[v2,7/7] kstate, test: add test module for testing kstate subsystem.

Commit Message

Andrey Ryabinin March 10, 2025, 12:03 p.m. UTC

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 <[e-mail]>
---
 include/linux/kstate.h |  3 ++
 kernel/kstate.c        |  5 +++
 lib/Makefile           |  2 +
 lib/test_kstate.c      | 86 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 96 insertions(+)
 create mode 100644 lib/test_kstate.c

Patch

diff --git a/include/linux/kstate.h b/include/linux/kstate.h
index 36cfefd87572..0bde76aa4d8f 100644
--- a/include/linux/kstate.h
+++ b/include/linux/kstate.h
@@ -90,6 +90,7 @@  struct kstate_field {
 enum kstate_ids {
 	KSTATE_RSVD_MEM_ID = 1,
 	KSTATE_STRUCT_PAGE_ID,
+	KSTATE_TEST_ID,
 	KSTATE_LAST_ID = -1,
 };
 
@@ -132,6 +133,8 @@  extern struct kstate_description page_state;
 
 void kstate_init(void);
 
+bool is_kstate_kernel(void);
+
 int kstate_save_state(void);
 void free_kstate_stream(void);
 
diff --git a/kernel/kstate.c b/kernel/kstate.c
index 68a1272abceb..3d9b786da72a 100644
--- a/kernel/kstate.c
+++ b/kernel/kstate.c
@@ -287,6 +287,11 @@  static void restore_migrate_state(unsigned long kstate_data,
 static unsigned long kstate_stream_addr = -1;
 static unsigned long kstate_size;
 
+bool is_kstate_kernel(void)
+{
+	return kstate_stream_addr != -1;
+}
+
 static void __kstate_register(struct kstate_description *state, void *obj,
 			struct state_entry *se)
 {
diff --git a/lib/Makefile b/lib/Makefile
index d5cfc7afbbb8..1395b852b58d 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -356,6 +356,8 @@  obj-$(CONFIG_PARMAN) += parman.o
 
 obj-y += group_cpus.o
 
+obj-$(CONFIG_KSTATE) += test_kstate.o
+
 # GCC library routines
 obj-$(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..1d9feb017415
--- /dev/null
+++ b/lib/test_kstate.c
@@ -0,0 +1,86 @@ 
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/io.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 page *page;
+};
+
+struct kstate_description test_state = {
+	.name = "test",
+	.version_id = 1,
+	.id = KSTATE_TEST_ID,
+	.state_list = LIST_HEAD_INIT(test_state.state_list),
+	.fields = (const struct kstate_field[]) {
+		KSTATE_BASE_TYPE(i, struct kstate_test_data, int),
+		KSTATE_BASE_TYPE(s, struct kstate_test_data, char [10]),
+		KSTATE_POINTER(p_ulong, struct kstate_test_data),
+		KSTATE_PAGE(page, struct kstate_test_data),
+		KSTATE_END_OF_LIST()
+	},
+};
+
+static struct kstate_test_data test_data;
+
+static int init_test_data(void)
+{
+	struct page *page;
+	int i;
+
+	test_data.i = 10;
+	ulong_val = 20;
+	memcpy(test_data.s, "abcdefghk", sizeof(test_data.s));
+	page = alloc_page(GFP_KERNEL);
+	if (!page)
+		return -ENOMEM;
+
+	for (i = 0; i < PAGE_SIZE/4; i += 4)
+		*((u32 *)page_address(page) + i) = 0xdeadbeef;
+	test_data.page = page;
+	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 < PAGE_SIZE/4; i += 4) {
+		u32 val = *((u32 *)page_address(test_data.page) + i);
+
+		WARN_ON(val != 0xdeadbeef);
+	}
+}
+
+static int __init test_kstate_init(void)
+{
+	int ret = 0;
+
+	test_data.p_ulong = &ulong_val;
+
+	if (!is_kstate_kernel()) {
+		ret = init_test_data();
+		if (ret)
+			goto out;
+	}
+
+	kstate_register(&test_state, &test_data);
+
+	validate_test_data();
+
+out:
+	return ret;
+}
+__initcall(test_kstate_init);