9 files changed, 979 insertions, 0 deletions

diff --git a/tools/testing/selftests/liveupdate/.gitignore b/tools/testing/selftests/liveupdate/.gitignore
new file mode 100644
index 000000000000..661827083ab6
--- /dev/null
+++ b/tools/testing/selftests/liveupdate/.gitignore
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0-only
+*
+!/**/
+!*.c
+!*.h
+!*.sh
+!.gitignore
+!config
+!Makefile
diff --git a/tools/testing/selftests/liveupdate/Makefile b/tools/testing/selftests/liveupdate/Makefile
new file mode 100644
index 000000000000..080754787ede
--- /dev/null
+++ b/tools/testing/selftests/liveupdate/Makefile
@@ -0,0 +1,34 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+LIB_C += luo_test_utils.c
+
+TEST_GEN_PROGS += liveupdate
+
+TEST_GEN_PROGS_EXTENDED += luo_kexec_simple
+TEST_GEN_PROGS_EXTENDED += luo_multi_session
+
+TEST_FILES += do_kexec.sh
+
+include ../lib.mk
+
+CFLAGS += $(KHDR_INCLUDES)
+CFLAGS += -Wall -O2 -Wno-unused-function
+CFLAGS += -MD
+
+LIB_O := $(patsubst %.c, $(OUTPUT)/%.o, $(LIB_C))
+TEST_O := $(patsubst %, %.o, $(TEST_GEN_PROGS))
+TEST_O += $(patsubst %, %.o, $(TEST_GEN_PROGS_EXTENDED))
+
+TEST_DEP_FILES := $(patsubst %.o, %.d, $(LIB_O))
+TEST_DEP_FILES += $(patsubst %.o, %.d, $(TEST_O))
+-include $(TEST_DEP_FILES)
+
+$(LIB_O): $(OUTPUT)/%.o: %.c
+	$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o $@
+
+$(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED): $(OUTPUT)/%: %.o $(LIB_O)
+	$(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $(TARGET_ARCH) $< $(LIB_O) $(LDLIBS) -o $@
+
+EXTRA_CLEAN += $(LIB_O)
+EXTRA_CLEAN += $(TEST_O)
+EXTRA_CLEAN += $(TEST_DEP_FILES)
diff --git a/tools/testing/selftests/liveupdate/config b/tools/testing/selftests/liveupdate/config
new file mode 100644
index 000000000000..91d03f9a6a39
--- /dev/null
+++ b/tools/testing/selftests/liveupdate/config
@@ -0,0 +1,11 @@
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_KEXEC_FILE=y
+CONFIG_KEXEC_HANDOVER=y
+CONFIG_KEXEC_HANDOVER_ENABLE_DEFAULT=y
+CONFIG_KEXEC_HANDOVER_DEBUGFS=y
+CONFIG_KEXEC_HANDOVER_DEBUG=y
+CONFIG_LIVEUPDATE=y
+CONFIG_LIVEUPDATE_TEST=y
+CONFIG_MEMFD_CREATE=y
+CONFIG_TMPFS=y
+CONFIG_SHMEM=y
diff --git a/tools/testing/selftests/liveupdate/do_kexec.sh b/tools/testing/selftests/liveupdate/do_kexec.sh
new file mode 100755
index 000000000000..3c7c6cafbef8
--- /dev/null
+++ b/tools/testing/selftests/liveupdate/do_kexec.sh
@@ -0,0 +1,16 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+set -e
+
+# Use $KERNEL and $INITRAMFS to pass custom Kernel and optional initramfs
+
+KERNEL="${KERNEL:-/boot/bzImage}"
+set -- -l -s --reuse-cmdline "$KERNEL"
+
+INITRAMFS="${INITRAMFS:-/boot/initramfs}"
+if [ -f "$INITRAMFS" ]; then
+    set -- "$@" --initrd="$INITRAMFS"
+fi
+
+kexec "$@"
+kexec -e
diff --git a/tools/testing/selftests/liveupdate/liveupdate.c b/tools/testing/selftests/liveupdate/liveupdate.c
new file mode 100644
index 000000000000..c2878e3d5ef9
--- /dev/null
+++ b/tools/testing/selftests/liveupdate/liveupdate.c
@@ -0,0 +1,348 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (c) 2025, Google LLC.
+ * Pasha Tatashin <pasha.tatashin@soleen.com>
+ */
+
+/*
+ * Selftests for the Live Update Orchestrator.
+ * This test suite verifies the functionality and behavior of the
+ * /dev/liveupdate character device and its session management capabilities.
+ *
+ * Tests include:
+ * - Device access: basic open/close, and enforcement of exclusive access.
+ * - Session management: creation of unique sessions, and duplicate name detection.
+ * - Resource preservation: successfully preserving individual and multiple memfds,
+ *   verifying contents remain accessible.
+ * - Complex multi-session scenarios involving mixed empty and populated files.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+#include <linux/liveupdate.h>
+
+#include "../kselftest.h"
+#include "../kselftest_harness.h"
+
+#define LIVEUPDATE_DEV "/dev/liveupdate"
+
+FIXTURE(liveupdate_device) {
+	int fd1;
+	int fd2;
+};
+
+FIXTURE_SETUP(liveupdate_device)
+{
+	self->fd1 = -1;
+	self->fd2 = -1;
+}
+
+FIXTURE_TEARDOWN(liveupdate_device)
+{
+	if (self->fd1 >= 0)
+		close(self->fd1);
+	if (self->fd2 >= 0)
+		close(self->fd2);
+}
+
+/*
+ * Test Case: Basic Open and Close
+ *
+ * Verifies that the /dev/liveupdate device can be opened and subsequently
+ * closed without errors. Skips if the device does not exist.
+ */
+TEST_F(liveupdate_device, basic_open_close)
+{
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist.", LIVEUPDATE_DEV);
+
+	ASSERT_GE(self->fd1, 0);
+	ASSERT_EQ(close(self->fd1), 0);
+	self->fd1 = -1;
+}
+
+/*
+ * Test Case: Exclusive Open Enforcement
+ *
+ * Verifies that the /dev/liveupdate device can only be opened by one process
+ * at a time. It checks that a second attempt to open the device fails with
+ * the EBUSY error code.
+ */
+TEST_F(liveupdate_device, exclusive_open)
+{
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist.", LIVEUPDATE_DEV);
+
+	ASSERT_GE(self->fd1, 0);
+	self->fd2 = open(LIVEUPDATE_DEV, O_RDWR);
+	EXPECT_LT(self->fd2, 0);
+	EXPECT_EQ(errno, EBUSY);
+}
+
+/* Helper function to create a LUO session via ioctl. */
+static int create_session(int lu_fd, const char *name)
+{
+	struct liveupdate_ioctl_create_session args = {};
+
+	args.size = sizeof(args);
+	strncpy((char *)args.name, name, sizeof(args.name) - 1);
+
+	if (ioctl(lu_fd, LIVEUPDATE_IOCTL_CREATE_SESSION, &args))
+		return -errno;
+
+	return args.fd;
+}
+
+/*
+ * Test Case: Create Duplicate Session
+ *
+ * Verifies that attempting to create two sessions with the same name fails
+ * on the second attempt with EEXIST.
+ */
+TEST_F(liveupdate_device, create_duplicate_session)
+{
+	int session_fd1, session_fd2;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd1 = create_session(self->fd1, "duplicate-session-test");
+	ASSERT_GE(session_fd1, 0);
+
+	session_fd2 = create_session(self->fd1, "duplicate-session-test");
+	EXPECT_LT(session_fd2, 0);
+	EXPECT_EQ(-session_fd2, EEXIST);
+
+	ASSERT_EQ(close(session_fd1), 0);
+}
+
+/*
+ * Test Case: Create Distinct Sessions
+ *
+ * Verifies that creating two sessions with different names succeeds.
+ */
+TEST_F(liveupdate_device, create_distinct_sessions)
+{
+	int session_fd1, session_fd2;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd1 = create_session(self->fd1, "distinct-session-1");
+	ASSERT_GE(session_fd1, 0);
+
+	session_fd2 = create_session(self->fd1, "distinct-session-2");
+	ASSERT_GE(session_fd2, 0);
+
+	ASSERT_EQ(close(session_fd1), 0);
+	ASSERT_EQ(close(session_fd2), 0);
+}
+
+static int preserve_fd(int session_fd, int fd_to_preserve, __u64 token)
+{
+	struct liveupdate_session_preserve_fd args = {};
+
+	args.size = sizeof(args);
+	args.fd = fd_to_preserve;
+	args.token = token;
+
+	if (ioctl(session_fd, LIVEUPDATE_SESSION_PRESERVE_FD, &args))
+		return -errno;
+
+	return 0;
+}
+
+/*
+ * Test Case: Preserve MemFD
+ *
+ * Verifies that a valid memfd can be successfully preserved in a session and
+ * that its contents remain intact after the preservation call.
+ */
+TEST_F(liveupdate_device, preserve_memfd)
+{
+	const char *test_str = "hello liveupdate";
+	char read_buf[64] = {};
+	int session_fd, mem_fd;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd = create_session(self->fd1, "preserve-memfd-test");
+	ASSERT_GE(session_fd, 0);
+
+	mem_fd = memfd_create("test-memfd", 0);
+	ASSERT_GE(mem_fd, 0);
+
+	ASSERT_EQ(write(mem_fd, test_str, strlen(test_str)), strlen(test_str));
+	ASSERT_EQ(preserve_fd(session_fd, mem_fd, 0x1234), 0);
+	ASSERT_EQ(close(session_fd), 0);
+
+	ASSERT_EQ(lseek(mem_fd, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd, read_buf, sizeof(read_buf)), strlen(test_str));
+	ASSERT_STREQ(read_buf, test_str);
+	ASSERT_EQ(close(mem_fd), 0);
+}
+
+/*
+ * Test Case: Preserve Multiple MemFDs
+ *
+ * Verifies that multiple memfds can be preserved in a single session,
+ * each with a unique token, and that their contents remain distinct and
+ * correct after preservation.
+ */
+TEST_F(liveupdate_device, preserve_multiple_memfds)
+{
+	const char *test_str1 = "data for memfd one";
+	const char *test_str2 = "data for memfd two";
+	char read_buf[64] = {};
+	int session_fd, mem_fd1, mem_fd2;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd = create_session(self->fd1, "preserve-multi-memfd-test");
+	ASSERT_GE(session_fd, 0);
+
+	mem_fd1 = memfd_create("test-memfd-1", 0);
+	ASSERT_GE(mem_fd1, 0);
+	mem_fd2 = memfd_create("test-memfd-2", 0);
+	ASSERT_GE(mem_fd2, 0);
+
+	ASSERT_EQ(write(mem_fd1, test_str1, strlen(test_str1)), strlen(test_str1));
+	ASSERT_EQ(write(mem_fd2, test_str2, strlen(test_str2)), strlen(test_str2));
+
+	ASSERT_EQ(preserve_fd(session_fd, mem_fd1, 0xAAAA), 0);
+	ASSERT_EQ(preserve_fd(session_fd, mem_fd2, 0xBBBB), 0);
+
+	memset(read_buf, 0, sizeof(read_buf));
+	ASSERT_EQ(lseek(mem_fd1, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd1, read_buf, sizeof(read_buf)), strlen(test_str1));
+	ASSERT_STREQ(read_buf, test_str1);
+
+	memset(read_buf, 0, sizeof(read_buf));
+	ASSERT_EQ(lseek(mem_fd2, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd2, read_buf, sizeof(read_buf)), strlen(test_str2));
+	ASSERT_STREQ(read_buf, test_str2);
+
+	ASSERT_EQ(close(mem_fd1), 0);
+	ASSERT_EQ(close(mem_fd2), 0);
+	ASSERT_EQ(close(session_fd), 0);
+}
+
+/*
+ * Test Case: Preserve Complex Scenario
+ *
+ * Verifies a more complex scenario with multiple sessions and a mix of empty
+ * and non-empty memfds distributed across them.
+ */
+TEST_F(liveupdate_device, preserve_complex_scenario)
+{
+	const char *data1 = "data for session 1";
+	const char *data2 = "data for session 2";
+	char read_buf[64] = {};
+	int session_fd1, session_fd2;
+	int mem_fd_data1, mem_fd_empty1, mem_fd_data2, mem_fd_empty2;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd1 = create_session(self->fd1, "complex-session-1");
+	ASSERT_GE(session_fd1, 0);
+	session_fd2 = create_session(self->fd1, "complex-session-2");
+	ASSERT_GE(session_fd2, 0);
+
+	mem_fd_data1 = memfd_create("data1", 0);
+	ASSERT_GE(mem_fd_data1, 0);
+	ASSERT_EQ(write(mem_fd_data1, data1, strlen(data1)), strlen(data1));
+
+	mem_fd_empty1 = memfd_create("empty1", 0);
+	ASSERT_GE(mem_fd_empty1, 0);
+
+	mem_fd_data2 = memfd_create("data2", 0);
+	ASSERT_GE(mem_fd_data2, 0);
+	ASSERT_EQ(write(mem_fd_data2, data2, strlen(data2)), strlen(data2));
+
+	mem_fd_empty2 = memfd_create("empty2", 0);
+	ASSERT_GE(mem_fd_empty2, 0);
+
+	ASSERT_EQ(preserve_fd(session_fd1, mem_fd_data1, 0x1111), 0);
+	ASSERT_EQ(preserve_fd(session_fd1, mem_fd_empty1, 0x2222), 0);
+	ASSERT_EQ(preserve_fd(session_fd2, mem_fd_data2, 0x3333), 0);
+	ASSERT_EQ(preserve_fd(session_fd2, mem_fd_empty2, 0x4444), 0);
+
+	ASSERT_EQ(lseek(mem_fd_data1, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd_data1, read_buf, sizeof(read_buf)), strlen(data1));
+	ASSERT_STREQ(read_buf, data1);
+
+	memset(read_buf, 0, sizeof(read_buf));
+	ASSERT_EQ(lseek(mem_fd_data2, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd_data2, read_buf, sizeof(read_buf)), strlen(data2));
+	ASSERT_STREQ(read_buf, data2);
+
+	ASSERT_EQ(lseek(mem_fd_empty1, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd_empty1, read_buf, sizeof(read_buf)), 0);
+
+	ASSERT_EQ(lseek(mem_fd_empty2, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd_empty2, read_buf, sizeof(read_buf)), 0);
+
+	ASSERT_EQ(close(mem_fd_data1), 0);
+	ASSERT_EQ(close(mem_fd_empty1), 0);
+	ASSERT_EQ(close(mem_fd_data2), 0);
+	ASSERT_EQ(close(mem_fd_empty2), 0);
+	ASSERT_EQ(close(session_fd1), 0);
+	ASSERT_EQ(close(session_fd2), 0);
+}
+
+/*
+ * Test Case: Preserve Unsupported File Descriptor
+ *
+ * Verifies that attempting to preserve a file descriptor that does not have
+ * a registered Live Update handler fails gracefully.
+ * Uses /dev/null as a representative of a file type (character device)
+ * that is not supported by the orchestrator.
+ */
+TEST_F(liveupdate_device, preserve_unsupported_fd)
+{
+	int session_fd, unsupported_fd;
+	int ret;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd = create_session(self->fd1, "unsupported-fd-test");
+	ASSERT_GE(session_fd, 0);
+
+	unsupported_fd = open("/dev/null", O_RDWR);
+	ASSERT_GE(unsupported_fd, 0);
+
+	ret = preserve_fd(session_fd, unsupported_fd, 0xDEAD);
+	EXPECT_EQ(ret, -ENOENT);
+
+	ASSERT_EQ(close(unsupported_fd), 0);
+	ASSERT_EQ(close(session_fd), 0);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/liveupdate/luo_kexec_simple.c b/tools/testing/selftests/liveupdate/luo_kexec_simple.c
new file mode 100644
index 000000000000..d7ac1f3dc4cb
--- /dev/null
+++ b/tools/testing/selftests/liveupdate/luo_kexec_simple.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Copyright (c) 2025, Google LLC.
+ * Pasha Tatashin <pasha.tatashin@soleen.com>
+ *
+ * A simple selftest to validate the end-to-end lifecycle of a LUO session
+ * across a single kexec reboot.
+ */
+
+#include "luo_test_utils.h"
+
+#define TEST_SESSION_NAME "test-session"
+#define TEST_MEMFD_TOKEN 0x1A
+#define TEST_MEMFD_DATA "hello kexec world"
+
+/* Constants for the state-tracking mechanism, specific to this test file. */
+#define STATE_SESSION_NAME "kexec_simple_state"
+#define STATE_MEMFD_TOKEN 999
+
+/* Stage 1: Executed before the kexec reboot. */
+static void run_stage_1(int luo_fd)
+{
+	int session_fd;
+
+	ksft_print_msg("[STAGE 1] Starting pre-kexec setup...\n");
+
+	ksft_print_msg("[STAGE 1] Creating state file for next stage (2)...\n");
+	create_state_file(luo_fd, STATE_SESSION_NAME, STATE_MEMFD_TOKEN, 2);
+
+	ksft_print_msg("[STAGE 1] Creating session '%s' and preserving memfd...\n",
+		       TEST_SESSION_NAME);
+	session_fd = luo_create_session(luo_fd, TEST_SESSION_NAME);
+	if (session_fd < 0)
+		fail_exit("luo_create_session for '%s'", TEST_SESSION_NAME);
+
+	if (create_and_preserve_memfd(session_fd, TEST_MEMFD_TOKEN,
+				      TEST_MEMFD_DATA) < 0) {
+		fail_exit("create_and_preserve_memfd for token %#x",
+			  TEST_MEMFD_TOKEN);
+	}
+
+	close(luo_fd);
+	daemonize_and_wait();
+}
+
+/* Stage 2: Executed after the kexec reboot. */
+static void run_stage_2(int luo_fd, int state_session_fd)
+{
+	int session_fd, mfd, stage;
+
+	ksft_print_msg("[STAGE 2] Starting post-kexec verification...\n");
+
+	restore_and_read_stage(state_session_fd, STATE_MEMFD_TOKEN, &stage);
+	if (stage != 2)
+		fail_exit("Expected stage 2, but state file contains %d", stage);
+
+	ksft_print_msg("[STAGE 2] Retrieving session '%s'...\n", TEST_SESSION_NAME);
+	session_fd = luo_retrieve_session(luo_fd, TEST_SESSION_NAME);
+	if (session_fd < 0)
+		fail_exit("luo_retrieve_session for '%s'", TEST_SESSION_NAME);
+
+	ksft_print_msg("[STAGE 2] Restoring and verifying memfd (token %#x)...\n",
+		       TEST_MEMFD_TOKEN);
+	mfd = restore_and_verify_memfd(session_fd, TEST_MEMFD_TOKEN,
+				       TEST_MEMFD_DATA);
+	if (mfd < 0)
+		fail_exit("restore_and_verify_memfd for token %#x", TEST_MEMFD_TOKEN);
+	close(mfd);
+
+	ksft_print_msg("[STAGE 2] Test data verified successfully.\n");
+	ksft_print_msg("[STAGE 2] Finalizing test session...\n");
+	if (luo_session_finish(session_fd) < 0)
+		fail_exit("luo_session_finish for test session");
+	close(session_fd);
+
+	ksft_print_msg("[STAGE 2] Finalizing state session...\n");
+	if (luo_session_finish(state_session_fd) < 0)
+		fail_exit("luo_session_finish for state session");
+	close(state_session_fd);
+
+	ksft_print_msg("\n--- SIMPLE KEXEC TEST PASSED ---\n");
+}
+
+int main(int argc, char *argv[])
+{
+	return luo_test(argc, argv, STATE_SESSION_NAME,
+			run_stage_1, run_stage_2);
+}
diff --git a/tools/testing/selftests/liveupdate/luo_multi_session.c b/tools/testing/selftests/liveupdate/luo_multi_session.c
new file mode 100644
index 000000000000..0ee2d795beef
--- /dev/null
+++ b/tools/testing/selftests/liveupdate/luo_multi_session.c
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Copyright (c) 2025, Google LLC.
+ * Pasha Tatashin <pasha.tatashin@soleen.com>
+ *
+ * A selftest to validate the end-to-end lifecycle of multiple LUO sessions
+ * across a kexec reboot, including empty sessions and sessions with multiple
+ * files.
+ */
+
+#include "luo_test_utils.h"
+
+#define SESSION_EMPTY_1 "multi-test-empty-1"
+#define SESSION_EMPTY_2 "multi-test-empty-2"
+#define SESSION_FILES_1 "multi-test-files-1"
+#define SESSION_FILES_2 "multi-test-files-2"
+
+#define MFD1_TOKEN 0x1001
+#define MFD2_TOKEN 0x2002
+#define MFD3_TOKEN 0x3003
+
+#define MFD1_DATA "Data for session files 1"
+#define MFD2_DATA "First file for session files 2"
+#define MFD3_DATA "Second file for session files 2"
+
+#define STATE_SESSION_NAME "kexec_multi_state"
+#define STATE_MEMFD_TOKEN 998
+
+/* Stage 1: Executed before the kexec reboot. */
+static void run_stage_1(int luo_fd)
+{
+	int s_empty1_fd, s_empty2_fd, s_files1_fd, s_files2_fd;
+
+	ksft_print_msg("[STAGE 1] Starting pre-kexec setup for multi-session test...\n");
+
+	ksft_print_msg("[STAGE 1] Creating state file for next stage (2)...\n");
+	create_state_file(luo_fd, STATE_SESSION_NAME, STATE_MEMFD_TOKEN, 2);
+
+	ksft_print_msg("[STAGE 1] Creating empty sessions '%s' and '%s'...\n",
+		       SESSION_EMPTY_1, SESSION_EMPTY_2);
+	s_empty1_fd = luo_create_session(luo_fd, SESSION_EMPTY_1);
+	if (s_empty1_fd < 0)
+		fail_exit("luo_create_session for '%s'", SESSION_EMPTY_1);
+
+	s_empty2_fd = luo_create_session(luo_fd, SESSION_EMPTY_2);
+	if (s_empty2_fd < 0)
+		fail_exit("luo_create_session for '%s'", SESSION_EMPTY_2);
+
+	ksft_print_msg("[STAGE 1] Creating session '%s' with one memfd...\n",
+		       SESSION_FILES_1);
+
+	s_files1_fd = luo_create_session(luo_fd, SESSION_FILES_1);
+	if (s_files1_fd < 0)
+		fail_exit("luo_create_session for '%s'", SESSION_FILES_1);
+	if (create_and_preserve_memfd(s_files1_fd, MFD1_TOKEN, MFD1_DATA) < 0) {
+		fail_exit("create_and_preserve_memfd for token %#x",
+			  MFD1_TOKEN);
+	}
+
+	ksft_print_msg("[STAGE 1] Creating session '%s' with two memfds...\n",
+		       SESSION_FILES_2);
+
+	s_files2_fd = luo_create_session(luo_fd, SESSION_FILES_2);
+	if (s_files2_fd < 0)
+		fail_exit("luo_create_session for '%s'", SESSION_FILES_2);
+	if (create_and_preserve_memfd(s_files2_fd, MFD2_TOKEN, MFD2_DATA) < 0) {
+		fail_exit("create_and_preserve_memfd for token %#x",
+			  MFD2_TOKEN);
+	}
+	if (create_and_preserve_memfd(s_files2_fd, MFD3_TOKEN, MFD3_DATA) < 0) {
+		fail_exit("create_and_preserve_memfd for token %#x",
+			  MFD3_TOKEN);
+	}
+
+	close(luo_fd);
+	daemonize_and_wait();
+}
+
+/* Stage 2: Executed after the kexec reboot. */
+static void run_stage_2(int luo_fd, int state_session_fd)
+{
+	int s_empty1_fd, s_empty2_fd, s_files1_fd, s_files2_fd;
+	int mfd1, mfd2, mfd3, stage;
+
+	ksft_print_msg("[STAGE 2] Starting post-kexec verification...\n");
+
+	restore_and_read_stage(state_session_fd, STATE_MEMFD_TOKEN, &stage);
+	if (stage != 2) {
+		fail_exit("Expected stage 2, but state file contains %d",
+			  stage);
+	}
+
+	ksft_print_msg("[STAGE 2] Retrieving all sessions...\n");
+	s_empty1_fd = luo_retrieve_session(luo_fd, SESSION_EMPTY_1);
+	if (s_empty1_fd < 0)
+		fail_exit("luo_retrieve_session for '%s'", SESSION_EMPTY_1);
+
+	s_empty2_fd = luo_retrieve_session(luo_fd, SESSION_EMPTY_2);
+	if (s_empty2_fd < 0)
+		fail_exit("luo_retrieve_session for '%s'", SESSION_EMPTY_2);
+
+	s_files1_fd = luo_retrieve_session(luo_fd, SESSION_FILES_1);
+	if (s_files1_fd < 0)
+		fail_exit("luo_retrieve_session for '%s'", SESSION_FILES_1);
+
+	s_files2_fd = luo_retrieve_session(luo_fd, SESSION_FILES_2);
+	if (s_files2_fd < 0)
+		fail_exit("luo_retrieve_session for '%s'", SESSION_FILES_2);
+
+	ksft_print_msg("[STAGE 2] Verifying contents of session '%s'...\n",
+		       SESSION_FILES_1);
+	mfd1 = restore_and_verify_memfd(s_files1_fd, MFD1_TOKEN, MFD1_DATA);
+	if (mfd1 < 0)
+		fail_exit("restore_and_verify_memfd for token %#x", MFD1_TOKEN);
+	close(mfd1);
+
+	ksft_print_msg("[STAGE 2] Verifying contents of session '%s'...\n",
+		       SESSION_FILES_2);
+
+	mfd2 = restore_and_verify_memfd(s_files2_fd, MFD2_TOKEN, MFD2_DATA);
+	if (mfd2 < 0)
+		fail_exit("restore_and_verify_memfd for token %#x", MFD2_TOKEN);
+	close(mfd2);
+
+	mfd3 = restore_and_verify_memfd(s_files2_fd, MFD3_TOKEN, MFD3_DATA);
+	if (mfd3 < 0)
+		fail_exit("restore_and_verify_memfd for token %#x", MFD3_TOKEN);
+	close(mfd3);
+
+	ksft_print_msg("[STAGE 2] Test data verified successfully.\n");
+
+	ksft_print_msg("[STAGE 2] Finalizing all test sessions...\n");
+	if (luo_session_finish(s_empty1_fd) < 0)
+		fail_exit("luo_session_finish for '%s'", SESSION_EMPTY_1);
+	close(s_empty1_fd);
+
+	if (luo_session_finish(s_empty2_fd) < 0)
+		fail_exit("luo_session_finish for '%s'", SESSION_EMPTY_2);
+	close(s_empty2_fd);
+
+	if (luo_session_finish(s_files1_fd) < 0)
+		fail_exit("luo_session_finish for '%s'", SESSION_FILES_1);
+	close(s_files1_fd);
+
+	if (luo_session_finish(s_files2_fd) < 0)
+		fail_exit("luo_session_finish for '%s'", SESSION_FILES_2);
+	close(s_files2_fd);
+
+	ksft_print_msg("[STAGE 2] Finalizing state session...\n");
+	if (luo_session_finish(state_session_fd) < 0)
+		fail_exit("luo_session_finish for state session");
+	close(state_session_fd);
+
+	ksft_print_msg("\n--- MULTI-SESSION KEXEC TEST PASSED ---\n");
+}
+
+int main(int argc, char *argv[])
+{
+	return luo_test(argc, argv, STATE_SESSION_NAME,
+			run_stage_1, run_stage_2);
+}
diff --git a/tools/testing/selftests/liveupdate/luo_test_utils.c b/tools/testing/selftests/liveupdate/luo_test_utils.c
new file mode 100644
index 000000000000..3c8721c505df
--- /dev/null
+++ b/tools/testing/selftests/liveupdate/luo_test_utils.c
@@ -0,0 +1,266 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Copyright (c) 2025, Google LLC.
+ * Pasha Tatashin <pasha.tatashin@soleen.com>
+ */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <getopt.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <stdarg.h>
+
+#include "luo_test_utils.h"
+
+int luo_open_device(void)
+{
+	return open(LUO_DEVICE, O_RDWR);
+}
+
+int luo_create_session(int luo_fd, const char *name)
+{
+	struct liveupdate_ioctl_create_session arg = { .size = sizeof(arg) };
+
+	snprintf((char *)arg.name, LIVEUPDATE_SESSION_NAME_LENGTH, "%.*s",
+		 LIVEUPDATE_SESSION_NAME_LENGTH - 1, name);
+
+	if (ioctl(luo_fd, LIVEUPDATE_IOCTL_CREATE_SESSION, &arg) < 0)
+		return -errno;
+
+	return arg.fd;
+}
+
+int luo_retrieve_session(int luo_fd, const char *name)
+{
+	struct liveupdate_ioctl_retrieve_session arg = { .size = sizeof(arg) };
+
+	snprintf((char *)arg.name, LIVEUPDATE_SESSION_NAME_LENGTH, "%.*s",
+		 LIVEUPDATE_SESSION_NAME_LENGTH - 1, name);
+
+	if (ioctl(luo_fd, LIVEUPDATE_IOCTL_RETRIEVE_SESSION, &arg) < 0)
+		return -errno;
+
+	return arg.fd;
+}
+
+int create_and_preserve_memfd(int session_fd, int token, const char *data)
+{
+	struct liveupdate_session_preserve_fd arg = { .size = sizeof(arg) };
+	long page_size = sysconf(_SC_PAGE_SIZE);
+	void *map = MAP_FAILED;
+	int mfd = -1, ret = -1;
+
+	mfd = memfd_create("test_mfd", 0);
+	if (mfd < 0)
+		return -errno;
+
+	if (ftruncate(mfd, page_size) != 0)
+		goto out;
+
+	map = mmap(NULL, page_size, PROT_WRITE, MAP_SHARED, mfd, 0);
+	if (map == MAP_FAILED)
+		goto out;
+
+	snprintf(map, page_size, "%s", data);
+	munmap(map, page_size);
+
+	arg.fd = mfd;
+	arg.token = token;
+	if (ioctl(session_fd, LIVEUPDATE_SESSION_PRESERVE_FD, &arg) < 0)
+		goto out;
+
+	ret = 0;
+out:
+	if (ret != 0 && errno != 0)
+		ret = -errno;
+	if (mfd >= 0)
+		close(mfd);
+	return ret;
+}
+
+int restore_and_verify_memfd(int session_fd, int token,
+			     const char *expected_data)
+{
+	struct liveupdate_session_retrieve_fd arg = { .size = sizeof(arg) };
+	long page_size = sysconf(_SC_PAGE_SIZE);
+	void *map = MAP_FAILED;
+	int mfd = -1, ret = -1;
+
+	arg.token = token;
+	if (ioctl(session_fd, LIVEUPDATE_SESSION_RETRIEVE_FD, &arg) < 0)
+		return -errno;
+	mfd = arg.fd;
+
+	map = mmap(NULL, page_size, PROT_READ, MAP_SHARED, mfd, 0);
+	if (map == MAP_FAILED)
+		goto out;
+
+	if (expected_data && strcmp(expected_data, map) != 0) {
+		ksft_print_msg("Data mismatch! Expected '%s', Got '%s'\n",
+			       expected_data, (char *)map);
+		ret = -EINVAL;
+		goto out_munmap;
+	}
+
+	ret = mfd;
+out_munmap:
+	munmap(map, page_size);
+out:
+	if (ret < 0 && errno != 0)
+		ret = -errno;
+	if (ret < 0 && mfd >= 0)
+		close(mfd);
+	return ret;
+}
+
+int luo_session_finish(int session_fd)
+{
+	struct liveupdate_session_finish arg = { .size = sizeof(arg) };
+
+	if (ioctl(session_fd, LIVEUPDATE_SESSION_FINISH, &arg) < 0)
+		return -errno;
+
+	return 0;
+}
+
+void create_state_file(int luo_fd, const char *session_name, int token,
+		       int next_stage)
+{
+	char buf[32];
+	int state_session_fd;
+
+	state_session_fd = luo_create_session(luo_fd, session_name);
+	if (state_session_fd < 0)
+		fail_exit("luo_create_session for state tracking");
+
+	snprintf(buf, sizeof(buf), "%d", next_stage);
+	if (create_and_preserve_memfd(state_session_fd, token, buf) < 0)
+		fail_exit("create_and_preserve_memfd for state tracking");
+
+	/*
+	 * DO NOT close session FD, otherwise it is going to be unpreserved
+	 */
+}
+
+void restore_and_read_stage(int state_session_fd, int token, int *stage)
+{
+	char buf[32] = {0};
+	int mfd;
+
+	mfd = restore_and_verify_memfd(state_session_fd, token, NULL);
+	if (mfd < 0)
+		fail_exit("failed to restore state memfd");
+
+	if (read(mfd, buf, sizeof(buf) - 1) < 0)
+		fail_exit("failed to read state mfd");
+
+	*stage = atoi(buf);
+
+	close(mfd);
+}
+
+void daemonize_and_wait(void)
+{
+	pid_t pid;
+
+	ksft_print_msg("[STAGE 1] Forking persistent child to hold sessions...\n");
+
+	pid = fork();
+	if (pid < 0)
+		fail_exit("fork failed");
+
+	if (pid > 0) {
+		ksft_print_msg("[STAGE 1] Child PID: %d. Resources are pinned.\n", pid);
+		ksft_print_msg("[STAGE 1] You may now perform kexec reboot.\n");
+		exit(EXIT_SUCCESS);
+	}
+
+	/* Detach from terminal so closing the window doesn't kill us */
+	if (setsid() < 0)
+		fail_exit("setsid failed");
+
+	close(STDIN_FILENO);
+	close(STDOUT_FILENO);
+	close(STDERR_FILENO);
+
+	/* Change dir to root to avoid locking filesystems */
+	if (chdir("/") < 0)
+		exit(EXIT_FAILURE);
+
+	while (1)
+		sleep(60);
+}
+
+static int parse_stage_args(int argc, char *argv[])
+{
+	static struct option long_options[] = {
+		{"stage", required_argument, 0, 's'},
+		{0, 0, 0, 0}
+	};
+	int option_index = 0;
+	int stage = 1;
+	int opt;
+
+	optind = 1;
+	while ((opt = getopt_long(argc, argv, "s:", long_options, &option_index)) != -1) {
+		switch (opt) {
+		case 's':
+			stage = atoi(optarg);
+			if (stage != 1 && stage != 2)
+				fail_exit("Invalid stage argument");
+			break;
+		default:
+			fail_exit("Unknown argument");
+		}
+	}
+	return stage;
+}
+
+int luo_test(int argc, char *argv[],
+	     const char *state_session_name,
+	     luo_test_stage1_fn stage1,
+	     luo_test_stage2_fn stage2)
+{
+	int target_stage = parse_stage_args(argc, argv);
+	int luo_fd = luo_open_device();
+	int state_session_fd;
+	int detected_stage;
+
+	if (luo_fd < 0) {
+		ksft_exit_skip("Failed to open %s. Is the luo module loaded?\n",
+			       LUO_DEVICE);
+	}
+
+	state_session_fd = luo_retrieve_session(luo_fd, state_session_name);
+	if (state_session_fd == -ENOENT)
+		detected_stage = 1;
+	else if (state_session_fd >= 0)
+		detected_stage = 2;
+	else
+		fail_exit("Failed to check for state session");
+
+	if (target_stage != detected_stage) {
+		ksft_exit_fail_msg("Stage mismatch Requested --stage %d, but system is in stage %d.\n"
+				   "(State session %s: %s)\n",
+				   target_stage, detected_stage, state_session_name,
+				   (detected_stage == 2) ? "EXISTS" : "MISSING");
+	}
+
+	if (target_stage == 1)
+		stage1(luo_fd);
+	else
+		stage2(luo_fd, state_session_fd);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/liveupdate/luo_test_utils.h b/tools/testing/selftests/liveupdate/luo_test_utils.h
new file mode 100644
index 000000000000..90099bf49577
--- /dev/null
+++ b/tools/testing/selftests/liveupdate/luo_test_utils.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Copyright (c) 2025, Google LLC.
+ * Pasha Tatashin <pasha.tatashin@soleen.com>
+ *
+ * Utility functions for LUO kselftests.
+ */
+
+#ifndef LUO_TEST_UTILS_H
+#define LUO_TEST_UTILS_H
+
+#include <errno.h>
+#include <string.h>
+#include <linux/liveupdate.h>
+#include "../kselftest.h"
+
+#define LUO_DEVICE "/dev/liveupdate"
+
+#define fail_exit(fmt, ...)						\
+	ksft_exit_fail_msg("[%s:%d] " fmt " (errno: %s)\n",	\
+			   __func__, __LINE__, ##__VA_ARGS__, strerror(errno))
+
+int luo_open_device(void);
+int luo_create_session(int luo_fd, const char *name);
+int luo_retrieve_session(int luo_fd, const char *name);
+int luo_session_finish(int session_fd);
+
+int create_and_preserve_memfd(int session_fd, int token, const char *data);
+int restore_and_verify_memfd(int session_fd, int token, const char *expected_data);
+
+void create_state_file(int luo_fd, const char *session_name, int token,
+		       int next_stage);
+void restore_and_read_stage(int state_session_fd, int token, int *stage);
+
+void daemonize_and_wait(void);
+
+typedef void (*luo_test_stage1_fn)(int luo_fd);
+typedef void (*luo_test_stage2_fn)(int luo_fd, int state_session_fd);
+
+int luo_test(int argc, char *argv[], const char *state_session_name,
+	     luo_test_stage1_fn stage1, luo_test_stage2_fn stage2);
+
+#endif /* LUO_TEST_UTILS_H */