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/mm/page-funcs.S | 53 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 arch/mips/mm/page-funcs.S (limited to 'arch/mips/mm/page-funcs.S') diff --git a/arch/mips/mm/page-funcs.S b/arch/mips/mm/page-funcs.S new file mode 100644 index 000000000..42d0516ca --- /dev/null +++ b/arch/mips/mm/page-funcs.S @@ -0,0 +1,53 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Micro-assembler generated clear_page/copy_page functions. + * + * Copyright (C) 2012 MIPS Technologies, Inc. + * Copyright (C) 2012 Ralf Baechle + */ +#include +#include +#include + +#ifdef CONFIG_SIBYTE_DMA_PAGEOPS +#define cpu_clear_page_function_name clear_page_cpu +#define cpu_copy_page_function_name copy_page_cpu +#else +#define cpu_clear_page_function_name clear_page +#define cpu_copy_page_function_name copy_page +#endif + +/* + * Maximum sizes: + * + * R4000 128 bytes S-cache: 0x058 bytes + * R4600 v1.7: 0x05c bytes + * R4600 v2.0: 0x060 bytes + * With prefetching, 16 word strides 0x120 bytes + */ +EXPORT(__clear_page_start) +LEAF(cpu_clear_page_function_name) +EXPORT_SYMBOL(cpu_clear_page_function_name) +1: j 1b /* Dummy, will be replaced. */ + .space 288 +END(cpu_clear_page_function_name) +EXPORT(__clear_page_end) + +/* + * Maximum sizes: + * + * R4000 128 bytes S-cache: 0x11c bytes + * R4600 v1.7: 0x080 bytes + * R4600 v2.0: 0x07c bytes + * With prefetching, 16 word strides 0x540 bytes + */ +EXPORT(__copy_page_start) +LEAF(cpu_copy_page_function_name) +EXPORT_SYMBOL(cpu_copy_page_function_name) +1: j 1b /* Dummy, will be replaced. */ + .space 1344 +END(cpu_copy_page_function_name) +EXPORT(__copy_page_end) -- cgit v1.3.1