perf test: Add mechanism for skipping attr tests on kernel versions

The first two version numbers are used since that is where the ABI
changes happen, so seems to be the most useful for now.

'Until' is exclusive and 'since' is inclusive so that the same version
number can be used to mark a point where the change comes into effect.

This allows keeping the tests in a state where new tests will also pass
on older kernels if the existence of a new feature isn't explicitly
broadcast by the kernel. For example extended user regs are currently
discovered by trial and error calls to perf_event_open.

Signed-off-by: James Clark <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: [e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/attr.py

···
 import sys
 import glob
 import optparse
+import platform
 import tempfile
 import logging
 import re
···
             if not data_equal(self[t], other[t]):
                 log.warning("expected %s=%s, got %s" % (t, self[t], other[t]))
 
+def parse_version(version):
+    if not version:
+        return None
+    return [int(v) for v in version.split(".")[0:2]]
+
 # Test file description needs to have following sections:
 # [config]
 #   - just single instance in file
···
 #                 negates it.
 #     'auxv'    - Truthy statement that is evaled in the scope of the auxv map. When false,
 #                 the test is skipped. For example 'auxv["AT_HWCAP"] == 10'. (optional)
-#
+#     'kernel_since' - Inclusive kernel version from which the test will start running. Only the
+#                      first two values are supported, for example "6.1" (optional)
+#     'kernel_until' - Exclusive kernel version from which the test will stop running. (optional)
 # [eventX:base]
 #   - one or multiple instances in file
 #   - expected values assignments
···
             self.arch  = ''
 
         self.auxv = parser.get('config', 'auxv', fallback=None)
+        self.kernel_since = parse_version(parser.get('config', 'kernel_since', fallback=None))
+        self.kernel_until = parse_version(parser.get('config', 'kernel_until', fallback=None))
         self.expect   = {}
         self.result   = {}
         log.debug("  loading expected events");
···
             return False
         else:
             return True
+
+    def skip_test_kernel_since(self):
+        if not self.kernel_since:
+            return False
+        return not self.kernel_since <= parse_version(platform.release())
+
+    def skip_test_kernel_until(self):
+        if not self.kernel_until:
+            return False
+        return not parse_version(platform.release()) < self.kernel_until
 
     def skip_test_auxv(self):
         def new_auxv(a, pattern):
···
 
         if self.skip_test_auxv():
             raise Notest(self, "auxv skip")
+
+        if self.skip_test_kernel_since():
+            raise Notest(self, "old kernel skip")
+
+        if self.skip_test_kernel_until():
+            raise Notest(self, "new kernel skip")
 
         cmd = "PERF_TEST_ATTR=%s %s %s -o %s/perf.data %s" % (tempdir,
               self.perf, self.command, tempdir, self.args)