Since we do not specify bash (and/or zsh) as a requirement, use the
standard error redirection that is more widely supported.

BEFORE:

 $ sudo perf test -v 62
 62: Check open filename arg using perf trace + vfs_getname:
 --- start ---
 test child forked, pid 27305
 ./tests/shell/trace+probe_vfs_getname.sh: 20: ./tests/shell/trace+probe_vfs_getname.sh: Syntax error: "&" unexpected
 test child finished with -2
 ---- end ----
 Check open filename arg using perf trace + vfs_getname: Skip

AFTER:

 $ sudo perf test -v 62
 64: Check open filename arg using perf trace + vfs_getname               :
 --- start ---
 test child forked, pid 23008
 Added new event:
   probe:vfs_getname    (on getname_flags:72 with pathname=result->name:string)

 You can now use it in all perf tools, such as:

         perf record -e probe:vfs_getname -aR sleep 1

      0.361 ( 0.008 ms): touch/23032 openat(dfd: CWD, filename: /tmp/temporary_file.VEh0n, flags: CREAT|NOCTTY|NONBLOCK|WRONLY, mode: IRUGO|IWUGO) = 4
 test child finished with 0
 ---- end ----
 Check open filename arg using perf trace + vfs_getname: Ok

Similar to commit 35435cd0, with the same title.
Signed-off-by: NKim Phillips <kim.phillips@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sandipan Das <sandipan@linux.vnet.ibm.com>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20180629124633.0a9f4bea54b8d2c28f265de2@arm.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Commit f231af78 ("perf test shell: Fix check open filename arg using
'perf trace' on s390x") added an exception for s390x to use openat()
instead of open() in the test that intercepts a open syscall to look for
the filename argument as obtained by the vfs_getname 'perf probe' it
puts in place at the getname_flags kernel function.

Its not just s390x that uses openat() instead of open(), so use 'perf
list' to look for the syscall:sys_enter_open(at)? present in the system
being tested instead of checking if the system is s390x.

In fact Namhyung pointed out that glibc 2.26 changed this behaviour, as
described in https://lwn.net/Articles/738694/, so systems where glibc is
>= 2.26 will need this patch for this test to work, which already took
place in some distros for architectures such as s390x, while Fedora 26
x86_64 is at glibc 2.25, i.e. still uses open().
Signed-off-by: NMichael Petlan <mpetlan@redhat.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Link: https://lkml.kernel.org/r/ab23fe42-1080-a46b-503e-744e097f414f@linux.vnet.ibm.com
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
LPU-Reference: 1275675985.12835754.1513095723265.JavaMail.zimbra@redhat.com
Link: https://lkml.kernel.org/n/tip-j2wbz9av1rw3thr3t0g4dtuk@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This 'perf test' case fails on s390x. The 'touch' command on s390x uses
the 'openat' system call to open the file named on the command line:

[root@s35lp76 perf]# perf probe -l
  probe:vfs_getname    (on getname_flags:72@fs/namei.c with pathname)
[root@s35lp76 perf]# perf trace -e open touch /tmp/abc
     0.400 ( 0.015 ms): touch/27542 open(filename:
		/usr/lib/locale/locale-archive, flags: CLOEXEC) = 3
[root@s35lp76 perf]#

There is no 'open' system call for file '/tmp/abc'. Instead the 'openat'
system call is used:

[root@s35lp76 perf]# strace touch /tmp/abc
    execve("/usr/bin/touch", ["touch", "/tmp/abc"], 0x3ffd547ec98
			/* 30 vars */) = 0
    [...]
    openat(AT_FDCWD, "/tmp/abc", O_WRONLY|O_CREAT|O_NOCTTY|O_NONBLOCK, 0666) = 3
    [...]

On s390x the 'egrep' command does not find a matching pattern and
returns an error.

Fix this for s390x create a platform dependent command line to enable
the 'perf probe' call to listen to the 'openat' system call and get the
expected output.
Signed-off-by: NThomas-Mich Richter <tmricht@linux.vnet.ibm.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>
LPU-Reference: 20171114071847.2381-1-tmricht@linux.vnet.ibm.com
Link: http://lkml.kernel.org/n/tip-3qf38jk0prz54rhmhyu871my@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This 'perf test' case fails on s390x. The 'touch' command on s390x uses
the 'openat' system call to open the file named on the command line:

[root@s35lp76 perf]# perf probe -l
  probe:vfs_getname    (on getname_flags:72@fs/namei.c with pathname)
[root@s35lp76 perf]# perf trace -e open touch /tmp/abc
     0.400 ( 0.015 ms): touch/27542 open(filename:
		/usr/lib/locale/locale-archive, flags: CLOEXEC) = 3
[root@s35lp76 perf]#

There is no 'open' system call for file '/tmp/abc'. Instead the 'openat'
system call is used:

[root@s35lp76 perf]# strace touch /tmp/abc
    execve("/usr/bin/touch", ["touch", "/tmp/abc"], 0x3ffd547ec98
			/* 30 vars */) = 0
    [...]
    openat(AT_FDCWD, "/tmp/abc", O_WRONLY|O_CREAT|O_NOCTTY|O_NONBLOCK, 0666) = 3
    [...]

On s390x the 'egrep' command does not find a matching pattern and
returns an error.

Fix this for s390x create a platform dependent command line to enable
the 'perf probe' call to listen to the 'openat' system call and get the
expected output.
Signed-off-by: NThomas-Mich Richter <tmricht@linux.vnet.ibm.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>
LPU-Reference: 20171114071847.2381-1-tmricht@linux.vnet.ibm.com
Link: http://lkml.kernel.org/n/tip-3qf38jk0prz54rhmhyu871my@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

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: NKim 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.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Uses the 'perf test shell' library to add probe:vfs_getname to the
system then use it with 'perf trace' using 'touch' to write to a temp
file, then checks that that was captured by the vfs_getname was used by
'perf trace', that already handles "probe:vfs_getname" if present, and
used in the "open" syscall "filename" argument beautifier.

Testing it:

  # perf test "trace + vfs_getname"
  61: Check open filename arg using perf trace + vfs_getname: Ok
  #

  # perf test -v "trace + vfs_getname"
  61: Check open filename arg using perf trace + vfs_getname:
  --- start ---
  test child forked, pid 30846
  Added new event:
    probe:vfs_getname    (on getname_flags:72 with pathname=result->name:string)

  You can now use it in all perf tools, such as:

  	perf record -e probe:vfs_getname -aR sleep 1

       2.237 ( 0.012 ms): touch/30855 open(filename: /tmp/temporary_file.kmoWQ, flags: CREAT|NOCTTY|NONBLOCK|WRONLY, mode: IRUGO|IWUGO) = 3
  test child finished with 0
  ---- end ----
  Check open filename arg using perf trace + vfs_getname: Ok
  #

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-j02nobfvvn9c7yrphdsnbqx0@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>