[llvm] [bolt][tests] Skip tests that use perf when perf counters are unavailable (PR #107892)

[Tom Stellard via llvm-commits]

https://github.com/tstellar created https://github.com/llvm/llvm-project/pull/107892

On the GitHub Action runners, perf always fails with the error below , so we need to skip the perf tests on platforms like this that have limited access to the perf counters.

```
Access to performance monitoring and observability operations is limited.
Consider adjusting /proc/sys/kernel/perf_event_paranoid setting to open
access to performance monitoring and observability operations for processes
without CAP_PERFMON, CAP_SYS_PTRACE or CAP_SYS_ADMIN Linux capability.
More information can be found at 'Perf events and tool security' document:
https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html
perf_event_paranoid setting is 4:
  -1: Allow use of (almost) all events by all users
      Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
>= 0: Disallow raw and ftrace function tracepoint access
>= 1: Disallow CPU event access
>= 2: Disallow kernel profiling
To make the adjusted perf_event_paranoid setting permanent preserve it
in /etc/sysctl.conf (e.g. kernel.perf_event_paranoid = <setting>)
```

>From a4256ad48b28e42521b780d6b4ce4c0225ff9901 Mon Sep 17 00:00:00 2001
From: Tom Stellard <tstellar at redhat.com>
Date: Sat, 7 Sep 2024 15:04:51 +0000
Subject: [PATCH] [bolt][tests] Skip tests that use perf when perf counters are
 unavailable

On the GitHub test runners, perf always the below error, so we need to
skip the perf tests on these platforms (and other platforms with the
same behavior):

```
Access to performance monitoring and observability operations is limited.
Consider adjusting /proc/sys/kernel/perf_event_paranoid setting to open
access to performance monitoring and observability operations for processes
without CAP_PERFMON, CAP_SYS_PTRACE or CAP_SYS_ADMIN Linux capability.
More information can be found at 'Perf events and tool security' document:
https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html
perf_event_paranoid setting is 4:
  -1: Allow use of (almost) all events by all users
      Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
>= 0: Disallow raw and ftrace function tracepoint access
>= 1: Disallow CPU event access
>= 2: Disallow kernel profiling
To make the adjusted perf_event_paranoid setting permanent preserve it
in /etc/sysctl.conf (e.g. kernel.perf_event_paranoid = <setting>)
```
---
 bolt/test/perf2bolt/lit.local.cfg | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/bolt/test/perf2bolt/lit.local.cfg b/bolt/test/perf2bolt/lit.local.cfg
index 4ee9ad08cc78a0..9f20f37c6a1d7d 100644
--- a/bolt/test/perf2bolt/lit.local.cfg
+++ b/bolt/test/perf2bolt/lit.local.cfg
@@ -1,4 +1,5 @@
 import shutil
+import subprocess
 
-if shutil.which("perf") is not None:
-    config.available_features.add("perf")
\ No newline at end of file
+if shutil.which("perf") is not None and subprocess.run(["perf", "record", "-e", "cycles:u", "-o", "/dev/null", "--", "perf"], capture_output=True).returncode == 0:
+    config.available_features.add("perf")