[PATCH v5 0/3] selftests: livepatch: test livepatching a kprobed function

[PATCH v5 0/3] selftests: livepatch: test livepatching a kprobed function

[Michael Vetter]

Thanks for all the reviews.

V5:
Replace /sys/kernel/livepatch also in other/already existing tests.
Improve commit message of 3rd patch.

V4:
Use variable for /sys/kernel/debug.
Be consistent with "" around variables.
Fix path in commit message to /sys/kernel/debug/kprobes/enabled.

V3:
Save and restore kprobe state also when test fails, by integrating it
into setup_config() and cleanup().
Rename SYSFS variables in a more logical way.
Sort test modules in alphabetical order.
Rename module description.

V2:
Save and restore kprobe state.

Michael Vetter (3):
  selftests: livepatch: rename KLP_SYSFS_DIR to SYSFS_KLP_DIR
  selftests: livepatch: save and restore kprobe state
  selftests: livepatch: test livepatching a kprobed function

 tools/testing/selftests/livepatch/Makefile    |  3 +-
 .../testing/selftests/livepatch/functions.sh  | 29 +++++----
 .../selftests/livepatch/test-callbacks.sh     | 24 +++----
 .../selftests/livepatch/test-ftrace.sh        |  2 +-
 .../selftests/livepatch/test-kprobe.sh        | 62 +++++++++++++++++++
 .../selftests/livepatch/test-livepatch.sh     | 12 ++--
 .../testing/selftests/livepatch/test-state.sh |  8 +--
 .../selftests/livepatch/test-syscall.sh       |  2 +-
 .../testing/selftests/livepatch/test-sysfs.sh |  8 +--
 .../selftests/livepatch/test_modules/Makefile |  3 +-
 .../livepatch/test_modules/test_klp_kprobe.c  | 38 ++++++++++++
 11 files changed, 150 insertions(+), 41 deletions(-)
 create mode 100755 tools/testing/selftests/livepatch/test-kprobe.sh
 create mode 100644 tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c

-- 
2.47.0

[PATCH v5 1/3] selftests: livepatch: rename KLP_SYSFS_DIR to SYSFS_KLP_DIR

[Michael Vetter]

This naming makes more sense according to the directory structure.
Especially when we later add more paths.

Addtionally replace `/sys/kernel/livepatch` with `$SYSFS_KLP_DIR` in
the livepatch test files.

Signed-off-by: Michael Vetter <mvetter@suse.com>
---
 .../testing/selftests/livepatch/functions.sh  | 16 ++++++-------
 .../selftests/livepatch/test-callbacks.sh     | 24 +++++++++----------
 .../selftests/livepatch/test-ftrace.sh        |  2 +-
 .../selftests/livepatch/test-livepatch.sh     | 12 +++++-----
 .../testing/selftests/livepatch/test-state.sh |  8 +++----
 .../selftests/livepatch/test-syscall.sh       |  2 +-
 .../testing/selftests/livepatch/test-sysfs.sh |  8 +++----
 7 files changed, 36 insertions(+), 36 deletions(-)

diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
index fc4c6a016d38..e0e7f8db894c 100644
--- a/tools/testing/selftests/livepatch/functions.sh
+++ b/tools/testing/selftests/livepatch/functions.sh
@@ -6,7 +6,7 @@
 
 MAX_RETRIES=600
 RETRY_INTERVAL=".1"	# seconds
-KLP_SYSFS_DIR="/sys/kernel/livepatch"
+SYSFS_KLP_DIR="/sys/kernel/livepatch"
 
 # Kselftest framework requirement - SKIP code is 4
 ksft_skip=4
@@ -183,7 +183,7 @@ function load_lp_nowait() {
 	__load_mod "$mod" "$@"
 
 	# Wait for livepatch in sysfs ...
-	loop_until '[[ -e "/sys/kernel/livepatch/$mod" ]]' ||
+	loop_until '[[ -e "$SYSFS_KLP_DIR/$mod" ]]' ||
 		die "failed to load module $mod (sysfs)"
 }
 
@@ -196,7 +196,7 @@ function load_lp() {
 	load_lp_nowait "$mod" "$@"
 
 	# Wait until the transition finishes ...
-	loop_until 'grep -q '^0$' /sys/kernel/livepatch/$mod/transition' ||
+	loop_until 'grep -q '^0$' $SYSFS_KLP_DIR/$mod/transition' ||
 		die "failed to complete transition"
 }
 
@@ -246,12 +246,12 @@ function unload_lp() {
 function disable_lp() {
 	local mod="$1"
 
-	log "% echo 0 > /sys/kernel/livepatch/$mod/enabled"
-	echo 0 > /sys/kernel/livepatch/"$mod"/enabled
+	log "% echo 0 > $SYSFS_KLP_DIR/$mod/enabled"
+	echo 0 > "$SYSFS_KLP_DIR"/mod"/enabled
 
 	# Wait until the transition finishes and the livepatch gets
 	# removed from sysfs...
-	loop_until '[[ ! -e "/sys/kernel/livepatch/$mod" ]]' ||
+	loop_until '[[ ! -e "$SYSFS_KLP_DIR/$mod" ]]' ||
 		die "failed to disable livepatch $mod"
 }
 
@@ -322,7 +322,7 @@ function check_sysfs_rights() {
 	local rel_path="$1"; shift
 	local expected_rights="$1"; shift
 
-	local path="$KLP_SYSFS_DIR/$mod/$rel_path"
+	local path="$SYSFS_KLP_DIR/$mod/$rel_path"
 	local rights=$(/bin/stat --format '%A' "$path")
 	if test "$rights" != "$expected_rights" ; then
 		die "Unexpected access rights of $path: $expected_rights vs. $rights"
@@ -338,7 +338,7 @@ function check_sysfs_value() {
 	local rel_path="$1"; shift
 	local expected_value="$1"; shift
 
-	local path="$KLP_SYSFS_DIR/$mod/$rel_path"
+	local path="$SYSFS_KLP_DIR/$mod/$rel_path"
 	local value=`cat $path`
 	if test "$value" != "$expected_value" ; then
 		die "Unexpected value in $path: $expected_value vs. $value"
diff --git a/tools/testing/selftests/livepatch/test-callbacks.sh b/tools/testing/selftests/livepatch/test-callbacks.sh
index 32b150e25b10..37bbc3fb2780 100755
--- a/tools/testing/selftests/livepatch/test-callbacks.sh
+++ b/tools/testing/selftests/livepatch/test-callbacks.sh
@@ -46,7 +46,7 @@ livepatch: '$MOD_LIVEPATCH': completing patching transition
 $MOD_LIVEPATCH: post_patch_callback: vmlinux
 $MOD_LIVEPATCH: post_patch_callback: $MOD_TARGET -> [MODULE_STATE_LIVE] Normal state
 livepatch: '$MOD_LIVEPATCH': patching complete
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 $MOD_LIVEPATCH: pre_unpatch_callback: vmlinux
 $MOD_LIVEPATCH: pre_unpatch_callback: $MOD_TARGET -> [MODULE_STATE_LIVE] Normal state
@@ -94,7 +94,7 @@ livepatch: applying patch '$MOD_LIVEPATCH' to loading module '$MOD_TARGET'
 $MOD_LIVEPATCH: pre_patch_callback: $MOD_TARGET -> [MODULE_STATE_COMING] Full formed, running module_init
 $MOD_LIVEPATCH: post_patch_callback: $MOD_TARGET -> [MODULE_STATE_COMING] Full formed, running module_init
 $MOD_TARGET: ${MOD_TARGET}_init
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 $MOD_LIVEPATCH: pre_unpatch_callback: vmlinux
 $MOD_LIVEPATCH: pre_unpatch_callback: $MOD_TARGET -> [MODULE_STATE_LIVE] Normal state
@@ -146,7 +146,7 @@ $MOD_TARGET: ${MOD_TARGET}_exit
 $MOD_LIVEPATCH: pre_unpatch_callback: $MOD_TARGET -> [MODULE_STATE_GOING] Going away
 livepatch: reverting patch '$MOD_LIVEPATCH' on unloading module '$MOD_TARGET'
 $MOD_LIVEPATCH: post_unpatch_callback: $MOD_TARGET -> [MODULE_STATE_GOING] Going away
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 $MOD_LIVEPATCH: pre_unpatch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH': starting unpatching transition
@@ -195,7 +195,7 @@ $MOD_TARGET: ${MOD_TARGET}_exit
 $MOD_LIVEPATCH: pre_unpatch_callback: $MOD_TARGET -> [MODULE_STATE_GOING] Going away
 livepatch: reverting patch '$MOD_LIVEPATCH' on unloading module '$MOD_TARGET'
 $MOD_LIVEPATCH: post_unpatch_callback: $MOD_TARGET -> [MODULE_STATE_GOING] Going away
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 $MOD_LIVEPATCH: pre_unpatch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH': starting unpatching transition
@@ -227,7 +227,7 @@ livepatch: '$MOD_LIVEPATCH': starting patching transition
 livepatch: '$MOD_LIVEPATCH': completing patching transition
 $MOD_LIVEPATCH: post_patch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH': patching complete
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 $MOD_LIVEPATCH: pre_unpatch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH': starting unpatching transition
@@ -310,7 +310,7 @@ $MOD_LIVEPATCH: pre_patch_callback: $MOD_TARGET -> [MODULE_STATE_COMING] Full fo
 livepatch: pre-patch callback failed for object '$MOD_TARGET'
 livepatch: patch '$MOD_LIVEPATCH' failed for module '$MOD_TARGET', refusing to load module '$MOD_TARGET'
 insmod: ERROR: could not insert module test_modules/$MOD_TARGET.ko: No such device
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 $MOD_LIVEPATCH: pre_unpatch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH': starting unpatching transition
@@ -364,7 +364,7 @@ $MOD_TARGET: ${MOD_TARGET}_exit
 $MOD_LIVEPATCH: pre_unpatch_callback: $MOD_TARGET -> [MODULE_STATE_GOING] Going away
 livepatch: reverting patch '$MOD_LIVEPATCH' on unloading module '$MOD_TARGET'
 $MOD_LIVEPATCH: post_unpatch_callback: $MOD_TARGET -> [MODULE_STATE_GOING] Going away
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 $MOD_LIVEPATCH: pre_unpatch_callback: vmlinux
 $MOD_LIVEPATCH: pre_unpatch_callback: $MOD_TARGET_BUSY -> [MODULE_STATE_LIVE] Normal state
@@ -412,7 +412,7 @@ load_lp_nowait $MOD_LIVEPATCH
 
 # Wait until the livepatch reports in-transition state, i.e. that it's
 # stalled on $MOD_TARGET_BUSY::busymod_work_func()
-loop_until 'grep -q '^1$' /sys/kernel/livepatch/$MOD_LIVEPATCH/transition' ||
+loop_until 'grep -q '^1$' $SYSFS_KLP_DIR/$MOD_LIVEPATCH/transition' ||
 	die "failed to stall transition"
 
 load_mod $MOD_TARGET
@@ -438,7 +438,7 @@ $MOD_TARGET: ${MOD_TARGET}_init
 $MOD_TARGET: ${MOD_TARGET}_exit
 livepatch: reverting patch '$MOD_LIVEPATCH' on unloading module '$MOD_TARGET'
 $MOD_LIVEPATCH: post_unpatch_callback: $MOD_TARGET -> [MODULE_STATE_GOING] Going away
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': reversing transition from patching to unpatching
 livepatch: '$MOD_LIVEPATCH': starting unpatching transition
 livepatch: '$MOD_LIVEPATCH': completing unpatching transition
@@ -483,14 +483,14 @@ livepatch: '$MOD_LIVEPATCH2': starting patching transition
 livepatch: '$MOD_LIVEPATCH2': completing patching transition
 $MOD_LIVEPATCH2: post_patch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH2': patching complete
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH2/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH2/enabled
 livepatch: '$MOD_LIVEPATCH2': initializing unpatching transition
 $MOD_LIVEPATCH2: pre_unpatch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH2': starting unpatching transition
 livepatch: '$MOD_LIVEPATCH2': completing unpatching transition
 $MOD_LIVEPATCH2: post_unpatch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH2': unpatching complete
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 $MOD_LIVEPATCH: pre_unpatch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH': starting unpatching transition
@@ -539,7 +539,7 @@ livepatch: '$MOD_LIVEPATCH2': starting patching transition
 livepatch: '$MOD_LIVEPATCH2': completing patching transition
 $MOD_LIVEPATCH2: post_patch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH2': patching complete
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH2/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH2/enabled
 livepatch: '$MOD_LIVEPATCH2': initializing unpatching transition
 $MOD_LIVEPATCH2: pre_unpatch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH2': starting unpatching transition
diff --git a/tools/testing/selftests/livepatch/test-ftrace.sh b/tools/testing/selftests/livepatch/test-ftrace.sh
index 730218bce99c..fe14f248913a 100755
--- a/tools/testing/selftests/livepatch/test-ftrace.sh
+++ b/tools/testing/selftests/livepatch/test-ftrace.sh
@@ -53,7 +53,7 @@ livepatch: '$MOD_LIVEPATCH': starting patching transition
 livepatch: '$MOD_LIVEPATCH': completing patching transition
 livepatch: '$MOD_LIVEPATCH': patching complete
 livepatch: sysctl: setting key \"kernel.ftrace_enabled\": Device or resource busy
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 livepatch: '$MOD_LIVEPATCH': starting unpatching transition
 livepatch: '$MOD_LIVEPATCH': completing unpatching transition
diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
index bd13257bfdfe..6673023d2b66 100755
--- a/tools/testing/selftests/livepatch/test-livepatch.sh
+++ b/tools/testing/selftests/livepatch/test-livepatch.sh
@@ -39,7 +39,7 @@ livepatch: '$MOD_LIVEPATCH1': initializing patching transition
 livepatch: '$MOD_LIVEPATCH1': starting patching transition
 livepatch: '$MOD_LIVEPATCH1': completing patching transition
 livepatch: '$MOD_LIVEPATCH1': patching complete
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH1/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH1/enabled
 livepatch: '$MOD_LIVEPATCH1': initializing unpatching transition
 livepatch: '$MOD_LIVEPATCH1': starting unpatching transition
 livepatch: '$MOD_LIVEPATCH1': completing unpatching transition
@@ -92,14 +92,14 @@ livepatch: '$MOD_REPLACE': completing patching transition
 livepatch: '$MOD_REPLACE': patching complete
 $MOD_LIVEPATCH1: this has been live patched
 $MOD_REPLACE: this has been live patched
-% echo 0 > /sys/kernel/livepatch/$MOD_REPLACE/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_REPLACE/enabled
 livepatch: '$MOD_REPLACE': initializing unpatching transition
 livepatch: '$MOD_REPLACE': starting unpatching transition
 livepatch: '$MOD_REPLACE': completing unpatching transition
 livepatch: '$MOD_REPLACE': unpatching complete
 % rmmod $MOD_REPLACE
 $MOD_LIVEPATCH1: this has been live patched
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH1/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH1/enabled
 livepatch: '$MOD_LIVEPATCH1': initializing unpatching transition
 livepatch: '$MOD_LIVEPATCH1': starting unpatching transition
 livepatch: '$MOD_LIVEPATCH1': completing unpatching transition
@@ -128,7 +128,7 @@ for mod in $MOD_LIVEPATCH2 $MOD_LIVEPATCH3; do
 	load_lp "$mod"
 done
 
-mods=(/sys/kernel/livepatch/*)
+mods=($SYSFS_KLP_DIR/*)
 nmods=${#mods[@]}
 if [ "$nmods" -ne 3 ]; then
 	die "Expecting three modules listed, found $nmods"
@@ -139,7 +139,7 @@ load_lp $MOD_REPLACE replace=1
 grep 'live patched' /proc/cmdline > /dev/kmsg
 grep 'live patched' /proc/meminfo > /dev/kmsg
 
-loop_until 'mods=(/sys/kernel/livepatch/*); nmods=${#mods[@]}; [[ "$nmods" -eq 1 ]]' ||
+loop_until 'mods=($SYSFS_KLP_DIR/*); nmods=${#mods[@]}; [[ "$nmods" -eq 1 ]]' ||
         die "Expecting only one moduled listed, found $nmods"
 
 # These modules were disabled by the atomic replace
@@ -188,7 +188,7 @@ $MOD_REPLACE: this has been live patched
 % rmmod $MOD_LIVEPATCH2
 % rmmod $MOD_LIVEPATCH1
 $MOD_REPLACE: this has been live patched
-% echo 0 > /sys/kernel/livepatch/$MOD_REPLACE/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_REPLACE/enabled
 livepatch: '$MOD_REPLACE': initializing unpatching transition
 livepatch: '$MOD_REPLACE': starting unpatching transition
 livepatch: '$MOD_REPLACE': completing unpatching transition
diff --git a/tools/testing/selftests/livepatch/test-state.sh b/tools/testing/selftests/livepatch/test-state.sh
index 10a52ac06185..04b66380f8a0 100755
--- a/tools/testing/selftests/livepatch/test-state.sh
+++ b/tools/testing/selftests/livepatch/test-state.sh
@@ -29,7 +29,7 @@ livepatch: '$MOD_LIVEPATCH': completing patching transition
 $MOD_LIVEPATCH: post_patch_callback: vmlinux
 $MOD_LIVEPATCH: fix_console_loglevel: fixing console_loglevel
 livepatch: '$MOD_LIVEPATCH': patching complete
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 $MOD_LIVEPATCH: pre_unpatch_callback: vmlinux
 $MOD_LIVEPATCH: restore_console_loglevel: restoring console_loglevel
@@ -72,7 +72,7 @@ $MOD_LIVEPATCH2: post_patch_callback: vmlinux
 $MOD_LIVEPATCH2: fix_console_loglevel: taking over the console_loglevel change
 livepatch: '$MOD_LIVEPATCH2': patching complete
 % rmmod $MOD_LIVEPATCH
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH2/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH2/enabled
 livepatch: '$MOD_LIVEPATCH2': initializing unpatching transition
 $MOD_LIVEPATCH2: pre_unpatch_callback: vmlinux
 $MOD_LIVEPATCH2: restore_console_loglevel: restoring console_loglevel
@@ -127,7 +127,7 @@ livepatch: '$MOD_LIVEPATCH2': completing patching transition
 $MOD_LIVEPATCH2: post_patch_callback: vmlinux
 $MOD_LIVEPATCH2: fix_console_loglevel: taking over the console_loglevel change
 livepatch: '$MOD_LIVEPATCH2': patching complete
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH2/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH2/enabled
 livepatch: '$MOD_LIVEPATCH2': initializing unpatching transition
 $MOD_LIVEPATCH2: pre_unpatch_callback: vmlinux
 $MOD_LIVEPATCH2: restore_console_loglevel: restoring console_loglevel
@@ -162,7 +162,7 @@ livepatch: '$MOD_LIVEPATCH2': patching complete
 % insmod test_modules/$MOD_LIVEPATCH.ko
 livepatch: Livepatch patch ($MOD_LIVEPATCH) is not compatible with the already installed livepatches.
 insmod: ERROR: could not insert module test_modules/$MOD_LIVEPATCH.ko: Invalid parameters
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH2/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH2/enabled
 livepatch: '$MOD_LIVEPATCH2': initializing unpatching transition
 $MOD_LIVEPATCH2: pre_unpatch_callback: vmlinux
 $MOD_LIVEPATCH2: restore_console_loglevel: restoring console_loglevel
diff --git a/tools/testing/selftests/livepatch/test-syscall.sh b/tools/testing/selftests/livepatch/test-syscall.sh
index 289eb7d4c4b3..9347464a89a0 100755
--- a/tools/testing/selftests/livepatch/test-syscall.sh
+++ b/tools/testing/selftests/livepatch/test-syscall.sh
@@ -46,7 +46,7 @@ livepatch: '$MOD_SYSCALL': starting patching transition
 livepatch: '$MOD_SYSCALL': completing patching transition
 livepatch: '$MOD_SYSCALL': patching complete
 $MOD_SYSCALL: Remaining not livepatched processes: 0
-% echo 0 > /sys/kernel/livepatch/$MOD_SYSCALL/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_SYSCALL/enabled
 livepatch: '$MOD_SYSCALL': initializing unpatching transition
 livepatch: '$MOD_SYSCALL': starting unpatching transition
 livepatch: '$MOD_SYSCALL': completing unpatching transition
diff --git a/tools/testing/selftests/livepatch/test-sysfs.sh b/tools/testing/selftests/livepatch/test-sysfs.sh
index 05a14f5a7bfb..2c91428d2997 100755
--- a/tools/testing/selftests/livepatch/test-sysfs.sh
+++ b/tools/testing/selftests/livepatch/test-sysfs.sh
@@ -34,7 +34,7 @@ livepatch: '$MOD_LIVEPATCH': initializing patching transition
 livepatch: '$MOD_LIVEPATCH': starting patching transition
 livepatch: '$MOD_LIVEPATCH': completing patching transition
 livepatch: '$MOD_LIVEPATCH': patching complete
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 livepatch: '$MOD_LIVEPATCH': starting unpatching transition
 livepatch: '$MOD_LIVEPATCH': completing unpatching transition
@@ -75,7 +75,7 @@ test_klp_callbacks_mod: test_klp_callbacks_mod_exit
 test_klp_callbacks_demo: pre_unpatch_callback: test_klp_callbacks_mod -> [MODULE_STATE_GOING] Going away
 livepatch: reverting patch 'test_klp_callbacks_demo' on unloading module 'test_klp_callbacks_mod'
 test_klp_callbacks_demo: post_unpatch_callback: test_klp_callbacks_mod -> [MODULE_STATE_GOING] Going away
-% echo 0 > /sys/kernel/livepatch/test_klp_callbacks_demo/enabled
+% echo 0 > $SYSFS_KLP_DIR/test_klp_callbacks_demo/enabled
 livepatch: 'test_klp_callbacks_demo': initializing unpatching transition
 test_klp_callbacks_demo: pre_unpatch_callback: vmlinux
 livepatch: 'test_klp_callbacks_demo': starting unpatching transition
@@ -101,7 +101,7 @@ livepatch: '$MOD_LIVEPATCH': initializing patching transition
 livepatch: '$MOD_LIVEPATCH': starting patching transition
 livepatch: '$MOD_LIVEPATCH': completing patching transition
 livepatch: '$MOD_LIVEPATCH': patching complete
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 livepatch: '$MOD_LIVEPATCH': starting unpatching transition
 livepatch: '$MOD_LIVEPATCH': completing unpatching transition
@@ -124,7 +124,7 @@ livepatch: '$MOD_LIVEPATCH': initializing patching transition
 livepatch: '$MOD_LIVEPATCH': starting patching transition
 livepatch: '$MOD_LIVEPATCH': completing patching transition
 livepatch: '$MOD_LIVEPATCH': patching complete
-% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 livepatch: '$MOD_LIVEPATCH': starting unpatching transition
 livepatch: '$MOD_LIVEPATCH': completing unpatching transition
-- 
2.47.0

[PATCH v5 2/3] selftests: livepatch: save and restore kprobe state

[Michael Vetter]

Save the state of /sys/kernel/debug/kprobes/enabled
during setup_config() and restore it during cleanup().

This is in preparation for a future commit that will add a test
that should confirm that we cannot livepatch a kprobed function
if that kprobe has a post handler.

Signed-off-by: Michael Vetter <mvetter@suse.com>
---
 tools/testing/selftests/livepatch/functions.sh | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
index e0e7f8db894c..e78e0e16ad4d 100644
--- a/tools/testing/selftests/livepatch/functions.sh
+++ b/tools/testing/selftests/livepatch/functions.sh
@@ -6,7 +6,10 @@
 
 MAX_RETRIES=600
 RETRY_INTERVAL=".1"	# seconds
-SYSFS_KLP_DIR="/sys/kernel/livepatch"
+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"
 
 # Kselftest framework requirement - SKIP code is 4
 ksft_skip=4
@@ -55,22 +58,26 @@ function die() {
 }
 
 function push_config() {
-	DYNAMIC_DEBUG=$(grep '^kernel/livepatch' /sys/kernel/debug/dynamic_debug/control | \
+	DYNAMIC_DEBUG=$(grep '^kernel/livepatch' "$SYSFS_DEBUG_DIR/dynamic_debug/control" | \
 			awk -F'[: ]' '{print "file " $1 " line " $2 " " $4}')
 	FTRACE_ENABLED=$(sysctl --values kernel.ftrace_enabled)
+	KPROBE_ENABLED=$(cat "$SYSFS_KPROBES_DIR/enabled")
 }
 
 function pop_config() {
 	if [[ -n "$DYNAMIC_DEBUG" ]]; then
-		echo -n "$DYNAMIC_DEBUG" > /sys/kernel/debug/dynamic_debug/control
+		echo -n "$DYNAMIC_DEBUG" > "$SYSFS_DEBUG_DIR/dynamic_debug/control"
 	fi
 	if [[ -n "$FTRACE_ENABLED" ]]; then
 		sysctl kernel.ftrace_enabled="$FTRACE_ENABLED" &> /dev/null
 	fi
+	if [[ -n "$KPROBE_ENABLED" ]]; then
+		echo "$KPROBE_ENABLED" > "$SYSFS_KPROBES_DIR/enabled"
+	fi
 }
 
 function set_dynamic_debug() {
-        cat <<-EOF > /sys/kernel/debug/dynamic_debug/control
+        cat <<-EOF > "$SYSFS_DEBUG_DIR/dynamic_debug/control"
 		file kernel/livepatch/* +p
 		func klp_try_switch_task -p
 		EOF
-- 
2.47.0

[PATCH v5 3/3] selftests: livepatch: test livepatching a kprobed function

[Michael Vetter]

The test proves that a function that is being kprobed and uses a
post_handler cannot be livepatched.

Only one ftrace_ops with FTRACE_OPS_FL_IPMODIFY set may be registered
to any given function at a time.

Note that the conflicting kprobe could not be created using the
tracefs interface, see Documentation/trace/kprobetrace.rst.
This interface uses only the pre_handler(), see alloc_trace_kprobe().
But FTRACE_OPS_FL_IPMODIFY is used only when the kprobe is using a
post_handler, see arm_kprobe_ftrace().

Signed-off-by: Michael Vetter <mvetter@suse.com>
---
 tools/testing/selftests/livepatch/Makefile    |  3 +-
 .../selftests/livepatch/test-kprobe.sh        | 62 +++++++++++++++++++
 .../selftests/livepatch/test_modules/Makefile |  3 +-
 .../livepatch/test_modules/test_klp_kprobe.c  | 38 ++++++++++++
 4 files changed, 104 insertions(+), 2 deletions(-)
 create mode 100755 tools/testing/selftests/livepatch/test-kprobe.sh
 create mode 100644 tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c

diff --git a/tools/testing/selftests/livepatch/Makefile b/tools/testing/selftests/livepatch/Makefile
index 35418a4790be..a080eb54a215 100644
--- a/tools/testing/selftests/livepatch/Makefile
+++ b/tools/testing/selftests/livepatch/Makefile
@@ -10,7 +10,8 @@ TEST_PROGS := \
 	test-state.sh \
 	test-ftrace.sh \
 	test-sysfs.sh \
-	test-syscall.sh
+	test-syscall.sh \
+	test-kprobe.sh
 
 TEST_FILES := settings
 
diff --git a/tools/testing/selftests/livepatch/test-kprobe.sh b/tools/testing/selftests/livepatch/test-kprobe.sh
new file mode 100755
index 000000000000..115065156016
--- /dev/null
+++ b/tools/testing/selftests/livepatch/test-kprobe.sh
@@ -0,0 +1,62 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2024 SUSE
+# Author: Michael Vetter <mvetter@suse.com>
+
+. $(dirname $0)/functions.sh
+
+MOD_LIVEPATCH=test_klp_livepatch
+MOD_KPROBE=test_klp_kprobe
+
+setup_config
+
+# Kprobe a function and verify that we can't livepatch that same function
+# when it uses a post_handler since only one IPMODIFY maybe be registered
+# to any given function at a time.
+
+start_test "livepatch interaction with kprobed function with post_handler"
+
+echo 1 > "$SYSFS_KPROBES_DIR/enabled"
+
+load_mod $MOD_KPROBE has_post_handler=true
+load_failing_mod $MOD_LIVEPATCH
+unload_mod $MOD_KPROBE
+
+check_result "% insmod test_modules/test_klp_kprobe.ko has_post_handler=true
+% insmod test_modules/$MOD_LIVEPATCH.ko
+livepatch: enabling patch '$MOD_LIVEPATCH'
+livepatch: '$MOD_LIVEPATCH': initializing patching transition
+livepatch: failed to register ftrace handler for function 'cmdline_proc_show' (-16)
+livepatch: failed to patch object 'vmlinux'
+livepatch: failed to enable patch '$MOD_LIVEPATCH'
+livepatch: '$MOD_LIVEPATCH': canceling patching transition, going to unpatch
+livepatch: '$MOD_LIVEPATCH': completing unpatching transition
+livepatch: '$MOD_LIVEPATCH': unpatching complete
+insmod: ERROR: could not insert module test_modules/$MOD_LIVEPATCH.ko: Device or resource busy
+% rmmod test_klp_kprobe"
+
+start_test "livepatch interaction with kprobed function without post_handler"
+
+load_mod $MOD_KPROBE has_post_handler=false
+load_lp $MOD_LIVEPATCH
+
+unload_mod $MOD_KPROBE
+disable_lp $MOD_LIVEPATCH
+unload_lp $MOD_LIVEPATCH
+
+check_result "% insmod test_modules/test_klp_kprobe.ko has_post_handler=false
+% insmod test_modules/$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: '$MOD_LIVEPATCH': patching complete
+% rmmod test_klp_kprobe
+% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
+livepatch: '$MOD_LIVEPATCH': starting unpatching transition
+livepatch: '$MOD_LIVEPATCH': completing unpatching transition
+livepatch: '$MOD_LIVEPATCH': unpatching complete
+% rmmod $MOD_LIVEPATCH"
+
+exit 0
diff --git a/tools/testing/selftests/livepatch/test_modules/Makefile b/tools/testing/selftests/livepatch/test_modules/Makefile
index e6e638c4bcba..939230e571f5 100644
--- a/tools/testing/selftests/livepatch/test_modules/Makefile
+++ b/tools/testing/selftests/livepatch/test_modules/Makefile
@@ -6,11 +6,12 @@ obj-m += test_klp_atomic_replace.o \
 	test_klp_callbacks_demo.o \
 	test_klp_callbacks_demo2.o \
 	test_klp_callbacks_mod.o \
+	test_klp_kprobe.o \
 	test_klp_livepatch.o \
+	test_klp_shadow_vars.o \
 	test_klp_state.o \
 	test_klp_state2.o \
 	test_klp_state3.o \
-	test_klp_shadow_vars.o \
 	test_klp_syscall.o
 
 # Ensure that KDIR exists, otherwise skip the compilation
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c b/tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c
new file mode 100644
index 000000000000..67a8d29012f6
--- /dev/null
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2024 Marcos Paulo de Souza <mpdesouza@suse.com>
+// Copyright (C) 2024 Michael Vetter <mvetter@suse.com>
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/kprobes.h>
+
+static bool has_post_handler = true;
+module_param(has_post_handler, bool, 0444);
+
+static void __kprobes post_handler(struct kprobe *p, struct pt_regs *regs,
+				unsigned long flags)
+{
+}
+
+static struct kprobe kp = {
+	.symbol_name = "cmdline_proc_show",
+};
+
+static int __init kprobe_init(void)
+{
+	if (has_post_handler)
+		kp.post_handler = post_handler;
+
+	return register_kprobe(&kp);
+}
+
+static void __exit kprobe_exit(void)
+{
+	unregister_kprobe(&kp);
+}
+
+module_init(kprobe_init)
+module_exit(kprobe_exit)
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Michael Vetter <mvetter@suse.com>");
+MODULE_DESCRIPTION("Livepatch test: kprobe function");
-- 
2.47.0

Re: [PATCH v5 1/3] selftests: livepatch: rename KLP_SYSFS_DIR to SYSFS_KLP_DIR

[Joe Lawrence]

On 10/17/24 16:01, Michael Vetter wrote:
> @@ -246,12 +246,12 @@ function unload_lp() {
>  function disable_lp() {
>  	local mod="$1"
>  
> -	log "% echo 0 > /sys/kernel/livepatch/$mod/enabled"
> -	echo 0 > /sys/kernel/livepatch/"$mod"/enabled
> +	log "% echo 0 > $SYSFS_KLP_DIR/$mod/enabled"
> +	echo 0 > "$SYSFS_KLP_DIR"/mod"/enabled

Nit: syntax error here, should be (quotation fix and $mod is a variable):

  echo 0 > "$SYSFS_KLP_DIR/$mod/enabled"

With that, the test works for me.

-- 
Joe

Re: [PATCH v5 0/3] selftests: livepatch: test livepatching a kprobed function

[Joe Lawrence]

On 10/17/24 16:01, Michael Vetter wrote:
> Thanks for all the reviews.
> 
> V5:
> Replace /sys/kernel/livepatch also in other/already existing tests.
> Improve commit message of 3rd patch.
> 
> V4:
> Use variable for /sys/kernel/debug.
> Be consistent with "" around variables.
> Fix path in commit message to /sys/kernel/debug/kprobes/enabled.
> 
> V3:
> Save and restore kprobe state also when test fails, by integrating it
> into setup_config() and cleanup().
> Rename SYSFS variables in a more logical way.
> Sort test modules in alphabetical order.
> Rename module description.
> 
> V2:
> Save and restore kprobe state.
> 
> Michael Vetter (3):
>   selftests: livepatch: rename KLP_SYSFS_DIR to SYSFS_KLP_DIR
>   selftests: livepatch: save and restore kprobe state
>   selftests: livepatch: test livepatching a kprobed function
> 
>  tools/testing/selftests/livepatch/Makefile    |  3 +-
>  .../testing/selftests/livepatch/functions.sh  | 29 +++++----
>  .../selftests/livepatch/test-callbacks.sh     | 24 +++----
>  .../selftests/livepatch/test-ftrace.sh        |  2 +-
>  .../selftests/livepatch/test-kprobe.sh        | 62 +++++++++++++++++++
>  .../selftests/livepatch/test-livepatch.sh     | 12 ++--
>  .../testing/selftests/livepatch/test-state.sh |  8 +--
>  .../selftests/livepatch/test-syscall.sh       |  2 +-
>  .../testing/selftests/livepatch/test-sysfs.sh |  8 +--
>  .../selftests/livepatch/test_modules/Makefile |  3 +-
>  .../livepatch/test_modules/test_klp_kprobe.c  | 38 ++++++++++++
>  11 files changed, 150 insertions(+), 41 deletions(-)
>  create mode 100755 tools/testing/selftests/livepatch/test-kprobe.sh
>  create mode 100644 tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c
> 

With the small syntax error fixed in unload_lp(),

Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com>

Thanks, Michael, this is a good test to add to the suite.

-- 
Joe

Re: [PATCH v5 0/3] selftests: livepatch: test livepatching a kprobed function

[Marcos Paulo de Souza]

On Thu, 2024-10-17 at 22:01 +0200, Michael Vetter wrote:
> Thanks for all the reviews.
> 
> V5:
> Replace /sys/kernel/livepatch also in other/already existing tests.
> Improve commit message of 3rd patch.
> 
> V4:
> Use variable for /sys/kernel/debug.
> Be consistent with "" around variables.
> Fix path in commit message to /sys/kernel/debug/kprobes/enabled.
> 
> V3:
> Save and restore kprobe state also when test fails, by integrating it
> into setup_config() and cleanup().
> Rename SYSFS variables in a more logical way.
> Sort test modules in alphabetical order.
> Rename module description.
> 
> V2:
> Save and restore kprobe state.

With the syntax error pointed out by Joe resolved, you can add:

Tested-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: Marcos Paulo de Souza <mpdesouza@suse.com>

> 
> Michael Vetter (3):
>   selftests: livepatch: rename KLP_SYSFS_DIR to SYSFS_KLP_DIR
>   selftests: livepatch: save and restore kprobe state
>   selftests: livepatch: test livepatching a kprobed function
> 
>  tools/testing/selftests/livepatch/Makefile    |  3 +-
>  .../testing/selftests/livepatch/functions.sh  | 29 +++++----
>  .../selftests/livepatch/test-callbacks.sh     | 24 +++----
>  .../selftests/livepatch/test-ftrace.sh        |  2 +-
>  .../selftests/livepatch/test-kprobe.sh        | 62
> +++++++++++++++++++
>  .../selftests/livepatch/test-livepatch.sh     | 12 ++--
>  .../testing/selftests/livepatch/test-state.sh |  8 +--
>  .../selftests/livepatch/test-syscall.sh       |  2 +-
>  .../testing/selftests/livepatch/test-sysfs.sh |  8 +--
>  .../selftests/livepatch/test_modules/Makefile |  3 +-
>  .../livepatch/test_modules/test_klp_kprobe.c  | 38 ++++++++++++
>  11 files changed, 150 insertions(+), 41 deletions(-)
>  create mode 100755 tools/testing/selftests/livepatch/test-kprobe.sh
>  create mode 100644
> tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c
> 

Re: [PATCH v5 0/3] selftests: livepatch: test livepatching a kprobed function

[Petr Mladek]

On Thu 2024-10-17 22:01:29, Michael Vetter wrote:
> Thanks for all the reviews.
> 
> V5:
> Replace /sys/kernel/livepatch also in other/already existing tests.
> Improve commit message of 3rd patch.

With the syntax error fixed by Joe:

Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>

Note: I could fix the syntax error when pushing the patchset.
      There is no need to send v6 if this is the only problem.

Best Regards,
Petr

Re: [PATCH v5 1/3] selftests: livepatch: rename KLP_SYSFS_DIR to SYSFS_KLP_DIR

[Miroslav Benes]

On Thu, 17 Oct 2024, Michael Vetter wrote:

> This naming makes more sense according to the directory structure.
> Especially when we later add more paths.
> 
> Addtionally replace `/sys/kernel/livepatch` with `$SYSFS_KLP_DIR` in
> the livepatch test files.
> 
> Signed-off-by: Michael Vetter <mvetter@suse.com>

Reviewed-by: Miroslav Benes <mbenes@suse.cz>

M

Re: [PATCH v5 2/3] selftests: livepatch: save and restore kprobe state

[Miroslav Benes]

Hi,

On Thu, 17 Oct 2024, Michael Vetter wrote:

> Save the state of /sys/kernel/debug/kprobes/enabled
> during setup_config() and restore it during cleanup().
> 
> This is in preparation for a future commit that will add a test
> that should confirm that we cannot livepatch a kprobed function
> if that kprobe has a post handler.
> 
> Signed-off-by: Michael Vetter <mvetter@suse.com>
> ---
>  tools/testing/selftests/livepatch/functions.sh | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
> index e0e7f8db894c..e78e0e16ad4d 100644
> --- a/tools/testing/selftests/livepatch/functions.sh
> +++ b/tools/testing/selftests/livepatch/functions.sh
> @@ -6,7 +6,10 @@
>  
>  MAX_RETRIES=600
>  RETRY_INTERVAL=".1"	# seconds
> -SYSFS_KLP_DIR="/sys/kernel/livepatch"
> +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"

there are still two occurrences of /sys/kernel/ in test-syscall.sh which 
can be replaced with $SYSFS_KERNEL_DIR now. I suppose that Petr can fix 
that when applying as well.

The patch also contains two separate things... the cleanup and the kprobe 
state handling. Ideally, it should be split but unless someone else also 
speaks up, I can certainly live with the current state.

With that

Reviewed-by: Miroslav Benes <mbenes@suse.cz>

M

Re: [PATCH v5 3/3] selftests: livepatch: test livepatching a kprobed function

[Miroslav Benes]

On Thu, 17 Oct 2024, Michael Vetter wrote:

> The test proves that a function that is being kprobed and uses a
> post_handler cannot be livepatched.
> 
> Only one ftrace_ops with FTRACE_OPS_FL_IPMODIFY set may be registered
> to any given function at a time.
> 
> Note that the conflicting kprobe could not be created using the
> tracefs interface, see Documentation/trace/kprobetrace.rst.
> This interface uses only the pre_handler(), see alloc_trace_kprobe().
> But FTRACE_OPS_FL_IPMODIFY is used only when the kprobe is using a
> post_handler, see arm_kprobe_ftrace().
> 
> Signed-off-by: Michael Vetter <mvetter@suse.com>

Nice test.

Reviewed-by: Miroslav Benes <mbenes@suse.cz>

Thank you,
Miroslav

Re: [PATCH v5 0/3] selftests: livepatch: test livepatching a kprobed function

[Petr Mladek]

On Thu 2024-10-17 22:01:29, Michael Vetter wrote:
> Thanks for all the reviews.
> 
> V5:
> Replace /sys/kernel/livepatch also in other/already existing tests.
> Improve commit message of 3rd patch.

JFYI, I have committed the patchset into livepatching.git,
branch for-6.13/selftests-kprobe.

I have fixed the wrong substitution in the 1st patch as suggested by Joe.

Also I have made two substitutions in test-syscall.sh in the 2nd patch
as suggested by Miroslav.

I would personally prefer to do the substitutions of existing paths
in a separate patch (same as Miroslav). But I do not think that
it was worth another respin. It would just increase risk of more
typos. And we have already spent enough time on this ;-)

Best Regards,
Petr