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, 126 insertions, 0 deletions

diff --git a/drivers/clk/rockchip/softrst.c b/drivers/clk/rockchip/softrst.c
new file mode 100644
index 000000000..115f317a9
--- /dev/null
+++ b/drivers/clk/rockchip/softrst.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2014 MundoReader S.L.
+ * Author: Heiko Stuebner <heiko@sntech.de>
+ */
+
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/reset-controller.h>
+#include <linux/spinlock.h>
+#include "clk.h"
+
+struct rockchip_softrst {
+	struct reset_controller_dev	rcdev;
+	const int			*lut;
+	void __iomem			*reg_base;
+	int				num_regs;
+	int				num_per_reg;
+	u8				flags;
+	spinlock_t			lock;
+};
+
+static int rockchip_softrst_assert(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	struct rockchip_softrst *softrst = container_of(rcdev,
+						     struct rockchip_softrst,
+						     rcdev);
+	int bank, offset;
+
+	if (softrst->lut)
+		id = softrst->lut[id];
+
+	bank = id / softrst->num_per_reg;
+	offset = id % softrst->num_per_reg;
+
+	if (softrst->flags & ROCKCHIP_SOFTRST_HIWORD_MASK) {
+		writel(BIT(offset) | (BIT(offset) << 16),
+		       softrst->reg_base + (bank * 4));
+	} else {
+		unsigned long flags;
+		u32 reg;
+
+		spin_lock_irqsave(&softrst->lock, flags);
+
+		reg = readl(softrst->reg_base + (bank * 4));
+		writel(reg | BIT(offset), softrst->reg_base + (bank * 4));
+
+		spin_unlock_irqrestore(&softrst->lock, flags);
+	}
+
+	return 0;
+}
+
+static int rockchip_softrst_deassert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct rockchip_softrst *softrst = container_of(rcdev,
+						     struct rockchip_softrst,
+						     rcdev);
+	int bank, offset;
+
+	if (softrst->lut)
+		id = softrst->lut[id];
+
+	bank = id / softrst->num_per_reg;
+	offset = id % softrst->num_per_reg;
+
+	if (softrst->flags & ROCKCHIP_SOFTRST_HIWORD_MASK) {
+		writel((BIT(offset) << 16), softrst->reg_base + (bank * 4));
+	} else {
+		unsigned long flags;
+		u32 reg;
+
+		spin_lock_irqsave(&softrst->lock, flags);
+
+		reg = readl(softrst->reg_base + (bank * 4));
+		writel(reg & ~BIT(offset), softrst->reg_base + (bank * 4));
+
+		spin_unlock_irqrestore(&softrst->lock, flags);
+	}
+
+	return 0;
+}
+
+static const struct reset_control_ops rockchip_softrst_ops = {
+	.assert		= rockchip_softrst_assert,
+	.deassert	= rockchip_softrst_deassert,
+};
+
+void rockchip_register_softrst_lut(struct device_node *np,
+				   const int *lookup_table,
+				   unsigned int num_regs,
+				   void __iomem *base, u8 flags)
+{
+	struct rockchip_softrst *softrst;
+	int ret;
+
+	softrst = kzalloc_obj(*softrst);
+	if (!softrst)
+		return;
+
+	spin_lock_init(&softrst->lock);
+
+	softrst->reg_base = base;
+	softrst->lut = lookup_table;
+	softrst->flags = flags;
+	softrst->num_regs = num_regs;
+	softrst->num_per_reg = (flags & ROCKCHIP_SOFTRST_HIWORD_MASK) ? 16
+								      : 32;
+
+	softrst->rcdev.owner = THIS_MODULE;
+	if (lookup_table)
+		softrst->rcdev.nr_resets = num_regs;
+	else
+		softrst->rcdev.nr_resets = num_regs * softrst->num_per_reg;
+	softrst->rcdev.ops = &rockchip_softrst_ops;
+	softrst->rcdev.of_node = np;
+	ret = reset_controller_register(&softrst->rcdev);
+	if (ret) {
+		pr_err("%s: could not register reset controller, %d\n",
+		       __func__, ret);
+		kfree(softrst);
+	}
+};
+EXPORT_SYMBOL_GPL(rockchip_register_softrst_lut);