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, 61 insertions, 0 deletions

diff --git a/drivers/pinctrl/mediatek/pinctrl-rt2880.c b/drivers/pinctrl/mediatek/pinctrl-rt2880.c
new file mode 100644
index 000000000..e0366721a
--- /dev/null
+++ b/drivers/pinctrl/mediatek/pinctrl-rt2880.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/bitops.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include "pinctrl-mtmips.h"
+
+#define RT2880_GPIO_MODE_I2C		BIT(0)
+#define RT2880_GPIO_MODE_UART0		BIT(1)
+#define RT2880_GPIO_MODE_SPI		BIT(2)
+#define RT2880_GPIO_MODE_UART1		BIT(3)
+#define RT2880_GPIO_MODE_JTAG		BIT(4)
+#define RT2880_GPIO_MODE_MDIO		BIT(5)
+#define RT2880_GPIO_MODE_SDRAM		BIT(6)
+#define RT2880_GPIO_MODE_PCI		BIT(7)
+
+static struct mtmips_pmx_func i2c_grp[] = { FUNC("i2c", 0, 1, 2) };
+static struct mtmips_pmx_func spi_grp[] = { FUNC("spi", 0, 3, 4) };
+static struct mtmips_pmx_func uartlite_grp[] = { FUNC("uartlite", 0, 7, 8) };
+static struct mtmips_pmx_func jtag_grp[] = { FUNC("jtag", 0, 17, 5) };
+static struct mtmips_pmx_func mdio_grp[] = { FUNC("mdio", 0, 22, 2) };
+static struct mtmips_pmx_func sdram_grp[] = { FUNC("sdram", 0, 24, 16) };
+static struct mtmips_pmx_func pci_grp[] = { FUNC("pci", 0, 40, 32) };
+
+static struct mtmips_pmx_group rt2880_pinmux_data_act[] = {
+	GRP("i2c", i2c_grp, 1, RT2880_GPIO_MODE_I2C),
+	GRP("spi", spi_grp, 1, RT2880_GPIO_MODE_SPI),
+	GRP("uartlite", uartlite_grp, 1, RT2880_GPIO_MODE_UART0),
+	GRP("jtag", jtag_grp, 1, RT2880_GPIO_MODE_JTAG),
+	GRP("mdio", mdio_grp, 1, RT2880_GPIO_MODE_MDIO),
+	GRP("sdram", sdram_grp, 1, RT2880_GPIO_MODE_SDRAM),
+	GRP("pci", pci_grp, 1, RT2880_GPIO_MODE_PCI),
+	{ 0 }
+};
+
+static int rt2880_pinctrl_probe(struct platform_device *pdev)
+{
+	return mtmips_pinctrl_init(pdev, rt2880_pinmux_data_act);
+}
+
+static const struct of_device_id rt2880_pinctrl_match[] = {
+	{ .compatible = "ralink,rt2880-pinctrl" },
+	{ .compatible = "ralink,rt2880-pinmux" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rt2880_pinctrl_match);
+
+static struct platform_driver rt2880_pinctrl_driver = {
+	.probe = rt2880_pinctrl_probe,
+	.driver = {
+		.name = "rt2880-pinctrl",
+		.of_match_table = rt2880_pinctrl_match,
+	},
+};
+
+static int __init rt2880_pinctrl_init(void)
+{
+	return platform_driver_register(&rt2880_pinctrl_driver);
+}
+core_initcall_sync(rt2880_pinctrl_init);