selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 78 insertions, 0 deletions

diff --git a/drivers/nvmem/apple-spmi-nvmem.c b/drivers/nvmem/apple-spmi-nvmem.c
new file mode 100644
index 000000000..7acb0c07d
--- /dev/null
+++ b/drivers/nvmem/apple-spmi-nvmem.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple SPMI NVMEM driver
+ *
+ * Copyright The Asahi Linux Contributors
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/spmi.h>
+#include <linux/regmap.h>
+
+static const struct regmap_config apple_spmi_regmap_config = {
+	.reg_bits	= 16,
+	.val_bits	= 8,
+	.max_register	= 0xffff,
+};
+
+static int apple_spmi_nvmem_read(void *priv, unsigned int offset, void *val,
+				 size_t bytes)
+{
+	struct regmap *map = priv;
+
+	return regmap_bulk_read(map, offset, val, bytes);
+}
+
+static int apple_spmi_nvmem_write(void *priv, unsigned int offset, void *val,
+				  size_t bytes)
+{
+	struct regmap *map = priv;
+
+	return regmap_bulk_write(map, offset, val, bytes);
+}
+
+static int apple_spmi_nvmem_probe(struct spmi_device *sdev)
+{
+	struct regmap *regmap;
+	struct nvmem_config nvmem_cfg = {
+		.dev = &sdev->dev,
+		.name = "spmi_nvmem",
+		.id = NVMEM_DEVID_AUTO,
+		.word_size = 1,
+		.stride = 1,
+		.size = 0xffff,
+		.reg_read = apple_spmi_nvmem_read,
+		.reg_write = apple_spmi_nvmem_write,
+	};
+
+	regmap = devm_regmap_init_spmi_ext(sdev, &apple_spmi_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	nvmem_cfg.priv = regmap;
+
+	return PTR_ERR_OR_ZERO(devm_nvmem_register(&sdev->dev, &nvmem_cfg));
+}
+
+static const struct of_device_id apple_spmi_nvmem_id_table[] = {
+	{ .compatible = "apple,spmi-nvmem" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, apple_spmi_nvmem_id_table);
+
+static struct spmi_driver apple_spmi_nvmem_driver = {
+	.probe = apple_spmi_nvmem_probe,
+	.driver = {
+		.name = "apple-spmi-nvmem",
+		.of_match_table	= apple_spmi_nvmem_id_table,
+	},
+};
+
+module_spmi_driver(apple_spmi_nvmem_driver);
+
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
+MODULE_DESCRIPTION("Apple SPMI NVMEM driver");