From patchwork Fri May 30 15:57:42 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pedro Alves X-Patchwork-Id: 1208 Received: (qmail 2186 invoked by alias); 30 May 2014 15:57:49 -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 2172 invoked by uid 89); 30 May 2014 15:57:48 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.2 required=5.0 tests=AWL, BAYES_00, RP_MATCHES_RCVD, SPF_HELO_PASS, SPF_PASS autolearn=ham version=3.3.2 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 ESMTP; Fri, 30 May 2014 15:57:47 +0000 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s4UFviNJ019800 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 30 May 2014 11:57:44 -0400 Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id s4UFvgsQ021755; Fri, 30 May 2014 11:57:43 -0400 Message-ID: <5388AA76.4070101@redhat.com> Date: Fri, 30 May 2014 16:57:42 +0100 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Joel Brobecker CC: gdb-patches@sourceware.org Subject: Re: [RFA/7.8] user breakpoint not inserted if software-single-step at same location References: <1401394280-14999-1-git-send-email-brobecker@adacore.com> <5387BFF0.6010208@redhat.com> <20140530122253.GC4289@adacore.com> <53887ED5.5050603@redhat.com> <20140530132659.GD4289@adacore.com> In-Reply-To: <20140530132659.GD4289@adacore.com> On 05/30/2014 02:26 PM, Joel Brobecker wrote: >>>> - if there's still a non-sss breakpoint inserted at the >>>> same address, then don't actually remove the breakpoint >>>> off of the target, just wipe it from gdb's list. >>> >>> It seems to me that we'd need to merge your initial recommendation >>> into your summary above, right? >> >> I admit I don't know what recommendation you're referring to. :-) > > Sorry! This one: > > | but we'll need to create/clone the location and its shadow buffer, > | and then still handle the issue in the "remove" path. Ah. Yes. > I am wondering how to create that test, because it would be > a little tricky. We need to set ourselves into a situation > where we single-step out of a breakpoint with the second SSS > breakpoint being at the same address as one of the user breakpoints, > that second SSS not being the one that gets hit during that > first single-step-out-of-breakpoint. Yeah. Hmmm. *thinks* I have a very simple idea, around "jump" + "always-inserted". E.g., with, where b+ indicates a user breakpoint: 00001 nop <- PC b+ 00002 nop - enable breakpoints always inserted mode - step to 00002 - gdb removes the sss breakpoint. - due to always inserted mode, gdb does not remove b+, but due to the bug, it's actually no longer planted. - the b+ breakpoint should be reported to the user. - now do "jump $pc". - expected: The breakpoint should trigger immediately again. - what we get on sss targets: GDB loses control, and program runs to end. Ah, I just went ahead and tried that against my by sss-on-x86 branch, and indeed it fails here, while it passes on pristine mainline / hardware stepping. 8<---------- From e13bf4d64bf299111193a1f27a0bbc194d9b34f4 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Fri, 30 May 2014 16:52:36 +0100 Subject: [PATCH] test for sss breakpoints bug --- gdb/testsuite/gdb.base/sss-bp-on-user-bp.c | 30 ++++++++++++++++ gdb/testsuite/gdb.base/sss-bp-on-user-bp.exp | 51 ++++++++++++++++++++++++++++ 2 files changed, 81 insertions(+) create mode 100644 gdb/testsuite/gdb.base/sss-bp-on-user-bp.c create mode 100644 gdb/testsuite/gdb.base/sss-bp-on-user-bp.exp diff --git a/gdb/testsuite/gdb.base/sss-bp-on-user-bp.c b/gdb/testsuite/gdb.base/sss-bp-on-user-bp.c new file mode 100644 index 0000000..ff82051 --- /dev/null +++ b/gdb/testsuite/gdb.base/sss-bp-on-user-bp.c @@ -0,0 +1,30 @@ +/* This testcase is part of GDB, the GNU debugger. + + Copyright 2014 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include +#include + +int +main (void) +{ + /* Assume writes to integers compile to a single instruction. */ + volatile int i = 0; + + i = 1; /* set foo break here */ + i = 2; /* set bar break here */ + return 0; +} diff --git a/gdb/testsuite/gdb.base/sss-bp-on-user-bp.exp b/gdb/testsuite/gdb.base/sss-bp-on-user-bp.exp new file mode 100644 index 0000000..bb63d3f --- /dev/null +++ b/gdb/testsuite/gdb.base/sss-bp-on-user-bp.exp @@ -0,0 +1,51 @@ +# Copyright 2014 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +# Test that removing a single-step breakpoint that is placed at the +# same address as another regular breakpoint leaves the regular +# breakpoint inserted. + +standard_testfile +set executable ${testfile} + +if {[prepare_for_testing "failed to prepare" $testfile $srcfile debug]} { + return -1 +} + +if ![runto_main] then { + fail "Can't run to main" + return 0 +} + +gdb_breakpoint [gdb_get_line_number "set foo break here"] +gdb_continue_to_breakpoint "first breakpoint" ".* set foo break here .*" + +gdb_breakpoint [gdb_get_line_number "set bar break here"] + +# So that GDB doesn't try to remove the regular breakpoint when the +# step finishes. +gdb_test_no_output "set breakpoint always-inserted on" + +# On software single-step targets, this step will want to momentarily +# place a single-step breakpoint over the bar breakpoint, and then +# remove it. But, a regular breakpoint it planted there already, and +# with always-inserted on, should remain planted when the step +# finishes. +gdb_test "si" "Breakpoint .* bar break .*" + +# If the breakpoint is still correctly inserted, then this jump should +# re-trigger it. Otherwise, GDB will lose control and the program +# will exit. +gdb_test "jump *\$pc" "Breakpoint .* bar break .*"