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, 80 insertions, 0 deletions

diff --git a/drivers/fpga/versal-fpga.c b/drivers/fpga/versal-fpga.c
new file mode 100644
index 000000000..e6189106c
--- /dev/null
+++ b/drivers/fpga/versal-fpga.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019-2021 Xilinx, Inc.
+ */
+
+#include <linux/dma-mapping.h>
+#include <linux/fpga/fpga-mgr.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/string.h>
+#include <linux/firmware/xlnx-zynqmp.h>
+
+static int versal_fpga_ops_write_init(struct fpga_manager *mgr,
+				      struct fpga_image_info *info,
+				      const char *buf, size_t size)
+{
+	return 0;
+}
+
+static int versal_fpga_ops_write(struct fpga_manager *mgr,
+				 const char *buf, size_t size)
+{
+	dma_addr_t dma_addr = 0;
+	char *kbuf;
+	int ret;
+
+	kbuf = dma_alloc_coherent(mgr->dev.parent, size, &dma_addr, GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	memcpy(kbuf, buf, size);
+	ret = zynqmp_pm_load_pdi(PDI_SRC_DDR, dma_addr);
+	dma_free_coherent(mgr->dev.parent, size, kbuf, dma_addr);
+
+	return ret;
+}
+
+static const struct fpga_manager_ops versal_fpga_ops = {
+	.write_init = versal_fpga_ops_write_init,
+	.write = versal_fpga_ops_write,
+};
+
+static int versal_fpga_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct fpga_manager *mgr;
+	int ret;
+
+	ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(44));
+	if (ret < 0) {
+		dev_err(dev, "no usable DMA configuration\n");
+		return ret;
+	}
+
+	mgr = devm_fpga_mgr_register(dev, "Xilinx Versal FPGA Manager",
+				     &versal_fpga_ops, NULL);
+	return PTR_ERR_OR_ZERO(mgr);
+}
+
+static const struct of_device_id versal_fpga_of_match[] = {
+	{ .compatible = "xlnx,versal-fpga", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, versal_fpga_of_match);
+
+static struct platform_driver versal_fpga_driver = {
+	.probe = versal_fpga_probe,
+	.driver = {
+		.name = "versal_fpga_manager",
+		.of_match_table = versal_fpga_of_match,
+	},
+};
+module_platform_driver(versal_fpga_driver);
+
+MODULE_AUTHOR("Nava kishore Manne <nava.manne@xilinx.com>");
+MODULE_AUTHOR("Appana Durga Kedareswara rao <appanad.durga.rao@xilinx.com>");
+MODULE_DESCRIPTION("Xilinx Versal FPGA Manager");
+MODULE_LICENSE("GPL");