Re: [PATCH v2] selftests: livepatch: test if ftrace can trace a livepatched function

On 1/11/25 3:42 PM, Filipe Xavier wrote:

This new test makes sure that ftrace can trace a function that was introduced by a livepatch.

Signed-off-by: Filipe Xavier felipeaggger@gmail.com

Changes in v2:

• functions.sh: added reset tracing on push and pop_config.
• test-ftrace.sh: enabled tracing_on before test init.
• nitpick: added double quotations on filenames and fixed some wording.
• Link to v1: https://lore.kernel.org/r/20250102-ftrace-selftest-livepatch-v1-1-84880baefc...

---

tools/testing/selftests/livepatch/functions.sh | 14 ++++++++++ tools/testing/selftests/livepatch/test-ftrace.sh | 33 ++++++++++++++++++++++++ 2 files changed, 47 insertions(+)

diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh index e5d06fb402335d85959bafe099087effc6ddce12..e6c13514002dae5f8d7461f90b8241ab43024ea4 100644 --- a/tools/testing/selftests/livepatch/functions.sh +++ b/tools/testing/selftests/livepatch/functions.sh @@ -62,6 +62,9 @@ function push_config() { awk -F'[: ]' '{print "file " $1 " line " $2 " " $4}') FTRACE_ENABLED=$(sysctl --values kernel.ftrace_enabled) KPROBE_ENABLED=$(cat "$SYSFS_KPROBES_DIR/enabled")

• TRACING_ON=$(cat "$SYSFS_DEBUG_DIR/tracing/tracing_on")
• CURRENT_TRACER=$(cat "$SYSFS_DEBUG_DIR/tracing/current_tracer")
• FTRACE_FILTER=$(cat "$SYSFS_DEBUG_DIR/tracing/set_ftrace_filter") }

function pop_config() { @@ -74,6 +77,17 @@ function pop_config() { if [[ -n "$KPROBE_ENABLED" ]]; then echo "$KPROBE_ENABLED" > "$SYSFS_KPROBES_DIR/enabled" fi

• if [[ -n "$TRACING_ON" ]]; then

• echo "$TRACING_ON" > "$SYSFS_DEBUG_DIR/tracing/tracing_on"
  

• fi
• if [[ -n "$CURRENT_TRACER" ]]; then

• echo "$CURRENT_TRACER" > "$SYSFS_DEBUG_DIR/tracing/current_tracer"
  

• fi
• if [[ "$FTRACE_FILTER" == *"#"* ]]; then

• echo > "$SYSFS_DEBUG_DIR/tracing/set_ftrace_filter"
  

• elif [[ -n "$FTRACE_FILTER" ]]; then

• echo "$FTRACE_FILTER" > "$SYSFS_DEBUG_DIR/tracing/set_ftrace_filter"
  

• fi }

function set_dynamic_debug() { diff --git a/tools/testing/selftests/livepatch/test-ftrace.sh b/tools/testing/selftests/livepatch/test-ftrace.sh index fe14f248913acbec46fb6c0fec38a2fc84209d39..66af5d726c52e48e5177804e182b4ff31784d5ac 100755 --- a/tools/testing/selftests/livepatch/test-ftrace.sh +++ b/tools/testing/selftests/livepatch/test-ftrace.sh @@ -61,4 +61,37 @@ livepatch: '$MOD_LIVEPATCH': unpatching complete % rmmod $MOD_LIVEPATCH" +# - verify livepatch can load +# - check if traces have a patched function +# - unload livepatch and reset trace

+start_test "trace livepatched function and check that the live patch remains in effect"

+TRACE_FILE="$SYSFS_DEBUG_DIR/tracing/trace" +FUNCTION_NAME="livepatch_cmdline_proc_show"

+load_lp $MOD_LIVEPATCH

+echo 1 > "$SYSFS_DEBUG_DIR/tracing/tracing_on" +echo $FUNCTION_NAME > "$SYSFS_DEBUG_DIR/tracing/set_ftrace_filter" +echo "function" > "$SYSFS_DEBUG_DIR/tracing/current_tracer" +echo "" > "$TRACE_FILE"

+if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" ]] ; then

• echo -e "FAIL\n\n"
• die "livepatch kselftest(s) failed"

+fi

+grep -q $FUNCTION_NAME "$TRACE_FILE" +FOUND=$?

+disable_lp $MOD_LIVEPATCH +unload_lp $MOD_LIVEPATCH

+if [ "$FOUND" -eq 1 ]; then

• echo -e "FAIL\n\n"
• die "livepatch kselftest(s) failed"

+fi

• exit 0

---

base-commit: fc033cf25e612e840e545f8d5ad2edd6ba613ed5 change-id: 20250101-ftrace-selftest-livepatch-161fb77dbed8

Best regards,

Hi Folks, sorry for the delay... thanks everyone for the feedback's.

I applied almost all the requested adjustments, except this one:

echo '!*:traceoff' > "$SYSFS_TRACING_DIR/set_ftrace_filter"

causes this error:  "echo: write error: no such device"

echo "" > "$SYSFS_TRACING_DIR/current_tracer"

causes this error:  "echo: write error: invalid argument"

I sent a new patchSet(splited) to the list.

Cheers,

Filipe Xavier