bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 59 insertions, 0 deletions

diff --git a/drivers/clk/qcom/reset.c b/drivers/clk/qcom/reset.c
new file mode 100644
index 000000000..d96c96a90
--- /dev/null
+++ b/drivers/clk/qcom/reset.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2013, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/bitops.h>
+#include <linux/export.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+#include <linux/delay.h>
+
+#include "reset.h"
+
+static int qcom_reset(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct qcom_reset_controller *rst = to_qcom_reset_controller(rcdev);
+
+	rcdev->ops->assert(rcdev, id);
+	fsleep(rst->reset_map[id].udelay ?: 1); /* use 1 us as default */
+
+	rcdev->ops->deassert(rcdev, id);
+	return 0;
+}
+
+static int qcom_reset_set_assert(struct reset_controller_dev *rcdev,
+				 unsigned long id, bool assert)
+{
+	struct qcom_reset_controller *rst;
+	const struct qcom_reset_map *map;
+	u32 mask;
+
+	rst = to_qcom_reset_controller(rcdev);
+	map = &rst->reset_map[id];
+	mask = map->bitmask ? map->bitmask : BIT(map->bit);
+
+	regmap_update_bits(rst->regmap, map->reg, mask, assert ? mask : 0);
+
+	/* Read back the register to ensure write completion, ignore the value */
+	regmap_read(rst->regmap, map->reg, &mask);
+
+	return 0;
+}
+
+static int qcom_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	return qcom_reset_set_assert(rcdev, id, true);
+}
+
+static int qcom_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	return qcom_reset_set_assert(rcdev, id, false);
+}
+
+const struct reset_control_ops qcom_reset_ops = {
+	.reset = qcom_reset,
+	.assert = qcom_reset_assert,
+	.deassert = qcom_reset_deassert,
+};
+EXPORT_SYMBOL_GPL(qcom_reset_ops);