[PATCH blktests] blktrace/001: Skip test when kernel lockdown is enabled

[Disha Goel <disgoel@linux.ibm.com>]

The blktrace/001 test fails on systems with Secure Boot enabled due to
kernel lockdown preventing access to debugfs. The test attempts to run
blktrace which requires access to /sys/kernel/debug/block/*/trace*
files, but kernel lockdown (enabled automatically with Secure Boot)
blocks this access, resulting in "Operation not permitted" errors.

Add _have_debugfs_access() helper function to detect kernel lockdown by
checking /sys/kernel/security/lockdown for [integrity] or
[confidentiality] modes. When detected, the test now skips gracefully
with a clear message: "kernel lockdown is enabled (Secure Boot may be
active)".

Also add _have_configfs check which was missing. The test uses
_configure_null_blk() which requires configfs to be mounted at
/sys/kernel/config.

Signed-off-by: Disha Goel <disgoel@linux.ibm.com>
---
 common/rc          | 14 ++++++++++++++
 tests/blktrace/001 |  2 ++
 2 files changed, 16 insertions(+)

diff --git a/common/rc b/common/rc
index 5350057..50d63e7 100644
--- a/common/rc
+++ b/common/rc
@@ -205,6 +205,20 @@ _have_blktrace() {
 	_have_program blktrace
 }
 
+_have_debugfs_access() {
+        # Check if kernel lockdown is preventing debugfs access
+        # This happens when Secure Boot is enabled
+        if [[ -f /sys/kernel/security/lockdown ]]; then
+                local lockdown_state
+                lockdown_state=$(cat /sys/kernel/security/lockdown 2>/dev/null)
+                if [[ "$lockdown_state" =~ \[integrity\]|\[confidentiality\] ]]; then
+                        SKIP_REASONS+=("kernel lockdown is enabled (Secure Boot may be active)")
+                        return 1
+                fi
+        fi
+        return 0
+}
+
 _have_configfs() {
 	if ! findmnt -t configfs /sys/kernel/config >/dev/null; then
 		SKIP_REASONS+=("configfs is not mounted at /sys/kernel/config")
diff --git a/tests/blktrace/001 b/tests/blktrace/001
index 2cdad02..4fe7807 100755
--- a/tests/blktrace/001
+++ b/tests/blktrace/001
@@ -22,6 +22,8 @@ requires() {
 	_have_program blkzone
 	_have_null_blk
 	_have_module_param null_blk zoned
+	_have_configfs
+        _have_debugfs_access
 }
 
 test() {
-- 
2.45.1