The LBR stitch approach should be disabled by default. Because

- The stitching approach base on LBR call stack technology. The known
  limitations of LBR call stack technology still apply to the approach,
  e.g. Exception handing such as setjmp/longjmp will have calls/returns
  not match.

- This approach is not foolproof. There can be cases where it creates
  incorrect call stacks from incorrect matches. There is no attempt to
  validate any matches in another way.

The 'lbr_stitch_enable' is used to indicate whether enable LBR stitch
approach, which is disabled by default. The following patch will
introduce a new option for each tools to enable the LBR stitch
approach.
Signed-off-by: NKan Liang <kan.liang@linux.intel.com>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-10-kan.liang@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Both caller and callee needs to add ip from LBR to callchain.
Factor out lbr_callchain_add_lbr_ip() to improve code readability.
Signed-off-by: NKan Liang <kan.liang@linux.intel.com>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-9-kan.liang@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Both caller and callee needs to add kernel ip to callchain.  Factor out
lbr_callchain_add_kernel_ip() to improve code readability.
Signed-off-by: NKan Liang <kan.liang@linux.intel.com>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-8-kan.liang@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

LBR only collect the user call stack. To reconstruct a call stack, both
kernel call stack and user call stack are required. The function
resolve_lbr_callchain_sample() mix the kernel call stack and user call
stack.

Now, with the help of HW idx, perf tool can reconstruct a more complete
call stack by adding some user call stack from previous sample. However,
current implementation is hard to be extended to support it.

Current code path for resolve_lbr_callchain_sample()

  for (j = 0; j < mix_chain_nr; j++) {
       if (ORDER_CALLEE) {
             if (kernel callchain)
                  Fill callchain info
             else if (LBR callchain)
                  Fill callchain info
       } else {
             if (LBR callchain)
                  Fill callchain info
             else if (kernel callchain)
                  Fill callchain info
       }
       add_callchain_ip();
  }

With the patch,

  if (ORDER_CALLEE) {
       for (j = 0; j < NUM of kernel callchain) {
             Fill callchain info
             add_callchain_ip();
       }
       for (; j < mix_chain_nr) {
             Fill callchain info
             add_callchain_ip();
       }
  } else {
       for (; j < NUM of LBR callchain) {
             Fill callchain info
             add_callchain_ip();
       }
       for (j = 0; j < mix_chain_nr) {
             Fill callchain info
             add_callchain_ip();
       }
  }

No functional changes.
Signed-off-by: NKan Liang <kan.liang@linux.intel.com>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-7-kan.liang@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The indent is unnecessary in resolve_lbr_callchain_sample.  Removing it
will make the following patch simpler.

Current code path for resolve_lbr_callchain_sample()

        /* LBR only affects the user callchain */
        if (i != chain_nr) {
                body of the function
                ....
                return 1;
        }

        return 0;

With the patch,

        /* LBR only affects the user callchain */
        if (i == chain_nr)
                return 0;

        body of the function
        ...
        return 1;

No functional changes.
Signed-off-by: NKan Liang <kan.liang@linux.intel.com>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-6-kan.liang@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

To stitch LBR call stack, the max LBR information is required. So the
CPU PMU capabilities information has to be stored in perf header.

Add a new feature HEADER_CPU_PMU_CAPS for CPU PMU capabilities.
Retrieve all CPU PMU capabilities, not just max LBR information.

Add variable max_branches to facilitate future usage.

Committer testing:

  # ls -la /sys/devices/cpu/caps/
  total 0
  drwxr-xr-x. 2 root root    0 Apr 17 10:53 .
  drwxr-xr-x. 6 root root    0 Apr 17 07:02 ..
  -r--r--r--. 1 root root 4096 Apr 17 10:53 max_precise
  #
  # cat /sys/devices/cpu/caps/max_precise
  0
  # perf record sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.033 MB perf.data (7 samples) ]
  #
  # perf report --header-only | egrep 'cpu(desc|.*capabilities)'
  # cpudesc : AMD Ryzen 5 3600X 6-Core Processor
  # cpu pmu capabilities: max_precise=0
  #

And then on an Intel machine:

  $ ls -la /sys/devices/cpu/caps/
  total 0
  drwxr-xr-x. 2 root root    0 Apr 17 10:51 .
  drwxr-xr-x. 6 root root    0 Apr 17 10:04 ..
  -r--r--r--. 1 root root 4096 Apr 17 11:37 branches
  -r--r--r--. 1 root root 4096 Apr 17 10:51 max_precise
  -r--r--r--. 1 root root 4096 Apr 17 11:37 pmu_name
  $ cat /sys/devices/cpu/caps/max_precise
  3
  $ cat /sys/devices/cpu/caps/branches
  32
  $ cat /sys/devices/cpu/caps/pmu_name
  skylake
  $ perf record sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.001 MB perf.data (8 samples) ]
  $ perf report --header-only | egrep 'cpu(desc|.*capabilities)'
  # cpudesc : Intel(R) Core(TM) i5-7500 CPU @ 3.40GHz
  # cpu pmu capabilities: branches=32, max_precise=3, pmu_name=skylake
  $
Signed-off-by: NKan Liang <kan.liang@linux.intel.com>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-3-kan.liang@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The current rXXXX event specification creates event under PERF_TYPE_RAW
pmu type. This change allows to use rXXXX within pmu syntax, so it's
type is used via the following syntax:

  -e 'cpu/r3c/'
  -e 'cpum_cf/r0/'

The XXXX number goes directly to perf_event_attr::config the same way as
in '-e rXXXX' event. The perf_event_attr::type is filled with pmu type.

Committer testing:

So, lets see what goes in perf_event_attr::config for, say, the
'instructions' PERF_TYPE_HARDWARE (0) event, first we should look at how
to encode this event as a PERF_TYPE_RAW event for this specific CPU, an
AMD Ryzen 5:

  # cat /sys/devices/cpu/events/instructions
  event=0xc0
  #

Then try with it _and_ the instruction, just to see that they are close
enough:

  # perf stat -e rc0,instructions sleep 1

   Performance counter stats for 'sleep 1':

             919,794      rc0
             919,898      instructions

         1.000754579 seconds time elapsed

         0.000715000 seconds user
         0.000000000 seconds sys
  #

Now we should try, before this patch, the PMU event encoding:

  # perf stat -e cpu/rc0/ sleep 1
  event syntax error: 'cpu/rc0/'
                           \___ unknown term

  valid terms: event,edge,inv,umask,cmask,config,config1,config2,name,period,percore
  #

Now with this patch, the three ways of specifying the 'instructions' CPU
counter are accepted:

  # perf stat -e cpu/rc0/,rc0,instructions sleep 1

   Performance counter stats for 'sleep 1':

             892,948      cpu/rc0/
             893,052      rc0
             893,156      instructions

         1.000931819 seconds time elapsed

         0.000916000 seconds user
         0.000000000 seconds sys

  #
Requested-by: NThomas Richter <tmricht@linux.ibm.com>
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: NThomas Richter <tmricht@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: http://lore.kernel.org/lkml/20200416221405.437788-1-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This will allow parent makefiles to pass values to asciidoc.
Signed-off-by: NIan Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Jiwei Sun <jiwei.sun@windriver.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: yuzhoujian <yuzhoujian@didichuxing.com>
Link: http://lore.kernel.org/lkml/20200416162058.201954-2-irogers@google.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The PMU capabilities information, which is located at
/sys/bus/event_source/devices/<dev>/caps, is required by perf tool.  For
example, the max LBR information is required to stitch LBR call stack.

Add perf_pmu__caps_parse() to parse the PMU capabilities information.
The information is stored in a list.

The following patch will store the capabilities information in perf
header.

Committer notes:

Here's an example of such directories and its files in an i5 7th gen
machine:

  [root@seventh ~]# ls -lad /sys/bus/event_source/devices/*/caps
  drwxr-xr-x. 2 root root 0 Apr 14 13:33 /sys/bus/event_source/devices/cpu/caps
  drwxr-xr-x. 2 root root 0 Apr 14 13:33 /sys/bus/event_source/devices/intel_pt/caps
  [root@seventh ~]# ls -la /sys/bus/event_source/devices/intel_pt/caps
  total 0
  drwxr-xr-x. 2 root root    0 Apr 14 13:33 .
  drwxr-xr-x. 5 root root    0 Apr 14 13:12 ..
  -r--r--r--. 1 root root 4096 Apr 16 13:10 cr3_filtering
  -r--r--r--. 1 root root 4096 Apr 16 11:42 cycle_thresholds
  -r--r--r--. 1 root root 4096 Apr 16 13:10 ip_filtering
  -r--r--r--. 1 root root 4096 Apr 16 13:10 max_subleaf
  -r--r--r--. 1 root root 4096 Apr 14 13:33 mtc
  -r--r--r--. 1 root root 4096 Apr 14 13:33 mtc_periods
  -r--r--r--. 1 root root 4096 Apr 16 13:10 num_address_ranges
  -r--r--r--. 1 root root 4096 Apr 16 13:10 output_subsys
  -r--r--r--. 1 root root 4096 Apr 16 13:10 payloads_lip
  -r--r--r--. 1 root root 4096 Apr 16 13:10 power_event_trace
  -r--r--r--. 1 root root 4096 Apr 14 13:33 psb_cyc
  -r--r--r--. 1 root root 4096 Apr 14 13:33 psb_periods
  -r--r--r--. 1 root root 4096 Apr 16 13:10 ptwrite
  -r--r--r--. 1 root root 4096 Apr 16 13:10 single_range_output
  -r--r--r--. 1 root root 4096 Apr 16 12:03 topa_multiple_entries
  -r--r--r--. 1 root root 4096 Apr 16 13:10 topa_output
  [root@seventh ~]# cat /sys/bus/event_source/devices/intel_pt/caps/topa_output
  1
  [root@seventh ~]# cat /sys/bus/event_source/devices/intel_pt/caps/topa_multiple_entries
  1
  [root@seventh ~]# cat /sys/bus/event_source/devices/intel_pt/caps/mtc
  1
  [root@seventh ~]# cat /sys/bus/event_source/devices/intel_pt/caps/power_event_trace
  0
  [root@seventh ~]#

  [root@seventh ~]# ls -la /sys/bus/event_source/devices/cpu/caps/
  total 0
  drwxr-xr-x. 2 root root    0 Apr 14 13:33 .
  drwxr-xr-x. 6 root root    0 Apr 14 13:12 ..
  -r--r--r--. 1 root root 4096 Apr 16 13:10 branches
  -r--r--r--. 1 root root 4096 Apr 14 13:33 max_precise
  -r--r--r--. 1 root root 4096 Apr 16 13:10 pmu_name
  [root@seventh ~]# cat /sys/bus/event_source/devices/cpu/caps/max_precise
  3
  [root@seventh ~]# cat /sys/bus/event_source/devices/cpu/caps/branches
  32
  [root@seventh ~]# cat /sys/bus/event_source/devices/cpu/caps/pmu_name
  skylake
  [root@seventh ~]#

Wow, first time I've heard about
/sys/bus/event_source/devices/cpu/caps/max_precise, I think I'll use it!
:-)
Signed-off-by: NKan Liang <kan.liang@linux.intel.com>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-2-kan.liang@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

According to the API, if memory allocation wasn't possible, or some
other error occurs, asprintf will return -1, and the contents of strp
below are undefined.

  int asprintf(char **strp, const char *fmt, ...);

This patch takes care of return value of asprintf to make it less error
prone and prevent the following build warning.

  ignoring return value of ‘asprintf’, declared with attribute warn_unused_result [-Wunused-result]
Signed-off-by: NHe Zhe <zhe.he@windriver.com>
Reviewed-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: hewenliang4@huawei.com
Link: http://lore.kernel.org/lkml/1582163930-233692-1-git-send-email-zhe.he@windriver.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

When it is not possible for a non-privilege perf command to monitor at
the kernel level (:k), the fallback code forces a :u. That works if the
event was previously monitoring both levels.  But if the event was
already constrained to kernel only, then it does not make sense to
restrict it to user only.

Given the code works by exclusion, a kernel only event would have:

  attr->exclude_user = 1

The fallback code would add:

  attr->exclude_kernel = 1

In the end the end would not monitor in either the user level or kernel
level. In other words, it would count nothing.

An event programmed to monitor kernel only cannot be switched to user
only without seriously warning the user.

This patch forces an error in this case to make it clear the request
cannot really be satisfied.

Behavior with paranoid 1:

  $ sudo bash -c "echo 1 > /proc/sys/kernel/perf_event_paranoid"
  $ perf stat -e cycles:k sleep 1

   Performance counter stats for 'sleep 1':

           1,520,413      cycles:k

         1.002361664 seconds time elapsed

         0.002480000 seconds user
         0.000000000 seconds sys

Old behavior with paranoid 2:

  $ sudo bash -c "echo 2 > /proc/sys/kernel/perf_event_paranoid"
  $ perf stat -e cycles:k sleep 1
   Performance counter stats for 'sleep 1':

                   0      cycles:ku

         1.002358127 seconds time elapsed

         0.002384000 seconds user
         0.000000000 seconds sys

New behavior with paranoid 2:

  $ sudo bash -c "echo 2 > /proc/sys/kernel/perf_event_paranoid"
  $ perf stat -e cycles:k sleep 1
  Error:
  You may not have permission to collect stats.

  Consider tweaking /proc/sys/kernel/perf_event_paranoid,
  which controls use of the performance events system by
  unprivileged users (without CAP_PERFMON or CAP_SYS_ADMIN).

  The current value is 2:

    -1: Allow use of (almost) all events by all users
        Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
  >= 0: Disallow ftrace function tracepoint by users without CAP_PERFMON or CAP_SYS_ADMIN
        Disallow raw tracepoint access by users without CAP_SYS_PERFMON or CAP_SYS_ADMIN
  >= 1: Disallow CPU event access by users without CAP_PERFMON or CAP_SYS_ADMIN
  >= 2: Disallow kernel profiling by users without CAP_PERFMON or CAP_SYS_ADMIN

  To make this setting permanent, edit /etc/sysctl.conf too, e.g.:

          kernel.perf_event_paranoid = -1

v2 of this patch addresses the review feedback from jolsa@redhat.com.
Signed-off-by: NStephane Eranian <eranian@google.com>
Reviewed-by: NIan Rogers <irogers@google.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200414161550.225588-1-irogers@google.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

When AUX area events are used in sampling mode, they must be the group
leader, but the group leader is also used for leader-sampling. However,
it is not desirable to use an AUX area event as the leader for
leader-sampling, because it doesn't have any samples of its own. To support
leader-sampling with AUX area events, use the 2nd event of the group as the
"leader" for the purposes of leader-sampling.

Example:

 # perf record --kcore --aux-sample -e '{intel_pt//,cycles,instructions}:S' -c 10000 uname
 [ perf record: Woken up 3 times to write data ]
 [ perf record: Captured and wrote 0.786 MB perf.data ]
 # perf report
 Samples: 380  of events 'anon group { cycles, instructions }', Event count (approx.): 3026164
           Children              Self  Command  Shared Object      Symbol
 +   38.76%  42.65%     0.00%   0.00%  uname    [kernel.kallsyms]  [k] __x86_indirect_thunk_rax
 +   35.82%  31.33%     0.00%   0.00%  uname    ld-2.28.so         [.] _dl_start_user
 +   34.29%  29.74%     0.55%   0.47%  uname    ld-2.28.so         [.] _dl_start
 +   33.73%  28.62%     1.60%   0.97%  uname    ld-2.28.so         [.] dl_main
 +   33.19%  29.04%     0.52%   0.32%  uname    ld-2.28.so         [.] _dl_sysdep_start
 +   27.83%  33.74%     0.00%   0.00%  uname    [kernel.kallsyms]  [k] do_syscall_64
 +   26.76%  33.29%     0.00%   0.00%  uname    [kernel.kallsyms]  [k] entry_SYSCALL_64_after_hwframe
 +   23.78%  20.33%     5.97%   5.25%  uname    [kernel.kallsyms]  [k] page_fault
 +   23.18%  24.60%     0.00%   0.00%  uname    libc-2.28.so       [.] __libc_start_main
 +   22.64%  24.37%     0.00%   0.00%  uname    uname              [.] _start
 +   21.04%  23.27%     0.00%   0.00%  uname    uname              [.] main
 +   19.48%  18.08%     3.72%   3.64%  uname    ld-2.28.so         [.] _dl_relocate_object
 +   19.47%  21.81%     0.00%   0.00%  uname    libc-2.28.so       [.] setlocale
 +   19.44%  21.56%     0.52%   0.61%  uname    libc-2.28.so       [.] _nl_find_locale
 +   17.87%  19.66%     0.00%   0.00%  uname    libc-2.28.so       [.] _nl_load_locale_from_archive
 +   15.71%  13.73%     0.53%   0.52%  uname    [kernel.kallsyms]  [k] do_page_fault
 +   15.18%  13.21%     1.03%   0.68%  uname    [kernel.kallsyms]  [k] handle_mm_fault
 +   14.15%  12.53%     1.01%   1.12%  uname    [kernel.kallsyms]  [k] __handle_mm_fault
 +   12.03%   9.67%     0.54%   0.32%  uname    ld-2.28.so         [.] _dl_map_object
 +   10.55%   8.48%     0.00%   0.00%  uname    ld-2.28.so         [.] openaux
 +   10.55%  20.20%     0.52%   0.61%  uname    libc-2.28.so       [.] __run_exit_handlers

Comnmitter notes:

Fixed up this problem:

  util/record.c: In function ‘perf_evlist__config’:
  util/record.c:256:3: error: too few arguments to function ‘perf_evsel__config_leader_sampling’
    256 |   perf_evsel__config_leader_sampling(evsel);
        |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  util/record.c:190:13: note: declared here
    190 | static void perf_evsel__config_leader_sampling(struct evsel *evsel,
        |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-17-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Tools find the correct evsel, and therefore read format, using the event
ID, so it isn't necessary for all read formats to be the same. In the
case of leader-sampling of AUX area events, dummy tracking events will
have a different read format, so relax the validation to become a debug
message only.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-16-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

In preparation for adding support for leader sampling with AUX area events.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-15-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move leader-sampling configuration in preparation for adding support for
leader sampling with AUX area events.

Committer notes:

It only makes sense when configuring an evsel that is part of an evlist,
so the only case where it is called outside perf_evlist__config(), in
some 'perf test' entry, is safe, and even there we should just use
perf_evlist__config(), but since in that case we have just one evsel in
the evlist, it is equivalent.

Also fixed up this problem:

  util/record.c: In function ‘perf_evlist__config’:
  util/record.c:223:3: error: too many arguments to function ‘perf_evsel__config_leader_sampling’
    223 |   perf_evsel__config_leader_sampling(evsel, evlist);
        |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  util/record.c:170:13: note: declared here
    170 | static void perf_evsel__config_leader_sampling(struct evsel *evsel)
        |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-14-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move and globalize 2 functions from the auxtrace specific sources so
that they can be reused.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-13-adrian.hunter@intel.com
[ Move to pmu.c, as moving to evsel.h breaks the python binding ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Currently, callchains can be synthesized only for synthesized events.
Support also synthesizing callchains for regular events.

Example:

 # perf record --kcore --aux-sample -e '{intel_pt//,cycles}' -c 10000 uname
 Linux
 [ perf record: Woken up 3 times to write data ]
 [ perf record: Captured and wrote 0.532 MB perf.data ]
 # perf script --itrace=Ge | head -20
 uname  4864 2419025.358181:      10000     cycles:
        ffffffffbba56965 apparmor_bprm_committing_creds+0x35 ([kernel.kallsyms])
        ffffffffbc400cd5 __indirect_thunk_start+0x5 ([kernel.kallsyms])
        ffffffffbba07422 security_bprm_committing_creds+0x22 ([kernel.kallsyms])
        ffffffffbb89805d install_exec_creds+0xd ([kernel.kallsyms])
        ffffffffbb90d9ac load_elf_binary+0x3ac ([kernel.kallsyms])

 uname  4864 2419025.358185:      10000     cycles:
        ffffffffbba56db0 apparmor_bprm_committed_creds+0x20 ([kernel.kallsyms])
        ffffffffbc400cd5 __indirect_thunk_start+0x5 ([kernel.kallsyms])
        ffffffffbba07452 security_bprm_committed_creds+0x22 ([kernel.kallsyms])
        ffffffffbb89809a install_exec_creds+0x4a ([kernel.kallsyms])
        ffffffffbb90d9ac load_elf_binary+0x3ac ([kernel.kallsyms])

 uname  4864 2419025.358189:      10000     cycles:
        ffffffffbb86fdf6 vma_adjust_trans_huge+0x6 ([kernel.kallsyms])
        ffffffffbb821660 __vma_adjust+0x160 ([kernel.kallsyms])
        ffffffffbb897be7 shift_arg_pages+0x97 ([kernel.kallsyms])
        ffffffffbb897ed9 setup_arg_pages+0x1e9 ([kernel.kallsyms])
        ffffffffbb90d9f2 load_elf_binary+0x3f2 ([kernel.kallsyms])

Committer testing:

  # perf record --kcore --aux-sample -e '{intel_pt//,cycles}' -c 10000 uname
  Linux
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.233 MB perf.data ]
  #

Then, before this patch:

  # perf script --itrace=Ge | head -20
     uname 28642 168664.856384: 10000 cycles: ffffffff9810aeaa commit_creds+0x2a ([kernel.kallsyms])
     uname 28642 168664.856388: 10000 cycles: ffffffff982a24f1 mprotect_fixup+0x151 ([kernel.kallsyms])
     uname 28642 168664.856392: 10000 cycles: ffffffff982a385b move_page_tables+0xbcb ([kernel.kallsyms])
     uname 28642 168664.856396: 10000 cycles: ffffffff982fd4ec __mod_memcg_state+0x1c ([kernel.kallsyms])
     uname 28642 168664.856400: 10000 cycles: ffffffff9829fddd do_mmap+0xfd ([kernel.kallsyms])
     uname 28642 168664.856404: 10000 cycles: ffffffff9829c879 __vma_adjust+0x479 ([kernel.kallsyms])
     uname 28642 168664.856408: 10000 cycles: ffffffff98238e94 __perf_addr_filters_adjust+0x34 ([kernel.kallsyms])
     uname 28642 168664.856412: 10000 cycles: ffffffff98a38e0b down_write+0x1b ([kernel.kallsyms])
     uname 28642 168664.856416: 10000 cycles: ffffffff983006a0 memcg_kmem_get_cache+0x0 ([kernel.kallsyms])
     uname 28642 168664.856421: 10000 cycles: ffffffff98396eaf load_elf_binary+0x92f ([kernel.kallsyms])
     uname 28642 168664.856425: 10000 cycles: ffffffff982e0222 kfree+0x62 ([kernel.kallsyms])
     uname 28642 168664.856428: 10000 cycles: ffffffff9846dfd4 file_has_perm+0x54 ([kernel.kallsyms])
     uname 28642 168664.856433: 10000 cycles: ffffffff98288911 vma_interval_tree_insert+0x51 ([kernel.kallsyms])
     uname 28642 168664.856437: 10000 cycles: ffffffff9823e577 perf_event_mmap_output+0x27 ([kernel.kallsyms])
     uname 28642 168664.856441: 10000 cycles: ffffffff98a26fa0 xas_load+0x40 ([kernel.kallsyms])
     uname 28642 168664.856445: 10000 cycles: ffffffff98004f30 arch_setup_additional_pages+0x0 ([kernel.kallsyms])
     uname 28642 168664.856448: 10000 cycles: ffffffff98a297c0 copy_user_generic_unrolled+0xa0 ([kernel.kallsyms])
     uname 28642 168664.856452: 10000 cycles: ffffffff9853a87a strnlen_user+0x10a ([kernel.kallsyms])
     uname 28642 168664.856456: 10000 cycles: ffffffff986638a7 randomize_page+0x27 ([kernel.kallsyms])
     uname 28642 168664.856460: 10000 cycles: ffffffff98a3b645 _raw_spin_lock+0x5 ([kernel.kallsyms])

  #

And after:

  # perf script --itrace=Ge | head -20
  uname 28642 168664.856384:      10000     cycles:
  	ffffffff9810aeaa commit_creds+0x2a ([kernel.kallsyms])
  	ffffffff9831fe87 install_exec_creds+0x17 ([kernel.kallsyms])
  	ffffffff983968d9 load_elf_binary+0x359 ([kernel.kallsyms])
  	ffffffff98e00c45 __x86_indirect_thunk_rax+0x5 ([kernel.kallsyms])
  	ffffffff98e00c45 __x86_indirect_thunk_rax+0x5 ([kernel.kallsyms])

  uname 28642 168664.856388:      10000     cycles:
  	ffffffff982a24f1 mprotect_fixup+0x151 ([kernel.kallsyms])
  	ffffffff9831fa83 setup_arg_pages+0x123 ([kernel.kallsyms])
  	ffffffff9839691f load_elf_binary+0x39f ([kernel.kallsyms])
  	ffffffff98e00c45 __x86_indirect_thunk_rax+0x5 ([kernel.kallsyms])
  	ffffffff98e00c45 __x86_indirect_thunk_rax+0x5 ([kernel.kallsyms])

  uname 28642 168664.856392:      10000     cycles:
  	ffffffff982a385b move_page_tables+0xbcb ([kernel.kallsyms])
  	ffffffff9831f889 shift_arg_pages+0xa9 ([kernel.kallsyms])
  	ffffffff9831fb4f setup_arg_pages+0x1ef ([kernel.kallsyms])
  	ffffffff9839691f load_elf_binary+0x39f ([kernel.kallsyms])
  	ffffffff98e00c45 __x86_indirect_thunk_rax+0x5 ([kernel.kallsyms])
  #
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-12-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

For reporting purposes, an evsel sample can have a callchain synthesized
from AUX area data. Add support for keeping track of synthesized sample
types. Note, the recorded sample_type cannot be changed because it is
needed to continue to parse events.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-11-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Using 'type' variable for checking for callchains is equivalent to using
evsel__has_callchain(evsel) and is how the other PERF_SAMPLE_ bits are checked
in this function, so use it to be consistent.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-11-adrian.hunter@intel.com
[ split from a larger patch ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Add a thread stack function to create a call chain for hardware events
where the sample records get created some time after the event occurred.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-10-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Currently, callchains can be synthesized only for synthesized events. Add
an itrace option to synthesize callchains for regular events.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-9-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

An AUX area event must be the group leader when recording traces in
sample mode, but that does not produce the expected results from
'perf report' because it expects the leader to provide samples.

Rather than teach 'perf report' about AUX area sampling, un-group the
AUX area event during processing, making the 2nd event the leader.

Example:

 $ perf record -e '{intel_pt//u,branch-misses:u}' -c 1 uname
 Linux
 [ perf record: Woken up 1 times to write data ]
 [ perf record: Captured and wrote 0.080 MB perf.data ]

 Before:

 $ perf report

 Samples: 800  of events 'anon group { intel_pt//u, branch-misses:u }', Event count (approx.): 800
        Children              Self  Command  Shared Object     Symbol
     0.00%  47.50%     0.00%  47.50%  uname    libc-2.28.so      [.] _dl_addr
     0.00%  16.38%     0.00%  16.38%  uname    ld-2.28.so        [.] __GI___tunables_init
     0.00%  54.75%     0.00%   4.75%  uname    ld-2.28.so        [.] dl_main
     0.00%   3.12%     0.00%   3.12%  uname    ld-2.28.so        [.] _dl_map_object_from_fd
     0.00%   2.38%     0.00%   2.38%  uname    ld-2.28.so        [.] strcmp
     0.00%   2.25%     0.00%   2.25%  uname    ld-2.28.so        [.] _dl_check_map_versions
     0.00%   2.00%     0.00%   2.00%  uname    ld-2.28.so        [.] _dl_important_hwcaps
     0.00%   2.00%     0.00%   2.00%  uname    ld-2.28.so        [.] _dl_map_object_deps
     0.00%  51.50%     0.00%   1.50%  uname    ld-2.28.so        [.] _dl_sysdep_start
     0.00%   1.25%     0.00%   1.25%  uname    ld-2.28.so        [.] _dl_load_cache_lookup
     0.00%  51.12%     0.00%   1.12%  uname    ld-2.28.so        [.] _dl_start
     0.00%  50.88%     0.00%   1.12%  uname    ld-2.28.so        [.] do_lookup_x
     0.00%  50.62%     0.00%   1.00%  uname    ld-2.28.so        [.] _dl_lookup_symbol_x
     0.00%   1.00%     0.00%   1.00%  uname    ld-2.28.so        [.] _dl_map_object
     0.00%   1.00%     0.00%   1.00%  uname    ld-2.28.so        [.] _dl_next_ld_env_entry
     0.00%   0.88%     0.00%   0.88%  uname    ld-2.28.so        [.] _dl_cache_libcmp
     0.00%   0.88%     0.00%   0.88%  uname    ld-2.28.so        [.] _dl_new_object
     0.00%  50.88%     0.00%   0.88%  uname    ld-2.28.so        [.] _dl_relocate_object
     0.00%   0.62%     0.00%   0.62%  uname    ld-2.28.so        [.] _dl_init_paths
     0.00%   0.62%     0.00%   0.62%  uname    ld-2.28.so        [.] _dl_name_match_p
     0.00%   0.50%     0.00%   0.50%  uname    ld-2.28.so        [.] get_common_indeces.constprop.1
     0.00%   0.50%     0.00%   0.50%  uname    ld-2.28.so        [.] memmove
     0.00%   0.50%     0.00%   0.50%  uname    ld-2.28.so        [.] memset
     0.00%   0.50%     0.00%   0.50%  uname    ld-2.28.so        [.] open_verify.constprop.11
     0.00%   0.38%     0.00%   0.38%  uname    ld-2.28.so        [.] _dl_check_all_versions
     0.00%   0.38%     0.00%   0.38%  uname    ld-2.28.so        [.] _dl_find_dso_for_object
     0.00%   0.38%     0.00%   0.38%  uname    ld-2.28.so        [.] init_tls
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] __tunable_get_val
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] _dl_add_to_namespace_list
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] _dl_determine_tlsoffset
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] _dl_discover_osversion
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] calloc@plt
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] malloc
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] malloc@plt
     0.00%   0.25%     0.00%   0.25%  uname    libc-2.28.so      [.] _nl_load_locale_from_archive
     0.00%   0.25%     0.00%   0.25%  uname    [unknown]         [k] 0xffffffffa3a00010
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] __libc_scratch_buffer_set_array_size
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] _dl_allocate_tls_storage
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] _dl_catch_exception
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] _dl_setup_hash
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] _dl_sort_maps
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] _dl_sysdep_read_whole_file
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] access
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] calloc
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] mmap64
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] openaux
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] rtld_lock_default_lock_recursive
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] rtld_lock_default_unlock_recursive
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] strchr
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] strlen
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] 0x0000000000001080
     0.00%   0.12%     0.00%   0.12%  uname    libc-2.28.so      [.] __strchrnul_avx2
     0.00%   0.12%     0.00%   0.12%  uname    libc-2.28.so      [.] _nl_normalize_codeset
     0.00%   0.12%     0.00%   0.12%  uname    libc-2.28.so      [.] malloc
     0.00%   0.12%     0.00%   0.12%  uname    [unknown]         [k] 0xffffffffa3a011f0
     0.00%  50.00%     0.00%   0.00%  uname    ld-2.28.so        [.] _dl_start_user
     0.00%  50.00%     0.00%   0.00%  uname    [unknown]         [.] 0000000000000000

 After:

 Samples: 800  of event 'branch-misses:u', Event count (approx.): 800
  Children      Self  Command  Shared Object     Symbol
    54.75%     4.75%  uname    ld-2.28.so        [.] dl_main
    51.50%     1.50%  uname    ld-2.28.so        [.] _dl_sysdep_start
    51.12%     1.12%  uname    ld-2.28.so        [.] _dl_start
    50.88%     0.88%  uname    ld-2.28.so        [.] _dl_relocate_object
    50.88%     1.12%  uname    ld-2.28.so        [.] do_lookup_x
    50.62%     1.00%  uname    ld-2.28.so        [.] _dl_lookup_symbol_x
    50.00%     0.00%  uname    ld-2.28.so        [.] _dl_start_user
    50.00%     0.00%  uname    [unknown]         [.] 0000000000000000
    47.50%    47.50%  uname    libc-2.28.so      [.] _dl_addr
    16.38%    16.38%  uname    ld-2.28.so        [.] __GI___tunables_init
     3.12%     3.12%  uname    ld-2.28.so        [.] _dl_map_object_from_fd
     2.38%     2.38%  uname    ld-2.28.so        [.] strcmp
     2.25%     2.25%  uname    ld-2.28.so        [.] _dl_check_map_versions
     2.00%     2.00%  uname    ld-2.28.so        [.] _dl_important_hwcaps
     2.00%     2.00%  uname    ld-2.28.so        [.] _dl_map_object_deps
     1.25%     1.25%  uname    ld-2.28.so        [.] _dl_load_cache_lookup
     1.00%     1.00%  uname    ld-2.28.so        [.] _dl_map_object
     1.00%     1.00%  uname    ld-2.28.so        [.] _dl_next_ld_env_entry
     0.88%     0.88%  uname    ld-2.28.so        [.] _dl_cache_libcmp
     0.88%     0.88%  uname    ld-2.28.so        [.] _dl_new_object
     0.62%     0.62%  uname    ld-2.28.so        [.] _dl_init_paths
     0.62%     0.62%  uname    ld-2.28.so        [.] _dl_name_match_p
     0.50%     0.50%  uname    ld-2.28.so        [.] get_common_indeces.constprop.1
     0.50%     0.50%  uname    ld-2.28.so        [.] memmove
     0.50%     0.50%  uname    ld-2.28.so        [.] memset
     0.50%     0.50%  uname    ld-2.28.so        [.] open_verify.constprop.11
     0.38%     0.38%  uname    ld-2.28.so        [.] _dl_check_all_versions
     0.38%     0.38%  uname    ld-2.28.so        [.] _dl_find_dso_for_object
     0.38%     0.38%  uname    ld-2.28.so        [.] init_tls
     0.25%     0.25%  uname    ld-2.28.so        [.] __tunable_get_val
     0.25%     0.25%  uname    ld-2.28.so        [.] _dl_add_to_namespace_list
     0.25%     0.25%  uname    ld-2.28.so        [.] _dl_determine_tlsoffset
     0.25%     0.25%  uname    ld-2.28.so        [.] _dl_discover_osversion
     0.25%     0.25%  uname    ld-2.28.so        [.] calloc@plt
     0.25%     0.25%  uname    ld-2.28.so        [.] malloc
     0.25%     0.25%  uname    ld-2.28.so        [.] malloc@plt
     0.25%     0.25%  uname    libc-2.28.so      [.] _nl_load_locale_from_archive
     0.25%     0.25%  uname    [unknown]         [k] 0xffffffffa3a00010
     0.12%     0.12%  uname    ld-2.28.so        [.] __libc_scratch_buffer_set_array_size
     0.12%     0.12%  uname    ld-2.28.so        [.] _dl_allocate_tls_storage
     0.12%     0.12%  uname    ld-2.28.so        [.] _dl_catch_exception
     0.12%     0.12%  uname    ld-2.28.so        [.] _dl_setup_hash
     0.12%     0.12%  uname    ld-2.28.so        [.] _dl_sort_maps
     0.12%     0.12%  uname    ld-2.28.so        [.] _dl_sysdep_read_whole_file
     0.12%     0.12%  uname    ld-2.28.so        [.] access
     0.12%     0.12%  uname    ld-2.28.so        [.] calloc
     0.12%     0.12%  uname    ld-2.28.so        [.] mmap64
     0.12%     0.12%  uname    ld-2.28.so        [.] openaux
     0.12%     0.12%  uname    ld-2.28.so        [.] rtld_lock_default_lock_recursive
     0.12%     0.12%  uname    ld-2.28.so        [.] rtld_lock_default_unlock_recursive
     0.12%     0.12%  uname    ld-2.28.so        [.] strchr
     0.12%     0.12%  uname    ld-2.28.so        [.] strlen
     0.12%     0.12%  uname    ld-2.28.so        [.] 0x0000000000001080
     0.12%     0.12%  uname    libc-2.28.so      [.] __strchrnul_avx2
     0.12%     0.12%  uname    libc-2.28.so      [.] _nl_normalize_codeset
     0.12%     0.12%  uname    libc-2.28.so      [.] malloc
     0.12%     0.12%  uname    [unknown]         [k] 0xffffffffa3a011f0
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-8-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Implement ->evsel_is_auxtrace() callback.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Acked-by: NThomas Richter <tmricht@linux.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-7-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Implement ->evsel_is_auxtrace() callback.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Reviewed-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-6-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Implement ->evsel_is_auxtrace() callback.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Reviewed-by: NLeo Yan <leo.yan@linaro.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kim Phillips <kim.phillips@arm.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-5-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Implement ->evsel_is_auxtrace() callback.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-4-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Implement ->evsel_is_auxtrace() callback.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-3-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Add ->evsel_is_auxtrace() callback to identify if a selected event
is an AUX area event.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kim Phillips <kim.phillips@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-2-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This script works in tandem with d3-flame-graph to generate flame graphs
from perf. It supports two output formats: JSON and HTML (the default).
The HTML format will look for a standalone d3-flame-graph template file
in /usr/share/d3-flame-graph/d3-flamegraph-base.html and fill in the
collected stacks.

Usage:

    perf record -a -g -F 99 sleep 60
    perf script report flamegraph

Combined:

    perf script flamegraph -a -F 99 sleep 60

Committer testing:

Tested both with "PYTHON=python3" and with the default, that uses
python2-devel:

Complete set of instructions:

  $ mkdir /tmp/build/perf
  $ make PYTHON=python3 -C tools/perf O=/tmp/build/perf install-bin
  $ export PATH=~/bin:$PATH
  $ perf record -a -g -F 99 sleep 60
  $ perf script report flamegraph

Now go and open the generated flamegraph.html file in a browser.

At first this required building with PYTHON=python3, but after I
reported this Andreas was kind enough to send a patch making it work
with both python and python3.
Signed-off-by: NAndreas Gerstmayr <agerstmayr@redhat.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Brendan Gregg <bgregg@netflix.com>
Cc: Martin Spier <mspier@netflix.com>
Link: http://lore.kernel.org/lkml/20200320151355.66302-1-agerstmayr@redhat.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This patch refactors metricgroup__add_metric function where some part of
it move to function metricgroup__add_metric_param.  No logic change.
Signed-off-by: NKajol Jain <kjain@linux.ibm.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Joe Mario <jmario@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Mamatha Inamdar <mamatha4@linux.vnet.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lore.kernel.org/lkml/20200401203340.31402-4-kjain@linux.ibm.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Add the expr_scanner_ctx object to hold user data for the expr scanner.
Currently it holds only start_token, Kajol Jain will use it to hold 24x7
runtime param.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Joe Mario <jmario@redhat.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Mamatha Inamdar <mamatha4@linux.vnet.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lore.kernel.org/lkml/20200401203340.31402-3-kjain@linux.ibm.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Adding expr_ prefix for parse_ctx and parse_id, to straighten out the
expr* namespace.

There's no functional change.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Joe Mario <jmario@redhat.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Mamatha Inamdar <mamatha4@linux.vnet.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lore.kernel.org/lkml/20200401203340.31402-2-kjain@linux.ibm.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Reuse an existing char buffer to avoid two PATH_MAX sized char buffers.

Reduces stack frame sizes by 4kb.

perf_event__synthesize_mmap_events before 'sub $0x45b8,%rsp' after
'sub $0x35b8,%rsp'.

perf_event__get_comm_ids before 'sub $0x2028,%rsp' after
'sub $0x1028,%rsp'.

The performance impact of this change is negligible.
Signed-off-by: NIan Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrey Zhizhikin <andrey.z@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lore.kernel.org/lkml/20200402154357.107873-4-irogers@google.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The xxx_mountpoint() interface provided by fs.c finds mount points for
common pseudo filesystems. The first time xxx_mountpoint() is invoked,
it scans the mount table (/proc/mounts) looking for a match. If found,
it is cached. The price to scan /proc/mounts is paid once if the mount
is found.

When the mount point is not found, subsequent calls to xxx_mountpoint()
scan /proc/mounts over and over again.  There is no caching.

This causes a scaling issue in perf record with hugeltbfs__mountpoint().
The function is called for each process found in
synthesize__mmap_events().  If the machine has thousands of processes
and if the /proc/mounts has many entries this could cause major overhead
in perf record. We have observed multi-second slowdowns on some
configurations.

As an example on a laptop:

Before:

  $ sudo umount /dev/hugepages
  $ strace -e trace=openat -o /tmp/tt perf record -a ls
  $ fgrep mounts /tmp/tt
  285

After:

  $ sudo umount /dev/hugepages
  $ strace -e trace=openat -o /tmp/tt perf record -a ls
  $ fgrep mounts /tmp/tt
  1

One could argue that the non-caching in case the moint point is not
found is intentional. That way subsequent calls may discover a moint
point if the sysadmin mounts the filesystem. But the same argument could
be made against caching the mount point. It could be unmounted causing
errors.  It all depends on the intent of the interface. This patch
assumes it is expected to scan /proc/mounts once. The patch documents
the caching behavior in the fs.h header file.

An alternative would be to just fix perf record. But it would solve the
problem with hugetlbs__mountpoint() but there could be similar issues
(possibly down the line) with other xxx_mountpoint() calls in perf or
other tools.
Signed-off-by: NStephane Eranian <eranian@google.com>
Reviewed-by: NIan Rogers <irogers@google.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrey Zhizhikin <andrey.z@gmail.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lore.kernel.org/lkml/20200402154357.107873-3-irogers@google.comSigned-off-by: NIan Rogers <irogers@google.com>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Event synthesis may occur at the start or end (tail) of a perf command.
In system-wide mode it can scan every process in /proc, which may add
seconds of latency before event recording. Add a new benchmark that
times how long event synthesis takes with and without data synthesis.

An example execution looks like:

 $ perf bench internals synthesize
 # Running 'internals/synthesize' benchmark:
 Average synthesis took: 168.253800 usec
 Average data synthesis took: 208.104700 usec
Signed-off-by: NIan Rogers <irogers@google.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrey Zhizhikin <andrey.z@gmail.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lore.kernel.org/lkml/20200402154357.107873-2-irogers@google.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This simplifies the print functions for the following perf script
options:

	--show-task-events
	--show-namespace-events
	--show-cgroup-events
	--show-mmap-events
	--show-switch-events
	--show-lost-events
	--show-bpf-events

Example:
	# perf record --switch-events -a -e cycles -c 10000 sleep 1
 Before:
	# perf script --show-task-events --show-namespace-events --show-cgroup-events --show-mmap-events --show-switch-events --show-lost-events --show-bpf-events > out-before.txt
 After:
	# perf script --show-task-events --show-namespace-events --show-cgroup-events --show-mmap-events --show-switch-events --show-lost-events --show-bpf-events > out-after.txt
	# diff -s out-before.txt out-after.txt
	Files out-before.txt and out-after.tx are identical
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200402141548.21283-1-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Update the kernel.rst documentation file with the information related to
usage of CAP_PERFMON capability to secure performance monitoring and
observability operations in system.
Signed-off-by: NAlexey Budankov <alexey.budankov@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/84c32383-14a2-fa35-16b6-f9e59bd37240@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Update perf-security.rst documentation file with the information
related to usage of CAP_PERFMON capability to secure performance
monitoring and observability operations in system.

Committer notes:

While testing 'perf top' under cap_perfmon I noticed that it needs
some more capability and Alexey pointed out cap_ipc_lock, as needed by
this kernel chunk:

  kernel/events/core.c: 6101
       if ((locked > lock_limit) && perf_is_paranoid() &&
               !capable(CAP_IPC_LOCK)) {
               ret = -EPERM;
               goto unlock;
       }

So I added it to the documentation, and also mentioned that if the
libcap version doesn't yet supports 'cap_perfmon', its numeric value can
be used instead, i.e. if:

	# setcap "cap_perfmon,cap_ipc_lock,cap_sys_ptrace,cap_syslog=ep" perf

Fails, try:

	# setcap "38,cap_ipc_lock,cap_sys_ptrace,cap_syslog=ep" perf

I also added a paragraph stating that using an unpatched libcap will
fail the check for CAP_PERFMON, as it checks the cap number against a
maximum to see if it is valid, which makes it use as the default the
'cycles:u' event, even tho a cap_perfmon capable perf binary can get
kernel samples, to workaround that just use, e.g.:

  # perf top -e cycles
  # perf record -e cycles

And it will sample kernel and user modes.
Signed-off-by: NAlexey Budankov <alexey.budankov@linux.intel.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/17278551-9399-9ebe-d665-8827016a217d@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Open access to monitoring for CAP_PERFMON privileged process.  Providing
the access under CAP_PERFMON capability singly, without the rest of
CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials
and makes operation more secure.

CAP_PERFMON implements the principle of least privilege for performance
monitoring and observability operations (POSIX IEEE 1003.1e 2.2.2.39
principle of least privilege: A security design principle that states
that a process or program be granted only those privileges (e.g.,
capabilities) necessary to accomplish its legitimate function, and only
for the time that such privileges are actually required)

For backward compatibility reasons access to the monitoring remains open
for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage for
secure monitoring is discouraged with respect to CAP_PERFMON capability.
Signed-off-by: NAlexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: NJames Morris <jamorris@linux.microsoft.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/691f1096-b15f-9b12-50a0-c2b93918149e@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Open access to monitoring for CAP_PERFMON privileged process.  Providing
the access under CAP_PERFMON capability singly, without the rest of
CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials
and makes operation more secure.

CAP_PERFMON implements the principle of least privilege for performance
monitoring and observability operations (POSIX IEEE 1003.1e 2.2.2.39
principle of least privilege: A security design principle that states
that a process or program be granted only those privileges (e.g.,
capabilities) necessary to accomplish its legitimate function, and only
for the time that such privileges are actually required)

For backward compatibility reasons access to the monitoring remains open
for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage for
secure monitoring is discouraged with respect to CAP_PERFMON capability.
Signed-off-by: NAlexey Budankov <alexey.budankov@linux.intel.com>
Reviewed-by: NJames Morris <jamorris@linux.microsoft.com>
Acked-by: NWill Deacon <will@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/4ec1d6f7-548c-8d1c-f84a-cebeb9674e4e@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>