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, 111 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-ge.c b/drivers/gpio/gpio-ge.c
new file mode 100644
index 000000000..d0c8e16f1
--- /dev/null
+++ b/drivers/gpio/gpio-ge.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for GE FPGA based GPIO
+ *
+ * Author: Martyn Welch <martyn.welch@ge.com>
+ *
+ * 2008 (c) GE Intelligent Platforms Embedded Systems, Inc.
+ */
+
+/*
+ * TODO:
+ *
+ * Configuration of output modes (totem-pole/open-drain).
+ * Interrupt configuration - interrupts are always generated, the FPGA relies
+ * on the I/O interrupt controllers mask to stop them from being propagated.
+ */
+
+#include <linux/gpio/driver.h>
+#include <linux/gpio/generic.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+
+#define GEF_GPIO_DIRECT		0x00
+#define GEF_GPIO_IN		0x04
+#define GEF_GPIO_OUT		0x08
+#define GEF_GPIO_TRIG		0x0C
+#define GEF_GPIO_POLAR_A	0x10
+#define GEF_GPIO_POLAR_B	0x14
+#define GEF_GPIO_INT_STAT	0x18
+#define GEF_GPIO_OVERRUN	0x1C
+#define GEF_GPIO_MODE		0x20
+
+static const struct of_device_id gef_gpio_ids[] = {
+	{
+		.compatible	= "gef,sbc610-gpio",
+		.data		= (void *)19,
+	}, {
+		.compatible	= "gef,sbc310-gpio",
+		.data		= (void *)6,
+	}, {
+		.compatible	= "ge,imp3a-gpio",
+		.data		= (void *)16,
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, gef_gpio_ids);
+
+static int __init gef_gpio_probe(struct platform_device *pdev)
+{
+	struct gpio_generic_chip_config config;
+	struct device *dev = &pdev->dev;
+	struct gpio_generic_chip *chip;
+	struct gpio_chip *gc;
+	void __iomem *regs;
+	int ret;
+
+	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(regs))
+		return PTR_ERR(regs);
+
+	config = (struct gpio_generic_chip_config) {
+		.dev = dev,
+		.sz = 4,
+		.dat = regs + GEF_GPIO_IN,
+		.set = regs + GEF_GPIO_OUT,
+		.dirin = regs + GEF_GPIO_DIRECT,
+		.flags = GPIO_GENERIC_BIG_ENDIAN_BYTE_ORDER,
+	};
+
+	ret = gpio_generic_chip_init(chip, &config);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "failed to initialize the generic GPIO chip\n");
+
+	gc = &chip->gc;
+
+	/* Setup pointers to chip functions */
+	gc->label = devm_kasprintf(dev, GFP_KERNEL, "%pfw", dev_fwnode(dev));
+	if (!gc->label)
+		return -ENOMEM;
+
+	gc->base = -1;
+	gc->ngpio = (uintptr_t)device_get_match_data(dev);
+
+	/* This function adds a memory mapped GPIO chip */
+	ret = devm_gpiochip_add_data(dev, gc, NULL);
+	if (ret)
+		return dev_err_probe(dev, ret, "GPIO chip registration failed\n");
+
+	return 0;
+};
+
+static struct platform_driver gef_gpio_driver = {
+	.driver = {
+		.name		= "gef-gpio",
+		.of_match_table	= gef_gpio_ids,
+	},
+};
+module_platform_driver_probe(gef_gpio_driver, gef_gpio_probe);
+
+MODULE_DESCRIPTION("GE I/O FPGA GPIO driver");
+MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
+MODULE_LICENSE("GPL");