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/hexagon/lib/divsi3.S | 67 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) create mode 100644 arch/hexagon/lib/divsi3.S (limited to 'arch/hexagon/lib/divsi3.S') diff --git a/arch/hexagon/lib/divsi3.S b/arch/hexagon/lib/divsi3.S new file mode 100644 index 000000000..783e09424 --- /dev/null +++ b/arch/hexagon/lib/divsi3.S @@ -0,0 +1,67 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (c) 2021, The Linux Foundation. All rights reserved. + */ + +#include + +SYM_FUNC_START(__hexagon_divsi3) + { + p0 = cmp.gt(r0,#-1) + p1 = cmp.gt(r1,#-1) + r3:2 = vabsw(r1:0) + } + { + p3 = xor(p0,p1) + r4 = sub(r2,r3) + r6 = cl0(r2) + p0 = cmp.gtu(r3,r2) + } + { + r0 = mux(p3,#-1,#1) + r7 = cl0(r3) + p1 = cmp.gtu(r3,r4) + } + { + r0 = mux(p0,#0,r0) + p0 = or(p0,p1) + if (p0.new) jumpr:nt r31 + r6 = sub(r7,r6) + } + { + r7 = r6 + r5:4 = combine(#1,r3) + r6 = add(#1,lsr(r6,#1)) + p0 = cmp.gtu(r6,#4) + } + { + r5:4 = vaslw(r5:4,r7) + if (!p0) r6 = #3 + } + { + loop0(1f,r6) + r7:6 = vlsrw(r5:4,#1) + r1:0 = #0 + } + .falign +1: + { + r5:4 = vlsrw(r5:4,#2) + if (!p0.new) r0 = add(r0,r5) + if (!p0.new) r2 = sub(r2,r4) + p0 = cmp.gtu(r4,r2) + } + { + r7:6 = vlsrw(r7:6,#2) + if (!p0.new) r0 = add(r0,r7) + if (!p0.new) r2 = sub(r2,r6) + p0 = cmp.gtu(r6,r2) + }:endloop0 + { + if (!p0) r0 = add(r0,r7) + } + { + if (p3) r0 = sub(r1,r0) + jumpr r31 + } +SYM_FUNC_END(__hexagon_divsi3) -- cgit v1.3.1