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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>
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Some kernels, like 4.19.13-300.fc29.x86_64 in fedora 29, fail with the
existing probe definition asking for the contents of result->name,
working when we ask for the 'filename' variable instead, so add a
fallback to that.
Now those tests are back working on fedora 29 systems with that kernel:
# perf test vfs_getname
65: Use vfs_getname probe to get syscall args filenames : Ok
66: Add vfs_getname probe to get syscall args filenames : Ok
67: Check open filename arg using perf trace + vfs_getname: Ok
#
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-klt3n0i58dfqttveti09q3fi@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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In some situations the vfs_getname is being added both as requested and
with a _1 suffix (inlines?):
probe:vfs_getname_1 (on getname_flags:63@acme/git/linux/fs/namei.c with pathname)
This ends up making the cleanup to miss that one, as it removes just
'probe:vfs_getname', which makes the second test to use this probe point
to fail, since it finds that leftover from the first test, use a
wildcard to remove both.
Before:
# perf test 60 61 62 63
60: Use vfs_getname probe to get syscall args filenames : FAILED!
61: probe libc's inet_pton & backtrace it with ping : Ok
62: Check open filename arg using perf trace + vfs_getname: FAILED!
63: Add vfs_getname probe to get syscall args filenames : Ok
After:
# perf test 60 61 62 63
60: Use vfs_getname probe to get syscall args filenames : Ok
61: probe libc's inet_pton & backtrace it with ping : Ok
62: Check open filename arg using perf trace + vfs_getname: Ok
63: Add vfs_getname probe to get syscall args filenames : Ok
#
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-2k5kutwr4ds36adiakyb4yvy@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Since we do not specify bash (and/or zsh) as a requirement, use the
standard error redirection that is more widely supported.
Signed-off-by: Kim Phillips <kim.phillips@arm.com>
Link: http://lkml.kernel.org/n/tip-ji5mhn3iilgch3eaay6csr6z@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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If that is the case, or if the required lib is not present, e.g.
elfutils-devel in Fedora systems, then just skip the tests requiring
DWARF analysis.
Before:
# rpm -e elfutils-devel
# perf test ping vfs_getname
60: Use vfs_getname probe to get syscall args filenames : FAILED!
61: probe libc's inet_pton & backtrace it with ping : Ok
62: Check open filename arg using perf trace + vfs_getname: FAILED!
63: Add vfs_getname probe to get syscall args filenames : FAILED!
#
After:
# perf test vfs_getname
60: Use vfs_getname probe to get syscall args filenames : Skip
62: Check open filename arg using perf trace + vfs_getname: Skip
63: Add vfs_getname probe to get syscall args filenames : Skip
#
Then, reinstalling elfutils-devel, rebuilding the tool and running
again:
# perf test vfs_getname
60: Use vfs_getname probe to get syscall args filenames : Ok
62: Check open filename arg using perf trace + vfs_getname: Ok
63: Add vfs_getname probe to get syscall args filenames : Ok
#
Reported-by: Kim Phillips <kim.phillips@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-d67tvn401fxrwr97pu5ihfb1@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Add a library function that checks if 'perf probe' is built into the
tool being tested, skipping tests that need it.
Testing it on a system after removing the library needed to build
'probe' as a perf subcommand:
# perf test ping vfs_getname
59: Use vfs_getname probe to get syscall args filenames : Skip
60: probe libc's inet_pton & backtrace it with ping : Skip
61: Check open filename arg using perf trace + vfs_getname: Skip
62: Add vfs_getname probe to get syscall args filenames : Skip
# perf probe
perf: 'probe' is not a perf-command. See 'perf --help'.
#
Now reinstalling elfutils-libelf-devel on this Fedora 26 system to
rebuild perf and then retest this:
# perf test ping vfs_getname
60: Use vfs_getname probe to get syscall args filenames : Ok
61: probe libc's inet_pton & backtrace it with ping : Ok
62: Check open filename arg using perf trace + vfs_getname: Ok
63: Add vfs_getname probe to get syscall args filenames : Ok
#
Reported-by: Kim Phillips <kim.phillips@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-ctdck2gzsskqhjzu3ebb62zm@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-3zxjswdbs2au3ih0rino0iy1@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Multiple tests will be able to reuse these functions, to test things
like perf report, 'trace', etc, using this probe.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-48xagvozhouhyi8fjota6o2d@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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