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, 143 insertions, 0 deletions

diff --git a/drivers/nvmem/imx-iim.c b/drivers/nvmem/imx-iim.c
new file mode 100644
index 000000000..8cfbe55a5
--- /dev/null
+++ b/drivers/nvmem/imx-iim.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * i.MX IIM driver
+ *
+ * Copyright (c) 2017 Pengutronix, Michael Grzeschik <m.grzeschik@pengutronix.de>
+ *
+ * Based on the barebox iim driver,
+ * Copyright (c) 2010 Baruch Siach <baruch@tkos.co.il>,
+ *	Orex Computed Radiography
+ */
+
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+
+#define IIM_BANK_BASE(n)	(0x800 + 0x400 * (n))
+
+struct imx_iim_drvdata {
+	unsigned int nregs;
+};
+
+struct iim_priv {
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static int imx_iim_read(void *context, unsigned int offset,
+			  void *buf, size_t bytes)
+{
+	struct iim_priv *iim = context;
+	int i, ret;
+	u8 *buf8 = buf;
+
+	ret = clk_prepare_enable(iim->clk);
+	if (ret)
+		return ret;
+
+	for (i = offset; i < offset + bytes; i++) {
+		int bank = i >> 5;
+		int reg = i & 0x1f;
+
+		*buf8++ = readl(iim->base + IIM_BANK_BASE(bank) + reg * 4);
+	}
+
+	clk_disable_unprepare(iim->clk);
+
+	return 0;
+}
+
+static struct imx_iim_drvdata imx27_drvdata = {
+	.nregs = 2 * 32,
+};
+
+static struct imx_iim_drvdata imx25_imx31_imx35_drvdata = {
+	.nregs = 3 * 32,
+};
+
+static struct imx_iim_drvdata imx51_drvdata = {
+	.nregs = 4 * 32,
+};
+
+static struct imx_iim_drvdata imx53_drvdata = {
+	.nregs = 4 * 32 + 16,
+};
+
+static const struct of_device_id imx_iim_dt_ids[] = {
+	{
+		.compatible = "fsl,imx25-iim",
+		.data = &imx25_imx31_imx35_drvdata,
+	}, {
+		.compatible = "fsl,imx27-iim",
+		.data = &imx27_drvdata,
+	}, {
+		.compatible = "fsl,imx31-iim",
+		.data = &imx25_imx31_imx35_drvdata,
+	}, {
+		.compatible = "fsl,imx35-iim",
+		.data = &imx25_imx31_imx35_drvdata,
+	}, {
+		.compatible = "fsl,imx51-iim",
+		.data = &imx51_drvdata,
+	}, {
+		.compatible = "fsl,imx53-iim",
+		.data = &imx53_drvdata,
+	}, {
+		/* sentinel */
+	},
+};
+MODULE_DEVICE_TABLE(of, imx_iim_dt_ids);
+
+static int imx_iim_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct iim_priv *iim;
+	struct nvmem_device *nvmem;
+	struct nvmem_config cfg = {};
+	const struct imx_iim_drvdata *drvdata = NULL;
+
+	iim = devm_kzalloc(dev, sizeof(*iim), GFP_KERNEL);
+	if (!iim)
+		return -ENOMEM;
+
+	iim->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(iim->base))
+		return PTR_ERR(iim->base);
+
+	drvdata = of_device_get_match_data(&pdev->dev);
+
+	iim->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(iim->clk))
+		return PTR_ERR(iim->clk);
+
+	cfg.name = "imx-iim";
+	cfg.read_only = true;
+	cfg.word_size = 1;
+	cfg.stride = 1;
+	cfg.reg_read = imx_iim_read;
+	cfg.dev = dev;
+	cfg.size = drvdata->nregs;
+	cfg.priv = iim;
+
+	nvmem = devm_nvmem_register(dev, &cfg);
+
+	return PTR_ERR_OR_ZERO(nvmem);
+}
+
+static struct platform_driver imx_iim_driver = {
+	.probe	= imx_iim_probe,
+	.driver = {
+		.name	= "imx-iim",
+		.of_match_table = imx_iim_dt_ids,
+	},
+};
+module_platform_driver(imx_iim_driver);
+
+MODULE_AUTHOR("Michael Grzeschik <m.grzeschik@pengutronix.de>");
+MODULE_DESCRIPTION("i.MX IIM driver");
+MODULE_LICENSE("GPL v2");