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/at91-usart.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 drivers/mfd/at91-usart.c (limited to 'drivers/mfd/at91-usart.c') diff --git a/drivers/mfd/at91-usart.c b/drivers/mfd/at91-usart.c new file mode 100644 index 000000000..7f08cb60c --- /dev/null +++ b/drivers/mfd/at91-usart.c @@ -0,0 +1,68 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Driver for AT91 USART + * + * Copyright (C) 2018 Microchip Technology + * + * Author: Radu Pirea + * + */ + +#include + +#include +#include +#include +#include + +static const struct mfd_cell at91_usart_spi_subdev = + MFD_CELL_NAME("at91_usart_spi"); + +static const struct mfd_cell at91_usart_serial_subdev = + MFD_CELL_NAME("atmel_usart_serial"); + +static int at91_usart_mode_probe(struct platform_device *pdev) +{ + const struct mfd_cell *cell; + u32 opmode = AT91_USART_MODE_SERIAL; + + device_property_read_u32(&pdev->dev, "atmel,usart-mode", &opmode); + + switch (opmode) { + case AT91_USART_MODE_SPI: + cell = &at91_usart_spi_subdev; + break; + case AT91_USART_MODE_SERIAL: + cell = &at91_usart_serial_subdev; + break; + default: + dev_err(&pdev->dev, "atmel,usart-mode has an invalid value %u\n", + opmode); + return -EINVAL; + } + + return devm_mfd_add_devices(&pdev->dev, PLATFORM_DEVID_AUTO, cell, 1, + NULL, 0, NULL); +} + +static const struct of_device_id at91_usart_mode_of_match[] = { + { .compatible = "atmel,at91rm9200-usart" }, + { .compatible = "atmel,at91sam9260-usart" }, + { /* sentinel */ } +}; + +MODULE_DEVICE_TABLE(of, at91_usart_mode_of_match); + +static struct platform_driver at91_usart_mfd = { + .probe = at91_usart_mode_probe, + .driver = { + .name = "at91_usart_mode", + .of_match_table = at91_usart_mode_of_match, + }, +}; + +module_platform_driver(at91_usart_mfd); + +MODULE_AUTHOR("Radu Pirea "); +MODULE_DESCRIPTION("AT91 USART MFD driver"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1