threads && the_low_target.get_pc != NULL) @@ -1808,7 +1873,8 @@ linux_low_filter_event (ptid_t filter_ptid, int lwpid, int wstat) changes the debug registers meanwhile, we have the cached data we can rely on. */ - if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGTRAP) + if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGTRAP + && !is_extended_waitstatus (wstat)) { if (the_low_target.stopped_by_watchpoint == NULL) { @@ -1844,10 +1910,17 @@ linux_low_filter_event (ptid_t filter_ptid, int lwpid, int wstat) } if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGTRAP - && wstat >> 16 != 0) + && is_extended_waitstatus (wstat)) { - handle_extended_wait (child, wstat); - return NULL; + if (handle_extended_wait (child, &wstat)) + return NULL; + else + { + /* Update caller's wstat in case handle_extended_wait fixed + it up to reflect the actual status. */ + *wstatp = wstat; + return child; + } } if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGSTOP @@ -2067,7 +2140,7 @@ linux_wait_for_event_filtered (ptid_t wait_ptid, ptid_t filter_ptid, } event_child = linux_low_filter_event (filter_ptid, - ret, *wstatp); + ret, wstatp); if (event_child != NULL) { /* We got an event to report to the core. */