From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock 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 Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- drivers/hwmon/gxp-fan-ctrl.c | 150 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 150 insertions(+) create mode 100644 drivers/hwmon/gxp-fan-ctrl.c (limited to 'drivers/hwmon/gxp-fan-ctrl.c') diff --git a/drivers/hwmon/gxp-fan-ctrl.c b/drivers/hwmon/gxp-fan-ctrl.c new file mode 100644 index 000000000..64f85d7e7 --- /dev/null +++ b/drivers/hwmon/gxp-fan-ctrl.c @@ -0,0 +1,150 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (C) 2023 Hewlett-Packard Enterprise Development Company, L.P. */ + +#include +#include +#include +#include +#include + +struct gxp_fan_ctrl_drvdata { + void __iomem *base; +}; + +static int gxp_pwm_write(struct device *dev, u32 attr, int channel, long val) +{ + struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev); + + switch (attr) { + case hwmon_pwm_input: + if (val > 255 || val < 0) + return -EINVAL; + writeb(val, drvdata->base + channel); + return 0; + default: + return -EOPNOTSUPP; + } +} + +static int gxp_fan_ctrl_write(struct device *dev, enum hwmon_sensor_types type, + u32 attr, int channel, long val) +{ + switch (type) { + case hwmon_pwm: + return gxp_pwm_write(dev, attr, channel, val); + default: + return -EOPNOTSUPP; + } +} + +static int gxp_pwm_read(struct device *dev, u32 attr, int channel, long *val) +{ + struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev); + + *val = readb(drvdata->base + channel); + + return 0; +} + +static int gxp_fan_ctrl_read(struct device *dev, enum hwmon_sensor_types type, + u32 attr, int channel, long *val) +{ + switch (type) { + case hwmon_pwm: + return gxp_pwm_read(dev, attr, channel, val); + default: + return -EOPNOTSUPP; + } +} + +static umode_t gxp_fan_ctrl_is_visible(const void *_data, + enum hwmon_sensor_types type, + u32 attr, int channel) +{ + umode_t mode = 0; + + switch (type) { + case hwmon_pwm: + switch (attr) { + case hwmon_pwm_input: + mode = 0644; + break; + default: + break; + } + break; + default: + break; + } + + return mode; +} + +static const struct hwmon_ops gxp_fan_ctrl_ops = { + .is_visible = gxp_fan_ctrl_is_visible, + .read = gxp_fan_ctrl_read, + .write = gxp_fan_ctrl_write, +}; + +static const struct hwmon_channel_info * const gxp_fan_ctrl_info[] = { + HWMON_CHANNEL_INFO(pwm, + HWMON_PWM_INPUT, + HWMON_PWM_INPUT, + HWMON_PWM_INPUT, + HWMON_PWM_INPUT, + HWMON_PWM_INPUT, + HWMON_PWM_INPUT, + HWMON_PWM_INPUT, + HWMON_PWM_INPUT), + NULL +}; + +static const struct hwmon_chip_info gxp_fan_ctrl_chip_info = { + .ops = &gxp_fan_ctrl_ops, + .info = gxp_fan_ctrl_info, + +}; + +static int gxp_fan_ctrl_probe(struct platform_device *pdev) +{ + struct gxp_fan_ctrl_drvdata *drvdata; + struct device *dev = &pdev->dev; + struct device *hwmon_dev; + + drvdata = devm_kzalloc(dev, sizeof(struct gxp_fan_ctrl_drvdata), + GFP_KERNEL); + if (!drvdata) + return -ENOMEM; + + drvdata->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL); + if (IS_ERR(drvdata->base)) + return dev_err_probe(dev, PTR_ERR(drvdata->base), + "failed to map base\n"); + + hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev, + "hpe_gxp_fan_ctrl", + drvdata, + &gxp_fan_ctrl_chip_info, + NULL); + + return PTR_ERR_OR_ZERO(hwmon_dev); +} + +static const struct of_device_id gxp_fan_ctrl_of_match[] = { + { .compatible = "hpe,gxp-fan-ctrl", }, + {}, +}; +MODULE_DEVICE_TABLE(of, gxp_fan_ctrl_of_match); + +static struct platform_driver gxp_fan_ctrl_driver = { + .probe = gxp_fan_ctrl_probe, + .driver = { + .name = "gxp-fan-ctrl", + .of_match_table = gxp_fan_ctrl_of_match, + }, +}; +module_platform_driver(gxp_fan_ctrl_driver); + +MODULE_AUTHOR("Nick Hawkins "); +MODULE_DESCRIPTION("HPE GXP fan controller"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1