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/ibmasm/uart.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 drivers/misc/ibmasm/uart.c (limited to 'drivers/misc/ibmasm/uart.c') diff --git a/drivers/misc/ibmasm/uart.c b/drivers/misc/ibmasm/uart.c new file mode 100644 index 000000000..a5d4c8e01 --- /dev/null +++ b/drivers/misc/ibmasm/uart.c @@ -0,0 +1,58 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +/* + * IBM ASM Service Processor Device Driver + * + * Copyright (C) IBM Corporation, 2004 + * + * Author: Max Asböck + */ + +#include +#include +#include +#include +#include +#include "ibmasm.h" +#include "lowlevel.h" + + +void ibmasm_register_uart(struct service_processor *sp) +{ + struct uart_8250_port uart; + void __iomem *iomem_base; + + iomem_base = sp->base_address + SCOUT_COM_B_BASE; + + /* read the uart scratch register to determine if the UART + * is dedicated to the service processor or if the OS can use it + */ + if (0 == readl(iomem_base + UART_SCR)) { + dev_info(sp->dev, "IBM SP UART not registered, owned by service processor\n"); + sp->serial_line = -1; + return; + } + + memset(&uart, 0, sizeof(uart)); + uart.port.irq = sp->irq; + uart.port.uartclk = 3686400; + uart.port.flags = UPF_SHARE_IRQ; + uart.port.iotype = UPIO_MEM; + uart.port.membase = iomem_base; + + sp->serial_line = serial8250_register_8250_port(&uart); + if (sp->serial_line < 0) { + dev_err(sp->dev, "Failed to register serial port\n"); + return; + } + enable_uart_interrupts(sp->base_address); +} + +void ibmasm_unregister_uart(struct service_processor *sp) +{ + if (sp->serial_line < 0) + return; + + disable_uart_interrupts(sp->base_address); + serial8250_unregister_port(sp->serial_line); +} -- cgit v1.3.1