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, 88 insertions, 0 deletions

diff --git a/drivers/clk/sprd/mux.h b/drivers/clk/sprd/mux.h
new file mode 100644
index 000000000..f3cc31dae
--- /dev/null
+++ b/drivers/clk/sprd/mux.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+//
+// Spreadtrum multiplexer clock driver
+//
+// Copyright (C) 2017 Spreadtrum, Inc.
+// Author: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
+
+#ifndef _SPRD_MUX_H_
+#define _SPRD_MUX_H_
+
+#include "common.h"
+
+/**
+ * struct sprd_mux_ssel - Mux clock's source select bits in its register
+ * @shift: Bit offset of the divider in its register
+ * @width: Width of the divider field in its register
+ * @table: For some mux clocks, not all sources are used on some special
+ *	   chips, this matches the value of mux clock's register and the
+ *	   sources which are used for this mux clock
+ */
+struct sprd_mux_ssel {
+	u8		shift;
+	u8		width;
+	const u8	*table;
+};
+
+struct sprd_mux {
+	struct sprd_mux_ssel mux;
+	struct sprd_clk_common	common;
+};
+
+#define _SPRD_MUX_CLK(_shift, _width, _table)		\
+	{						\
+		.shift	= _shift,			\
+		.width	= _width,			\
+		.table	= _table,			\
+	}
+
+#define SPRD_MUX_CLK_HW_INIT_FN(_struct, _name, _parents, _table,	\
+				_reg, _shift, _width, _flags, _fn)	\
+	struct sprd_mux _struct = {					\
+		.mux	= _SPRD_MUX_CLK(_shift, _width, _table),	\
+		.common	= {						\
+			.regmap		= NULL,				\
+			.reg		= _reg,				\
+			.hw.init = _fn(_name, _parents,			\
+				       &sprd_mux_ops, _flags),		\
+		}							\
+	}
+
+#define SPRD_MUX_CLK_TABLE(_struct, _name, _parents, _table,		\
+			   _reg, _shift, _width, _flags)		\
+	SPRD_MUX_CLK_HW_INIT_FN(_struct, _name, _parents, _table,	\
+				_reg, _shift, _width, _flags,		\
+				CLK_HW_INIT_PARENTS)
+
+#define SPRD_MUX_CLK(_struct, _name, _parents, _reg,		\
+		     _shift, _width, _flags)			\
+	SPRD_MUX_CLK_TABLE(_struct, _name, _parents, NULL,	\
+			   _reg, _shift, _width, _flags)
+
+#define SPRD_MUX_CLK_DATA_TABLE(_struct, _name, _parents, _table,	\
+				_reg, _shift, _width, _flags)		\
+	SPRD_MUX_CLK_HW_INIT_FN(_struct, _name, _parents, _table,	\
+				_reg, _shift, _width, _flags,		\
+				CLK_HW_INIT_PARENTS_DATA)
+
+#define SPRD_MUX_CLK_DATA(_struct, _name, _parents, _reg,		\
+			  _shift, _width, _flags)			\
+	SPRD_MUX_CLK_DATA_TABLE(_struct, _name, _parents, NULL,		\
+				_reg, _shift, _width, _flags)
+
+static inline struct sprd_mux *hw_to_sprd_mux(const struct clk_hw *hw)
+{
+	struct sprd_clk_common *common = hw_to_sprd_clk_common(hw);
+
+	return container_of(common, struct sprd_mux, common);
+}
+
+extern const struct clk_ops sprd_mux_ops;
+
+u8 sprd_mux_helper_get_parent(const struct sprd_clk_common *common,
+			      const struct sprd_mux_ssel *mux);
+int sprd_mux_helper_set_parent(const struct sprd_clk_common *common,
+			       const struct sprd_mux_ssel *mux,
+			       u8 index);
+
+#endif /* _SPRD_MUX_H_ */