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/misc/smpro-misc.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 144 insertions(+) create mode 100644 drivers/misc/smpro-misc.c (limited to 'drivers/misc/smpro-misc.c') diff --git a/drivers/misc/smpro-misc.c b/drivers/misc/smpro-misc.c new file mode 100644 index 000000000..2ca5e3bcc --- /dev/null +++ b/drivers/misc/smpro-misc.c @@ -0,0 +1,144 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Ampere Computing SoC's SMpro Misc Driver + * + * Copyright (c) 2022, Ampere Computing LLC + */ +#include +#include +#include + +/* Boot Stage/Progress Registers */ +#define BOOTSTAGE 0xB0 +#define BOOTSTAGE_LO 0xB1 +#define CUR_BOOTSTAGE 0xB2 +#define BOOTSTAGE_HI 0xB3 + +/* SOC State Registers */ +#define SOC_POWER_LIMIT 0xE5 + +struct smpro_misc { + struct regmap *regmap; +}; + +static ssize_t boot_progress_show(struct device *dev, struct device_attribute *da, char *buf) +{ + struct smpro_misc *misc = dev_get_drvdata(dev); + u16 boot_progress[3] = { 0 }; + u32 bootstage; + u8 boot_stage; + u8 cur_stage; + u32 reg_lo; + u32 reg; + int ret; + + /* Read current boot stage */ + ret = regmap_read(misc->regmap, CUR_BOOTSTAGE, ®); + if (ret) + return ret; + + cur_stage = reg & 0xff; + + ret = regmap_read(misc->regmap, BOOTSTAGE, &bootstage); + if (ret) + return ret; + + boot_stage = (bootstage >> 8) & 0xff; + + if (boot_stage > cur_stage) + return -EINVAL; + + ret = regmap_read(misc->regmap, BOOTSTAGE_LO, ®_lo); + if (!ret) + ret = regmap_read(misc->regmap, BOOTSTAGE_HI, ®); + if (ret) + return ret; + + /* Firmware to report new boot stage next time */ + if (boot_stage < cur_stage) { + ret = regmap_write(misc->regmap, BOOTSTAGE, ((bootstage & 0xff00) | 0x1)); + if (ret) + return ret; + } + + boot_progress[0] = bootstage; + boot_progress[1] = swab16(reg); + boot_progress[2] = swab16(reg_lo); + + return sysfs_emit(buf, "%*phN\n", (int)sizeof(boot_progress), boot_progress); +} + +static DEVICE_ATTR_RO(boot_progress); + +static ssize_t soc_power_limit_show(struct device *dev, struct device_attribute *da, char *buf) +{ + struct smpro_misc *misc = dev_get_drvdata(dev); + unsigned int value; + int ret; + + ret = regmap_read(misc->regmap, SOC_POWER_LIMIT, &value); + if (ret) + return ret; + + return sysfs_emit(buf, "%d\n", value); +} + +static ssize_t soc_power_limit_store(struct device *dev, struct device_attribute *da, + const char *buf, size_t count) +{ + struct smpro_misc *misc = dev_get_drvdata(dev); + unsigned long val; + s32 ret; + + ret = kstrtoul(buf, 0, &val); + if (ret) + return ret; + + ret = regmap_write(misc->regmap, SOC_POWER_LIMIT, (unsigned int)val); + if (ret) + return -EPROTO; + + return count; +} + +static DEVICE_ATTR_RW(soc_power_limit); + +static struct attribute *smpro_misc_attrs[] = { + &dev_attr_boot_progress.attr, + &dev_attr_soc_power_limit.attr, + NULL +}; + +ATTRIBUTE_GROUPS(smpro_misc); + +static int smpro_misc_probe(struct platform_device *pdev) +{ + struct smpro_misc *misc; + + misc = devm_kzalloc(&pdev->dev, sizeof(struct smpro_misc), GFP_KERNEL); + if (!misc) + return -ENOMEM; + + platform_set_drvdata(pdev, misc); + + misc->regmap = dev_get_regmap(pdev->dev.parent, NULL); + if (!misc->regmap) + return -ENODEV; + + return 0; +} + +static struct platform_driver smpro_misc_driver = { + .probe = smpro_misc_probe, + .driver = { + .name = "smpro-misc", + .dev_groups = smpro_misc_groups, + }, +}; + +module_platform_driver(smpro_misc_driver); + +MODULE_AUTHOR("Tung Nguyen "); +MODULE_AUTHOR("Quan Nguyen "); +MODULE_DESCRIPTION("Ampere Altra SMpro Misc driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1