On Tue, Mar 18, 2025 at 06:20:35PM -0300, Filipe Xavier wrote:

Add new ftrace helpers functions cleanup_tracing, trace_function and check_traced_functions.

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

tools/testing/selftests/livepatch/functions.sh | 49 ++++++++++++++++++++++++++ 1 file changed, 49 insertions(+)

diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh index 15601402dee6567837c2c49ba342eb357e410d18..dea9cc10a3f09662c57c2593cff49423302c8a5c 100644 --- a/tools/testing/selftests/livepatch/functions.sh +++ b/tools/testing/selftests/livepatch/functions.sh @@ -10,6 +10,7 @@ SYSFS_KERNEL_DIR="/sys/kernel" SYSFS_KLP_DIR="$SYSFS_KERNEL_DIR/livepatch" SYSFS_DEBUG_DIR="$SYSFS_KERNEL_DIR/debug" SYSFS_KPROBES_DIR="$SYSFS_DEBUG_DIR/kprobes" +SYSFS_TRACING_DIR="$SYSFS_DEBUG_DIR/tracing" # Kselftest framework requirement - SKIP code is 4 ksft_skip=4 @@ -62,6 +63,9 @@ 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_TRACING_DIR/tracing_on")
• CURRENT_TRACER=$(cat "$SYSFS_TRACING_DIR/current_tracer")
• FTRACE_FILTER=$(cat "$SYSFS_TRACING_DIR/set_ftrace_filter")

} function pop_config() { @@ -74,6 +78,17 @@ 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_TRACING_DIR/tracing_on"
  

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

• echo "$CURRENT_TRACER" > "$SYSFS_TRACING_DIR/current_tracer"
  

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

• echo "$FTRACE_FILTER" \
  

• 	| sed -e "/#### all functions enabled ####/d"
  

• 	> "$SYSFS_TRACING_DIR/set_ftrace_filter"
  

• fi

} function set_dynamic_debug() { @@ -352,3 +367,37 @@ function check_sysfs_value() { die "Unexpected value in $path: $expected_value vs. $value" fi }

+# cleanup_tracing() - stop and clean up function tracing +function cleanup_tracing() {

• echo 0 > "$SYSFS_TRACING_DIR/tracing_on"
• echo "" > "$SYSFS_TRACING_DIR/set_ftrace_filter"
• echo "nop" > "$SYSFS_TRACING_DIR/current_tracer"
• echo "" > "$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 "$function" > "$SYSFS_TRACING_DIR/set_ftrace_filter"
• echo 1 > "$SYSFS_TRACING_DIR/tracing_on"

+}

+# check_traced_functions(functions...) - check whether each function appeared in the trace log +# functions - list of functions to be checked +function check_traced_functions() {

• local function
• for function in "$@"; do

• if ! grep -q "$function" "$SYSFS_TRACING_DIR/trace" ; then
  

Small suggestion here: grep on "$function" may find partial string matches, like:

$ echo 'hamburger' | grep 'ham' hamburger

so it's probably safer to user --word-regexp to avoid longer function names inadvertently matching:

$ echo 'hamburger' | grep -w 'ham' $ echo 'ham' | grep -w 'ham' ham

Also, maybe also --fixed-strings for the extra paranoid? Off the top of my head, I don't think any C function characters are special regex (like $ ^ [ ] etc.) so it's probably safe w/o.

-- Joe

On Tue, Mar 18, 2025 at 06:20:36PM -0300, 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

tools/testing/selftests/livepatch/test-ftrace.sh | 34 ++++++++++++++++++++++++ 1 file changed, 34 insertions(+)

diff --git a/tools/testing/selftests/livepatch/test-ftrace.sh b/tools/testing/selftests/livepatch/test-ftrace.sh index fe14f248913acbec46fb6c0fec38a2fc84209d39..4937c74de0e4d34e4e692f20ee2bbe3cd6f5a232 100755 --- a/tools/testing/selftests/livepatch/test-ftrace.sh +++ b/tools/testing/selftests/livepatch/test-ftrace.sh @@ -61,4 +61,38 @@ livepatch: '$MOD_LIVEPATCH': unpatching complete % rmmod $MOD_LIVEPATCH" +# - verify livepatch can load +# - check if traces have a patched function +# - reset trace and unload livepatch

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

+FUNCTION_NAME="livepatch_cmdline_proc_show"

+load_lp $MOD_LIVEPATCH +trace_function "$FUNCTION_NAME"

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

• log "livepatch: ok"

+fi

+check_traced_functions "$FUNCTION_NAME"

+disable_lp $MOD_LIVEPATCH +unload_lp $MOD_LIVEPATCH

+check_result "% insmod test_modules/$MOD_LIVEPATCH.ko +livepatch: enabling patch '$MOD_LIVEPATCH' +livepatch: '$MOD_LIVEPATCH': initializing patching transition +livepatch: '$MOD_LIVEPATCH': starting patching transition +livepatch: '$MOD_LIVEPATCH': completing patching transition +livepatch: '$MOD_LIVEPATCH': patching complete +livepatch: ok +% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled

A few months ago, 637c730998b8 ("selftests: livepatch: rename KLP_SYSFS_DIR to SYSFS_KLP_DIR") tweaked the functions.sh::SYSFS_KLP_DIR and then updated all of the test-*.sh scripts to use the variable instead of the spelled out "/sys/kernel/livepatch" string.

So if there if there is another patchset version, s//sys/kernel/livepatch/$SYSFS_KLP_DIR/g

-- Joe