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/mips/rb532/time.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 arch/mips/rb532/time.c (limited to 'arch/mips/rb532/time.c') diff --git a/arch/mips/rb532/time.c b/arch/mips/rb532/time.c new file mode 100644 index 000000000..68713dd32 --- /dev/null +++ b/arch/mips/rb532/time.c @@ -0,0 +1,54 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Carsten Langgaard, carstenl@mips.com + * Copyright (C) 1999,2000 MIPS Technologies, Inc. All rights reserved. + * + * Setting up the clock on the MIPS boards. + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +extern unsigned int idt_cpu_freq; + +/* + * Figure out the r4k offset, the amount to increment the compare + * register for each time tick. There is no RTC available. + * + * The RC32434 counts at half the CPU *core* speed. + */ +static unsigned long __init cal_r4koff(void) +{ + mips_hpt_frequency = idt_cpu_freq * IDT_CLOCK_MULT / 2; + + return mips_hpt_frequency / HZ; +} + +void __init plat_time_init(void) +{ + unsigned int est_freq; + unsigned long flags, r4k_offset; + + local_irq_save(flags); + + printk(KERN_INFO "calculating r4koff... "); + r4k_offset = cal_r4koff(); + printk("%08lx(%d)\n", r4k_offset, (int) r4k_offset); + + est_freq = 2 * r4k_offset * HZ; + est_freq += 5000; /* round */ + est_freq -= est_freq % 10000; + printk(KERN_INFO "CPU frequency %d.%02d MHz\n", est_freq / 1000000, + (est_freq % 1000000) * 100 / 1000000); + local_irq_restore(flags); +} -- cgit v1.3.1