perf test: Extra verbosity and hypervisor skip for tpebs test

When not running as root and with higher perf event paranoia values
the perf record forked by TPEBS can fail to attach to the process. Skip
the test in these scenarios.

Intel TPEBS test skips on non-Intel CPUs. On Intel CPUs under a
hypervisor the cache-misses event may not be present or precise. Skip
the test under this condition.

Refactor the output code to be placed in a file so that on a signal
the file can be dumped. This was necessary to catch the issue above as
the failing perf record command would fail without output.

Signed-off-by: Ian Rogers <[e-mail]>
Tested-by: Thomas Falcon <[e-mail]>
Cc: Weilin Wang <[e-mail]>
Cc: James Clark <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/tests/shell/test_stat_intel_tpebs.sh

···
 # SPDX-License-Identifier: GPL-2.0
 
 set -e
-grep -q GenuineIntel /proc/cpuinfo || { echo Skipping non-Intel; exit 2; }
 
-# Use this event for testing because it should exist in all platforms
-event=cache-misses:R
+ParanoidAndNotRoot() {
+  [ "$(id -u)" != 0 ] && [ "$(cat /proc/sys/kernel/perf_event_paranoid)" -gt $1 ]
+}
 
-# Hybrid platforms output like "cpu_atom/cache-misses/R", rather than as above
-alt_name=/cache-misses/R
+if ! grep -q GenuineIntel /proc/cpuinfo
+then
+  echo "Skipping non-Intel"
+  exit 2
+fi
 
-# Without this cmd option, default value or zero is returned
-#echo "Testing without --record-tpebs"
-#result=$(perf stat -e "$event" true 2>&1)
-#[[ "$result" =~ $event || "$result" =~ $alt_name ]] || exit 1
+if ParanoidAndNotRoot 0
+then
+  echo "Skipping paranoid >0 and not root"
+  exit 2
+fi
 
-# In platforms that do not support TPEBS, it should execute without error.
-echo "Testing with --record-tpebs"
-result=$(perf stat -e "$event" --record-tpebs -a sleep 0.01 2>&1)
-[[ "$result" =~ "perf record" && "$result" =~ $event || "$result" =~ $alt_name ]] || exit 1
+stat_output=$(mktemp /tmp/__perf_stat_tpebs_output.XXXXX)
+
+cleanup() {
+  rm -rf "${stat_output}"
+  trap - EXIT TERM INT
+}
+
+trap_cleanup() {
+  echo "Unexpected signal in ${FUNCNAME[1]}"
+  cat "${stat_output}"
+  cleanup
+  exit 1
+}
+trap trap_cleanup EXIT TERM INT
+
+# Event to be used in tests
+event=cache-misses
+
+if ! perf record -e "${event}:p" -a -o /dev/null sleep 0.01 > "${stat_output}" 2>&1
+then
+  echo "Missing ${event} support"
+  cleanup
+  exit 2
+fi
+
+test_with_record_tpebs() {
+  echo "Testing with --record-tpebs"
+  if ! perf stat -e "${event}:R" --record-tpebs -a sleep 0.01 > "${stat_output}" 2>&1
+  then
+    echo "Testing with --record-tpebs [Failed perf stat]"
+    cat "${stat_output}"
+    exit 1
+  fi
+
+  # Expected output:
+  # $ perf stat --record-tpebs -e cache-misses:R -a sleep 0.01
+  # Events enabled
+  # [ perf record: Woken up 2 times to write data ]
+  # [ perf record: Captured and wrote 0.056 MB - ]
+  #
+  #  Performance counter stats for 'system wide':
+  #
+  #                  0      cache-misses:R
+  #
+  #        0.013963299 seconds time elapsed
+  if ! grep "perf record" "${stat_output}"
+  then
+    echo "Testing with --record-tpebs [Failed missing perf record]"
+    cat "${stat_output}"
+    exit 1
+  fi
+  if ! grep "${event}:R" "${stat_output}" && ! grep "/${event}/R" "${stat_output}"
+  then
+    echo "Testing with --record-tpebs [Failed missing event name]"
+    cat "${stat_output}"
+    exit 1
+  fi
+  echo "Testing with --record-tpebs [Success]"
+}
+
+test_with_record_tpebs
+cleanup
+exit 0