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/generic/board-ranchu.c | 90 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) create mode 100644 arch/mips/generic/board-ranchu.c (limited to 'arch/mips/generic/board-ranchu.c') diff --git a/arch/mips/generic/board-ranchu.c b/arch/mips/generic/board-ranchu.c new file mode 100644 index 000000000..930c45041 --- /dev/null +++ b/arch/mips/generic/board-ranchu.c @@ -0,0 +1,90 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Support code for virtual Ranchu board for MIPS. + * + * Author: Miodrag Dinic + */ + +#include +#include + +#include +#include +#include + +#define GOLDFISH_TIMER_LOW 0x00 +#define GOLDFISH_TIMER_HIGH 0x04 + +static __init u64 read_rtc_time(void __iomem *base) +{ + u32 time_low; + u32 time_high; + + /* + * Reading the low address latches the high value + * as well so there is no fear that we may read + * inaccurate high value. + */ + time_low = readl(base + GOLDFISH_TIMER_LOW); + time_high = readl(base + GOLDFISH_TIMER_HIGH); + + return ((u64)time_high << 32) | time_low; +} + +static __init unsigned int ranchu_measure_hpt_freq(void) +{ + u64 rtc_start, rtc_current, rtc_delta; + unsigned int start, count; + struct device_node *np; + void __iomem *rtc_base; + + np = of_find_compatible_node(NULL, NULL, "google,goldfish-rtc"); + if (!np) + panic("%s(): Failed to find 'google,goldfish-rtc' dt node!", + __func__); + + rtc_base = of_iomap(np, 0); + of_node_put(np); + if (!rtc_base) + panic("%s(): Failed to ioremap Goldfish RTC base!", __func__); + + /* + * Poll the nanosecond resolution RTC for one + * second to calibrate the CPU frequency. + */ + rtc_start = read_rtc_time(rtc_base); + start = read_c0_count(); + + do { + rtc_current = read_rtc_time(rtc_base); + rtc_delta = rtc_current - rtc_start; + } while (rtc_delta < NSEC_PER_SEC); + + count = read_c0_count() - start; + + /* + * Make sure the frequency will be a round number. + * Without this correction, the returned value may vary + * between subsequent emulation executions. + * + * TODO: Set this value using device tree. + */ + count += 5000; + count -= count % 10000; + + iounmap(rtc_base); + + return count; +} + +static const struct of_device_id ranchu_of_match[] __initconst = { + { + .compatible = "mti,ranchu", + }, + {} +}; + +MIPS_MACHINE(ranchu) = { + .matches = ranchu_of_match, + .measure_hpt_freq = ranchu_measure_hpt_freq, +}; -- cgit v1.3.1