From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1510 invoked by alias); 24 May 2016 17:39:05 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 1501 invoked by uid 89); 24 May 2016 17:39:05 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.3 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=stopping, Stop X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Tue, 24 May 2016 17:38:55 +0000 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9F5EE8F4E2; Tue, 24 May 2016 17:38:53 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u4OHcp72012087; Tue, 24 May 2016 13:38:52 -0400 Subject: Re: [PATCH 7/8] Use reinsert_breakpoint for vCont;s To: Yao Qi , gdb-patches@sourceware.org References: <1463757161-25850-1-git-send-email-yao.qi@linaro.org> <1463757161-25850-8-git-send-email-yao.qi@linaro.org> From: Pedro Alves Message-ID: <1fe2e4c5-88c5-e7ec-4d8c-4ba6849ab7ba@redhat.com> Date: Tue, 24 May 2016 17:39:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 MIME-Version: 1.0 In-Reply-To: <1463757161-25850-8-git-send-email-yao.qi@linaro.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2016-05/txt/msg00432.txt.bz2 On 05/20/2016 04:12 PM, Yao Qi wrote: > This patch is to teach GDBserver using software single step to handle > vCont;s. Simply speaking, if the thread's resume request is resume_step, > install reinsert breakpoint at the next pcs when GDBserver is about to > resume threads. These reinsert breakpoints of a thread are removed, > when GDBserver gets an event from that thread. Note that GDBserver may > or may not report this event back to GDB. > > gdb/gdbserver: > > 2016-05-20 Yao Qi > > * linux-low.c (resume_stopped_resumed_lwps): If resume request > is resume_step, either set step to 1 or assert that reinsert > breakpoints are installed. > (linux_wait_1): Stop all threads, remove reinsert breakpoints, > and unstop them. > (linux_resume_one_thread): If resume request is resume_step, > either set step to 1 or assert that reinsert breakpoints are > installed. > (linux_resume): Install reinsert breakpoints if the thread is > requested to resume_step. > (proceed_one_lwp): If resume request is resume_step, > either set step to 1 or assert that reinsert breakpoints are > installed. > (proceed_all_lwps): Install reinsert breakpoints if the thread is > requested to resume_step. Spaces vs tabs, I think. > --- > gdb/gdbserver/linux-low.c | 125 ++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 121 insertions(+), 4 deletions(-) > > diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c > index d5f7097..22cf51a 100644 > --- a/gdb/gdbserver/linux-low.c > +++ b/gdb/gdbserver/linux-low.c > @@ -2526,7 +2526,18 @@ resume_stopped_resumed_lwps (struct inferior_list_entry *entry) > && !lp->status_pending_p > && thread->last_status.kind == TARGET_WAITKIND_IGNORE) > { > - int step = thread->last_resume_kind == resume_step; > + int step = 0; > + > + if (thread->last_resume_kind == resume_step) > + { ... > + if (can_hardware_single_step ()) > + step = 1; > + else > + { > + /* GDBserver must insert reinsert breakpoint for vCont;s. */ > + gdb_assert (has_reinsert_breakpoints (thread)); > + } This pattern seems to appear in many places in the series. Maybe we could add a function to wrap it? Something like: static int maybe_hw_step (struct thread_info *thread) { if (can_hardware_single_step ()) return 1; else { gdb_assert (has_reinsert_breakpoints (thread)); return 0; } } ? > + } > > if (debug_threads) > debug_printf ("RSRL: resuming stopped-resumed LWP %s at %s: step=%d\n", > @@ -3477,6 +3488,18 @@ linux_wait_1 (ptid_t ptid, > return ignore_event (ourstatus); > } > > + /* Remove reinsert breakpoints for resume_step. */ > + if (can_software_single_step () > + && current_thread->last_resume_kind == resume_step What if a vCont;t came in after the step had started and before it finished? Won't we have lost the resume_step linux_set_resume_request then? > + && has_reinsert_breakpoints (current_thread)) > + { > + stop_all_lwps (1, event_child); > + > + delete_reinsert_breakpoints (current_ptid); > + > + unstop_all_lwps (1, event_child); > + } > + > /* Note that all addresses are always "out of the step range" when > there's no range to begin with. */ > in_step_range = lwp_in_step_range (event_child); > @@ -4796,7 +4819,6 @@ linux_resume_one_thread (struct inferior_list_entry *entry, void *arg) > { > struct thread_info *thread = (struct thread_info *) entry; > struct lwp_info *lwp = get_thread_lwp (thread); > - int step; > int leave_all_stopped = * (int *) arg; > int leave_pending; > > @@ -4865,10 +4887,22 @@ linux_resume_one_thread (struct inferior_list_entry *entry, void *arg) > > if (!leave_pending) > { > + int step = 0; > + > if (debug_threads) > debug_printf ("resuming LWP %ld\n", lwpid_of (thread)); > > - step = (lwp->resume->kind == resume_step); > + if (lwp->resume->kind == resume_step) > + { > + if (can_hardware_single_step ()) > + step = 1; > + else > + { > + /* GDBserver must insert reinsert breakpoint for vCont;s. */ > + gdb_assert (has_reinsert_breakpoints (thread)); > + } > + } > + > linux_resume_one_lwp (lwp, step, lwp->resume->sig, NULL); > } > else > @@ -4909,6 +4943,7 @@ linux_resume (struct thread_resume *resume_info, size_t n) > struct thread_info *need_step_over = NULL; > int any_pending; > int leave_all_stopped; > + int resume_step_is_handled = 0; > > if (debug_threads) > { > @@ -4952,12 +4987,57 @@ linux_resume (struct thread_resume *resume_info, size_t n) > debug_printf ("Resuming, no pending status or step over needed\n"); > } > > + /* Before we resume the threads, if resume_step is requested by GDB, > + stop all threads and install reinsert breakpoints. */ > + if (!leave_all_stopped && can_software_single_step ()) > + { > + struct inferior_list_entry *inf, *tmp; > + > + if (debug_threads) > + debug_printf ("Handle resume_step.\n"); > + > + ALL_INFERIORS (&all_threads, inf, tmp) > + { > + struct thread_info *thread = (struct thread_info *) inf; > + struct lwp_info *lwp = get_thread_lwp (thread); > + > + if (lwp->resume != NULL && lwp->resume->kind == resume_step) > + { > + struct thread_info *saved_thread; > + > + if (!resume_step_is_handled) > + { > + stop_all_lwps (0, NULL); > + > + if (debug_threads) > + debug_printf ("Done stopping all threads.\n"); > + > + resume_step_is_handled = 1; > + } > + > + saved_thread = current_thread; > + current_thread = thread; > + install_software_single_step_breakpoints (lwp); > + current_thread = saved_thread; > + This current thread save/restore should move to install_software_single_step_breakpoints, as per the other patch. > + if (debug_threads) > + debug_printf ("Insert breakpoint for resume_step LWP %ld\n", > + lwpid_of (thread)); > + } > + } > + > + if (debug_threads) > + debug_printf ("Handle resume_step. Done\n"); > + } > + > /* Even if we're leaving threads stopped, queue all signals we'd > otherwise deliver. */ > find_inferior (&all_threads, linux_resume_one_thread, &leave_all_stopped); > > if (need_step_over) > start_step_over (get_thread_lwp (need_step_over)); > + else if (resume_step_is_handled) > + unstop_all_lwps (0, NULL); > > if (debug_threads) > { > @@ -5054,7 +5134,14 @@ proceed_one_lwp (struct inferior_list_entry *entry, void *except) > if (debug_threads) > debug_printf (" stepping LWP %ld, client wants it stepping\n", > lwpid_of (thread)); > - step = 1; > + > + if (can_hardware_single_step ()) > + step = 1; > + else > + { > + /* GDBserver must insert reinsert breakpoint for vCont;s. */ > + gdb_assert (has_reinsert_breakpoints (thread)); > + } > } > else if (lwp->bp_reinsert != 0) > { > @@ -5124,6 +5211,36 @@ proceed_all_lwps (void) > if (debug_threads) > debug_printf ("Proceeding, no step-over needed\n"); > > + /* Re-install the reinsert breakpoints on software single step target > + if the client wants it step. */ > + if (can_software_single_step ()) > + { > + struct inferior_list_entry *inf, *tmp; > + > + ALL_INFERIORS (&all_threads, inf, tmp) > + { > + struct thread_info *thread = (struct thread_info *) inf; > + > + if (thread->last_resume_kind == resume_step) > + { > + struct lwp_info *lwp = get_thread_lwp (thread); > + struct thread_info *saved_thread; > + > + saved_thread = current_thread; > + current_thread = thread; > + > + if (!has_reinsert_breakpoints (thread)) > + install_software_single_step_breakpoints (lwp); > + > + current_thread = saved_thread; Ditto. > + > + if (debug_threads) > + debug_printf ("Insert breakpoint for resume_step LWP %ld\n", > + lwpid_of (thread)); > + } > + } > + } > + > find_inferior (&all_threads, proceed_one_lwp, NULL); > } > > Thanks, Pedro Alves