selftests/liveupdate: Move luo_test_utils.* into a reusable library

Move luo_test_utils.[ch] into a lib/ directory and make libliveupdate
library. Pull the rules to build them out into a separate
libliveupdate.mk script. This will enable these utilities to be
also built by and used within other selftests (such as VFIO).

Update path in vmtest.sh as that one uses hardcoded path for util.

No functional change intended.

Co-developed-by: David Matlack <dmatlack@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Acked-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Vipin Sharma <vipinsh@google.com>
Link: https://patch.msgid.link/20260720203202.1964557-3-vipinsh@google.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

tools/testing/selftests/liveupdate/.gitignore

@@ -3,6 +3,7 @@
 !/**/
 !*.c
 !*.h
+!*.mk
 !*.sh
 !.gitignore
 !config

tools/testing/selftests/liveupdate/Makefile

@@ -1,7 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
-LIB_C += luo_test_utils.c
-
 TEST_GEN_PROGS += liveupdate
 
 TEST_GEN_PROGS_EXTENDED += luo_kexec_simple
@@ -12,25 +10,21 @@ TEST_GEN_PROGS_EXTENDED += luo_stress_files
 TEST_FILES += do_kexec.sh
 
 include ../lib.mk
+include lib/libliveupdate.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, $(LIBLIVEUPDATE_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 $(LIBLIVEUPDATE_O)
+	$(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $(TARGET_ARCH) $< $(LIBLIVEUPDATE_O) $(LDLIBS) -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)

tools/testing/selftests/liveupdate/lib/include/libliveupdate.h

@@ -7,13 +7,13 @@
  * Utility functions for LUO kselftests.
  */
 
-#ifndef LUO_TEST_UTILS_H
-#define LUO_TEST_UTILS_H
+#ifndef SELFTESTS_LIVEUPDATE_LIB_LIVEUPDATE_H
+#define SELFTESTS_LIVEUPDATE_LIB_LIVEUPDATE_H
 
 #include <errno.h>
 #include <string.h>
 #include <linux/liveupdate.h>
-#include "../kselftest.h"
+#include "../../../kselftest.h"
 
 #define LUO_DEVICE "/dev/liveupdate"
 
@@ -46,4 +46,4 @@ 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 */
+#endif /* SELFTESTS_LIVEUPDATE_LIB_LIVEUPDATE_H */

tools/testing/selftests/liveupdate/lib/libliveupdate.mk

@@ -0,0 +1,20 @@
+include $(top_srcdir)/scripts/subarch.include
+ARCH ?= $(SUBARCH)
+
+LIBLIVEUPDATE_SRCDIR := $(selfdir)/liveupdate/lib
+
+LIBLIVEUPDATE_C := lu_utils.c
+
+LIBLIVEUPDATE_OUTPUT := $(OUTPUT)/libliveupdate
+
+LIBLIVEUPDATE_O := $(patsubst %.c, $(LIBLIVEUPDATE_OUTPUT)/%.o, $(LIBLIVEUPDATE_C))
+
+CFLAGS += -I$(LIBLIVEUPDATE_SRCDIR)/include
+
+$(LIBLIVEUPDATE_OUTPUT):
+	$(Q)mkdir -p $@
+
+$(LIBLIVEUPDATE_O): $(LIBLIVEUPDATE_OUTPUT)/%.o : $(LIBLIVEUPDATE_SRCDIR)/%.c | $(LIBLIVEUPDATE_OUTPUT)
+	$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o $@
+
+EXTRA_CLEAN += $(LIBLIVEUPDATE_OUTPUT)

tools/testing/selftests/liveupdate/lib/lu_utils.c

@@ -23,7 +23,7 @@
 #include <stdarg.h>
 #include <linux/unistd.h>
 
-#include "luo_test_utils.h"
+#include <libliveupdate.h>
 
 int luo_open_device(void)
 {

tools/testing/selftests/liveupdate/liveupdate.c

@@ -24,9 +24,9 @@
 #include <sys/ioctl.h>
 #include <unistd.h>
 
+#include <libliveupdate.h>
 #include <linux/liveupdate.h>
 
-#include "luo_test_utils.h"
 #include "../kselftest.h"
 #include "../kselftest_harness.h"
 

tools/testing/selftests/liveupdate/luo_kexec_simple.c

@@ -8,7 +8,7 @@
  * across a single kexec reboot.
  */
 
-#include "luo_test_utils.h"
+#include <libliveupdate.h>
 
 #define TEST_SESSION_NAME "test-session"
 #define TEST_MEMFD_TOKEN 0x1A

tools/testing/selftests/liveupdate/luo_multi_session.c

@@ -9,7 +9,7 @@
  * files.
  */
 
-#include "luo_test_utils.h"
+#include <libliveupdate.h>
 
 #define SESSION_EMPTY_1 "multi-test-empty-1"
 #define SESSION_EMPTY_2 "multi-test-empty-2"

tools/testing/selftests/liveupdate/luo_stress_files.c

@@ -10,7 +10,8 @@
 
 #include <stdio.h>
 #include <unistd.h>
-#include "luo_test_utils.h"
+
+#include <libliveupdate.h>
 
 #define NUM_FILES 500
 #define STATE_SESSION_NAME "kexec_many_files_state"

tools/testing/selftests/liveupdate/luo_stress_sessions.c

@@ -10,7 +10,8 @@
 
 #include <stdio.h>
 #include <unistd.h>
-#include "luo_test_utils.h"
+
+#include <libliveupdate.h>
 
 #define NUM_SESSIONS 2000
 #define STATE_SESSION_NAME "kexec_many_state"

tools/testing/selftests/liveupdate/vmtest.sh

@@ -131,9 +131,9 @@ function mkinitrd() {
 	"$CROSS_COMPILE"gcc -static -O2 -nostdinc -nostdlib \
 		-I "$headers_dir/include" \
 		-I "$kernel_dir/tools/include/nolibc" \
-		-I "$test_dir" \
+		-I "$test_dir/lib/include" \
 		-o "$workspace_dir/test_binary" \
-		"$test_dir/$test_name.c" "$test_dir/luo_test_utils.c"
+		"$test_dir/$test_name.c" "$test_dir/lib/lu_utils.c"
 
 	"$CROSS_COMPILE"gcc -s -static -Os -nostdinc -nostdlib		\
 			-fno-asynchronous-unwind-tables -fno-ident	\