[PATCH v19 09/11] selftests: tracing: Add wprobe trigger testcases

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

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

Add testcases for checking wprobe triggers. This sets set_wprobe and
clear_wprobe triggers on fprobe event and static trace event to
monitor memory accesses within the trace-events-sample kernel module.
Also add a testcase for verifying wprobe triggers across CPU hotplug,
and a testcase for verifying wprobe trigger syntax error logging.

Link: https://lore.kernel.org/all/59637b96946653393a7ad3c7de094094796b39c2.1785067572.git.wangjinchao600@gmail.com/

Assisted-by: LLM
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v18:
 - Add "set_wprobe:<wprobe-event>":README to requires line in wprobe trigger
   tests so they are skipped if CONFIG_WPROBE_TRIGGERS is disabled.
 - Clear trace buffer after taking CPU offline in trigger-wprobe-hotplug.tc
   to avoid matching watchpoint events logged prior to offlining.
Changes in v17:
 - Add trigger-wprobe-hotplug.tc to verify wprobe triggers across
   CPU offline and online transitions.
Changes in v15:
 - Add explicit failure checks with fail helper in trigger-wprobe.tc.
 - Declare fprobe README requirement in trigger-wprobe.tc.
 - Add trigger file check to trigger-wprobe-syntax-errors.tc requires line.
 - Fix subject tag to tracing.
Changes in v14:
 - Update dummy wprobe event definition to use '-1' instead of '0'.
 - Add BTF argument dependency requirement in trigger-wprobe.tc.
 - Add delay before clear_trace in trigger-wprobe.tc to avoid race with
   clear_wprobe trigger execution.
Changes in v13:
 - Look up target function dynamically in trigger-wprobe-syntax-errors.tc.
 - Disable set_wprobe trigger before verifying clear_wprobe in
   trigger-wprobe.tc to avoid race condition with sample_timer_cb.
Changes in v12:
 - Add trigger-wprobe-syntax-errors.tc for verifying wprobe trigger syntax
   error logging.
 - Fix requires line in trigger-wprobe-syntax-errors.tc so test is not
   evaluated as unsupported prior to execution.
 - Define dfd=$arg1 fetcharg on testevent for trigger syntax checks.
Changes in v11:
 - Update testcase to use trace-events-sample kernel module instead of
   VFS file operations.
---
 tools/testing/selftests/ftrace/config              |    1 
 .../test.d/trigger/trigger-wprobe-hotplug.tc       |  153 ++++++++++++++++++++
 .../test.d/trigger/trigger-wprobe-syntax-errors.tc |   37 +++++
 .../ftrace/test.d/trigger/trigger-wprobe.tc        |  107 ++++++++++++++
 4 files changed, 298 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-hotplug.tc
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-syntax-errors.tc
 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 c2caea1ba1f5..7e07088464b6 100644
--- a/tools/testing/selftests/ftrace/config
+++ b/tools/testing/selftests/ftrace/config
@@ -34,3 +34,4 @@ 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-hotplug.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-hotplug.tc
new file mode 100644
index 000000000000..e7cfe5a4b259
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-hotplug.tc
@@ -0,0 +1,153 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test wprobe trigger across cpu hotplug
+# requires: dynamic_events "w[:[<group>/][<event>]] [r|w|rw]@<addr>[:<len>]":README "f[:[<group>/][<event>]] <func-name>[%return] [<args>]":README events/sched/sched_process_fork/trigger "[(structname[,field])]<argname>[->field[->field|.field...]]":README "set_wprobe:<wprobe-event>":README
+
+fail() { #msg
+  echo "$1"
+  exit_fail
+}
+
+if ! which nproc >/dev/null 2>&1 ; then
+  nproc() {
+    ls -d /sys/devices/system/cpu/cpu[0-9]* | wc -l
+  }
+fi
+
+NP=`nproc`
+if [ $NP -le 1 ] ; then
+  echo "We cannot test cpu hotplug in UP environment"
+  exit_unresolved
+fi
+
+# Find an online CPU that can be offlined
+for i in /sys/devices/system/cpu/cpu[1-9]*; do
+  if [ -f $i/online ] && [ "$(cat $i/online)" = "1" ]; then
+    cpu=$i
+    break
+  fi
+done
+
+if [ -z "$cpu" ]; then
+  echo "We cannot test cpu hotplug without a hotpluggable online cpu"
+  exit_unresolved
+fi
+
+rmmod trace-events-sample ||:
+if ! modprobe trace-events-sample ; then
+  echo "No trace-events sample module - please make CONFIG_SAMPLE_TRACE_EVENTS=m"
+  exit_unresolved
+fi
+
+cleanup_wprobe_triggers() {
+  [ -n "$cpu" ] && [ -f "$cpu/online" ] && echo 1 > $cpu/online || true
+  if [ -f events/fprobes/testevent/trigger ]; then
+    reset_trigger_file events/fprobes/testevent/trigger || true
+  fi
+  if [ -f events/sample-trace/foo_bar_with_fn/trigger ]; then
+    reset_trigger_file events/sample-trace/foo_bar_with_fn/trigger || true
+  fi
+  echo 0 > events/enable 2>/dev/null || true
+  echo > dynamic_events 2>/dev/null || true
+  sleep 1
+  rmmod trace-events-sample 2>/dev/null || true
+  return 0
+}
+
+trap cleanup_wprobe_triggers EXIT
+
+echo 0 > tracing_on
+
+# we will skip this test if fprobe is not supported.
+if ! grep -Fq "f[:[<group>/][<event>]] <func-name>[%return] [<args>]" README; then
+    echo "UNRESOLVED: fprobe is not supported"
+    exit_unresolved
+fi
+
+# we will skip this test if the target function does not exist.
+if ! grep -wq "sample_timer_cb" /proc/kallsyms; then
+    echo "UNRESOLVED: sample_timer_cb not found"
+    exit_unresolved
+fi
+
+:;: "Add a wprobe event used by trigger" ;:
+echo 'w:watch rw@-1:8 address=$addr value=$value' > dynamic_events
+
+:;: "Add events for triggering wprobe" ;:
+echo 'f:fprobes/testevent sample_timer_cb timer=t' >> dynamic_events
+
+:;: "Enable all events before setting triggers" ;:
+echo 1 > tracing_on
+echo 1 >> events/fprobes/testevent/enable
+echo 1 >> events/sample-trace/foo_bar_with_fn/enable
+
+:;: "Set set_wprobe trigger on testevent" ;:
+echo 'set_wprobe:watch:timer' >> events/fprobes/testevent/trigger
+if ! grep -q ^set_wprobe events/fprobes/testevent/trigger; then
+  fail "Failed to set set_wprobe trigger"
+fi
+
+:;: "Take target CPU offline" ;:
+echo 0 > $cpu/online
+sleep 1
+
+# Clear trace before waiting for events while CPU is offline
+clear_trace
+
+# Wait for sample_timer_cb to fire and set_wprobe trigger to activate while CPU is offline
+sleep 2
+
+:;: "Check set_wprobe trigger activated the watchpoint" ;:
+if ! grep -q watch trace; then
+  fail "Failed to trigger watchpoint while CPU is offline"
+fi
+
+:;: "Bring target CPU back online" ;:
+echo 1 > $cpu/online
+sleep 1
+
+# Clear trace and verify that watchpoint triggers after CPU is onlined
+clear_trace
+sleep 2
+
+:;: "Verify watchpoint triggers after CPU came back online" ;:
+if ! grep -q watch trace; then
+  fail "Failed to trigger watchpoint after CPU was onlined"
+fi
+
+:;: "Set clear_wprobe trigger on foo_bar_with_fn" ;:
+echo 'clear_wprobe:watch' >> events/sample-trace/foo_bar_with_fn/trigger
+if ! grep -q ^clear_wprobe events/sample-trace/foo_bar_with_fn/trigger; then
+  fail "Failed to set clear_wprobe trigger"
+fi
+
+# Disable set_wprobe to prevent sample_timer_cb from re-arming the watchpoint
+echo '!set_wprobe:watch:timer' >> events/fprobes/testevent/trigger
+
+# Wait for foo_bar_with_fn to fire and clear_wprobe trigger to deactivate watchpoint
+sleep 2
+
+# Clear trace and wait to ensure no new watchpoint events are generated
+clear_trace
+sleep 1
+
+:;: "Ensure clear_wprobe trigger deactivated the watchpoint" ;:
+if grep -q watch trace; then
+  fail "Failed to clear watchpoint"
+fi
+
+:;: "Remove wprobe triggers" ;:
+echo '!clear_wprobe:watch' >> events/sample-trace/foo_bar_with_fn/trigger
+if grep -q ^set_wprobe events/fprobes/testevent/trigger; then
+  fail "Failed to remove set_wprobe trigger"
+fi
+if grep -q ^clear_wprobe events/sample-trace/foo_bar_with_fn/trigger; then
+  fail "Failed to remove clear_wprobe trigger"
+fi
+
+:;: "Disable events and remove dynamic events" ;:
+echo 0 > events/enable
+echo > dynamic_events
+clear_trace
+
+exit 0
diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-syntax-errors.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-syntax-errors.tc
new file mode 100644
index 000000000000..87170a66e882
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-syntax-errors.tc
@@ -0,0 +1,37 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test wprobe trigger syntax errors
+# requires: dynamic_events error_log "w[:[<group>/][<event>]] [r|w|rw]@<addr>[:<len>]":README "f[:[<group>/][<event>]] <func-name>[%return] [<args>]":README events/sched/sched_process_fork/trigger "set_wprobe:<wprobe-event>":README
+
+check_error() { # command-with-error-pos-by-^
+    ftrace_errlog_check "wprobe_trigger" "$1" "events/fprobes/testevent/trigger"
+}
+
+TARGET_FUNC=$(grep -m 1 -E -w "[tT] (vfs_read|do_sys_openat2|do_sys_open)" /proc/kallsyms | awk '{print $3}')
+if [ -z "$TARGET_FUNC" ]; then
+    echo "UNRESOLVED: target function not found"
+    exit_unresolved
+fi
+
+# Add a dummy fprobe event to attach triggers to
+echo "f:fprobes/testevent $TARGET_FUNC dfd=\$arg1" > dynamic_events
+
+# Add a target wprobe event
+echo 'w:watch rw@-1:8' >> dynamic_events
+
+# Test errors on trigger syntax
+check_error 'set_wprobe:^non_exist_wprobe:dfd'	# WPROBE_NOT_FOUND
+check_error 'set_wprobe:^'				# WPROBE_NOT_FOUND
+check_error 'set_wprobe:watch^'				# WPROBE_NEED_FIELD
+check_error 'set_wprobe:watch:^non_exist_field'	# NO_EVENT_FIELD
+
+# Enable target wprobe event and test WPROBE_BUSY error
+echo 1 > events/wprobes/watch/enable
+check_error 'set_wprobe:^watch:dfd'			# WPROBE_BUSY
+echo 0 > events/wprobes/watch/enable
+
+# Cleanup
+echo '-:watch' >> dynamic_events
+echo '-:testevent' >> dynamic_events
+
+exit 0
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..a0565b80932c
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.tc
@@ -0,0 +1,107 @@
+#!/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 "f[:[<group>/][<event>]] <func-name>[%return] [<args>]":README events/sched/sched_process_fork/trigger "[(structname[,field])]<argname>[->field[->field|.field...]]":README "set_wprobe:<wprobe-event>":README
+
+fail() { #msg
+  echo "$1"
+  exit_fail
+}
+
+rmmod trace-events-sample ||:
+if ! modprobe trace-events-sample ; then
+  echo "No trace-events sample module - please make CONFIG_SAMPLE_TRACE_EVENTS=m"
+  exit_unresolved
+fi
+
+cleanup_wprobe_triggers() {
+  if [ -f events/fprobes/testevent/trigger ]; then
+    reset_trigger_file events/fprobes/testevent/trigger || true
+  fi
+  if [ -f events/sample-trace/foo_bar_with_fn/trigger ]; then
+    reset_trigger_file events/sample-trace/foo_bar_with_fn/trigger || true
+  fi
+  echo 0 > events/enable 2>/dev/null || true
+  echo > dynamic_events 2>/dev/null || true
+  sleep 1
+  rmmod trace-events-sample 2>/dev/null || true
+  return 0
+}
+
+trap cleanup_wprobe_triggers EXIT
+
+echo 0 > tracing_on
+
+# we will skip this test if fprobe is not supported.
+if ! grep -Fq "f[:[<group>/][<event>]] <func-name>[%return] [<args>]" README; then
+    echo "UNRESOLVED: fprobe is not supported"
+    exit_unresolved
+fi
+
+# we will skip this test if the target function does not exist.
+if ! grep -wq "sample_timer_cb" /proc/kallsyms; then
+    echo "UNRESOLVED: sample_timer_cb not found"
+    exit_unresolved
+fi
+
+:;: "Add a wprobe event used by trigger" ;:
+echo 'w:watch rw@-1:8 address=$addr value=$value' > dynamic_events
+
+:;: "Add events for triggering wprobe" ;:
+echo 'f:fprobes/testevent sample_timer_cb timer=t' >> dynamic_events
+
+:;: "Enable all events before setting triggers" ;:
+echo 1 > tracing_on
+echo 1 >> events/fprobes/testevent/enable
+echo 1 >> events/sample-trace/foo_bar_with_fn/enable
+
+:;: "Set set_wprobe trigger on testevent" ;:
+echo 'set_wprobe:watch:timer' >> events/fprobes/testevent/trigger
+if ! grep -q ^set_wprobe events/fprobes/testevent/trigger; then
+  fail "Failed to set set_wprobe trigger"
+fi
+
+# Wait for sample_timer_cb to fire and set_wprobe trigger to activate
+sleep 2
+
+:;: "Check set_wprobe trigger activated the watchpoint" ;:
+if ! grep -q watch trace; then
+  fail "Failed to trigger watchpoint"
+fi
+
+:;: "Set clear_wprobe trigger on foo_bar_with_fn" ;:
+echo 'clear_wprobe:watch' >> events/sample-trace/foo_bar_with_fn/trigger
+if ! grep -q ^clear_wprobe events/sample-trace/foo_bar_with_fn/trigger; then
+  fail "Failed to set clear_wprobe trigger"
+fi
+
+# Disable set_wprobe to prevent sample_timer_cb from re-arming the watchpoint
+echo '!set_wprobe:watch:timer' >> events/fprobes/testevent/trigger
+
+# Wait for foo_bar_with_fn to fire and clear_wprobe trigger to deactivate watchpoint
+sleep 2
+
+# Clear trace and wait to ensure no new watchpoint events are generated
+clear_trace
+sleep 1
+
+:;: "Ensure clear_wprobe trigger deactivated the watchpoint" ;:
+if grep -q watch trace; then
+  fail "Failed to clear watchpoint"
+fi
+
+:;: "Remove wprobe triggers" ;:
+echo '!clear_wprobe:watch' >> events/sample-trace/foo_bar_with_fn/trigger
+if grep -q ^set_wprobe events/fprobes/testevent/trigger; then
+  fail "Failed to remove set_wprobe trigger"
+fi
+if grep -q ^clear_wprobe events/sample-trace/foo_bar_with_fn/trigger; then
+  fail "Failed to remove clear_wprobe trigger"
+fi
+
+:;: "Disable events and remove dynamic events" ;:
+echo 0 > events/enable
+echo > dynamic_events
+clear_trace
+
+exit 0