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 <[email protected]>
---
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
On Mon, 17 Feb 2020 11:21:11 +0100
Thomas Richter <[email protected]> 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 <[email protected]>
Looks good to me.
Acked-by: Masami Hiramatsu <[email protected]>
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 <[email protected]>
Em Mon, Feb 17, 2020 at 09:10:10PM +0900, Masami Hiramatsu escreveu:
> On Mon, 17 Feb 2020 11:21:11 +0100
> Thomas Richter <[email protected]> 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 <[email protected]>
>
> Looks good to me.
>
> Acked-by: Masami Hiramatsu <[email protected]>
Thanks, I tested it successfully on x86-64, applying.
- Arnaldo
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 <[email protected]>
AuthorDate: Mon, 17 Feb 2020 11:21:11 +01:00
Committer: Arnaldo Carvalho de Melo <[email protected]>
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 <[email protected]>
Acked-by: Masami Hiramatsu <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Sumanth Korikkar <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
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
}