selftests/bpf: Test rhtab kptr cancellation semanticsgrafted

Resizable hash-map updates and deletions must not perform full special-field
destruction in their caller context. In particular, a referenced kptr must
remain attached to the allocation until the memory allocator destructor can
release it safely.

Add separate coverage for both affected paths. The update test stores a task
kptr, replaces the ordinary value bytes with BPF_EXIST, and verifies that the
kptr survived. The delete test removes an element and exchanges its kptr
through the still-valid map-value pointer before the allocation is reclaimed.

Both cases observe a NULL kptr when rhtab uses bpf_obj_free_fields(). They
recover and release the reference after rhtab switches to cancellation
semantics.

Signed-off-by: Nuoqi Gui <gnq25@mails.tsinghua.edu.cn>
[ kkd: Split update and delete coverage and rewrote the commit log ]
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904104203.345917-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 73 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-ps3.c b/drivers/rtc/rtc-ps3.c
new file mode 100644
index 000000000..6b098734c
--- /dev/null
+++ b/drivers/rtc/rtc-ps3.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PS3 RTC Driver
+ *
+ * Copyright 2009 Sony Corporation
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+#include <asm/lv1call.h>
+#include <asm/ps3.h>
+
+
+static u64 read_rtc(void)
+{
+	int result;
+	u64 rtc_val;
+	u64 tb_val;
+
+	result = lv1_get_rtc(&rtc_val, &tb_val);
+	BUG_ON(result);
+
+	return rtc_val;
+}
+
+static int ps3_get_time(struct device *dev, struct rtc_time *tm)
+{
+	rtc_time64_to_tm(read_rtc() + ps3_os_area_get_rtc_diff(), tm);
+	return 0;
+}
+
+static int ps3_set_time(struct device *dev, struct rtc_time *tm)
+{
+	ps3_os_area_set_rtc_diff(rtc_tm_to_time64(tm) - read_rtc());
+	return 0;
+}
+
+static const struct rtc_class_ops ps3_rtc_ops = {
+	.read_time = ps3_get_time,
+	.set_time = ps3_set_time,
+};
+
+static int __init ps3_rtc_probe(struct platform_device *dev)
+{
+	struct rtc_device *rtc;
+
+	rtc = devm_rtc_allocate_device(&dev->dev);
+	if (IS_ERR(rtc))
+		return PTR_ERR(rtc);
+
+	rtc->ops = &ps3_rtc_ops;
+	rtc->range_max = U64_MAX;
+
+	platform_set_drvdata(dev, rtc);
+
+	return devm_rtc_register_device(rtc);
+}
+
+static struct platform_driver ps3_rtc_driver = {
+	.driver = {
+		.name = "rtc-ps3",
+	},
+};
+
+module_platform_driver_probe(ps3_rtc_driver, ps3_rtc_probe);
+
+MODULE_AUTHOR("Sony Corporation");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ps3 RTC driver");
+MODULE_ALIAS("platform:rtc-ps3");