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Date: Mon, 17 Feb 2020 11:29:35 -0300 From: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com> To: Masami Hiramatsu <mhiramat@...nel.org> Cc: Thomas Richter <tmricht@...ux.ibm.com>, linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org, gor@...ux.ibm.com, sumanthk@...ux.ibm.com, heiko.carstens@...ibm.com Subject: Re: [PATCH v4] perf test: Fix test trace+probe_vfs_getname.sh on s390 Em Mon, Feb 17, 2020 at 09:10:10PM +0900, Masami Hiramatsu escreveu: > On Mon, 17 Feb 2020 11:21:11 +0100 > Thomas Richter <tmricht@...ux.ibm.com> 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@...lp76 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@...lp76 perf]# > > > > Output after: > > [root@...lp76 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@...lp76 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 <tmricht@...ux.ibm.com> > > Looks good to me. > > Acked-by: Masami Hiramatsu <mhiramat@...nel.org> Thanks, I tested it successfully on x86-64, applying. - Arnaldo
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