perf build: Properly guard libbpf includes

Including libbpf header files should be guarded by HAVE_LIBBPF_SUPPORT.
In bpf_counter.h, move the skeleton utilities under HAVE_BPF_SKEL.

Fixes: d6a735ef3277c45f ("perf bpf_counter: Move common functions to bpf_counter.h")
Reported-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Mike Leach <mike.leach@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.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/20230105172243.7238-1-mike.leach@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf bpf: Rename 'cpu' to 'cpu_map_idx'

Synchronize the caller in evsel with the called function.

Shorten 3 lines of code in bperf_read by using
perf_cpu_map__for_each_cpu().

This code is frequently using variables named cpu as cpu map indices,
which doesn't matter as all CPUs are in the CPU map. It is strange in
some cases the cpumap is used at all.

Committer notes:

Found when building with BUILD_BPF_SKEL=1:

Remove unused 'num_cpu' variable in bperf__read().

Make 'j' an 'int' as it is used in perf_cpu_map__for_each_cpu() to compare against an 'int'

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Riccardo Mancini <rickyman7@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Vineet Singh <vineet.singh@intel.com>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: zhengjun.xing@intel.com
Link: https://lore.kernel.org/r/20220105061351.120843-45-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf bpf_counter: Move common functions to bpf_counter.h

Some helper functions will be used for cgroup counting too. Move them
to a header file for sharing.

Committer notes:

Fix the build on older systems with:

- struct bpf_map_info map_info = {0};
+ struct bpf_map_info map_info = { .id = 0, };

This wasn't breaking the build in such systems as bpf_counter.c isn't
built due to:

tools/perf/util/Build:

perf-$(CONFIG_PERF_BPF_SKEL) += bpf_counter.o

The bpf_counter.h file on the other hand is included from places that
are built everywhere.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20210625071826.608504-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf stat: Introduce bpf_counter_ops->disable()

Introduce bpf_counter_ops->disable(), which is used stop counting the
event.

Committer notes:

Added a dummy bpf_counter__disable() to the python binding to avoid
having 'perf test python' failing.

bpf_counter isn't supported in the python binding.

Signed-off-by: Song Liu <song@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: kernel-team@fb.com
Link: https://lore.kernel.org/r/20210425214333.1090950-6-song@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf bpf: Minor whitespace cleanup.

Missed space after #include.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Song Liu <songliubraving@fb.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: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20210306080840.3785816-3-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf stat: Enable counting events for BPF programs

Introduce 'perf stat -b' option, which counts events for BPF programs, like:

[root@localhost ~]# ~/perf stat -e ref-cycles,cycles -b 254 -I 1000
1.487903822 115,200 ref-cycles
1.487903822 86,012 cycles
2.489147029 80,560 ref-cycles
2.489147029 73,784 cycles
3.490341825 60,720 ref-cycles
3.490341825 37,797 cycles
4.491540887 37,120 ref-cycles
4.491540887 31,963 cycles

The example above counts 'cycles' and 'ref-cycles' of BPF program of id
254. This is similar to bpftool-prog-profile command, but more
flexible.

'perf stat -b' creates per-cpu perf_event and loads fentry/fexit BPF
programs (monitor-progs) to the target BPF program (target-prog). The
monitor-progs read perf_event before and after the target-prog, and
aggregate the difference in a BPF map. Then the user space reads data
from these maps.

A new 'struct bpf_counter' is introduced to provide a common interface
that uses BPF programs/maps to count perf events.

Committer notes:

Removed all but bpf_counter.h includes from evsel.h, not needed at all.

Also BPF map lookups for PERCPU_ARRAYs need to have as its value receive
buffer passed to the kernel libbpf_num_possible_cpus() entries, not
evsel__nr_cpus(evsel), as the former uses
/sys/devices/system/cpu/possible while the later uses
/sys/devices/system/cpu/online, which may be less than the 'possible'
number making the bpf map lookup overwrite memory and cause hard to
debug memory corruption.

We need to continue using evsel__nr_cpus(evsel) when accessing the
perf_counts array tho, not to overwrite another are of memory :-)

Signed-off-by: Song Liu <songliubraving@fb.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/lkml/20210120163031.GU12699@kernel.org/
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-team@fb.com
Link: http://lore.kernel.org/lkml/20201229214214.3413833-4-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>