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, 211 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-xgene.c b/drivers/gpio/gpio-xgene.c
new file mode 100644
index 000000000..809668449
--- /dev/null
+++ b/drivers/gpio/gpio-xgene.c
@@ -0,0 +1,211 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AppliedMicro X-Gene SoC GPIO Driver
+ *
+ * Copyright (c) 2014, Applied Micro Circuits Corporation
+ * Author: Feng Kan <fkan@apm.com>.
+ */
+
+#include <linux/acpi.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/spinlock.h>
+#include <linux/platform_device.h>
+#include <linux/gpio/driver.h>
+#include <linux/types.h>
+#include <linux/bitops.h>
+
+#define GPIO_SET_DR_OFFSET	0x0C
+#define GPIO_DATA_OFFSET	0x14
+#define GPIO_BANK_STRIDE	0x0C
+
+#define XGENE_GPIOS_PER_BANK	16
+#define XGENE_MAX_GPIO_BANKS	3
+#define XGENE_MAX_GPIOS		(XGENE_GPIOS_PER_BANK * XGENE_MAX_GPIO_BANKS)
+
+#define GPIO_BIT_OFFSET(x)	(x % XGENE_GPIOS_PER_BANK)
+#define GPIO_BANK_OFFSET(x)	((x / XGENE_GPIOS_PER_BANK) * GPIO_BANK_STRIDE)
+
+struct xgene_gpio {
+	struct gpio_chip	chip;
+	void __iomem		*base;
+	spinlock_t		lock;
+	u32			set_dr_val[XGENE_MAX_GPIO_BANKS];
+};
+
+static int xgene_gpio_get(struct gpio_chip *gc, unsigned int offset)
+{
+	struct xgene_gpio *chip = gpiochip_get_data(gc);
+	unsigned long bank_offset;
+	u32 bit_offset;
+
+	bank_offset = GPIO_DATA_OFFSET + GPIO_BANK_OFFSET(offset);
+	bit_offset = GPIO_BIT_OFFSET(offset);
+	return !!(ioread32(chip->base + bank_offset) & BIT(bit_offset));
+}
+
+static void __xgene_gpio_set(struct gpio_chip *gc, unsigned int offset, int val)
+{
+	struct xgene_gpio *chip = gpiochip_get_data(gc);
+	unsigned long bank_offset;
+	u32 setval, bit_offset;
+
+	bank_offset = GPIO_SET_DR_OFFSET + GPIO_BANK_OFFSET(offset);
+	bit_offset = GPIO_BIT_OFFSET(offset) + XGENE_GPIOS_PER_BANK;
+
+	setval = ioread32(chip->base + bank_offset);
+	if (val)
+		setval |= BIT(bit_offset);
+	else
+		setval &= ~BIT(bit_offset);
+	iowrite32(setval, chip->base + bank_offset);
+}
+
+static int xgene_gpio_set(struct gpio_chip *gc, unsigned int offset, int val)
+{
+	struct xgene_gpio *chip = gpiochip_get_data(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&chip->lock, flags);
+	__xgene_gpio_set(gc, offset, val);
+	spin_unlock_irqrestore(&chip->lock, flags);
+
+	return 0;
+}
+
+static int xgene_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	struct xgene_gpio *chip = gpiochip_get_data(gc);
+	unsigned long bank_offset, bit_offset;
+
+	bank_offset = GPIO_SET_DR_OFFSET + GPIO_BANK_OFFSET(offset);
+	bit_offset = GPIO_BIT_OFFSET(offset);
+
+	if (ioread32(chip->base + bank_offset) & BIT(bit_offset))
+		return GPIO_LINE_DIRECTION_IN;
+
+	return GPIO_LINE_DIRECTION_OUT;
+}
+
+static int xgene_gpio_dir_in(struct gpio_chip *gc, unsigned int offset)
+{
+	struct xgene_gpio *chip = gpiochip_get_data(gc);
+	unsigned long flags, bank_offset;
+	u32 dirval, bit_offset;
+
+	bank_offset = GPIO_SET_DR_OFFSET + GPIO_BANK_OFFSET(offset);
+	bit_offset = GPIO_BIT_OFFSET(offset);
+
+	spin_lock_irqsave(&chip->lock, flags);
+
+	dirval = ioread32(chip->base + bank_offset);
+	dirval |= BIT(bit_offset);
+	iowrite32(dirval, chip->base + bank_offset);
+
+	spin_unlock_irqrestore(&chip->lock, flags);
+
+	return 0;
+}
+
+static int xgene_gpio_dir_out(struct gpio_chip *gc,
+					unsigned int offset, int val)
+{
+	struct xgene_gpio *chip = gpiochip_get_data(gc);
+	unsigned long flags, bank_offset;
+	u32 dirval, bit_offset;
+
+	bank_offset = GPIO_SET_DR_OFFSET + GPIO_BANK_OFFSET(offset);
+	bit_offset = GPIO_BIT_OFFSET(offset);
+
+	spin_lock_irqsave(&chip->lock, flags);
+
+	dirval = ioread32(chip->base + bank_offset);
+	dirval &= ~BIT(bit_offset);
+	iowrite32(dirval, chip->base + bank_offset);
+	__xgene_gpio_set(gc, offset, val);
+
+	spin_unlock_irqrestore(&chip->lock, flags);
+
+	return 0;
+}
+
+static int xgene_gpio_suspend(struct device *dev)
+{
+	struct xgene_gpio *gpio = dev_get_drvdata(dev);
+	unsigned long bank_offset;
+	unsigned int bank;
+
+	for (bank = 0; bank < XGENE_MAX_GPIO_BANKS; bank++) {
+		bank_offset = GPIO_SET_DR_OFFSET + bank * GPIO_BANK_STRIDE;
+		gpio->set_dr_val[bank] = ioread32(gpio->base + bank_offset);
+	}
+	return 0;
+}
+
+static int xgene_gpio_resume(struct device *dev)
+{
+	struct xgene_gpio *gpio = dev_get_drvdata(dev);
+	unsigned long bank_offset;
+	unsigned int bank;
+
+	for (bank = 0; bank < XGENE_MAX_GPIO_BANKS; bank++) {
+		bank_offset = GPIO_SET_DR_OFFSET + bank * GPIO_BANK_STRIDE;
+		iowrite32(gpio->set_dr_val[bank], gpio->base + bank_offset);
+	}
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(xgene_gpio_pm, xgene_gpio_suspend, xgene_gpio_resume);
+
+static int xgene_gpio_probe(struct platform_device *pdev)
+{
+	struct xgene_gpio *gpio;
+
+	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
+	if (!gpio)
+		return -ENOMEM;
+
+	gpio->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(gpio->base))
+		return PTR_ERR(gpio->base);
+
+	gpio->chip.ngpio = XGENE_MAX_GPIOS;
+
+	spin_lock_init(&gpio->lock);
+	gpio->chip.parent = &pdev->dev;
+	gpio->chip.get_direction = xgene_gpio_get_direction;
+	gpio->chip.direction_input = xgene_gpio_dir_in;
+	gpio->chip.direction_output = xgene_gpio_dir_out;
+	gpio->chip.get = xgene_gpio_get;
+	gpio->chip.set = xgene_gpio_set;
+	gpio->chip.label = dev_name(&pdev->dev);
+	gpio->chip.base = -1;
+
+	platform_set_drvdata(pdev, gpio);
+
+	return devm_gpiochip_add_data(&pdev->dev, &gpio->chip, gpio);
+}
+
+static const struct of_device_id xgene_gpio_of_match[] = {
+	{ .compatible = "apm,xgene-gpio", },
+	{},
+};
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id xgene_gpio_acpi_match[] = {
+	{ "APMC0D14", 0 },
+	{ },
+};
+#endif
+
+static struct platform_driver xgene_gpio_driver = {
+	.driver = {
+		.name = "xgene-gpio",
+		.of_match_table = xgene_gpio_of_match,
+		.acpi_match_table = ACPI_PTR(xgene_gpio_acpi_match),
+		.pm     = pm_sleep_ptr(&xgene_gpio_pm),
+	},
+	.probe = xgene_gpio_probe,
+};
+builtin_platform_driver(xgene_gpio_driver);