From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnaldo Carvalho de Melo Subject: Re: [PATCH v4] perf test: Fix test trace+probe_vfs_getname.sh on s390 Date: Mon, 17 Feb 2020 11:29:35 -0300 Message-ID: <20200217142935.GA19953@kernel.org> References: <20200217102111.61137-1-tmricht@linux.ibm.com> <20200217211010.fa9c643c517c110abaa5b554@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20200217211010.fa9c643c517c110abaa5b554@kernel.org> Sender: linux-kernel-owner@vger.kernel.org To: Masami Hiramatsu Cc: Thomas Richter , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, gor@linux.ibm.com, sumanthk@linux.ibm.com, heiko.carstens@de.ibm.com List-Id: linux-perf-users.vger.kernel.org Em Mon, Feb 17, 2020 at 09:10:10PM +0900, Masami Hiramatsu escreveu: > On Mon, 17 Feb 2020 11:21:11 +0100 > Thomas Richter wrote: > > > This test places a kprobe to function getname_flags() in the kernel > > which has the following prototype: > > > > struct filename * > > getname_flags(const char __user *filename, int flags, int *empty) > > > > Variable filename points to a filename located in user space memory. > > Looking at > > commit 88903c464321c ("tracing/probe: Add ustring type for user-space string") > > the kprobe should indicate that user space memory is accessed. > > > > Output before: > > [root@m35lp76 perf]# ./perf test 66 67 > > 66: Use vfs_getname probe to get syscall args filenames : FAILED! > > 67: Check open filename arg using perf trace + vfs_getname: FAILED! > > [root@m35lp76 perf]# > > > > Output after: > > [root@m35lp76 perf]# ./perf test 66 67 > > 66: Use vfs_getname probe to get syscall args filenames : Ok > > 67: Check open filename arg using perf trace + vfs_getname: Ok > > [root@m35lp76 perf]# > > > > Comments from Masami Hiramatsu: > > This bug doesn't happen on x86 or other archs on which user-address > > space and kernel address space is same. On some arch (ppc64 in this case?) > > user-address space is partially or completely same as kernel address space. > > (Yes, they switch the world when running into the kernel) In this case, > > we need to use different data access functions for each spaces. > > That is why I introduced "ustring" type for kprobe event. > > As far as I can see, Thomas's patch is sane. Thomas, could you show us > > your result on your test environment? > > Thank you > > > > Comments from Thomas Richter: > > Test results included above. > > > > Signed-off-by: Thomas Richter > > Looks good to me. > > Acked-by: Masami Hiramatsu Thanks, I tested it successfully on x86-64, applying. - Arnaldo