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, 60 insertions, 0 deletions

diff --git a/drivers/pinctrl/pinctrl-mcp23s08.h b/drivers/pinctrl/pinctrl-mcp23s08.h
new file mode 100644
index 000000000..105bce9e0
--- /dev/null
+++ b/drivers/pinctrl/pinctrl-mcp23s08.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* MCP23S08 SPI/I2C GPIO driver */
+
+#include <linux/gpio/driver.h>
+#include <linux/irq.h>
+#include <linux/mutex.h>
+#include <linux/pinctrl/pinctrl.h>
+#include <linux/types.h>
+
+/*
+ * MCP types supported by driver
+ */
+#define MCP_TYPE_S08	1
+#define MCP_TYPE_S17	2
+#define MCP_TYPE_008	3
+#define MCP_TYPE_017	4
+#define MCP_TYPE_S18	5
+#define MCP_TYPE_018	6
+
+struct device;
+struct regmap;
+
+struct pinctrl_dev;
+
+struct mcp23s08_info {
+	const struct regmap_config *regmap;
+	const char *label;
+	unsigned int type;
+	u16 ngpio;
+	bool reg_shift;
+};
+
+struct mcp23s08 {
+	u8			addr;
+	bool			irq_active_high;
+	bool			reg_shift;
+
+	u16			irq_rise;
+	u16			irq_fall;
+	int			irq;
+	bool			irq_controller;
+	int			cached_gpio;
+	/* lock protects regmap access with bypass/cache flags */
+	struct mutex		lock;
+
+	struct gpio_chip	chip;
+
+	struct regmap		*regmap;
+	struct device		*dev;
+
+	struct pinctrl_dev	*pctldev;
+	struct pinctrl_desc	pinctrl_desc;
+	struct gpio_desc        *reset_gpio;
+};
+
+extern const struct regmap_config mcp23x08_regmap;
+extern const struct regmap_config mcp23x17_regmap;
+
+int mcp23s08_probe_one(struct mcp23s08 *mcp, struct device *dev,
+		       unsigned int addr, unsigned int type, unsigned int base);