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/arm64/mm/dma-mapping.c | 59 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) create mode 100644 arch/arm64/mm/dma-mapping.c (limited to 'arch/arm64/mm/dma-mapping.c') diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c new file mode 100644 index 000000000..7f6f2f40d --- /dev/null +++ b/arch/arm64/mm/dma-mapping.c @@ -0,0 +1,59 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2012 ARM Ltd. + * Author: Catalin Marinas + */ + +#include +#include +#include +#include + +#include +#include + +void arch_sync_dma_for_device(phys_addr_t paddr, size_t size, + enum dma_data_direction dir) +{ + unsigned long start = (unsigned long)phys_to_virt(paddr); + + dcache_clean_poc_nosync(start, start + size); +} + +void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size, + enum dma_data_direction dir) +{ + unsigned long start = (unsigned long)phys_to_virt(paddr); + + if (dir == DMA_TO_DEVICE) + return; + + dcache_inval_poc_nosync(start, start + size); +} + +void arch_dma_prep_coherent(struct page *page, size_t size) +{ + unsigned long start = (unsigned long)page_address(page); + + dcache_clean_poc(start, start + size); +} + +void arch_setup_dma_ops(struct device *dev, bool coherent) +{ + int cls = cache_line_size_of_cpu(); + + if (!coherent && !CLIDR_LOC(read_sysreg(clidr_el1))) { + dev_warn(dev, "CLIDR_EL1.LoC == 0, treating as coherent\n"); + coherent = true; + } + + WARN_TAINT(!coherent && cls > ARCH_DMA_MINALIGN, + TAINT_CPU_OUT_OF_SPEC, + "%s %s: ARCH_DMA_MINALIGN smaller than CTR_EL0.CWG (%d < %d)", + dev_driver_string(dev), dev_name(dev), + ARCH_DMA_MINALIGN, cls); + + dev_assign_dma_coherent(dev, coherent); + + xen_setup_dma_ops(dev); +} -- cgit v1.3.1