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, 41 insertions, 0 deletions

diff --git a/drivers/dma/loongson/Kconfig b/drivers/dma/loongson/Kconfig
new file mode 100644
index 000000000..c4e62dce5
--- /dev/null
+++ b/drivers/dma/loongson/Kconfig
@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Loongson DMA controllers drivers
+#
+if MACH_LOONGSON32 || MACH_LOONGSON64 || COMPILE_TEST
+
+config LOONGSON1_APB_DMA
+	tristate "Loongson1 APB DMA support"
+	depends on MACH_LOONGSON32 || COMPILE_TEST
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  This selects support for the APB DMA controller in Loongson1 SoCs,
+	  which is required by Loongson1 NAND and audio support.
+
+config LOONGSON2_APB_DMA
+	tristate "Loongson2 APB DMA support"
+	depends on MACH_LOONGSON64 || COMPILE_TEST
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Support for the Loongson2 APB DMA controller driver. The
+	  DMA controller is having single DMA channel which can be
+	  configured for different peripherals like audio, nand, sdio
+	  etc which is in APB bus.
+
+	  This DMA controller transfers data from memory to peripheral fifo.
+	  It does not support memory to memory data transfer.
+
+config LOONGSON2_APB_CMC_DMA
+	tristate "Loongson2 Chain Multi-Channel DMA support"
+	depends on MACH_LOONGSON64 || COMPILE_TEST
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Support for the Loongson Chain Multi-Channel DMA controller driver.
+	  It is discovered on the Loongson-2K chip (Loongson-2K0300/Loongson-2K3000),
+	  which has 4/8 channels internally, enabling bidirectional data transfer
+	  between devices and memory.
+
+endif