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, 127 insertions, 0 deletions

diff --git a/drivers/mfd/bcm2835-pm.c b/drivers/mfd/bcm2835-pm.c
new file mode 100644
index 000000000..9e8e3dcf4
--- /dev/null
+++ b/drivers/mfd/bcm2835-pm.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * PM MFD driver for Broadcom BCM2835
+ *
+ * This driver binds to the PM block and creates the MFD device for
+ * the WDT and power drivers.
+ */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/mfd/bcm2835-pm.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+static const struct mfd_cell bcm2835_pm_devs[] = {
+	{ .name = "bcm2835-wdt" },
+};
+
+static const struct mfd_cell bcm2835_power_devs[] = {
+	{ .name = "bcm2835-power" },
+};
+
+static int bcm2835_pm_get_pdata(struct platform_device *pdev,
+				struct bcm2835_pm *pm)
+{
+	if (of_property_present(pm->dev->of_node, "reg-names")) {
+		struct resource *res;
+
+		pm->base = devm_platform_ioremap_resource_byname(pdev, "pm");
+		if (IS_ERR(pm->base))
+			return PTR_ERR(pm->base);
+
+		res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "asb");
+		if (res) {
+			pm->asb = devm_ioremap_resource(&pdev->dev, res);
+			if (IS_ERR(pm->asb))
+				pm->asb = NULL;
+		}
+
+		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+						    "rpivid_asb");
+		if (res) {
+			pm->rpivid_asb = devm_ioremap_resource(&pdev->dev, res);
+			if (IS_ERR(pm->rpivid_asb))
+				pm->rpivid_asb = NULL;
+		}
+
+		return 0;
+	}
+
+	/* If no 'reg-names' property is found we can assume we're using old DTB. */
+	pm->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(pm->base))
+		return PTR_ERR(pm->base);
+
+	pm->asb = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(pm->asb))
+		pm->asb = NULL;
+
+	pm->rpivid_asb = devm_platform_ioremap_resource(pdev, 2);
+	if (IS_ERR(pm->rpivid_asb))
+		pm->rpivid_asb = NULL;
+
+	return 0;
+}
+
+static int bcm2835_pm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct bcm2835_pm *pm;
+	int ret;
+
+	pm = devm_kzalloc(dev, sizeof(*pm), GFP_KERNEL);
+	if (!pm)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, pm);
+
+	pm->dev = dev;
+	pm->soc = (uintptr_t)device_get_match_data(dev);
+
+	ret = bcm2835_pm_get_pdata(pdev, pm);
+	if (ret)
+		return ret;
+
+	ret = devm_mfd_add_devices(dev, -1,
+				   bcm2835_pm_devs, ARRAY_SIZE(bcm2835_pm_devs),
+				   NULL, 0, NULL);
+	if (ret)
+		return ret;
+
+	/*
+	 * We'll use the presence of the AXI ASB regs in the
+	 * bcm2835-pm binding as the key for whether we can reference
+	 * the full PM register range and support power domains.
+	 */
+	if (pm->asb || pm->soc == BCM2835_PM_SOC_BCM2712)
+		return devm_mfd_add_devices(dev, -1, bcm2835_power_devs,
+					    ARRAY_SIZE(bcm2835_power_devs),
+					    NULL, 0, NULL);
+	return 0;
+}
+
+static const struct of_device_id bcm2835_pm_of_match[] = {
+	{ .compatible = "brcm,bcm2835-pm-wdt", },
+	{ .compatible = "brcm,bcm2835-pm", .data = (void *)BCM2835_PM_SOC_BCM2835 },
+	{ .compatible = "brcm,bcm2711-pm", .data = (void *)BCM2835_PM_SOC_BCM2711 },
+	{ .compatible = "brcm,bcm2712-pm", .data = (void *)BCM2835_PM_SOC_BCM2712 },
+	{},
+};
+MODULE_DEVICE_TABLE(of, bcm2835_pm_of_match);
+
+static struct platform_driver bcm2835_pm_driver = {
+	.probe		= bcm2835_pm_probe,
+	.driver = {
+		.name =	"bcm2835-pm",
+		.of_match_table = bcm2835_pm_of_match,
+	},
+};
+module_platform_driver(bcm2835_pm_driver);
+
+MODULE_AUTHOR("Eric Anholt <eric@anholt.net>");
+MODULE_DESCRIPTION("Driver for Broadcom BCM2835 PM MFD");