On Fri, 16 Feb 2024 15:26:26 +0530 Naveen N Rao naveen@kernel.org wrote:

Add a test to exercize cpu hotplug with the function tracer active to ensure that sensitive functions in idle path are excluded from being traced. This helps catch issues such as the one fixed by commit 4b3338aaa74d ("powerpc/ftrace: Fix stack teardown in ftrace_no_trace").

Signed-off-by: Naveen N Rao naveen@kernel.org Acked-by: Masami Hiramatsu (Google) mhiramat@kernel.org

Acked-by: Steven Rostedt (Google) rostedt@goodmis.org

Shuah, can you take this?

Thanks,

-- Steve

---

.../ftrace/test.d/ftrace/func_hotplug.tc | 42 +++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 tools/testing/selftests/ftrace/test.d/ftrace/func_hotplug.tc

diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/func_hotplug.tc b/tools/testing/selftests/ftrace/test.d/ftrace/func_hotplug.tc new file mode 100644 index 000000000000..ccfbfde3d942 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/ftrace/func_hotplug.tc @@ -0,0 +1,42 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0-or-later +# description: ftrace - function trace across cpu hotplug +# requires: function:tracer

+if ! which nproc ; then

• nproc() {
• ls -d /sys/devices/system/cpu/cpu[0-9]* | wc -l
• }

+fi

+NP=`nproc`

+if [ $NP -eq 1 ] ;then

• echo "We cannot test cpu hotplug in UP environment"
• exit_unresolved

+fi

+# Find online cpu +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 with a single cpu online"
• exit_unresolved

+fi

+echo 0 > tracing_on +echo > trace

+: "Set $(basename $cpu) offline/online with function tracer enabled" +echo function > current_tracer +echo 1 > tracing_on +(echo 0 > $cpu/online) +(echo "forked"; sleep 1) +(echo 1 > $cpu/online) +echo 0 > tracing_on +echo nop > current_tracer

base-commit: 130a83879954a9fed35cf4474d223b4fcfd479fa