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, 127 insertions, 0 deletions

diff --git a/drivers/clk/mmp/clk-gate.c b/drivers/clk/mmp/clk-gate.c
new file mode 100644
index 000000000..cc2f841ae
--- /dev/null
+++ b/drivers/clk/mmp/clk-gate.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * mmp gate clock operation source file
+ *
+ * Copyright (C) 2014 Marvell
+ * Chao Xie <chao.xie@marvell.com>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+
+#include "clk.h"
+
+/*
+ * Some clocks will have multiple bits to enable the clocks, and
+ * the bits to disable the clock is not same as enabling bits.
+ */
+
+#define to_clk_mmp_gate(hw)	container_of(hw, struct mmp_clk_gate, hw)
+
+static int mmp_clk_gate_enable(struct clk_hw *hw)
+{
+	struct mmp_clk_gate *gate = to_clk_mmp_gate(hw);
+	unsigned long flags = 0;
+	unsigned long rate;
+	u32 tmp;
+
+	if (gate->lock)
+		spin_lock_irqsave(gate->lock, flags);
+
+	tmp = readl(gate->reg);
+	tmp &= ~gate->mask;
+	tmp |= gate->val_enable;
+	writel(tmp, gate->reg);
+
+	if (gate->lock)
+		spin_unlock_irqrestore(gate->lock, flags);
+
+	if (gate->flags & MMP_CLK_GATE_NEED_DELAY) {
+		rate = clk_hw_get_rate(hw);
+		/* Need delay 2 cycles. */
+		udelay(2000000/rate);
+	}
+
+	return 0;
+}
+
+static void mmp_clk_gate_disable(struct clk_hw *hw)
+{
+	struct mmp_clk_gate *gate = to_clk_mmp_gate(hw);
+	unsigned long flags = 0;
+	u32 tmp;
+
+	if (gate->lock)
+		spin_lock_irqsave(gate->lock, flags);
+
+	tmp = readl(gate->reg);
+	tmp &= ~gate->mask;
+	tmp |= gate->val_disable;
+	writel(tmp, gate->reg);
+
+	if (gate->lock)
+		spin_unlock_irqrestore(gate->lock, flags);
+}
+
+static int mmp_clk_gate_is_enabled(struct clk_hw *hw)
+{
+	struct mmp_clk_gate *gate = to_clk_mmp_gate(hw);
+	unsigned long flags = 0;
+	u32 tmp;
+
+	if (gate->lock)
+		spin_lock_irqsave(gate->lock, flags);
+
+	tmp = readl(gate->reg);
+
+	if (gate->lock)
+		spin_unlock_irqrestore(gate->lock, flags);
+
+	return (tmp & gate->mask) == gate->val_enable;
+}
+
+const struct clk_ops mmp_clk_gate_ops = {
+	.enable = mmp_clk_gate_enable,
+	.disable = mmp_clk_gate_disable,
+	.is_enabled = mmp_clk_gate_is_enabled,
+};
+
+struct clk *mmp_clk_register_gate(struct device *dev, const char *name,
+		const char *parent_name, unsigned long flags,
+		void __iomem *reg, u32 mask, u32 val_enable, u32 val_disable,
+		unsigned int gate_flags, spinlock_t *lock)
+{
+	struct mmp_clk_gate *gate;
+	struct clk *clk;
+	struct clk_init_data init;
+
+	/* allocate the gate */
+	gate = kzalloc_obj(*gate);
+	if (!gate)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &mmp_clk_gate_ops;
+	init.flags = flags;
+	init.parent_names = (parent_name ? &parent_name : NULL);
+	init.num_parents = (parent_name ? 1 : 0);
+
+	/* struct clk_gate assignments */
+	gate->reg = reg;
+	gate->mask = mask;
+	gate->val_enable = val_enable;
+	gate->val_disable = val_disable;
+	gate->flags = gate_flags;
+	gate->lock = lock;
+	gate->hw.init = &init;
+
+	clk = clk_register(dev, &gate->hw);
+
+	if (IS_ERR(clk))
+		kfree(gate);
+
+	return clk;
+}