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 --- arch/powerpc/boot/mpc52xx-psc.c | 65 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 arch/powerpc/boot/mpc52xx-psc.c (limited to 'arch/powerpc/boot/mpc52xx-psc.c') diff --git a/arch/powerpc/boot/mpc52xx-psc.c b/arch/powerpc/boot/mpc52xx-psc.c new file mode 100644 index 000000000..c2c08633e --- /dev/null +++ b/arch/powerpc/boot/mpc52xx-psc.c @@ -0,0 +1,65 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * MPC5200 PSC serial console support. + * + * Author: Grant Likely + * + * Copyright (c) 2007 Secret Lab Technologies Ltd. + * Copyright (c) 2007 Freescale Semiconductor, Inc. + * + * It is assumed that the firmware (or the platform file) has already set + * up the port. + */ + +#include "types.h" +#include "io.h" +#include "ops.h" + +/* Programmable Serial Controller (PSC) status register bits */ +#define MPC52xx_PSC_SR 0x04 +#define MPC52xx_PSC_SR_RXRDY 0x0100 +#define MPC52xx_PSC_SR_RXFULL 0x0200 +#define MPC52xx_PSC_SR_TXRDY 0x0400 +#define MPC52xx_PSC_SR_TXEMP 0x0800 + +#define MPC52xx_PSC_BUFFER 0x0C + +static void *psc; + +static int psc_open(void) +{ + /* Assume the firmware has already configured the PSC into + * uart mode */ + return 0; +} + +static void psc_putc(unsigned char c) +{ + while (!(in_be16(psc + MPC52xx_PSC_SR) & MPC52xx_PSC_SR_TXRDY)) ; + out_8(psc + MPC52xx_PSC_BUFFER, c); +} + +static unsigned char psc_tstc(void) +{ + return (in_be16(psc + MPC52xx_PSC_SR) & MPC52xx_PSC_SR_RXRDY) != 0; +} + +static unsigned char psc_getc(void) +{ + while (!(in_be16(psc + MPC52xx_PSC_SR) & MPC52xx_PSC_SR_RXRDY)) ; + return in_8(psc + MPC52xx_PSC_BUFFER); +} + +int mpc5200_psc_console_init(void *devp, struct serial_console_data *scdp) +{ + /* Get the base address of the psc registers */ + if (dt_get_virtual_reg(devp, &psc, 1) < 1) + return -1; + + scdp->open = psc_open; + scdp->putc = psc_putc; + scdp->getc = psc_getc; + scdp->tstc = psc_tstc; + + return 0; +} -- cgit v1.3.1