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/riscv/lib/ashldi3.S | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) create mode 100644 arch/riscv/lib/ashldi3.S (limited to 'arch/riscv/lib/ashldi3.S') diff --git a/arch/riscv/lib/ashldi3.S b/arch/riscv/lib/ashldi3.S new file mode 100644 index 000000000..c3408862e --- /dev/null +++ b/arch/riscv/lib/ashldi3.S @@ -0,0 +1,36 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/** + * Adopted for the Linux kernel from IPXE project, see + * https://github.com/ipxe/ipxe/blob/master/src/arch/riscv32/libgcc/llshift.S + */ + +#include +#include + +/** + * Shift left + * + * @v a1:a0 Value to shift + * @v a2 Shift amount + * @ret a1:a0 Shifted value + */ + +SYM_FUNC_START(__ashldi3) + + /* Perform shift by 32 bits, if applicable */ + li t0, 32 + sub t1, t0, a2 + bgtz t1, 1f + mv a1, a0 + mv a0, zero +1: /* Perform shift by modulo-32 bits, if applicable */ + andi a2, a2, 0x1f + beqz a2, 2f + srl t2, a0, t1 + sll a0, a0, a2 + sll a1, a1, a2 + or a1, a1, t2 +2: ret + +SYM_FUNC_END(__ashldi3) +EXPORT_SYMBOL(__ashldi3) -- cgit v1.3.1