path: root/tools/testing/selftests/livepatch
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authorDavid Vernet <void@manifault.com>2022-02-16 08:11:01 -0800
committerPetr Mladek <pmladek@suse.com>2022-02-23 16:42:00 +0100
commit4327b9eaf8a4ddd2c534e4f4ed7c949cf3d2be1e (patch)
treea888d899b26600900c2e5bab9783793e87b63713 /tools/testing/selftests/livepatch
parentMerge tag 'livepatching-for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching (diff)
livepatch: Skip livepatch tests if ftrace cannot be configured
livepatch has a set of selftests that are used to validate the behavior of the livepatching subsystem. One of the testcases in the livepatch testsuite is test-ftrace.sh, which among other things, validates that livepatching gracefully fails when ftrace is disabled. In the event that ftrace cannot be disabled using 'sysctl kernel.ftrace_enabled=0', the test will fail later due to it unexpectedly successfully loading the test_klp_livepatch module. While the livepatch selftests are careful to remove any of the livepatch test modules between testcases to avoid this situation, ftrace may still fail to be disabled if another trace is active on the system that was enabled with FTRACE_OPS_FL_PERMANENT. For example, any active BPF programs that use trampolines will cause this test to fail due to the trampoline being implemented with register_ftrace_direct(). The following is an example of such a trace: tcp_drop (1) R I D tramp: ftrace_regs_caller+0x0/0x58 (call_direct_funcs+0x0/0x30) direct-->bpf_trampoline_6442550536_0+0x0/0x1000 In order to make the test more resilient to system state that is out of its control, this patch updates set_ftrace_enabled() to detect sysctl failures, and skip the testrun when appropriate. Suggested-by: Petr Mladek <pmladek@suse.com> Signed-off-by: David Vernet <void@manifault.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Petr Mladek <pmladek@suse.com> Tested-by: Petr Mladek <pmladek@suse.com> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20220216161100.3243100-1-void@manifault.com
Diffstat (limited to 'tools/testing/selftests/livepatch')
2 files changed, 21 insertions, 4 deletions
diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
index 846c7ed71556..9230b869371d 100644
--- a/tools/testing/selftests/livepatch/functions.sh
+++ b/tools/testing/selftests/livepatch/functions.sh
@@ -75,9 +75,25 @@ function set_dynamic_debug() {
function set_ftrace_enabled() {
- result=$(sysctl -q kernel.ftrace_enabled="$1" 2>&1 && \
- sysctl kernel.ftrace_enabled 2>&1)
- echo "livepatch: $result" > /dev/kmsg
+ local can_fail=0
+ if [[ "$1" == "--fail" ]] ; then
+ can_fail=1
+ shift
+ fi
+ local err=$(sysctl -q kernel.ftrace_enabled="$1" 2>&1)
+ local result=$(sysctl --values kernel.ftrace_enabled)
+ if [[ "$result" != "$1" ]] ; then
+ if [[ $can_fail -eq 1 ]] ; then
+ echo "livepatch: $err" > /dev/kmsg
+ return
+ fi
+ skip "failed to set kernel.ftrace_enabled = $1"
+ fi
+ echo "livepatch: kernel.ftrace_enabled = $result" > /dev/kmsg
function cleanup() {
diff --git a/tools/testing/selftests/livepatch/test-ftrace.sh b/tools/testing/selftests/livepatch/test-ftrace.sh
index 552e165512f4..825540a5194d 100755
--- a/tools/testing/selftests/livepatch/test-ftrace.sh
+++ b/tools/testing/selftests/livepatch/test-ftrace.sh
@@ -25,7 +25,8 @@ if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" ]]
die "livepatch kselftest(s) failed"
-set_ftrace_enabled 0
+# Check that ftrace could not get disabled when a livepatch is enabled
+set_ftrace_enabled --fail 0
if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" ]] ; then
echo -e "FAIL\n\n"
die "livepatch kselftest(s) failed"