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/dma/dw/pci.c b/drivers/dma/dw/pci.c
new file mode 100644
index 000000000..a3aae3d1c
--- /dev/null
+++ b/drivers/dma/dw/pci.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PCI driver for the Synopsys DesignWare DMA Controller
+ *
+ * Copyright (C) 2013 Intel Corporation
+ * Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+ */
+
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/device.h>
+
+#include "internal.h"
+
+static int dw_pci_probe(struct pci_dev *pdev, const struct pci_device_id *pid)
+{
+	const struct dw_dma_chip_pdata *drv_data = (void *)pid->driver_data;
+	struct dw_dma_chip_pdata *data;
+	struct dw_dma_chip *chip;
+	int ret;
+
+	ret = pcim_enable_device(pdev);
+	if (ret)
+		return ret;
+
+	ret = pcim_iomap_regions(pdev, 1 << 0, pci_name(pdev));
+	if (ret) {
+		dev_err(&pdev->dev, "I/O memory remapping failed\n");
+		return ret;
+	}
+
+	pci_set_master(pdev);
+	pci_try_set_mwi(pdev);
+
+	ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
+	if (ret)
+		return ret;
+
+	data = devm_kmemdup(&pdev->dev, drv_data, sizeof(*drv_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	chip->dev = &pdev->dev;
+	chip->id = pdev->devfn;
+	chip->regs = pcim_iomap_table(pdev)[0];
+	chip->irq = pdev->irq;
+	chip->pdata = data->pdata;
+
+	data->chip = chip;
+
+	ret = data->probe(chip);
+	if (ret)
+		return ret;
+
+	pci_set_drvdata(pdev, data);
+
+	dw_dma_acpi_controller_register(chip->dw);
+
+	return 0;
+}
+
+static void dw_pci_remove(struct pci_dev *pdev)
+{
+	struct dw_dma_chip_pdata *data = pci_get_drvdata(pdev);
+	struct dw_dma_chip *chip = data->chip;
+	int ret;
+
+	dw_dma_acpi_controller_free(chip->dw);
+
+	ret = data->remove(chip);
+	if (ret)
+		dev_warn(&pdev->dev, "can't remove device properly: %d\n", ret);
+}
+
+static int dw_pci_suspend_late(struct device *dev)
+{
+	struct dw_dma_chip_pdata *data = dev_get_drvdata(dev);
+	struct dw_dma_chip *chip = data->chip;
+
+	return do_dw_dma_disable(chip);
+};
+
+static int dw_pci_resume_early(struct device *dev)
+{
+	struct dw_dma_chip_pdata *data = dev_get_drvdata(dev);
+	struct dw_dma_chip *chip = data->chip;
+
+	return do_dw_dma_enable(chip);
+};
+
+static const struct dev_pm_ops dw_pci_dev_pm_ops = {
+	LATE_SYSTEM_SLEEP_PM_OPS(dw_pci_suspend_late, dw_pci_resume_early)
+};
+
+static const struct pci_device_id dw_pci_id_table[] = {
+	/* Medfield (GPDMA) */
+	{ PCI_VDEVICE(INTEL, 0x0827), (kernel_ulong_t)&dw_dma_chip_pdata },
+
+	/* BayTrail */
+	{ PCI_VDEVICE(INTEL, 0x0f06), (kernel_ulong_t)&dw_dma_chip_pdata },
+	{ PCI_VDEVICE(INTEL, 0x0f40), (kernel_ulong_t)&dw_dma_chip_pdata },
+
+	/* Merrifield */
+	{ PCI_VDEVICE(INTEL, 0x11a2), (kernel_ulong_t)&idma32_chip_pdata },
+
+	/* Braswell */
+	{ PCI_VDEVICE(INTEL, 0x2286), (kernel_ulong_t)&dw_dma_chip_pdata },
+	{ PCI_VDEVICE(INTEL, 0x22c0), (kernel_ulong_t)&dw_dma_chip_pdata },
+
+	/* Elkhart Lake iDMA 32-bit (PSE DMA) */
+	{ PCI_VDEVICE(INTEL, 0x4bb4), (kernel_ulong_t)&xbar_chip_pdata },
+	{ PCI_VDEVICE(INTEL, 0x4bb5), (kernel_ulong_t)&xbar_chip_pdata },
+	{ PCI_VDEVICE(INTEL, 0x4bb6), (kernel_ulong_t)&xbar_chip_pdata },
+
+	/* Haswell */
+	{ PCI_VDEVICE(INTEL, 0x9c60), (kernel_ulong_t)&dw_dma_chip_pdata },
+
+	/* Broadwell */
+	{ PCI_VDEVICE(INTEL, 0x9ce0), (kernel_ulong_t)&dw_dma_chip_pdata },
+
+	{ }
+};
+MODULE_DEVICE_TABLE(pci, dw_pci_id_table);
+
+static struct pci_driver dw_pci_driver = {
+	.name		= "dw_dmac_pci",
+	.id_table	= dw_pci_id_table,
+	.probe		= dw_pci_probe,
+	.remove		= dw_pci_remove,
+	.driver	= {
+		.pm	= pm_sleep_ptr(&dw_pci_dev_pm_ops),
+	},
+};
+
+module_pci_driver(dw_pci_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Synopsys DesignWare DMA Controller PCI driver");
+MODULE_AUTHOR("Andy Shevchenko <andriy.shevchenko@linux.intel.com>");