conftest: allow setting a minimum kernel version

For a while we've been beating around the bush by having a way to filter
out which vmcores we run tests against. But that doesn't help filtering
out kernel versions for live tests.

Most new functionality doesn't necessarily need to work on UEK4, so we
want it to be easy to skip tests below the minimum version.

Signed-off-by: Stephen Brennan <[email protected]>

Author: brenns10

tests/conftest.py

@@ -6,6 +6,7 @@
 from pathlib import Path
 from typing import List
 from typing import Optional
+from typing import Tuple
 
 import drgn
 import pytest
@@ -24,48 +25,14 @@
 CTF_FILE: Optional[str] = None
 
 CORE_DIR = Path.cwd() / "vmcores"
+KVER: Optional[KernelVersion] = None
+PROG: Optional[drgn.Program] = None
 
 
 @pytest.fixture(scope="session")
 def prog() -> drgn.Program:
-    p = drgn.Program()
-    if VMCORE:
-        p.set_core_dump(VMCORE)
-    elif os.geteuid() == 0:
-        p.set_kernel()
-    else:
-        from drgn.internal.sudohelper import open_via_sudo
-
-        p.set_core_dump(open_via_sudo("/proc/kcore", os.O_RDONLY))
-    if CTF:
-        try:
-            from drgn.helpers.linux.ctf import load_ctf
-
-            # CTF_FILE may be None here, in which case the default CTF file
-            # location is used (similar to below, where default DWARF debuginfo
-            # is loaded if we don't have a path).
-            load_ctf(p, path=CTF_FILE)
-            p.cache["using_ctf"] = True
-            # Mark in-tree modules as having debuginfo, so that the module API
-            # doesn't attempt to load debuginfo implicitly.
-            for module in p.modules():
-                if isinstance(module, MainModule) or module_is_in_tree(module):
-                    module.debug_file_status = ModuleFileStatus.DONT_NEED
-        except ModuleNotFoundError:
-            raise Exception("CTF is not supported, cannot run CTF test")
-    elif DEBUGINFO:
-        p.load_debug_info(DEBUGINFO)
-    else:
-        # Some UEK versions had mismatched vmlinux build IDs due to packaging
-        # issues. Most have been fixed, but for the remainder, set the main
-        # module's build ID to None manually, forcing drgn to skip verifying
-        # build IDs as it finds debuginfo.
-        ver = KernelVersion.parse(p["UTS_RELEASE"].string_().decode())
-        if has_vmlinux_build_id_mismatch(ver):
-            p.create_loaded_modules()
-            p.main_module().build_id = None
-        p.load_default_debug_info()
-    return p
+    assert PROG is not None
+    return PROG
 
 
 @pytest.fixture(scope="session")
@@ -96,7 +63,8 @@ def log_global_env_facts(prog, record_testsuite_property):
 
 @pytest.fixture(scope="session")
 def kver(prog):
-    return KernelVersion.parse(prog["UTS_RELEASE"].string_().decode())
+    assert KVER is not None
+    return KVER
 
 
 def pytest_addoption(parser):
@@ -154,6 +122,9 @@ def pytest_configure(config):
     config.addinivalue_line(
         "markers", "skip_vmcore(name): skip when debugging this core dump"
     )
+    config.addinivalue_line(
+        "markers", "kver_min(ver): specify minimum kernel version (x.y.z)"
+    )
 
     core_dir = config.getoption("vmcore_dir")
     if core_dir:
@@ -204,11 +175,54 @@ def pytest_configure(config):
     if CTF:
         print("TESTING WITH CTF")
 
+    global PROG
+    PROG = drgn.Program()
+    if VMCORE:
+        PROG.set_core_dump(VMCORE)
+    elif os.geteuid() == 0:
+        PROG.set_kernel()
+    else:
+        from drgn.internal.sudohelper import open_via_sudo
+
+        PROG.set_core_dump(open_via_sudo("/proc/kcore", os.O_RDONLY))
+
+    global KVER
+    KVER = KernelVersion.parse(PROG["UTS_RELEASE"].string_().decode())
+    if CTF:
+        try:
+            from drgn.helpers.linux.ctf import load_ctf
+
+            # CTF_FILE may be None here, in which case the default CTF file
+            # location is used (similar to below, where default DWARF debuginfo
+            # is loaded if we don't have a path).
+            load_ctf(PROG, path=CTF_FILE)
+            PROG.cache["using_ctf"] = True
+            # Mark in-tree modules as having debuginfo, so that the module API
+            # doesn't attempt to load debuginfo implicitly.
+            for module in PROG.modules():
+                if isinstance(module, MainModule) or module_is_in_tree(module):
+                    module.debug_file_status = ModuleFileStatus.DONT_NEED
+        except ModuleNotFoundError:
+            raise Exception("CTF is not supported, cannot run CTF test")
+    elif DEBUGINFO:
+        PROG.load_debug_info(DEBUGINFO)
+    else:
+        # Some UEK versions had mismatched vmlinux build IDs due to packaging
+        # issues. Most have been fixed, but for the remainder, set the main
+        # module's build ID to None manually, forcing drgn to skip verifying
+        # build IDs as it finds debuginfo.
+        if has_vmlinux_build_id_mismatch(KVER):
+            PROG.create_loaded_modules()
+            PROG.main_module().build_id = None
+        PROG.load_default_debug_info()
+
 
 def pytest_runtest_setup(item: pytest.Item):
     skip_live = False
     vmcore_pats = []
     vmcore_skip_pats = []
+    kver_min: Tuple[int, ...] = (0,)
+    assert KVER is not None
 
     for mark in item.iter_markers():
         if mark.name == "skip_live":
@@ -217,10 +231,17 @@ def pytest_runtest_setup(item: pytest.Item):
             vmcore_pats.append(mark.args[0])
         if mark.name == "skip_vmcore":
             vmcore_skip_pats.append(mark.args[0])
+        if mark.name == "kver_min":
+            kver_min = max(kver_min, tuple(map(int, mark.args[0].split("."))))
 
     if vmcore_pats and vmcore_skip_pats:
         raise ValueError("Can't mark a test both: vmcore() and skip_vmcore()")
 
+    if KVER.version_tuple < kver_min:
+        pytest.skip(
+            f"Skipped test (requires minimum kernel version: {kver_min})"
+        )
+
     if VMCORE:
         if vmcore_pats:
             if not any(fnmatch(VMCORE_NAME, p) for p in vmcore_pats):