test: checks for tracepoint tests

For testing the USDT tracepoint API in the functional tests we
require:
 - that we are on a Linux system*
 - that Bitcoin Core is compiled with tracepoints
 - that bcc and the the Python bcc module [0] is installed
 - that we run the tests with the required permissions**
otherwise we skip the tests.

*:  We currently only support tracepoints on Linux. Tracepoints are
    not compiled on other platforms.
**: Currently, we check for root permissions via getuid == 0. It's
    unclear if it's even possible to run the tests a non-root user
    with e.g. CAP_BPF, CAP_PERFMON, and access to /sys/kernel/debug/
    tracing/. Anyone running these tests as root should carefully
    review them first and then run them in a disposable VM.

[0]: https://github.com/iovisor/bcc/blob/master/INSTALL.md

Author: 0xB10C

configure.ac

@@ -1363,6 +1363,7 @@ if test "$use_usdt" != "no"; then
     [AC_MSG_RESULT([no]); use_usdt=no;]
   )
 fi
+AM_CONDITIONAL([ENABLE_USDT_TRACEPOINTS], [test "$use_usdt" = "yes"])
 
 if test "$build_bitcoin_cli$build_bitcoin_tx$build_bitcoin_util$build_bitcoind$bitcoin_enable_qt$use_bench$use_tests" = "nonononononono"; then
   use_upnp=no

test/config.ini.in

@@ -25,3 +25,4 @@ RPCAUTH=@abs_top_srcdir@/share/rpcauth/rpcauth.py
 @ENABLE_ZMQ_TRUE@ENABLE_ZMQ=true
 @ENABLE_EXTERNAL_SIGNER_TRUE@ENABLE_EXTERNAL_SIGNER=true
 @ENABLE_SYSCALL_SANDBOX_TRUE@ENABLE_SYSCALL_SANDBOX=true
+@ENABLE_USDT_TRACEPOINTS_TRUE@ENABLE_USDT_TRACEPOINTS=true

test/functional/test_framework/test_framework.py

@@ -9,6 +9,7 @@
 import argparse
 import logging
 import os
+import platform
 import pdb
 import random
 import re
@@ -821,6 +822,29 @@ def skip_if_no_py3_zmq(self):
         except ImportError:
             raise SkipTest("python3-zmq module not available.")
 
+    def skip_if_no_python_bcc(self):
+        """Attempt to import the bcc package and skip the tests if the import fails."""
+        try:
+            import bcc  # type: ignore[import] # noqa: F401
+        except ImportError:
+            raise SkipTest("bcc python module not available")
+
+    def skip_if_no_bitcoind_tracepoints(self):
+        """Skip the running test if bitcoind has not been compiled with USDT tracepoint support."""
+        if not self.is_usdt_compiled():
+            raise SkipTest("bitcoind has not been built with USDT tracepoints enabled.")
+
+    def skip_if_no_bpf_permissions(self):
+        """Skip the running test if we don't have permissions to do BPF syscalls and load BPF maps."""
+        # check for 'root' permissions
+        if os.geteuid() != 0:
+            raise SkipTest("no permissions to use BPF (please review the tests carefully before running them with higher privileges)")
+
+    def skip_if_platform_not_linux(self):
+        """Skip the running test if we are not on a Linux platform"""
+        if platform.system() != "Linux":
+            raise SkipTest("not on a Linux system")
+
     def skip_if_no_bitcoind_zmq(self):
         """Skip the running test if bitcoind has not been compiled with zmq support."""
         if not self.is_zmq_compiled():
@@ -902,6 +926,10 @@ def is_zmq_compiled(self):
         """Checks whether the zmq module was compiled."""
         return self.config["components"].getboolean("ENABLE_ZMQ")
 
+    def is_usdt_compiled(self):
+        """Checks whether the USDT tracepoints were compiled."""
+        return self.config["components"].getboolean("ENABLE_USDT_TRACEPOINTS")
+
     def is_sqlite_compiled(self):
         """Checks whether the wallet module was compiled with Sqlite support."""
         return self.config["components"].getboolean("USE_SQLITE")