[PATCH v9 09/10] selftests: ftrace: Add wprobe trigger testcase

["Masami Hiramatsu (Google)" <mhiramat@kernel.org>]

From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Add a testcase for checking wprobe trigger. This sets set_wprobe and
clear_wprobe triggers on fprobe events to watch dentry access.
So this depends on both wprobe and fprobe.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
 Changes in v9:
  - Drop dentry cache after removing tempfile for on-disk
    filesystem.
 Changes in v8:
  - Use TMPDIR for making a test file.
  - Ensure the fprobe and target functions exists, if not, exit
    with UNRESOLVED (== skip).
 Changes in v7:
  - Add a newline at the end of file.(style fix)
  - Use dentry_kill instead of __dentry_kill.
 Changes in v5:
  - Enable CONFIG_WPROBE_TRIGGERS in the config for ftrace test.
 Changes in v3:
  - Newly added.
---
 tools/testing/selftests/ftrace/config              |    1 
 .../ftrace/test.d/trigger/trigger-wprobe.tc        |   70 ++++++++++++++++++++
 2 files changed, 71 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.tc

diff --git a/tools/testing/selftests/ftrace/config b/tools/testing/selftests/ftrace/config
index d2f503722020..ecdee77f360f 100644
--- a/tools/testing/selftests/ftrace/config
+++ b/tools/testing/selftests/ftrace/config
@@ -28,3 +28,4 @@ CONFIG_TRACER_SNAPSHOT=y
 CONFIG_UPROBES=y
 CONFIG_UPROBE_EVENTS=y
 CONFIG_WPROBE_EVENTS=y
+CONFIG_WPROBE_TRIGGERS=y
diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.tc
new file mode 100644
index 000000000000..0634259e2c65
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.tc
@@ -0,0 +1,70 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test wprobe trigger
+# requires: dynamic_events "w[:[<group>/][<event>]] [r|w|rw]@<addr>[:<len>]":README events/sched/sched_process_fork/trigger
+
+echo 0 > tracing_on
+rm -f $TMPDIR/hoge
+
+:;: "Add a wprobe event used by trigger" ;:
+echo 'w:watch rw@0:8 address=$addr value=+0($addr)' > dynamic_events
+
+# we will skip this test if fprobe is not supported.
+if ! grep -Fq "f[:[<group>/][<event>]] <func-name>[%return] [<args>]" README; then
+    echo "UNRESOLVED: fprobe is not supported"
+    exit_unresolved
+fi
+
+# we will skip this test if the target function does not exist.
+if ! grep -wq "do_truncate" /proc/kallsyms; then
+    echo "UNRESOLVED: do_truncate not found"
+    exit_unresolved
+fi
+if ! grep -wq "dentry_kill" /proc/kallsyms; then
+    echo "UNRESOLVED: dentry_kill not found"
+    exit_unresolved
+fi
+
+:;: "Add events for triggering wprobe" ;:
+echo 'f:truncate do_truncate dentry=$arg2' >> dynamic_events
+echo 'f:dentry_kill dentry_kill dentry=$arg1' >> dynamic_events
+
+:;: "Add wprobe triggers" ;:
+echo 'set_wprobe:watch:dentry' >> events/fprobes/truncate/trigger
+echo 'clear_wprobe:watch:dentry' >> events/fprobes/dentry_kill/trigger
+cat events/fprobes/truncate/trigger | grep ^set_wprobe
+cat events/fprobes/dentry_kill/trigger | grep ^clear_wprobe
+
+:;: "Ensure wprobe is still disabled" ;:
+cat events/wprobes/watch/enable | grep 0
+
+:;: "Enable events for triggers" ;:
+echo 1 >> events/fprobes/truncate/enable
+echo 1 >> events/fprobes/dentry_kill/enable
+
+:;: "Start test workload" ;:
+echo 1 >> tracing_on
+
+echo aaa > $TMPDIR/hoge
+echo bbb > $TMPDIR/hoge
+echo ccc > $TMPDIR/hoge
+rm $TMPDIR/hoge
+
+:;: "Drop dentry caches (for dentry_kill)" ;:
+# Use append (>>) to avoid calling do_truncate again.
+sync && echo 2 >> /proc/sys/vm/drop_caches
+
+:;: "Check trace results" ;:
+cat trace | grep watch
+
+
+:;: "Ensure wprobe becomes disabled again" ;:
+cat events/wprobes/watch/enable | grep 0
+
+:;: "Remove wprobe triggers" ;:
+echo '!set_wprobe:watch:dentry' >> events/fprobes/truncate/trigger
+echo '!clear_wprobe:watch' >> events/fprobes/dentry_kill/trigger
+! grep ^set_wprobe events/fprobes/truncate/trigger
+! grep ^clear_wprobe events/fprobes/dentry_kill/trigger
+
+exit 0