From patchwork Tue Dec 16 00:39:35 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Brobecker X-Patchwork-Id: 4270 Received: (qmail 1659 invoked by alias); 16 Dec 2014 00:39:40 -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 1649 invoked by uid 89); 16 Dec 2014 00:39:39 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.7 required=5.0 tests=AWL, BAYES_00 autolearn=ham version=3.3.2 X-HELO: rock.gnat.com Received: from rock.gnat.com (HELO rock.gnat.com) (205.232.38.15) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-SHA encrypted) ESMTPS; Tue, 16 Dec 2014 00:39:37 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by filtered-rock.gnat.com (Postfix) with ESMTP id C28971164F4; Mon, 15 Dec 2014 19:39:35 -0500 (EST) Received: from rock.gnat.com ([127.0.0.1]) by localhost (rock.gnat.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id hTLbgJJMdVLl; Mon, 15 Dec 2014 19:39:35 -0500 (EST) Received: from joel.gnat.com (localhost.localdomain [127.0.0.1]) by rock.gnat.com (Postfix) with ESMTP id A8C51116387; Mon, 15 Dec 2014 19:39:35 -0500 (EST) Received: by joel.gnat.com (Postfix, from userid 1000) id 5C0BF40166; Mon, 15 Dec 2014 19:39:35 -0500 (EST) Date: Mon, 15 Dec 2014 19:39:35 -0500 From: Joel Brobecker To: Pedro Alves Cc: gdb-patches@sourceware.org Subject: Re: [RFA/Linux] Ask kernel to kill inferior when GDB terminates Message-ID: <20141216003935.GH5457@adacore.com> References: <1415984034-27122-1-git-send-email-brobecker@adacore.com> <54663729.6010708@redhat.com> <20141114173255.GD5774@adacore.com> <20141119092547.GP5774@adacore.com> <546C69D4.5090300@redhat.com> <20141213162757.GL5457@adacore.com> <548EE088.20506@redhat.com> <20141215204323.GE5457@adacore.com> <548F4FFC.8060509@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <548F4FFC.8060509@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) > This makes it sound like "interruptible sleep" is some kind of wedged > state waiting for a debugger. But, this simply means your process is just > running as normal, and your test's case, normal means idling. Most likely, > your test program had a "sleep" call in it. IOW, it'd be in sleep state > even if had been started outside gdb. Another test program could go > to "T (stopped)", "R (running)", etc. You're right. Rev log updated. > This test must be called unconditionally. current_ptrace_options is > only initialized once: > > void > linux_enable_event_reporting (pid_t pid) > { > /* Check if we have initialized the ptrace features for this > target. If not, do it now. */ > if (current_ptrace_options == -1) > linux_check_ptrace_features (); > > so if the first process gdbserver debugs is an "attach" process, > but the second one is not, you'll miss setting PTRACE_O_EXITKILL on > the second process. > > Instead, always call linux_test_for_exitkill, and then in > linux_enable_event_reporting mask out PTRACE_O_EXITKILL > from current_ptrace_options if 'attached' is false. Right again. Here is an attached patch. Re-tested on x86_64-linux as previously done. gdb/ChangeLog: * nat/linux-ptrace.h (PTRACE_O_EXITKILL): Define if not already defined. (linux_enable_event_reporting): Add parameter "attached". * nat/linux-ptrace.c (linux_test_for_exitkill): New advance declaration. New function. (linux_check_ptrace_features): Add linux_test_for_exitkill call. (linux_enable_event_reporting): Add new parameter "attached". Do not call ptrace with the PTRACE_O_EXITKILL if ATTACHED is nonzero. * linux-nat.c (linux_init_ptrace): Add parameter "attached". Use it. Update function description. (linux_child_post_attach, linux_child_post_startup_inferior): Update call to linux_enable_event_reporting. gdb/gdbserver/ChangeLog: * linux-low.c (linux_low_filter_event): Update call to linux_enable_event_reporting following the addition of a new parameter to that function. Thanks, Pedro. From 4ad92cbfc3dfdfffe46f20e2b6e8df7a793c9ea7 Mon Sep 17 00:00:00 2001 From: Joel Brobecker Date: Tue, 11 Nov 2014 10:07:21 +0400 Subject: [PATCH] [Linux] Ask kernel to kill inferior when GDB terminates This patch enhances GDB on GNU/Linux systems in the situation where we are debugging an inferior that was created from GDB (as opposed to attached to), by asking the kernel to kill the inferior if GDB terminates without doing it itself. This would typically happen when GDB encounters a problem and crashes, or when it gets killed by an external process. This can be observed by starting a program under GDB, and then killing GDB with signal 9. After GDB is killed, the inferior still remains. This patch also fixes GDBserver similarly. This fix is conditional on the kernel supporting the PTRACE_O_EXITKILL feature. On older kernels, the behavior remains unchanged. gdb/ChangeLog: * nat/linux-ptrace.h (PTRACE_O_EXITKILL): Define if not already defined. (linux_enable_event_reporting): Add parameter "attached". * nat/linux-ptrace.c (linux_test_for_exitkill): New advance declaration. New function. (linux_check_ptrace_features): Add linux_test_for_exitkill call. (linux_enable_event_reporting): Add new parameter "attached". Do not call ptrace with the PTRACE_O_EXITKILL if ATTACHED is nonzero. * linux-nat.c (linux_init_ptrace): Add parameter "attached". Use it. Update function description. (linux_child_post_attach, linux_child_post_startup_inferior): Update call to linux_enable_event_reporting. gdb/gdbserver/ChangeLog: * linux-low.c (linux_low_filter_event): Update call to linux_enable_event_reporting following the addition of a new parameter to that function. Tested on x86_64-linux, native and native-gdbserver. I also verified by hand that the inferior gets killed when killing GDB in the "run" case, while the inferior remains in the "attach" case. Same for GDBserver. --- gdb/gdbserver/linux-low.c | 4 +++- gdb/linux-nat.c | 12 +++++++----- gdb/nat/linux-ptrace.c | 34 +++++++++++++++++++++++++++++++--- gdb/nat/linux-ptrace.h | 7 ++++++- 4 files changed, 47 insertions(+), 10 deletions(-) diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c index 5ea9200..65f72a2 100644 --- a/gdb/gdbserver/linux-low.c +++ b/gdb/gdbserver/linux-low.c @@ -1878,7 +1878,9 @@ linux_low_filter_event (ptid_t filter_ptid, int lwpid, int wstat) if (WIFSTOPPED (wstat) && child->must_set_ptrace_flags) { - linux_enable_event_reporting (lwpid); + struct process_info *proc = find_process_pid (pid_of (thread)); + + linux_enable_event_reporting (lwpid, proc->attached); child->must_set_ptrace_flags = 0; } diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c index 29133f9..845d566 100644 --- a/gdb/linux-nat.c +++ b/gdb/linux-nat.c @@ -321,25 +321,27 @@ pull_pid_from_list (struct simple_pid_list **listp, int pid, int *statusp) } /* Initialize ptrace warnings and check for supported ptrace - features given PID. */ + features given PID. + + ATTACHED should be nonzero iff we attached to the inferior. */ static void -linux_init_ptrace (pid_t pid) +linux_init_ptrace (pid_t pid, int attached) { - linux_enable_event_reporting (pid); + linux_enable_event_reporting (pid, attached); linux_ptrace_init_warnings (); } static void linux_child_post_attach (struct target_ops *self, int pid) { - linux_init_ptrace (pid); + linux_init_ptrace (pid, 1); } static void linux_child_post_startup_inferior (struct target_ops *self, ptid_t ptid) { - linux_init_ptrace (ptid_get_pid (ptid)); + linux_init_ptrace (ptid_get_pid (ptid), 0); } /* Return the number of known LWPs in the tgid given by PID. */ diff --git a/gdb/nat/linux-ptrace.c b/gdb/nat/linux-ptrace.c index 8bc3f16..a0e0c32 100644 --- a/gdb/nat/linux-ptrace.c +++ b/gdb/nat/linux-ptrace.c @@ -307,6 +307,7 @@ linux_child_function (gdb_byte *child_stack) static void linux_test_for_tracesysgood (int child_pid); static void linux_test_for_tracefork (int child_pid); +static void linux_test_for_exitkill (int child_pid); /* Determine ptrace features available on this target. */ @@ -338,6 +339,8 @@ linux_check_ptrace_features (void) linux_test_for_tracefork (child_pid); + linux_test_for_exitkill (child_pid); + /* Clean things up and kill any pending children. */ do { @@ -449,19 +452,44 @@ linux_test_for_tracefork (int child_pid) "(%d, status 0x%x)"), ret, status); } -/* Enable reporting of all currently supported ptrace events. */ +/* Determine if PTRACE_O_EXITKILL can be used. */ + +static void +linux_test_for_exitkill (int child_pid) +{ + int ret; + + ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0, + (PTRACE_TYPE_ARG4) PTRACE_O_EXITKILL); + + if (ret == 0) + current_ptrace_options |= PTRACE_O_EXITKILL; +} + +/* Enable reporting of all currently supported ptrace events. + ATTACHED should be nonzero if we have attached to the inferior. */ void -linux_enable_event_reporting (pid_t pid) +linux_enable_event_reporting (pid_t pid, int attached) { + int ptrace_options; + /* Check if we have initialized the ptrace features for this target. If not, do it now. */ if (current_ptrace_options == -1) linux_check_ptrace_features (); + ptrace_options = current_ptrace_options; + if (attached) + { + /* When attached to our inferior, we do not want the inferior + to die with us if we terminate unexpectedly. */ + ptrace_options &= ~PTRACE_O_EXITKILL; + } + /* Set the options. */ ptrace (PTRACE_SETOPTIONS, pid, (PTRACE_TYPE_ARG3) 0, - (PTRACE_TYPE_ARG4) (uintptr_t) current_ptrace_options); + (PTRACE_TYPE_ARG4) (uintptr_t) ptrace_options); } /* Disable reporting of all currently supported ptrace events. */ diff --git a/gdb/nat/linux-ptrace.h b/gdb/nat/linux-ptrace.h index 31a77cd..588d38a 100644 --- a/gdb/nat/linux-ptrace.h +++ b/gdb/nat/linux-ptrace.h @@ -69,6 +69,11 @@ struct buffer; #endif /* PTRACE_EVENT_FORK */ +#ifndef PTRACE_O_EXITKILL +/* Only defined in Linux Kernel 3.8 or later. */ +#define PTRACE_O_EXITKILL 0x00100000 +#endif + #if (defined __bfin__ || defined __frv__ || defined __sh__) \ && !defined PTRACE_GETFDPIC #define PTRACE_GETFDPIC 31 @@ -85,7 +90,7 @@ struct buffer; extern void linux_ptrace_attach_fail_reason (pid_t pid, struct buffer *buffer); extern void linux_ptrace_init_warnings (void); -extern void linux_enable_event_reporting (pid_t pid); +extern void linux_enable_event_reporting (pid_t pid, int attached); extern void linux_disable_event_reporting (pid_t pid); extern int linux_supports_tracefork (void); extern int linux_supports_traceclone (void); -- 1.9.1