In Makefile.config, to make all libraries flags have _SUPPORT suffix,
rename HAVE_DWARF_GETLOCATIONS to HAVE_DWARF_GETLOCATIONS_SUPPORT
Signed-off-by: NJin Yao <yao.jin@linux.intel.com>
Suggested-by: NIngo Molnar <mingo@kernel.org>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1522402036-22915-4-git-send-email-yao.jin@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

For most of libraries, in perf.config, they are recorded with -DHAVE_XXX in
CFLAGS according to if the libraries are compiled-in.  Then C code then will
know if the library is compiled-in or not.

While for glibc, no -DHAVE_GLIBC_SUPPORT exists.

For python and perl libraries, only -DNO_PYTHON and -DNO_LIBPERL exist.

To make the code more consistent, the patch creates -DHAVE_LIBPYTHON_SUPPORT
and -DHAVE_LIBPERL_SUPPORT if the python and perl libraries are compiled-in.

Since the existing flags -DNO_PYTHON and -DNO_LIBPERL are being used in many
places in C code, this patch doesn't remove them. In a follow-up patch, we will
recontruct the C code and then use HAVE_XXX instead.

v3:

Move 'CFLAGS += -DHAVE_LIBPYTHON_SUPPORT' and 'CFLAGS +=
-DHAVE_LIBPERL_SUPPORT' to other places to avoid duplicated feature checking.

v2:

Create -DHAVE_GLIBC_SUPPORT, -DHAVE_LIBPYTHON_SUPPORT and
-DHAVE_LIBPERL_SUPPORT.
Signed-off-by: NJin Yao <yao.jin@linux.intel.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1522402036-22915-3-git-send-email-yao.jin@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Based on prior work:

  https://lkml.org/lkml/2014/5/6/395

and on how other arches add libdw unwind support.  Includes support for
running the unwind test, e.g., on a system with only elfutils' libdw
0.170, the test now runs, and successfully:

  $ ./perf test unwind
  56: Test dwarf unwind                 : Ok
Originally-by: NJean Pihet <jean.pihet@linaro.org>
Reported-by: NChristian Hansen <chansen3@cisco.com>
Signed-off-by: NKim Phillips <kim.phillips@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180308211030.4ee4a0d6ff6dc5cda1b567d4@arm.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Added Python 3 support while keeping Python 2.7 compatibility.

Committer notes:

This doesn't make it to auto detect python 3, one has to explicitely ask
it to build with python 3 devel files, here are the instructions
provided by Jaroslav:

 ---
  $ cp -a tools/perf tools/python3-perf
  $ make V=1 prefix=/usr -C tools/perf PYTHON=/usr/bin/python2 all
  $ make V=1 prefix=/usr -C tools/python3-perf PYTHON=/usr/bin/python3 all
  $ make V=1 prefix=/usr -C tools/python3-perf PYTHON=/usr/bin/python3 DESTDIR=%{buildroot} install-python_ext
  $ make V=1 prefix=/usr -C tools/perf PYTHON=/usr/bin/python2 DESTDIR=%{buildroot} install-python_ext
 ---

We need to make this automatic, just like the existing tests for checking if
the python2 devel files are in place, allowing the build with python3 if
available, fallbacking to python2 and then just disabling it if none are
available.

So, using the PYTHON variable to build it using O= we get:

Before this patch:

  $ rpm -q python3 python3-devel
  python3-3.6.4-7.fc27.x86_64
  python3-devel-3.6.4-7.fc27.x86_64
  $ rm -rf /tmp/build/perf/ ; mkdir -p /tmp/build/perf ; make O=/tmp/build/perf PYTHON=/usr/bin/python3 -C tools/perf install-bin
  make: Entering directory '/home/acme/git/linux/tools/perf'
  <SNIP>
  Makefile.config:670: Python 3 is not yet supported; please set
  Makefile.config:671: PYTHON and/or PYTHON_CONFIG appropriately.
  Makefile.config:672: If you also have Python 2 installed, then
  Makefile.config:673: try something like:
  Makefile.config:674:
  Makefile.config:675:   make PYTHON=python2
  Makefile.config:676:
  Makefile.config:677: Otherwise, disable Python support entirely:
  Makefile.config:678:
  Makefile.config:679:   make NO_LIBPYTHON=1
  Makefile.config:680:
  Makefile.config:681: *** .  Stop.
  make[1]: *** [Makefile.perf:212: sub-make] Error 2
  make: *** [Makefile:110: install-bin] Error 2
  make: Leaving directory '/home/acme/git/linux/tools/perf'
  $

After:

  $ make O=/tmp/build/perf PYTHON=python3 -C tools/perf install-bin
  $ ldd ~/bin/perf | grep python
	libpython3.6m.so.1.0 => /lib64/libpython3.6m.so.1.0 (0x00007f58a31e8000)
  $ rpm -qf /lib64/libpython3.6m.so.1.0
  python3-libs-3.6.4-7.fc27.x86_64
  $

Now verify that when using the binding the right ELF file is loaded,
using perf trace:

  $ perf trace -e open* perf test python
     0.051 ( 0.016 ms): perf/3927 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC           ) = 3
<SNIP>
  18: 'import perf' in python                               :
     8.849 ( 0.013 ms): sh/3929 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC           ) = 3
<SNIP>
    25.572 ( 0.008 ms): python3/3931 openat(dfd: CWD, filename: /tmp/build/perf/python/perf.cpython-36m-x86_64-linux-gnu.so, flags: CLOEXEC) = 3
<SNIP>
 Ok
<SNIP>
  $

And using tools/perf/python/twatch.py, to show PERF_RECORD_ metaevents:

  $ python3 tools/perf/python/twatch.py
  cpu: 3, pid: 16060, tid: 16060 { type: fork, pid: 5207, ppid: 16060, tid: 5207, ptid: 16060, time: 10798513015459}
  cpu: 3, pid: 16060, tid: 16060 { type: fork, pid: 5208, ppid: 16060, tid: 5208, ptid: 16060, time: 10798513562503}
  cpu: 0, pid: 5208, tid: 5208 { type: comm, pid: 5208, tid: 5208, comm: grep }
  cpu: 2, pid: 5207, tid: 5207 { type: comm, pid: 5207, tid: 5207, comm: ps }
  cpu: 2, pid: 5207, tid: 5207 { type: exit, pid: 5207, ppid: 5207, tid: 5207, ptid: 5207, time: 10798551337484}
  cpu: 3, pid: 5208, tid: 5208 { type: exit, pid: 5208, ppid: 5208, tid: 5208, ptid: 5208, time: 10798551292153}
  cpu: 3, pid: 601, tid: 601 { type: fork, pid: 5209, ppid: 601, tid: 5209, ptid: 601, time: 10801779977324}
  ^CTraceback (most recent call last):
    File "tools/perf/python/twatch.py", line 68, in <module>
      main()
    File "tools/perf/python/twatch.py", line 40, in main
      evlist.poll(timeout = -1)
  KeyboardInterrupt
  $

  # ps ax|grep twatch
 5197 pts/8    S+     0:00 python3 tools/perf/python/twatch.py
  # ls -la /proc/5197/smaps
  -r--r--r--. 1 acme acme 0 Feb 19 13:14 /proc/5197/smaps
  # grep python /proc/5197/smaps
  558111307000-558111309000 r-xp 00000000 fd:00 3151710  /usr/bin/python3.6
  558111508000-558111509000 r--p 00001000 fd:00 3151710  /usr/bin/python3.6
  558111509000-55811150a000 rw-p 00002000 fd:00 3151710  /usr/bin/python3.6
  7ffad6fc1000-7ffad7008000 r-xp 00000000 00:2d 220196   /tmp/build/perf/python/perf.cpython-36m-x86_64-linux-gnu.so
  7ffad7008000-7ffad7207000 ---p 00047000 00:2d 220196   /tmp/build/perf/python/perf.cpython-36m-x86_64-linux-gnu.so
  7ffad7207000-7ffad7208000 r--p 00046000 00:2d 220196   /tmp/build/perf/python/perf.cpython-36m-x86_64-linux-gnu.so
  7ffad7208000-7ffad7215000 rw-p 00047000 00:2d 220196   /tmp/build/perf/python/perf.cpython-36m-x86_64-linux-gnu.so
  7ffadea77000-7ffaded3d000 r-xp 00000000 fd:00 3151795  /usr/lib64/libpython3.6m.so.1.0
  7ffaded3d000-7ffadef3c000 ---p 002c6000 fd:00 3151795  /usr/lib64/libpython3.6m.so.1.0
  7ffadef3c000-7ffadef42000 r--p 002c5000 fd:00 3151795  /usr/lib64/libpython3.6m.so.1.0
  7ffadef42000-7ffadefa5000 rw-p 002cb000 fd:00 3151795  /usr/lib64/libpython3.6m.so.1.0
  #

And with this patch, but building normally, without specifying the
PYTHON=python3 part, which will make it use python2 if its devel files are
available, like in this test:

  $ make O=/tmp/build/perf -C tools/perf install-bin
  $ ldd ~/bin/perf | grep python
	libpython2.7.so.1.0 => /lib64/libpython2.7.so.1.0 (0x00007f6a44410000)
  $ ldd /tmp/build/perf/python_ext_build/lib/perf.so  | grep python
	libpython2.7.so.1.0 => /lib64/libpython2.7.so.1.0 (0x00007fed28a2c000)
  $

  [acme@jouet perf]$ tools/perf/python/twatch.py
  cpu: 0, pid: 2817, tid: 2817 { type: fork, pid: 2817, ppid: 2817, tid: 8910, ptid: 2817, time: 11126454335306}
  cpu: 0, pid: 2817, tid: 2817 { type: comm, pid: 2817, tid: 8910, comm: worker }
  $ ps ax | grep twatch.py
   8909 pts/8    S+     0:00 /usr/bin/python tools/perf/python/twatch.py
  $ grep python /proc/8909/smaps
  5579de658000-5579de659000 r-xp 00000000 fd:00 3156044  /usr/bin/python2.7
  5579de858000-5579de859000 r--p 00000000 fd:00 3156044  /usr/bin/python2.7
  5579de859000-5579de85a000 rw-p 00001000 fd:00 3156044  /usr/bin/python2.7
  7f0de01f7000-7f0de023e000 r-xp 00000000 00:2d 230695   /tmp/build/perf/python/perf.so
  7f0de023e000-7f0de043d000 ---p 00047000 00:2d 230695   /tmp/build/perf/python/perf.so
  7f0de043d000-7f0de043e000 r--p 00046000 00:2d 230695   /tmp/build/perf/python/perf.so
  7f0de043e000-7f0de044b000 rw-p 00047000 00:2d 230695   /tmp/build/perf/python/perf.so
  7f0de6f0f000-7f0de6f13000 r-xp 00000000 fd:00 134975   /usr/lib64/python2.7/lib-dynload/_localemodule.so
  7f0de6f13000-7f0de7113000 ---p 00004000 fd:00 134975   /usr/lib64/python2.7/lib-dynload/_localemodule.so
  7f0de7113000-7f0de7114000 r--p 00004000 fd:00 134975   /usr/lib64/python2.7/lib-dynload/_localemodule.so
  7f0de7114000-7f0de7115000 rw-p 00005000 fd:00 134975   /usr/lib64/python2.7/lib-dynload/_localemodule.so
  7f0de7e73000-7f0de8052000 r-xp 00000000 fd:00 3173292  /usr/lib64/libpython2.7.so.1.0
  7f0de8052000-7f0de8251000 ---p 001df000 fd:00 3173292  /usr/lib64/libpython2.7.so.1.0
  7f0de8251000-7f0de8255000 r--p 001de000 fd:00 3173292  /usr/lib64/libpython2.7.so.1.0
  7f0de8255000-7f0de8291000 rw-p 001e2000 fd:00 3173292  /usr/lib64/libpython2.7.so.1.0
  $
Signed-off-by: NJaroslav Škarvada <jskarvad@redhat.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
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>
LPU-Reference: 20180119205641.24242-1-jskarvad@redhat.com
Link: https://lkml.kernel.org/n/tip-8d7dt9kqp83vsz25hagug8fu@git.kernel.org
[ Removed explicit check for python version, allowing it to really build with python3 ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This should speed up accessing new system calls introduced with the
kernel rather than waiting for libaudit updates to include them.

It also enables users to specify wildcards, for example, perf trace -e
'open*', just like was already possible on x86 and s390.
Signed-off-by: NRavi Bangoria <ravi.bangoria@linux.vnet.ibm.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 Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20180129083417.31240-4-ravi.bangoria@linux.vnet.ibm.com
[ Do it for ppc32 as well ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The Open CoreSight Decoding Library (openCSD) is a free and open library
to decode traces collected by the CoreSight hardware infrastructure.

This patch adds the required mechanic to recognise the presence of the
openCSD library on a system and set up miscellaneous flags to be used in
the compilation of the trace decoding feature.
Signed-off-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kim Phillips <kim.phillips@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Mike Leach <mike.leach@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Link: http://lkml.kernel.org/r/1516211539-5166-2-git-send-email-mathieu.poirier@linaro.org
Link: http://lkml.kernel.org/r/1516635644-24819-1-git-send-email-mathieu.poirier@linaro.org
[ Merged missing test-libopencsd.c file, provided later by Mathieu ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Change the Makefile and build process to no longer require audit-libs
interfaces when the architecture provides system call tables.

Committer notes:

Its not enough to hook into the NO_LIBAUDIT makefile block, we need to
define a CONFIG_TRACE that gets selected by both architectures
generating the syscall tables from the kernel headers and from detecting
the availability of libaudit.

With that in place we will not link against libaudit even if the
necessary files are available for that, in fact we will not even try to
detect its availability, speeding up a bit the feature detection phase.
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: linux-s390@vger.kernel.org
LPU-Reference: 1516352177-11106-6-git-send-email-brueckner@linux.vnet.ibm.com
Link: https://lkml.kernel.org/n/tip-j68lub6ipm8apvy52vd3l4cm@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Display the state of the rest of the features (FEATURE_TESTS_EXTRA) on a
'make VF=1' build. These features are detected manually by perf's
Makefile.config so they can't be displayed with the main list, but only
after we're done in Makefile.config.

  $ make VF=1
    BUILD:   Doing 'make -j4' parallel build

  Auto-detecting system features:
  ...                         dwarf: [ on  ]
  ...            dwarf_getlocations: [ on  ]
  ...                         glibc: [ on  ]
  ...                          gtk2: [ on  ]

SNIP

  ...                       timerfd: [ on  ]
  ...                  sched_getcpu: [ on  ]
  ...                           sdt: [ on  ]
  ...                         setns: [ on  ]

extra features:
  ...                        bionic: [ OFF ]
  ...                    compile-32: [ on  ]
  ...                   compile-x32: [ OFF ]
  ...                cplus-demangle: [ on  ]
  ...                         hello: [ OFF ]
  ...                 libbabeltrace: [ on  ]
  ...                       liberty: [ on  ]
  ...                     liberty-z: [ on  ]
  ...         libunwind-debug-frame: [ OFF ]
  ...     libunwind-debug-frame-arm: [ OFF ]
  ... libunwind-debug-frame-aarch64: [ OFF ]

SNIP
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180109092646.GB11520@kravaSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

There's no reason anymore to treat babel trace in a special way, because
a) we no longer display its state b) the needed babeltrace library is
now out and well adopted among distros.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180107160356.28203-2-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

On s390, object files must be compiled with position-indepedent code in
order to be incrementally linked or linked to shared libraries.

Therefore, add -fPIC to the CFLAGS for s390 to ensure each object file
is built properly.
Reported-by: NJonathan Hermann <jonathan.hermann@de.ibm.com>
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: linux s390 list <linux-s390@vger.kernel.org>
Link: https://lkml.kernel.org/r/20171207080951.GC4889@linux.vnet.ibm.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This one made x86 always build with -fPIC, when the intention was for
s390 to be built that way, due to a rebase mistake.
Reported-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
This reverts commit 1dc4ddf1.
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This should speed up accessing new system calls introduced with the
kernel rather than waiting for libaudit updates to include them.

It also enables users to specify wildcards, for example, perf trace -e
'open*', just like was already possible on x86.
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: linux-s390@vger.kernel.org
LPU-Reference: 1512635281-20733-2-git-send-email-brueckner@linux.vnet.ibm.com
Link: https://lkml.kernel.org/n/tip-htplh3nbrivi7g3cffbh4fsu@git.kernel.org
[ split from a larger patch ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

On Fedora systems the perl and python CFLAGS/LDFLAGS include the
hardened specs from redhat-rpm-config package. We apply them only for
perl/python objects, which makes them not compatible with the rest of
the objects and the build fails with:

  /usr/bin/ld: perf-in.o: relocation R_X86_64_32 against `.rodata.str1.1' can not be used when making a shared object; recompile with -f
+PIC
  /usr/bin/ld: libperf.a(libperf-in.o): relocation R_X86_64_32S against `.text' can not be used when making a shared object; recompile w
+ith -fPIC
  /usr/bin/ld: final link failed: Nonrepresentable section on output
  collect2: error: ld returned 1 exit status
  make[2]: *** [Makefile.perf:507: perf] Error 1
  make[1]: *** [Makefile.perf:210: sub-make] Error 2
  make: *** [Makefile:69: all] Error 2

Mainly it's caused by perl/python objects being compiled with:

  -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1

which prevent the final link impossible, because it will check
for 'proper' objects with following option:

  -specs=/usr/lib/rpm/redhat/redhat-hardened-ld
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20171204082437.GC30564@kravaSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Using the shell function for perl CFLAGS retrieval instead of back
quotes (``). Both execute shell with the command, but the latter is more
explicit and seems to be the preferred way.

Also we don't have any other use of the back quotes in perf Makefiles.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20171108102739.30338-2-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

On Fedora systems the perl and python CFLAGS/LDFLAGS include the
hardened specs from redhat-rpm-config package. We apply them only for
perl/python objects, which makes them not compatible with the rest of
the objects and the build fails with:

  /usr/bin/ld: perf-in.o: relocation R_X86_64_32 against `.rodata.str1.1' can not be used when making a shared object; recompile with -f
+PIC
  /usr/bin/ld: libperf.a(libperf-in.o): relocation R_X86_64_32S against `.text' can not be used when making a shared object; recompile w
+ith -fPIC
  /usr/bin/ld: final link failed: Nonrepresentable section on output
  collect2: error: ld returned 1 exit status
  make[2]: *** [Makefile.perf:507: perf] Error 1
  make[1]: *** [Makefile.perf:210: sub-make] Error 2
  make: *** [Makefile:69: all] Error 2

Mainly it's caused by perl/python objects being compiled with:

  -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1

which prevent the final link impossible, because it will check
for 'proper' objects with following option:

  -specs=/usr/lib/rpm/redhat/redhat-hardened-ld
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20171204082437.GC30564@kravaSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

On s390, object files must be compiled with position-indepedent code in
order to be incrementally linked or linked to shared libraries.
Therefore, add -fPIC to the CFLAGS for s390 to ensure each object file
is built properly.
Reported-by: NJonathan Hermann <jonathan.hermann@de.ibm.com>
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: linux s390 list <linux-s390@vger.kernel.org>
LPU-Reference: 1512031765-9382-1-git-send-email-brueckner@linux.vnet.ibm.com
Link: https://lkml.kernel.org/n/tip-a8wga8hrl0d0r84cal96fmgv@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

As 'perf bench futex wake-parallel" will use this, which is not
available in older systems such as versions of the android NDK used in
my container build tests (r12b and r15c at the moment).

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: James Yang <james.yang@arm.com
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kim Phillips <kim.phillips@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-1i7iv54in4wj08lwo55b0pzv@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Using the shell function for perl CFLAGS retrieval instead of back
quotes (``). Both execute shell with the command, but the latter is more
explicit and seems to be the preferred way.

Also we don't have any other use of the back quotes in perf Makefiles.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20171108102739.30338-2-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

With support for perf_regs and libdw, you can record and report
call graphs for user space programs. Simply invoke perf with
the --call-graph=dwarf command line option.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
[brueckner: added dwfl_thread_state_register_pc() call]
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-and-tested-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Prior to this patch, make scripts tested for CLANG with ifeq ($(CC),
clang), failing to detect CLANG binaries with different names. Fix it by
testing for the existence of __clang__ macro in the list of compiler
defined macros.
Signed-off-by: NDavid Carrillo-Cisneros <davidcc@google.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Paul Turner <pjt@google.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20170827075442.108534-5-davidcc@google.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

* libunwind-x86_64 must be linked before libunwind
* libunwind requires liblzma
* static libunwind conflicts with static libgcc_eh
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/150322917247.129799.14247751517961953155.stgit@buzzSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Fix feature test for static libdw: link required dependencies.  Backends
of libebl are not statically linked thus libdl is required.

In Debian/Ubuntu libdw-dev includes libebl.a starting from 0.166-1.
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/150322916720.129772.7959925864494283854.stgit@buzzSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

And provide an alternative implementation to keep perf building on older
distros as we're about to add initial support for namespaces.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Krister Johansen <kjlx@templeofstupid.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-bqdwijunhjlvps1ardykhw1i@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Porting PPC to libdw only needs an architecture-specific hook to move
the register state from perf to libdw.

The ARM and x86 architectures already use libdw, and it is useful to
have as much common code for the unwinder as possible.  Mark Wielaard
has contributed a frame-based unwinder to libdw, so that unwinding works
even for binaries that do not have CFI information.  In addition,
libunwind is always preferred to libdw by the build machinery so this
cannot introduce regressions on machines that have both libunwind and
libdw installed.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Acked-by: NMilian Wolff <milian.wolff@kdab.com>
Acked-by: NRavi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1496312681-20133-1-git-send-email-pbonzini@redhat.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

With commit: 0a943cb1 (tools build: Add HOSTARCH Makefile variable)
when building for ARCH=x86_64, ARCH=x86_64 is passed to perf instead of
ARCH=x86, so the perf build process searchs header files from
tools/arch/x86_64/include, which doesn't exist.

The following build failure is seen:

  In file included from util/event.c:2:0:
    tools/include/uapi/linux/mman.h:4:27: fatal error: uapi/asm/mman.h: No such file or directory
    compilation terminated.

Fix this issue by using SRCARCH instead of ARCH in perf, just like the
main kernel Makefile and tools/objtool's.
Signed-off-by: NJiada Wang <jiada_wang@mentor.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Eugeniu Rosca <erosca@de.adit-jv.com>
Cc: Jan Stancek <jstancek@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Rui Teng <rui.teng@linux.vnet.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: 0a943cb1 ("tools build: Add HOSTARCH Makefile variable")
Link: http://lkml.kernel.org/r/1491793357-14977-2-git-send-email-jiada_wang@mentor.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The build of JVMTI depends on LIBELF (-lelf). Make Makefile.conf
check this dependendancy and notify user when not present.

v2: Comma nitpicking.
Signed-off-by: NDavid Carrillo-Cisneros <davidcc@google.com>
Tested-by: NKim Phillips <kim.phillips@arm.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Simon Que <sque@chromium.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20170412170745.26620-1-davidcc@google.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

( This is a rebased version of https://lkml.org/lkml/2017/2/7/662 )

Python's CC and link Makefile variables were not passed to feature
detection, causing feature detection to use system's Python rather than
PYTHON_CONFIG's one. This created a mismatch between the detected Python
support and the one actually used by perf when PYTHON_CONFIG is
specified.

Fix it by moving Python's variable initialization to before feature
detection and pass FLAGS_PYTHON_EMBED to Python's feature detection's
build target.
Signed-off-by: NDavid Carrillo-Cisneros <davidcc@google.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Simon Que <sque@chromium.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20170412064919.92449-2-davidcc@google.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Instead of trying to go on adding more ifdef conditions, do a feature
test and define HAVE_SCHED_GETCPU_SUPPORT instead, then use it to
provide the prototype. No need to change the stub, as it is already a
__weak symbol.

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-yge89er9g90sc0v6k0a0r5tr@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Gcc has a -spec option to override what options to pass to cc, etc, and
in some distros this is used, like in fedora, where we end up getting
this passed to gcc that makes clang, that doesn't have this option to
stop the build:

  CC       /tmp/build/perf/util/scripting-engines/trace-event-python.o
clang-4.0: error: argument unused during compilation: '-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1' [-Werror,-Wunused-command-line-argument]

So filter this out when the compiler used is clang, this way we
can build the python scripting support in tools/perf/.

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-2gosxoiouf24pnlknp7w7q4z@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

To avoid this when using clang:

  warning: optimization level '-O6' is not supported; using '-O3' instead

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-kaghp8ddvzdsg03putemcq96@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Don't warn for feature-dwarf==0 if user explicitily disabled DWARF by
using NO_DWARF=1.
Signed-off-by: NDavid Carrillo-Cisneros <davidcc@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20170112210159.76143-1-davidcc@google.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Cancel builtin llvm and clang support when LLVM version is less than
3.9.0: following commits uses newer API.

Since Clang/LLVM's API is not guaranteed to be stable, add a
test-llvm-version.cpp feature checker, issue warning if LLVM found in
compiling environment is not tested yet.

Committer Notes:

Testing it:

Environment:

  $ cat /etc/fedora-release
  Fedora release 25 (Twenty Five)
  $ rpm -q llvm-devel clang-devel
  llvm-devel-3.8.0-1.fc25.x86_64
  clang-devel-3.8.0-2.fc25.x86_64
  $

Before:

  $  make -k LIBCLANGLLVM=1 O=/tmp/build/perf -C tools/perf install-bin
  make: Entering directory '/home/acme/git/linux/tools/perf'
    BUILD:   Doing 'make -j4' parallel build
  Warning: tools/include/uapi/linux/bpf.h differs from kernel
  Warning: tools/arch/arm/include/uapi/asm/kvm.h differs from kernel
    INSTALL  GTK UI
    LINK     /tmp/build/perf/perf
  /tmp/build/perf/libperf.a(libperf-in.o): In function `perf::createCompilerInvocation(llvm::SmallVector<char const*, 16u>, llvm::StringRef&, clang::DiagnosticsEngine&)':
  /home/acme/git/linux/tools/perf/util/c++/clang.cpp:56: undefined reference to `clang::tooling::newInvocation(clang::DiagnosticsEngine*, llvm::SmallVector<char const*, 16u> const&)'
  /tmp/build/perf/libperf.a(libperf-in.o): In function `perf::getModuleFromSource(llvm::SmallVector<char const*, 16u>, llvm::StringRef, llvm::IntrusiveRefCntPtr<clang::vfs::FileSystem>)':
  /home/acme/git/linux/tools/perf/util/c++/clang.cpp:68: undefined reference to `clang::CompilerInstance::CompilerInstance(std::shared_ptr<clang::PCHContainerOperations>, bool)'
  /home/acme/git/linux/tools/perf/util/c++/clang.cpp:69: undefined reference to `clang::CompilerInstance::createDiagnostics(clang::DiagnosticConsumer*, bool)'
  <SNIP>

After:

  Makefile.config:807: No suitable libLLVM found, disabling builtin clang and llvm support. Please install llvm-dev(el) (>= 3.9.0)

Updating the environment to a locally built LLVM 4.0 + clang 3.9 (forgot
to git pull, duh) combo, all works as expected, it is properly detected
and built into the resulting perf binary.
Signed-off-by: NWang Nan <wangnan0@huawei.com>
Reported-and-Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Stringer <joe@ovn.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161206072230.7651-1-wangnan0@huawei.com
[ Change the warning message a bit (add 'suitable' and 'builtin'), clarifying it, see committer notes above ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Allow C++ code to use util.h and tests/llvm.h. Let 'perf test' compile a
real BPF script.
Signed-off-by: NWang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Stringer <joe@ovn.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161126070354.141764-14-wangnan0@huawei.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Add necessary c++ flags and link libraries to support builtin clang and
LLVM. Add all llvm and clang libraries, so don't need to worry about
clang changes its libraries setting. However, linking perf would take
much longer than usual.
Signed-off-by: NWang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Stringer <joe@ovn.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161126070354.141764-10-wangnan0@huawei.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Compile jvmti agent as part of the perf build. The agent library is
called libperf-jvmti.so and is installed in default place together with
other files:

  $ make libperf-jvmti.so
    BUILD:   Doing 'make -j4' parallel build
    ...
    CC       jvmti/libjvmti.o
    CC       jvmti/jvmti_agent.o
    LD       jvmti/jvmti-in.o
    LINK     libperf-jvmti.so

  $ make DESTDIR=/tmp/krava/ install-bin
  ...
  $ find /tmp/krava/ | grep libperf
  /tmp/krava/lib64/libperf-jvmti.so
  /tmp/krava/lib64/libperf-gtk.so
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: NStephane Eranian <eranian@google.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: William Cohen <wcohen@redhat.com>
Link: http://lkml.kernel.org/r/1478093749-5602-4-git-send-email-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This patch modifies the build dependencies on the jitdump support in
perf. As it stands jitdump was wrongfully made dependent 100% on using
DWARF. However, the dwarf dependency, only exist if generating the
source line table in genelf_debug.c. The rest of the support does not
need DWARF.

This patch removes the dependency on DWARF for the entire jitdump
support. It keeps it only for the genelf_debug.c support.
Signed-off-by: NMaciej Debski <maciejd@google.com>
Reviewed-by: NStephane Eranian <eranian@google.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1476356383-30100-3-git-send-email-eranian@google.com
Fixes: e12b202f ("perf jitdump: Build only on supported archs")
[ Make it build only if NO_LIBELF isn't defined, as jitdump.o will only be built in that case ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The __get_cpuid() test is only valid when compiling for x86.  When
compiling for other architectures like ARM/ARM64 the test fails event if
the functionality is not required.

This patch isolate the build-in feature check to x86 platform, allowing
the compilation and usage of PMUs that use the AUXTRACE infrastructure
on other architectures (i.e ARM CoreSight).
Signed-off-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: NAdrian Hunter <adrian.hunter@intel.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1474041004-13956-2-git-send-email-mathieu.poirier@linaro.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

There's no reason to keep it in separate directory now when we moved out
the rest of the files.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1470074555-24889-6-git-send-email-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This checks whether sys/sdt.h is available or not, which is required for
DTRACE_PROBE().

We can disable this feature by passing NO_SDT=1 when building.

This flag will be used for SDT test case and further SDT events in
perftools.
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/146831795615.17065.17513820540591053933.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

That is not present on some libelf implementations, such as the one used
in Alpine Linux: libelf-0.8.13.

This ends up disabling the SDT code, that relies on this function.

One alternative would be to provide an weak fallback implementation or
the open coded variant used by the buildid sysfs notes reading code.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-82lh22ybedy9b9lych8xj12g@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>