bpftool: Only probe trace_vprintk feature in 'full' mode

Since commit 368cb0e7 ("bpftool: Make probes which emit dmesg
warnings optional"), some helpers aren't probed by bpftool unless
`full` arg is added to `bpftool feature probe`.

bpf_trace_vprintk can emit dmesg warnings when probed, so include it.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210917182911.2426606-7-davemarchevsky@fb.com

tools/bpf/bpftool/feature.c

@@ -624,6 +624,7 @@ probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
 		 */
 		switch (id) {
 		case BPF_FUNC_trace_printk:
+		case BPF_FUNC_trace_vprintk:
 		case BPF_FUNC_probe_write_user:
 			if (!full_mode)
 				continue;

tools/testing/selftests/bpf/test_bpftool.py

@@ -57,6 +57,11 @@ def default_iface(f):
         return f(*args, iface, **kwargs)
     return wrapper
 
+DMESG_EMITTING_HELPERS = [
+        "bpf_probe_write_user",
+        "bpf_trace_printk",
+        "bpf_trace_vprintk",
+    ]
 
 class TestBpftool(unittest.TestCase):
     @classmethod
@@ -67,10 +72,7 @@ class TestBpftool(unittest.TestCase):
 
     @default_iface
     def test_feature_dev_json(self, iface):
-        unexpected_helpers = [
-            "bpf_probe_write_user",
-            "bpf_trace_printk",
-        ]
+        unexpected_helpers = DMESG_EMITTING_HELPERS
         expected_keys = [
             "syscall_config",
             "program_types",
@@ -94,10 +96,7 @@ class TestBpftool(unittest.TestCase):
             bpftool_json(["feature", "probe"]),
             bpftool_json(["feature"]),
         ]
-        unexpected_helpers = [
-            "bpf_probe_write_user",
-            "bpf_trace_printk",
-        ]
+        unexpected_helpers = DMESG_EMITTING_HELPERS
         expected_keys = [
             "syscall_config",
             "system_config",
@@ -121,10 +120,7 @@ class TestBpftool(unittest.TestCase):
             bpftool_json(["feature", "probe", "kernel", "full"]),
             bpftool_json(["feature", "probe", "full"]),
         ]
-        expected_helpers = [
-            "bpf_probe_write_user",
-            "bpf_trace_printk",
-        ]
+        expected_helpers = DMESG_EMITTING_HELPERS
 
         for tc in test_cases:
             # Check if expected helpers are included at least once in any
@@ -157,7 +153,7 @@ class TestBpftool(unittest.TestCase):
                 not_full_set.add(helper)
 
         self.assertCountEqual(full_set - not_full_set,
-                                {"bpf_probe_write_user", "bpf_trace_printk"})
+                              set(DMESG_EMITTING_HELPERS))
         self.assertCountEqual(not_full_set - full_set, set())
 
     def test_feature_macros(self):