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/mfd/stm32-lptimer.c | 133 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 133 insertions(+) create mode 100644 drivers/mfd/stm32-lptimer.c (limited to 'drivers/mfd/stm32-lptimer.c') diff --git a/drivers/mfd/stm32-lptimer.c b/drivers/mfd/stm32-lptimer.c new file mode 100644 index 000000000..123659178 --- /dev/null +++ b/drivers/mfd/stm32-lptimer.c @@ -0,0 +1,133 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * STM32 Low-Power Timer parent driver. + * Copyright (C) STMicroelectronics 2017 + * Author: Fabrice Gasnier + * Inspired by Benjamin Gaignard's stm32-timers driver + */ + +#include +#include +#include +#include +#include + +#define STM32_LPTIM_MAX_REGISTER 0x3fc + +static const struct regmap_config stm32_lptimer_regmap_cfg = { + .reg_bits = 32, + .val_bits = 32, + .reg_stride = sizeof(u32), + .max_register = STM32_LPTIM_MAX_REGISTER, +}; + +static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata) +{ + u32 val; + int ret; + + /* + * Quadrature encoder mode bit can only be written and read back when + * Low-Power Timer supports it. + */ + ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR, + STM32_LPTIM_ENC, STM32_LPTIM_ENC); + if (ret) + return ret; + + ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val); + if (ret) + return ret; + + ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR, + STM32_LPTIM_ENC, 0); + if (ret) + return ret; + + ddata->has_encoder = !!(val & STM32_LPTIM_ENC); + + return 0; +} + +static int stm32_lptimer_detect_hwcfgr(struct stm32_lptimer *ddata) +{ + u32 val; + int ret; + + ret = regmap_read(ddata->regmap, STM32_LPTIM_VERR, &ddata->version); + if (ret) + return ret; + + /* Try to guess parameters from HWCFGR: e.g. encoder mode (STM32MP15) */ + ret = regmap_read(ddata->regmap, STM32_LPTIM_HWCFGR1, &val); + if (ret) + return ret; + + /* Fallback to legacy init if HWCFGR isn't present */ + if (!val) + return stm32_lptimer_detect_encoder(ddata); + + ddata->has_encoder = FIELD_GET(STM32_LPTIM_HWCFGR1_ENCODER, val); + + ret = regmap_read(ddata->regmap, STM32_LPTIM_HWCFGR2, &val); + if (ret) + return ret; + + /* Number of capture/compare channels */ + ddata->num_cc_chans = FIELD_GET(STM32_LPTIM_HWCFGR2_CHAN_NUM, val); + + return 0; +} + +static int stm32_lptimer_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct stm32_lptimer *ddata; + void __iomem *mmio; + int ret; + + ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL); + if (!ddata) + return -ENOMEM; + + mmio = devm_platform_get_and_ioremap_resource(pdev, 0, NULL); + if (IS_ERR(mmio)) + return PTR_ERR(mmio); + + ddata->regmap = devm_regmap_init_mmio_clk(dev, "mux", mmio, + &stm32_lptimer_regmap_cfg); + if (IS_ERR(ddata->regmap)) + return PTR_ERR(ddata->regmap); + + ddata->clk = devm_clk_get(dev, NULL); + if (IS_ERR(ddata->clk)) + return PTR_ERR(ddata->clk); + + ret = stm32_lptimer_detect_hwcfgr(ddata); + if (ret) + return ret; + + platform_set_drvdata(pdev, ddata); + + return devm_of_platform_populate(&pdev->dev); +} + +static const struct of_device_id stm32_lptimer_of_match[] = { + { .compatible = "st,stm32-lptimer", }, + {}, +}; +MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match); + +static struct platform_driver stm32_lptimer_driver = { + .probe = stm32_lptimer_probe, + .driver = { + .name = "stm32-lptimer", + .of_match_table = stm32_lptimer_of_match, + }, +}; +module_platform_driver(stm32_lptimer_driver); + +MODULE_AUTHOR("Fabrice Gasnier "); +MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer"); +MODULE_ALIAS("platform:stm32-lptimer"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1