perf metric: Encode and use metric-id as qualifier

For a metric like IPC a group of events like {instructions,cycles}:W
would be formed.

If the events names were changed in parsing then the metric expression
parser would fail to find them.

This change makes the event encoding be something like:

  {instructions/metric-id=instructions/, cycles/metric-id=cycles/}

and then uses the evsel's stable metric-id value to locate the events.

This fixes the case that an event is restricted to user because of the
paranoia setting:

  $ echo 2 > /proc/sys/kernel/perf_event_paranoid
  $ perf stat -M IPC /bin/true
   Performance counter stats for '/bin/true':

             150,298      inst_retired.any:u        #      0.77 IPC
             187,095      cpu_clk_unhalted.thread:u

         0.002042731 seconds time elapsed

         0.000000000 seconds user
         0.002377000 seconds sys

Adding the metric-id as a qualifier has a complication in that
qualifiers will become embedded in qualifiers.

For example, msr/tsc/ could become msr/tsc,metric-id=msr/tsc// which
will fail parse-events.

To solve this problem the metric is encoded and decoded for the
metric-id with !<num> standing in for an encoded value.

Previously ! wasn't parsed.

With this msr/tsc/ becomes msr/tsc,metric-id=msr!3tsc!3/

The metric expression parser is changed so that @ isn't changed to /,
instead this is done when the ID is encoded for parse events.

metricgroup__add_metric_non_group() and metricgroup__add_metric_weak_group()
need to inject the metric-id qualifier, so to avoid repetition they are
merged into a single metricgroup__build_event_string with error codes
more rigorously checked.

stat-shadow's prepare_metric() uses the metric-id to match the metricgroup
code.

As "metric-id=..." is added to all events, it is adding during testing
with the fake PMU.

This complicates pmu_str_check code as PE_PMU_EVENT_FAKE won't match as
part of a configuration.

The testing fake PMU case is fixed so that if a known qualifier with an
! is parsed then it isn't reported as a fake PMU.

This is sufficient to pass all testing but it and the original mechanism
are somewhat brittle.

Signed-off-by: Ian Rogers <[email protected]>
Acked-by: Andi Kleen <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Antonov <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andrew Kilroy <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Changbin Du <[email protected]>
Cc: Denys Zagorui <[email protected]>
Cc: Fabian Hemmer <[email protected]>
Cc: Felix Fietkau <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jacob Keller <[email protected]>
Cc: Jiapeng Chong <[email protected]>
Cc: Jin Yao <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Joakim Zhang <[email protected]>
Cc: John Garry <[email protected]>
Cc: Kajol Jain <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Kees Kook <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Nicholas Fraser <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Paul Clarke <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Riccardo Mancini <[email protected]>
Cc: Sami Tolvanen <[email protected]>
Cc: ShihCheng Tu <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Sumanth Korikkar <[email protected]>
Cc: Thomas Richter <[email protected]>
Cc: Wan Jiabing <[email protected]>
Cc: Zhen Lei <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

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