x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 652 insertions, 0 deletions

diff --git a/drivers/base/test/property-entry-test.c b/drivers/base/test/property-entry-test.c
new file mode 100644
index 000000000..89cdfc2f8
--- /dev/null
+++ b/drivers/base/test/property-entry-test.c
@@ -0,0 +1,652 @@
+// SPDX-License-Identifier: GPL-2.0
+// Unit tests for property entries API
+//
+// Copyright 2019 Google LLC.
+
+#include <kunit/test.h>
+
+#include <linux/of.h>
+#include <linux/property.h>
+#include <linux/types.h>
+
+static void pe_test_uints(struct kunit *test)
+{
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U8("prop-u8", 8),
+		PROPERTY_ENTRY_U16("prop-u16", 16),
+		PROPERTY_ENTRY_U32("prop-u32", 32),
+		PROPERTY_ENTRY_U64("prop-u64", 64),
+		{ }
+	};
+
+	struct fwnode_handle *node;
+	u8 val_u8, array_u8[2];
+	u16 val_u16, array_u16[2];
+	u32 val_u32, array_u32[2];
+	u64 val_u64, array_u64[2];
+	int error;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	error = fwnode_property_count_u8(node, "prop-u8");
+	KUNIT_EXPECT_EQ(test, error, 1);
+
+	error = fwnode_property_read_u8(node, "prop-u8", &val_u8);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, val_u8, 8);
+
+	error = fwnode_property_read_u8_array(node, "prop-u8", array_u8, 1);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, array_u8[0], 8);
+
+	error = fwnode_property_read_u8_array(node, "prop-u8", array_u8, 2);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u8(node, "no-prop-u8", &val_u8);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u8_array(node, "no-prop-u8", array_u8, 1);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u16(node, "prop-u16", &val_u16);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, val_u16, 16);
+
+	error = fwnode_property_count_u16(node, "prop-u16");
+	KUNIT_EXPECT_EQ(test, error, 1);
+
+	error = fwnode_property_read_u16_array(node, "prop-u16", array_u16, 1);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, array_u16[0], 16);
+
+	error = fwnode_property_read_u16_array(node, "prop-u16", array_u16, 2);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u16(node, "no-prop-u16", &val_u16);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u16_array(node, "no-prop-u16", array_u16, 1);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u32(node, "prop-u32", &val_u32);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, val_u32, 32);
+
+	error = fwnode_property_count_u32(node, "prop-u32");
+	KUNIT_EXPECT_EQ(test, error, 1);
+
+	error = fwnode_property_read_u32_array(node, "prop-u32", array_u32, 1);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, array_u32[0], 32);
+
+	error = fwnode_property_read_u32_array(node, "prop-u32", array_u32, 2);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u32(node, "no-prop-u32", &val_u32);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u32_array(node, "no-prop-u32", array_u32, 1);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u64(node, "prop-u64", &val_u64);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, val_u64, 64);
+
+	error = fwnode_property_count_u64(node, "prop-u64");
+	KUNIT_EXPECT_EQ(test, error, 1);
+
+	error = fwnode_property_read_u64_array(node, "prop-u64", array_u64, 1);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, array_u64[0], 64);
+
+	error = fwnode_property_read_u64_array(node, "prop-u64", array_u64, 2);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u64(node, "no-prop-u64", &val_u64);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u64_array(node, "no-prop-u64", array_u64, 1);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	/* Count 64-bit values as 16-bit */
+	error = fwnode_property_count_u16(node, "prop-u64");
+	KUNIT_EXPECT_EQ(test, error, 4);
+
+	fwnode_remove_software_node(node);
+}
+
+static void pe_test_uint_arrays(struct kunit *test)
+{
+	static const u8 a_u8[10] = { 8, 9 };
+	static const u16 a_u16[10] = { 16, 17 };
+	static const u32 a_u32[10] = { 32, 33 };
+	static const u64 a_u64[10] = { 64, 65 };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U8_ARRAY("prop-u8", a_u8),
+		PROPERTY_ENTRY_U16_ARRAY("prop-u16", a_u16),
+		PROPERTY_ENTRY_U32_ARRAY("prop-u32", a_u32),
+		PROPERTY_ENTRY_U64_ARRAY("prop-u64", a_u64),
+		{ }
+	};
+
+	struct fwnode_handle *node;
+	u8 val_u8, array_u8[32];
+	u16 val_u16, array_u16[32];
+	u32 val_u32, array_u32[32];
+	u64 val_u64, array_u64[32];
+	int error;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	error = fwnode_property_read_u8(node, "prop-u8", &val_u8);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, val_u8, 8);
+
+	error = fwnode_property_count_u8(node, "prop-u8");
+	KUNIT_EXPECT_EQ(test, error, 10);
+
+	error = fwnode_property_read_u8_array(node, "prop-u8", array_u8, 1);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, array_u8[0], 8);
+
+	error = fwnode_property_read_u8_array(node, "prop-u8", array_u8, 2);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, array_u8[0], 8);
+	KUNIT_EXPECT_EQ(test, array_u8[1], 9);
+
+	error = fwnode_property_read_u8_array(node, "prop-u8", array_u8, 17);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u8(node, "no-prop-u8", &val_u8);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u8_array(node, "no-prop-u8", array_u8, 1);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u16(node, "prop-u16", &val_u16);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, val_u16, 16);
+
+	error = fwnode_property_count_u16(node, "prop-u16");
+	KUNIT_EXPECT_EQ(test, error, 10);
+
+	error = fwnode_property_read_u16_array(node, "prop-u16", array_u16, 1);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, array_u16[0], 16);
+
+	error = fwnode_property_read_u16_array(node, "prop-u16", array_u16, 2);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, array_u16[0], 16);
+	KUNIT_EXPECT_EQ(test, array_u16[1], 17);
+
+	error = fwnode_property_read_u16_array(node, "prop-u16", array_u16, 17);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u16(node, "no-prop-u16", &val_u16);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u16_array(node, "no-prop-u16", array_u16, 1);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u32(node, "prop-u32", &val_u32);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, val_u32, 32);
+
+	error = fwnode_property_count_u32(node, "prop-u32");
+	KUNIT_EXPECT_EQ(test, error, 10);
+
+	error = fwnode_property_read_u32_array(node, "prop-u32", array_u32, 1);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, array_u32[0], 32);
+
+	error = fwnode_property_read_u32_array(node, "prop-u32", array_u32, 2);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, array_u32[0], 32);
+	KUNIT_EXPECT_EQ(test, array_u32[1], 33);
+
+	error = fwnode_property_read_u32_array(node, "prop-u32", array_u32, 17);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u32(node, "no-prop-u32", &val_u32);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u32_array(node, "no-prop-u32", array_u32, 1);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u64(node, "prop-u64", &val_u64);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, val_u64, 64);
+
+	error = fwnode_property_count_u64(node, "prop-u64");
+	KUNIT_EXPECT_EQ(test, error, 10);
+
+	error = fwnode_property_read_u64_array(node, "prop-u64", array_u64, 1);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, array_u64[0], 64);
+
+	error = fwnode_property_read_u64_array(node, "prop-u64", array_u64, 2);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_EQ(test, array_u64[0], 64);
+	KUNIT_EXPECT_EQ(test, array_u64[1], 65);
+
+	error = fwnode_property_read_u64_array(node, "prop-u64", array_u64, 17);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u64(node, "no-prop-u64", &val_u64);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_u64_array(node, "no-prop-u64", array_u64, 1);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	/* Count 64-bit values as 16-bit */
+	error = fwnode_property_count_u16(node, "prop-u64");
+	KUNIT_EXPECT_EQ(test, error, 40);
+
+	/* Other way around */
+	error = fwnode_property_count_u64(node, "prop-u16");
+	KUNIT_EXPECT_EQ(test, error, 2);
+
+	fwnode_remove_software_node(node);
+}
+
+static void pe_test_strings(struct kunit *test)
+{
+	static const char *strings[] = {
+		"string-a",
+		"string-b",
+	};
+
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_STRING("str", "single"),
+		PROPERTY_ENTRY_STRING("empty", ""),
+		PROPERTY_ENTRY_STRING_ARRAY("strs", strings),
+		{ }
+	};
+
+	struct fwnode_handle *node;
+	const char *str;
+	const char *strs[10];
+	int error;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	error = fwnode_property_read_string(node, "str", &str);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_STREQ(test, str, "single");
+
+	error = fwnode_property_string_array_count(node, "str");
+	KUNIT_EXPECT_EQ(test, error, 1);
+
+	error = fwnode_property_read_string_array(node, "str", strs, 1);
+	KUNIT_EXPECT_EQ(test, error, 1);
+	KUNIT_EXPECT_STREQ(test, strs[0], "single");
+
+	/* asking for more data returns what we have */
+	error = fwnode_property_read_string_array(node, "str", strs, 2);
+	KUNIT_EXPECT_EQ(test, error, 1);
+	KUNIT_EXPECT_STREQ(test, strs[0], "single");
+
+	error = fwnode_property_read_string(node, "no-str", &str);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_read_string_array(node, "no-str", strs, 1);
+	KUNIT_EXPECT_LT(test, error, 0);
+
+	error = fwnode_property_read_string(node, "empty", &str);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_STREQ(test, str, "");
+
+	error = fwnode_property_string_array_count(node, "strs");
+	KUNIT_EXPECT_EQ(test, error, 2);
+
+	error = fwnode_property_read_string_array(node, "strs", strs, 3);
+	KUNIT_EXPECT_EQ(test, error, 2);
+	KUNIT_EXPECT_STREQ(test, strs[0], "string-a");
+	KUNIT_EXPECT_STREQ(test, strs[1], "string-b");
+
+	error = fwnode_property_read_string_array(node, "strs", strs, 1);
+	KUNIT_EXPECT_EQ(test, error, 1);
+	KUNIT_EXPECT_STREQ(test, strs[0], "string-a");
+
+	/* NULL argument -> returns size */
+	error = fwnode_property_read_string_array(node, "strs", NULL, 0);
+	KUNIT_EXPECT_EQ(test, error, 2);
+
+	/* accessing array as single value */
+	error = fwnode_property_read_string(node, "strs", &str);
+	KUNIT_EXPECT_EQ(test, error, 0);
+	KUNIT_EXPECT_STREQ(test, str, "string-a");
+
+	fwnode_remove_software_node(node);
+}
+
+static void pe_test_bool(struct kunit *test)
+{
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_BOOL("prop"),
+		{ }
+	};
+
+	struct fwnode_handle *node;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	KUNIT_EXPECT_TRUE(test, fwnode_property_read_bool(node, "prop"));
+	KUNIT_EXPECT_FALSE(test, fwnode_property_read_bool(node, "not-prop"));
+
+	fwnode_remove_software_node(node);
+}
+
+/* Verifies that small U8 array is stored inline when property is copied */
+static void pe_test_move_inline_u8(struct kunit *test)
+{
+	static const u8 u8_array_small[8] = { 1, 2, 3, 4 };
+	static const u8 u8_array_big[128] = { 5, 6, 7, 8 };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U8_ARRAY("small", u8_array_small),
+		PROPERTY_ENTRY_U8_ARRAY("big", u8_array_big),
+		{ }
+	};
+
+	struct property_entry *copy;
+	const u8 *data_ptr;
+
+	copy = property_entries_dup(entries);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, copy);
+
+	KUNIT_EXPECT_TRUE(test, copy[0].is_inline);
+	data_ptr = (u8 *)&copy[0].value;
+	KUNIT_EXPECT_EQ(test, data_ptr[0], 1);
+	KUNIT_EXPECT_EQ(test, data_ptr[1], 2);
+
+	KUNIT_EXPECT_FALSE(test, copy[1].is_inline);
+	data_ptr = copy[1].pointer;
+	KUNIT_EXPECT_EQ(test, data_ptr[0], 5);
+	KUNIT_EXPECT_EQ(test, data_ptr[1], 6);
+
+	property_entries_free(copy);
+}
+
+/* Verifies that single string array is stored inline when property is copied */
+static void pe_test_move_inline_str(struct kunit *test)
+{
+	static char *str_array_small[] = { "a" };
+	static char *str_array_big[] = { "b", "c", "d", "e" };
+	static char *str_array_small_empty[] = { "" };
+	static struct property_entry entries[] = {
+		PROPERTY_ENTRY_STRING_ARRAY("small", str_array_small),
+		PROPERTY_ENTRY_STRING_ARRAY("big", str_array_big),
+		PROPERTY_ENTRY_STRING_ARRAY("small-empty", str_array_small_empty),
+		{ }
+	};
+
+	struct property_entry *copy;
+	const char * const *data_ptr;
+
+	copy = property_entries_dup(entries);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, copy);
+
+	KUNIT_EXPECT_TRUE(test, copy[0].is_inline);
+	KUNIT_EXPECT_STREQ(test, copy[0].value.str[0], "a");
+
+	KUNIT_EXPECT_FALSE(test, copy[1].is_inline);
+	data_ptr = copy[1].pointer;
+	KUNIT_EXPECT_STREQ(test, data_ptr[0], "b");
+	KUNIT_EXPECT_STREQ(test, data_ptr[1], "c");
+
+	KUNIT_EXPECT_TRUE(test, copy[2].is_inline);
+	KUNIT_EXPECT_STREQ(test, copy[2].value.str[0], "");
+
+	property_entries_free(copy);
+}
+
+/* Handling of reference properties */
+static void pe_test_reference(struct kunit *test)
+{
+	static const struct software_node node1 = { .name = "1" };
+	static const struct software_node node2 = { .name = "2" };
+	static const struct software_node *group[] = { &node1, &node2, NULL };
+
+	static const struct software_node_ref_args refs[] = {
+		SOFTWARE_NODE_REFERENCE(&node1),
+		SOFTWARE_NODE_REFERENCE(&node2, 3, 4),
+	};
+
+	const struct property_entry entries[] = {
+		PROPERTY_ENTRY_REF("ref-1", &node1),
+		PROPERTY_ENTRY_REF("ref-2", &node2, 1, 2),
+		PROPERTY_ENTRY_REF_ARRAY("ref-3", refs),
+		{ }
+	};
+
+	struct fwnode_handle *node;
+	struct fwnode_reference_args ref;
+	int error;
+
+	error = software_node_register_node_group(group);
+	KUNIT_ASSERT_EQ(test, error, 0);
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	error = fwnode_property_get_reference_args(node, "ref-1", NULL,
+						   0, 0, &ref);
+	KUNIT_ASSERT_EQ(test, error, 0);
+	KUNIT_EXPECT_PTR_EQ(test, to_software_node(ref.fwnode), &node1);
+	KUNIT_EXPECT_EQ(test, ref.nargs, 0U);
+
+	/* wrong index */
+	error = fwnode_property_get_reference_args(node, "ref-1", NULL,
+						   0, 1, &ref);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	error = fwnode_property_get_reference_args(node, "ref-2", NULL,
+						   1, 0, &ref);
+	KUNIT_ASSERT_EQ(test, error, 0);
+	KUNIT_EXPECT_PTR_EQ(test, to_software_node(ref.fwnode), &node2);
+	KUNIT_EXPECT_EQ(test, ref.nargs, 1U);
+	KUNIT_EXPECT_EQ(test, ref.args[0], 1LLU);
+
+	/* asking for more args, padded with zero data */
+	error = fwnode_property_get_reference_args(node, "ref-2", NULL,
+						   3, 0, &ref);
+	KUNIT_ASSERT_EQ(test, error, 0);
+	KUNIT_EXPECT_PTR_EQ(test, to_software_node(ref.fwnode), &node2);
+	KUNIT_EXPECT_EQ(test, ref.nargs, 3U);
+	KUNIT_EXPECT_EQ(test, ref.args[0], 1LLU);
+	KUNIT_EXPECT_EQ(test, ref.args[1], 2LLU);
+	KUNIT_EXPECT_EQ(test, ref.args[2], 0LLU);
+
+	/* wrong index */
+	error = fwnode_property_get_reference_args(node, "ref-2", NULL,
+						   2, 1, &ref);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	/* array of references */
+	error = fwnode_property_get_reference_args(node, "ref-3", NULL,
+						   0, 0, &ref);
+	KUNIT_ASSERT_EQ(test, error, 0);
+	KUNIT_EXPECT_PTR_EQ(test, to_software_node(ref.fwnode), &node1);
+	KUNIT_EXPECT_EQ(test, ref.nargs, 0U);
+
+	/* second reference in the array */
+	error = fwnode_property_get_reference_args(node, "ref-3", NULL,
+						   2, 1, &ref);
+	KUNIT_ASSERT_EQ(test, error, 0);
+	KUNIT_EXPECT_PTR_EQ(test, to_software_node(ref.fwnode), &node2);
+	KUNIT_EXPECT_EQ(test, ref.nargs, 2U);
+	KUNIT_EXPECT_EQ(test, ref.args[0], 3LLU);
+	KUNIT_EXPECT_EQ(test, ref.args[1], 4LLU);
+
+	/* wrong index */
+	error = fwnode_property_get_reference_args(node, "ref-1", NULL,
+						   0, 2, &ref);
+	KUNIT_EXPECT_NE(test, error, 0);
+
+	fwnode_remove_software_node(node);
+	software_node_unregister_node_group(group);
+}
+
+static struct fwnode_handle *create_device_node(struct kunit *test,
+						const char *name,
+						const char *full_name,
+						struct device_node *parent)
+{
+	struct device_node *node;
+
+	node = kunit_kzalloc(test, sizeof(*node), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	node->name = kunit_kstrdup(test, name, GFP_KERNEL);
+	node->full_name = kunit_kstrdup(test, full_name, GFP_KERNEL);
+
+	if (parent) {
+		node->sibling = parent->child;
+		/* set the node as the first child of the parent */
+		parent->child = node;
+		node->parent = parent;
+	}
+
+	of_node_init(node);
+	return of_fwnode_handle(node);
+}
+
+/* Verifies that fwnode_for_each_child_node() can output correct children */
+static void pe_test_child_iteration(struct kunit *test)
+{
+	struct fwnode_handle *of_node, *of_node1;
+	struct fwnode_handle *sw_node, *sw_node1;
+	struct fwnode_handle *child;
+	int error, i, num;
+
+	if (!IS_ENABLED(CONFIG_OF))
+		kunit_skip(test, "requires CONFIG_OF");
+
+	static const struct software_node node = { .name = "sw" };
+	static const struct software_node node1 = { .name = "sw-1", .parent = &node};
+	static const struct software_node node2 = { .name = "sw-2", .parent = &node};
+	static const struct software_node node3 = { .name = "sw-3", .parent = &node};
+	static const struct software_node *group[] = { &node, &node1, &node2, &node3, NULL };
+
+	static const char * const of_child_array[] = { "of-1", "of-2", "of-3" };
+	static const char * const sw_child_array[] = { "sw-1", "sw-2", "sw-3" };
+	static const char * const of_sw_child_array[] = { "of-1", "of-2", "of-3",
+							  "sw-1", "sw-2", "sw-3" };
+	static const char * const sw_of_child_array[] = { "sw-1", "sw-2", "sw-3",
+							  "of-1", "of-2", "of-3" };
+
+	/* 1. Test OF node child iteration */
+
+	of_node = create_device_node(test, "of", "of", NULL);
+	create_device_node(test, "of", "of-3", to_of_node(of_node));
+	create_device_node(test, "of", "of-2", to_of_node(of_node));
+	of_node1 = create_device_node(test, "of", "of-1", to_of_node(of_node));
+
+	i = 0;
+	num = ARRAY_SIZE(of_child_array);
+	fwnode_for_each_child_node(of_node, child) {
+		KUNIT_ASSERT_LT(test, i, num);
+		KUNIT_EXPECT_STREQ(test, of_child_array[i++], fwnode_get_name(child));
+	}
+	KUNIT_EXPECT_PTR_EQ(test, child, NULL);
+
+	/* 2. Test SW node child iteration */
+
+	error = software_node_register_node_group(group);
+	KUNIT_ASSERT_EQ(test, error, 0);
+
+	sw_node = software_node_fwnode(&node);
+
+	i = 0;
+	num = ARRAY_SIZE(sw_child_array);
+	fwnode_for_each_child_node(sw_node, child) {
+		KUNIT_ASSERT_LT(test, i, num);
+		KUNIT_EXPECT_STREQ(test, sw_child_array[i++], fwnode_get_name(child));
+	}
+	KUNIT_EXPECT_PTR_EQ(test, child, NULL);
+
+	/* 3. Test OF (primary) + SW (secondary) node child iteration */
+
+	of_node->secondary = sw_node;
+	sw_node->secondary = ERR_PTR(-ENODEV);
+
+	i = 0;
+	num = ARRAY_SIZE(of_sw_child_array);
+	fwnode_for_each_child_node(of_node, child) {
+		KUNIT_ASSERT_LT(test, i, num);
+		KUNIT_EXPECT_STREQ(test, of_sw_child_array[i++], fwnode_get_name(child));
+	}
+	KUNIT_EXPECT_PTR_EQ(test, child, NULL);
+
+	/* 4. Test SW (primary) + OF (secondary) node child iteration */
+
+	sw_node->secondary = of_node;
+	of_node->secondary = ERR_PTR(-ENODEV);
+
+	i = 0;
+	num = ARRAY_SIZE(sw_of_child_array);
+	fwnode_for_each_child_node(sw_node, child) {
+		KUNIT_ASSERT_LT(test, i, num);
+		KUNIT_EXPECT_STREQ(test, sw_of_child_array[i++], fwnode_get_name(child));
+	}
+	KUNIT_EXPECT_PTR_EQ(test, child, NULL);
+
+	/* 5. Test OF (primary) + SW (secondary, but no children) node child iteration */
+
+	sw_node1 = software_node_fwnode(&node1);
+	of_node->secondary = sw_node1;
+	sw_node->secondary = ERR_PTR(-ENODEV);
+
+	i = 0;
+	num = ARRAY_SIZE(of_child_array);
+	fwnode_for_each_child_node(of_node, child) {
+		KUNIT_ASSERT_LT(test, i, num);
+		KUNIT_EXPECT_STREQ(test, of_child_array[i++], fwnode_get_name(child));
+	}
+	KUNIT_EXPECT_PTR_EQ(test, child, NULL);
+
+	/* 6. Test SW (primary) + OF (secondary, but no children) node child iteration */
+
+	sw_node->secondary = of_node1;
+	of_node->secondary = ERR_PTR(-ENODEV);
+
+	i = 0;
+	num = ARRAY_SIZE(sw_child_array);
+	fwnode_for_each_child_node(sw_node, child) {
+		KUNIT_ASSERT_LT(test, i, num);
+		KUNIT_EXPECT_STREQ(test, sw_child_array[i++], fwnode_get_name(child));
+	}
+	KUNIT_EXPECT_PTR_EQ(test, child, NULL);
+
+	of_node->secondary = NULL;
+	sw_node->secondary = NULL;
+	software_node_unregister_node_group(group);
+}
+
+static struct kunit_case property_entry_test_cases[] = {
+	KUNIT_CASE(pe_test_uints),
+	KUNIT_CASE(pe_test_uint_arrays),
+	KUNIT_CASE(pe_test_strings),
+	KUNIT_CASE(pe_test_bool),
+	KUNIT_CASE(pe_test_move_inline_u8),
+	KUNIT_CASE(pe_test_move_inline_str),
+	KUNIT_CASE(pe_test_reference),
+	KUNIT_CASE(pe_test_child_iteration),
+	{ }
+};
+
+static struct kunit_suite property_entry_test_suite = {
+	.name = "property-entry",
+	.test_cases = property_entry_test_cases,
+};
+
+kunit_test_suite(property_entry_test_suite);
+
+MODULE_DESCRIPTION("Test module for the property entry API");
+MODULE_AUTHOR("Dmitry Torokhov <dtor@chromium.org>");
+MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING");
+MODULE_LICENSE("GPL");