[PATCH v3 5/7] kstate, test: add test module for testing kstate subsystem.

[Andrey Ryabinin <arbn@yandex-team.com>]

This is simple test and playground useful kstate subsystem development.
It contains some structure with different kind of data which migrated
across kexec to the new kernel using kstate.

Signed-off-by: Andrey Ryabinin <arbn@yandex-team.com>
---
 MAINTAINERS               |   1 +
 include/linux/kstate.h    |   2 +
 kernel/liveupdate/Kconfig |   8 +++
 lib/Makefile              |   2 +
 lib/test_kstate.c         | 116 ++++++++++++++++++++++++++++++++++++++
 5 files changed, 129 insertions(+)
 create mode 100644 lib/test_kstate.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 2cd9e49abee5..e96da6d97e75 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13723,6 +13723,7 @@ M:	Andrey Ryabinin <ryabinin.a.a@gmail.com>
 S:	Maintained
 F:	include/linux/kstate.h
 F:	kernel/livupdate/kstate.c
+F:	lib/test_kstate.c
 
 KTD253 BACKLIGHT DRIVER
 M:	Linus Walleij <linus.walleij@linaro.org>
diff --git a/include/linux/kstate.h b/include/linux/kstate.h
index 5a95960e5b03..0ced0da37c8f 100644
--- a/include/linux/kstate.h
+++ b/include/linux/kstate.h
@@ -95,6 +95,8 @@ struct kstate_field {
 enum kstate_ids {
 	KSTATE_FOLIO_ID = 1,
 	KSTATE_KHO_FDT_ID,
+	KSTATE_TEST_ID,
+	KSTATE_TEST_ID_V2,
 	KSTATE_LAST_ID = -1,
 };
 
diff --git a/kernel/liveupdate/Kconfig b/kernel/liveupdate/Kconfig
index b6ea861006bf..af9a25bdcd6e 100644
--- a/kernel/liveupdate/Kconfig
+++ b/kernel/liveupdate/Kconfig
@@ -69,6 +69,14 @@ config KSTATE
 	  state, save it into the memory and restore the state after kexec
 	  in new kernel.
 
+config KSTATE_TEST
+	bool "KSTATE test code"
+	help
+	  Build a simple test/playground code that is useful for kstate
+	  subsystem development. It contains some structure with different
+	  kind of data which migrated across kexec to the new kernel
+	  using KSTATE.
+
 config KEXEC_HANDOVER
 	bool "kexec handover"
 	depends on ARCH_SUPPORTS_KEXEC_HANDOVER && ARCH_SUPPORTS_KEXEC_FILE
diff --git a/lib/Makefile b/lib/Makefile
index 392ff808c9b9..46616577caf3 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -316,6 +316,8 @@ obj-$(CONFIG_PARMAN) += parman.o
 
 obj-y += group_cpus.o
 
+obj-$(CONFIG_KSTATE_TEST) += test_kstate.o
+
 # GCC library routines
 obj-$(CONFIG_GENERIC_LIB_ASHLDI3) += ashldi3.o
 obj-$(CONFIG_GENERIC_LIB_ASHRDI3) += ashrdi3.o
diff --git a/lib/test_kstate.c b/lib/test_kstate.c
new file mode 100644
index 000000000000..70534e8c718f
--- /dev/null
+++ b/lib/test_kstate.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0
+#define pr_fmt(fmt) "kstate test: " fmt
+#include <linux/io.h>
+#include <linux/kexec_handover.h>
+#include <linux/kstate.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+
+static unsigned long ulong_val;
+struct kstate_test_data {
+	int i;
+	unsigned long *p_ulong;
+	char s[10];
+	struct folio *folio;
+};
+
+#define KSTATE_TEST_DATA_ID 123
+
+struct kstate_description test_state_v2 = {
+	.name = "test_v2",
+	.version_id = 1,
+	.id = KSTATE_TEST_ID_V2,
+	.fields = (const struct kstate_field[]) {
+		KSTATE_BASE_TYPE(i, struct kstate_test_data, int),
+		KSTATE_END_OF_LIST()
+	},
+};
+
+struct kstate_description test_state = {
+	.name = "test",
+	.version_id = 2,
+	.id = KSTATE_TEST_ID,
+	.fields = (const struct kstate_field[]) {
+		KSTATE_BASE_TYPE(s, struct kstate_test_data, char [10]),
+		KSTATE_POINTER(p_ulong, struct kstate_test_data),
+		KSTATE_FOLIO(folio, struct kstate_test_data),
+		KSTATE_BASE_TYPE_DEPRECATED(k, u16, 1),
+		KSTATE_END_OF_LIST()
+	},
+	.subsections = (const struct kstate_description *[]){
+		&test_state_v2,
+		NULL
+	},
+};
+
+static struct kstate_test_data test_data;
+
+static int init_test_data(void)
+{
+	struct folio *folio;
+	int i;
+
+	test_data.i = 10;
+	ulong_val = 20;
+	memcpy(test_data.s, "abcdefghk", sizeof(test_data.s));
+	folio = folio_alloc(GFP_KERNEL, 0);
+	if (!folio)
+		return -ENOMEM;
+
+	for (i = 0; i < folio_size(folio)/sizeof(u32); i += 4)
+		*((u32 *)folio_address(folio) + i) = 0xdeadbeef;
+	test_data.folio = folio;
+	return 0;
+}
+
+static void validate_test_data(void)
+{
+	int i;
+
+	if (WARN_ON(test_data.i != 10))
+		return;
+	if (WARN_ON(*test_data.p_ulong != 20))
+		return;
+	if (WARN_ON(strcmp(test_data.s, "abcdefghk") != 0))
+		return;
+
+	for (i = 0; i < folio_size(test_data.folio)/4; i += 4) {
+		u32 val = *((u32 *)folio_address(test_data.folio) + i);
+
+		if (WARN_ON_ONCE(val != 0xdeadbeef))
+			return;
+	}
+}
+
+static int __init test_kstate_init(void)
+{
+	int ret = 0;
+
+	test_data.p_ulong = &ulong_val;
+
+	ret = kstate_register(&test_state, &test_data, KSTATE_TEST_DATA_ID);
+	if (ret) {
+		pr_err("register failed %d\n", ret);
+		goto out;
+	}
+
+	if (!is_kho_boot()) {
+		ret = init_test_data();
+		if (ret)
+			goto out;
+	} else {
+		pr_info("restoring data\n");
+		ret = kstate_restore(&test_state, &test_data, KSTATE_TEST_DATA_ID);
+		if (ret) {
+			pr_err("restore failed %d\n", ret);
+			goto out;
+		}
+
+	}
+
+	validate_test_data();
+
+out:
+	return ret;
+}
+late_initcall(test_kstate_init);
-- 
2.49.1