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, 51 insertions, 0 deletions

diff --git a/drivers/clk/st/clkgen.h b/drivers/clk/st/clkgen.h
new file mode 100644
index 000000000..44302fc7c
--- /dev/null
+++ b/drivers/clk/st/clkgen.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/************************************************************************
+File  : Clock H/w specific Information
+
+Author: Pankaj Dev <pankaj.dev@st.com>
+
+Copyright (C) 2014 STMicroelectronics
+************************************************************************/
+
+#ifndef __CLKGEN_INFO_H
+#define __CLKGEN_INFO_H
+
+extern spinlock_t clkgen_a9_lock;
+
+struct clkgen_field {
+	unsigned int offset;
+	unsigned int mask;
+	unsigned int shift;
+};
+
+static inline unsigned long clkgen_read(void __iomem	*base,
+					  struct clkgen_field *field)
+{
+	return (readl(base + field->offset) >> field->shift) & field->mask;
+}
+
+
+static inline void clkgen_write(void __iomem *base, struct clkgen_field *field,
+				  unsigned long val)
+{
+	writel((readl(base + field->offset) &
+	       ~(field->mask << field->shift)) | (val << field->shift),
+	       base + field->offset);
+
+	return;
+}
+
+#define CLKGEN_FIELD(_offset, _mask, _shift) {		\
+				.offset	= _offset,	\
+				.mask	= _mask,	\
+				.shift	= _shift,	\
+				}
+
+#define CLKGEN_READ(pll, field) clkgen_read(pll->regs_base, \
+		&pll->data->field)
+
+#define CLKGEN_WRITE(pll, field, val) clkgen_write(pll->regs_base, \
+		&pll->data->field, val)
+
+#endif /*__CLKGEN_INFO_H*/
+