[PATCH v4] perf test: Fix test trace+probe_vfs_getname.sh on s390

[PATCH v4] perf test: Fix test trace+probe_vfs_getname.sh on s390

[Thomas Richter]

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 <tmricht@linux.ibm.com>
---
 tools/perf/tests/shell/lib/probe_vfs_getname.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/shell/lib/probe_vfs_getname.sh b/tools/perf/tests/shell/lib/probe_vfs_getname.sh
index 7cb99b433888..c2cc42daf924 100644
--- a/tools/perf/tests/shell/lib/probe_vfs_getname.sh
+++ b/tools/perf/tests/shell/lib/probe_vfs_getname.sh
@@ -14,7 +14,7 @@ add_probe_vfs_getname() {
 	if [ $had_vfs_getname -eq 1 ] ; then
 		line=$(perf probe -L getname_flags 2>&1 | egrep 'result.*=.*filename;' | sed -r 's/[[:space:]]+([[:digit:]]+)[[:space:]]+result->uptr.*/\1/')
 		perf probe -q       "vfs_getname=getname_flags:${line} pathname=result->name:string" || \
-		perf probe $verbose "vfs_getname=getname_flags:${line} pathname=filename:string"
+		perf probe $verbose "vfs_getname=getname_flags:${line} pathname=filename:ustring"
 	fi
 }
 
-- 
2.21.0

Re: [PATCH v4] perf test: Fix test trace+probe_vfs_getname.sh on s390

[Masami Hiramatsu]

On Mon, 17 Feb 2020 11:21:11 +0100
Thomas Richter <tmricht@linux.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@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 <tmricht@linux.ibm.com>

Looks good to me.

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you,

> ---
>  tools/perf/tests/shell/lib/probe_vfs_getname.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/shell/lib/probe_vfs_getname.sh b/tools/perf/tests/shell/lib/probe_vfs_getname.sh
> index 7cb99b433888..c2cc42daf924 100644
> --- a/tools/perf/tests/shell/lib/probe_vfs_getname.sh
> +++ b/tools/perf/tests/shell/lib/probe_vfs_getname.sh
> @@ -14,7 +14,7 @@ add_probe_vfs_getname() {
>  	if [ $had_vfs_getname -eq 1 ] ; then
>  		line=$(perf probe -L getname_flags 2>&1 | egrep 'result.*=.*filename;' | sed -r 's/[[:space:]]+([[:digit:]]+)[[:space:]]+result->uptr.*/\1/')
>  		perf probe -q       "vfs_getname=getname_flags:${line} pathname=result->name:string" || \
> -		perf probe $verbose "vfs_getname=getname_flags:${line} pathname=filename:string"
> +		perf probe $verbose "vfs_getname=getname_flags:${line} pathname=filename:ustring"
>  	fi
>  }
>  
> -- 
> 2.21.0
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>

Re: [PATCH v4] perf test: Fix test trace+probe_vfs_getname.sh on s390

[Arnaldo Carvalho de Melo]

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@linux.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@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 <tmricht@linux.ibm.com>
> 
> Looks good to me.
> 
> Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

Thanks, I tested it successfully on x86-64, applying.

- Arnaldo

[tip: perf/urgent] perf test: Fix test trace+probe_vfs_getname.sh on s390

[tip-bot2 for Thomas Richter]

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     2bbc83537614517730e9f2811195004b712de207
Gitweb:        https://git.kernel.org/tip/2bbc83537614517730e9f2811195004b712de207
Author:        Thomas Richter <tmricht@linux.ibm.com>
AuthorDate:    Mon, 17 Feb 2020 11:21:11 +01:00
Committer:     Arnaldo Carvalho de Melo <acme@redhat.com>
CommitterDate: Tue, 18 Feb 2020 10:13:28 -03:00

perf test: Fix test trace+probe_vfs_getname.sh on s390

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)

The 'filename' argument 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 the same. On some arches (ppc64 in
this case?) user address space is partially or completely the 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 space.

That is why I introduced the "ustring" type for kprobe events.

As far as I can see, Thomas's patch is sane. Thomas, could you show us
your result on your test environment?

Comments from Thomas Richter:

Test results for s/390 included above.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: http://lore.kernel.org/lkml/20200217102111.61137-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/tests/shell/lib/probe_vfs_getname.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/shell/lib/probe_vfs_getname.sh b/tools/perf/tests/shell/lib/probe_vfs_getname.sh
index 7cb99b4..c2cc42d 100644
--- a/tools/perf/tests/shell/lib/probe_vfs_getname.sh
+++ b/tools/perf/tests/shell/lib/probe_vfs_getname.sh
@@ -14,7 +14,7 @@ add_probe_vfs_getname() {
 	if [ $had_vfs_getname -eq 1 ] ; then
 		line=$(perf probe -L getname_flags 2>&1 | egrep 'result.*=.*filename;' | sed -r 's/[[:space:]]+([[:digit:]]+)[[:space:]]+result->uptr.*/\1/')
 		perf probe -q       "vfs_getname=getname_flags:${line} pathname=result->name:string" || \
-		perf probe $verbose "vfs_getname=getname_flags:${line} pathname=filename:string"
+		perf probe $verbose "vfs_getname=getname_flags:${line} pathname=filename:ustring"
 	fi
 }