From patchwork Tue May 27 17:01:10 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Don Breazeal X-Patchwork-Id: 1172 Received: (qmail 2431 invoked by alias); 27 May 2014 17:01:17 -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 2368 invoked by uid 89); 27 May 2014 17:01:17 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-0.7 required=5.0 tests=AWL, BAYES_00, UNSUBSCRIBE_BODY autolearn=no 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; Tue, 27 May 2014 17:01:15 +0000 Received: from svr-orw-exc-10.mgc.mentorg.com ([147.34.98.58]) by relay1.mentorg.com with esmtp id 1WpKkR-0007kQ-FG from donb@codesourcery.com for gdb-patches@sourceware.org; Tue, 27 May 2014 10:01:11 -0700 Received: from [127.0.0.1] ([172.30.2.61]) by SVR-ORW-EXC-10.mgc.mentorg.com with Microsoft SMTPSVC(6.0.3790.4675); Tue, 27 May 2014 10:01:10 -0700 Message-ID: <5384C4D6.8090608@codesourcery.com> Date: Tue, 27 May 2014 10:01:10 -0700 From: "Breazeal, Don" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Yao Qi , gdb-patches@sourceware.org Subject: Re: [PATCH] Fix for gdb/PR 14808, vfork/exec inferior problem References: <1400186622-3321-1-git-send-email-donb@codesourcery.com> <537FEE77.4060509@codesourcery.com> In-Reply-To: <537FEE77.4060509@codesourcery.com> X-IsSubscribed: yes On 5/23/2014 5:57 PM, Yao Qi wrote: > A nit on changelog entry: > > On 05/16/2014 04:43 AM, Don Breazeal wrote: >> gdb/ >> 2014-05-15 Don Breazeal >> > PR gdb/14808 >> * infrun.c (handle_vfork_child_exec_or_exit): For the case >> of a vfork where we follow the child and detach the parent, >> and the child execs, create a new pspace for the parent >> inferior. > > With this, the magic script can connect this commit to the right PR. > > The patch looks good to me, but I can't approve it. > Thanks for checking this. An updated ChangeLog and (unchanged) patch follow. --Don gdb/ 2014-05-12 Don Breazeal PR gdb/14808 * infrun.c (handle_vfork_child_exec_or_exit): For the case of a vfork where we follow the child and detach the parent, and the child execs, create a new pspace and aspace for the parent inferior. gdb/testsuite 2014-05-12 Don Breazeal * gdb.base/foll-vfork.exp (vfork_relations_in_info_inferiors): Test that after a vfork and child exec, the parent's exec file name has not been changed. --- gdb/infrun.c | 42 ++++++++++++++++++++++----------- gdb/testsuite/gdb.base/foll-vfork.exp | 11 ++++++++ 2 files changed, 39 insertions(+), 14 deletions(-) diff --git a/gdb/infrun.c b/gdb/infrun.c index ab39b6e..82a67d5 100644 --- a/gdb/infrun.c +++ b/gdb/infrun.c @@ -649,6 +649,7 @@ handle_vfork_child_exec_or_exit (int exec) struct cleanup *old_chain; struct program_space *pspace; struct address_space *aspace; + struct inferior *parent_inf; /* follow-fork child, detach-on-fork on. */ @@ -665,27 +666,39 @@ handle_vfork_child_exec_or_exit (int exec) else old_chain = save_current_space_and_thread (); - /* We're letting loose of the parent. */ + /* Make the parent the current inferior for target_detach. */ tp = any_live_thread_of_process (inf->vfork_parent->pid); switch_to_thread (tp->ptid); - /* We're about to detach from the parent, which implicitly - removes breakpoints from its address space. There's a - catch here: we want to reuse the spaces for the child, - but, parent/child are still sharing the pspace at this - point, although the exec in reality makes the kernel give - the child a fresh set of new pages. The problem here is - that the breakpoints module being unaware of this, would - likely chose the child process to write to the parent - address space. Swapping the child temporarily away from - the spaces has the desired effect. Yes, this is "sort - of" a hack. */ - + /* The child inferior INF may be dead, so avoid giving the + breakpoints module the option to write through to it + by swapping the child temporarily away from the spaces + (cloning a program space resets breakpoints). */ pspace = inf->pspace; aspace = inf->aspace; inf->aspace = NULL; inf->pspace = NULL; + if (exec) + { + /* The parent and child inferiors have been sharing + program and address space structures from the point + where the parent called vfork. Now that the child has + called exec and we are detaching from the parent, the + parent inferior needs to have its own pspace and aspace + so that changes in the child don't affect it. We have + to give the new spaces to the parent since we saved the + child's spaces as the current spaces above. Even though + we are detaching the parent, we want to keep the + corresponding entry in the inferiors list intact. */ + parent_inf = current_inferior (); + parent_inf->aspace = new_address_space (); + parent_inf->pspace = add_program_space (parent_inf->aspace); + parent_inf->removable = inf->removable; + set_current_program_space (parent_inf->pspace); + clone_program_space (parent_inf->pspace, pspace); + } + if (debug_infrun || info_verbose) { target_terminal_ours (); @@ -702,9 +715,10 @@ handle_vfork_child_exec_or_exit (int exec) inf->vfork_parent->pid); } + /* Detach the parent. */ target_detach (NULL, 0); - /* Put it back. */ + /* Put the child spaces back. */ inf->pspace = pspace; inf->aspace = aspace; diff --git a/gdb/testsuite/gdb.base/foll-vfork.exp b/gdb/testsuite/gdb.base/foll-vfork.exp index fe3663c..e9b0110 100644 --- a/gdb/testsuite/gdb.base/foll-vfork.exp +++ b/gdb/testsuite/gdb.base/foll-vfork.exp @@ -442,6 +442,17 @@ proc vfork_relations_in_info_inferiors { variant } { pass $test } } + + # Make sure the exec file name of the vfork parent is not + # changed when the child's is changed. + if { $variant == "exec" } { + set test "exec file name change" + gdb_test_multiple "info inferiors" $test { + -re " 2 .*vforked-prog.* 1 .*foll-vfork.*$gdb_prompt " { + pass $test + } + } + } }} proc do_vfork_and_follow_parent_tests {} {