ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

12 files changed, 328 insertions, 0 deletions

diff --git a/tools/testing/selftests/verification/.gitignore b/tools/testing/selftests/verification/.gitignore
new file mode 100644
index 000000000..2659417cb
--- /dev/null
+++ b/tools/testing/selftests/verification/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+logs
diff --git a/tools/testing/selftests/verification/Makefile b/tools/testing/selftests/verification/Makefile
new file mode 100644
index 000000000..aa8790c22
--- /dev/null
+++ b/tools/testing/selftests/verification/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+all:
+
+TEST_PROGS := verificationtest-ktap
+TEST_FILES := test.d settings
+EXTRA_CLEAN := $(OUTPUT)/logs/*
+
+include ../lib.mk
diff --git a/tools/testing/selftests/verification/config b/tools/testing/selftests/verification/config
new file mode 100644
index 000000000..43072c1c3
--- /dev/null
+++ b/tools/testing/selftests/verification/config
@@ -0,0 +1 @@
+CONFIG_RV=y
diff --git a/tools/testing/selftests/verification/settings b/tools/testing/selftests/verification/settings
new file mode 100644
index 000000000..e7b941753
--- /dev/null
+++ b/tools/testing/selftests/verification/settings
@@ -0,0 +1 @@
+timeout=0
diff --git a/tools/testing/selftests/verification/test.d/functions b/tools/testing/selftests/verification/test.d/functions
new file mode 100644
index 000000000..ec36a092f
--- /dev/null
+++ b/tools/testing/selftests/verification/test.d/functions
@@ -0,0 +1,39 @@
+check_requires() { # Check required files, monitors and reactors
+	for i in "$@" ; do
+		p=${i%:program}
+		m=${i%:monitor}
+		r=${i%:reactor}
+		if [ $p != $i ]; then
+			if ! which $p ; then
+				echo "Required program $p is not found."
+				exit_unresolved
+			fi
+		elif [ $m != $i ]; then
+			if ! grep -wq $m available_monitors ; then
+				echo "Required monitor $m is not configured."
+				exit_unsupported
+			fi
+		elif [ $r != $i ]; then
+			if ! grep -wq $r available_reactors ; then
+				echo "Required reactor $r is not configured."
+				exit_unsupported
+			fi
+		elif [ ! -e $i ]; then
+			echo "Required feature interface $i doesn't exist."
+			exit_unsupported
+		fi
+	done
+}
+
+initialize_system() { # Reset RV to initial-state
+	echo > enabled_monitors
+	for m in monitors/*; do
+		echo nop > $m/reactors || true
+	done
+	echo 1 > monitoring_on
+	echo 1 > reacting_on || true
+}
+
+finish_system() {
+	initialize_system
+}
diff --git a/tools/testing/selftests/verification/test.d/rv_deadline.tc b/tools/testing/selftests/verification/test.d/rv_deadline.tc
new file mode 100644
index 000000000..fc95267db
--- /dev/null
+++ b/tools/testing/selftests/verification/test.d/rv_deadline.tc
@@ -0,0 +1,23 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+# description: Test deadline monitors trigger no reaction
+# requires: available_reactors deadline:monitor printk:reactor stress-ng:program
+
+load() { # returns true if there was a reaction
+	local lines_before
+	lines_before=$(dmesg | wc -l)
+	stress-ng --cpu 2 --sched deadline --sched-period 100000000 \
+		--sched-deadline 100000000 --sched-runtime 20000000 -t 5 &
+	stress-ng --cpu 2 --sched rr --sched-prio 50 --cyclic 1 \
+		--cyclic-policy rr --cyclic-prio 50 -t 5 &
+	wait
+	dmesg | tail -n +$((lines_before + 1)) | grep -q "rv: monitor [a-z]\+ does not allow event"
+}
+
+echo 1 > monitors/deadline/enable
+echo printk > monitors/deadline/reactors
+
+! load || false
+
+echo nop > monitors/deadline/reactors
+echo 0 > monitors/deadline/enable
diff --git a/tools/testing/selftests/verification/test.d/rv_monitor_enable_disable.tc b/tools/testing/selftests/verification/test.d/rv_monitor_enable_disable.tc
new file mode 100644
index 000000000..61e2c8b54
--- /dev/null
+++ b/tools/testing/selftests/verification/test.d/rv_monitor_enable_disable.tc
@@ -0,0 +1,75 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+# description: Test monitor enable/disable
+
+test_simple_monitor() {
+    local monitor="$1"
+    local prefix="$2" # nested monitors
+
+    echo 1 > "monitors/$prefix$monitor/enable"
+    grep -q "$monitor$" enabled_monitors
+
+    echo 0 > "monitors/$prefix$monitor/enable"
+    ! grep -q "$monitor$" enabled_monitors || false
+
+    echo "$monitor" >> enabled_monitors
+    grep -q 1 "monitors/$prefix$monitor/enable"
+
+    echo "!$monitor" >> enabled_monitors
+    grep -q 0 "monitors/$prefix$monitor/enable"
+}
+
+test_container_monitor() {
+    local monitor="$1"
+	local nested
+
+    echo 1 > "monitors/$monitor/enable"
+    grep -q "^$monitor$" enabled_monitors
+
+    for nested_dir in "monitors/$monitor"/*; do
+        [ -d "$nested_dir" ] || continue
+        nested=$(basename "$nested_dir")
+        grep -q "^$monitor:$nested$" enabled_monitors
+    done
+	test -n "$nested"
+
+    echo 0 > "monitors/$monitor/enable"
+    ! grep -q "^$monitor$" enabled_monitors || false
+
+    for nested_dir in "monitors/$monitor"/*; do
+        [ -d "$nested_dir" ] || continue
+        nested=$(basename "$nested_dir")
+        ! grep -q "^$monitor:$nested$" enabled_monitors || false
+    done
+
+    echo "$monitor" >> enabled_monitors
+    grep -q 1 "monitors/$monitor/enable"
+
+    for nested_dir in "monitors/$monitor"/*; do
+        [ -d "$nested_dir" ] || continue
+        nested=$(basename "$nested_dir")
+        grep -q "^$monitor:$nested$" enabled_monitors
+    done
+
+    echo "!$monitor" >> enabled_monitors
+    grep -q 0 "monitors/$monitor/enable"
+
+    for nested_dir in "monitors/$monitor"/*; do
+        [ -d "$nested_dir" ] || continue
+        nested=$(basename "$nested_dir")
+		test_simple_monitor "$nested" "$monitor/"
+    done
+}
+
+for monitor_dir in monitors/*; do
+    monitor=$(basename "$monitor_dir")
+
+    if find "$monitor_dir" -mindepth 1 -type d | grep -q .; then
+        test_container_monitor "$monitor"
+    else
+        test_simple_monitor "$monitor"
+    fi
+done
+
+! echo non_existent_monitor > enabled_monitors || false
+! grep -q "^non_existent_monitor$" enabled_monitors || false
diff --git a/tools/testing/selftests/verification/test.d/rv_monitor_reactor.tc b/tools/testing/selftests/verification/test.d/rv_monitor_reactor.tc
new file mode 100644
index 000000000..516a20971
--- /dev/null
+++ b/tools/testing/selftests/verification/test.d/rv_monitor_reactor.tc
@@ -0,0 +1,68 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+# description: Test monitor reactor setting
+# requires: available_reactors
+
+test_monitor_reactor() {
+    local monitor="$1"
+    local prefix="$2" # nested monitors
+
+    while read -r reactor; do
+        [ "$reactor" = nop ] && continue
+
+        echo "$reactor" > "monitors/$prefix$monitor/reactors"
+        grep -q "\\[$reactor\\]" "monitors/$prefix$monitor/reactors"
+    done < available_reactors
+
+    echo nop > "monitors/$prefix$monitor/reactors"
+    grep -q "\\[nop\\]" "monitors/$prefix$monitor/reactors"
+}
+
+test_container_monitor() {
+    local monitor="$1"
+	local nested
+
+    while read -r reactor; do
+        [ "$reactor" = nop ] && continue
+
+        echo "$reactor" > "monitors/$monitor/reactors"
+        grep -q "\\[$reactor\\]" "monitors/$monitor/reactors"
+
+        for nested_dir in "monitors/$monitor"/*; do
+            [ -d "$nested_dir" ] || continue
+            nested=$(basename "$nested_dir")
+            grep -q "\\[$reactor\\]" "monitors/$monitor/$nested/reactors"
+        done
+    done < available_reactors
+	test -n "$nested"
+
+    echo nop > "monitors/$monitor/reactors"
+    grep -q "\\[nop\\]" "monitors/$monitor/reactors"
+
+    for nested_dir in "monitors/$monitor"/*; do
+        [ -d "$nested_dir" ] || continue
+        nested=$(basename "$nested_dir")
+        grep -q "\\[nop\\]" "monitors/$monitor/$nested/reactors"
+    done
+
+    for nested_dir in "monitors/$monitor"/*; do
+        [ -d "$nested_dir" ] || continue
+        nested=$(basename "$nested_dir")
+        test_monitor_reactor "$nested" "$monitor/"
+    done
+}
+
+for monitor_dir in monitors/*; do
+    monitor=$(basename "$monitor_dir")
+
+    if find "$monitor_dir" -mindepth 1 -type d | grep -q .; then
+        test_container_monitor "$monitor"
+    else
+        test_monitor_reactor "$monitor"
+    fi
+done
+
+monitor=$(ls /sys/kernel/tracing/rv/monitors -1 | head -n 1)
+test -f "monitors/$monitor/reactors"
+! echo non_existent_reactor > "monitors/$monitor/reactors" || false
+! grep -q "\\[non_existent_reactor\\]" "monitors/$monitor/reactors" || false
diff --git a/tools/testing/selftests/verification/test.d/rv_monitors_available.tc b/tools/testing/selftests/verification/test.d/rv_monitors_available.tc
new file mode 100644
index 000000000..e6a4a1410
--- /dev/null
+++ b/tools/testing/selftests/verification/test.d/rv_monitors_available.tc
@@ -0,0 +1,18 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+# description: Check available monitors
+
+for monitor_dir in monitors/*; do
+    monitor=$(basename "$monitor_dir")
+
+    grep -q "^$monitor$" available_monitors
+    grep -q . "$monitor_dir"/desc
+
+    for nested_dir in "$monitor_dir"/*; do
+        [ -d "$nested_dir" ] || continue
+        nested=$(basename "$nested_dir")
+
+        grep -q "^$monitor:$nested$" available_monitors
+		grep -q . "$nested_dir"/desc
+    done
+done
diff --git a/tools/testing/selftests/verification/test.d/rv_stall.tc b/tools/testing/selftests/verification/test.d/rv_stall.tc
new file mode 100644
index 000000000..515a10263
--- /dev/null
+++ b/tools/testing/selftests/verification/test.d/rv_stall.tc
@@ -0,0 +1,33 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+# description: Test stall monitor
+# requires: available_reactors stall:monitor printk:reactor stress-ng:program
+
+THRESHOLD=/sys/module/stall/parameters/threshold_jiffies
+ORIG_THRESHOLD=$(cat $THRESHOLD)
+trap 'echo $ORIG_THRESHOLD > $THRESHOLD' EXIT
+
+load() { # returns true if there was a reaction
+	local lines_before cpu
+	cpu=$(($(nproc) - 1))
+	lines_before=$(dmesg | wc -l)
+	stress-ng --cpu 1 --taskset "$cpu" --sched rr --sched-prio 1 -t 3 &
+	stress-ng --cpu 5 --taskset "$cpu" -t 3 &
+	wait
+	dmesg | tail -n +$((lines_before + 1)) | grep -q "rv: monitor stall does not allow event"
+}
+
+echo 5000 > $THRESHOLD
+echo 1 > monitors/stall/enable
+echo printk > monitors/stall/reactors
+
+! load || false
+
+echo 0 > monitors/stall/enable
+echo 70 > $THRESHOLD
+echo 1 > monitors/stall/enable
+
+load
+
+echo nop > monitors/stall/reactors
+echo 0 > monitors/stall/enable
diff --git a/tools/testing/selftests/verification/test.d/rv_wwnr_printk.tc b/tools/testing/selftests/verification/test.d/rv_wwnr_printk.tc
new file mode 100644
index 000000000..17e1edfb3
--- /dev/null
+++ b/tools/testing/selftests/verification/test.d/rv_wwnr_printk.tc
@@ -0,0 +1,52 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+# description: Test wwnr monitor with printk reactor
+# requires: available_reactors wwnr:monitor printk:reactor stress-ng:program
+
+load() { # returns true if there was a reaction
+	local lines_before num load_pid ret
+	num=$((($(nproc) + 1) / 2))
+	lines_before=$(dmesg | wc -l)
+	stress-ng --cpu-sched "$num" --timer "$num" -t 5 -q &
+	load_pid=$!
+	timeout 5 dmesg -w | tail -n +$((lines_before + 1)) | \
+		grep -m 1 -q "rv: monitor wwnr does not allow event"
+	ret=$?
+	kill "$load_pid" || true
+	wait "$load_pid" || true
+	return $ret
+}
+
+# loads may flood the ringbuffer, wait for all pending printks (timeout at 2 minutes)
+wait_dmesg_flush() {
+	local last_before last_after
+	for _ in $(seq 400); do
+		last_before=$last_after
+		last_after=$(dmesg | grep "rv:" | tail -n 1 || true)
+		[ "$last_before" = "$last_after" ] && return 0
+		sleep .3
+	done
+	return 1
+}
+
+echo 1 > monitors/wwnr/enable
+echo printk > monitors/wwnr/reactors
+
+load
+
+echo 0 > monitoring_on
+wait_dmesg_flush
+
+! load || false
+echo 1 > monitoring_on
+
+load
+
+echo 0 > reacting_on
+wait_dmesg_flush
+
+! load || false
+echo 1 > reacting_on
+
+echo nop > monitors/wwnr/reactors
+echo 0 > monitors/wwnr/enable
diff --git a/tools/testing/selftests/verification/verificationtest-ktap b/tools/testing/selftests/verification/verificationtest-ktap
new file mode 100755
index 000000000..18f7fe324
--- /dev/null
+++ b/tools/testing/selftests/verification/verificationtest-ktap
@@ -0,0 +1,8 @@
+#!/bin/sh -e
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# ftracetest-ktap: Wrapper to integrate ftracetest with the kselftest runner
+#
+# Copyright (C) Arm Ltd., 2023
+
+../ftrace/ftracetest -K -v --rv ../verification