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, 52 insertions, 0 deletions

diff --git a/drivers/acpi/arm64/dma.c b/drivers/acpi/arm64/dma.c
new file mode 100644
index 000000000..f30f13835
--- /dev/null
+++ b/drivers/acpi/arm64/dma.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/acpi.h>
+#include <linux/acpi_iort.h>
+#include <linux/device.h>
+#include <linux/dma-direct.h>
+
+void acpi_arch_dma_setup(struct device *dev)
+{
+	int ret;
+	u64 end, mask;
+	const struct bus_dma_region *map = NULL;
+
+	/*
+	 * If @dev is expected to be DMA-capable then the bus code that created
+	 * it should have initialised its dma_mask pointer by this point. For
+	 * now, we'll continue the legacy behaviour of coercing it to the
+	 * coherent mask if not, but we'll no longer do so quietly.
+	 */
+	if (!dev->dma_mask) {
+		dev_warn(dev, "DMA mask not set\n");
+		dev->dma_mask = &dev->coherent_dma_mask;
+	}
+
+	if (dev->coherent_dma_mask)
+		end = dev->coherent_dma_mask;
+	else
+		end = (1ULL << 32) - 1;
+
+	if (dev->dma_range_map) {
+		dev_dbg(dev, "dma_range_map already set\n");
+		return;
+	}
+
+	ret = acpi_dma_get_range(dev, &map);
+	if (!ret && map) {
+		end = dma_range_map_max(map);
+		dev->dma_range_map = map;
+	}
+
+	if (ret == -ENODEV)
+		ret = iort_dma_get_ranges(dev, &end);
+	if (!ret) {
+		/*
+		 * Limit coherent and dma mask based on size retrieved from
+		 * firmware.
+		 */
+		mask = DMA_BIT_MASK(ilog2(end) + 1);
+		dev->bus_dma_limit = end;
+		dev->coherent_dma_mask = min(dev->coherent_dma_mask, mask);
+		*dev->dma_mask = min(*dev->dma_mask, mask);
+	}
+}