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, 147 insertions, 0 deletions

diff --git a/drivers/mfd/bq257xx.c b/drivers/mfd/bq257xx.c
new file mode 100644
index 000000000..054342c60
--- /dev/null
+++ b/drivers/mfd/bq257xx.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * BQ257XX Core Driver
+ * Copyright (C) 2025 Chris Morgan <macromorgan@hotmail.com>
+ */
+
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/mfd/bq257xx.h>
+#include <linux/mfd/core.h>
+#include <linux/regmap.h>
+
+static const struct regmap_range bq25703_readonly_reg_ranges[] = {
+	regmap_reg_range(BQ25703_CHARGER_STATUS, BQ25703_MANUFACT_DEV_ID),
+};
+
+static const struct regmap_access_table bq25703_writeable_regs = {
+	.no_ranges = bq25703_readonly_reg_ranges,
+	.n_no_ranges = ARRAY_SIZE(bq25703_readonly_reg_ranges),
+};
+
+static const struct regmap_range bq25703_volatile_reg_ranges[] = {
+	regmap_reg_range(BQ25703_CHARGE_OPTION_0, BQ25703_IIN_HOST),
+	regmap_reg_range(BQ25703_CHARGER_STATUS, BQ25703_ADC_OPTION),
+};
+
+static const struct regmap_access_table bq25703_volatile_regs = {
+	.yes_ranges = bq25703_volatile_reg_ranges,
+	.n_yes_ranges = ARRAY_SIZE(bq25703_volatile_reg_ranges),
+};
+
+static const struct regmap_config bq25703_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 16,
+	.max_register = BQ25703_ADC_OPTION,
+	.cache_type = REGCACHE_MAPLE,
+	.wr_table = &bq25703_writeable_regs,
+	.volatile_table = &bq25703_volatile_regs,
+	.val_format_endian = REGMAP_ENDIAN_LITTLE,
+};
+
+static const struct regmap_range bq25792_writeable_reg_ranges[] = {
+	regmap_reg_range(BQ25792_REG00_MIN_SYS_VOLTAGE,
+			 BQ25792_REG18_NTC_CONTROL_1),
+	regmap_reg_range(BQ25792_REG28_CHARGER_MASK_0,
+			 BQ25792_REG30_ADC_FUNCTION_DISABLE_1),
+};
+
+static const struct regmap_access_table bq25792_writeable_regs = {
+	.yes_ranges = bq25792_writeable_reg_ranges,
+	.n_yes_ranges = ARRAY_SIZE(bq25792_writeable_reg_ranges),
+};
+
+static const struct regmap_range bq25792_volatile_reg_ranges[] = {
+	regmap_reg_range(BQ25792_REG19_ICO_CURRENT_LIMIT,
+			 BQ25792_REG27_FAULT_FLAG_1),
+	regmap_reg_range(BQ25792_REG31_IBUS_ADC,
+			 BQ25792_REG47_DPDM_DRIVER),
+};
+
+static const struct regmap_access_table bq25792_volatile_regs = {
+	.yes_ranges = bq25792_volatile_reg_ranges,
+	.n_yes_ranges = ARRAY_SIZE(bq25792_volatile_reg_ranges),
+};
+
+static const struct regmap_config bq25792_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = BQ25792_REG48_PART_INFORMATION,
+	.cache_type = REGCACHE_MAPLE,
+	.wr_table = &bq25792_writeable_regs,
+	.volatile_table = &bq25792_volatile_regs,
+};
+
+static const struct mfd_cell cells[] = {
+	MFD_CELL_NAME("bq257xx-regulator"),
+	MFD_CELL_NAME("bq257xx-charger"),
+};
+
+static int bq257xx_probe(struct i2c_client *client)
+{
+	const struct regmap_config *rcfg;
+	struct bq257xx_device *ddata;
+	int ret;
+
+	ddata = devm_kzalloc(&client->dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata)
+		return -ENOMEM;
+
+	ddata->type = (uintptr_t)i2c_get_match_data(client);
+	ddata->client = client;
+
+	switch (ddata->type) {
+	case BQ25703A:
+		rcfg = &bq25703_regmap_config;
+		break;
+	case BQ25792:
+		rcfg = &bq25792_regmap_config;
+		break;
+	default:
+		return dev_err_probe(&client->dev, -ENODEV, "Unsupported device type\n");
+	}
+
+	ddata->regmap = devm_regmap_init_i2c(client, rcfg);
+	if (IS_ERR(ddata->regmap)) {
+		return dev_err_probe(&client->dev, PTR_ERR(ddata->regmap),
+				     "Failed to allocate register map\n");
+	}
+
+	i2c_set_clientdata(client, ddata);
+
+	ret = devm_mfd_add_devices(&client->dev, PLATFORM_DEVID_AUTO,
+				   cells, ARRAY_SIZE(cells), NULL, 0, NULL);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Failed to register child devices\n");
+
+	return ret;
+}
+
+static const struct i2c_device_id bq257xx_i2c_ids[] = {
+	{ "bq25703a", BQ25703A },
+	{ "bq25792", BQ25792 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, bq257xx_i2c_ids);
+
+static const struct of_device_id bq257xx_of_match[] = {
+	{ .compatible = "ti,bq25703a", .data = (void *)BQ25703A },
+	{ .compatible = "ti,bq25792", .data = (void *)BQ25792 },
+	{}
+};
+MODULE_DEVICE_TABLE(of, bq257xx_of_match);
+
+static struct i2c_driver bq257xx_driver = {
+	.driver = {
+		.name = "bq257xx",
+		.of_match_table = bq257xx_of_match,
+	},
+	.probe = bq257xx_probe,
+	.id_table = bq257xx_i2c_ids,
+};
+module_i2c_driver(bq257xx_driver);
+
+MODULE_DESCRIPTION("bq257xx buck/boost/charger driver");
+MODULE_AUTHOR("Chris Morgan <macromorgan@hotmail.com>");
+MODULE_LICENSE("GPL");