Hi Filipe, first, thanks for the test. It is good. I just suggest a lot of clean up ;-)
On Sat 2025-01-11 15:42:27, Filipe Xavier wrote: > This new test makes sure that ftrace can trace a > function that was introduced by a livepatch. > --- > 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-v1-1-84880baef...@gmail.com > --- > 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") The $SYSFS_DEBUG_DIR/tracing directory is used many times. It would make sense to define: SYSFS_TRACING_DIR="$SYSFS_DEBUG_DIR/tracing" and use: TRACING_ON=$(cat "$SYSFS_TRACING_DIR/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 > "$SYSFS_DEBUG_DIR/tracing/set_ftrace_filter" My understanding is that this is handling the situation when the filter is: #### all functions enabled #### I was curious about the pattern *"#"*. The quotation looked pretty non-standard to me. It made me to read the bash documentation and the rules for extressions in [[ ]] looked quite complicated. I wonder if we could make this more for "dummies". The following seems to work: if [[ -n "$FTRACE_FILTER" ]]; then echo "$FTRACE_FILTER" | sed -e "/#### all functions enabled ####/d" > "$SYSFS_DEBUG_DIR/tracing/set_ftrace_filter" fi Note that the string "#### all functions enabled ####" is a very stable thing. It has never been modified since it was introduced by the commit 0c75a3ed633419d75d ("ftrace: state that all functions are enabled in set_ftrace_filter") in Feb 2009. The string is used also in ftrace selftests, see tools/testing/selftests/ftrace/test.d/ftrace/func_set_ftrace_file.tc > + 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" The above mentioned ftrace selftest shows that the behavior gets more complicated when "traceoff" is used: 1. The "traceoff" entries are not cleared by the above command. 2. The "traceoff" entries might cause that the tracing will stop before we finish this test. > +echo "function" > "$SYSFS_DEBUG_DIR/tracing/current_tracer" > +echo "" > "$TRACE_FILE" I suggest to change the ordering and make sure that nothing is running before we start: # Start with the clean up echo 0 > "$SYSFS_TRACING_DIR/tracing_on" echo '!*:traceoff' > $SYSFS_TRACING_DIR/set_ftrace_filter echo "" > "$SYSFS_TRACING_DIR/current_tracer" echo "" > $SYSFS_TRACING_DIR/trace # Setup and start our tracing echo "function" > "$SYSFS_TRACING_DIR/current_tracer" echo $FUNCTION_NAME > "$SYSFS_TRACING_DIR/set_ftrace_filter" echo 1 > "$SYSFS_TRACING_DIR/tracing_on" I suggest to this into helper functions which might be used by more tests: # cleanup_tracing() - stop and clean up function tracing function cleanup_tracing() { echo 0 > "$SYSFS_TRACING_DIR/tracing_on" echo '!*:traceoff' > $SYSFS_TRACING_DIR/set_ftrace_filter echo "" > "$SYSFS_TRACING_DIR/current_tracer" echo "" > $SYSFS_TRACING_DIR/trace } # trace_function(function) - start tracing of a function # function - to be traced function function trace_function() { local function="$1"; shift cleanup_tracing echo "function" > "$SYSFS_TRACING_DIR/current_tracer" echo "$functions" > $SYSFS_TRACING_DIR/set_ftrace_filter echo 1 > "$SYSFS_TRACING_DIR/tracing_on" } # check_traced_function(function) - check whether function appeared in trace log # function - to be traced function function check_trace_function() { local function="$1"; shift if ! grep -q "$function" $SYSFS_TRACING_DIR/trace" ; then die "Function ($function) did not appear in the trace" fi } As Marcos suggested, it would make sense to add the above mentioned helper functions in a separate patch. > + > +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=$? We could replace this with the above proposed check_traced_function "$FUNCTION_NAME" Also I would personally stop the tracing after this sub-test finishes. We might use the cleanup_tracing function here. cleanup_tracing > + > +disable_lp $MOD_LIVEPATCH > +unload_lp $MOD_LIVEPATCH > + > +if [ "$FOUND" -eq 1 ]; then > + echo -e "FAIL\n\n" > + die "livepatch kselftest(s) failed" > +fi As mentioned by Marcos, we should also print "ok" on success. I would personally use the "check_result" function here. It could catch non-expected entries in dmesg. > + > exit 0 Best Regards, Petr
